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authorOleg Nesterov <oleg@tv-sign.ru>2008-04-30 00:52:42 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2008-04-30 08:29:34 -0700
commit3b5e9e53c6f31b5a5a0f5c43707503c62bdefa46 (patch)
tree1244b7cf2755c06a8a793149ce4717e4a1311218 /kernel/signal.c
parent9e3bd6c3fb2334be171e69b432039cd18bce4458 (diff)
downloadlinux-2.6.38-lt-ux500-3b5e9e53c6f31b5a5a0f5c43707503c62bdefa46.tar.gz
signals: cleanup security_task_kill() usage/implementation
Every implementation of ->task_kill() does nothing when the signal comes from the kernel. This is correct, but means that check_kill_permission() should call security_task_kill() only for SI_FROMUSER() case, and we can remove the same check from ->task_kill() implementations. (sadly, check_kill_permission() is the last user of signal->session/__session but we can't s/task_session_nr/task_session/ here). NOTE: Eric W. Biederman pointed out cap_task_kill() should die, and I think he is very right. Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Serge Hallyn <serue@us.ibm.com> Cc: Roland McGrath <roland@redhat.com> Cc: Casey Schaufler <casey@schaufler-ca.com> Cc: David Quigley <dpquigl@tycho.nsa.gov> Cc: Eric Paris <eparis@redhat.com> Cc: Harald Welte <laforge@gnumonks.org> Cc: Pavel Emelyanov <xemul@openvz.org> Cc: Stephen Smalley <sds@tycho.nsa.gov> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/signal.c')
-rw-r--r--kernel/signal.c27
1 files changed, 14 insertions, 13 deletions
diff --git a/kernel/signal.c b/kernel/signal.c
index f9a52c72127..91d57f89f5a 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -533,22 +533,23 @@ static int rm_from_queue(unsigned long mask, struct sigpending *s)
static int check_kill_permission(int sig, struct siginfo *info,
struct task_struct *t)
{
- int error = -EINVAL;
+ int error;
+
if (!valid_signal(sig))
- return error;
+ return -EINVAL;
- if (info == SEND_SIG_NOINFO || (!is_si_special(info) && SI_FROMUSER(info))) {
- error = audit_signal_info(sig, t); /* Let audit system see the signal */
- if (error)
- return error;
- error = -EPERM;
- if (((sig != SIGCONT) ||
- (task_session_nr(current) != task_session_nr(t)))
- && (current->euid ^ t->suid) && (current->euid ^ t->uid)
- && (current->uid ^ t->suid) && (current->uid ^ t->uid)
- && !capable(CAP_KILL))
+ if (info != SEND_SIG_NOINFO && (is_si_special(info) || SI_FROMKERNEL(info)))
+ return 0;
+
+ error = audit_signal_info(sig, t); /* Let audit system see the signal */
+ if (error)
return error;
- }
+
+ if (((sig != SIGCONT) || (task_session_nr(current) != task_session_nr(t)))
+ && (current->euid ^ t->suid) && (current->euid ^ t->uid)
+ && (current->uid ^ t->suid) && (current->uid ^ t->uid)
+ && !capable(CAP_KILL))
+ return -EPERM;
return security_task_kill(t, info, sig, 0);
}