We end up trying to kfree() nd.last.name on open("/mnt/tmp", O_CREAT)
if /mnt/tmp is an autofs direct mount. The reason is that nd.last_type
is bogus here; we want LAST_BIND for everything of that kind and we
get LAST_NORM left over from finding parent directory.
So make sure that it *is* set properly; set to LAST_BIND before
doing ->follow_link() - for normal symlinks it will be changed
by __vfs_follow_link() and everything else needs it set that way.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Setting a thread's comm to be something unique is a very useful ability
and is helpful for debugging complicated threaded applications. However
currently the only way to set a thread name is for the thread to name
itself via the PR_SET_NAME prctl.
However, there may be situations where it would be advantageous for a
thread dispatcher to be naming the threads its managing, rather then
having the threads self-describe themselves. This sort of behavior is
available on other systems via the pthread_setname_np() interface.
This patch exports a task's comm via proc/pid/comm and
proc/pid/task/tid/comm interfaces, and allows thread siblings to write to
these values.
[akpm@linux-foundation.org: cleanups]
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Mike Fulton <fultonm@ca.ibm.com>
Cc: Sean Foley <Sean_Foley@ca.ibm.com>
Cc: Darren Hart <dvhltc@us.ibm.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Daniel Lezcano reported a leak in 'struct pid' and 'struct pid_namespace'
that is discussed in:
http://lkml.org/lkml/2009/10/2/159.
To summarize the thread, when container-init is terminated, it sets the
PF_EXITING flag, zaps other processes in the container and waits to reap
them. As a part of reaping, the container-init should flush any /proc
dentries associated with the processes. But because the container-init is
itself exiting and the following PF_EXITING check, the dentries are not
flushed, resulting in leak in /proc inodes and dentries.
This fix reverts the commit 7766755a2f ("Fix /proc dcache deadlock
in do_exit") which introduced the check for PF_EXITING. At the time of
the commit, shrink_dcache_parent() flushed dentries from other filesystems
also and could have caused a deadlock which the commit fixed. But as
pointed out by Eric Biederman, after commit 0feae5c47a,
shrink_dcache_parent() no longer affects other filesystems. So reverting
the commit is now safe.
As pointed out by Jan Kara, the leak is not as critical since the
unclaimed space will be reclaimed under memory pressure or by:
echo 3 > /proc/sys/vm/drop_caches
But since this check is no longer required, its best to remove it.
Signed-off-by: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Reported-by: Daniel Lezcano <dlezcano@fr.ibm.com>
Acked-by: Eric W. Biederman <ebiederm@xmission.com>
Acked-by: Jan Kara <jack@ucw.cz>
Cc: Andrea Arcangeli <andrea@cpushare.com>
Cc: Serge Hallyn <serue@us.ibm.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Remove obfuscated zero-length input check and return -EINVAL instead of
-EIO error to make the error message clear to user. Add whitespace
stripping. No functionality changes.
The old code:
echo 1 > /proc/pid/make-it-fail (ok)
echo 1foo > /proc/pid/make-it-fail (-bash: echo: write error: Input/output error)
The new code:
echo 1 > /proc/pid/make-it-fail (ok)
echo 1foo > /proc/pid/make-it-fail (-bash: echo: write error: Invalid argument)
This patch is conservative in changes to not breaking existing
scripts/applications.
Signed-off-by: Vincent Li <macli@brc.ubc.ca>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The exiting sub-thread flushes /proc/pid only, but this doesn't buy too
much: ps and friends mostly use /proc/tid/task/pid.
Remove "if (thread_group_leader())" checks from proc_flush_task() path,
this means we always remove /proc/tid/task/pid dentry on exit, and this
actually matches the comment above proc_flush_task().
The test-case:
static void* tfunc(void *arg)
{
char name[256];
sprintf(name, "/proc/%d/task/%ld/status", getpid(), gettid());
close(open(name, O_RDONLY));
return NULL;
}
int main(void)
{
pthread_t t;
for (;;) {
if (!pthread_create(&t, NULL, &tfunc, NULL))
pthread_join(t, NULL);
}
}
slabtop shows that pid/proc_inode_cache/etc grow quickly and
"indefinitely" until the task is killed or shrink_slab() is called, not
good. And the main thread needs a lot of time to exit.
The same can happen if something like "ps -efL" runs continuously, while
some application spawns short-living threads.
Reported-by: "James M. Leddy" <jleddy@redhat.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Dominic Duval <dduval@redhat.com>
Cc: Frank Hirtz <fhirtz@redhat.com>
Cc: "Fuller, Johnray" <Johnray.Fuller@gs.com>
Cc: Larry Woodman <lwoodman@redhat.com>
Cc: Paul Batkowski <pbatkowski@redhat.com>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
/proc/$pid/limits should show RLIMIT_CPU as seconds, which is the unit
used in kernel/posix-cpu-timers.c:
unsigned long psecs = cputime_to_secs(ptime);
...
if (psecs >= sig->rlim[RLIMIT_CPU].rlim_max) {
...
__group_send_sig_info(SIGKILL, SEND_SIG_PRIV, tsk);
Signed-off-by: Kees Cook <kees.cook@canonical.com>
Acked-by: WANG Cong <xiyou.wangcong@gmail.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently, OOM logic callflow is here.
__out_of_memory()
select_bad_process() for each task
badness() calculate badness of one task
oom_kill_process() search child
oom_kill_task() kill target task and mm shared tasks with it
example, process-A have two thread, thread-A and thread-B and it have very
fat memory and each thread have following oom_adj and oom_score.
thread-A: oom_adj = OOM_DISABLE, oom_score = 0
thread-B: oom_adj = 0, oom_score = very-high
Then, select_bad_process() select thread-B, but oom_kill_task() refuse
kill the task because thread-A have OOM_DISABLE. Thus __out_of_memory()
call select_bad_process() again. but select_bad_process() select the same
task. It mean kernel fall in livelock.
The fact is, select_bad_process() must select killable task. otherwise
OOM logic go into livelock.
And root cause is, oom_adj shouldn't be per-thread value. it should be
per-process value because OOM-killer kill a process, not thread. Thus
This patch moves oomkilladj (now more appropriately named oom_adj) from
struct task_struct to struct signal_struct. it naturally prevent
select_bad_process() choose wrong task.
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Paul Menage <menage@google.com>
Cc: David Rientjes <rientjes@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The commit 2ff05b2b (oom: move oom_adj value) moveed the oom_adj value to
the mm_struct. It was a very good first step for sanitize OOM.
However Paul Menage reported the commit makes regression to his job
scheduler. Current OOM logic can kill OOM_DISABLED process.
Why? His program has the code of similar to the following.
...
set_oom_adj(OOM_DISABLE); /* The job scheduler never killed by oom */
...
if (vfork() == 0) {
set_oom_adj(0); /* Invoked child can be killed */
execve("foo-bar-cmd");
}
....
vfork() parent and child are shared the same mm_struct. then above
set_oom_adj(0) doesn't only change oom_adj for vfork() child, it's also
change oom_adj for vfork() parent. Then, vfork() parent (job scheduler)
lost OOM immune and it was killed.
Actually, fork-setting-exec idiom is very frequently used in userland program.
We must not break this assumption.
Then, this patch revert commit 2ff05b2b and related commit.
Reverted commit list
---------------------
- commit 2ff05b2b4e (oom: move oom_adj value from task_struct to mm_struct)
- commit 4d8b9135c3 (oom: avoid unnecessary mm locking and scanning for OOM_DISABLE)
- commit 8123681022 (oom: only oom kill exiting tasks with attached memory)
- commit 933b787b57 (mm: copy over oom_adj value at fork time)
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Paul Menage <menage@google.com>
Cc: David Rientjes <rientjes@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Nick Piggin <npiggin@suse.de>
Cc: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The problem is minor, but without ->cred_guard_mutex held we can race
with exec() and get the new ->mm but check old creds.
Now we do not need to re-check task->mm after ptrace_may_access(), it
can't be changed to the new mm under us.
Strictly speaking, this also fixes another very minor problem. Unless
security check fails or the task exits mm_for_maps() should never
return NULL, the caller should get either old or new ->mm.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>
mm_for_maps() takes ->mmap_sem after security checks, this looks
strange and obfuscates the locking rules. Move this lock to its
single caller, m_start().
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>
It would be nice to kill __ptrace_may_access(). It requires task_lock(),
but this lock is only needed to read mm->flags in the middle.
Convert mm_for_maps() to use ptrace_may_access(), this also simplifies
the code a little bit.
Also, we do not need to take ->mmap_sem in advance. In fact I think
mm_for_maps() should not play with ->mmap_sem at all, the caller should
take this lock.
With or without this patch, without ->cred_guard_mutex held we can race
with exec() and get the new ->mm but check old creds.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>
The per-task oom_adj value is a characteristic of its mm more than the
task itself since it's not possible to oom kill any thread that shares the
mm. If a task were to be killed while attached to an mm that could not be
freed because another thread were set to OOM_DISABLE, it would have
needlessly been terminated since there is no potential for future memory
freeing.
This patch moves oomkilladj (now more appropriately named oom_adj) from
struct task_struct to struct mm_struct. This requires task_lock() on a
task to check its oom_adj value to protect against exec, but it's already
necessary to take the lock when dereferencing the mm to find the total VM
size for the badness heuristic.
This fixes a livelock if the oom killer chooses a task and another thread
sharing the same memory has an oom_adj value of OOM_DISABLE. This occurs
because oom_kill_task() repeatedly returns 1 and refuses to kill the
chosen task while select_bad_process() will repeatedly choose the same
task during the next retry.
Taking task_lock() in select_bad_process() to check for OOM_DISABLE and in
oom_kill_task() to check for threads sharing the same memory will be
removed in the next patch in this series where it will no longer be
necessary.
Writing to /proc/pid/oom_adj for a kthread will now return -EINVAL since
these threads are immune from oom killing already. They simply report an
oom_adj value of OOM_DISABLE.
Cc: Nick Piggin <npiggin@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
proc_pident_instantiate() has following call flow.
proc_pident_lookup()
proc_pident_instantiate()
proc_pid_make_inode()
And, proc_pident_lookup() has following error handling.
const struct pid_entry *p, *last;
error = ERR_PTR(-ENOENT);
if (!task)
goto out_no_task;
Then, proc_pident_instantiate should return ENOENT too when racing against
exit(2) occur.
EINAL has two bad reason.
- it implies caller is wrong. bad the race isn't caller's mistake.
- man 2 open don't explain EINVAL. user often don't handle it.
Note: Other proc_pid_make_inode() caller already use ENOENT properly.
Acked-by: Eric W. Biederman <ebiederm@xmission.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Guard the setprocattr security hook against ptrace by taking the target task's
cred_guard_mutex around it. The problem is that setprocattr() may otherwise
note the lack of a debugger, and then perform an action on that basis whilst
letting a debugger attach between the two points. Holding cred_guard_mutex
across the test and the action prevents ptrace_attach() from doing that.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>
By using the same test as is used for /proc/pid/maps and /proc/pid/smaps,
only allow processes that can ptrace() a given process to see information
that might be used to bypass address space layout randomization (ASLR).
These include eip, esp, wchan, and start_stack in /proc/pid/stat as well
as the non-symbolic output from /proc/pid/wchan.
ASLR can be bypassed by sampling eip as shown by the proof-of-concept
code at http://code.google.com/p/fuzzyaslr/ As part of a presentation
(http://www.cr0.org/paper/to-jt-linux-alsr-leak.pdf) esp and wchan were
also noted as possibly usable information leaks as well. The
start_stack address also leaks potentially useful information.
Cc: Stable Team <stable@kernel.org>
Signed-off-by: Jake Edge <jake@lwn.net>
Acked-by: Arjan van de Ven <arjan@linux.intel.com>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In recently sysfs_poll discussion, Neil Brown pointed out /proc/mounts
also should be fixed.
SUSv3 says "Regular files shall always poll TRUE for reading and
writing". see
http://www.opengroup.org/onlinepubs/009695399/functions/poll.html
Then, mounts_poll()'s default should be "POLLIN | POLLRDNORM". it mean
always readable.
In addition, event trigger should use "POLLERR | POLLPRI" instead
POLLERR. it makes consistent to mdstat_poll() and sysfs_poll(). and,
select(2) can handle POLLPRI easily.
Reported-by: Neil Brown <neilb@suse.de>
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Ram Pai <linuxram@us.ibm.com>
Cc: Miklos Szeredi <mszeredi@suse.cz>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Don't pull it in sched.h; very few files actually need it and those
can include directly. sched.h itself only needs forward declaration
of struct fs_struct;
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
check_unsafe_exec() also notes whether the fs_struct is being
shared by more threads than will get killed by the exec, and if so
sets LSM_UNSAFE_SHARE to make bprm_set_creds() careful about euid.
But /proc/<pid>/cwd and /proc/<pid>/root lookups make transient
use of get_fs_struct(), which also raises that sharing count.
This might occasionally cause a setuid program not to change euid,
in the same way as happened with files->count (check_unsafe_exec
also looks at sighand->count, but /proc doesn't raise that one).
We'd prefer exec not to unshare fs_struct: so fix this in procfs,
replacing get_fs_struct() by get_fs_path(), which does path_get
while still holding task_lock, instead of raising fs->count.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Cc: stable@kernel.org
___
fs/proc/base.c | 50 +++++++++++++++--------------------------------
1 file changed, 16 insertions(+), 34 deletions(-)
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
