Messages in this thread Patch in this message | | | Date | Wed, 13 Apr 2011 08:50:41 -0700 | From | Greg KH <> | Subject | [17/74] Relax si_code check in rt_sigqueueinfo and rt_tgsigqueueinfo |
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2.6.32-longterm review patch. If anyone has any objections, please let us know.
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From: Roland Dreier <roland@purestorage.com>
commit 243b422af9ea9af4ead07a8ad54c90d4f9b6081a upstream.
Commit da48524eb206 ("Prevent rt_sigqueueinfo and rt_tgsigqueueinfo from spoofing the signal code") made the check on si_code too strict. There are several legitimate places where glibc wants to queue a negative si_code different from SI_QUEUE:
- This was first noticed with glibc's aio implementation, which wants to queue a signal with si_code SI_ASYNCIO; the current kernel causes glibc's tst-aio4 test to fail because rt_sigqueueinfo() fails with EPERM.
- Further examination of the glibc source shows that getaddrinfo_a() wants to use SI_ASYNCNL (which the kernel does not even define). The timer_create() fallback code wants to queue signals with SI_TIMER.
As suggested by Oleg Nesterov <oleg@redhat.com>, loosen the check to forbid only the problematic SI_TKILL case.
Reported-by: Klaus Dittrich <kladit@arcor.de> Acked-by: Julien Tinnes <jln@google.com> Signed-off-by: Roland Dreier <roland@purestorage.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- kernel/signal.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
--- a/kernel/signal.c +++ b/kernel/signal.c @@ -2353,7 +2353,7 @@ SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, /* Not even root can pretend to send signals from the kernel. * Nor can they impersonate a kill()/tgkill(), which adds source info. */ - if (info.si_code != SI_QUEUE) { + if (info.si_code >= 0 || info.si_code == SI_TKILL) { /* We used to allow any < 0 si_code */ WARN_ON_ONCE(info.si_code < 0); return -EPERM; @@ -2373,7 +2373,7 @@ long do_rt_tgsigqueueinfo(pid_t tgid, pi /* Not even root can pretend to send signals from the kernel. * Nor can they impersonate a kill()/tgkill(), which adds source info. */ - if (info->si_code != SI_QUEUE) { + if (info->si_code >= 0 || info->si_code == SI_TKILL) { /* We used to allow any < 0 si_code */ WARN_ON_ONCE(info->si_code < 0); return -EPERM;
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