cifs: Start using per session key for smb2/3 for signature generation

    Switch smb2 code to use per session session key and smb3 code to
    use per session signing key instead of per connection key to
    generate signatures.

    For that, we need to find a session to fetch the session key to
    generate signature to match for every request and response packet.

    We also forgo checking signature for a session setup response
    from the server.

Acked-by: Jeff Layton <jlayton@samba.org>
Signed-off-by: Shirish Pargaonkar <shirishpargaonkar@gmail.com>
Signed-off-by: Steve French <smfrench@gmail.com>

1 files changed, 52 insertions, 18 deletions

diff --git a/fs/cifs/smb2transport.c b/fs/cifs/smb2transport.c
index 4f2300d020c7..340abca3aa52 100644
--- a/fs/cifs/smb2transport.c
+++ b/fs/cifs/smb2transport.c
@@ -114,6 +114,23 @@ smb3_crypto_shash_allocate(struct TCP_Server_Info *server)
 	return 0;
 }
 
+static struct cifs_ses *
+smb2_find_smb_ses(struct smb2_hdr *smb2hdr, struct TCP_Server_Info *server)
+{
+	struct cifs_ses *ses;
+
+	spin_lock(&cifs_tcp_ses_lock);
+	list_for_each_entry(ses, &server->smb_ses_list, smb_ses_list) {
+		if (ses->Suid != smb2hdr->SessionId)
+			continue;
+		spin_unlock(&cifs_tcp_ses_lock);
+		return ses;
+	}
+	spin_unlock(&cifs_tcp_ses_lock);
+
+	return NULL;
+}
+
 
 int
 smb2_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
@@ -124,6 +141,13 @@ smb2_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
 	struct kvec *iov = rqst->rq_iov;
 	int n_vec = rqst->rq_nvec;
 	struct smb2_hdr *smb2_pdu = (struct smb2_hdr *)iov[0].iov_base;
+	struct cifs_ses *ses;
+
+	ses = smb2_find_smb_ses(smb2_pdu, server);
+	if (!ses) {
+		cifs_dbg(VFS, "%s: Could not find session\n", __func__);
+		return 0;
+	}
 
 	memset(smb2_signature, 0x0, SMB2_HMACSHA256_SIZE);
 	memset(smb2_pdu->Signature, 0x0, SMB2_SIGNATURE_SIZE);
@@ -135,7 +159,7 @@ smb2_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
 	}
 
 	rc = crypto_shash_setkey(server->secmech.hmacsha256,
-		server->session_key.response, SMB2_NTLMV2_SESSKEY_SIZE);
+		ses->auth_key.response, SMB2_NTLMV2_SESSKEY_SIZE);
 	if (rc) {
 		cifs_dbg(VFS, "%s: Could not update with response\n", __func__);
 		return rc;
@@ -198,8 +222,8 @@ smb2_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
 	return rc;
 }
 
-void
-generate_smb3signingkey(struct TCP_Server_Info *server)
+int
+generate_smb3signingkey(struct cifs_ses *ses)
 {
 	unsigned char zero = 0x0;
 	__u8 i[4] = {0, 0, 0, 1};
@@ -209,90 +233,99 @@ generate_smb3signingkey(struct TCP_Server_Info *server)
 	unsigned char *hashptr = prfhash;
 
 	memset(prfhash, 0x0, SMB2_HMACSHA256_SIZE);
-	memset(server->smb3signingkey, 0x0, SMB3_SIGNKEY_SIZE);
+	memset(ses->smb3signingkey, 0x0, SMB3_SIGNKEY_SIZE);
 
-	rc = smb3_crypto_shash_allocate(server);
+	rc = smb3_crypto_shash_allocate(ses->server);
 	if (rc) {
 		cifs_dbg(VFS, "%s: crypto alloc failed\n", __func__);
 		goto smb3signkey_ret;
 	}
 
-	rc = crypto_shash_setkey(server->secmech.hmacsha256,
-		server->session_key.response, SMB2_NTLMV2_SESSKEY_SIZE);
+	rc = crypto_shash_setkey(ses->server->secmech.hmacsha256,
+		ses->auth_key.response, SMB2_NTLMV2_SESSKEY_SIZE);
 	if (rc) {
 		cifs_dbg(VFS, "%s: Could not set with session key\n", __func__);
 		goto smb3signkey_ret;
 	}
 
-	rc = crypto_shash_init(&server->secmech.sdeschmacsha256->shash);
+	rc = crypto_shash_init(&ses->server->secmech.sdeschmacsha256->shash);
 	if (rc) {
 		cifs_dbg(VFS, "%s: Could not init sign hmac\n", __func__);
 		goto smb3signkey_ret;
 	}
 
-	rc = crypto_shash_update(&server->secmech.sdeschmacsha256->shash,
+	rc = crypto_shash_update(&ses->server->secmech.sdeschmacsha256->shash,
 				i, 4);
 	if (rc) {
 		cifs_dbg(VFS, "%s: Could not update with n\n", __func__);
 		goto smb3signkey_ret;
 	}
 
-	rc = crypto_shash_update(&server->secmech.sdeschmacsha256->shash,
+	rc = crypto_shash_update(&ses->server->secmech.sdeschmacsha256->shash,
 				"SMB2AESCMAC", 12);
 	if (rc) {
 		cifs_dbg(VFS, "%s: Could not update with label\n", __func__);
 		goto smb3signkey_ret;
 	}
 
-	rc = crypto_shash_update(&server->secmech.sdeschmacsha256->shash,
+	rc = crypto_shash_update(&ses->server->secmech.sdeschmacsha256->shash,
 				&zero, 1);
 	if (rc) {
 		cifs_dbg(VFS, "%s: Could not update with zero\n", __func__);
 		goto smb3signkey_ret;
 	}
 
-	rc = crypto_shash_update(&server->secmech.sdeschmacsha256->shash,
+	rc = crypto_shash_update(&ses->server->secmech.sdeschmacsha256->shash,
 				"SmbSign", 8);
 	if (rc) {
 		cifs_dbg(VFS, "%s: Could not update with context\n", __func__);
 		goto smb3signkey_ret;
 	}
 
-	rc = crypto_shash_update(&server->secmech.sdeschmacsha256->shash,
+	rc = crypto_shash_update(&ses->server->secmech.sdeschmacsha256->shash,
 				L, 4);
 	if (rc) {
 		cifs_dbg(VFS, "%s: Could not update with L\n", __func__);
 		goto smb3signkey_ret;
 	}
 
-	rc = crypto_shash_final(&server->secmech.sdeschmacsha256->shash,
+	rc = crypto_shash_final(&ses->server->secmech.sdeschmacsha256->shash,
 				hashptr);
 	if (rc) {
 		cifs_dbg(VFS, "%s: Could not generate sha256 hash\n", __func__);
 		goto smb3signkey_ret;
 	}
 
-	memcpy(server->smb3signingkey, hashptr, SMB3_SIGNKEY_SIZE);
+	memcpy(ses->smb3signingkey, hashptr, SMB3_SIGNKEY_SIZE);
 
 smb3signkey_ret:
-	return;
+	return rc;
 }
 
 int
 smb3_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
 {
-	int i, rc;
+	int i;
+	int rc = 0;
 	unsigned char smb3_signature[SMB2_CMACAES_SIZE];
 	unsigned char *sigptr = smb3_signature;
 	struct kvec *iov = rqst->rq_iov;
 	int n_vec = rqst->rq_nvec;
 	struct smb2_hdr *smb2_pdu = (struct smb2_hdr *)iov[0].iov_base;
+	struct cifs_ses *ses;
+
+	ses = smb2_find_smb_ses(smb2_pdu, server);
+	if (!ses) {
+		cifs_dbg(VFS, "%s: Could not find session\n", __func__);
+		return 0;
+	}
 
 	memset(smb3_signature, 0x0, SMB2_CMACAES_SIZE);
 	memset(smb2_pdu->Signature, 0x0, SMB2_SIGNATURE_SIZE);
 
 	rc = crypto_shash_setkey(server->secmech.cmacaes,
-		server->smb3signingkey, SMB2_CMACAES_SIZE);
+		ses->smb3signingkey, SMB2_CMACAES_SIZE);
+
 	if (rc) {
 		cifs_dbg(VFS, "%s: Could not set key for cmac aes\n", __func__);
 		return rc;
@@ -389,6 +422,7 @@ smb2_verify_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
 	struct smb2_hdr *smb2_pdu = (struct smb2_hdr *)rqst->rq_iov[0].iov_base;
 
 	if ((smb2_pdu->Command == SMB2_NEGOTIATE) ||
+	    (smb2_pdu->Command == SMB2_SESSION_SETUP) ||
 	    (smb2_pdu->Command == SMB2_OPLOCK_BREAK) ||
 	    (!server->session_estab))
 		return 0;