diff options
| author | Julien Tinnes <jln@google.com> | 2011-03-18 15:05:21 -0700 |
|---|---|---|
| committer | Paul Gortmaker <paul.gortmaker@windriver.com> | 2011-04-17 16:16:17 -0400 |
| commit | 9eab773eb3eda5d8336a8f0ac68c5e1faa5f88d5 (patch) | |
| tree | 5e52a82110c71363710603b85b1e96dd240c7a5e | |
| parent | c95610ef5cf44dcef45434ca6de0832aa9b02708 (diff) | |
Prevent rt_sigqueueinfo and rt_tgsigqueueinfo from spoofing the signal code
commit da48524eb20662618854bb3df2db01fc65f3070c upstream.
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>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
| -rw-r--r-- | kernel/signal.c | 16 |
1 files changed, 12 insertions, 4 deletions
diff --git a/kernel/signal.c b/kernel/signal.c index edabc2f910b..704c03089f2 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -2409,9 +2409,13 @@ SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig, 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 */ + WARN_ON_ONCE(info.si_code < 0); return -EPERM; + } info.si_signo = sig; /* POSIX.1b doesn't mention process groups. */ @@ -2425,9 +2429,13 @@ long do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, siginfo_t *info) return -EINVAL; /* 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 */ + WARN_ON_ONCE(info->si_code < 0); return -EPERM; + } info->si_signo = sig; return do_send_specific(tgid, pid, sig, info); |