integrity: support new struct public_key_signature encoding field

On systems with IMA-appraisal enabled with a policy requiring file
signatures, the "good" signature values are stored on the filesystem as
extended attributes (security.ima).  Signature verification failure
would normally be limited to just a particular file (eg. executable),
but during boot signature verification failure could result in a system
hang.

Defining and requiring a new public_key_signature field requires all
callers of asymmetric signature verification to be updated to reflect
the change.  This patch updates the integrity asymmetric_verify()
caller.

Fixes: 82f94f2 ("KEYS: Provide software public key query function [ver #2]")
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Cc: David Howells <dhowells@redhat.com>
Acked-by: Denis Kenzior <denkenz@gmail.com>
Signed-off-by: James Morris <james.morris@microsoft.com>

security/integrity/digsig_asymmetric.c

@@ -106,6 +106,7 @@ int asymmetric_verify(struct key *keyring, const char *sig,
 
 	pks.pkey_algo = "rsa";
 	pks.hash_algo = hash_algo_name[hdr->hash_algo];
+	pks.encoding = "pkcs1";
 	pks.digest = (u8 *)data;
 	pks.digest_size = datalen;
 	pks.s = hdr->sig;