tree baf03552245a447e8fb92b68f93a515a0996e0b3
parent 12013f28feb76d142d78730e928af2436c5df9b9
author Julien Tinnes <jln@google.com> 1300485921 -0700
committer Willy Tarreau <w@1wt.eu> 1333975191 +0200
encoding latin1

Prevent rt_sigqueueinfo and rt_tgsigqueueinfo from spoofing the signal code

Userland should be able to trust the pid and uid of the sender of a
signal if the si_code is SI_TKILL.

Unfortunately, the kernel has historically allowed sigqueueinfo() to
send any si_code at all (as long as it was negative - to distinguish it
from kernel-generated signals like SIGILL etc), so it could spoof a
SI_TKILL with incorrect siginfo values.

Happily, it looks like glibc has always set si_code to the appropriate
SI_QUEUE, so there are probably no actual user code that ever uses
anything but the appropriate SI_QUEUE flag.

So just tighten the check for si_code (we used to allow any negative
value), and add a (one-time) warning in case there are binaries out
there that might depend on using other si_code values.

Signed-off-by: Julien Tinnes <jln@google.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[ WT: removed the WARN_ON_ONCE() which is not available in 2.4 and not critical ]
Signed-off-by: Willy Tarreau <w@1wt.eu>