commit b18cb64ead upstream.
This reverts more of:
b76437579d ("procfs: mark thread stack correctly in proc/<pid>/maps")
... which was partially reverted by:
65376df582 ("proc: revert /proc/<pid>/maps [stack:TID] annotation")
Originally, /proc/PID/task/TID/maps was the same as /proc/TID/maps.
In current kernels, /proc/PID/maps (or /proc/TID/maps even for
threads) shows "[stack]" for VMAs in the mm's stack address range.
In contrast, /proc/PID/task/TID/maps uses KSTK_ESP to guess the
target thread's stack's VMA. This is racy, probably returns garbage
and, on arches with CONFIG_TASK_INFO_IN_THREAD=y, is also crash-prone:
KSTK_ESP is not safe to use on tasks that aren't known to be running
ordinary process-context kernel code.
This patch removes the difference and just shows "[stack]" for VMAs
in the mm's stack range. This is IMO much more sensible -- the
actual "stack" address really is treated specially by the VM code,
and the current thread stack isn't even well-defined for programs
that frequently switch stacks on their own.
Reported-by: Jann Horn <jann@thejh.net>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Linux API <linux-api@vger.kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tycho Andersen <tycho.andersen@canonical.com>
Link: http://lkml.kernel.org/r/3e678474ec14e0a0ec34c611016753eea2e1b8ba.1475257877.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
[bwh: Backported to 3.16: Squash in the earlier commits 58cb65487e
"proc/maps: make vm_is_stack() logic namespace-friendly" and
65376df582 "proc: revert /proc/<pid>/maps [stack:TID] annotation",
which would introduce build failures if applied separately.]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
commit ab6ecf247a upstream.
In commit ab676b7d6f ("pagemap: do not leak physical addresses to
non-privileged userspace"), the /proc/PID/pagemap is restricted to be
readable only by CAP_SYS_ADMIN to address some security issue.
In commit 1c90308e7a ("pagemap: hide physical addresses from
non-privileged users"), the restriction is relieved to make
/proc/PID/pagemap readable, but hide the physical addresses for
non-privileged users.
But the swap entries are readable for non-privileged users too. This
has some security issues. For example, for page under migrating, the
swap entry has physical address information. So, in this patch, the
swap entries are hided for non-privileged users too.
Link: http://lkml.kernel.org/r/20180508012745.7238-1-ying.huang@intel.com
Fixes: 1c90308e7a ("pagemap: hide physical addresses from non-privileged users")
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Suggested-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Reviewed-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: Andrei Vagin <avagin@openvz.org>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Daniel Colascione <dancol@google.com>
Cc: Zi Yan <zi.yan@cs.rutgers.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[bwh: Backported to 3.16:
- Only PTEs can be swap entries
- Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
commit 1c90308e7a upstream.
This patch makes pagemap readable for normal users and hides physical
addresses from them. For some use-cases PFN isn't required at all.
See http://lkml.kernel.org/r/1425935472-17949-1-git-send-email-kirill@shutemov.name
Fixes: ab676b7d6f ("pagemap: do not leak physical addresses to non-privileged userspace")
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Reviewed-by: Mark Williamson <mwilliamson@undo-software.com>
Tested-by: Mark Williamson <mwilliamson@undo-software.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[bwh: Backported to 3.16:
- Add the same check in the places where we look up a PFN
- Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
commit a0b0d1c345 upstream.
proc_sys_link_fill_cache() does not take currently unregistering sysctl
tables into account, which might result into a page fault in
sysctl_follow_link() - add a check to fix it.
This bug has been present since v3.4.
Link: http://lkml.kernel.org/r/20180228013506.4915-1-danilokrummrich@dk-develop.de
Fixes: 0e47c99d7f ("sysctl: Replace root_list with links between sysctl_table_sets")
Signed-off-by: Danilo Krummrich <danilokrummrich@dk-develop.de>
Acked-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: "Luis R . Rodriguez" <mcgrof@kernel.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
commit 1da4b35b00 upstream.
We have to handle non-linear mappings for /proc/PID/{smaps,clear_refs}
which is unused now. Let's drop it.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[bwh: Backported to 3.16:
- Deleted code is slightly different
- Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
commit e96f46ee85 upstream.
The style for the 'status' file is CamelCase or this. _.
Fixes: fae1fa0fc ("proc: Provide details on speculation flaw mitigations")
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
commit 356e4bfff2 upstream.
For certain use cases it is desired to enforce mitigations so they cannot
be undone afterwards. That's important for loader stubs which want to
prevent a child from disabling the mitigation again. Will also be used for
seccomp(). The extra state preserving of the prctl state for SSB is a
preparatory step for EBPF dymanic speculation control.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
[bwh: Backported to 3.16: adjust filename, context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
commit fae1fa0fc6 upstream.
As done with seccomp and no_new_privs, also show speculation flaw
mitigation state in /proc/$pid/status.
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
commit 89c5b53b16 upstream.
Patch series "sysctl: few fixes", v5.
I've been working on making kmod more deterministic, and as I did that I
couldn't help but notice a few issues with sysctl. My end goal was just
to fix unsigned int support, which back then was completely broken.
Liping Zhang has sent up small atomic fixes, however it still missed yet
one more fix and Alexey Dobriyan had also suggested to just drop array
support given its complexity.
I have inspected array support using Coccinelle and indeed its not that
popular, so if in fact we can avoid it for new interfaces, I agree its
best.
I did develop a sysctl stress driver but will hold that off for another
series.
This patch (of 5):
Commit 7c60c48f58 ("sysctl: Improve the sysctl sanity checks")
improved sanity checks considerbly, however the enhancements on
sysctl_check_table() meant adding a functional change so that only the
last table entry's sanity error is propagated. It also changed the way
errors were propagated so that each new check reset the err value, this
means only last sanity check computed is used for an error. This has
been in the kernel since v3.4 days.
Fix this by carrying on errors from previous checks and iterations as we
traverse the table and ensuring we keep any error from previous checks.
We keep iterating on the table even if an error is found so we can
complain for all errors found in one shot. This works as -EINVAL is
always returned on error anyway, and the check for error is any non-zero
value.
Fixes: 7c60c48f58 ("sysctl: Improve the sysctl sanity checks")
Link: http://lkml.kernel.org/r/20170519033554.18592-2-mcgrof@kernel.org
Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
commit caaee6234d upstream.
By checking the effective credentials instead of the real UID / permitted
capabilities, ensure that the calling process actually intended to use its
credentials.
To ensure that all ptrace checks use the correct caller credentials (e.g.
in case out-of-tree code or newly added code omits the PTRACE_MODE_*CREDS
flag), use two new flags and require one of them to be set.
The problem was that when a privileged task had temporarily dropped its
privileges, e.g. by calling setreuid(0, user_uid), with the intent to
perform following syscalls with the credentials of a user, it still passed
ptrace access checks that the user would not be able to pass.
While an attacker should not be able to convince the privileged task to
perform a ptrace() syscall, this is a problem because the ptrace access
check is reused for things in procfs.
In particular, the following somewhat interesting procfs entries only rely
on ptrace access checks:
/proc/$pid/stat - uses the check for determining whether pointers
should be visible, useful for bypassing ASLR
/proc/$pid/maps - also useful for bypassing ASLR
/proc/$pid/cwd - useful for gaining access to restricted
directories that contain files with lax permissions, e.g. in
this scenario:
lrwxrwxrwx root root /proc/13020/cwd -> /root/foobar
drwx------ root root /root
drwxr-xr-x root root /root/foobar
-rw-r--r-- root root /root/foobar/secret
Therefore, on a system where a root-owned mode 6755 binary changes its
effective credentials as described and then dumps a user-specified file,
this could be used by an attacker to reveal the memory layout of root's
processes or reveal the contents of files he is not allowed to access
(through /proc/$pid/cwd).
[akpm@linux-foundation.org: fix warning]
Signed-off-by: Jann Horn <jann@thejh.net>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Casey Schaufler <casey@schaufler-ca.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Morris <james.l.morris@oracle.com>
Cc: "Serge E. Hallyn" <serge.hallyn@ubuntu.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Willy Tarreau <w@1wt.eu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[bwh: Backported to 3.16:
- Update mm_access() calls in fs/proc/task_{,no}mmu.c too
- Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
commit 1be7107fbe upstream.
Stack guard page is a useful feature to reduce a risk of stack smashing
into a different mapping. We have been using a single page gap which
is sufficient to prevent having stack adjacent to a different mapping.
But this seems to be insufficient in the light of the stack usage in
userspace. E.g. glibc uses as large as 64kB alloca() in many commonly
used functions. Others use constructs liks gid_t buffer[NGROUPS_MAX]
which is 256kB or stack strings with MAX_ARG_STRLEN.
This will become especially dangerous for suid binaries and the default
no limit for the stack size limit because those applications can be
tricked to consume a large portion of the stack and a single glibc call
could jump over the guard page. These attacks are not theoretical,
unfortunatelly.
Make those attacks less probable by increasing the stack guard gap
to 1MB (on systems with 4k pages; but make it depend on the page size
because systems with larger base pages might cap stack allocations in
the PAGE_SIZE units) which should cover larger alloca() and VLA stack
allocations. It is obviously not a full fix because the problem is
somehow inherent, but it should reduce attack space a lot.
One could argue that the gap size should be configurable from userspace,
but that can be done later when somebody finds that the new 1MB is wrong
for some special case applications. For now, add a kernel command line
option (stack_guard_gap) to specify the stack gap size (in page units).
Implementation wise, first delete all the old code for stack guard page:
because although we could get away with accounting one extra page in a
stack vma, accounting a larger gap can break userspace - case in point,
a program run with "ulimit -S -v 20000" failed when the 1MB gap was
counted for RLIMIT_AS; similar problems could come with RLIMIT_MLOCK
and strict non-overcommit mode.
Instead of keeping gap inside the stack vma, maintain the stack guard
gap as a gap between vmas: using vm_start_gap() in place of vm_start
(or vm_end_gap() in place of vm_end if VM_GROWSUP) in just those few
places which need to respect the gap - mainly arch_get_unmapped_area(),
and and the vma tree's subtree_gap support for that.
Original-patch-by: Oleg Nesterov <oleg@redhat.com>
Original-patch-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Tested-by: Helge Deller <deller@gmx.de> # parisc
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[Hugh Dickins: Backported to 3.16]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
commit 22f6b4d34f upstream.
Today proc and sysfs do not contain any executable files. Several
applications today mount proc or sysfs without noexec and nosuid and
then depend on there being no exectuables files on proc or sysfs.
Having any executable files show on proc or sysfs would cause
a user space visible regression, and most likely security problems.
Therefore commit to never allowing executables on proc and sysfs by
adding a new flag to mark them as filesystems without executables and
enforce that flag.
Test the flag where MNT_NOEXEC is tested today, so that the only user
visible effect will be that exectuables will be treated as if the
execute bit is cleared.
The filesystems proc and sysfs do not currently incoporate any
executable files so this does not result in any user visible effects.
This makes it unnecessary to vet changes to proc and sysfs tightly for
adding exectuable files or changes to chattr that would modify
existing files, as no matter what the individual file say they will
not be treated as exectuable files by the vfs.
Not having to vet changes to closely is important as without this we
are only one proc_create call (or another goof up in the
implementation of notify_change) from having problematic executables
on proc. Those mistakes are all too easy to make and would create
a situation where there are security issues or the assumptions of
some program having to be broken (and cause userspace regressions).
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
[bwh: Backported to 3.16: we don't have super_block::s_iflags; use
file_system_type::fs_flags instead]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
commit 31051c85b5 upstream.
inode_change_ok() will be resposible for clearing capabilities and IMA
extended attributes and as such will need dentry. Give it as an argument
to inode_change_ok() instead of an inode. Also rename inode_change_ok()
to setattr_prepare() to better relect that it does also some
modifications in addition to checks.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>
[bwh: Backported to 3.16:
- Drop changes to orangefs, overlayfs
- Adjust filenames, context
- In nfsd, pass dentry to nfsd_sanitize_attrs()
- Update ext3 as well]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
This reverts commit be9df69943, which was
commit 31051c85b5 upstream. The backport
breaks fuse and makes a mess of xfs, which can be improved by picking
further upstream commits as I should have done in the first place.
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
commit 31051c85b5 upstream.
inode_change_ok() will be resposible for clearing capabilities and IMA
extended attributes and as such will need dentry. Give it as an argument
to inode_change_ok() instead of an inode. Also rename inode_change_ok()
to setattr_prepare() to better relect that it does also some
modifications in addition to checks.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>
[bwh: Backported to 3.16:
- Drop changes to orangefs, overlayfs
- Adjust filenames, context
- In fuse, pass dentry to fuse_do_setattr()
- In nfsd, pass dentry to nfsd_sanitize_attrs()
- In xfs, pass dentry to xfs_setattr_nonsize() and xfs_setattr_size()
- Update ext3 as well]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
commit e54ad7f1ee upstream.
This prevents stacking filesystems (ecryptfs and overlayfs) from using
procfs as lower filesystem. There is too much magic going on inside
procfs, and there is no good reason to stack stuff on top of procfs.
(For example, procfs does access checks in VFS open handlers, and
ecryptfs by design calls open handlers from a kernel thread that doesn't
drop privileges or so.)
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
commit 8148a73c99 upstream.
If /proc/<PID>/environ gets read before the envp[] array is fully set up
in create_{aout,elf,elf_fdpic,flat}_tables(), we might end up trying to
read more bytes than are actually written, as env_start will already be
set but env_end will still be zero, making the range calculation
underflow, allowing to read beyond the end of what has been written.
Fix this as it is done for /proc/<PID>/cmdline by testing env_end for
zero. It is, apparently, intentionally set last in create_*_tables().
This bug was found by the PaX size_overflow plugin that detected the
arithmetic underflow of 'this_len = env_end - (env_start + src)' when
env_end is still zero.
The expected consequence is that userland trying to access
/proc/<PID>/environ of a not yet fully set up process may get
inconsistent data as we're in the middle of copying in the environment
variables.
Fixes: https://forums.grsecurity.net/viewtopic.php?f=3&t=4363
Fixes: https://bugzilla.kernel.org/show_bug.cgi?id=116461
Signed-off-by: Mathias Krause <minipli@googlemail.com>
Cc: Emese Revfy <re.emese@gmail.com>
Cc: Pax Team <pageexec@freemail.hu>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Mateusz Guzik <mguzik@redhat.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Jarod Wilson <jarod@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
commit b2f73922d1 upstream.
So the /proc/PID/stat 'wchan' field (the 30th field, which contains
the absolute kernel address of the kernel function a task is blocked in)
leaks absolute kernel addresses to unprivileged user-space:
seq_put_decimal_ull(m, ' ', wchan);
The absolute address might also leak via /proc/PID/wchan as well, if
KALLSYMS is turned off or if the symbol lookup fails for some reason:
static int proc_pid_wchan(struct seq_file *m, struct pid_namespace *ns,
struct pid *pid, struct task_struct *task)
{
unsigned long wchan;
char symname[KSYM_NAME_LEN];
wchan = get_wchan(task);
if (lookup_symbol_name(wchan, symname) < 0) {
if (!ptrace_may_access(task, PTRACE_MODE_READ))
return 0;
seq_printf(m, "%lu", wchan);
} else {
seq_printf(m, "%s", symname);
}
return 0;
}
This isn't ideal, because for example it trivially leaks the KASLR offset
to any local attacker:
fomalhaut:~> printf "%016lx\n" $(cat /proc/$$/stat | cut -d' ' -f35)
ffffffff8123b380
Most real-life uses of wchan are symbolic:
ps -eo pid:10,tid:10,wchan:30,comm
and procps uses /proc/PID/wchan, not the absolute address in /proc/PID/stat:
triton:~/tip> strace -f ps -eo pid:10,tid:10,wchan:30,comm 2>&1 | grep wchan | tail -1
open("/proc/30833/wchan", O_RDONLY) = 6
There's one compatibility quirk here: procps relies on whether the
absolute value is non-zero - and we can provide that functionality
by outputing "0" or "1" depending on whether the task is blocked
(whether there's a wchan address).
These days there appears to be very little legitimate reason
user-space would be interested in the absolute address. The
absolute address is mostly historic: from the days when we
didn't have kallsyms and user-space procps had to do the
decoding itself via the System.map.
So this patch sets all numeric output to "0" or "1" and keeps only
symbolic output, in /proc/PID/wchan.
( The absolute sleep address can generally still be profiled via
perf, by tasks with sufficient privileges. )
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Kostya Serebryany <kcc@google.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: kasan-dev <kasan-dev@googlegroups.com>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/20150930135917.GA3285@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
[ kamal: backport to 3.16-stable: proc_pid_wchan context ]
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
commit 54708d2858 upstream.
The commit 96d0df79f2 ("proc: make proc_fd_permission() thread-friendly")
fixed the access to /proc/self/fd from sub-threads, but introduced another
problem: a sub-thread can't access /proc/<tid>/fd/ or /proc/thread-self/fd
if generic_permission() fails.
Change proc_fd_permission() to check same_thread_group(pid_task(), current).
Fixes: 96d0df79f2 ("proc: make proc_fd_permission() thread-friendly")
Reported-by: "Jin, Yihua" <yihua.jin@intel.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
commit eb6d38d542 upstream.
Add a new function proc_create_mount_point that when used to creates a
directory that can not be added to.
Add a new function is_empty_pde to test if a function is a mount
point.
Update the code to use make_empty_dir_inode when reporting
a permanently empty directory to the vfs.
Update the code to not allow adding to permanently empty directories.
Update /proc/openprom and /proc/fs/nfsd to be permanently empty directories.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
[ luis: backported to 3.16: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
commit f9bd6733d3 upstream.
Add a magic sysctl table sysctl_mount_point that when used to
create a directory forces that directory to be permanently empty.
Update the code to use make_empty_dir_inode when accessing permanently
empty directories.
Update the code to not allow adding to permanently empty directories.
Update /proc/sys/fs/binfmt_misc to be a permanently empty directory.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
commit 1b852bceb0 upstream.
Fresh mounts of proc and sysfs are a very special case that works very
much like a bind mount. Unfortunately the current structure can not
preserve the MNT_LOCK... mount flags. Therefore refactor the logic
into a form that can be modified to preserve those lock bits.
Add a new filesystem flag FS_USERNS_VISIBLE that requires some mount
of the filesystem be fully visible in the current mount namespace,
before the filesystem may be mounted.
Move the logic for calling fs_fully_visible from proc and sysfs into
fs/namespace.c where it has greater access to mount namespace state.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
commit ab676b7d6f upstream.
As pointed by recent post[1] on exploiting DRAM physical imperfection,
/proc/PID/pagemap exposes sensitive information which can be used to do
attacks.
This disallows anybody without CAP_SYS_ADMIN to read the pagemap.
[1] http://googleprojectzero.blogspot.com/2015/03/exploiting-dram-rowhammer-bug-to-gain.html
[ Eventually we might want to do anything more finegrained, but for now
this is the simple model. - Linus ]
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Acked-by: Andy Lutomirski <luto@amacapital.net>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Mark Seaborn <mseaborn@chromium.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
commit 05fbf357d9 upstream.
Lockless access to pte in pagemap_pte_range() might race with page
migration and trigger BUG_ON(!PageLocked()) in migration_entry_to_page():
CPU A (pagemap) CPU B (migration)
lock_page()
try_to_unmap(page, TTU_MIGRATION...)
make_migration_entry()
set_pte_at()
<read *pte>
pte_to_pagemap_entry()
remove_migration_ptes()
unlock_page()
if(is_migration_entry())
migration_entry_to_page()
BUG_ON(!PageLocked(page))
Also lockless read might be non-atomic if pte is larger than wordsize.
Other pte walkers (smaps, numa_maps, clear_refs) already lock ptes.
Fixes: 052fb0d635 ("proc: report file/anon bit in /proc/pid/pagemap")
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Reported-by: Andrey Ryabinin <a.ryabinin@samsung.com>
Reviewed-by: Cyrill Gorcunov <gorcunov@openvz.org>
Acked-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
commit 81d0fa623c upstream.
If a /proc/pid/pagemap read spans a [VMA, an unmapped region, then a
VM_SOFTDIRTY VMA], the virtual pages in the unmapped region are reported
as softdirty. Here's a program to demonstrate the bug:
int main() {
const uint64_t PAGEMAP_SOFTDIRTY = 1ul << 55;
uint64_t pme[3];
int fd = open("/proc/self/pagemap", O_RDONLY);;
char *m = mmap(NULL, 3 * getpagesize(), PROT_READ,
MAP_ANONYMOUS | MAP_SHARED, -1, 0);
munmap(m + getpagesize(), getpagesize());
pread(fd, pme, 24, (unsigned long) m / getpagesize() * 8);
assert(pme[0] & PAGEMAP_SOFTDIRTY); /* passes */
assert(!(pme[1] & PAGEMAP_SOFTDIRTY)); /* fails */
assert(pme[2] & PAGEMAP_SOFTDIRTY); /* passes */
return 0;
}
(Note that all pages in new VMAs are softdirty until cleared).
Tested:
Used the program given above. I'm going to include this code in
a selftest in the future.
[n-horiguchi@ah.jp.nec.com: prevent pagemap_pte_range() from overrunning]
Signed-off-by: Peter Feiner <pfeiner@google.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Jamie Liu <jamieliu@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[ luis: 3.16-stable prereq for:
05fbf357d9 "proc/pagemap: walk page tables under pte lock" ]
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
commit 7e0e953bb0 upstream.
use_pde()/unuse_pde() in ->follow_link()/->put_link() resp.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
commit c291ee6221 upstream.
Since the rework of the sparse interrupt code to actually free the
unused interrupt descriptors there exists a race between the /proc
interfaces to the irq subsystem and the code which frees the interrupt
descriptor.
CPU0 CPU1
show_interrupts()
desc = irq_to_desc(X);
free_desc(desc)
remove_from_radix_tree();
kfree(desc);
raw_spinlock_irq(&desc->lock);
/proc/interrupts is the only interface which can actively corrupt
kernel memory via the lock access. /proc/stat can only read from freed
memory. Extremly hard to trigger, but possible.
The interfaces in /proc/irq/N/ are not affected by this because the
removal of the proc file is serialized in procfs against concurrent
readers/writers. The removal happens before the descriptor is freed.
For architectures which have CONFIG_SPARSE_IRQ=n this is a non issue
as the descriptor is never freed. It's merely cleared out with the irq
descriptor lock held. So any concurrent proc access will either see
the old correct value or the cleared out ones.
Protect the lookup and access to the irq descriptor in
show_interrupts() with the sparse_irq_lock.
Provide kstat_irqs_usr() which is protecting the lookup and access
with sparse_irq_lock and switch /proc/stat to use it.
Document the existing kstat_irqs interfaces so it's clear that the
caller needs to take care about protection. The users of these
interfaces are either not affected due to SPARSE_IRQ=n or already
protected against removal.
Fixes: 1f5a5b87f7 "genirq: Implement a sane sparse_irq allocator"
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
commit 9cc46516dd upstream.
- Expose the knob to user space through a proc file /proc/<pid>/setgroups
A value of "deny" means the setgroups system call is disabled in the
current processes user namespace and can not be enabled in the
future in this user namespace.
A value of "allow" means the segtoups system call is enabled.
- Descendant user namespaces inherit the value of setgroups from
their parents.
- A proc file is used (instead of a sysctl) as sysctls currently do
not allow checking the permissions at open time.
- Writing to the proc file is restricted to before the gid_map
for the user namespace is set.
This ensures that disabling setgroups at a user namespace
level will never remove the ability to call setgroups
from a process that already has that ability.
A process may opt in to the setgroups disable for itself by
creating, entering and configuring a user namespace or by calling
setns on an existing user namespace with setgroups disabled.
Processes without privileges already can not call setgroups so this
is a noop. Prodcess with privilege become processes without
privilege when entering a user namespace and as with any other path
to dropping privilege they would not have the ability to call
setgroups. So this remains within the bounds of what is possible
without a knob to disable setgroups permanently in a user namespace.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
commit 7d8b6c6375 upstream.
This is effectively a revert of 7b9a7ec565
plus fixing it a different way...
We found, when trying to run an application from an application which
had dropped privs that the kernel does security checks on undefined
capability bits. This was ESPECIALLY difficult to debug as those
undefined bits are hidden from /proc/$PID/status.
Consider a root application which drops all capabilities from ALL 4
capability sets. We assume, since the application is going to set
eff/perm/inh from an array that it will clear not only the defined caps
less than CAP_LAST_CAP, but also the higher 28ish bits which are
undefined future capabilities.
The BSET gets cleared differently. Instead it is cleared one bit at a
time. The problem here is that in security/commoncap.c::cap_task_prctl()
we actually check the validity of a capability being read. So any task
which attempts to 'read all things set in bset' followed by 'unset all
things set in bset' will not even attempt to unset the undefined bits
higher than CAP_LAST_CAP.
So the 'parent' will look something like:
CapInh: 0000000000000000
CapPrm: 0000000000000000
CapEff: 0000000000000000
CapBnd: ffffffc000000000
All of this 'should' be fine. Given that these are undefined bits that
aren't supposed to have anything to do with permissions. But they do...
So lets now consider a task which cleared the eff/perm/inh completely
and cleared all of the valid caps in the bset (but not the invalid caps
it couldn't read out of the kernel). We know that this is exactly what
the libcap-ng library does and what the go capabilities library does.
They both leave you in that above situation if you try to clear all of
you capapabilities from all 4 sets. If that root task calls execve()
the child task will pick up all caps not blocked by the bset. The bset
however does not block bits higher than CAP_LAST_CAP. So now the child
task has bits in eff which are not in the parent. These are
'meaningless' undefined bits, but still bits which the parent doesn't
have.
The problem is now in cred_cap_issubset() (or any operation which does a
subset test) as the child, while a subset for valid cap bits, is not a
subset for invalid cap bits! So now we set durring commit creds that
the child is not dumpable. Given it is 'more priv' than its parent. It
also means the parent cannot ptrace the child and other stupidity.
The solution here:
1) stop hiding capability bits in status
This makes debugging easier!
2) stop giving any task undefined capability bits. it's simple, it you
don't put those invalid bits in CAP_FULL_SET you won't get them in init
and you won't get them in any other task either.
This fixes the cap_issubset() tests and resulting fallout (which
made the init task in a docker container untraceable among other
things)
3) mask out undefined bits when sys_capset() is called as it might use
~0, ~0 to denote 'all capabilities' for backward/forward compatibility.
This lets 'capsh --caps="all=eip" -- -c /bin/bash' run.
4) mask out undefined bit when we read a file capability off of disk as
again likely all bits are set in the xattr for forward/backward
compatibility.
This lets 'setcap all+pe /bin/bash; /bin/bash' run
Signed-off-by: Eric Paris <eparis@redhat.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: Andrew Vagin <avagin@openvz.org>
Cc: Andrew G. Morgan <morgan@kernel.org>
Cc: Serge E. Hallyn <serge.hallyn@canonical.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Steve Grubb <sgrubb@redhat.com>
Cc: Dan Walsh <dwalsh@redhat.com>
Signed-off-by: James Morris <james.l.morris@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
These two patches are supposed to "fix" failed order-4 memory
allocations which have been observed when reading /proc/stat. The
problem has been observed on s390 as well as on x86.
To address the problem change the seq_file memory allocations to
fallback to use vmalloc, so that allocations also work if memory is
fragmented.
This approach seems to be simpler and less intrusive than changing
/proc/stat to use an interator. Also it "fixes" other users as well,
which use seq_file's single_open() interface.
This patch (of 2):
Use seq_file's single_open_size() to preallocate a buffer that is large
enough to hold the whole output, instead of open coding it. Also
calculate the requested size using the number of online cpus instead of
possible cpus, since the size of the output only depends on the number
of online cpus.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Ian Kent <raven@themaw.net>
Cc: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Cc: Thorsten Diehl <thorsten.diehl@de.ibm.com>
Cc: Andrea Righi <andrea@betterlinux.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Stefan Bader <stefan.bader@canonical.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Now that 3.15 is released, this merges the 'next' branch into 'master',
bringing us to the normal situation where my 'master' branch is the
merge window.
* accumulated work in next: (6809 commits)
ufs: sb mutex merge + mutex_destroy
powerpc: update comments for generic idle conversion
cris: update comments for generic idle conversion
idle: remove cpu_idle() forward declarations
nbd: zero from and len fields in NBD_CMD_DISCONNECT.
mm: convert some level-less printks to pr_*
MAINTAINERS: adi-buildroot-devel is moderated
MAINTAINERS: add linux-api for review of API/ABI changes
mm/kmemleak-test.c: use pr_fmt for logging
fs/dlm/debug_fs.c: replace seq_printf by seq_puts
fs/dlm/lockspace.c: convert simple_str to kstr
fs/dlm/config.c: convert simple_str to kstr
mm: mark remap_file_pages() syscall as deprecated
mm: memcontrol: remove unnecessary memcg argument from soft limit functions
mm: memcontrol: clean up memcg zoneinfo lookup
mm/memblock.c: call kmemleak directly from memblock_(alloc|free)
mm/mempool.c: update the kmemleak stack trace for mempool allocations
lib/radix-tree.c: update the kmemleak stack trace for radix tree allocations
mm: introduce kmemleak_update_trace()
mm/kmemleak.c: use %u to print ->checksum
...
The age table walker doesn't check non-present hugetlb entry in common
path, so hugetlb_entry() callbacks must check it. The reason for this
behavior is that some callers want to handle it in its own way.
[ I think that reason is bogus, btw - it should just do what the regular
code does, which is to call the "pte_hole()" function for such hugetlb
entries - Linus]
However, some callers don't check it now, which causes unpredictable
result, for example when we have a race between migrating hugepage and
reading /proc/pid/numa_maps. This patch fixes it by adding !pte_present
checks on buggy callbacks.
This bug exists for years and got visible by introducing hugepage
migration.
ChangeLog v2:
- fix if condition (check !pte_present() instead of pte_present())
Reported-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: <stable@vger.kernel.org> [3.12+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
[ Backported to 3.15. Signed-off-by: Josh Boyer <jwboyer@fedoraproject.org> ]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull x86 cdso updates from Peter Anvin:
"Vdso cleanups and improvements largely from Andy Lutomirski. This
makes the vdso a lot less ''special''"
* 'x86/vdso' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/vdso, build: Make LE access macros clearer, host-safe
x86/vdso, build: Fix cross-compilation from big-endian architectures
x86/vdso, build: When vdso2c fails, unlink the output
x86, vdso: Fix an OOPS accessing the HPET mapping w/o an HPET
x86, mm: Replace arch_vma_name with vm_ops->name for vsyscalls
x86, mm: Improve _install_special_mapping and fix x86 vdso naming
mm, fs: Add vm_ops->name as an alternative to arch_vma_name
x86, vdso: Fix an OOPS accessing the HPET mapping w/o an HPET
x86, vdso: Remove vestiges of VDSO_PRELINK and some outdated comments
x86, vdso: Move the vvar and hpet mappings next to the 64-bit vDSO
x86, vdso: Move the 32-bit vdso special pages after the text
x86, vdso: Reimplement vdso.so preparation in build-time C
x86, vdso: Move syscall and sysenter setup into kernel/cpu/common.c
x86, vdso: Clean up 32-bit vs 64-bit vdso params
x86, mm: Ensure correct alignment of the fixmap
clear_refs_write() is called earlier than clear_soft_dirty() and it is
more natural to clear VM_SOFTDIRTY (which belongs to VMA entry but not
PTEs) that early instead of clearing it a way deeper inside call chain.
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
arch_vma_name sucks. It's a silly hack, and it's annoying to
implement correctly. In fact, AFAICS, even the straightforward x86
implementation is incorrect (I suspect that it breaks if the vdso
mapping is split or gets remapped).
This adds a new vm_ops->name operation that can replace it. The
followup patches will remove all uses of arch_vma_name on x86,
fixing a couple of annoyances in the process.
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Link: http://lkml.kernel.org/r/2eee21791bb36a0a408c5c2bdb382a9e6a41ca4a.1400538962.git.luto@amacapital.net
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Pull vfs updates from Al Viro:
"The first vfs pile, with deep apologies for being very late in this
window.
Assorted cleanups and fixes, plus a large preparatory part of iov_iter
work. There's a lot more of that, but it'll probably go into the next
merge window - it *does* shape up nicely, removes a lot of
boilerplate, gets rid of locking inconsistencie between aio_write and
splice_write and I hope to get Kent's direct-io rewrite merged into
the same queue, but some of the stuff after this point is having
(mostly trivial) conflicts with the things already merged into
mainline and with some I want more testing.
This one passes LTP and xfstests without regressions, in addition to
usual beating. BTW, readahead02 in ltp syscalls testsuite has started
giving failures since "mm/readahead.c: fix readahead failure for
memoryless NUMA nodes and limit readahead pages" - might be a false
positive, might be a real regression..."
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (63 commits)
missing bits of "splice: fix racy pipe->buffers uses"
cifs: fix the race in cifs_writev()
ceph_sync_{,direct_}write: fix an oops on ceph_osdc_new_request() failure
kill generic_file_buffered_write()
ocfs2_file_aio_write(): switch to generic_perform_write()
ceph_aio_write(): switch to generic_perform_write()
xfs_file_buffered_aio_write(): switch to generic_perform_write()
export generic_perform_write(), start getting rid of generic_file_buffer_write()
generic_file_direct_write(): get rid of ppos argument
btrfs_file_aio_write(): get rid of ppos
kill the 5th argument of generic_file_buffered_write()
kill the 4th argument of __generic_file_aio_write()
lustre: don't open-code kernel_recvmsg()
ocfs2: don't open-code kernel_recvmsg()
drbd: don't open-code kernel_recvmsg()
constify blk_rq_map_user_iov() and friends
lustre: switch to kernel_sendmsg()
ocfs2: don't open-code kernel_sendmsg()
take iov_iter stuff to mm/iov_iter.c
process_vm_access: tidy up a bit
...
Pull audit updates from Eric Paris.
* git://git.infradead.org/users/eparis/audit: (28 commits)
AUDIT: make audit_is_compat depend on CONFIG_AUDIT_COMPAT_GENERIC
audit: renumber AUDIT_FEATURE_CHANGE into the 1300 range
audit: do not cast audit_rule_data pointers pointlesly
AUDIT: Allow login in non-init namespaces
audit: define audit_is_compat in kernel internal header
kernel: Use RCU_INIT_POINTER(x, NULL) in audit.c
sched: declare pid_alive as inline
audit: use uapi/linux/audit.h for AUDIT_ARCH declarations
syscall_get_arch: remove useless function arguments
audit: remove stray newline from audit_log_execve_info() audit_panic() call
audit: remove stray newlines from audit_log_lost messages
audit: include subject in login records
audit: remove superfluous new- prefix in AUDIT_LOGIN messages
audit: allow user processes to log from another PID namespace
audit: anchor all pid references in the initial pid namespace
audit: convert PPIDs to the inital PID namespace.
pid: get pid_t ppid of task in init_pid_ns
audit: rename the misleading audit_get_context() to audit_take_context()
audit: Add generic compat syscall support
audit: Add CONFIG_HAVE_ARCH_AUDITSYSCALL
...
/proc/self/make-it-fail is a boolean, but accepts any number, including
negative ones. Change variable to unsigned, and cap upper bound at 1.
[akpm@linux-foundation.org: don't make make_it_fail unsigned]
Signed-off-by: Dave Jones <davej@fedoraproject.org>
Reviewed-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently when an empty PT_NOTE is detected, vmcore initialization
fails. It sounds too harsh. Because PT_NOTE could be empty, for
example, one offlined a cpu but never restarted kdump service, and after
crash, PT_NOTE program header is there but no data contains. It's
better to warn about the empty PT_NOTE and continue to initialise
vmcore.
And ultimately the multiple PT_NOTE are merged into a single one, all
empty PT_NOTE are discarded naturally during the merge. So empty
PT_NOTE is not visible to user space and vmcore is as good as expected.
Signed-off-by: WANG Chao <chaowang@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com>
Cc: Greg Pearson <greg.pearson@hp.com>
Cc: Baoquan He <bhe@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
get_task_state() uses the most significant bit to report the state to
user-space, this means that EXIT_ZOMBIE->EXIT_TRACE->EXIT_DEAD transition
can be noticed via /proc as Z -> X -> Z change. Note that this was
possible even before EXIT_TRACE was introduced.
This is not really bad but imho it make sense to hide EXIT_TRACE from
user-space completely. So the patch simply swaps EXIT_ZOMBIE and
EXIT_DEAD, this way EXIT_TRACE will be seen as EXIT_ZOMBIE by user-space.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Jan Kratochvil <jan.kratochvil@redhat.com>
Cc: Michal Schmidt <mschmidt@redhat.com>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Lennart Poettering <lpoetter@redhat.com>
Cc: Roland McGrath <roland@hack.frob.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The /proc/*/pagemap contain sensitive information and currently its mode
is 0444. Change this to 0400, so the VFS will prevent unprivileged
processes from getting file descriptors on arbitrary privileged
/proc/*/pagemap files.
This reduces the scope of address space leaking and bypasses by protecting
already running processes.
Signed-off-by: Djalal Harouni <tixxdz@opendz.org>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Andy Lutomirski <luto@amacapital.net>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
These procfs files contain sensitive information and currently their
mode is 0444. Change this to 0400, so the VFS will be able to block
unprivileged processes from getting file descriptors on arbitrary
privileged /proc/*/{stack,syscall,personality} files.
This reduces the scope of ASLR leaking and bypasses by protecting already
running processes.
Signed-off-by: Djalal Harouni <tixxdz@opendz.org>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Andy Lutomirski <luto@amacapital.net>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Replace rcu_assign_pointer(x, NULL) with RCU_INIT_POINTER(x, NULL)
The rcu_assign_pointer() ensures that the initialization of a structure
is carried out before storing a pointer to that structure. And in the
case of the NULL pointer, there is no structure to initialize. So,
rcu_assign_pointer(p, NULL) can be safely converted to
RCU_INIT_POINTER(p, NULL)
Signed-off-by: Monam Agarwal <monamagarwal123@gmail.com>
Cc: "Paul E. McKenney" <paulmck@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently we don't have a way how to determing from which mount point
file has been opened. This information is required for proper dumping
and restoring file descriptos due to presence of mount namespaces. It's
possible, that two file descriptors are opened using the same paths, but
one fd references mount point from one namespace while the other fd --
from other namespace.
$ ls -l /proc/1/fd/1
lrwx------ 1 root root 64 Mar 19 23:54 /proc/1/fd/1 -> /dev/null
$ cat /proc/1/fdinfo/1
pos: 0
flags: 0100002
mnt_id: 16
$ cat /proc/1/mountinfo | grep ^16
16 32 0:4 / /dev rw,nosuid shared:2 - devtmpfs devtmpfs rw,size=1013356k,nr_inodes=253339,mode=755
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Acked-by: Pavel Emelyanov <xemul@parallels.com>
Acked-by: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Rob Landley <rob@landley.net>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
It should read "reclaimable slab" and not "reclaimable swap".
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Acked-by: Rafael Aquini <aquini@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch is a continuation of efforts trying to optimize find_vma(),
avoiding potentially expensive rbtree walks to locate a vma upon faults.
The original approach (https://lkml.org/lkml/2013/11/1/410), where the
largest vma was also cached, ended up being too specific and random,
thus further comparison with other approaches were needed. There are
two things to consider when dealing with this, the cache hit rate and
the latency of find_vma(). Improving the hit-rate does not necessarily
translate in finding the vma any faster, as the overhead of any fancy
caching schemes can be too high to consider.
We currently cache the last used vma for the whole address space, which
provides a nice optimization, reducing the total cycles in find_vma() by
up to 250%, for workloads with good locality. On the other hand, this
simple scheme is pretty much useless for workloads with poor locality.
Analyzing ebizzy runs shows that, no matter how many threads are
running, the mmap_cache hit rate is less than 2%, and in many situations
below 1%.
The proposed approach is to replace this scheme with a small per-thread
cache, maximizing hit rates at a very low maintenance cost.
Invalidations are performed by simply bumping up a 32-bit sequence
number. The only expensive operation is in the rare case of a seq
number overflow, where all caches that share the same address space are
flushed. Upon a miss, the proposed replacement policy is based on the
page number that contains the virtual address in question. Concretely,
the following results are seen on an 80 core, 8 socket x86-64 box:
1) System bootup: Most programs are single threaded, so the per-thread
scheme does improve ~50% hit rate by just adding a few more slots to
the cache.
+----------------+----------+------------------+
| caching scheme | hit-rate | cycles (billion) |
+----------------+----------+------------------+
| baseline | 50.61% | 19.90 |
| patched | 73.45% | 13.58 |
+----------------+----------+------------------+
2) Kernel build: This one is already pretty good with the current
approach as we're dealing with good locality.
+----------------+----------+------------------+
| caching scheme | hit-rate | cycles (billion) |
+----------------+----------+------------------+
| baseline | 75.28% | 11.03 |
| patched | 88.09% | 9.31 |
+----------------+----------+------------------+
3) Oracle 11g Data Mining (4k pages): Similar to the kernel build workload.
+----------------+----------+------------------+
| caching scheme | hit-rate | cycles (billion) |
+----------------+----------+------------------+
| baseline | 70.66% | 17.14 |
| patched | 91.15% | 12.57 |
+----------------+----------+------------------+
4) Ebizzy: There's a fair amount of variation from run to run, but this
approach always shows nearly perfect hit rates, while baseline is just
about non-existent. The amounts of cycles can fluctuate between
anywhere from ~60 to ~116 for the baseline scheme, but this approach
reduces it considerably. For instance, with 80 threads:
+----------------+----------+------------------+
| caching scheme | hit-rate | cycles (billion) |
+----------------+----------+------------------+
| baseline | 1.06% | 91.54 |
| patched | 99.97% | 14.18 |
+----------------+----------+------------------+
[akpm@linux-foundation.org: fix nommu build, per Davidlohr]
[akpm@linux-foundation.org: document vmacache_valid() logic]
[akpm@linux-foundation.org: attempt to untangle header files]
[akpm@linux-foundation.org: add vmacache_find() BUG_ON]
[hughd@google.com: add vmacache_valid_mm() (from Oleg)]
[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: adjust and enhance comments]
Signed-off-by: Davidlohr Bueso <davidlohr@hp.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Reviewed-by: Michel Lespinasse <walken@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Tested-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
