linux.git/fs/exec.c, branch v2.6.26-rc2

[PATCH] split linux/file.h

2008-05-01T17:08:16+00:00

Initial splitoff of the low-level stuff; taken to fdtable.h

Signed-off-by: Al Viro

document de_thread() with exit_notify() connection

2008-04-30T15:29:38+00:00

Add a couple of small comments, it is not easy to see what this code does.

Signed-off-by: Oleg Nesterov 
Cc: Roland McGrath 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

signals: de_thread: simplify the ->child_reaper switching

2008-04-30T15:29:37+00:00

Now that we rely on SIGNAL_UNKILLABLE flag, de_thread() doesn't need the nasty
hack to kill the old ->child_reaper during the mt-exec.

This also means we can avoid taking tasklist_lock around zap_other_threads().

Signed-off-by: Oleg Nesterov 
Cc: Roland McGrath 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

procfs task exe symlink

2008-04-29T15:06:17+00:00

The kernel implements readlink of /proc/pid/exe by getting the file from
the first executable VMA.  Then the path to the file is reconstructed and
reported as the result.

Because of the VMA walk the code is slightly different on nommu systems.
This patch avoids separate /proc/pid/exe code on nommu systems.  Instead of
walking the VMAs to find the first executable file-backed VMA we store a
reference to the exec'd file in the mm_struct.

That reference would prevent the filesystem holding the executable file
from being unmounted even after unmapping the VMAs.  So we track the number
of VM_EXECUTABLE VMAs and drop the new reference when the last one is
unmapped.  This avoids pinning the mounted filesystem.

[akpm@linux-foundation.org: improve comments]
[yamamoto@valinux.co.jp: fix dup_mmap]
Signed-off-by: Matt Helsley 
Cc: Oleg Nesterov 
Cc: David Howells 
Cc:"Eric W. Biederman" 
Cc: Christoph Hellwig 
Cc: Al Viro 
Cc: Hugh Dickins 
Signed-off-by: YAMAMOTO Takashi 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

cgroups: add an owner to the mm_struct

2008-04-29T15:06:10+00:00

Remove the mem_cgroup member from mm_struct and instead adds an owner.

This approach was suggested by Paul Menage.  The advantage of this approach
is that, once the mm->owner is known, using the subsystem id, the cgroup
can be determined.  It also allows several control groups that are
virtually grouped by mm_struct, to exist independent of the memory
controller i.e., without adding mem_cgroup's for each controller, to
mm_struct.

A new config option CONFIG_MM_OWNER is added and the memory resource
controller selects this config option.

This patch also adds cgroup callbacks to notify subsystems when mm->owner
changes.  The mm_cgroup_changed callback is called with the task_lock() of
the new task held and is called just prior to changing the mm->owner.

I am indebted to Paul Menage for the several reviews of this patchset and
helping me make it lighter and simpler.

This patch was tested on a powerpc box, it was compiled with both the
MM_OWNER config turned on and off.

After the thread group leader exits, it's moved to init_css_state by
cgroup_exit(), thus all future charges from runnings threads would be
redirected to the init_css_set's subsystem.

Signed-off-by: Balbir Singh 
Cc: Pavel Emelianov 
Cc: Hugh Dickins 
Cc: Sudhir Kumar 
Cc: YAMAMOTO Takashi 
Cc: Hirokazu Takahashi 
Cc: David Rientjes ,
Cc: Balbir Singh 
Acked-by: KAMEZAWA Hiroyuki 
Acked-by: Pekka Enberg 
Reviewed-by: Paul Menage 
Cc: Oleg Nesterov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

exec: remove argv_len from struct linux_binprm

2008-04-29T15:06:03+00:00

I noticed that 2.6.24.2 calculates bprm->argv_len at do_execve().  But it
doesn't update bprm->argv_len after "remove_arg_zero() +
copy_strings_kernel()" at load_script() etc.

audit_bprm() is called from search_binary_handler() and
search_binary_handler() is called from load_script() etc.  Thus, I think the
condition check

  if (bprm->argv_len > (audit_argv_kb << 10))
          return -E2BIG;

in audit_bprm() might return wrong result when strlen(removed_arg) !=
strlen(spliced_args).  Why not update bprm->argv_len at load_script() etc.  ?

By the way, 2.6.25-rc3 seems to not doing the condition check.  Is the field
bprm->argv_len no longer needed?

Signed-off-by: Tetsuo Handa 
Cc: Ollie Wild 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] sanitize unshare_files/reset_files_struct

2008-04-25T13:23:59+00:00

* let unshare_files() give caller the displaced files_struct
* don't bother with grabbing reference only to drop it in the
  caller if it hadn't been shared in the first place
* in that form unshare_files() is trivially implemented via
  unshare_fd(), so we eliminate the duplicate logics in fork.c
* reset_files_struct() is not just only called for current;
  it will break the system if somebody ever calls it for anything
  else (we can't modify ->files of somebody else).  Lose the
  task_struct * argument.

Signed-off-by: Al Viro

[PATCH] sanitize handling of shared descriptor tables in failing execve()

2008-04-25T13:23:53+00:00

* unshare_files() can fail; doing it after irreversible actions is wrong
  and de_thread() is certainly irreversible.
* since we do it unconditionally anyway, we might as well do it in do_execve()
  and save ourselves the PITA in binfmt handlers, etc.
* while we are at it, binfmt_som actually leaked files_struct on failure.

As a side benefit, unshare_files(), put_files_struct() and reset_files_struct()
become unexported.

Signed-off-by: Al Viro

Allow ARG_MAX execve string space even with a small stack limit

2008-03-03T18:12:14+00:00

The new code that removed the limitation on the execve string size
(which was historically 32 pages) replaced it with a much softer limit
based on RLIMIT_STACK which is usually much larger than the traditional
limit.  See commit b6a2fea39318e43fee84fa7b0b90d68bed92d2ba ("mm:
variable length argument support") for details.

However, if you have a small stack limit (perhaps because you need lots
of stacks in a threaded environment), the new heuristic of allowing up
to 1/4th of RLIMIT_STACK to be used for argument and environment strings
could actually be smaller than the old limit.

So just say that it's ok to have up to ARG_MAX strings regardless of the
value of RLIMIT_STACK, and check the rlimit only when going over that
traditional limit.

(Of course, if you actually have a *really* small stack limit, the whole
stack itself will be limited before you hit ARG_MAX, but that has always
been true and is clearly the right behaviour anyway).

Acked-by: Carlos O'Donell 
Cc: Michael Kerrisk 
Cc: Peter Zijlstra 
Cc: Ollie Wild 
Signed-off-by: Linus Torvalds

Introduce path_put()

2008-02-15T05:13:33+00:00

* Add path_put() functions for releasing a reference to the dentry and
  vfsmount of a struct path in the right order

* Switch from path_release(nd) to path_put(&nd->path)

* Rename dput_path() to path_put_conditional()

[akpm@linux-foundation.org: fix cifs]
Signed-off-by: Jan Blunck 
Signed-off-by: Andreas Gruenbacher 
Acked-by: Christoph Hellwig 
Cc: 
Cc: Al Viro 
Cc: Steven French 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds