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From: Andrew Morton <akpm@linux-foundation.org>
To: Greg KH <greg@kroah.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
	Hugh Dickins <hugh@veritas.com>,
	Christoph Lameter <clameter@engr.sgi.com>,
	"David S. Miller" <davem@davemloft.net>, Andi Kleen <ak@suse.de>,
	"Luck, Tony" <tony.luck@intel.com>,
	Rik van Riel <riel@redhat.com>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	Roland McGrath <roland@redhat.com>,
	Stephen Smalley <sds@tycho.nsa.gov>
Subject: Re: incoming
Date: Fri, 4 May 2007 09:14:34 -0700
Message-ID: <20070504091434.106ad04d.akpm@linux-foundation.org> (raw)
In-Reply-To: <20070504133728.GA19460@kroah.com>

On Fri, 4 May 2007 06:37:28 -0700 Greg KH <greg@kroah.com> wrote:

> On Wed, May 02, 2007 at 03:02:52PM -0700, Andrew Morton wrote:
> > - One little security patch
> 
> Care to cc: linux-stable with it so we can do a new 2.6.21 release with
> it if needed?
> 

Ah.  The patch affects security code, but it doesn't actually address any
insecurity.  I didn't think it was needed for -stable?



From: Roland McGrath <roland@redhat.com>

wait* syscalls return -ECHILD even when an individual PID of a live child
was requested explicitly, when security_task_wait denies the operation. 
This means that something like a broken SELinux policy can produce an
unexpected failure that looks just like a bug with wait or ptrace or
something.

This patch makes do_wait return -EACCES (or other appropriate error returned
from security_task_wait() instead of -ECHILD if some children were ruled out
solely because security_task_wait failed.

[jmorris@namei.org: switch error code to EACCES]
Signed-off-by: Roland McGrath <roland@redhat.com>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Cc: Chris Wright <chrisw@sous-sol.org>
Cc: James Morris <jmorris@namei.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 kernel/exit.c |   17 +++++++++++++++--
 1 files changed, 15 insertions(+), 2 deletions(-)

diff -puN kernel/exit.c~return-eperm-not-echild-on-security_task_wait-failure kernel/exit.c
--- a/kernel/exit.c~return-eperm-not-echild-on-security_task_wait-failure
+++ a/kernel/exit.c
@@ -1033,6 +1033,8 @@ asmlinkage void sys_exit_group(int error
 
 static int eligible_child(pid_t pid, int options, struct task_struct *p)
 {
+	int err;
+
 	if (pid > 0) {
 		if (p->pid != pid)
 			return 0;
@@ -1066,8 +1068,9 @@ static int eligible_child(pid_t pid, int
 	if (delay_group_leader(p))
 		return 2;
 
-	if (security_task_wait(p))
-		return 0;
+	err = security_task_wait(p);
+	if (err)
+		return err;
 
 	return 1;
 }
@@ -1449,6 +1452,7 @@ static long do_wait(pid_t pid, int optio
 	DECLARE_WAITQUEUE(wait, current);
 	struct task_struct *tsk;
 	int flag, retval;
+	int allowed, denied;
 
 	add_wait_queue(&current->signal->wait_chldexit,&wait);
 repeat:
@@ -1457,6 +1461,7 @@ repeat:
 	 * match our criteria, even if we are not able to reap it yet.
 	 */
 	flag = 0;
+	allowed = denied = 0;
 	current->state = TASK_INTERRUPTIBLE;
 	read_lock(&tasklist_lock);
 	tsk = current;
@@ -1472,6 +1477,12 @@ repeat:
 			if (!ret)
 				continue;
 
+			if (unlikely(ret < 0)) {
+				denied = ret;
+				continue;
+			}
+			allowed = 1;
+
 			switch (p->state) {
 			case TASK_TRACED:
 				/*
@@ -1570,6 +1581,8 @@ check_continued:
 		goto repeat;
 	}
 	retval = -ECHILD;
+	if (unlikely(denied) && !allowed)
+		retval = denied;
 end:
 	current->state = TASK_RUNNING;
 	remove_wait_queue(&current->signal->wait_chldexit,&wait);
_


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  reply index

Thread overview: 49+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-05-02 22:02 incoming Andrew Morton
2007-05-02 22:31 ` incoming Benjamin Herrenschmidt
2007-05-03  7:55 ` incoming Russell King
2007-05-03  8:05   ` incoming Andrew Morton
2007-05-04 13:37 ` incoming Greg KH
2007-05-04 16:14   ` Andrew Morton [this message]
2007-05-04 17:02     ` incoming Greg KH
2007-05-04 18:57     ` incoming Roland McGrath
2007-05-04 19:24       ` incoming Greg KH
2007-05-04 19:29         ` incoming Roland McGrath
     [not found] <20190716162536.bb52b8f34a8ecf5331a86a42@linux-foundation.org>
2019-07-17  8:47 ` incoming Vlastimil Babka
2019-07-17  8:57   ` incoming Bhaskar Chowdhury
2019-07-17 16:13   ` incoming Linus Torvalds
2019-07-17 17:09     ` incoming Christian Brauner
2019-07-17 18:13     ` incoming Vlastimil Babka
2019-08-25  0:54 incoming Andrew Morton
2019-08-30 23:04 incoming Andrew Morton
2019-09-23 22:31 incoming Andrew Morton
2019-09-24  0:55 ` incoming Linus Torvalds
2019-09-24  4:31   ` incoming Andrew Morton
2019-09-24  7:48     ` incoming Michal Hocko
2019-09-24 15:34       ` incoming Linus Torvalds
2019-09-25  6:36         ` incoming Michal Hocko
2019-09-24 19:55       ` incoming Vlastimil Babka
2019-09-25 23:45 incoming Andrew Morton
2019-10-07  0:57 incoming Andrew Morton
2019-10-14 21:11 incoming Andrew Morton
2019-10-19  3:19 incoming Andrew Morton
2019-11-06  5:16 incoming Andrew Morton
2019-11-16  1:34 incoming Andrew Morton
2019-11-22  1:53 incoming Andrew Morton
2019-12-01  1:47 incoming Andrew Morton
2019-12-01  5:17 ` incoming James Bottomley
2019-12-01 21:07 ` incoming Linus Torvalds
2019-12-02  8:21   ` incoming Steven Price
2019-12-05  0:48 incoming Andrew Morton
2019-12-18  4:50 incoming Andrew Morton
2020-01-04 20:55 incoming Andrew Morton
2020-01-14  0:28 incoming Andrew Morton
2020-01-31  6:10 incoming Andrew Morton
2020-02-04  1:33 incoming Andrew Morton
2020-02-04  2:27 ` incoming Linus Torvalds
2020-02-04  2:46   ` incoming Andrew Morton
2020-02-04  3:11     ` incoming Linus Torvalds
2020-02-21  4:00 incoming Andrew Morton
2020-02-21  4:03 ` incoming Andrew Morton
2020-02-21 18:21 ` incoming Linus Torvalds
2020-02-21 18:32   ` incoming Konstantin Ryabitsev
2020-02-21 19:33   ` incoming Linus Torvalds

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