65 lines
2.4 KiB
Diff
65 lines
2.4 KiB
Diff
From: Julien Tinnes <jln@google.com>
|
|
Date: Fri, 18 Mar 2011 22:05:21 +0000 (-0700)
|
|
Subject: Prevent rt_sigqueueinfo and rt_tgsigqueueinfo from spoofing the signal code
|
|
X-Git-Url: http://git.kernel.org/?p=linux%2Fkernel%2Fgit%2Ftorvalds%2Flinux-2.6.git;a=commitdiff_plain;h=da48524eb20662618854bb3df2db01fc65f3070c
|
|
|
|
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>
|
|
---
|
|
|
|
diff --git a/kernel/signal.c b/kernel/signal.c
|
|
index 4e3cff1..3175186 100644
|
|
--- a/kernel/signal.c
|
|
+++ b/kernel/signal.c
|
|
@@ -2421,9 +2421,13 @@ 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. */
|
|
@@ -2437,9 +2441,13 @@ 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);
|