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 <firstname.lastname@example.org>
Acked-by: Oleg Nesterov <email@example.com>
Signed-off-by: Linus Torvalds <firstname.lastname@example.org>
[ WT: removed the WARN_ON_ONCE() which is not available in 2.4 and not critical ]
Signed-off-by: Willy Tarreau <email@example.com>
1 file changed