KEYS: encrypted: avoid encrypting/decrypting stack buffers
authorEric Biggers <ebiggers@google.com>
Thu, 8 Jun 2017 13:48:10 +0000 (14:48 +0100)
committerJames Morris <james.l.morris@oracle.com>
Fri, 9 Jun 2017 03:29:46 +0000 (13:29 +1000)
commite9ff56ac352446f55141aaef1553cee662b2e310
tree73e26cc1d669007442c1fb4c22eec12da2ac77aa
parentd636bd9f12a66ea3775c9fabbf3f8e118253467a
KEYS: encrypted: avoid encrypting/decrypting stack buffers

Since v4.9, the crypto API cannot (normally) be used to encrypt/decrypt
stack buffers because the stack may be virtually mapped.  Fix this for
the padding buffers in encrypted-keys by using ZERO_PAGE for the
encryption padding and by allocating a temporary heap buffer for the
decryption padding.

Tested with CONFIG_DEBUG_SG=y:
keyctl new_session
keyctl add user master "abcdefghijklmnop" @s
keyid=$(keyctl add encrypted desc "new user:master 25" @s)
datablob="$(keyctl pipe $keyid)"
keyctl unlink $keyid
keyid=$(keyctl add encrypted desc "load $datablob" @s)
datablob2="$(keyctl pipe $keyid)"
[ "$datablob" = "$datablob2" ] && echo "Success!"

Cc: Andy Lutomirski <luto@kernel.org>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Mimi Zohar <zohar@linux.vnet.ibm.com>
Cc: stable@vger.kernel.org # 4.9+
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: James Morris <james.l.morris@oracle.com>
security/keys/encrypted-keys/encrypted.c