FAILED: patch "[PATCH] KEYS: Only apply KEY_FLAG_KEEP to a key if a parent keyring" failed to apply to 4.4-stable tree

FAILED: patch "[PATCH] KEYS: Only apply KEY_FLAG_KEEP to a key if a parent keyring" failed to apply to 4.4-stable tree

[gregkh]

The patch below does not apply to the 4.4-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

>From eee045021fb22aeac7f5d6f2092430b530c880ee Mon Sep 17 00:00:00 2001
From: David Howells <dhowells@redhat.com>
Date: Wed, 27 Jan 2016 01:02:03 +0000
Subject: [PATCH] KEYS: Only apply KEY_FLAG_KEEP to a key if a parent keyring
 has it set

KEY_FLAG_KEEP should only be applied to a key if the keyring it is being
linked into has KEY_FLAG_KEEP set.

To this end, partially revert the following patch:

	commit 1d6d167c2efcfe9539d9cffb1a1be9c92e39c2c0
	Author: Mimi Zohar <zohar@linux.vnet.ibm.com>
	Date:   Thu Jan 7 07:46:36 2016 -0500
	KEYS: refcount bug fix

to undo the change that made it unconditional (Mimi got it right the first
time).

Without undoing this change, it becomes impossible to delete, revoke or
invalidate keys added to keyrings through __key_instantiate_and_link()
where the keyring has itself been linked to.  To test this, run the
following command sequence:

    keyctl newring foo @s
    keyctl add user a a %:foo
    keyctl unlink %user:a %:foo
    keyctl clear %:foo

With the commit mentioned above the third and fourth commands fail with
EPERM when they should succeed.

Reported-by: Stephen Gallager <sgallagh@redhat.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by:  Mimi Zohar <zohar@linux.vnet.ibm.com>
cc: Mimi Zohar <zohar@linux.vnet.ibm.com>
cc: keyrings@vger.kernel.org
cc: stable@vger.kernel.org
Signed-off-by: James Morris <james.l.morris@oracle.com>

diff --git a/security/keys/key.c b/security/keys/key.c
index 07a87311055c..09ef276c4bdc 100644
--- a/security/keys/key.c
+++ b/security/keys/key.c
@@ -430,7 +430,8 @@ static int __key_instantiate_and_link(struct key *key,
 
 			/* and link it into the destination keyring */
 			if (keyring) {
-				set_bit(KEY_FLAG_KEEP, &key->flags);
+				if (test_bit(KEY_FLAG_KEEP, &keyring->flags))
+					set_bit(KEY_FLAG_KEEP, &key->flags);
 
 				__key_link(key, _edit);
 			}

Re: FAILED: patch "[PATCH] KEYS: Only apply KEY_FLAG_KEEP to a key if a parent keyring" failed to apply to 4.4-stable tree

[Mimi Zohar]

On Tue, 2016-03-01 at 11:17 -0800, gregkh@linuxfoundation.org wrote:
> The patch below does not apply to the 4.4-stable tree.
> If someone wants it applied there, or to any other stable or longterm
> tree, then please email the backport, including the original git commit
> id to <stable@vger.kernel.org>.

Sorry for the confusion.  KEY_FLAG_KEEP is being added in 4.5.

Mimi