This is a note to let you know that I've just added the patch titled
Prevent rt_sigqueueinfo and rt_tgsigqueueinfo from spoofing the signal code
to the 2.6.32-longterm tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/longterm/longterm-queue-2.6.32.git;a=summary
The filename of the patch is:
prevent-rt_sigqueueinfo-and-rt_tgsigqueueinfo-from-spoofing-the-signal-code.patch
and it can be found in the queue-2.6.32 subdirectory.
If you, or anyone else, feels it should not be added to the 2.6.32 longterm
tree,
please let <[email protected]> know about it.
>From da48524eb20662618854bb3df2db01fc65f3070c Mon Sep 17 00:00:00 2001
From: Julien Tinnes <[email protected]>
Date: Fri, 18 Mar 2011 15:05:21 -0700
Subject: Prevent rt_sigqueueinfo and rt_tgsigqueueinfo from spoofing the signal
code
From: Julien Tinnes <[email protected]>
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 <[email protected]>
Acked-by: Oleg Nesterov <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
kernel/signal.c | 16 ++++++++++++----
1 file changed, 12 insertions(+), 4 deletions(-)
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -2351,9 +2351,13 @@ SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t,
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. */
@@ -2367,9 +2371,13 @@ long do_rt_tgsigqueueinfo(pid_t tgid, pi
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);
Patches currently in longterm-queue-2.6.32 which might be from [email protected]
are
/home/gregkh/linux/longterm/longterm-queue-2.6.32/queue-2.6.32/prevent-rt_sigqueueinfo-and-rt_tgsigqueueinfo-from-spoofing-the-signal-code.patch
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