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

[Ben Hutchings]

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

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

From: David Howells <dhowe...@redhat.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 <zo...@linux.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 <dhowe...@redhat.com>
Acked-by: Vivek Goyal <vgo...@redhat.com>
cc: Mimi Zohar <zo...@linux.vnet.ibm.com>
Signed-off-by: Ben Hutchings <b...@decadent.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;
 }