SMB2: Separate Kerberos authentication from SMB2_sess_setup

Add helper functions and split Kerberos authentication off
SMB2_sess_setup.

Signed-off-by: Sachin Prabhu <sprabhu@redhat.com>
Signed-off-by: Steve French <smfrench@gmail.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>

diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index d6a0456..386b512 100644 (file)
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -593,6 +593,216 @@ vneg_out:
        return -EIO;
 }
 
+struct SMB2_sess_data {
+       unsigned int xid;
+       struct cifs_ses *ses;
+       struct nls_table *nls_cp;
+       void (*func)(struct SMB2_sess_data *);
+       int result;
+       u64 previous_session;
+
+       /* we will send the SMB in three pieces:
+        * a fixed length beginning part, an optional
+        * SPNEGO blob (which can be zero length), and a
+        * last part which will include the strings
+        * and rest of bcc area. This allows us to avoid
+        * a large buffer 17K allocation
+        */
+       int buf0_type;
+       struct kvec iov[2];
+};
+
+static int
+SMB2_sess_alloc_buffer(struct SMB2_sess_data *sess_data)
+{
+       int rc;
+       struct cifs_ses *ses = sess_data->ses;
+       struct smb2_sess_setup_req *req;
+       struct TCP_Server_Info *server = ses->server;
+
+       rc = small_smb2_init(SMB2_SESSION_SETUP, NULL, (void **) &req);
+       if (rc)
+               return rc;
+
+       req->hdr.SessionId = 0; /* First session, not a reauthenticate */
+
+       /* if reconnect, we need to send previous sess id, otherwise it is 0 */
+       req->PreviousSessionId = sess_data->previous_session;
+
+       req->Flags = 0; /* MBZ */
+       /* to enable echos and oplocks */
+       req->hdr.CreditRequest = cpu_to_le16(3);
+
+       /* only one of SMB2 signing flags may be set in SMB2 request */
+       if (server->sign)
+               req->SecurityMode = SMB2_NEGOTIATE_SIGNING_REQUIRED;
+       else if (global_secflags & CIFSSEC_MAY_SIGN) /* one flag unlike MUST_ */
+               req->SecurityMode = SMB2_NEGOTIATE_SIGNING_ENABLED;
+       else
+               req->SecurityMode = 0;
+
+       req->Capabilities = 0;
+       req->Channel = 0; /* MBZ */
+
+       sess_data->iov[0].iov_base = (char *)req;
+       /* 4 for rfc1002 length field and 1 for pad */
+       sess_data->iov[0].iov_len = get_rfc1002_length(req) + 4 - 1;
+       /*
+        * This variable will be used to clear the buffer
+        * allocated above in case of any error in the calling function.
+        */
+       sess_data->buf0_type = CIFS_SMALL_BUFFER;
+
+       return 0;
+}
+
+static void
+SMB2_sess_free_buffer(struct SMB2_sess_data *sess_data)
+{
+       free_rsp_buf(sess_data->buf0_type, sess_data->iov[0].iov_base);
+       sess_data->buf0_type = CIFS_NO_BUFFER;
+}
+
+static int
+SMB2_sess_sendreceive(struct SMB2_sess_data *sess_data)
+{
+       int rc;
+       struct smb2_sess_setup_req *req = sess_data->iov[0].iov_base;
+
+       /* Testing shows that buffer offset must be at location of Buffer[0] */
+       req->SecurityBufferOffset =
+               cpu_to_le16(sizeof(struct smb2_sess_setup_req) -
+                       1 /* pad */ - 4 /* rfc1001 len */);
+       req->SecurityBufferLength = cpu_to_le16(sess_data->iov[1].iov_len);
+
+       inc_rfc1001_len(req, sess_data->iov[1].iov_len - 1 /* pad */);
+
+       /* BB add code to build os and lm fields */
+
+       rc = SendReceive2(sess_data->xid, sess_data->ses,
+                               sess_data->iov, 2,
+                               &sess_data->buf0_type,
+                               CIFS_LOG_ERROR | CIFS_NEG_OP);
+
+       return rc;
+}
+
+static int
+SMB2_sess_establish_session(struct SMB2_sess_data *sess_data)
+{
+       int rc = 0;
+       struct cifs_ses *ses = sess_data->ses;
+
+       mutex_lock(&ses->server->srv_mutex);
+       if (ses->server->sign && ses->server->ops->generate_signingkey) {
+               rc = ses->server->ops->generate_signingkey(ses);
+               kfree(ses->auth_key.response);
+               ses->auth_key.response = NULL;
+               if (rc) {
+                       cifs_dbg(FYI,
+                               "SMB3 session key generation failed\n");
+                       mutex_unlock(&ses->server->srv_mutex);
+                       goto keygen_exit;
+               }
+       }
+       if (!ses->server->session_estab) {
+               ses->server->sequence_number = 0x2;
+               ses->server->session_estab = true;
+       }
+       mutex_unlock(&ses->server->srv_mutex);
+
+       cifs_dbg(FYI, "SMB2/3 session established successfully\n");
+       spin_lock(&GlobalMid_Lock);
+       ses->status = CifsGood;
+       ses->need_reconnect = false;
+       spin_unlock(&GlobalMid_Lock);
+
+keygen_exit:
+       if (!ses->server->sign) {
+               kfree(ses->auth_key.response);
+               ses->auth_key.response = NULL;
+       }
+       return rc;
+}
+
+#ifdef CONFIG_CIFS_UPCALL
+static void
+SMB2_auth_kerberos(struct SMB2_sess_data *sess_data)
+{
+       int rc;
+       struct cifs_ses *ses = sess_data->ses;
+       struct cifs_spnego_msg *msg;
+       struct key *spnego_key = NULL;
+       struct smb2_sess_setup_rsp *rsp = NULL;
+
+       rc = SMB2_sess_alloc_buffer(sess_data);
+       if (rc)
+               goto out;
+
+       spnego_key = cifs_get_spnego_key(ses);
+       if (IS_ERR(spnego_key)) {
+               rc = PTR_ERR(spnego_key);
+               spnego_key = NULL;
+               goto out;
+       }
+
+       msg = spnego_key->payload.data[0];
+       /*
+        * check version field to make sure that cifs.upcall is
+        * sending us a response in an expected form
+        */
+       if (msg->version != CIFS_SPNEGO_UPCALL_VERSION) {
+               cifs_dbg(VFS,
+                         "bad cifs.upcall version. Expected %d got %d",
+                         CIFS_SPNEGO_UPCALL_VERSION, msg->version);
+               rc = -EKEYREJECTED;
+               goto out_put_spnego_key;
+       }
+
+       ses->auth_key.response = kmemdup(msg->data, msg->sesskey_len,
+                                        GFP_KERNEL);
+       if (!ses->auth_key.response) {
+               cifs_dbg(VFS,
+                       "Kerberos can't allocate (%u bytes) memory",
+                       msg->sesskey_len);
+               rc = -ENOMEM;
+               goto out_put_spnego_key;
+       }
+       ses->auth_key.len = msg->sesskey_len;
+
+       sess_data->iov[1].iov_base = msg->data + msg->sesskey_len;
+       sess_data->iov[1].iov_len = msg->secblob_len;
+
+       rc = SMB2_sess_sendreceive(sess_data);
+       if (rc)
+               goto out_put_spnego_key;
+
+       rsp = (struct smb2_sess_setup_rsp *)sess_data->iov[0].iov_base;
+       ses->Suid = rsp->hdr.SessionId;
+
+       ses->session_flags = le16_to_cpu(rsp->SessionFlags);
+       if (ses->session_flags & SMB2_SESSION_FLAG_ENCRYPT_DATA)
+               cifs_dbg(VFS, "SMB3 encryption not supported yet\n");
+
+       rc = SMB2_sess_establish_session(sess_data);
+out_put_spnego_key:
+       key_invalidate(spnego_key);
+       key_put(spnego_key);
+out:
+       sess_data->result = rc;
+       sess_data->func = NULL;
+       SMB2_sess_free_buffer(sess_data);
+}
+#else
+static void
+SMB2_auth_kerberos(struct SMB2_sess_data *sess_data)
+{
+       cifs_dbg(VFS, "Kerberos negotiated but upcall support disabled!\n");
+       sess_data->result = -EOPNOTSUPP;
+       sess_data->func = NULL;
+}
+#endif
+
 int
 SMB2_sess_setup(const unsigned int xid, struct cifs_ses *ses,
                const struct nls_table *nls_cp)
@@ -605,11 +815,11 @@ SMB2_sess_setup(const unsigned int xid, struct cifs_ses *ses,
        __le32 phase = NtLmNegotiate; /* NTLMSSP, if needed, is multistage */
        struct TCP_Server_Info *server = ses->server;
        u16 blob_length = 0;
-       struct key *spnego_key = NULL;
        char *security_blob = NULL;
        unsigned char *ntlmssp_blob = NULL;
        bool use_spnego = false; /* else use raw ntlmssp */
        u64 previous_session = ses->Suid;
+       struct SMB2_sess_data *sess_data;
 
        cifs_dbg(FYI, "Session Setup\n");
 
@@ -618,6 +828,20 @@ SMB2_sess_setup(const unsigned int xid, struct cifs_ses *ses,
                return -EIO;
        }
 
+       sess_data = kzalloc(sizeof(struct SMB2_sess_data), GFP_KERNEL);
+       if (!sess_data)
+               return -ENOMEM;
+       sess_data->xid = xid;
+       sess_data->ses = ses;
+       sess_data->buf0_type = CIFS_NO_BUFFER;
+       sess_data->nls_cp = (struct nls_table *) nls_cp;
+       sess_data->previous_session = ses->Suid;
+
+       if (ses->sectype == Kerberos) {
+               SMB2_auth_kerberos(sess_data);
+               goto out;
+       }
+
        /*
         * If we are here due to reconnect, free per-smb session key
         * in case signing was required.
@@ -670,47 +894,7 @@ ssetup_ntlmssp_authenticate:
        /* 4 for rfc1002 length field and 1 for pad */
        iov[0].iov_len = get_rfc1002_length(req) + 4 - 1;
 
-       if (ses->sectype == Kerberos) {
-#ifdef CONFIG_CIFS_UPCALL
-               struct cifs_spnego_msg *msg;
-
-               spnego_key = cifs_get_spnego_key(ses);
-               if (IS_ERR(spnego_key)) {
-                       rc = PTR_ERR(spnego_key);
-                       spnego_key = NULL;
-                       goto ssetup_exit;
-               }
-
-               msg = spnego_key->payload.data[0];
-               /*
-                * check version field to make sure that cifs.upcall is
-                * sending us a response in an expected form
-                */
-               if (msg->version != CIFS_SPNEGO_UPCALL_VERSION) {
-                       cifs_dbg(VFS,
-                                 "bad cifs.upcall version. Expected %d got %d",
-                                 CIFS_SPNEGO_UPCALL_VERSION, msg->version);
-                       rc = -EKEYREJECTED;
-                       goto ssetup_exit;
-               }
-               ses->auth_key.response = kmemdup(msg->data, msg->sesskey_len,
-                                                GFP_KERNEL);
-               if (!ses->auth_key.response) {
-                       cifs_dbg(VFS,
-                               "Kerberos can't allocate (%u bytes) memory",
-                               msg->sesskey_len);
-                       rc = -ENOMEM;
-                       goto ssetup_exit;
-               }
-               ses->auth_key.len = msg->sesskey_len;
-               blob_length = msg->secblob_len;
-               iov[1].iov_base = msg->data + msg->sesskey_len;
-               iov[1].iov_len = blob_length;
-#else
-               rc = -EOPNOTSUPP;
-               goto ssetup_exit;
-#endif /* CONFIG_CIFS_UPCALL */
-       } else if (phase == NtLmNegotiate) { /* if not krb5 must be ntlmssp */
+       if (phase == NtLmNegotiate) {
                ntlmssp_blob = kmalloc(sizeof(struct _NEGOTIATE_MESSAGE),
                                       GFP_KERNEL);
                if (ntlmssp_blob == NULL) {
@@ -853,12 +1037,12 @@ keygen_exit:
                kfree(ses->auth_key.response);
                ses->auth_key.response = NULL;
        }
-       if (spnego_key) {
-               key_invalidate(spnego_key);
-               key_put(spnego_key);
-       }
        kfree(ses->ntlmssp);
 
+       return rc;
+out:
+       rc = sess_data->result;
+       kfree(sess_data);
        return rc;
 }