[Groovy][PATCH 6/7] smb3.1.1: set gcm256 when requested

[Tim Gardner]

From: Steve French <stfrench at microsoft.com>

BugLink: https://bugs.launchpad.net/bugs/1921916

update smb encryption code to set 32 byte key length and to
set gcm256 when requested on mount.

Signed-off-by: Steve French <stfrench at microsoft.com>
(cherry picked from commit 63ca5656350a9b798a20a8e5bd55be164a5abeb6)
Signed-off-by: Tim Gardner <tim.gardner at canonical.com>
---
 fs/cifs/smb2glob.h      |  1 +
 fs/cifs/smb2ops.c       | 13 ++++++++++---
 fs/cifs/smb2pdu.h       |  1 +
 fs/cifs/smb2transport.c |  8 +++++---
 4 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/fs/cifs/smb2glob.h b/fs/cifs/smb2glob.h
index cf20f0b5d836..99a1951a01ec 100644
--- a/fs/cifs/smb2glob.h
+++ b/fs/cifs/smb2glob.h
@@ -58,6 +58,7 @@
 #define SMB2_HMACSHA256_SIZE (32)
 #define SMB2_CMACAES_SIZE (16)
 #define SMB3_SIGNKEY_SIZE (16)
+#define SMB3_GCM256_CRYPTKEY_SIZE (32)
 
 /* Maximum buffer size value we can send with 1 credit */
 #define SMB2_MAX_BUFFER_SIZE 65536
diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index 37764664538b..cafff0b53dcd 100644
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -3834,7 +3834,8 @@ fill_transform_hdr(struct smb2_transform_hdr *tr_hdr, unsigned int orig_len,
 	tr_hdr->ProtocolId = SMB2_TRANSFORM_PROTO_NUM;
 	tr_hdr->OriginalMessageSize = cpu_to_le32(orig_len);
 	tr_hdr->Flags = cpu_to_le16(0x01);
-	if (cipher_type == SMB2_ENCRYPTION_AES128_GCM)
+	if ((cipher_type == SMB2_ENCRYPTION_AES128_GCM) ||
+	    (cipher_type == SMB2_ENCRYPTION_AES256_GCM))
 		get_random_bytes(&tr_hdr->Nonce, SMB3_AES_GCM_NONCE);
 	else
 		get_random_bytes(&tr_hdr->Nonce, SMB3_AES_CCM_NONCE);
@@ -3968,7 +3969,12 @@ crypt_message(struct TCP_Server_Info *server, int num_rqst,
 
 	tfm = enc ? server->secmech.ccmaesencrypt :
 						server->secmech.ccmaesdecrypt;
-	rc = crypto_aead_setkey(tfm, key, SMB3_SIGN_KEY_SIZE);
+
+	if (server->cipher_type == SMB2_ENCRYPTION_AES256_GCM)
+		rc = crypto_aead_setkey(tfm, key, SMB3_GCM256_CRYPTKEY_SIZE);
+	else
+		rc = crypto_aead_setkey(tfm, key, SMB3_SIGN_KEY_SIZE);
+
 	if (rc) {
 		cifs_server_dbg(VFS, "%s: Failed to set aead key %d\n", __func__, rc);
 		return rc;
@@ -4006,7 +4012,8 @@ crypt_message(struct TCP_Server_Info *server, int num_rqst,
 		goto free_sg;
 	}
 
-	if (server->cipher_type == SMB2_ENCRYPTION_AES128_GCM)
+	if ((server->cipher_type == SMB2_ENCRYPTION_AES128_GCM) ||
+	    (server->cipher_type == SMB2_ENCRYPTION_AES256_GCM))
 		memcpy(iv, (char *)tr_hdr->Nonce, SMB3_AES_GCM_NONCE);
 	else {
 		iv[0] = 3;
diff --git a/fs/cifs/smb2pdu.h b/fs/cifs/smb2pdu.h
index 1fa98f869888..ffb220e0c16d 100644
--- a/fs/cifs/smb2pdu.h
+++ b/fs/cifs/smb2pdu.h
@@ -333,6 +333,7 @@ struct smb2_preauth_neg_context {
 /* Encryption Algorithms Ciphers */
 #define SMB2_ENCRYPTION_AES128_CCM	cpu_to_le16(0x0001)
 #define SMB2_ENCRYPTION_AES128_GCM	cpu_to_le16(0x0002)
+/* we currently do not request AES256_CCM since presumably GCM faster */
 #define SMB2_ENCRYPTION_AES256_CCM      cpu_to_le16(0x0003)
 #define SMB2_ENCRYPTION_AES256_GCM      cpu_to_le16(0x0004)
 
diff --git a/fs/cifs/smb2transport.c b/fs/cifs/smb2transport.c
index c0348e3b1695..ebccd71cc60a 100644
--- a/fs/cifs/smb2transport.c
+++ b/fs/cifs/smb2transport.c
@@ -849,12 +849,13 @@ smb3_crypto_aead_allocate(struct TCP_Server_Info *server)
 	struct crypto_aead *tfm;
 
 	if (!server->secmech.ccmaesencrypt) {
-		if (server->cipher_type == SMB2_ENCRYPTION_AES128_GCM)
+		if ((server->cipher_type == SMB2_ENCRYPTION_AES128_GCM) ||
+		    (server->cipher_type == SMB2_ENCRYPTION_AES256_GCM))
 			tfm = crypto_alloc_aead("gcm(aes)", 0, 0);
 		else
 			tfm = crypto_alloc_aead("ccm(aes)", 0, 0);
 		if (IS_ERR(tfm)) {
-			cifs_server_dbg(VFS, "%s: Failed to alloc encrypt aead\n",
+			cifs_server_dbg(VFS, "%s: Failed alloc encrypt aead\n",
 				 __func__);
 			return PTR_ERR(tfm);
 		}
@@ -862,7 +863,8 @@ smb3_crypto_aead_allocate(struct TCP_Server_Info *server)
 	}
 
 	if (!server->secmech.ccmaesdecrypt) {
-		if (server->cipher_type == SMB2_ENCRYPTION_AES128_GCM)
+		if ((server->cipher_type == SMB2_ENCRYPTION_AES128_GCM) ||
+		    (server->cipher_type == SMB2_ENCRYPTION_AES256_GCM))
 			tfm = crypto_alloc_aead("gcm(aes)", 0, 0);
 		else
 			tfm = crypto_alloc_aead("ccm(aes)", 0, 0);
-- 
2.17.1