smb: client: Use HMAC-MD5 library for NTLMv2

For the HMAC-MD5 computations in NTLMv2, use the HMAC-MD5 library
instead of a "hmac(md5)" crypto_shash.  This is simpler and faster.
With the library there's no need to allocate memory, no need to handle
errors, and the HMAC-MD5 code is accessed directly without inefficient
indirect calls and other unnecessary API overhead.

To preserve the existing behavior of NTLMv2 support being disabled when
the kernel is booted with "fips=1", make setup_ntlmv2_rsp() check
fips_enabled itself.  Previously it relied on the error from
cifs_alloc_hash("hmac(md5)", &hmacmd5).

Reviewed-by: Stefan Metzmacher <metze@samba.org>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>

Author: Eric Biggers

fs/smb/client/cifsencrypt.c

@@ -425,29 +425,19 @@ static __le64 find_timestamp(struct cifs_ses *ses)
 }
 
 static int calc_ntlmv2_hash(struct cifs_ses *ses, char *ntlmv2_hash,
-			    const struct nls_table *nls_cp, struct shash_desc *hmacmd5)
+			    const struct nls_table *nls_cp)
 {
-	int rc = 0;
 	int len;
 	char nt_hash[CIFS_NTHASH_SIZE];
+	struct hmac_md5_ctx hmac_ctx;
 	__le16 *user;
 	wchar_t *domain;
 	wchar_t *server;
 
 	/* calculate md4 hash of password */
 	E_md4hash(ses->password, nt_hash, nls_cp);
 
-	rc = crypto_shash_setkey(hmacmd5->tfm, nt_hash, CIFS_NTHASH_SIZE);
-	if (rc) {
-		cifs_dbg(VFS, "%s: Could not set NT hash as a key, rc=%d\n", __func__, rc);
-		return rc;
-	}
-
-	rc = crypto_shash_init(hmacmd5);
-	if (rc) {
-		cifs_dbg(VFS, "%s: Could not init HMAC-MD5, rc=%d\n", __func__, rc);
-		return rc;
-	}
+	hmac_md5_init_usingrawkey(&hmac_ctx, nt_hash, CIFS_NTHASH_SIZE);
 
 	/* convert ses->user_name to unicode */
 	len = ses->user_name ? strlen(ses->user_name) : 0;
@@ -462,12 +452,8 @@ static int calc_ntlmv2_hash(struct cifs_ses *ses, char *ntlmv2_hash,
 		*(u16 *)user = 0;
 	}
 
-	rc = crypto_shash_update(hmacmd5, (char *)user, 2 * len);
+	hmac_md5_update(&hmac_ctx, (const u8 *)user, 2 * len);
 	kfree(user);
-	if (rc) {
-		cifs_dbg(VFS, "%s: Could not update with user, rc=%d\n", __func__, rc);
-		return rc;
-	}
 
 	/* convert ses->domainName to unicode and uppercase */
 	if (ses->domainName) {
@@ -479,12 +465,8 @@ static int calc_ntlmv2_hash(struct cifs_ses *ses, char *ntlmv2_hash,
 
 		len = cifs_strtoUTF16((__le16 *)domain, ses->domainName, len,
 				      nls_cp);
-		rc = crypto_shash_update(hmacmd5, (char *)domain, 2 * len);
+		hmac_md5_update(&hmac_ctx, (const u8 *)domain, 2 * len);
 		kfree(domain);
-		if (rc) {
-			cifs_dbg(VFS, "%s: Could not update with domain, rc=%d\n", __func__, rc);
-			return rc;
-		}
 	} else {
 		/* We use ses->ip_addr if no domain name available */
 		len = strlen(ses->ip_addr);
@@ -494,25 +476,16 @@ static int calc_ntlmv2_hash(struct cifs_ses *ses, char *ntlmv2_hash,
 			return -ENOMEM;
 
 		len = cifs_strtoUTF16((__le16 *)server, ses->ip_addr, len, nls_cp);
-		rc = crypto_shash_update(hmacmd5, (char *)server, 2 * len);
+		hmac_md5_update(&hmac_ctx, (const u8 *)server, 2 * len);
 		kfree(server);
-		if (rc) {
-			cifs_dbg(VFS, "%s: Could not update with server, rc=%d\n", __func__, rc);
-			return rc;
-		}
 	}
 
-	rc = crypto_shash_final(hmacmd5, ntlmv2_hash);
-	if (rc)
-		cifs_dbg(VFS, "%s: Could not generate MD5 hash, rc=%d\n", __func__, rc);
-
-	return rc;
+	hmac_md5_final(&hmac_ctx, ntlmv2_hash);
+	return 0;
 }
 
-static int
-CalcNTLMv2_response(const struct cifs_ses *ses, char *ntlmv2_hash, struct shash_desc *hmacmd5)
+static void CalcNTLMv2_response(const struct cifs_ses *ses, char *ntlmv2_hash)
 {
-	int rc;
 	struct ntlmv2_resp *ntlmv2 = (struct ntlmv2_resp *)
 	    (ses->auth_key.response + CIFS_SESS_KEY_SIZE);
 	unsigned int hash_len;
@@ -521,35 +494,15 @@ CalcNTLMv2_response(const struct cifs_ses *ses, char *ntlmv2_hash, struct shash_
 	hash_len = ses->auth_key.len - (CIFS_SESS_KEY_SIZE +
 		offsetof(struct ntlmv2_resp, challenge.key[0]));
 
-	rc = crypto_shash_setkey(hmacmd5->tfm, ntlmv2_hash, CIFS_HMAC_MD5_HASH_SIZE);
-	if (rc) {
-		cifs_dbg(VFS, "%s: Could not set NTLMv2 hash as a key, rc=%d\n", __func__, rc);
-		return rc;
-	}
-
-	rc = crypto_shash_init(hmacmd5);
-	if (rc) {
-		cifs_dbg(VFS, "%s: Could not init HMAC-MD5, rc=%d\n", __func__, rc);
-		return rc;
-	}
-
 	if (ses->server->negflavor == CIFS_NEGFLAVOR_EXTENDED)
 		memcpy(ntlmv2->challenge.key, ses->ntlmssp->cryptkey, CIFS_SERVER_CHALLENGE_SIZE);
 	else
 		memcpy(ntlmv2->challenge.key, ses->server->cryptkey, CIFS_SERVER_CHALLENGE_SIZE);
 
-	rc = crypto_shash_update(hmacmd5, ntlmv2->challenge.key, hash_len);
-	if (rc) {
-		cifs_dbg(VFS, "%s: Could not update with response, rc=%d\n", __func__, rc);
-		return rc;
-	}
-
-	/* Note that the MD5 digest over writes anon.challenge_key.key */
-	rc = crypto_shash_final(hmacmd5, ntlmv2->ntlmv2_hash);
-	if (rc)
-		cifs_dbg(VFS, "%s: Could not generate MD5 hash, rc=%d\n", __func__, rc);
-
-	return rc;
+	/* Note that the HMAC-MD5 value overwrites ntlmv2->challenge.key */
+	hmac_md5_usingrawkey(ntlmv2_hash, CIFS_HMAC_MD5_HASH_SIZE,
+			     ntlmv2->challenge.key, hash_len,
+			     ntlmv2->ntlmv2_hash);
 }
 
 /*
@@ -606,7 +559,6 @@ static int set_auth_key_response(struct cifs_ses *ses)
 int
 setup_ntlmv2_rsp(struct cifs_ses *ses, const struct nls_table *nls_cp)
 {
-	struct shash_desc *hmacmd5 = NULL;
 	unsigned char *tiblob = NULL; /* target info blob */
 	struct ntlmv2_resp *ntlmv2;
 	char ntlmv2_hash[16];
@@ -677,51 +629,29 @@ setup_ntlmv2_rsp(struct cifs_ses *ses, const struct nls_table *nls_cp)
 	ntlmv2->client_chal = cc;
 	ntlmv2->reserved2 = 0;
 
-	rc = cifs_alloc_hash("hmac(md5)", &hmacmd5);
-	if (rc) {
-		cifs_dbg(VFS, "Could not allocate HMAC-MD5, rc=%d\n", rc);
+	if (fips_enabled) {
+		cifs_dbg(VFS, "NTLMv2 support is disabled due to FIPS\n");
+		rc = -EOPNOTSUPP;
 		goto unlock;
 	}
 
 	/* calculate ntlmv2_hash */
-	rc = calc_ntlmv2_hash(ses, ntlmv2_hash, nls_cp, hmacmd5);
+	rc = calc_ntlmv2_hash(ses, ntlmv2_hash, nls_cp);
 	if (rc) {
 		cifs_dbg(VFS, "Could not get NTLMv2 hash, rc=%d\n", rc);
 		goto unlock;
 	}
 
 	/* calculate first part of the client response (CR1) */
-	rc = CalcNTLMv2_response(ses, ntlmv2_hash, hmacmd5);
-	if (rc) {
-		cifs_dbg(VFS, "Could not calculate CR1, rc=%d\n", rc);
-		goto unlock;
-	}
+	CalcNTLMv2_response(ses, ntlmv2_hash);
 
 	/* now calculate the session key for NTLMv2 */
-	rc = crypto_shash_setkey(hmacmd5->tfm, ntlmv2_hash, CIFS_HMAC_MD5_HASH_SIZE);
-	if (rc) {
-		cifs_dbg(VFS, "%s: Could not set NTLMv2 hash as a key, rc=%d\n", __func__, rc);
-		goto unlock;
-	}
-
-	rc = crypto_shash_init(hmacmd5);
-	if (rc) {
-		cifs_dbg(VFS, "%s: Could not init HMAC-MD5, rc=%d\n", __func__, rc);
-		goto unlock;
-	}
-
-	rc = crypto_shash_update(hmacmd5, ntlmv2->ntlmv2_hash, CIFS_HMAC_MD5_HASH_SIZE);
-	if (rc) {
-		cifs_dbg(VFS, "%s: Could not update with response, rc=%d\n", __func__, rc);
-		goto unlock;
-	}
-
-	rc = crypto_shash_final(hmacmd5, ses->auth_key.response);
-	if (rc)
-		cifs_dbg(VFS, "%s: Could not generate MD5 hash, rc=%d\n", __func__, rc);
+	hmac_md5_usingrawkey(ntlmv2_hash, CIFS_HMAC_MD5_HASH_SIZE,
+			     ntlmv2->ntlmv2_hash, CIFS_HMAC_MD5_HASH_SIZE,
+			     ses->auth_key.response);
+	rc = 0;
 unlock:
 	cifs_server_unlock(ses->server);
-	cifs_free_hash(&hmacmd5);
 setup_ntlmv2_rsp_ret:
 	kfree_sensitive(tiblob);