smb: client: Use SHA-512 library for SMB3.1.1 preauth hash

Convert smb311_update_preauth_hash() to use the SHA-512 library instead
of a "sha512" crypto_shash.  This is simpler and faster.  With the
library there's no need to allocate memory, no need to handle errors,
and the SHA-512 code is accessed directly without inefficient indirect
calls and other unnecessary API overhead.

Remove the call to smb311_crypto_shash_allocate() from
smb311_update_preauth_hash(), since it appears to have been needed only
to allocate the "sha512" crypto_shash.  (It also had the side effect of
allocating the "cmac(aes)" crypto_shash, but that's also done in
generate_key() which is where the AES-CMAC key is initialized.)

For now the "sha512" crypto_shash is still being allocated elsewhere.
It will be removed in a later commit.

Reviewed-by: Stefan Metzmacher <[email protected]>
Acked-by: Ard Biesheuvel <[email protected]>
Signed-off-by: Eric Biggers <[email protected]>
Signed-off-by: Steve French <[email protected]>

Author: Eric Biggers

fs/smb/client/Kconfig

@@ -16,6 +16,7 @@ config CIFS
 	select CRYPTO_ECB
 	select CRYPTO_AES
 	select CRYPTO_LIB_ARC4
+	select CRYPTO_LIB_SHA512
 	select KEYS
 	select DNS_RESOLVER
 	select ASN1

fs/smb/client/smb2misc.c

@@ -7,6 +7,7 @@
  *              Pavel Shilovsky ([email protected]) 2012
  *
  */
+#include <crypto/sha2.h>
 #include <linux/ctype.h>
 #include "cifsglob.h"
 #include "cifsproto.h"
@@ -888,13 +889,13 @@ smb2_handle_cancelled_mid(struct mid_q_entry *mid, struct TCP_Server_Info *serve
  * @iov:	array containing the SMB request we will send to the server
  * @nvec:	number of array entries for the iov
  */
-int
+void
 smb311_update_preauth_hash(struct cifs_ses *ses, struct TCP_Server_Info *server,
 			   struct kvec *iov, int nvec)
 {
-	int i, rc;
+	int i;
 	struct smb2_hdr *hdr;
-	struct shash_desc *sha512 = NULL;
+	struct sha512_ctx sha_ctx;
 
 	hdr = (struct smb2_hdr *)iov[0].iov_base;
 	/* neg prot are always taken */
@@ -907,52 +908,22 @@ smb311_update_preauth_hash(struct cifs_ses *ses, struct TCP_Server_Info *server,
 	 * and we can test it. Preauth requires 3.1.1 for now.
 	 */
 	if (server->dialect != SMB311_PROT_ID)
-		return 0;
+		return;
 
 	if (hdr->Command != SMB2_SESSION_SETUP)
-		return 0;
+		return;
 
 	/* skip last sess setup response */
 	if ((hdr->Flags & SMB2_FLAGS_SERVER_TO_REDIR)
 	    && (hdr->Status == NT_STATUS_OK
 		|| (hdr->Status !=
 		    cpu_to_le32(NT_STATUS_MORE_PROCESSING_REQUIRED))))
-		return 0;
+		return;
 
 ok:
-	rc = smb311_crypto_shash_allocate(server);
-	if (rc)
-		return rc;
-
-	sha512 = server->secmech.sha512;
-	rc = crypto_shash_init(sha512);
-	if (rc) {
-		cifs_dbg(VFS, "%s: Could not init sha512 shash\n", __func__);
-		return rc;
-	}
-
-	rc = crypto_shash_update(sha512, ses->preauth_sha_hash,
-				 SMB2_PREAUTH_HASH_SIZE);
-	if (rc) {
-		cifs_dbg(VFS, "%s: Could not update sha512 shash\n", __func__);
-		return rc;
-	}
-
-	for (i = 0; i < nvec; i++) {
-		rc = crypto_shash_update(sha512, iov[i].iov_base, iov[i].iov_len);
-		if (rc) {
-			cifs_dbg(VFS, "%s: Could not update sha512 shash\n",
-				 __func__);
-			return rc;
-		}
-	}
-
-	rc = crypto_shash_final(sha512, ses->preauth_sha_hash);
-	if (rc) {
-		cifs_dbg(VFS, "%s: Could not finalize sha512 shash\n",
-			 __func__);
-		return rc;
-	}
-
-	return 0;
+	sha512_init(&sha_ctx);
+	sha512_update(&sha_ctx, ses->preauth_sha_hash, SMB2_PREAUTH_HASH_SIZE);
+	for (i = 0; i < nvec; i++)
+		sha512_update(&sha_ctx, iov[i].iov_base, iov[i].iov_len);
+	sha512_final(&sha_ctx, ses->preauth_sha_hash);
 }

fs/smb/client/smb2proto.h

@@ -296,9 +296,9 @@ extern void smb2_copy_fs_info_to_kstatfs(
 	 struct smb2_fs_full_size_info *pfs_inf,
 	 struct kstatfs *kst);
 extern int smb311_crypto_shash_allocate(struct TCP_Server_Info *server);
-extern int smb311_update_preauth_hash(struct cifs_ses *ses,
-				      struct TCP_Server_Info *server,
-				      struct kvec *iov, int nvec);
+extern void smb311_update_preauth_hash(struct cifs_ses *ses,
+				       struct TCP_Server_Info *server,
+				       struct kvec *iov, int nvec);
 extern int smb2_query_info_compound(const unsigned int xid,
 				    struct cifs_tcon *tcon,
 				    const char *path, u32 desired_access,