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Commit 0620fddb authored by Eric Biggers's avatar Eric Biggers Committed by James Morris
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KEYS: sanitize key structs before freeing 



While a 'struct key' itself normally does not contain sensitive
information, Documentation/security/keys.txt actually encourages this:

     "Having a payload is not required; and the payload can, in fact,
     just be a value stored in the struct key itself."

In case someone has taken this advice, or will take this advice in the
future, zero the key structure before freeing it.  We might as well, and
as a bonus this could make it a bit more difficult for an adversary to
determine which keys have recently been in use.

This is safe because the key_jar cache does not use a constructor.

Signed-off-by: default avatarEric Biggers <ebiggers@google.com>
Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
Signed-off-by: default avatarJames Morris <james.l.morris@oracle.com>
parent ee618b46

include/linux/key.h

+0 −1
Original line number Diff line number Diff line
@@ -173,7 +173,6 @@ struct key { 
#ifdef KEY_DEBUGGING

	unsigned		magic;

#define KEY_DEBUG_MAGIC		0x18273645u

#define KEY_DEBUG_MAGIC_X	0xf8e9dacbu

#endif



	unsigned long		flags;		/* status flags (change with bitops) */

security/keys/gc.c

+1 −3
Original line number Diff line number Diff line
@@ -158,9 +158,7 @@ static noinline void key_gc_unused_keys(struct list_head *keys) 


		kfree(key->description);



#ifdef KEY_DEBUGGING

		key->magic = KEY_DEBUG_MAGIC_X;

#endif

		memzero_explicit(key, sizeof(*key));

		kmem_cache_free(key_jar, key);

	}

}