2005-04-16 15:20:36 -07:00
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2009-04-02 16:57:20 -07:00
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2005-04-16 15:20:36 -07:00
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2011-07-23 10:39:29 -07:00
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2005-04-16 15:20:36 -07:00
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2011-07-23 10:39:29 -07:00
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2009-12-11 14:23:44 -08:00
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2009-09-11 10:28:47 +02:00
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2011-10-31 17:11:20 -07:00
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2005-04-16 15:20:36 -07:00
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2009-09-23 15:56:56 -07:00
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2005-04-16 15:20:36 -07:00
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2010-11-11 14:05:18 -08:00
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2005-04-16 15:20:36 -07:00
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2014-01-20 17:34:13 +00:00
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kexec: add sysctl to disable kexec_load
For general-purpose (i.e. distro) kernel builds it makes sense to build
with CONFIG_KEXEC to allow end users to choose what kind of things they
want to do with kexec. However, in the face of trying to lock down a
system with such a kernel, there needs to be a way to disable kexec_load
(much like module loading can be disabled). Without this, it is too easy
for the root user to modify kernel memory even when CONFIG_STRICT_DEVMEM
and modules_disabled are set. With this change, it is still possible to
load an image for use later, then disable kexec_load so the image (or lack
of image) can't be altered.
The intention is for using this in environments where "perfect"
enforcement is hard. Without a verified boot, along with verified
modules, and along with verified kexec, this is trying to give a system a
better chance to defend itself (or at least grow the window of
discoverability) against attack in the face of a privilege escalation.
In my mind, I consider several boot scenarios:
1) Verified boot of read-only verified root fs loading fd-based
verification of kexec images.
2) Secure boot of writable root fs loading signed kexec images.
3) Regular boot loading kexec (e.g. kcrash) image early and locking it.
4) Regular boot with no control of kexec image at all.
1 and 2 don't exist yet, but will soon once the verified kexec series has
landed. 4 is the state of things now. The gap between 2 and 4 is too
large, so this change creates scenario 3, a middle-ground above 4 when 2
and 1 are not possible for a system.
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-01-23 15:55:59 -08:00
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kptr_restrict for hiding kernel pointers from unprivileged users
Add the %pK printk format specifier and the /proc/sys/kernel/kptr_restrict
sysctl.
The %pK format specifier is designed to hide exposed kernel pointers,
specifically via /proc interfaces. Exposing these pointers provides an
easy target for kernel write vulnerabilities, since they reveal the
locations of writable structures containing easily triggerable function
pointers. The behavior of %pK depends on the kptr_restrict sysctl.
If kptr_restrict is set to 0, no deviation from the standard %p behavior
occurs. If kptr_restrict is set to 1, the default, if the current user
(intended to be a reader via seq_printf(), etc.) does not have CAP_SYSLOG
(currently in the LSM tree), kernel pointers using %pK are printed as 0's.
If kptr_restrict is set to 2, kernel pointers using %pK are printed as
0's regardless of privileges. Replacing with 0's was chosen over the
default "(null)", which cannot be parsed by userland %p, which expects
"(nil)".
[akpm@linux-foundation.org: check for IRQ context when !kptr_restrict, save an indent level, s/WARN/WARN_ONCE/]
[akpm@linux-foundation.org: coding-style fixup]
[randy.dunlap@oracle.com: fix kernel/sysctl.c warning]
Signed-off-by: Dan Rosenberg <drosenberg@vsecurity.com>
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Cc: James Morris <jmorris@namei.org>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Thomas Graf <tgraf@infradead.org>
Cc: Eugene Teo <eugeneteo@kernel.org>
Cc: Kees Cook <kees.cook@canonical.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: David S. Miller <davem@davemloft.net>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Eric Paris <eparis@parisplace.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-01-12 16:59:41 -08:00
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2006-12-07 02:14:11 +01:00
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2005-04-16 15:20:36 -07:00
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2008-02-13 15:03:32 -08:00
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2009-04-02 15:49:29 -07:00
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2013-01-04 15:34:50 -08:00
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2005-04-16 15:20:36 -07:00
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2009-04-02 16:57:20 -07:00
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2005-04-16 15:20:36 -07:00
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2011-07-23 10:39:29 -07:00
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2011-11-29 15:08:36 +09:00
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2005-04-16 15:20:36 -07:00
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2011-07-23 10:39:29 -07:00
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2008-02-09 23:24:08 +01:00
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2005-04-16 15:20:36 -07:00
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2013-01-04 15:34:50 -08:00
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2005-04-16 15:20:36 -07:00
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2013-01-04 15:34:50 -08:00
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2011-07-26 16:08:48 -07:00
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2005-04-16 15:20:36 -07:00
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2014-06-23 13:22:05 -07:00
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2005-04-16 15:20:36 -07:00
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sysctl: allow for strict write position handling
When writing to a sysctl string, each write, regardless of VFS position,
begins writing the string from the start. This means the contents of
the last write to the sysctl controls the string contents instead of the
first:
open("/proc/sys/kernel/modprobe", O_WRONLY) = 1
write(1, "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"..., 4096) = 4096
write(1, "/bin/true", 9) = 9
close(1) = 0
$ cat /proc/sys/kernel/modprobe
/bin/true
Expected behaviour would be to have the sysctl be "AAAA..." capped at
maxlen (in this case KMOD_PATH_LEN: 256), instead of truncating to the
contents of the second write. Similarly, multiple short writes would
not append to the sysctl.
The old behavior is unlike regular POSIX files enough that doing audits
of software that interact with sysctls can end up in unexpected or
dangerous situations. For example, "as long as the input starts with a
trusted path" turns out to be an insufficient filter, as what must also
happen is for the input to be entirely contained in a single write
syscall -- not a common consideration, especially for high level tools.
This provides kernel.sysctl_writes_strict as a way to make this behavior
act in a less surprising manner for strings, and disallows non-zero file
position when writing numeric sysctls (similar to what is already done
when reading from non-zero file positions). For now, the default (0) is
to warn about non-zero file position use, but retain the legacy
behavior. Setting this to -1 disables the warning, and setting this to
1 enables the file position respecting behavior.
[akpm@linux-foundation.org: fix build]
[akpm@linux-foundation.org: move misplaced hunk, per Randy]
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-06 14:37:19 -07:00
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2005-04-16 15:20:36 -07:00
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2009-04-02 16:57:20 -07:00
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2013-05-17 10:31:20 +08:00
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2005-04-16 15:20:36 -07:00
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2011-07-23 10:39:29 -07:00
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2005-04-16 15:20:36 -07:00
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2009-12-11 14:23:44 -08:00
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2009-09-11 10:28:47 +02:00
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2011-10-31 17:11:20 -07:00
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2005-04-16 15:20:36 -07:00
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2006-10-11 01:21:57 -07:00
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2005-04-16 15:20:36 -07:00
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2013-09-11 14:24:32 -07:00
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2014-10-13 15:53:35 -07:00
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2005-04-16 15:20:36 -07:00
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2012-10-04 17:15:25 -07:00
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2005-04-16 15:20:36 -07:00
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2011-05-26 16:25:46 -07:00
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2005-04-16 15:20:36 -07:00
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2006-10-11 01:21:57 -07:00
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2005-04-16 15:20:36 -07:00
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2009-09-23 15:56:56 -07:00
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2011-07-23 10:39:29 -07:00
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2009-09-23 15:56:56 -07:00
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2005-04-16 15:20:36 -07:00
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2010-11-11 14:05:18 -08:00
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2011-07-23 10:39:29 -07:00
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2010-12-08 15:19:01 +00:00
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2010-11-11 14:05:18 -08:00
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2011-07-23 10:39:29 -07:00
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2010-11-11 14:05:18 -08:00
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2005-04-16 15:20:36 -07:00
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2014-01-20 17:34:13 +00:00
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2014-04-07 15:38:57 -07:00
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2014-01-20 17:34:13 +00:00
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2014-01-27 09:00:57 +00:00
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2014-01-20 17:34:13 +00:00
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2014-01-27 09:00:57 +00:00
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2014-01-20 17:34:13 +00:00
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kexec: add sysctl to disable kexec_load
For general-purpose (i.e. distro) kernel builds it makes sense to build
with CONFIG_KEXEC to allow end users to choose what kind of things they
want to do with kexec. However, in the face of trying to lock down a
system with such a kernel, there needs to be a way to disable kexec_load
(much like module loading can be disabled). Without this, it is too easy
for the root user to modify kernel memory even when CONFIG_STRICT_DEVMEM
and modules_disabled are set. With this change, it is still possible to
load an image for use later, then disable kexec_load so the image (or lack
of image) can't be altered.
The intention is for using this in environments where "perfect"
enforcement is hard. Without a verified boot, along with verified
modules, and along with verified kexec, this is trying to give a system a
better chance to defend itself (or at least grow the window of
discoverability) against attack in the face of a privilege escalation.
In my mind, I consider several boot scenarios:
1) Verified boot of read-only verified root fs loading fd-based
verification of kexec images.
2) Secure boot of writable root fs loading signed kexec images.
3) Regular boot loading kexec (e.g. kcrash) image early and locking it.
4) Regular boot with no control of kexec image at all.
1 and 2 don't exist yet, but will soon once the verified kexec series has
landed. 4 is the state of things now. The gap between 2 and 4 is too
large, so this change creates scenario 3, a middle-ground above 4 when 2
and 1 are not possible for a system.
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-01-23 15:55:59 -08:00
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kptr_restrict for hiding kernel pointers from unprivileged users
Add the %pK printk format specifier and the /proc/sys/kernel/kptr_restrict
sysctl.
The %pK format specifier is designed to hide exposed kernel pointers,
specifically via /proc interfaces. Exposing these pointers provides an
easy target for kernel write vulnerabilities, since they reveal the
locations of writable structures containing easily triggerable function
pointers. The behavior of %pK depends on the kptr_restrict sysctl.
If kptr_restrict is set to 0, no deviation from the standard %p behavior
occurs. If kptr_restrict is set to 1, the default, if the current user
(intended to be a reader via seq_printf(), etc.) does not have CAP_SYSLOG
(currently in the LSM tree), kernel pointers using %pK are printed as 0's.
If kptr_restrict is set to 2, kernel pointers using %pK are printed as
0's regardless of privileges. Replacing with 0's was chosen over the
default "(null)", which cannot be parsed by userland %p, which expects
"(nil)".
[akpm@linux-foundation.org: check for IRQ context when !kptr_restrict, save an indent level, s/WARN/WARN_ONCE/]
[akpm@linux-foundation.org: coding-style fixup]
[randy.dunlap@oracle.com: fix kernel/sysctl.c warning]
Signed-off-by: Dan Rosenberg <drosenberg@vsecurity.com>
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Cc: James Morris <jmorris@namei.org>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Thomas Graf <tgraf@infradead.org>
Cc: Eugene Teo <eugeneteo@kernel.org>
Cc: Kees Cook <kees.cook@canonical.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: David S. Miller <davem@davemloft.net>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Eric Paris <eparis@parisplace.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-01-12 16:59:41 -08:00
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2013-11-12 15:08:51 -08:00
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kptr_restrict for hiding kernel pointers from unprivileged users
Add the %pK printk format specifier and the /proc/sys/kernel/kptr_restrict
sysctl.
The %pK format specifier is designed to hide exposed kernel pointers,
specifically via /proc interfaces. Exposing these pointers provides an
easy target for kernel write vulnerabilities, since they reveal the
locations of writable structures containing easily triggerable function
pointers. The behavior of %pK depends on the kptr_restrict sysctl.
If kptr_restrict is set to 0, no deviation from the standard %p behavior
occurs. If kptr_restrict is set to 1, the default, if the current user
(intended to be a reader via seq_printf(), etc.) does not have CAP_SYSLOG
(currently in the LSM tree), kernel pointers using %pK are printed as 0's.
If kptr_restrict is set to 2, kernel pointers using %pK are printed as
0's regardless of privileges. Replacing with 0's was chosen over the
default "(null)", which cannot be parsed by userland %p, which expects
"(nil)".
[akpm@linux-foundation.org: check for IRQ context when !kptr_restrict, save an indent level, s/WARN/WARN_ONCE/]
[akpm@linux-foundation.org: coding-style fixup]
[randy.dunlap@oracle.com: fix kernel/sysctl.c warning]
Signed-off-by: Dan Rosenberg <drosenberg@vsecurity.com>
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Cc: James Morris <jmorris@namei.org>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Thomas Graf <tgraf@infradead.org>
Cc: Eugene Teo <eugeneteo@kernel.org>
Cc: Kees Cook <kees.cook@canonical.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: David S. Miller <davem@davemloft.net>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Eric Paris <eparis@parisplace.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-01-12 16:59:41 -08:00
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2006-12-07 02:14:11 +01:00
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2011-07-23 10:39:29 -07:00
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2009-04-02 15:49:29 -07:00
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kexec: add sysctl to disable kexec_load
For general-purpose (i.e. distro) kernel builds it makes sense to build
with CONFIG_KEXEC to allow end users to choose what kind of things they
want to do with kexec. However, in the face of trying to lock down a
system with such a kernel, there needs to be a way to disable kexec_load
(much like module loading can be disabled). Without this, it is too easy
for the root user to modify kernel memory even when CONFIG_STRICT_DEVMEM
and modules_disabled are set. With this change, it is still possible to
load an image for use later, then disable kexec_load so the image (or lack
of image) can't be altered.
The intention is for using this in environments where "perfect"
enforcement is hard. Without a verified boot, along with verified
modules, and along with verified kexec, this is trying to give a system a
better chance to defend itself (or at least grow the window of
discoverability) against attack in the face of a privilege escalation.
In my mind, I consider several boot scenarios:
1) Verified boot of read-only verified root fs loading fd-based
verification of kexec images.
2) Secure boot of writable root fs loading signed kexec images.
3) Regular boot loading kexec (e.g. kcrash) image early and locking it.
4) Regular boot with no control of kexec image at all.
1 and 2 don't exist yet, but will soon once the verified kexec series has
landed. 4 is the state of things now. The gap between 2 and 4 is too
large, so this change creates scenario 3, a middle-ground above 4 when 2
and 1 are not possible for a system.
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-01-23 15:55:59 -08:00
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2009-04-02 15:49:29 -07:00
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2013-01-04 15:34:50 -08:00
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2011-07-23 10:39:29 -07:00
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2013-10-07 11:28:40 +01:00
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2013-10-07 11:29:37 +01:00
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2014-01-27 17:03:40 -05:00
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2013-10-07 11:28:40 +01:00
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2013-10-07 11:29:37 +01:00
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2013-10-07 11:28:40 +01:00
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2013-10-07 11:28:55 +01:00
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2013-10-07 11:28:40 +01:00
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2013-10-07 11:28:55 +01:00
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2013-10-07 11:28:40 +01:00
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2005-04-16 15:20:36 -07:00
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2011-07-23 10:39:29 -07:00
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2005-04-16 15:20:36 -07:00
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2011-07-23 10:39:29 -07:00
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2005-04-16 15:20:36 -07:00
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2007-05-09 07:35:06 +02:00
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2006-08-05 12:14:32 -07:00
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2005-04-16 15:20:36 -07:00
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2011-11-29 15:08:36 +09:00
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2013-06-21 08:51:36 -07:00
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2011-11-29 15:08:36 +09:00
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2005-04-16 15:20:36 -07:00
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2007-05-09 07:14:03 +02:00
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2005-04-16 15:20:36 -07:00
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2012-01-12 17:20:27 -08:00
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2005-04-16 15:20:36 -07:00
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2011-02-06 21:00:41 +01:00
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2005-04-16 15:20:36 -07:00
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2011-07-23 10:39:29 -07:00
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2005-04-16 15:20:36 -07:00
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2011-07-23 10:39:29 -07:00
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2008-02-09 23:24:08 +01:00
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2009-07-03 14:20:17 +02:00
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2008-02-09 23:24:08 +01:00
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2009-07-03 14:20:17 +02:00
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2008-02-09 23:24:08 +01:00
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2009-07-03 14:20:17 +02:00
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2008-02-09 23:24:08 +01:00
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2009-07-03 14:20:17 +02:00
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2008-02-09 23:24:08 +01:00
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2009-07-03 14:20:17 +02:00
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2008-02-09 23:24:08 +01:00
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2005-04-16 15:20:36 -07:00
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2013-01-04 15:35:05 -08:00
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2011-07-23 10:39:29 -07:00
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2005-04-16 15:20:36 -07:00
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2011-07-23 10:39:29 -07:00
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2005-04-16 15:20:36 -07:00
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2011-07-26 16:08:48 -07:00
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sysctl: allow for strict write position handling
When writing to a sysctl string, each write, regardless of VFS position,
begins writing the string from the start. This means the contents of
the last write to the sysctl controls the string contents instead of the
first:
open("/proc/sys/kernel/modprobe", O_WRONLY) = 1
write(1, "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"..., 4096) = 4096
write(1, "/bin/true", 9) = 9
close(1) = 0
$ cat /proc/sys/kernel/modprobe
/bin/true
Expected behaviour would be to have the sysctl be "AAAA..." capped at
maxlen (in this case KMOD_PATH_LEN: 256), instead of truncating to the
contents of the second write. Similarly, multiple short writes would
not append to the sysctl.
The old behavior is unlike regular POSIX files enough that doing audits
of software that interact with sysctls can end up in unexpected or
dangerous situations. For example, "as long as the input starts with a
trusted path" turns out to be an insufficient filter, as what must also
happen is for the input to be entirely contained in a single write
syscall -- not a common consideration, especially for high level tools.
This provides kernel.sysctl_writes_strict as a way to make this behavior
act in a less surprising manner for strings, and disallows non-zero file
position when writing numeric sysctls (similar to what is already done
when reading from non-zero file positions). For now, the default (0) is
to warn about non-zero file position use, but retain the legacy
behavior. Setting this to -1 disables the warning, and setting this to
1 enables the file position respecting behavior.
[akpm@linux-foundation.org: fix build]
[akpm@linux-foundation.org: move misplaced hunk, per Randy]
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-06-06 14:37:19 -07:00
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2014-06-23 13:22:05 -07:00
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2011-07-23 10:39:29 -07:00
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2005-04-16 15:20:36 -07:00
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2008-10-17 15:01:07 -07:00
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2012-02-06 09:49:50 -08:00
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Fix: module signature vs tracepoints: add new TAINT_UNSIGNED_MODULE
Users have reported being unable to trace non-signed modules loaded
within a kernel supporting module signature.
This is caused by tracepoint.c:tracepoint_module_coming() refusing to
take into account tracepoints sitting within force-loaded modules
(TAINT_FORCED_MODULE). The reason for this check, in the first place, is
that a force-loaded module may have a struct module incompatible with
the layout expected by the kernel, and can thus cause a kernel crash
upon forced load of that module on a kernel with CONFIG_TRACEPOINTS=y.
Tracepoints, however, specifically accept TAINT_OOT_MODULE and
TAINT_CRAP, since those modules do not lead to the "very likely system
crash" issue cited above for force-loaded modules.
With kernels having CONFIG_MODULE_SIG=y (signed modules), a non-signed
module is tainted re-using the TAINT_FORCED_MODULE taint flag.
Unfortunately, this means that Tracepoints treat that module as a
force-loaded module, and thus silently refuse to consider any tracepoint
within this module.
Since an unsigned module does not fit within the "very likely system
crash" category of tainting, add a new TAINT_UNSIGNED_MODULE taint flag
to specifically address this taint behavior, and accept those modules
within Tracepoints. We use the letter 'X' as a taint flag character for
a module being loaded that doesn't know how to sign its name (proposed
by Steven Rostedt).
Also add the missing 'O' entry to trace event show_module_flags() list
for the sake of completeness.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
NAKed-by: Ingo Molnar <mingo@redhat.com>
CC: Thomas Gleixner <tglx@linutronix.de>
CC: David Howells <dhowells@redhat.com>
CC: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2014-03-13 12:11:30 +10:30
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2014-08-08 14:22:31 -07:00
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2005-04-16 15:20:36 -07:00
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2009-04-02 16:57:20 -07:00
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2011-07-23 10:39:29 -07:00
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2009-04-02 16:57:20 -07:00
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2011-07-23 10:39:29 -07:00
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2013-05-17 10:31:20 +08:00
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