lkml.org 
[lkml]   [2009]   [Apr]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
SubjectRe: Q: selinux_bprm_committed_creds() && signals/do_wait
Date
Oleg Nesterov <oleg@redhat.com> wrote:

> No need to check ->shared_pending + ->pending. We can't have SIGKILL
> (shared or not) without SIGNAL_GROUP_EXIT.

Okay, I didn't realise we did this now.

How about the attached patch then?

David
---
From: David Howells <dhowells@redhat.com>
Subject: [PATCH] SELinux: Don't flush inherited SIGKILL during execve()

Don't flush inherited SIGKILL during execve() in SELinux's post cred commit
hook. This isn't really a security problem: if the SIGKILL came before the
credentials were changed, then we were right to receive it at the time, and
should honour it; if it came after the creds were changed, then we definitely
should honour it; and in any case, all that will happen is that the process
will be scrapped before it ever returns to userspace.

Signed-off-by: David Howells <dhowells@redhat.com>
---

include/linux/sched.h | 1 +
kernel/signal.c | 11 ++++++++---
security/selinux/hooks.c | 10 +++++-----
3 files changed, 14 insertions(+), 8 deletions(-)


diff --git a/include/linux/sched.h b/include/linux/sched.h
index b4c38bc..3fa82b3 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1885,6 +1885,7 @@ extern void sched_dead(struct task_struct *p);

extern void proc_caches_init(void);
extern void flush_signals(struct task_struct *);
+extern void __flush_signals(struct task_struct *);
extern void ignore_signals(struct task_struct *);
extern void flush_signal_handlers(struct task_struct *, int force_default);
extern int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info);
diff --git a/kernel/signal.c b/kernel/signal.c
index d803473..d2dd9cf 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -249,14 +249,19 @@ void flush_sigqueue(struct sigpending *queue)
/*
* Flush all pending signals for a task.
*/
+void __flush_signals(struct task_struct *t)
+{
+ clear_tsk_thread_flag(t, TIF_SIGPENDING);
+ flush_sigqueue(&t->pending);
+ flush_sigqueue(&t->signal->shared_pending);
+}
+
void flush_signals(struct task_struct *t)
{
unsigned long flags;

spin_lock_irqsave(&t->sighand->siglock, flags);
- clear_tsk_thread_flag(t, TIF_SIGPENDING);
- flush_sigqueue(&t->pending);
- flush_sigqueue(&t->signal->shared_pending);
+ __flush_signals(t);
spin_unlock_irqrestore(&t->sighand->siglock, flags);
}

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 02c2647..76670e2 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -2378,7 +2378,6 @@ static void selinux_bprm_committed_creds(struct linux_binprm *bprm)
struct sighand_struct *psig;
u32 osid, sid;
int rc, i;
- unsigned long flags;

osid = tsec->osid;
sid = tsec->sid;
@@ -2398,11 +2397,12 @@ static void selinux_bprm_committed_creds(struct linux_binprm *bprm)
memset(&itimer, 0, sizeof itimer);
for (i = 0; i < 3; i++)
do_setitimer(i, &itimer, NULL);
- flush_signals(current);
spin_lock_irq(&current->sighand->siglock);
- flush_signal_handlers(current, 1);
- sigemptyset(&current->blocked);
- recalc_sigpending();
+ if (!(current->signal->flags & SIGNAL_GROUP_EXIT)) {
+ __flush_signals(current);
+ flush_signal_handlers(current, 1);
+ sigemptyset(&current->blocked);
+ }
spin_unlock_irq(&current->sighand->siglock);
}



\
 
 \ /
  Last update: 2009-04-29 14:45    [W:2.367 / U:0.016 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site