From: Casey Schaufler <casey@schaufler-ca.com>
To: Oleg Nesterov <oleg@redhat.com>, Paul Moore <paul@paul-moore.com>
Cc: "chengjian (D)" <cj.chengjian@huawei.com>,
Kees Cook <keescook@chromium.org>, NeilBrown <neilb@suse.com>,
Anna Schumaker <Anna.Schumaker@netapp.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Al Viro <viro@zeniv.linux.org.uk>,
"Xiexiuqi (Xie XiuQi)" <xiexiuqi@huawei.com>,
Li Bin <huawei.libin@huawei.com>, Jason Yan <yanaijie@huawei.com>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Linux Security Module list
<linux-security-module@vger.kernel.org>,
SELinux <selinux@vger.kernel.org>,
Yang Yingliang <yangyingliang@huawei.com>,
casey@schaufler-ca.com
Subject: Re: kernel BUG at kernel/cred.c:434!
Date: Wed, 17 Apr 2019 09:42:11 -0700 [thread overview]
Message-ID: <939a45a6-fc1b-0ac3-759b-0e7c3ce3d670@schaufler-ca.com> (raw)
In-Reply-To: <20190417162723.GK32622@redhat.com>
On 4/17/2019 9:27 AM, Oleg Nesterov wrote:
> On 04/17, Paul Moore wrote:
>> On Wed, Apr 17, 2019 at 10:57 AM Oleg Nesterov <oleg@redhat.com> wrote:
>>> On 04/17, Paul Moore wrote:
>>>> I'm tempted to simply return an error in selinux_setprocattr() if
>>>> the task's credentials are not the same as its real_cred;
>>> What about other modules? I have no idea what smack_setprocattr() is,
>>> but it too does prepare_creds/commit creds.
>>>
>>> it seems that the simplest workaround should simply add the additional
>>> cred == real_cred into proc_pid_attr_write().
>> Yes, that is simple, but I worry about what other LSMs might want to
>> do. While I believe failing if the effective creds are not the same
>> as the real_creds is okay for SELinux (possibly Smack too), I worry
>> about what other LSMs may want to do. After all,
>> proc_pid_attr_write() doesn't change the the creds itself, that is
>> something the specific LSMs do.
> Yes, but if proc_pid_attr_write() is called with cred != real_cred then
> something is already wrong?
>
> In fact, I think that something is already wrong if it is not called by
> user-space directly. Too late to ask, but why is this /proc/self/attr/
> magic not implemented via syscall(s) ?
Shell scripts, for one thing. It's a straightforward and appropriate
use of the /proc interface. System calls would require additional change
to existing programs, whereas using the /proc interface allows a good
deal to be done in the containing scripts.
next prev parent reply other threads:[~2019-04-17 16:42 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <6e4428ca-3da1-a033-08f7-a51e57503989@huawei.com>
2019-04-12 15:28 ` kernel BUG at kernel/cred.c:434! Casey Schaufler
2019-04-15 13:43 ` Oleg Nesterov
2019-04-15 14:48 ` Paul Moore
2019-04-15 15:05 ` Oleg Nesterov
2019-04-15 16:20 ` Paul Moore
2019-04-16 3:40 ` Kees Cook
2019-04-16 14:46 ` chengjian (D)
2019-04-17 14:30 ` Paul Moore
2019-04-17 14:57 ` Oleg Nesterov
2019-04-17 15:39 ` Casey Schaufler
2019-04-17 15:40 ` Paul Moore
2019-04-17 16:27 ` Oleg Nesterov
2019-04-17 16:42 ` Casey Schaufler [this message]
2019-04-18 13:39 ` Stephen Smalley
2019-04-17 23:39 ` Paul Moore
2019-04-18 0:17 ` John Johansen
2019-04-18 0:24 ` Casey Schaufler
2019-04-18 2:49 ` Yang Yingliang
2019-04-19 2:04 ` Paul Moore
2019-04-19 2:34 ` Yang Yingliang
2019-04-19 13:24 ` Paul Moore
2019-04-19 14:34 ` Yang Yingliang
2019-04-19 16:13 ` Paul Moore
2019-04-20 7:38 ` Yang Yingliang
2019-04-22 19:48 ` Paul Moore
2019-04-23 4:08 ` Yang Yingliang
2019-04-23 20:18 ` Paul Moore
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