diff options
| author | Julien Tinnes <jln@google.com> | 2011-03-18 15:05:21 -0700 |
|---|---|---|
| committer | Willy Tarreau <w@1wt.eu> | 2012-04-09 14:39:51 +0200 |
| commit | db7bb51987c369ff0b356061385bc03c85ee5511 (patch) | |
| tree | baf03552245a447e8fb92b68f93a515a0996e0b3 | |
| parent | 12013f28feb76d142d78730e928af2436c5df9b9 (diff) | |
| download | linux-2.4-db7bb51987c369ff0b356061385bc03c85ee5511.tar.gz | |
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>
| -rw-r--r-- | kernel/signal.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/kernel/signal.c b/kernel/signal.c index e392acc547283..b368505a7b22f 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -1074,9 +1074,12 @@ sys_rt_sigqueueinfo(int pid, int sig, siginfo_t *uinfo) return -EFAULT; /* Not even root can pretend to send signals from the kernel. - Nor can they impersonate a kill(), which adds source info. */ - if (info.si_code >= 0) + * Nor can they impersonate a kill()/tgkill(), which adds source info. + */ + if (info.si_code != SI_QUEUE) { + /* We used to allow any < 0 si_code */ return -EPERM; + } info.si_signo = sig; /* POSIX.1b doesn't mention process groups. */ |