smb: client: make HMAC-MD5 TFM ephemeral

The HMAC-MD5 shash TFM is used only briefly during Session Setup stage,
when computing NTLMv2 hashes.

There's no need to keep it allocated in servers' secmech the whole time,
so keep its lifetime inside setup_ntlmv2_rsp().
Signed-off-by: Enzo Matsumiya <ematsumiya@suse.de>
Signed-off-by: Steve French <stfrench@microsoft.com>

fs/smb/client/cifsencrypt.c

@@ -416,7 +416,7 @@ find_timestamp(struct cifs_ses *ses)
 }
 
 static int calc_ntlmv2_hash(struct cifs_ses *ses, char *ntlmv2_hash,
-			    const struct nls_table *nls_cp)
+			    const struct nls_table *nls_cp, struct shash_desc *hmacmd5)
 {
 	int rc = 0;
 	int len;
@@ -425,34 +425,26 @@ static int calc_ntlmv2_hash(struct cifs_ses *ses, char *ntlmv2_hash,
 	wchar_t *domain;
 	wchar_t *server;
 
-	if (!ses->server->secmech.hmacmd5) {
-		cifs_dbg(VFS, "%s: can't generate ntlmv2 hash\n", __func__);
-		return -1;
-	}
-
 	/* calculate md4 hash of password */
 	E_md4hash(ses->password, nt_hash, nls_cp);
 
-	rc = crypto_shash_setkey(ses->server->secmech.hmacmd5->tfm, nt_hash,
-				CIFS_NTHASH_SIZE);
+	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\n", __func__);
+		cifs_dbg(VFS, "%s: Could not set NT hash as a key, rc=%d\n", __func__, rc);
 		return rc;
 	}
 
-	rc = crypto_shash_init(ses->server->secmech.hmacmd5);
+	rc = crypto_shash_init(hmacmd5);
 	if (rc) {
-		cifs_dbg(VFS, "%s: Could not init hmacmd5\n", __func__);
+		cifs_dbg(VFS, "%s: Could not init HMAC-MD5, rc=%d\n", __func__, rc);
 		return rc;
 	}
 
 	/* convert ses->user_name to unicode */
 	len = ses->user_name ? strlen(ses->user_name) : 0;
 	user = kmalloc(2 + (len * 2), GFP_KERNEL);
-	if (user == NULL) {
-		rc = -ENOMEM;
-		return rc;
-	}
+	if (user == NULL)
+		return -ENOMEM;
 
 	if (len) {
 		len = cifs_strtoUTF16(user, ses->user_name, len, nls_cp);
@@ -461,11 +453,10 @@ static int calc_ntlmv2_hash(struct cifs_ses *ses, char *ntlmv2_hash,
 		*(u16 *)user = 0;
 	}
 
-	rc = crypto_shash_update(ses->server->secmech.hmacmd5,
-				(char *)user, 2 * len);
+	rc = crypto_shash_update(hmacmd5, (char *)user, 2 * len);
 	kfree(user);
 	if (rc) {
-		cifs_dbg(VFS, "%s: Could not update with user\n", __func__);
+		cifs_dbg(VFS, "%s: Could not update with user, rc=%d\n", __func__, rc);
 		return rc;
 	}
 
@@ -474,19 +465,15 @@ static int calc_ntlmv2_hash(struct cifs_ses *ses, char *ntlmv2_hash,
 		len = strlen(ses->domainName);
 
 		domain = kmalloc(2 + (len * 2), GFP_KERNEL);
-		if (domain == NULL) {
-			rc = -ENOMEM;
-			return rc;
-		}
+		if (domain == NULL)
+			return -ENOMEM;
+
 		len = cifs_strtoUTF16((__le16 *)domain, ses->domainName, len,
 				      nls_cp);
-		rc =
-		crypto_shash_update(ses->server->secmech.hmacmd5,
-					(char *)domain, 2 * len);
+		rc = crypto_shash_update(hmacmd5, (char *)domain, 2 * len);
 		kfree(domain);
 		if (rc) {
-			cifs_dbg(VFS, "%s: Could not update with domain\n",
-				 __func__);
+			cifs_dbg(VFS, "%s: Could not update with domain, rc=%d\n", __func__, rc);
 			return rc;
 		}
 	} else {
@@ -494,33 +481,27 @@ static int calc_ntlmv2_hash(struct cifs_ses *ses, char *ntlmv2_hash,
 		len = strlen(ses->ip_addr);
 
 		server = kmalloc(2 + (len * 2), GFP_KERNEL);
-		if (server == NULL) {
-			rc = -ENOMEM;
-			return rc;
-		}
-		len = cifs_strtoUTF16((__le16 *)server, ses->ip_addr, len,
-					nls_cp);
-		rc =
-		crypto_shash_update(ses->server->secmech.hmacmd5,
-					(char *)server, 2 * len);
+		if (server == NULL)
+			return -ENOMEM;
+
+		len = cifs_strtoUTF16((__le16 *)server, ses->ip_addr, len, nls_cp);
+		rc = crypto_shash_update(hmacmd5, (char *)server, 2 * len);
 		kfree(server);
 		if (rc) {
-			cifs_dbg(VFS, "%s: Could not update with server\n",
-				 __func__);
+			cifs_dbg(VFS, "%s: Could not update with server, rc=%d\n", __func__, rc);
 			return rc;
 		}
 	}
 
-	rc = crypto_shash_final(ses->server->secmech.hmacmd5,
-					ntlmv2_hash);
+	rc = crypto_shash_final(hmacmd5, ntlmv2_hash);
 	if (rc)
-		cifs_dbg(VFS, "%s: Could not generate md5 hash\n", __func__);
+		cifs_dbg(VFS, "%s: Could not generate MD5 hash, rc=%d\n", __func__, rc);
 
 	return rc;
 }
 
 static int
-CalcNTLMv2_response(const struct cifs_ses *ses, char *ntlmv2_hash)
+CalcNTLMv2_response(const struct cifs_ses *ses, char *ntlmv2_hash, struct shash_desc *hmacmd5)
 {
 	int rc;
 	struct ntlmv2_resp *ntlmv2 = (struct ntlmv2_resp *)
@@ -531,43 +512,33 @@ CalcNTLMv2_response(const struct cifs_ses *ses, char *ntlmv2_hash)
 	hash_len = ses->auth_key.len - (CIFS_SESS_KEY_SIZE +
 		offsetof(struct ntlmv2_resp, challenge.key[0]));
 
-	if (!ses->server->secmech.hmacmd5) {
-		cifs_dbg(VFS, "%s: can't generate ntlmv2 hash\n", __func__);
-		return -1;
-	}
-
-	rc = crypto_shash_setkey(ses->server->secmech.hmacmd5->tfm,
-				 ntlmv2_hash, CIFS_HMAC_MD5_HASH_SIZE);
+	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\n",
-			 __func__);
+		cifs_dbg(VFS, "%s: Could not set NTLMv2 hash as a key, rc=%d\n", __func__, rc);
 		return rc;
 	}
 
-	rc = crypto_shash_init(ses->server->secmech.hmacmd5);
+	rc = crypto_shash_init(hmacmd5);
 	if (rc) {
-		cifs_dbg(VFS, "%s: Could not init hmacmd5\n", __func__);
+		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);
+		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(ses->server->secmech.hmacmd5,
-				 ntlmv2->challenge.key, hash_len);
+		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\n", __func__);
+		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(ses->server->secmech.hmacmd5,
-				ntlmv2->ntlmv2_hash);
+	rc = crypto_shash_final(hmacmd5, ntlmv2->ntlmv2_hash);
 	if (rc)
-		cifs_dbg(VFS, "%s: Could not generate md5 hash\n", __func__);
+		cifs_dbg(VFS, "%s: Could not generate MD5 hash, rc=%d\n", __func__, rc);
 
 	return rc;
 }
@@ -575,6 +546,7 @@ CalcNTLMv2_response(const struct cifs_ses *ses, char *ntlmv2_hash)
 int
 setup_ntlmv2_rsp(struct cifs_ses *ses, const struct nls_table *nls_cp)
 {
+	struct shash_desc *hmacmd5 = NULL;
 	int rc;
 	int baselen;
 	unsigned int tilen;
@@ -640,55 +612,51 @@ setup_ntlmv2_rsp(struct cifs_ses *ses, const struct nls_table *nls_cp)
 
 	cifs_server_lock(ses->server);
 
-	rc = cifs_alloc_hash("hmac(md5)", &ses->server->secmech.hmacmd5);
+	rc = cifs_alloc_hash("hmac(md5)", &hmacmd5);
 	if (rc) {
+		cifs_dbg(VFS, "Could not allocate HMAC-MD5, rc=%d\n", rc);
 		goto unlock;
 	}
 
 	/* calculate ntlmv2_hash */
-	rc = calc_ntlmv2_hash(ses, ntlmv2_hash, nls_cp);
+	rc = calc_ntlmv2_hash(ses, ntlmv2_hash, nls_cp, hmacmd5);
 	if (rc) {
-		cifs_dbg(VFS, "Could not get v2 hash rc %d\n", 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);
+	rc = CalcNTLMv2_response(ses, ntlmv2_hash, hmacmd5);
 	if (rc) {
-		cifs_dbg(VFS, "Could not calculate CR1 rc: %d\n", rc);
+		cifs_dbg(VFS, "Could not calculate CR1, rc=%d\n", rc);
 		goto unlock;
 	}
 
 	/* now calculate the session key for NTLMv2 */
-	rc = crypto_shash_setkey(ses->server->secmech.hmacmd5->tfm,
-		ntlmv2_hash, CIFS_HMAC_MD5_HASH_SIZE);
+	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\n",
-			 __func__);
+		cifs_dbg(VFS, "%s: Could not set NTLMv2 hash as a key, rc=%d\n", __func__, rc);
 		goto unlock;
 	}
 
-	rc = crypto_shash_init(ses->server->secmech.hmacmd5);
+	rc = crypto_shash_init(hmacmd5);
 	if (rc) {
-		cifs_dbg(VFS, "%s: Could not init hmacmd5\n", __func__);
+		cifs_dbg(VFS, "%s: Could not init HMAC-MD5, rc=%d\n", __func__, rc);
 		goto unlock;
 	}
 
-	rc = crypto_shash_update(ses->server->secmech.hmacmd5,
-		ntlmv2->ntlmv2_hash,
-		CIFS_HMAC_MD5_HASH_SIZE);
+	rc = crypto_shash_update(hmacmd5, ntlmv2->ntlmv2_hash, CIFS_HMAC_MD5_HASH_SIZE);
 	if (rc) {
-		cifs_dbg(VFS, "%s: Could not update with response\n", __func__);
+		cifs_dbg(VFS, "%s: Could not update with response, rc=%d\n", __func__, rc);
 		goto unlock;
 	}
 
-	rc = crypto_shash_final(ses->server->secmech.hmacmd5,
-		ses->auth_key.response);
+	rc = crypto_shash_final(hmacmd5, ses->auth_key.response);
 	if (rc)
-		cifs_dbg(VFS, "%s: Could not generate md5 hash\n", __func__);
-
+		cifs_dbg(VFS, "%s: Could not generate MD5 hash, rc=%d\n", __func__, rc);
 unlock:
 	cifs_server_unlock(ses->server);
+	cifs_free_hash(&hmacmd5);
 setup_ntlmv2_rsp_ret:
 	kfree_sensitive(tiblob);
 
@@ -733,7 +701,6 @@ cifs_crypto_secmech_release(struct TCP_Server_Info *server)
 	cifs_free_hash(&server->secmech.hmacsha256);
 	cifs_free_hash(&server->secmech.md5);
 	cifs_free_hash(&server->secmech.sha512);
-	cifs_free_hash(&server->secmech.hmacmd5);
 
 	if (!SERVER_IS_CHAN(server)) {
 		if (server->secmech.enc) {

fs/smb/client/cifsglob.h

@@ -178,7 +178,6 @@ struct session_key {
 
 /* crypto hashing related structure/fields, not specific to a sec mech */
 struct cifs_secmech {
-	struct shash_desc *hmacmd5; /* hmacmd5 hash function, for NTLMv2/CR1 hashes */
 	struct shash_desc *md5; /* md5 hash function, for CIFS/SMB1 signatures */
 	struct shash_desc *hmacsha256; /* hmac-sha256 hash function, for SMB2 signatures */
 	struct shash_desc *sha512; /* sha512 hash function, for SMB3.1.1 preauth hash */