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signals: send_sigio: use do_send_sig_info() to avoid check_kill_permission() 

group_send_sig_info()->check_kill_permission() assumes that current is the
sender and uses current_cred().

This is not true in send_sigio_to_task() case.  From the security pov the
sender is not current, but the task which did fcntl(F_SETOWN), that is why
we have sigio_perm() which uses the right creds to check.

Fortunately, send_sigio() always sends either SEND_SIG_PRIV or
SI_FROMKERNEL() signal, so check_kill_permission() does nothing.  But
still it would be tidier to avoid this bogus security check and save a
couple of cycles.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: stephane eranian <eranian@googlemail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Oleg Nesterov 2009-09-23 15:57:01 -07:00 committed by Linus Torvalds
parent 4a30debfb7
commit 06f1631a16
1 changed files with 2 additions and 2 deletions
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4
fs/fcntl.c
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@ -461,11 +461,11 @@ static void send_sigio_to_task(struct task_struct *p,
else
si.si_band = band_table[reason - POLL_IN];
si.si_fd = fd;
if (!group_send_sig_info(signum, &si, p))
if (!do_send_sig_info(signum, &si, p, true))
break;
/* fall-through: fall back on the old plain SIGIO signal */
case 0:
group_send_sig_info(SIGIO, SEND_SIG_PRIV, p);
do_send_sig_info(SIGIO, SEND_SIG_PRIV, p, true);
}
}