linux-kernel - [PATCH 3.16 183/212] KEYS: Reinstate EPERM for a key type name beginning with a '.'

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Message-ID: <lsq.1496331796.103128301@decadent.org.uk>
Date:   Thu, 01 Jun 2017 16:43:16 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "David Howells" <dhowells@...hat.com>,
        "Vivek Goyal" <vgoyal@...hat.com>,
        "Mimi Zohar" <zohar@...ux.vnet.ibm.com>
Subject: [PATCH 3.16 183/212] KEYS: Reinstate EPERM for a key type name
 beginning with a '.'

3.16.44-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: David Howells <dhowells@...hat.com>

commit 54e2c2c1a9d6cbb270b0999a38545fa9a69bee43 upstream.

Reinstate the generation of EPERM for a key type name beginning with a '.' in
a userspace call.  Types whose name begins with a '.' are internal only.

The test was removed by:

	commit a4e3b8d79a5c6d40f4a9703abf7fe3abcc6c3b8d
	Author: Mimi Zohar <zohar@...ux.vnet.ibm.com>
	Date:   Thu May 22 14:02:23 2014 -0400
	Subject: KEYS: special dot prefixed keyring name bug fix

I think we want to keep the restriction on type name so that userspace can't
add keys of a special internal type.

Note that removal of the test causes several of the tests in the keyutils
testsuite to fail.

Signed-off-by: David Howells <dhowells@...hat.com>
Acked-by: Vivek Goyal <vgoyal@...hat.com>
cc: Mimi Zohar <zohar@...ux.vnet.ibm.com>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 security/keys/keyctl.c | 2 ++
 1 file changed, 2 insertions(+)

--- a/security/keys/keyctl.c
+++ b/security/keys/keyctl.c
@@ -37,6 +37,8 @@ static int key_get_type_from_user(char *
 		return ret;
 	if (ret == 0 || ret >= len)
 		return -EINVAL;
+	if (type[0] == '.')
+		return -EPERM;
 	type[len - 1] = '\0';
 	return 0;
 }