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>

1 files changed, 230 insertions, 46 deletions

diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index d6a045690266..386b512189b2 100644
--- 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) {
@@ -853,13 +1037,13 @@ 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;
 }
 
 int