From: Oleg Nesterov <oleg@redhat.com>
To: yangshukui <yangshukui@huawei.com>
Cc: selinux@tycho.nsa.gov, linux-security-module@vger.kernel.org,
linux-kernel@vger.kernel.org,
Kefeng Wang <wangkefeng.wang@huawei.com>,
"Guohanjun (Hanjun Guo)" <guohanjun@huawei.com>,
"'Qiang Huang'" <h.huangqiang@huawei.com>,
Lizefan <lizefan@huawei.com>, "miaoxie (A)" <miaoxie@huawei.com>,
Zhangdianfang <zhangdianfang@huawei.com>,
paul@paul-moore.com, sds@tycho.nsa.gov, eparis@parisplace.org,
james.l.morris@oracle.com, ebiederm@xmission.com,
serge.hallyn@ubuntu.com
Subject: Re: SELinux lead to soft lockup when pid 1 proceess reap child
Date: Mon, 9 Jan 2017 19:12:25 +0100 [thread overview]
Message-ID: <20170109181225.GB8972@redhat.com> (raw)
In-Reply-To: <58736B2E.90201@huawei.com>
On 01/09, yangshukui wrote:
>
> --- a/security/selinux/hooks.c
> +++ b/security/selinux/hooks.c
> @@ -3596,6 +3596,9 @@ static int selinux_task_kill(struct task_struct *p,
> struct siginfo *info,
>
> static int selinux_task_wait(struct task_struct *p)
> {
> + if (pid_vnr(task_tgid(current)) == 1){
> + return 0;
this check is not really correct, it can be a sub-thread... Doesn't matter,
please see below.
> + }
> return task_has_perm(p, current, PROCESS__SIGCHLD);
> }
> It work but it permit pid 1 process to reap child without selinux check. Can
> we have a better way to handle this problem?
I never understood why security_task_wait() should deny to reap a child. But
since it can we probably want some explicit "the whole namespace goes away" check.
We could use, say, PIDNS_HASH_ADDING but I'd suggest something like a trivial change
below for now.
Eric, what do you think?
Oleg.
diff --git a/security/security.c b/security/security.c
index f825304..1330b4e 100644
--- a/security/security.c
+++ b/security/security.c
@@ -1027,6 +1027,9 @@ int security_task_kill(struct task_struct *p, struct siginfo *info,
int security_task_wait(struct task_struct *p)
{
+ /* must be the exiting child reaper */
+ if (unlikely(current->flags & PF_EXITING))
+ return 0;
return call_int_hook(task_wait, 0, p);
}
next parent reply other threads:[~2017-01-09 18:12 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <58732BCF.4090908@huawei.com>
[not found] ` <58734284.1060504@huawei.com>
[not found] ` <b7f75f65-592a-5102-0ac5-4d3aa43f0b55@huawei.com>
[not found] ` <58736B2E.90201@huawei.com>
2017-01-09 18:12 ` Oleg Nesterov [this message]
2017-01-09 18:29 ` SELinux lead to soft lockup when pid 1 proceess reap child Oleg Nesterov
2017-01-09 18:43 ` Stephen Smalley
2017-01-09 23:49 ` Paul Moore
2017-01-10 0:26 ` Casey Schaufler
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