diff --git a/fs/smb/client/connect.c b/fs/smb/client/connect.c index 452158b4b326..a82a7c8606af 100644 --- a/fs/smb/client/connect.c +++ b/fs/smb/client/connect.c @@ -3025,6 +3025,44 @@ bind_socket(struct TCP_Server_Info *server) return rc; } +static int +smb_recv_kvec(struct TCP_Server_Info *server, struct msghdr *msg, size_t *recv) +{ + int rc = 0; + int retries = 0; + int msg_flags = server->noblocksnd ? MSG_DONTWAIT : 0; + + *recv = 0; + + while (msg_data_left(msg)) { + rc = sock_recvmsg(server->ssocket, msg, msg_flags); + if (rc == -EAGAIN) { + retries++; + if (retries >= 14 || + (!server->noblocksnd && (retries > 2))) { + cifs_server_dbg(VFS, "sends on sock %p stuck for 15 seconds\n", + server->ssocket); + return -EAGAIN; + } + msleep(1 << retries); + continue; + } + + if (rc < 0) + return rc; + + if (rc == 0) { + cifs_dbg(FYI, "Received no data (TCP RST)\n"); + return -ECONNABORTED; + } + + /* recv was at least partially successful */ + *recv += rc; + retries = 0; /* in case we get ENOSPC on the next send */ + } + return 0; +} + static int ip_rfc1001_connect(struct TCP_Server_Info *server) { @@ -3035,10 +3073,12 @@ ip_rfc1001_connect(struct TCP_Server_Info *server) * sessinit is sent but no second negprot */ struct rfc1002_session_packet req = {}; + struct rfc1002_session_packet resp = {}; struct msghdr msg = {}; struct kvec iov = {}; unsigned int len; size_t sent; + size_t recv; req.trailer.session_req.called_len = sizeof(req.trailer.session_req.called_name); @@ -3082,10 +3122,101 @@ ip_rfc1001_connect(struct TCP_Server_Info *server) /* * RFC1001 layer in at least one server requires very short break before * negprot presumably because not expecting negprot to follow so fast. - * This is a simple solution that works without complicating the code - * and causes no significant slowing down on mount for everyone else + * For example DOS SMB servers cannot process negprot if it was received + * before the server sent response for SESSION_REQUEST packet. So, wait + * for the response, read it and parse it as it can contain useful error + * information (e.g. specified server name was incorrect). For example + * even the latest Windows Server 2022 SMB1 server over port 139 send + * error if its server name was in SESSION_REQUEST packet incorrect. + * Nowadays usage of port 139 is not common, so waiting for reply here + * does not slowing down mounting of common case (over port 445). */ - usleep_range(1000, 2000); + len = offsetof(typeof(resp), trailer); + iov.iov_base = &resp; + iov.iov_len = len; + iov_iter_kvec(&msg.msg_iter, ITER_DEST, &iov, 1, len); + rc = smb_recv_kvec(server, &msg, &recv); + if (rc < 0 || recv != len) + return (rc == -EINTR || rc == -EAGAIN) ? rc : -ECONNABORTED; + + switch (resp.type) { + case RFC1002_POSITIVE_SESSION_RESPONSE: + if (be16_to_cpu(resp.length) != 0) { + cifs_dbg(VFS, "RFC 1002 positive session response but with invalid non-zero length %u\n", + be16_to_cpu(resp.length)); + return -EIO; + } + cifs_dbg(FYI, "RFC 1002 positive session response"); + break; + case RFC1002_NEGATIVE_SESSION_RESPONSE: + /* Read RFC1002 response error code and convert it to errno in rc */ + len = sizeof(resp.trailer.neg_ses_resp_error_code); + iov.iov_base = &resp.trailer.neg_ses_resp_error_code; + iov.iov_len = len; + iov_iter_kvec(&msg.msg_iter, ITER_DEST, &iov, 1, len); + if (be16_to_cpu(resp.length) == len && + smb_recv_kvec(server, &msg, &recv) == 0 && + recv == len) { + cifs_dbg(VFS, "RFC 1002 negative session response with error 0x%x\n", + resp.trailer.neg_ses_resp_error_code); + switch (resp.trailer.neg_ses_resp_error_code) { + case RFC1002_NOT_LISTENING_CALLED: + /* server does not listen for specified server name */ + fallthrough; + case RFC1002_NOT_PRESENT: + /* server name is incorrect */ + rc = -ENOENT; + cifs_dbg(VFS, "Server rejected NetBIOS servername %.15s\n", + server->server_RFC1001_name[0] ? + server->server_RFC1001_name : + DEFAULT_CIFS_CALLED_NAME); + cifs_dbg(VFS, "Specify correct NetBIOS servername in source path or with -o servern= option\n"); + break; + case RFC1002_NOT_LISTENING_CALLING: + /* client name was not accepted by server */ + rc = -EACCES; + cifs_dbg(VFS, "Server rejected NetBIOS clientname %.15s\n", + server->workstation_RFC1001_name[0] ? + server->workstation_RFC1001_name : + "LINUX_CIFS_CLNT"); + cifs_dbg(VFS, "Specify correct NetBIOS clientname with -o netbiosname= option\n"); + break; + case RFC1002_INSUFFICIENT_RESOURCE: + /* remote server resource error */ + rc = -EREMOTEIO; + break; + case RFC1002_UNSPECIFIED_ERROR: + default: + /* other/unknown error */ + rc = -EIO; + break; + } + } else { + cifs_dbg(VFS, "RFC 1002 negative session response\n"); + rc = -EIO; + } + return rc; + case RFC1002_RETARGET_SESSION_RESPONSE: + cifs_dbg(VFS, "RFC 1002 retarget session response\n"); + if (be16_to_cpu(resp.length) == sizeof(resp.trailer.retarget_resp)) { + len = sizeof(resp.trailer.retarget_resp); + iov.iov_base = &resp.trailer.retarget_resp; + iov.iov_len = len; + iov_iter_kvec(&msg.msg_iter, ITER_DEST, &iov, 1, len); + if (smb_recv_kvec(server, &msg, &recv) == 0 && recv == len) { + cifs_dbg(VFS, "Server wants to redirect connection\n"); + cifs_dbg(VFS, "Remount with options -o ip=%pI4,port=%u\n", + &resp.trailer.retarget_resp.retarget_ip_addr, + be16_to_cpu(resp.trailer.retarget_resp.port)); + } + } + cifs_dbg(VFS, "Closing connection\n"); + /* FIXME: Should we automatically redirect to new retarget_resp server? */ + return -EMULTIHOP; + default: + cifs_dbg(VFS, "RFC 1002 unknown response type 0x%x\n", resp.type); + return -EIO; + } return 0; }