linux-stable.git/ipc/util.c, branch linux-3.16.y

ipc/util: Helpers for making the sysvipc operations pid namespace aware

2018-10-21T07:45:02+00:00

commit 03f1fc09180b345582889a344b012d069b3a6dbe upstream.

Capture the pid namespace when /proc/sysvipc/msg /proc/sysvipc/shm
and /proc/sysvipc/sem are opened, and make it available through
the new helper ipc_seq_pid_ns.

This makes it possible to report the pids in these files in the
pid namespace of the opener of the files.

Implement ipc_update_pid.  A simple impline helper that will only update
a struct pid pointer if the new value does not equal the old value.  This
removes the need for wordy code sequences like:

	old = object->pid;
	object->pid = new;
	put_pid(old);

and

	old = object->pid;
	if (old != new) {
		object->pid = new;
		put_pid(old);
	}

Allowing the following to be written instead:

	ipc_update_pid(&object->pid, new);

Which is easier to read and ensures that the pid reference count is
not touched the old and the new values are the same.  Not touching
the reference count in this case is important to help avoid issues
like af_unix experienced, where multiple threads of the same
process managed to bounce the struct pid between cpu cache lines,
but updating the pids reference count.

Signed-off-by: "Eric W. Biederman" 
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings

ipc: remove use of seq_printf return value

2017-02-23T03:54:11+00:00

commit 7f032d6ef6154868a2a5d5f6b2c3f8587292196c upstream.

The seq_printf return value, because it's frequently misused,
will eventually be converted to void.

See: commit 1f33c41c03da ("seq_file: Rename seq_overflow() to
     seq_has_overflowed() and make public")

Signed-off-by: Joe Perches 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Ben Hutchings

Initialize msg/shm IPC objects before doing ipc_addid()

2015-10-28T10:33:06+00:00

commit b9a532277938798b53178d5a66af6e2915cb27cf upstream.

As reported by Dmitry Vyukov, we really shouldn't do ipc_addid() before
having initialized the IPC object state.  Yes, we initialize the IPC
object in a locked state, but with all the lockless RCU lookup work,
that IPC object lock no longer means that the state cannot be seen.

We already did this for the IPC semaphore code (see commit e8577d1f0329:
"ipc/sem.c: fully initialize sem_array before making it visible") but we
clearly forgot about msg and shm.

Reported-by: Dmitry Vyukov 
Cc: Manfred Spraul 
Cc: Davidlohr Bueso 
Signed-off-by: Linus Torvalds 
[ luis: backported to 3.16: adjusted context ]
Signed-off-by: Luis Henriques

ipc, kernel: clear whitespace

2014-06-06T23:08:14+00:00

trailing whitespace

Signed-off-by: Paul McQuade 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

ipc: constify ipc_ops

2014-06-06T23:08:14+00:00

There is no need to recreate the very same ipc_ops structure on every
kernel entry for msgget/semget/shmget.  Just declare it static and be
done with it.  While at it, constify it as we don't modify the structure
at runtime.

Found in the PaX patch, written by the PaX Team.

Signed-off-by: Mathias Krause 
Cc: PaX Team 
Cc: Davidlohr Bueso 
Cc: Manfred Spraul 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

ipc: use device_initcall

2014-04-07T23:36:11+00:00

... since __initcall is now deprecated.

Signed-off-by: Davidlohr Bueso 
Cc: Manfred Spraul 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

ipc: delete seq_max field in struct ipc_ids

2014-01-28T05:02:40+00:00

This field is only used to reset the ids seq number if it exceeds the
smaller of INT_MAX/SEQ_MULTIPLIER and USHRT_MAX, and can therefore be
moved out of the structure and into its own macro.  Since each
ipc_namespace contains a table of 3 pointers to struct ipc_ids we can
save space in instruction text:

   text    data     bss     dec     hex filename
  56232    2348      24   58604    e4ec ipc/built-in.o
  56216    2348      24   58588    e4dc ipc/built-in.o-after

Signed-off-by: Davidlohr Bueso 
Reviewed-by: Jonathan Gonzalez 
Cc: Aswin Chandramouleeswaran 
Cc: Rik van Riel 
Acked-by: Manfred Spraul 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

ipc: simplify sysvipc_proc_open() return

2014-01-28T05:02:40+00:00

Get rid of silly/useless label jumping.

Signed-off-by: Davidlohr Bueso 
Cc: Aswin Chandramouleeswaran 
Cc: Rik van Riel 
Acked-by: Manfred Spraul 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

ipc: remove useless return statement

2014-01-28T05:02:40+00:00

Only found in ipc_rmid().

Signed-off-by: Davidlohr Bueso 
Cc: Aswin Chandramouleeswaran 
Cc: Rik van Riel 
Acked-by: Manfred Spraul 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

ipc: remove braces for single statements

2014-01-28T05:02:39+00:00

Deal with checkpatch messages:
     WARNING: braces {} are not necessary for single statement blocks

Signed-off-by: Davidlohr Bueso 
Cc: Aswin Chandramouleeswaran 
Cc: Rik van Riel 
Acked-by: Manfred Spraul 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds