linux-kernel - maybe a bug in SELinux: security_context_to_sid

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Date:   Wed, 28 Feb 2018 06:47:07 +0000
From:   "Zhang, Ning A" <ning.a.zhang@...el.com>
To:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: maybe a bug in SELinux: security_context_to_sid_core

Hi,

Before SELinux is initialized, get scontext by secid by using:

security_secctx_to_secid() may return wrong numbe

eg:
security_secctx_to_secid("devnull", strlen("devnull"), &sid);

sid here will be 1

because:

in security_context_to_sid_core:

...
	if (!ss_initialized) {
		int i;

		for (i = 1; i < SECINITSID_NUM; i++) {
			if (!strcmp(initial_sid_to_string[i],
scontext)) {
				*sid = i;
				return 0;
			}
		}
		*sid = SECINITSID_KERNEL;
		return 0;
	}
...

and SECINITSID_DEVNULL equals to SECINITSID_NUM, and it will never get
right secid for "devnull".

is this by design or bug?

BR.
Ning.