X-Git-Url: http://andersk.mit.edu/gitweb/openssh.git/blobdiff_plain/489aa2e90bdb9284a1e76bb90d9e9a9cf7f121e3..ef51930f93f523426b6c383a1802061fbede93be:/serverloop.c diff --git a/serverloop.c b/serverloop.c index d9791274..58e20dfb 100644 --- a/serverloop.c +++ b/serverloop.c @@ -35,13 +35,14 @@ */ #include "includes.h" -RCSID("$OpenBSD: serverloop.c,v 1.76 2001/07/17 21:04:58 markus Exp $"); +RCSID("$OpenBSD: serverloop.c,v 1.104 2002/09/19 16:03:15 stevesk Exp $"); #include "xmalloc.h" #include "packet.h" #include "buffer.h" #include "log.h" #include "servconf.h" +#include "canohost.h" #include "sshpty.h" #include "channels.h" #include "compat.h" @@ -80,18 +81,62 @@ static int connection_in; /* Connection to client (input). */ static int connection_out; /* Connection to client (output). */ static int connection_closed = 0; /* Connection to client closed. */ static u_int buffer_high; /* "Soft" max buffer size. */ +static int client_alive_timeouts = 0; /* * This SIGCHLD kludge is used to detect when the child exits. The server * will exit after that, as soon as forwarded connections have terminated. */ -static volatile int child_terminated; /* The child has terminated. */ +static volatile sig_atomic_t child_terminated = 0; /* The child has terminated. */ /* prototypes */ static void server_init_dispatch(void); -int client_alive_timeouts = 0; +/* + * we write to this pipe if a SIGCHLD is caught in order to avoid + * the race between select() and child_terminated + */ +static int notify_pipe[2]; +static void +notify_setup(void) +{ + if (pipe(notify_pipe) < 0) { + error("pipe(notify_pipe) failed %s", strerror(errno)); + } else if ((fcntl(notify_pipe[0], F_SETFD, 1) == -1) || + (fcntl(notify_pipe[1], F_SETFD, 1) == -1)) { + error("fcntl(notify_pipe, F_SETFD) failed %s", strerror(errno)); + close(notify_pipe[0]); + close(notify_pipe[1]); + } else { + set_nonblock(notify_pipe[0]); + set_nonblock(notify_pipe[1]); + return; + } + notify_pipe[0] = -1; /* read end */ + notify_pipe[1] = -1; /* write end */ +} +static void +notify_parent(void) +{ + if (notify_pipe[1] != -1) + write(notify_pipe[1], "", 1); +} +static void +notify_prepare(fd_set *readset) +{ + if (notify_pipe[0] != -1) + FD_SET(notify_pipe[0], readset); +} +static void +notify_done(fd_set *readset) +{ + char c; + + if (notify_pipe[0] != -1 && FD_ISSET(notify_pipe[0], readset)) + while (read(notify_pipe[0], &c, 1) != -1) + debug2("notify_done: reading"); +} static void sigchld_handler(int sig) @@ -99,7 +144,10 @@ sigchld_handler(int sig) int save_errno = errno; debug("Received SIGCHLD."); child_terminated = 1; +#ifndef _UNICOS mysignal(SIGCHLD, sigchld_handler); +#endif + notify_parent(); errno = save_errno; } @@ -161,6 +209,32 @@ make_packets_from_stdout_data(void) } } +static void +client_alive_check(void) +{ + static int had_channel = 0; + int id; + + id = channel_find_open(); + if (id == -1) { + if (!had_channel) + return; + packet_disconnect("No open channels after timeout!"); + } + had_channel = 1; + + /* timeout, check to see how many we have had */ + if (++client_alive_timeouts > options.client_alive_count_max) + packet_disconnect("Timeout, your session not responding."); + + /* + * send a bogus channel request with "wantreply", + * we should get back a failure + */ + channel_request_start(id, "keepalive@openssh.com", 1); + packet_send(); +} + /* * Sleep in select() until we can do something. This will initialize the * select masks. Upon return, the masks will indicate which descriptors @@ -176,12 +250,12 @@ wait_until_can_do_something(fd_set **readsetp, fd_set **writesetp, int *maxfdp, int client_alive_scheduled = 0; /* - * if using client_alive, set the max timeout accordingly, + * if using client_alive, set the max timeout accordingly, * and indicate that this particular timeout was for client * alive by setting the client_alive_scheduled flag. * * this could be randomized somewhat to make traffic - * analysis more difficult, but we're not doing it yet. + * analysis more difficult, but we're not doing it yet. */ if (compat20 && max_time_milliseconds == 0 && options.client_alive_interval) { @@ -189,16 +263,15 @@ wait_until_can_do_something(fd_set **readsetp, fd_set **writesetp, int *maxfdp, max_time_milliseconds = options.client_alive_interval * 1000; } - /* When select fails we restart from here. */ -retry_select: - /* Allocate and update select() masks for channel descriptors. */ channel_prepare_select(readsetp, writesetp, maxfdp, nallocp, 0); if (compat20) { +#if 0 /* wrong: bad condition XXX */ if (channel_not_very_much_buffered_data()) - FD_SET(connection_in, *readsetp); +#endif + FD_SET(connection_in, *readsetp); } else { /* * Read packets from the client unless we have too much @@ -224,6 +297,7 @@ retry_select: if (fdin != -1 && buffer_len(&stdin_buffer) > 0) FD_SET(fdin, *writesetp); } + notify_prepare(*readsetp); /* * If we have buffered packet data going to the client, mark that @@ -247,42 +321,19 @@ retry_select: tv.tv_usec = 1000 * (max_time_milliseconds % 1000); tvp = &tv; } - if (tvp!=NULL) - debug3("tvp!=NULL kid %d mili %d", child_terminated, max_time_milliseconds); /* Wait for something to happen, or the timeout to expire. */ ret = select((*maxfdp)+1, *readsetp, *writesetp, NULL, tvp); if (ret == -1) { + memset(*readsetp, 0, *nallocp); + memset(*writesetp, 0, *nallocp); if (errno != EINTR) error("select: %.100s", strerror(errno)); - else - goto retry_select; - } - if (ret == 0 && client_alive_scheduled) { - /* timeout, check to see how many we have had */ - client_alive_timeouts++; + } else if (ret == 0 && client_alive_scheduled) + client_alive_check(); - if (client_alive_timeouts > options.client_alive_count_max ) { - packet_disconnect( - "Timeout, your session not responding."); - } else { - /* - * send a bogus channel request with "wantreply" - * we should get back a failure - */ - int id; - - id = channel_find_open(); - if (id != -1) { - channel_request_start(id, - "keepalive@openssh.com", 1); - packet_send(); - } else - packet_disconnect( - "No open channels after timeout!"); - } - } + notify_done(*readsetp); } /* @@ -299,14 +350,17 @@ process_input(fd_set * readset) if (FD_ISSET(connection_in, readset)) { len = read(connection_in, buf, sizeof(buf)); if (len == 0) { - verbose("Connection closed by remote host."); + verbose("Connection closed by %.100s", + get_remote_ipaddr()); connection_closed = 1; if (compat20) return; fatal_cleanup(); } else if (len < 0) { if (errno != EINTR && errno != EAGAIN) { - verbose("Read error from remote host: %.100s", strerror(errno)); + verbose("Read error from remote host " + "%.100s: %.100s", + get_remote_ipaddr(), strerror(errno)); fatal_cleanup(); } } else { @@ -349,27 +403,27 @@ static void process_output(fd_set * writeset) { struct termios tio; + u_char *data; + u_int dlen; int len; /* Write buffered data to program stdin. */ if (!compat20 && fdin != -1 && FD_ISSET(fdin, writeset)) { - len = write(fdin, buffer_ptr(&stdin_buffer), - buffer_len(&stdin_buffer)); + data = buffer_ptr(&stdin_buffer); + dlen = buffer_len(&stdin_buffer); + len = write(fdin, data, dlen); if (len < 0 && (errno == EINTR || errno == EAGAIN)) { /* do nothing */ } else if (len <= 0) { -#ifdef USE_PIPES - close(fdin); -#else if (fdin != fdout) close(fdin); else shutdown(fdin, SHUT_WR); /* We will no longer send. */ -#endif fdin = -1; } else { /* Successful write. */ - if (fdin_is_tty && tcgetattr(fdin, &tio) == 0 && + if (fdin_is_tty && dlen >= 1 && data[0] != '\r' && + tcgetattr(fdin, &tio) == 0 && !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) { /* * Simulate echo to reduce the impact of @@ -448,7 +502,7 @@ server_loop(pid_t pid, int fdin_arg, int fdout_arg, int fderr_arg) /* Initialize the SIGCHLD kludge. */ child_terminated = 0; - signal(SIGCHLD, sigchld_handler); + mysignal(SIGCHLD, sigchld_handler); /* Initialize our global variables. */ fdin = fdin_arg; @@ -468,6 +522,8 @@ server_loop(pid_t pid, int fdin_arg, int fdout_arg, int fderr_arg) connection_in = packet_get_connection_in(); connection_out = packet_get_connection_out(); + notify_setup(); + previous_stdout_buffer_bytes = 0; /* Set approximate I/O buffer size. */ @@ -512,14 +568,10 @@ server_loop(pid_t pid, int fdin_arg, int fdout_arg, int fderr_arg) * input data, cause a real eof by closing fdin. */ if (stdin_eof && fdin != -1 && buffer_len(&stdin_buffer) == 0) { -#ifdef USE_PIPES - close(fdin); -#else if (fdin != fdout) close(fdin); else shutdown(fdin, SHUT_WR); /* We will no longer send. */ -#endif fdin = -1; } /* Make packets from buffered stderr data to send to the client. */ @@ -573,6 +625,7 @@ server_loop(pid_t pid, int fdin_arg, int fdout_arg, int fderr_arg) max_fd = MAX(max_fd, fdin); max_fd = MAX(max_fd, fdout); max_fd = MAX(max_fd, fderr); + max_fd = MAX(max_fd, notify_pipe[0]); /* Sleep in select() until we can do something. */ wait_until_can_do_something(&readset, &writeset, &max_fd, @@ -598,7 +651,7 @@ server_loop(pid_t pid, int fdin_arg, int fdout_arg, int fderr_arg) drain_output(); debug("End of interactive session; stdin %ld, stdout (read %ld, sent %ld), stderr %ld bytes.", - stdin_bytes, fdout_bytes, stdout_bytes, stderr_bytes); + stdin_bytes, fdout_bytes, stdout_bytes, stderr_bytes); /* Free and clear the buffers. */ buffer_free(&stdin_buffer); @@ -621,14 +674,14 @@ server_loop(pid_t pid, int fdin_arg, int fdout_arg, int fderr_arg) channel_free_all(); /* We no longer want our SIGCHLD handler to be called. */ - signal(SIGCHLD, SIG_DFL); + mysignal(SIGCHLD, SIG_DFL); - wait_pid = waitpid(-1, &wait_status, child_terminated ? WNOHANG : 0); - if (wait_pid == -1) - packet_disconnect("wait: %.100s", strerror(errno)); - else if (wait_pid != pid) - error("Strange, wait returned pid %d, expected %d", - wait_pid, pid); + while ((wait_pid = waitpid(-1, &wait_status, 0)) < 0) + if (errno != EINTR) + packet_disconnect("wait: %.100s", strerror(errno)); + if (wait_pid != pid) + error("Strange, wait returned pid %ld, expected %ld", + (long)wait_pid, (long)pid); /* Check if it exited normally. */ if (WIFEXITED(wait_status)) { @@ -647,8 +700,7 @@ server_loop(pid_t pid, int fdin_arg, int fdout_arg, int fderr_arg) * the exit status. */ do { - int plen; - type = packet_read(&plen); + type = packet_read(); } while (type != SSH_CMSG_EXIT_CONFIRMATION); @@ -665,12 +717,32 @@ server_loop(pid_t pid, int fdin_arg, int fdout_arg, int fderr_arg) /* NOTREACHED */ } +static void +collect_children(void) +{ + pid_t pid; + sigset_t oset, nset; + int status; + + /* block SIGCHLD while we check for dead children */ + sigemptyset(&nset); + sigaddset(&nset, SIGCHLD); + sigprocmask(SIG_BLOCK, &nset, &oset); + if (child_terminated) { + while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || + (pid < 0 && errno == EINTR)) + if (pid > 0) + session_close_by_pid(pid, status); + child_terminated = 0; + } + sigprocmask(SIG_SETMASK, &oset, NULL); +} + void server_loop2(Authctxt *authctxt) { fd_set *readset = NULL, *writeset = NULL; - int rekeying = 0, max_fd, status, nalloc = 0; - pid_t pid; + int rekeying = 0, max_fd, nalloc = 0; debug("Entering interactive session for SSH2."); @@ -679,7 +751,11 @@ server_loop2(Authctxt *authctxt) connection_in = packet_get_connection_in(); connection_out = packet_get_connection_out(); + notify_setup(); + max_fd = MAX(connection_in, connection_out); + max_fd = MAX(max_fd, notify_pipe[0]); + xxx_authctxt = authctxt; server_init_dispatch(); @@ -693,11 +769,8 @@ server_loop2(Authctxt *authctxt) channel_output_poll(); wait_until_can_do_something(&readset, &writeset, &max_fd, &nalloc, 0); - if (child_terminated) { - while ((pid = waitpid(-1, &status, WNOHANG)) > 0) - session_close_by_pid(pid, status); - child_terminated = 0; - } + + collect_children(); if (!rekeying) channel_after_select(readset, writeset); process_input(readset); @@ -705,49 +778,35 @@ server_loop2(Authctxt *authctxt) break; process_output(writeset); } + collect_children(); + if (readset) xfree(readset); if (writeset) xfree(writeset); - signal(SIGCHLD, SIG_DFL); - - while ((pid = waitpid(-1, &status, WNOHANG)) > 0) - session_close_by_pid(pid, status); - /* - * there is a race between channel_free_all() killing children and - * children dying before kill() - */ - channel_detach_all(); - channel_stop_listening(); - - while (session_have_children()) { - pid = waitpid(-1, &status, 0); - if (pid > 0) - session_close_by_pid(pid, status); - else { - error("waitpid returned %d: %s", pid, strerror(errno)); - break; - } - } + /* free all channels, no more reads and writes */ channel_free_all(); + + /* free remaining sessions, e.g. remove wtmp entries */ + session_destroy_all(NULL); } static void -server_input_channel_failure(int type, int plen, void *ctxt) +server_input_channel_failure(int type, u_int32_t seq, void *ctxt) { debug("Got CHANNEL_FAILURE for keepalive"); - /* + /* * reset timeout, since we got a sane answer from the client. * even if this was generated by something other than * the bogus CHANNEL_REQUEST we send for keepalives. */ - client_alive_timeouts = 0; + client_alive_timeouts = 0; } static void -server_input_stdin_data(int type, int plen, void *ctxt) +server_input_stdin_data(int type, u_int32_t seq, void *ctxt) { char *data; u_int data_len; @@ -757,14 +816,14 @@ server_input_stdin_data(int type, int plen, void *ctxt) if (fdin == -1) return; data = packet_get_string(&data_len); - packet_integrity_check(plen, (4 + data_len), type); + packet_check_eom(); buffer_append(&stdin_buffer, data, data_len); memset(data, 0, data_len); xfree(data); } static void -server_input_eof(int type, int plen, void *ctxt) +server_input_eof(int type, u_int32_t seq, void *ctxt) { /* * Eof from the client. The stdin descriptor to the @@ -772,12 +831,12 @@ server_input_eof(int type, int plen, void *ctxt) * drained. */ debug("EOF received for stdin."); - packet_integrity_check(plen, 0, type); + packet_check_eom(); stdin_eof = 1; } static void -server_input_window_size(int type, int plen, void *ctxt) +server_input_window_size(int type, u_int32_t seq, void *ctxt) { int row = packet_get_int(); int col = packet_get_int(); @@ -785,7 +844,7 @@ server_input_window_size(int type, int plen, void *ctxt) int ypixel = packet_get_int(); debug("Window change received."); - packet_integrity_check(plen, 4 * 4, type); + packet_check_eom(); if (fdin != -1) pty_change_window_size(fdin, row, col, xpixel, ypixel); } @@ -802,7 +861,7 @@ server_request_direct_tcpip(char *ctype) target_port = packet_get_int(); originator = packet_get_string(NULL); originator_port = packet_get_int(); - packet_done(); + packet_check_eom(); debug("server_request_direct_tcpip: originator %s port %d, target %s port %d", originator, originator_port, target, target_port); @@ -816,10 +875,6 @@ server_request_direct_tcpip(char *ctype) c = channel_new(ctype, SSH_CHANNEL_CONNECTING, sock, sock, -1, CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, xstrdup("direct-tcpip"), 1); - if (c == NULL) { - error("server_request_direct_tcpip: channel_new failed"); - close(sock); - } return c; } @@ -829,7 +884,7 @@ server_request_session(char *ctype) Channel *c; debug("input_session_request"); - packet_done(); + packet_check_eom(); /* * A server session has no fd to read or write until a * CHANNEL_REQUEST for a shell is made, so we set the type to @@ -839,30 +894,22 @@ server_request_session(char *ctype) c = channel_new(ctype, SSH_CHANNEL_LARVAL, -1, -1, -1, /*window size*/0, CHAN_SES_PACKET_DEFAULT, 0, xstrdup("server-session"), 1); - if (c == NULL) { - error("server_request_session: channel_new failed"); - return NULL; - } if (session_open(xxx_authctxt, c->self) != 1) { debug("session open failed, free channel %d", c->self); channel_free(c); return NULL; } - channel_register_callback(c->self, SSH2_MSG_CHANNEL_REQUEST, - session_input_channel_req, (void *)0); channel_register_cleanup(c->self, session_close_by_channel); return c; } static void -server_input_channel_open(int type, int plen, void *ctxt) +server_input_channel_open(int type, u_int32_t seq, void *ctxt) { Channel *c = NULL; char *ctype; - u_int len; int rchan; - int rmaxpack; - int rwindow; + u_int rmaxpack, rwindow, len; ctype = packet_get_string(&len); rchan = packet_get_int(); @@ -905,7 +952,7 @@ server_input_channel_open(int type, int plen, void *ctxt) } static void -server_input_global_request(int type, int plen, void *ctxt) +server_input_global_request(int type, u_int32_t seq, void *ctxt) { char *rtype; int want_reply; @@ -931,17 +978,17 @@ server_input_global_request(int type, int plen, void *ctxt) /* check permissions */ if (!options.allow_tcp_forwarding || - no_port_forwarding_flag || - (listen_port < IPPORT_RESERVED && pw->pw_uid != 0)) { + no_port_forwarding_flag +#ifndef NO_IPPORT_RESERVED_CONCEPT + || (listen_port < IPPORT_RESERVED && pw->pw_uid != 0) +#endif + ) { success = 0; packet_send_debug("Server has disabled port forwarding."); } else { /* Start listening on the port */ - success = channel_request_forwarding( - listen_address, listen_port, - /*unspec host_to_connect*/ "", - /*unspec port_to_connect*/ 0, - options.gateway_ports, /*remote*/ 1); + success = channel_setup_remote_fwd_listener( + listen_address, listen_port, options.gateway_ports); } xfree(listen_address); } @@ -953,6 +1000,33 @@ server_input_global_request(int type, int plen, void *ctxt) } xfree(rtype); } +static void +server_input_channel_req(int type, u_int32_t seq, void *ctxt) +{ + Channel *c; + int id, reply, success = 0; + char *rtype; + + id = packet_get_int(); + rtype = packet_get_string(NULL); + reply = packet_get_char(); + + debug("server_input_channel_req: channel %d request %s reply %d", + id, rtype, reply); + + if ((c = channel_lookup(id)) == NULL) + packet_disconnect("server_input_channel_req: " + "unknown channel %d", id); + if (c->type == SSH_CHANNEL_LARVAL || c->type == SSH_CHANNEL_OPEN) + success = session_input_channel_req(c, rtype); + if (reply) { + packet_start(success ? + SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE); + packet_put_int(c->remote_id); + packet_send(); + } + xfree(rtype); +} static void server_init_dispatch_20(void) @@ -966,7 +1040,7 @@ server_init_dispatch_20(void) dispatch_set(SSH2_MSG_CHANNEL_OPEN, &server_input_channel_open); dispatch_set(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); dispatch_set(SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); - dispatch_set(SSH2_MSG_CHANNEL_REQUEST, &channel_input_channel_request); + dispatch_set(SSH2_MSG_CHANNEL_REQUEST, &server_input_channel_req); dispatch_set(SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust); dispatch_set(SSH2_MSG_GLOBAL_REQUEST, &server_input_global_request); /* client_alive */