2007-10-16 23:29:46 -07:00
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2005-04-16 15:20:36 -07:00
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2008-04-29 01:01:31 -07:00
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2005-04-16 15:20:36 -07:00
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2006-06-27 02:53:54 -07:00
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2005-04-16 15:20:36 -07:00
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2005-10-30 15:02:44 -08:00
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2005-04-16 15:20:36 -07:00
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2006-06-26 00:24:54 -07:00
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2005-04-16 15:20:36 -07:00
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2011-08-22 14:09:11 +01:00
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2005-04-16 15:20:36 -07:00
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2014-09-02 13:52:05 +01:00
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2008-04-29 01:01:32 -07:00
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2005-04-16 15:20:36 -07:00
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2011-01-20 16:38:33 +00:00
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2007-10-16 23:29:46 -07:00
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2005-04-16 15:20:36 -07:00
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2011-01-20 16:38:33 +00:00
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2005-04-16 15:20:36 -07:00
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2012-02-08 07:53:04 -08:00
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2005-04-16 15:20:36 -07:00
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2011-01-20 16:38:33 +00:00
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2005-04-16 15:20:36 -07:00
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2012-02-08 07:53:04 -08:00
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2005-04-16 15:20:36 -07:00
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2012-02-08 07:53:04 -08:00
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2009-02-26 18:27:38 -06:00
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2005-04-16 15:20:36 -07:00
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2007-10-16 23:29:46 -07:00
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2005-04-16 15:20:36 -07:00
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2011-01-20 16:38:33 +00:00
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2005-04-16 15:20:36 -07:00
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2005-11-07 01:01:35 -08:00
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2011-01-20 16:38:33 +00:00
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2005-04-16 15:20:36 -07:00
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2011-01-20 16:38:27 +00:00
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2005-04-16 15:20:36 -07:00
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2011-01-20 16:38:33 +00:00
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2005-04-16 15:20:36 -07:00
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2011-01-20 16:38:27 +00:00
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2005-04-16 15:20:36 -07:00
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2011-01-20 16:38:33 +00:00
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2005-04-16 15:20:36 -07:00
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2006-06-26 00:24:54 -07:00
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2005-04-16 15:20:36 -07:00
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2006-06-26 00:24:54 -07:00
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2005-04-16 15:20:36 -07:00
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2007-02-06 13:45:51 +00:00
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2005-04-16 15:20:36 -07:00
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2007-02-06 13:45:51 +00:00
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2005-04-16 15:20:36 -07:00
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2006-06-26 00:24:54 -07:00
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2005-04-16 15:20:36 -07:00
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2006-06-26 00:24:54 -07:00
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2007-02-06 13:45:51 +00:00
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2005-04-16 15:20:36 -07:00
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2007-02-06 13:45:51 +00:00
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2005-04-16 15:20:36 -07:00
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2007-02-06 13:45:51 +00:00
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2005-04-16 15:20:36 -07:00
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2011-01-20 16:38:27 +00:00
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2005-04-16 15:20:36 -07:00
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2011-01-20 16:38:33 +00:00
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2005-04-16 15:20:36 -07:00
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2012-02-08 07:53:04 -08:00
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2006-06-26 00:24:50 -07:00
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2005-04-16 15:20:36 -07:00
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2005-10-30 15:02:44 -08:00
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2005-04-16 15:20:36 -07:00
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2011-03-07 15:05:59 +00:00
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2013-09-24 10:35:15 +01:00
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2005-04-16 15:20:36 -07:00
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2012-02-08 07:53:04 -08:00
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2005-04-16 15:20:36 -07:00
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2006-06-26 00:24:50 -07:00
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2012-02-08 07:53:04 -08:00
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2008-04-29 01:01:32 -07:00
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2012-02-08 07:53:04 -08:00
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2008-04-29 01:01:32 -07:00
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2005-04-16 15:20:36 -07:00
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2006-06-26 00:24:50 -07:00
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2008-04-29 01:01:32 -07:00
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2006-06-26 00:24:50 -07:00
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2005-04-16 15:20:36 -07:00
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2013-12-02 11:24:18 +00:00
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2005-04-16 15:20:36 -07:00
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2014-12-11 19:59:38 +00:00
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2015-10-21 14:04:47 +01:00
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2014-12-11 19:59:38 +00:00
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2005-04-16 15:20:36 -07:00
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2011-11-16 11:15:54 +00:00
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2013-09-24 10:35:15 +01:00
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2005-04-16 15:20:36 -07:00
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2006-06-26 00:24:50 -07:00
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2005-06-23 22:00:49 -07:00
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2013-08-30 16:07:37 +01:00
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2005-04-16 15:20:36 -07:00
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2005-10-30 15:02:44 -08:00
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CRED: Inaugurate COW credentials
Inaugurate copy-on-write credentials management. This uses RCU to manage the
credentials pointer in the task_struct with respect to accesses by other tasks.
A process may only modify its own credentials, and so does not need locking to
access or modify its own credentials.
A mutex (cred_replace_mutex) is added to the task_struct to control the effect
of PTRACE_ATTACHED on credential calculations, particularly with respect to
execve().
With this patch, the contents of an active credentials struct may not be
changed directly; rather a new set of credentials must be prepared, modified
and committed using something like the following sequence of events:
struct cred *new = prepare_creds();
int ret = blah(new);
if (ret < 0) {
abort_creds(new);
return ret;
}
return commit_creds(new);
There are some exceptions to this rule: the keyrings pointed to by the active
credentials may be instantiated - keyrings violate the COW rule as managing
COW keyrings is tricky, given that it is possible for a task to directly alter
the keys in a keyring in use by another task.
To help enforce this, various pointers to sets of credentials, such as those in
the task_struct, are declared const. The purpose of this is compile-time
discouragement of altering credentials through those pointers. Once a set of
credentials has been made public through one of these pointers, it may not be
modified, except under special circumstances:
(1) Its reference count may incremented and decremented.
(2) The keyrings to which it points may be modified, but not replaced.
The only safe way to modify anything else is to create a replacement and commit
using the functions described in Documentation/credentials.txt (which will be
added by a later patch).
This patch and the preceding patches have been tested with the LTP SELinux
testsuite.
This patch makes several logical sets of alteration:
(1) execve().
This now prepares and commits credentials in various places in the
security code rather than altering the current creds directly.
(2) Temporary credential overrides.
do_coredump() and sys_faccessat() now prepare their own credentials and
temporarily override the ones currently on the acting thread, whilst
preventing interference from other threads by holding cred_replace_mutex
on the thread being dumped.
This will be replaced in a future patch by something that hands down the
credentials directly to the functions being called, rather than altering
the task's objective credentials.
(3) LSM interface.
A number of functions have been changed, added or removed:
(*) security_capset_check(), ->capset_check()
(*) security_capset_set(), ->capset_set()
Removed in favour of security_capset().
(*) security_capset(), ->capset()
New. This is passed a pointer to the new creds, a pointer to the old
creds and the proposed capability sets. It should fill in the new
creds or return an error. All pointers, barring the pointer to the
new creds, are now const.
(*) security_bprm_apply_creds(), ->bprm_apply_creds()
Changed; now returns a value, which will cause the process to be
killed if it's an error.
(*) security_task_alloc(), ->task_alloc_security()
Removed in favour of security_prepare_creds().
(*) security_cred_free(), ->cred_free()
New. Free security data attached to cred->security.
(*) security_prepare_creds(), ->cred_prepare()
New. Duplicate any security data attached to cred->security.
(*) security_commit_creds(), ->cred_commit()
New. Apply any security effects for the upcoming installation of new
security by commit_creds().
(*) security_task_post_setuid(), ->task_post_setuid()
Removed in favour of security_task_fix_setuid().
(*) security_task_fix_setuid(), ->task_fix_setuid()
Fix up the proposed new credentials for setuid(). This is used by
cap_set_fix_setuid() to implicitly adjust capabilities in line with
setuid() changes. Changes are made to the new credentials, rather
than the task itself as in security_task_post_setuid().
(*) security_task_reparent_to_init(), ->task_reparent_to_init()
Removed. Instead the task being reparented to init is referred
directly to init's credentials.
NOTE! This results in the loss of some state: SELinux's osid no
longer records the sid of the thread that forked it.
(*) security_key_alloc(), ->key_alloc()
(*) security_key_permission(), ->key_permission()
Changed. These now take cred pointers rather than task pointers to
refer to the security context.
(4) sys_capset().
This has been simplified and uses less locking. The LSM functions it
calls have been merged.
(5) reparent_to_kthreadd().
This gives the current thread the same credentials as init by simply using
commit_thread() to point that way.
(6) __sigqueue_alloc() and switch_uid()
__sigqueue_alloc() can't stop the target task from changing its creds
beneath it, so this function gets a reference to the currently applicable
user_struct which it then passes into the sigqueue struct it returns if
successful.
switch_uid() is now called from commit_creds(), and possibly should be
folded into that. commit_creds() should take care of protecting
__sigqueue_alloc().
(7) [sg]et[ug]id() and co and [sg]et_current_groups.
The set functions now all use prepare_creds(), commit_creds() and
abort_creds() to build and check a new set of credentials before applying
it.
security_task_set[ug]id() is called inside the prepared section. This
guarantees that nothing else will affect the creds until we've finished.
The calling of set_dumpable() has been moved into commit_creds().
Much of the functionality of set_user() has been moved into
commit_creds().
The get functions all simply access the data directly.
(8) security_task_prctl() and cap_task_prctl().
security_task_prctl() has been modified to return -ENOSYS if it doesn't
want to handle a function, or otherwise return the return value directly
rather than through an argument.
Additionally, cap_task_prctl() now prepares a new set of credentials, even
if it doesn't end up using it.
(9) Keyrings.
A number of changes have been made to the keyrings code:
(a) switch_uid_keyring(), copy_keys(), exit_keys() and suid_keys() have
all been dropped and built in to the credentials functions directly.
They may want separating out again later.
(b) key_alloc() and search_process_keyrings() now take a cred pointer
rather than a task pointer to specify the security context.
(c) copy_creds() gives a new thread within the same thread group a new
thread keyring if its parent had one, otherwise it discards the thread
keyring.
(d) The authorisation key now points directly to the credentials to extend
the search into rather pointing to the task that carries them.
(e) Installing thread, process or session keyrings causes a new set of
credentials to be created, even though it's not strictly necessary for
process or session keyrings (they're shared).
(10) Usermode helper.
The usermode helper code now carries a cred struct pointer in its
subprocess_info struct instead of a new session keyring pointer. This set
of credentials is derived from init_cred and installed on the new process
after it has been cloned.
call_usermodehelper_setup() allocates the new credentials and
call_usermodehelper_freeinfo() discards them if they haven't been used. A
special cred function (prepare_usermodeinfo_creds()) is provided
specifically for call_usermodehelper_setup() to call.
call_usermodehelper_setkeys() adjusts the credentials to sport the
supplied keyring as the new session keyring.
(11) SELinux.
SELinux has a number of changes, in addition to those to support the LSM
interface changes mentioned above:
(a) selinux_setprocattr() no longer does its check for whether the
current ptracer can access processes with the new SID inside the lock
that covers getting the ptracer's SID. Whilst this lock ensures that
the check is done with the ptracer pinned, the result is only valid
until the lock is released, so there's no point doing it inside the
lock.
(12) is_single_threaded().
This function has been extracted from selinux_setprocattr() and put into
a file of its own in the lib/ directory as join_session_keyring() now
wants to use it too.
The code in SELinux just checked to see whether a task shared mm_structs
with other tasks (CLONE_VM), but that isn't good enough. We really want
to know if they're part of the same thread group (CLONE_THREAD).
(13) nfsd.
The NFS server daemon now has to use the COW credentials to set the
credentials it is going to use. It really needs to pass the credentials
down to the functions it calls, but it can't do that until other patches
in this series have been applied.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: James Morris <jmorris@namei.org>
Signed-off-by: James Morris <jmorris@namei.org>
2008-11-14 10:39:23 +11:00
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2005-10-30 15:02:44 -08:00
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2005-04-16 15:20:36 -07:00
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2005-10-30 15:02:44 -08:00
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2005-04-16 15:20:36 -07:00
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2005-10-30 15:02:44 -08:00
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2005-04-16 15:20:36 -07:00
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2006-06-26 00:24:50 -07:00
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2005-04-16 15:20:36 -07:00
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2005-10-30 15:02:44 -08:00
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2006-06-26 00:24:50 -07:00
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2005-10-30 15:02:44 -08:00
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2005-04-16 15:20:36 -07:00
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2005-10-30 15:02:44 -08:00
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2005-04-16 15:20:36 -07:00
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2011-01-20 16:38:27 +00:00
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2005-04-16 15:20:36 -07:00
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2011-01-20 16:38:33 +00:00
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2005-04-16 15:20:36 -07:00
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2010-04-21 00:02:11 -07:00
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2005-04-16 15:20:36 -07:00
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2005-06-23 22:00:49 -07:00
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2012-02-08 07:53:04 -08:00
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2008-04-29 01:01:32 -07:00
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2005-04-16 15:20:36 -07:00
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2008-04-29 01:01:32 -07:00
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2005-04-16 15:20:36 -07:00
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2011-01-20 16:38:27 +00:00
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2005-04-16 15:20:36 -07:00
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2011-01-20 16:38:33 +00:00
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2005-04-16 15:20:36 -07:00
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2012-09-13 13:06:29 +01:00
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[PATCH] Keys: Make request-key create an authorisation key
The attached patch makes the following changes:
(1) There's a new special key type called ".request_key_auth".
This is an authorisation key for when one process requests a key and
another process is started to construct it. This type of key cannot be
created by the user; nor can it be requested by kernel services.
Authorisation keys hold two references:
(a) Each refers to a key being constructed. When the key being
constructed is instantiated the authorisation key is revoked,
rendering it of no further use.
(b) The "authorising process". This is either:
(i) the process that called request_key(), or:
(ii) if the process that called request_key() itself had an
authorisation key in its session keyring, then the authorising
process referred to by that authorisation key will also be
referred to by the new authorisation key.
This means that the process that initiated a chain of key requests
will authorise the lot of them, and will, by default, wind up with
the keys obtained from them in its keyrings.
(2) request_key() creates an authorisation key which is then passed to
/sbin/request-key in as part of a new session keyring.
(3) When request_key() is searching for a key to hand back to the caller, if
it comes across an authorisation key in the session keyring of the
calling process, it will also search the keyrings of the process
specified therein and it will use the specified process's credentials
(fsuid, fsgid, groups) to do that rather than the calling process's
credentials.
This allows a process started by /sbin/request-key to find keys belonging
to the authorising process.
(4) A key can be read, even if the process executing KEYCTL_READ doesn't have
direct read or search permission if that key is contained within the
keyrings of a process specified by an authorisation key found within the
calling process's session keyring, and is searchable using the
credentials of the authorising process.
This allows a process started by /sbin/request-key to read keys belonging
to the authorising process.
(5) The magic KEY_SPEC_*_KEYRING key IDs when passed to KEYCTL_INSTANTIATE or
KEYCTL_NEGATE will specify a keyring of the authorising process, rather
than the process doing the instantiation.
(6) One of the process keyrings can be nominated as the default to which
request_key() should attach new keys if not otherwise specified. This is
done with KEYCTL_SET_REQKEY_KEYRING and one of the KEY_REQKEY_DEFL_*
constants. The current setting can also be read using this call.
(7) request_key() is partially interruptible. If it is waiting for another
process to finish constructing a key, it can be interrupted. This permits
a request-key cycle to be broken without recourse to rebooting.
Signed-Off-By: David Howells <dhowells@redhat.com>
Signed-Off-By: Benoit Boissinot <benoit.boissinot@ens-lyon.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 22:00:56 -07:00
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2010-04-30 14:32:39 +01:00
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2013-09-24 10:35:18 +01:00
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2005-04-16 15:20:36 -07:00
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2007-10-16 23:29:46 -07:00
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2005-04-16 15:20:36 -07:00
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2005-06-23 22:00:49 -07:00
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2005-04-16 15:20:36 -07:00
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2012-09-13 13:06:29 +01:00
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2005-04-16 15:20:36 -07:00
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2005-06-23 22:00:49 -07:00
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2005-04-16 15:20:36 -07:00
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2005-06-23 22:00:49 -07:00
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2005-04-16 15:20:36 -07:00
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2013-09-24 10:35:18 +01:00
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[PATCH] Keys: Make request-key create an authorisation key
The attached patch makes the following changes:
(1) There's a new special key type called ".request_key_auth".
This is an authorisation key for when one process requests a key and
another process is started to construct it. This type of key cannot be
created by the user; nor can it be requested by kernel services.
Authorisation keys hold two references:
(a) Each refers to a key being constructed. When the key being
constructed is instantiated the authorisation key is revoked,
rendering it of no further use.
(b) The "authorising process". This is either:
(i) the process that called request_key(), or:
(ii) if the process that called request_key() itself had an
authorisation key in its session keyring, then the authorising
process referred to by that authorisation key will also be
referred to by the new authorisation key.
This means that the process that initiated a chain of key requests
will authorise the lot of them, and will, by default, wind up with
the keys obtained from them in its keyrings.
(2) request_key() creates an authorisation key which is then passed to
/sbin/request-key in as part of a new session keyring.
(3) When request_key() is searching for a key to hand back to the caller, if
it comes across an authorisation key in the session keyring of the
calling process, it will also search the keyrings of the process
specified therein and it will use the specified process's credentials
(fsuid, fsgid, groups) to do that rather than the calling process's
credentials.
This allows a process started by /sbin/request-key to find keys belonging
to the authorising process.
(4) A key can be read, even if the process executing KEYCTL_READ doesn't have
direct read or search permission if that key is contained within the
keyrings of a process specified by an authorisation key found within the
calling process's session keyring, and is searchable using the
credentials of the authorising process.
This allows a process started by /sbin/request-key to read keys belonging
to the authorising process.
(5) The magic KEY_SPEC_*_KEYRING key IDs when passed to KEYCTL_INSTANTIATE or
KEYCTL_NEGATE will specify a keyring of the authorising process, rather
than the process doing the instantiation.
(6) One of the process keyrings can be nominated as the default to which
request_key() should attach new keys if not otherwise specified. This is
done with KEYCTL_SET_REQKEY_KEYRING and one of the KEY_REQKEY_DEFL_*
constants. The current setting can also be read using this call.
(7) request_key() is partially interruptible. If it is waiting for another
process to finish constructing a key, it can be interrupted. This permits
a request-key cycle to be broken without recourse to rebooting.
Signed-Off-By: David Howells <dhowells@redhat.com>
Signed-Off-By: Benoit Boissinot <benoit.boissinot@ens-lyon.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 22:00:56 -07:00
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CRED: Inaugurate COW credentials
Inaugurate copy-on-write credentials management. This uses RCU to manage the
credentials pointer in the task_struct with respect to accesses by other tasks.
A process may only modify its own credentials, and so does not need locking to
access or modify its own credentials.
A mutex (cred_replace_mutex) is added to the task_struct to control the effect
of PTRACE_ATTACHED on credential calculations, particularly with respect to
execve().
With this patch, the contents of an active credentials struct may not be
changed directly; rather a new set of credentials must be prepared, modified
and committed using something like the following sequence of events:
struct cred *new = prepare_creds();
int ret = blah(new);
if (ret < 0) {
abort_creds(new);
return ret;
}
return commit_creds(new);
There are some exceptions to this rule: the keyrings pointed to by the active
credentials may be instantiated - keyrings violate the COW rule as managing
COW keyrings is tricky, given that it is possible for a task to directly alter
the keys in a keyring in use by another task.
To help enforce this, various pointers to sets of credentials, such as those in
the task_struct, are declared const. The purpose of this is compile-time
discouragement of altering credentials through those pointers. Once a set of
credentials has been made public through one of these pointers, it may not be
modified, except under special circumstances:
(1) Its reference count may incremented and decremented.
(2) The keyrings to which it points may be modified, but not replaced.
The only safe way to modify anything else is to create a replacement and commit
using the functions described in Documentation/credentials.txt (which will be
added by a later patch).
This patch and the preceding patches have been tested with the LTP SELinux
testsuite.
This patch makes several logical sets of alteration:
(1) execve().
This now prepares and commits credentials in various places in the
security code rather than altering the current creds directly.
(2) Temporary credential overrides.
do_coredump() and sys_faccessat() now prepare their own credentials and
temporarily override the ones currently on the acting thread, whilst
preventing interference from other threads by holding cred_replace_mutex
on the thread being dumped.
This will be replaced in a future patch by something that hands down the
credentials directly to the functions being called, rather than altering
the task's objective credentials.
(3) LSM interface.
A number of functions have been changed, added or removed:
(*) security_capset_check(), ->capset_check()
(*) security_capset_set(), ->capset_set()
Removed in favour of security_capset().
(*) security_capset(), ->capset()
New. This is passed a pointer to the new creds, a pointer to the old
creds and the proposed capability sets. It should fill in the new
creds or return an error. All pointers, barring the pointer to the
new creds, are now const.
(*) security_bprm_apply_creds(), ->bprm_apply_creds()
Changed; now returns a value, which will cause the process to be
killed if it's an error.
(*) security_task_alloc(), ->task_alloc_security()
Removed in favour of security_prepare_creds().
(*) security_cred_free(), ->cred_free()
New. Free security data attached to cred->security.
(*) security_prepare_creds(), ->cred_prepare()
New. Duplicate any security data attached to cred->security.
(*) security_commit_creds(), ->cred_commit()
New. Apply any security effects for the upcoming installation of new
security by commit_creds().
(*) security_task_post_setuid(), ->task_post_setuid()
Removed in favour of security_task_fix_setuid().
(*) security_task_fix_setuid(), ->task_fix_setuid()
Fix up the proposed new credentials for setuid(). This is used by
cap_set_fix_setuid() to implicitly adjust capabilities in line with
setuid() changes. Changes are made to the new credentials, rather
than the task itself as in security_task_post_setuid().
(*) security_task_reparent_to_init(), ->task_reparent_to_init()
Removed. Instead the task being reparented to init is referred
directly to init's credentials.
NOTE! This results in the loss of some state: SELinux's osid no
longer records the sid of the thread that forked it.
(*) security_key_alloc(), ->key_alloc()
(*) security_key_permission(), ->key_permission()
Changed. These now take cred pointers rather than task pointers to
refer to the security context.
(4) sys_capset().
This has been simplified and uses less locking. The LSM functions it
calls have been merged.
(5) reparent_to_kthreadd().
This gives the current thread the same credentials as init by simply using
commit_thread() to point that way.
(6) __sigqueue_alloc() and switch_uid()
__sigqueue_alloc() can't stop the target task from changing its creds
beneath it, so this function gets a reference to the currently applicable
user_struct which it then passes into the sigqueue struct it returns if
successful.
switch_uid() is now called from commit_creds(), and possibly should be
folded into that. commit_creds() should take care of protecting
__sigqueue_alloc().
(7) [sg]et[ug]id() and co and [sg]et_current_groups.
The set functions now all use prepare_creds(), commit_creds() and
abort_creds() to build and check a new set of credentials before applying
it.
security_task_set[ug]id() is called inside the prepared section. This
guarantees that nothing else will affect the creds until we've finished.
The calling of set_dumpable() has been moved into commit_creds().
Much of the functionality of set_user() has been moved into
commit_creds().
The get functions all simply access the data directly.
(8) security_task_prctl() and cap_task_prctl().
security_task_prctl() has been modified to return -ENOSYS if it doesn't
want to handle a function, or otherwise return the return value directly
rather than through an argument.
Additionally, cap_task_prctl() now prepares a new set of credentials, even
if it doesn't end up using it.
(9) Keyrings.
A number of changes have been made to the keyrings code:
(a) switch_uid_keyring(), copy_keys(), exit_keys() and suid_keys() have
all been dropped and built in to the credentials functions directly.
They may want separating out again later.
(b) key_alloc() and search_process_keyrings() now take a cred pointer
rather than a task pointer to specify the security context.
(c) copy_creds() gives a new thread within the same thread group a new
thread keyring if its parent had one, otherwise it discards the thread
keyring.
(d) The authorisation key now points directly to the credentials to extend
the search into rather pointing to the task that carries them.
(e) Installing thread, process or session keyrings causes a new set of
credentials to be created, even though it's not strictly necessary for
process or session keyrings (they're shared).
(10) Usermode helper.
The usermode helper code now carries a cred struct pointer in its
subprocess_info struct instead of a new session keyring pointer. This set
of credentials is derived from init_cred and installed on the new process
after it has been cloned.
call_usermodehelper_setup() allocates the new credentials and
call_usermodehelper_freeinfo() discards them if they haven't been used. A
special cred function (prepare_usermodeinfo_creds()) is provided
specifically for call_usermodehelper_setup() to call.
call_usermodehelper_setkeys() adjusts the credentials to sport the
supplied keyring as the new session keyring.
(11) SELinux.
SELinux has a number of changes, in addition to those to support the LSM
interface changes mentioned above:
(a) selinux_setprocattr() no longer does its check for whether the
current ptracer can access processes with the new SID inside the lock
that covers getting the ptracer's SID. Whilst this lock ensures that
the check is done with the ptracer pinned, the result is only valid
until the lock is released, so there's no point doing it inside the
lock.
(12) is_single_threaded().
This function has been extracted from selinux_setprocattr() and put into
a file of its own in the lib/ directory as join_session_keyring() now
wants to use it too.
The code in SELinux just checked to see whether a task shared mm_structs
with other tasks (CLONE_VM), but that isn't good enough. We really want
to know if they're part of the same thread group (CLONE_THREAD).
(13) nfsd.
The NFS server daemon now has to use the COW credentials to set the
credentials it is going to use. It really needs to pass the credentials
down to the functions it calls, but it can't do that until other patches
in this series have been applied.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: James Morris <jmorris@namei.org>
Signed-off-by: James Morris <jmorris@namei.org>
2008-11-14 10:39:23 +11:00
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2014-07-18 18:56:34 +01:00
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2005-04-16 15:20:36 -07:00
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2007-10-16 23:29:46 -07:00
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2005-04-16 15:20:36 -07:00
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2007-10-16 23:29:46 -07:00
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2005-04-16 15:20:36 -07:00
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2011-01-20 16:38:27 +00:00
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2005-04-16 15:20:36 -07:00
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2011-01-20 16:38:33 +00:00
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2005-04-16 15:20:36 -07:00
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[PATCH] Keys: Make request-key create an authorisation key
The attached patch makes the following changes:
(1) There's a new special key type called ".request_key_auth".
This is an authorisation key for when one process requests a key and
another process is started to construct it. This type of key cannot be
created by the user; nor can it be requested by kernel services.
Authorisation keys hold two references:
(a) Each refers to a key being constructed. When the key being
constructed is instantiated the authorisation key is revoked,
rendering it of no further use.
(b) The "authorising process". This is either:
(i) the process that called request_key(), or:
(ii) if the process that called request_key() itself had an
authorisation key in its session keyring, then the authorising
process referred to by that authorisation key will also be
referred to by the new authorisation key.
This means that the process that initiated a chain of key requests
will authorise the lot of them, and will, by default, wind up with
the keys obtained from them in its keyrings.
(2) request_key() creates an authorisation key which is then passed to
/sbin/request-key in as part of a new session keyring.
(3) When request_key() is searching for a key to hand back to the caller, if
it comes across an authorisation key in the session keyring of the
calling process, it will also search the keyrings of the process
specified therein and it will use the specified process's credentials
(fsuid, fsgid, groups) to do that rather than the calling process's
credentials.
This allows a process started by /sbin/request-key to find keys belonging
to the authorising process.
(4) A key can be read, even if the process executing KEYCTL_READ doesn't have
direct read or search permission if that key is contained within the
keyrings of a process specified by an authorisation key found within the
calling process's session keyring, and is searchable using the
credentials of the authorising process.
This allows a process started by /sbin/request-key to read keys belonging
to the authorising process.
(5) The magic KEY_SPEC_*_KEYRING key IDs when passed to KEYCTL_INSTANTIATE or
KEYCTL_NEGATE will specify a keyring of the authorising process, rather
than the process doing the instantiation.
(6) One of the process keyrings can be nominated as the default to which
request_key() should attach new keys if not otherwise specified. This is
done with KEYCTL_SET_REQKEY_KEYRING and one of the KEY_REQKEY_DEFL_*
constants. The current setting can also be read using this call.
(7) request_key() is partially interruptible. If it is waiting for another
process to finish constructing a key, it can be interrupted. This permits
a request-key cycle to be broken without recourse to rebooting.
Signed-Off-By: David Howells <dhowells@redhat.com>
Signed-Off-By: Benoit Boissinot <benoit.boissinot@ens-lyon.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 22:00:56 -07:00
|
|
|
|
CRED: Inaugurate COW credentials
Inaugurate copy-on-write credentials management. This uses RCU to manage the
credentials pointer in the task_struct with respect to accesses by other tasks.
A process may only modify its own credentials, and so does not need locking to
access or modify its own credentials.
A mutex (cred_replace_mutex) is added to the task_struct to control the effect
of PTRACE_ATTACHED on credential calculations, particularly with respect to
execve().
With this patch, the contents of an active credentials struct may not be
changed directly; rather a new set of credentials must be prepared, modified
and committed using something like the following sequence of events:
struct cred *new = prepare_creds();
int ret = blah(new);
if (ret < 0) {
abort_creds(new);
return ret;
}
return commit_creds(new);
There are some exceptions to this rule: the keyrings pointed to by the active
credentials may be instantiated - keyrings violate the COW rule as managing
COW keyrings is tricky, given that it is possible for a task to directly alter
the keys in a keyring in use by another task.
To help enforce this, various pointers to sets of credentials, such as those in
the task_struct, are declared const. The purpose of this is compile-time
discouragement of altering credentials through those pointers. Once a set of
credentials has been made public through one of these pointers, it may not be
modified, except under special circumstances:
(1) Its reference count may incremented and decremented.
(2) The keyrings to which it points may be modified, but not replaced.
The only safe way to modify anything else is to create a replacement and commit
using the functions described in Documentation/credentials.txt (which will be
added by a later patch).
This patch and the preceding patches have been tested with the LTP SELinux
testsuite.
This patch makes several logical sets of alteration:
(1) execve().
This now prepares and commits credentials in various places in the
security code rather than altering the current creds directly.
(2) Temporary credential overrides.
do_coredump() and sys_faccessat() now prepare their own credentials and
temporarily override the ones currently on the acting thread, whilst
preventing interference from other threads by holding cred_replace_mutex
on the thread being dumped.
This will be replaced in a future patch by something that hands down the
credentials directly to the functions being called, rather than altering
the task's objective credentials.
(3) LSM interface.
A number of functions have been changed, added or removed:
(*) security_capset_check(), ->capset_check()
(*) security_capset_set(), ->capset_set()
Removed in favour of security_capset().
(*) security_capset(), ->capset()
New. This is passed a pointer to the new creds, a pointer to the old
creds and the proposed capability sets. It should fill in the new
creds or return an error. All pointers, barring the pointer to the
new creds, are now const.
(*) security_bprm_apply_creds(), ->bprm_apply_creds()
Changed; now returns a value, which will cause the process to be
killed if it's an error.
(*) security_task_alloc(), ->task_alloc_security()
Removed in favour of security_prepare_creds().
(*) security_cred_free(), ->cred_free()
New. Free security data attached to cred->security.
(*) security_prepare_creds(), ->cred_prepare()
New. Duplicate any security data attached to cred->security.
(*) security_commit_creds(), ->cred_commit()
New. Apply any security effects for the upcoming installation of new
security by commit_creds().
(*) security_task_post_setuid(), ->task_post_setuid()
Removed in favour of security_task_fix_setuid().
(*) security_task_fix_setuid(), ->task_fix_setuid()
Fix up the proposed new credentials for setuid(). This is used by
cap_set_fix_setuid() to implicitly adjust capabilities in line with
setuid() changes. Changes are made to the new credentials, rather
than the task itself as in security_task_post_setuid().
(*) security_task_reparent_to_init(), ->task_reparent_to_init()
Removed. Instead the task being reparented to init is referred
directly to init's credentials.
NOTE! This results in the loss of some state: SELinux's osid no
longer records the sid of the thread that forked it.
(*) security_key_alloc(), ->key_alloc()
(*) security_key_permission(), ->key_permission()
Changed. These now take cred pointers rather than task pointers to
refer to the security context.
(4) sys_capset().
This has been simplified and uses less locking. The LSM functions it
calls have been merged.
(5) reparent_to_kthreadd().
This gives the current thread the same credentials as init by simply using
commit_thread() to point that way.
(6) __sigqueue_alloc() and switch_uid()
__sigqueue_alloc() can't stop the target task from changing its creds
beneath it, so this function gets a reference to the currently applicable
user_struct which it then passes into the sigqueue struct it returns if
successful.
switch_uid() is now called from commit_creds(), and possibly should be
folded into that. commit_creds() should take care of protecting
__sigqueue_alloc().
(7) [sg]et[ug]id() and co and [sg]et_current_groups.
The set functions now all use prepare_creds(), commit_creds() and
abort_creds() to build and check a new set of credentials before applying
it.
security_task_set[ug]id() is called inside the prepared section. This
guarantees that nothing else will affect the creds until we've finished.
The calling of set_dumpable() has been moved into commit_creds().
Much of the functionality of set_user() has been moved into
commit_creds().
The get functions all simply access the data directly.
(8) security_task_prctl() and cap_task_prctl().
security_task_prctl() has been modified to return -ENOSYS if it doesn't
want to handle a function, or otherwise return the return value directly
rather than through an argument.
Additionally, cap_task_prctl() now prepares a new set of credentials, even
if it doesn't end up using it.
(9) Keyrings.
A number of changes have been made to the keyrings code:
(a) switch_uid_keyring(), copy_keys(), exit_keys() and suid_keys() have
all been dropped and built in to the credentials functions directly.
They may want separating out again later.
(b) key_alloc() and search_process_keyrings() now take a cred pointer
rather than a task pointer to specify the security context.
(c) copy_creds() gives a new thread within the same thread group a new
thread keyring if its parent had one, otherwise it discards the thread
keyring.
(d) The authorisation key now points directly to the credentials to extend
the search into rather pointing to the task that carries them.
(e) Installing thread, process or session keyrings causes a new set of
credentials to be created, even though it's not strictly necessary for
process or session keyrings (they're shared).
(10) Usermode helper.
The usermode helper code now carries a cred struct pointer in its
subprocess_info struct instead of a new session keyring pointer. This set
of credentials is derived from init_cred and installed on the new process
after it has been cloned.
call_usermodehelper_setup() allocates the new credentials and
call_usermodehelper_freeinfo() discards them if they haven't been used. A
special cred function (prepare_usermodeinfo_creds()) is provided
specifically for call_usermodehelper_setup() to call.
call_usermodehelper_setkeys() adjusts the credentials to sport the
supplied keyring as the new session keyring.
(11) SELinux.
SELinux has a number of changes, in addition to those to support the LSM
interface changes mentioned above:
(a) selinux_setprocattr() no longer does its check for whether the
current ptracer can access processes with the new SID inside the lock
that covers getting the ptracer's SID. Whilst this lock ensures that
the check is done with the ptracer pinned, the result is only valid
until the lock is released, so there's no point doing it inside the
lock.
(12) is_single_threaded().
This function has been extracted from selinux_setprocattr() and put into
a file of its own in the lib/ directory as join_session_keyring() now
wants to use it too.
The code in SELinux just checked to see whether a task shared mm_structs
with other tasks (CLONE_VM), but that isn't good enough. We really want
to know if they're part of the same thread group (CLONE_THREAD).
(13) nfsd.
The NFS server daemon now has to use the COW credentials to set the
credentials it is going to use. It really needs to pass the credentials
down to the functions it calls, but it can't do that until other patches
in this series have been applied.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: James Morris <jmorris@namei.org>
Signed-off-by: James Morris <jmorris@namei.org>
2008-11-14 10:39:23 +11:00
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2012-09-13 13:06:29 +01:00
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2014-07-18 18:56:34 +01:00
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2012-09-13 13:06:29 +01:00
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2010-04-30 14:32:39 +01:00
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2013-09-24 10:35:18 +01:00
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2010-04-30 14:32:39 +01:00
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2014-07-18 18:56:34 +01:00
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2010-04-30 14:32:39 +01:00
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2005-04-16 15:20:36 -07:00
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2013-09-24 10:35:18 +01:00
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2005-04-16 15:20:36 -07:00
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2014-07-18 18:56:34 +01:00
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2012-09-13 13:06:29 +01:00
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2005-04-16 15:20:36 -07:00
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2011-01-20 16:38:27 +00:00
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2005-04-16 15:20:36 -07:00
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2011-01-20 16:38:33 +00:00
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2011-03-07 15:06:09 +00:00
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2011-01-20 16:38:33 +00:00
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2011-03-07 15:06:09 +00:00
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2011-01-20 16:38:33 +00:00
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2011-03-07 15:06:09 +00:00
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2011-01-20 16:38:33 +00:00
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2011-03-07 15:06:09 +00:00
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2011-01-20 16:38:33 +00:00
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2005-04-16 15:20:36 -07:00
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2011-03-07 15:06:09 +00:00
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[PATCH] Keys: Make request-key create an authorisation key
The attached patch makes the following changes:
(1) There's a new special key type called ".request_key_auth".
This is an authorisation key for when one process requests a key and
another process is started to construct it. This type of key cannot be
created by the user; nor can it be requested by kernel services.
Authorisation keys hold two references:
(a) Each refers to a key being constructed. When the key being
constructed is instantiated the authorisation key is revoked,
rendering it of no further use.
(b) The "authorising process". This is either:
(i) the process that called request_key(), or:
(ii) if the process that called request_key() itself had an
authorisation key in its session keyring, then the authorising
process referred to by that authorisation key will also be
referred to by the new authorisation key.
This means that the process that initiated a chain of key requests
will authorise the lot of them, and will, by default, wind up with
the keys obtained from them in its keyrings.
(2) request_key() creates an authorisation key which is then passed to
/sbin/request-key in as part of a new session keyring.
(3) When request_key() is searching for a key to hand back to the caller, if
it comes across an authorisation key in the session keyring of the
calling process, it will also search the keyrings of the process
specified therein and it will use the specified process's credentials
(fsuid, fsgid, groups) to do that rather than the calling process's
credentials.
This allows a process started by /sbin/request-key to find keys belonging
to the authorising process.
(4) A key can be read, even if the process executing KEYCTL_READ doesn't have
direct read or search permission if that key is contained within the
keyrings of a process specified by an authorisation key found within the
calling process's session keyring, and is searchable using the
credentials of the authorising process.
This allows a process started by /sbin/request-key to read keys belonging
to the authorising process.
(5) The magic KEY_SPEC_*_KEYRING key IDs when passed to KEYCTL_INSTANTIATE or
KEYCTL_NEGATE will specify a keyring of the authorising process, rather
than the process doing the instantiation.
(6) One of the process keyrings can be nominated as the default to which
request_key() should attach new keys if not otherwise specified. This is
done with KEYCTL_SET_REQKEY_KEYRING and one of the KEY_REQKEY_DEFL_*
constants. The current setting can also be read using this call.
(7) request_key() is partially interruptible. If it is waiting for another
process to finish constructing a key, it can be interrupted. This permits
a request-key cycle to be broken without recourse to rebooting.
Signed-Off-By: David Howells <dhowells@redhat.com>
Signed-Off-By: Benoit Boissinot <benoit.boissinot@ens-lyon.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 22:00:56 -07:00
|
|
|
|
CRED: Inaugurate COW credentials
Inaugurate copy-on-write credentials management. This uses RCU to manage the
credentials pointer in the task_struct with respect to accesses by other tasks.
A process may only modify its own credentials, and so does not need locking to
access or modify its own credentials.
A mutex (cred_replace_mutex) is added to the task_struct to control the effect
of PTRACE_ATTACHED on credential calculations, particularly with respect to
execve().
With this patch, the contents of an active credentials struct may not be
changed directly; rather a new set of credentials must be prepared, modified
and committed using something like the following sequence of events:
struct cred *new = prepare_creds();
int ret = blah(new);
if (ret < 0) {
abort_creds(new);
return ret;
}
return commit_creds(new);
There are some exceptions to this rule: the keyrings pointed to by the active
credentials may be instantiated - keyrings violate the COW rule as managing
COW keyrings is tricky, given that it is possible for a task to directly alter
the keys in a keyring in use by another task.
To help enforce this, various pointers to sets of credentials, such as those in
the task_struct, are declared const. The purpose of this is compile-time
discouragement of altering credentials through those pointers. Once a set of
credentials has been made public through one of these pointers, it may not be
modified, except under special circumstances:
(1) Its reference count may incremented and decremented.
(2) The keyrings to which it points may be modified, but not replaced.
The only safe way to modify anything else is to create a replacement and commit
using the functions described in Documentation/credentials.txt (which will be
added by a later patch).
This patch and the preceding patches have been tested with the LTP SELinux
testsuite.
This patch makes several logical sets of alteration:
(1) execve().
This now prepares and commits credentials in various places in the
security code rather than altering the current creds directly.
(2) Temporary credential overrides.
do_coredump() and sys_faccessat() now prepare their own credentials and
temporarily override the ones currently on the acting thread, whilst
preventing interference from other threads by holding cred_replace_mutex
on the thread being dumped.
This will be replaced in a future patch by something that hands down the
credentials directly to the functions being called, rather than altering
the task's objective credentials.
(3) LSM interface.
A number of functions have been changed, added or removed:
(*) security_capset_check(), ->capset_check()
(*) security_capset_set(), ->capset_set()
Removed in favour of security_capset().
(*) security_capset(), ->capset()
New. This is passed a pointer to the new creds, a pointer to the old
creds and the proposed capability sets. It should fill in the new
creds or return an error. All pointers, barring the pointer to the
new creds, are now const.
(*) security_bprm_apply_creds(), ->bprm_apply_creds()
Changed; now returns a value, which will cause the process to be
killed if it's an error.
(*) security_task_alloc(), ->task_alloc_security()
Removed in favour of security_prepare_creds().
(*) security_cred_free(), ->cred_free()
New. Free security data attached to cred->security.
(*) security_prepare_creds(), ->cred_prepare()
New. Duplicate any security data attached to cred->security.
(*) security_commit_creds(), ->cred_commit()
New. Apply any security effects for the upcoming installation of new
security by commit_creds().
(*) security_task_post_setuid(), ->task_post_setuid()
Removed in favour of security_task_fix_setuid().
(*) security_task_fix_setuid(), ->task_fix_setuid()
Fix up the proposed new credentials for setuid(). This is used by
cap_set_fix_setuid() to implicitly adjust capabilities in line with
setuid() changes. Changes are made to the new credentials, rather
than the task itself as in security_task_post_setuid().
(*) security_task_reparent_to_init(), ->task_reparent_to_init()
Removed. Instead the task being reparented to init is referred
directly to init's credentials.
NOTE! This results in the loss of some state: SELinux's osid no
longer records the sid of the thread that forked it.
(*) security_key_alloc(), ->key_alloc()
(*) security_key_permission(), ->key_permission()
Changed. These now take cred pointers rather than task pointers to
refer to the security context.
(4) sys_capset().
This has been simplified and uses less locking. The LSM functions it
calls have been merged.
(5) reparent_to_kthreadd().
This gives the current thread the same credentials as init by simply using
commit_thread() to point that way.
(6) __sigqueue_alloc() and switch_uid()
__sigqueue_alloc() can't stop the target task from changing its creds
beneath it, so this function gets a reference to the currently applicable
user_struct which it then passes into the sigqueue struct it returns if
successful.
switch_uid() is now called from commit_creds(), and possibly should be
folded into that. commit_creds() should take care of protecting
__sigqueue_alloc().
(7) [sg]et[ug]id() and co and [sg]et_current_groups.
The set functions now all use prepare_creds(), commit_creds() and
abort_creds() to build and check a new set of credentials before applying
it.
security_task_set[ug]id() is called inside the prepared section. This
guarantees that nothing else will affect the creds until we've finished.
The calling of set_dumpable() has been moved into commit_creds().
Much of the functionality of set_user() has been moved into
commit_creds().
The get functions all simply access the data directly.
(8) security_task_prctl() and cap_task_prctl().
security_task_prctl() has been modified to return -ENOSYS if it doesn't
want to handle a function, or otherwise return the return value directly
rather than through an argument.
Additionally, cap_task_prctl() now prepares a new set of credentials, even
if it doesn't end up using it.
(9) Keyrings.
A number of changes have been made to the keyrings code:
(a) switch_uid_keyring(), copy_keys(), exit_keys() and suid_keys() have
all been dropped and built in to the credentials functions directly.
They may want separating out again later.
(b) key_alloc() and search_process_keyrings() now take a cred pointer
rather than a task pointer to specify the security context.
(c) copy_creds() gives a new thread within the same thread group a new
thread keyring if its parent had one, otherwise it discards the thread
keyring.
(d) The authorisation key now points directly to the credentials to extend
the search into rather pointing to the task that carries them.
(e) Installing thread, process or session keyrings causes a new set of
credentials to be created, even though it's not strictly necessary for
process or session keyrings (they're shared).
(10) Usermode helper.
The usermode helper code now carries a cred struct pointer in its
subprocess_info struct instead of a new session keyring pointer. This set
of credentials is derived from init_cred and installed on the new process
after it has been cloned.
call_usermodehelper_setup() allocates the new credentials and
call_usermodehelper_freeinfo() discards them if they haven't been used. A
special cred function (prepare_usermodeinfo_creds()) is provided
specifically for call_usermodehelper_setup() to call.
call_usermodehelper_setkeys() adjusts the credentials to sport the
supplied keyring as the new session keyring.
(11) SELinux.
SELinux has a number of changes, in addition to those to support the LSM
interface changes mentioned above:
(a) selinux_setprocattr() no longer does its check for whether the
current ptracer can access processes with the new SID inside the lock
that covers getting the ptracer's SID. Whilst this lock ensures that
the check is done with the ptracer pinned, the result is only valid
until the lock is released, so there's no point doing it inside the
lock.
(12) is_single_threaded().
This function has been extracted from selinux_setprocattr() and put into
a file of its own in the lib/ directory as join_session_keyring() now
wants to use it too.
The code in SELinux just checked to see whether a task shared mm_structs
with other tasks (CLONE_VM), but that isn't good enough. We really want
to know if they're part of the same thread group (CLONE_THREAD).
(13) nfsd.
The NFS server daemon now has to use the COW credentials to set the
credentials it is going to use. It really needs to pass the credentials
down to the functions it calls, but it can't do that until other patches
in this series have been applied.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: James Morris <jmorris@namei.org>
Signed-off-by: James Morris <jmorris@namei.org>
2008-11-14 10:39:23 +11:00
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2005-04-16 15:20:36 -07:00
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2013-09-24 10:35:18 +01:00
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2005-04-16 15:20:36 -07:00
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2010-04-30 14:32:39 +01:00
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2005-04-16 15:20:36 -07:00
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2013-09-24 10:35:18 +01:00
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2005-04-16 15:20:36 -07:00
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2007-10-16 23:29:46 -07:00
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2005-06-23 22:00:49 -07:00
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2005-04-16 15:20:36 -07:00
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2015-10-21 14:04:48 +01:00
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2013-10-30 11:15:24 +00:00
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2005-06-23 22:00:49 -07:00
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2009-09-14 17:26:13 +01:00
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2010-04-30 14:32:39 +01:00
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2013-09-24 10:35:18 +01:00
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[PATCH] Keys: Make request-key create an authorisation key
The attached patch makes the following changes:
(1) There's a new special key type called ".request_key_auth".
This is an authorisation key for when one process requests a key and
another process is started to construct it. This type of key cannot be
created by the user; nor can it be requested by kernel services.
Authorisation keys hold two references:
(a) Each refers to a key being constructed. When the key being
constructed is instantiated the authorisation key is revoked,
rendering it of no further use.
(b) The "authorising process". This is either:
(i) the process that called request_key(), or:
(ii) if the process that called request_key() itself had an
authorisation key in its session keyring, then the authorising
process referred to by that authorisation key will also be
referred to by the new authorisation key.
This means that the process that initiated a chain of key requests
will authorise the lot of them, and will, by default, wind up with
the keys obtained from them in its keyrings.
(2) request_key() creates an authorisation key which is then passed to
/sbin/request-key in as part of a new session keyring.
(3) When request_key() is searching for a key to hand back to the caller, if
it comes across an authorisation key in the session keyring of the
calling process, it will also search the keyrings of the process
specified therein and it will use the specified process's credentials
(fsuid, fsgid, groups) to do that rather than the calling process's
credentials.
This allows a process started by /sbin/request-key to find keys belonging
to the authorising process.
(4) A key can be read, even if the process executing KEYCTL_READ doesn't have
direct read or search permission if that key is contained within the
keyrings of a process specified by an authorisation key found within the
calling process's session keyring, and is searchable using the
credentials of the authorising process.
This allows a process started by /sbin/request-key to read keys belonging
to the authorising process.
(5) The magic KEY_SPEC_*_KEYRING key IDs when passed to KEYCTL_INSTANTIATE or
KEYCTL_NEGATE will specify a keyring of the authorising process, rather
than the process doing the instantiation.
(6) One of the process keyrings can be nominated as the default to which
request_key() should attach new keys if not otherwise specified. This is
done with KEYCTL_SET_REQKEY_KEYRING and one of the KEY_REQKEY_DEFL_*
constants. The current setting can also be read using this call.
(7) request_key() is partially interruptible. If it is waiting for another
process to finish constructing a key, it can be interrupted. This permits
a request-key cycle to be broken without recourse to rebooting.
Signed-Off-By: David Howells <dhowells@redhat.com>
Signed-Off-By: Benoit Boissinot <benoit.boissinot@ens-lyon.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 22:00:56 -07:00
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CRED: Inaugurate COW credentials
Inaugurate copy-on-write credentials management. This uses RCU to manage the
credentials pointer in the task_struct with respect to accesses by other tasks.
A process may only modify its own credentials, and so does not need locking to
access or modify its own credentials.
A mutex (cred_replace_mutex) is added to the task_struct to control the effect
of PTRACE_ATTACHED on credential calculations, particularly with respect to
execve().
With this patch, the contents of an active credentials struct may not be
changed directly; rather a new set of credentials must be prepared, modified
and committed using something like the following sequence of events:
struct cred *new = prepare_creds();
int ret = blah(new);
if (ret < 0) {
abort_creds(new);
return ret;
}
return commit_creds(new);
There are some exceptions to this rule: the keyrings pointed to by the active
credentials may be instantiated - keyrings violate the COW rule as managing
COW keyrings is tricky, given that it is possible for a task to directly alter
the keys in a keyring in use by another task.
To help enforce this, various pointers to sets of credentials, such as those in
the task_struct, are declared const. The purpose of this is compile-time
discouragement of altering credentials through those pointers. Once a set of
credentials has been made public through one of these pointers, it may not be
modified, except under special circumstances:
(1) Its reference count may incremented and decremented.
(2) The keyrings to which it points may be modified, but not replaced.
The only safe way to modify anything else is to create a replacement and commit
using the functions described in Documentation/credentials.txt (which will be
added by a later patch).
This patch and the preceding patches have been tested with the LTP SELinux
testsuite.
This patch makes several logical sets of alteration:
(1) execve().
This now prepares and commits credentials in various places in the
security code rather than altering the current creds directly.
(2) Temporary credential overrides.
do_coredump() and sys_faccessat() now prepare their own credentials and
temporarily override the ones currently on the acting thread, whilst
preventing interference from other threads by holding cred_replace_mutex
on the thread being dumped.
This will be replaced in a future patch by something that hands down the
credentials directly to the functions being called, rather than altering
the task's objective credentials.
(3) LSM interface.
A number of functions have been changed, added or removed:
(*) security_capset_check(), ->capset_check()
(*) security_capset_set(), ->capset_set()
Removed in favour of security_capset().
(*) security_capset(), ->capset()
New. This is passed a pointer to the new creds, a pointer to the old
creds and the proposed capability sets. It should fill in the new
creds or return an error. All pointers, barring the pointer to the
new creds, are now const.
(*) security_bprm_apply_creds(), ->bprm_apply_creds()
Changed; now returns a value, which will cause the process to be
killed if it's an error.
(*) security_task_alloc(), ->task_alloc_security()
Removed in favour of security_prepare_creds().
(*) security_cred_free(), ->cred_free()
New. Free security data attached to cred->security.
(*) security_prepare_creds(), ->cred_prepare()
New. Duplicate any security data attached to cred->security.
(*) security_commit_creds(), ->cred_commit()
New. Apply any security effects for the upcoming installation of new
security by commit_creds().
(*) security_task_post_setuid(), ->task_post_setuid()
Removed in favour of security_task_fix_setuid().
(*) security_task_fix_setuid(), ->task_fix_setuid()
Fix up the proposed new credentials for setuid(). This is used by
cap_set_fix_setuid() to implicitly adjust capabilities in line with
setuid() changes. Changes are made to the new credentials, rather
than the task itself as in security_task_post_setuid().
(*) security_task_reparent_to_init(), ->task_reparent_to_init()
Removed. Instead the task being reparented to init is referred
directly to init's credentials.
NOTE! This results in the loss of some state: SELinux's osid no
longer records the sid of the thread that forked it.
(*) security_key_alloc(), ->key_alloc()
(*) security_key_permission(), ->key_permission()
Changed. These now take cred pointers rather than task pointers to
refer to the security context.
(4) sys_capset().
This has been simplified and uses less locking. The LSM functions it
calls have been merged.
(5) reparent_to_kthreadd().
This gives the current thread the same credentials as init by simply using
commit_thread() to point that way.
(6) __sigqueue_alloc() and switch_uid()
__sigqueue_alloc() can't stop the target task from changing its creds
beneath it, so this function gets a reference to the currently applicable
user_struct which it then passes into the sigqueue struct it returns if
successful.
switch_uid() is now called from commit_creds(), and possibly should be
folded into that. commit_creds() should take care of protecting
__sigqueue_alloc().
(7) [sg]et[ug]id() and co and [sg]et_current_groups.
The set functions now all use prepare_creds(), commit_creds() and
abort_creds() to build and check a new set of credentials before applying
it.
security_task_set[ug]id() is called inside the prepared section. This
guarantees that nothing else will affect the creds until we've finished.
The calling of set_dumpable() has been moved into commit_creds().
Much of the functionality of set_user() has been moved into
commit_creds().
The get functions all simply access the data directly.
(8) security_task_prctl() and cap_task_prctl().
security_task_prctl() has been modified to return -ENOSYS if it doesn't
want to handle a function, or otherwise return the return value directly
rather than through an argument.
Additionally, cap_task_prctl() now prepares a new set of credentials, even
if it doesn't end up using it.
(9) Keyrings.
A number of changes have been made to the keyrings code:
(a) switch_uid_keyring(), copy_keys(), exit_keys() and suid_keys() have
all been dropped and built in to the credentials functions directly.
They may want separating out again later.
(b) key_alloc() and search_process_keyrings() now take a cred pointer
rather than a task pointer to specify the security context.
(c) copy_creds() gives a new thread within the same thread group a new
thread keyring if its parent had one, otherwise it discards the thread
keyring.
(d) The authorisation key now points directly to the credentials to extend
the search into rather pointing to the task that carries them.
(e) Installing thread, process or session keyrings causes a new set of
credentials to be created, even though it's not strictly necessary for
process or session keyrings (they're shared).
(10) Usermode helper.
The usermode helper code now carries a cred struct pointer in its
subprocess_info struct instead of a new session keyring pointer. This set
of credentials is derived from init_cred and installed on the new process
after it has been cloned.
call_usermodehelper_setup() allocates the new credentials and
call_usermodehelper_freeinfo() discards them if they haven't been used. A
special cred function (prepare_usermodeinfo_creds()) is provided
specifically for call_usermodehelper_setup() to call.
call_usermodehelper_setkeys() adjusts the credentials to sport the
supplied keyring as the new session keyring.
(11) SELinux.
SELinux has a number of changes, in addition to those to support the LSM
interface changes mentioned above:
(a) selinux_setprocattr() no longer does its check for whether the
current ptracer can access processes with the new SID inside the lock
that covers getting the ptracer's SID. Whilst this lock ensures that
the check is done with the ptracer pinned, the result is only valid
until the lock is released, so there's no point doing it inside the
lock.
(12) is_single_threaded().
This function has been extracted from selinux_setprocattr() and put into
a file of its own in the lib/ directory as join_session_keyring() now
wants to use it too.
The code in SELinux just checked to see whether a task shared mm_structs
with other tasks (CLONE_VM), but that isn't good enough. We really want
to know if they're part of the same thread group (CLONE_THREAD).
(13) nfsd.
The NFS server daemon now has to use the COW credentials to set the
credentials it is going to use. It really needs to pass the credentials
down to the functions it calls, but it can't do that until other patches
in this series have been applied.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: James Morris <jmorris@namei.org>
Signed-off-by: James Morris <jmorris@namei.org>
2008-11-14 10:39:23 +11:00
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2005-04-16 15:20:36 -07:00
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2007-10-16 23:29:46 -07:00
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2005-04-16 15:20:36 -07:00
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KEYS: potential uninitialized variable
commit 38327424b40bcebe2de92d07312c89360ac9229a upstream.
If __key_link_begin() failed then "edit" would be uninitialized. I've
added a check to fix that.
This allows a random user to crash the kernel, though it's quite
difficult to achieve. There are three ways it can be done as the user
would have to cause an error to occur in __key_link():
(1) Cause the kernel to run out of memory. In practice, this is difficult
to achieve without ENOMEM cropping up elsewhere and aborting the
attempt.
(2) Revoke the destination keyring between the keyring ID being looked up
and it being tested for revocation. In practice, this is difficult to
time correctly because the KEYCTL_REJECT function can only be used
from the request-key upcall process. Further, users can only make use
of what's in /sbin/request-key.conf, though this does including a
rejection debugging test - which means that the destination keyring
has to be the caller's session keyring in practice.
(3) Have just enough key quota available to create a key, a new session
keyring for the upcall and a link in the session keyring, but not then
sufficient quota to create a link in the nominated destination keyring
so that it fails with EDQUOT.
The bug can be triggered using option (3) above using something like the
following:
echo 80 >/proc/sys/kernel/keys/root_maxbytes
keyctl request2 user debug:fred negate @t
The above sets the quota to something much lower (80) to make the bug
easier to trigger, but this is dependent on the system. Note also that
the name of the keyring created contains a random number that may be
between 1 and 10 characters in size, so may throw the test off by
changing the amount of quota used.
Assuming the failure occurs, something like the following will be seen:
kfree_debugcheck: out of range ptr 6b6b6b6b6b6b6b68h
------------[ cut here ]------------
kernel BUG at ../mm/slab.c:2821!
...
RIP: 0010:[<ffffffff811600f9>] kfree_debugcheck+0x20/0x25
RSP: 0018:ffff8804014a7de8 EFLAGS: 00010092
RAX: 0000000000000034 RBX: 6b6b6b6b6b6b6b68 RCX: 0000000000000000
RDX: 0000000000040001 RSI: 00000000000000f6 RDI: 0000000000000300
RBP: ffff8804014a7df0 R08: 0000000000000001 R09: 0000000000000000
R10: ffff8804014a7e68 R11: 0000000000000054 R12: 0000000000000202
R13: ffffffff81318a66 R14: 0000000000000000 R15: 0000000000000001
...
Call Trace:
kfree+0xde/0x1bc
assoc_array_cancel_edit+0x1f/0x36
__key_link_end+0x55/0x63
key_reject_and_link+0x124/0x155
keyctl_reject_key+0xb6/0xe0
keyctl_negate_key+0x10/0x12
SyS_keyctl+0x9f/0xe7
do_syscall_64+0x63/0x13a
entry_SYSCALL64_slow_path+0x25/0x25
Fixes: f70e2e06196a ('KEYS: Do preallocation for __key_link()')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-06-16 15:48:57 +01:00
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2013-09-24 10:35:18 +01:00
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2005-04-16 15:20:36 -07:00
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2007-10-16 23:29:46 -07:00
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2005-04-16 15:20:36 -07:00
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2010-04-30 14:32:39 +01:00
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2011-01-20 16:38:27 +00:00
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2011-03-07 15:06:09 +00:00
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2005-04-16 15:20:36 -07:00
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2011-01-20 16:38:33 +00:00
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2005-04-16 15:20:36 -07:00
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2012-08-20 14:51:24 -07:00
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2005-04-16 15:20:36 -07:00
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2011-01-20 16:38:27 +00:00
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2005-04-16 15:20:36 -07:00
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2011-01-20 16:38:33 +00:00
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2005-04-16 15:20:36 -07:00
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2011-01-20 16:38:33 +00:00
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2005-04-16 15:20:36 -07:00
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2011-01-20 16:38:33 +00:00
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2009-09-02 09:13:45 +01:00
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2005-04-16 15:20:36 -07:00
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2013-09-24 10:35:16 +01:00
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2005-04-16 15:20:36 -07:00
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2011-01-20 16:38:33 +00:00
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2005-04-16 15:20:36 -07:00
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2011-01-20 16:38:27 +00:00
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2005-04-16 15:20:36 -07:00
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2011-01-20 16:38:33 +00:00
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2005-04-16 15:20:36 -07:00
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2011-01-20 16:38:33 +00:00
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2005-04-16 15:20:36 -07:00
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2011-01-20 16:38:27 +00:00
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2005-04-16 15:20:36 -07:00
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2012-02-24 14:14:50 -05:00
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2005-04-16 15:20:36 -07:00
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2011-01-20 16:38:33 +00:00
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2005-04-16 15:20:36 -07:00
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2011-01-20 16:38:27 +00:00
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2005-04-16 15:20:36 -07:00
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2011-01-20 16:38:33 +00:00
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2005-04-16 15:20:36 -07:00
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2005-09-28 17:03:15 +01:00
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2012-09-13 13:06:29 +01:00
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2005-04-16 15:20:36 -07:00
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2005-09-28 17:03:15 +01:00
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2005-04-16 15:20:36 -07:00
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2014-03-14 17:44:49 +00:00
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2005-10-30 15:02:44 -08:00
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2005-04-16 15:20:36 -07:00
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2012-09-13 13:06:29 +01:00
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2005-06-23 22:00:49 -07:00
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2005-04-16 15:20:36 -07:00
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2005-06-23 22:00:49 -07:00
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2005-04-16 15:20:36 -07:00
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2005-09-28 17:03:15 +01:00
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2005-04-16 15:20:36 -07:00
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2005-09-28 17:03:15 +01:00
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2005-04-16 15:20:36 -07:00
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2005-09-28 17:03:15 +01:00
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2005-04-16 15:20:36 -07:00
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2011-01-20 16:38:27 +00:00
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2005-04-16 15:20:36 -07:00
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2011-01-20 16:38:33 +00:00
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2005-04-16 15:20:36 -07:00
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2005-09-28 17:03:15 +01:00
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2008-04-29 01:01:28 -07:00
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2006-06-26 00:24:50 -07:00
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2005-04-16 15:20:36 -07:00
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2013-09-24 10:35:15 +01:00
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2012-09-13 13:06:29 +01:00
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2013-09-24 10:35:18 +01:00
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CRED: Inaugurate COW credentials
Inaugurate copy-on-write credentials management. This uses RCU to manage the
credentials pointer in the task_struct with respect to accesses by other tasks.
A process may only modify its own credentials, and so does not need locking to
access or modify its own credentials.
A mutex (cred_replace_mutex) is added to the task_struct to control the effect
of PTRACE_ATTACHED on credential calculations, particularly with respect to
execve().
With this patch, the contents of an active credentials struct may not be
changed directly; rather a new set of credentials must be prepared, modified
and committed using something like the following sequence of events:
struct cred *new = prepare_creds();
int ret = blah(new);
if (ret < 0) {
abort_creds(new);
return ret;
}
return commit_creds(new);
There are some exceptions to this rule: the keyrings pointed to by the active
credentials may be instantiated - keyrings violate the COW rule as managing
COW keyrings is tricky, given that it is possible for a task to directly alter
the keys in a keyring in use by another task.
To help enforce this, various pointers to sets of credentials, such as those in
the task_struct, are declared const. The purpose of this is compile-time
discouragement of altering credentials through those pointers. Once a set of
credentials has been made public through one of these pointers, it may not be
modified, except under special circumstances:
(1) Its reference count may incremented and decremented.
(2) The keyrings to which it points may be modified, but not replaced.
The only safe way to modify anything else is to create a replacement and commit
using the functions described in Documentation/credentials.txt (which will be
added by a later patch).
This patch and the preceding patches have been tested with the LTP SELinux
testsuite.
This patch makes several logical sets of alteration:
(1) execve().
This now prepares and commits credentials in various places in the
security code rather than altering the current creds directly.
(2) Temporary credential overrides.
do_coredump() and sys_faccessat() now prepare their own credentials and
temporarily override the ones currently on the acting thread, whilst
preventing interference from other threads by holding cred_replace_mutex
on the thread being dumped.
This will be replaced in a future patch by something that hands down the
credentials directly to the functions being called, rather than altering
the task's objective credentials.
(3) LSM interface.
A number of functions have been changed, added or removed:
(*) security_capset_check(), ->capset_check()
(*) security_capset_set(), ->capset_set()
Removed in favour of security_capset().
(*) security_capset(), ->capset()
New. This is passed a pointer to the new creds, a pointer to the old
creds and the proposed capability sets. It should fill in the new
creds or return an error. All pointers, barring the pointer to the
new creds, are now const.
(*) security_bprm_apply_creds(), ->bprm_apply_creds()
Changed; now returns a value, which will cause the process to be
killed if it's an error.
(*) security_task_alloc(), ->task_alloc_security()
Removed in favour of security_prepare_creds().
(*) security_cred_free(), ->cred_free()
New. Free security data attached to cred->security.
(*) security_prepare_creds(), ->cred_prepare()
New. Duplicate any security data attached to cred->security.
(*) security_commit_creds(), ->cred_commit()
New. Apply any security effects for the upcoming installation of new
security by commit_creds().
(*) security_task_post_setuid(), ->task_post_setuid()
Removed in favour of security_task_fix_setuid().
(*) security_task_fix_setuid(), ->task_fix_setuid()
Fix up the proposed new credentials for setuid(). This is used by
cap_set_fix_setuid() to implicitly adjust capabilities in line with
setuid() changes. Changes are made to the new credentials, rather
than the task itself as in security_task_post_setuid().
(*) security_task_reparent_to_init(), ->task_reparent_to_init()
Removed. Instead the task being reparented to init is referred
directly to init's credentials.
NOTE! This results in the loss of some state: SELinux's osid no
longer records the sid of the thread that forked it.
(*) security_key_alloc(), ->key_alloc()
(*) security_key_permission(), ->key_permission()
Changed. These now take cred pointers rather than task pointers to
refer to the security context.
(4) sys_capset().
This has been simplified and uses less locking. The LSM functions it
calls have been merged.
(5) reparent_to_kthreadd().
This gives the current thread the same credentials as init by simply using
commit_thread() to point that way.
(6) __sigqueue_alloc() and switch_uid()
__sigqueue_alloc() can't stop the target task from changing its creds
beneath it, so this function gets a reference to the currently applicable
user_struct which it then passes into the sigqueue struct it returns if
successful.
switch_uid() is now called from commit_creds(), and possibly should be
folded into that. commit_creds() should take care of protecting
__sigqueue_alloc().
(7) [sg]et[ug]id() and co and [sg]et_current_groups.
The set functions now all use prepare_creds(), commit_creds() and
abort_creds() to build and check a new set of credentials before applying
it.
security_task_set[ug]id() is called inside the prepared section. This
guarantees that nothing else will affect the creds until we've finished.
The calling of set_dumpable() has been moved into commit_creds().
Much of the functionality of set_user() has been moved into
commit_creds().
The get functions all simply access the data directly.
(8) security_task_prctl() and cap_task_prctl().
security_task_prctl() has been modified to return -ENOSYS if it doesn't
want to handle a function, or otherwise return the return value directly
rather than through an argument.
Additionally, cap_task_prctl() now prepares a new set of credentials, even
if it doesn't end up using it.
(9) Keyrings.
A number of changes have been made to the keyrings code:
(a) switch_uid_keyring(), copy_keys(), exit_keys() and suid_keys() have
all been dropped and built in to the credentials functions directly.
They may want separating out again later.
(b) key_alloc() and search_process_keyrings() now take a cred pointer
rather than a task pointer to specify the security context.
(c) copy_creds() gives a new thread within the same thread group a new
thread keyring if its parent had one, otherwise it discards the thread
keyring.
(d) The authorisation key now points directly to the credentials to extend
the search into rather pointing to the task that carries them.
(e) Installing thread, process or session keyrings causes a new set of
credentials to be created, even though it's not strictly necessary for
process or session keyrings (they're shared).
(10) Usermode helper.
The usermode helper code now carries a cred struct pointer in its
subprocess_info struct instead of a new session keyring pointer. This set
of credentials is derived from init_cred and installed on the new process
after it has been cloned.
call_usermodehelper_setup() allocates the new credentials and
call_usermodehelper_freeinfo() discards them if they haven't been used. A
special cred function (prepare_usermodeinfo_creds()) is provided
specifically for call_usermodehelper_setup() to call.
call_usermodehelper_setkeys() adjusts the credentials to sport the
supplied keyring as the new session keyring.
(11) SELinux.
SELinux has a number of changes, in addition to those to support the LSM
interface changes mentioned above:
(a) selinux_setprocattr() no longer does its check for whether the
current ptracer can access processes with the new SID inside the lock
that covers getting the ptracer's SID. Whilst this lock ensures that
the check is done with the ptracer pinned, the result is only valid
until the lock is released, so there's no point doing it inside the
lock.
(12) is_single_threaded().
This function has been extracted from selinux_setprocattr() and put into
a file of its own in the lib/ directory as join_session_keyring() now
wants to use it too.
The code in SELinux just checked to see whether a task shared mm_structs
with other tasks (CLONE_VM), but that isn't good enough. We really want
to know if they're part of the same thread group (CLONE_THREAD).
(13) nfsd.
The NFS server daemon now has to use the COW credentials to set the
credentials it is going to use. It really needs to pass the credentials
down to the functions it calls, but it can't do that until other patches
in this series have been applied.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: James Morris <jmorris@namei.org>
Signed-off-by: James Morris <jmorris@namei.org>
2008-11-14 10:39:23 +11:00
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2005-09-28 17:03:15 +01:00
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2005-04-16 15:20:36 -07:00
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2013-09-24 10:35:15 +01:00
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2005-09-28 17:03:15 +01:00
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2005-04-16 15:20:36 -07:00
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2005-09-28 17:03:15 +01:00
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2014-09-16 17:36:06 +01:00
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2013-09-24 10:35:15 +01:00
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2012-09-13 13:06:29 +01:00
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2005-04-16 15:20:36 -07:00
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2005-09-28 17:03:15 +01:00
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2006-04-10 15:15:21 +01:00
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2012-09-13 13:06:29 +01:00
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2013-09-24 10:35:15 +01:00
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2013-08-30 16:07:37 +01:00
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2014-07-18 18:56:34 +01:00
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2013-09-24 10:35:15 +01:00
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2012-09-13 13:06:29 +01:00
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2014-07-18 18:56:34 +01:00
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2012-09-13 13:06:29 +01:00
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2013-09-24 10:35:15 +01:00
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2012-09-13 13:06:29 +01:00
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2013-09-24 10:35:15 +01:00
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2012-09-13 13:06:29 +01:00
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2013-09-24 10:35:15 +01:00
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2006-04-10 15:15:21 +01:00
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2013-08-30 16:07:37 +01:00
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2013-09-24 10:35:18 +01:00
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2012-09-13 13:06:29 +01:00
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2005-09-28 17:03:15 +01:00
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2014-03-14 17:44:49 +00:00
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2005-10-30 15:02:44 -08:00
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2012-09-13 13:06:29 +01:00
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2005-10-30 15:02:44 -08:00
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2005-09-28 17:03:15 +01:00
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2006-03-25 03:06:52 -08:00
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2005-04-16 15:20:36 -07:00
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2013-09-24 10:35:15 +01:00
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2013-09-24 10:35:18 +01:00
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2006-03-25 03:06:52 -08:00
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2005-04-16 15:20:36 -07:00
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2008-04-29 01:01:28 -07:00
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2012-10-02 19:24:56 +01:00
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2005-04-16 15:20:36 -07:00
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2013-09-24 10:35:15 +01:00
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2012-10-02 19:24:56 +01:00
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2005-04-16 15:20:36 -07:00
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2013-09-24 10:35:15 +01:00
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2012-10-02 19:24:56 +01:00
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2008-04-29 01:01:28 -07:00
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2005-04-16 15:20:36 -07:00
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2013-09-24 10:35:15 +01:00
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2005-04-16 15:20:36 -07:00
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2008-02-07 00:15:26 -08:00
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2012-09-13 13:06:29 +01:00
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2005-04-16 15:20:36 -07:00
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2013-09-24 10:35:18 +01:00
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2005-04-16 15:20:36 -07:00
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2005-09-28 17:03:15 +01:00
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2012-09-13 13:06:29 +01:00
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2005-04-16 15:20:36 -07:00
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2005-09-28 17:03:15 +01:00
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2012-09-13 13:06:29 +01:00
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2013-09-24 10:35:18 +01:00
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2012-09-13 13:06:29 +01:00
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2013-09-24 10:35:15 +01:00
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2012-09-13 13:06:29 +01:00
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2013-09-24 10:35:15 +01:00
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2012-09-13 13:06:29 +01:00
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2005-09-28 17:03:15 +01:00
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2005-04-16 15:20:36 -07:00
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2013-09-24 10:35:18 +01:00
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2005-04-16 15:20:36 -07:00
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2012-09-13 13:06:29 +01:00
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2011-01-20 16:38:27 +00:00
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2005-04-16 15:20:36 -07:00
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2011-01-20 16:38:33 +00:00
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2005-04-16 15:20:36 -07:00
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2005-09-28 17:03:15 +01:00
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2005-04-16 15:20:36 -07:00
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2012-09-13 13:06:29 +01:00
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2005-09-28 17:03:15 +01:00
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2005-04-16 15:20:36 -07:00
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2014-03-14 17:44:49 +00:00
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2005-10-30 15:02:44 -08:00
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2005-04-16 15:20:36 -07:00
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2012-09-13 13:06:29 +01:00
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2005-04-16 15:20:36 -07:00
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2012-09-13 13:06:29 +01:00
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2014-07-18 18:56:34 +01:00
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2012-09-13 13:06:29 +01:00
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2012-09-13 13:06:29 +01:00
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2014-07-18 18:56:34 +01:00
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2012-09-13 13:06:29 +01:00
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2005-04-16 15:20:36 -07:00
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2011-01-20 16:38:27 +00:00
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2005-04-16 15:20:36 -07:00
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2011-01-20 16:38:33 +00:00
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2009-09-02 09:14:00 +01:00
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2009-09-02 09:14:00 +01:00
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2009-09-14 17:26:13 +01:00
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2009-09-02 09:14:00 +01:00
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2011-01-20 16:38:27 +00:00
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2012-05-11 10:56:56 +01:00
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2015-10-21 14:04:48 +01:00
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2014-07-18 18:56:34 +01:00
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2011-01-20 16:38:33 +00:00
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2005-04-16 15:20:36 -07:00
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2011-11-16 11:15:54 +00:00
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2005-04-16 15:20:36 -07:00
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2012-05-11 10:56:56 +01:00
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2005-04-16 15:20:36 -07:00
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2011-01-20 16:38:33 +00:00
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2005-04-16 15:20:36 -07:00
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2011-01-20 16:38:27 +00:00
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2005-04-16 15:20:36 -07:00
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2011-01-20 16:38:33 +00:00
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2005-04-16 15:20:36 -07:00
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KEYS: Correctly destroy key payloads when their keytype is removed
unregister_key_type() has code to mark a key as dead and make it unavailable in
one loop and then destroy all those unavailable key payloads in the next loop.
However, the loop to mark keys dead renders the key undetectable to the second
loop by changing the key type pointer also.
Fix this by the following means:
(1) The key code has two garbage collectors: one deletes unreferenced keys and
the other alters keyrings to delete links to old dead, revoked and expired
keys. They can end up holding each other up as both want to scan the key
serial tree under spinlock. Combine these into a single routine.
(2) Move the dead key marking, dead link removal and dead key removal into the
garbage collector as a three phase process running over the three cycles
of the normal garbage collection procedure. This is tracked by the
KEY_GC_REAPING_DEAD_1, _2 and _3 state flags.
unregister_key_type() then just unlinks the key type from the list, wakes
up the garbage collector and waits for the third phase to complete.
(3) Downgrade the key types sem in unregister_key_type() once it has deleted
the key type from the list so that it doesn't block the keyctl() syscall.
(4) Dead keys that cannot be simply removed in the third phase have their
payloads destroyed with the key's semaphore write-locked to prevent
interference by the keyctl() syscall. There should be no in-kernel users
of dead keys of that type by the point of unregistration, though keyctl()
may be holding a reference.
(5) Only perform timer recalculation in the GC if the timer actually expired.
If it didn't, we'll get another cycle when it goes off - and if the key
that actually triggered it has been removed, it's not a problem.
(6) Only garbage collect link if the timer expired or if we're doing dead key
clean up phase 2.
(7) As only key_garbage_collector() is permitted to use rb_erase() on the key
serial tree, it doesn't need to revalidate its cursor after dropping the
spinlock as the node the cursor points to must still exist in the tree.
(8) Drop the spinlock in the GC if there is contention on it or if we need to
reschedule. After dealing with that, get the spinlock again and resume
scanning.
This has been tested in the following ways:
(1) Run the keyutils testsuite against it.
(2) Using the AF_RXRPC and RxKAD modules to test keytype removal:
Load the rxrpc_s key type:
# insmod /tmp/af-rxrpc.ko
# insmod /tmp/rxkad.ko
Create a key (http://people.redhat.com/~dhowells/rxrpc/listen.c):
# /tmp/listen &
[1] 8173
Find the key:
# grep rxrpc_s /proc/keys
091086e1 I--Q-- 1 perm 39390000 0 0 rxrpc_s 52:2
Link it to a session keyring, preferably one with a higher serial number:
# keyctl link 0x20e36251 @s
Kill the process (the key should remain as it's linked to another place):
# fg
/tmp/listen
^C
Remove the key type:
rmmod rxkad
rmmod af-rxrpc
This can be made a more effective test by altering the following part of
the patch:
if (unlikely(gc_state & KEY_GC_REAPING_DEAD_2)) {
/* Make sure everyone revalidates their keys if we marked a
* bunch as being dead and make sure all keyring ex-payloads
* are destroyed.
*/
kdebug("dead sync");
synchronize_rcu();
To call synchronize_rcu() in GC phase 1 instead. That causes that the
keyring's old payload content to hang around longer until it's RCU
destroyed - which usually happens after GC phase 3 is complete. This
allows the destroy_dead_key branch to be tested.
Reported-by: Benjamin Coddington <bcodding@gmail.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>
2011-08-22 14:09:36 +01:00
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2012-05-11 10:56:56 +01:00
|
|
|
|
KEYS: Correctly destroy key payloads when their keytype is removed
unregister_key_type() has code to mark a key as dead and make it unavailable in
one loop and then destroy all those unavailable key payloads in the next loop.
However, the loop to mark keys dead renders the key undetectable to the second
loop by changing the key type pointer also.
Fix this by the following means:
(1) The key code has two garbage collectors: one deletes unreferenced keys and
the other alters keyrings to delete links to old dead, revoked and expired
keys. They can end up holding each other up as both want to scan the key
serial tree under spinlock. Combine these into a single routine.
(2) Move the dead key marking, dead link removal and dead key removal into the
garbage collector as a three phase process running over the three cycles
of the normal garbage collection procedure. This is tracked by the
KEY_GC_REAPING_DEAD_1, _2 and _3 state flags.
unregister_key_type() then just unlinks the key type from the list, wakes
up the garbage collector and waits for the third phase to complete.
(3) Downgrade the key types sem in unregister_key_type() once it has deleted
the key type from the list so that it doesn't block the keyctl() syscall.
(4) Dead keys that cannot be simply removed in the third phase have their
payloads destroyed with the key's semaphore write-locked to prevent
interference by the keyctl() syscall. There should be no in-kernel users
of dead keys of that type by the point of unregistration, though keyctl()
may be holding a reference.
(5) Only perform timer recalculation in the GC if the timer actually expired.
If it didn't, we'll get another cycle when it goes off - and if the key
that actually triggered it has been removed, it's not a problem.
(6) Only garbage collect link if the timer expired or if we're doing dead key
clean up phase 2.
(7) As only key_garbage_collector() is permitted to use rb_erase() on the key
serial tree, it doesn't need to revalidate its cursor after dropping the
spinlock as the node the cursor points to must still exist in the tree.
(8) Drop the spinlock in the GC if there is contention on it or if we need to
reschedule. After dealing with that, get the spinlock again and resume
scanning.
This has been tested in the following ways:
(1) Run the keyutils testsuite against it.
(2) Using the AF_RXRPC and RxKAD modules to test keytype removal:
Load the rxrpc_s key type:
# insmod /tmp/af-rxrpc.ko
# insmod /tmp/rxkad.ko
Create a key (http://people.redhat.com/~dhowells/rxrpc/listen.c):
# /tmp/listen &
[1] 8173
Find the key:
# grep rxrpc_s /proc/keys
091086e1 I--Q-- 1 perm 39390000 0 0 rxrpc_s 52:2
Link it to a session keyring, preferably one with a higher serial number:
# keyctl link 0x20e36251 @s
Kill the process (the key should remain as it's linked to another place):
# fg
/tmp/listen
^C
Remove the key type:
rmmod rxkad
rmmod af-rxrpc
This can be made a more effective test by altering the following part of
the patch:
if (unlikely(gc_state & KEY_GC_REAPING_DEAD_2)) {
/* Make sure everyone revalidates their keys if we marked a
* bunch as being dead and make sure all keyring ex-payloads
* are destroyed.
*/
kdebug("dead sync");
synchronize_rcu();
To call synchronize_rcu() in GC phase 1 instead. That causes that the
keyring's old payload content to hang around longer until it's RCU
destroyed - which usually happens after GC phase 3 is complete. This
allows the destroy_dead_key branch to be tested.
Reported-by: Benjamin Coddington <bcodding@gmail.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>
2011-08-22 14:09:36 +01:00
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2011-01-20 16:38:27 +00:00
|
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|
2005-04-16 15:20:36 -07:00
|
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2011-01-20 16:38:33 +00:00
|
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2005-04-16 15:20:36 -07:00
|
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2007-07-20 10:11:58 +09:00
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2005-04-16 15:20:36 -07:00
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2012-01-17 16:09:11 -05:00
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2005-04-16 15:20:36 -07:00
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2011-01-20 16:38:27 +00:00
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