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CVE-2011-1182: kernel signal spoofing issue

This commit is contained in:
Chuck Ebbert 2011-03-25 10:15:57 -04:00
parent 6236c85dc6
commit 06ad6a4c25
2 changed files with 74 additions and 1 deletions
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11
kernel.spec
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@ -51,7 +51,7 @@ Summary: The Linux kernel
# For non-released -rc kernels, this will be prepended with "0.", so
# for example a 3 here will become 0.3
#
%global baserelease 6
%global baserelease 7
%global fedora_build %{baserelease}
# base_sublevel is the kernel version we're starting with and patching
@ -738,6 +738,9 @@ Patch12421: fs-call-security_d_instantiate-in-d_obtain_alias.patch
# Fix possible memory corruption on Dell HW
Patch12430: dcdbas-force-smi-to-happen-when-expected.patch
# CVE-2011-1182
Patch12431: prevent-rt_sigqueueinfo-and-rt_tgsigqueueinfo-from-spoofing-the-signal-code.patch
%endif
BuildRoot: %{_tmppath}/kernel-%{KVERREL}-root
@ -1372,6 +1375,9 @@ ApplyPatch fs-call-security_d_instantiate-in-d_obtain_alias.patch
# Fix possible memory corruption on Dell HW
ApplyPatch dcdbas-force-smi-to-happen-when-expected.patch
# CVE-2011-1182
ApplyPatch prevent-rt_sigqueueinfo-and-rt_tgsigqueueinfo-from-spoofing-the-signal-code.patch
# END OF PATCH APPLICATIONS
%endif
@ -1980,6 +1986,9 @@ fi
# and build.
%changelog
* Fri Mar 25 2011 Chuck Ebbert <cebbert@redhat.com>
- CVE-2011-1182: kernel signal spoofing issue
* Wed Mar 23 2011 Chuck Ebbert <cebbert@redhat.com> 2.6.38.1-6
- Linux 2.6.38.1
- Drop linux-2.6-ehci-check-port-status.patch, merged in .38.1

64
prevent-rt_sigqueueinfo-and-rt_tgsigqueueinfo-from-spoofing-the-signal-code.patch Normal file
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@ -0,0 +1,64 @@
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);