=================================================================== RCS file: /cvsrepo/anoncvs/cvs/src/usr.bin/ssh/channels.c,v retrieving revision 1.57 retrieving revision 1.57.2.3 diff -u -r1.57 -r1.57.2.3 --- src/usr.bin/ssh/channels.c 2000/05/08 17:42:24 1.57 +++ src/usr.bin/ssh/channels.c 2000/11/08 21:30:32 1.57.2.3 @@ -1,29 +1,51 @@ /* - * - * channels.c - * * Author: Tatu Ylonen - * * Copyright (c) 1995 Tatu Ylonen , Espoo, Finland * All rights reserved - * - * Created: Fri Mar 24 16:35:24 1995 ylo - * * This file contains functions for generic socket connection forwarding. * There is also code for initiating connection forwarding for X11 connections, * arbitrary tcp/ip connections, and the authentication agent connection. * + * As far as I am concerned, the code I have written for this software + * can be used freely for any purpose. Any derived versions of this + * software must be clearly marked as such, and if the derived work is + * incompatible with the protocol description in the RFC file, it must be + * called by a name other than "ssh" or "Secure Shell". + * + * * SSH2 support added by Markus Friedl. + * Copyright (c) 1999,2000 Markus Friedl. All rights reserved. + * Copyright (c) 1999 Dug Song. All rights reserved. + * Copyright (c) 1999 Theo de Raadt. All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR + * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES + * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. + * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT + * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF + * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ #include "includes.h" -RCSID("$Id: channels.c,v 1.57 2000/05/08 17:42:24 markus Exp $"); +RCSID("$OpenBSD: channels.c,v 1.57.2.3 2000/11/08 21:30:32 jason Exp $"); #include "ssh.h" #include "packet.h" #include "xmalloc.h" #include "buffer.h" -#include "authfd.h" #include "uidswap.h" #include "readconf.h" #include "servconf.h" @@ -34,18 +56,17 @@ #include "ssh2.h" +#include +#include +#include "key.h" +#include "authfd.h" + /* Maximum number of fake X11 displays to try. */ #define MAX_DISPLAYS 1000 /* Max len of agent socket */ #define MAX_SOCKET_NAME 100 -/* default window/packet sizes for tcp/x11-fwd-channel */ -#define CHAN_TCP_WINDOW_DEFAULT (8*1024) -#define CHAN_TCP_PACKET_DEFAULT (CHAN_TCP_WINDOW_DEFAULT/2) -#define CHAN_X11_WINDOW_DEFAULT (4*1024) -#define CHAN_X11_PACKET_DEFAULT (CHAN_X11_WINDOW_DEFAULT/2) - /* * Pointer to an array containing all allocated channels. The array is * dynamically extended as needed. @@ -135,7 +156,7 @@ channel_lookup(int id) { Channel *c; - if (id < 0 && id > channels_alloc) { + if (id < 0 || id > channels_alloc) { log("channel_lookup: %d: bad id", id); return NULL; } @@ -147,30 +168,14 @@ return c; } -void -set_nonblock(int fd) -{ - int val; - val = fcntl(fd, F_GETFL, 0); - if (val < 0) { - error("fcntl(%d, F_GETFL, 0): %s", fd, strerror(errno)); - return; - } - if (val & O_NONBLOCK) - return; - debug("fd %d setting O_NONBLOCK", fd); - val |= O_NONBLOCK; - if (fcntl(fd, F_SETFL, val) == -1) - error("fcntl(%d, F_SETFL, O_NONBLOCK): %s", fd, strerror(errno)); -} - /* * Register filedescriptors for a channel, used when allocating a channel or * when the channel consumer/producer is ready, e.g. shell exec'd */ void -channel_register_fds(Channel *c, int rfd, int wfd, int efd, int extusage) +channel_register_fds(Channel *c, int rfd, int wfd, int efd, + int extusage, int nonblock) { /* Update the maximum file descriptor value. */ if (rfd > channel_max_fd_value) @@ -186,12 +191,16 @@ c->sock = (rfd == wfd) ? rfd : -1; c->efd = efd; c->extended_usage = extusage; - if (rfd != -1) - set_nonblock(rfd); - if (wfd != -1) - set_nonblock(wfd); - if (efd != -1) - set_nonblock(efd); + + /* enable nonblocking mode */ + if (nonblock) { + if (rfd != -1) + set_nonblock(rfd); + if (wfd != -1) + set_nonblock(wfd); + if (efd != -1) + set_nonblock(efd); + } } /* @@ -201,7 +210,7 @@ int channel_new(char *ctype, int type, int rfd, int wfd, int efd, - int window, int maxpack, int extusage, char *remote_name) + int window, int maxpack, int extusage, char *remote_name, int nonblock) { int i, found; Channel *c; @@ -230,7 +239,7 @@ /* There are no free slots. Take last+1 slot and expand the array. */ found = channels_alloc; channels_alloc += 10; - debug("channel: expanding %d", channels_alloc); + debug2("channel: expanding %d", channels_alloc); channels = xrealloc(channels, channels_alloc * sizeof(Channel)); for (i = found; i < channels_alloc; i++) channels[i].type = SSH_CHANNEL_FREE; @@ -241,7 +250,7 @@ buffer_init(&c->output); buffer_init(&c->extended); chan_init_iostates(c); - channel_register_fds(c, rfd, wfd, efd, extusage); + channel_register_fds(c, rfd, wfd, efd, extusage, nonblock); c->self = found; c->type = type; c->ctype = ctype; @@ -257,6 +266,7 @@ c->cb_arg = NULL; c->cb_event = 0; c->dettach_user = NULL; + c->input_filter = NULL; debug("channel %d: new [%s]", found, remote_name); return found; } @@ -264,7 +274,7 @@ int channel_allocate(int type, int sock, char *remote_name) { - return channel_new("", type, sock, sock, -1, 0, 0, 0, remote_name); + return channel_new("", type, sock, sock, -1, 0, 0, 0, remote_name, 1); } @@ -543,7 +553,7 @@ newch = channel_new("x11", SSH_CHANNEL_OPENING, newsock, newsock, -1, c->local_window_max, c->local_maxpacket, - 0, xstrdup(buf)); + 0, xstrdup(buf), 1); if (compat20) { packet_start(SSH2_MSG_CHANNEL_OPEN); packet_put_cstring("x11"); @@ -601,7 +611,7 @@ newch = channel_new("direct-tcpip", SSH_CHANNEL_OPENING, newsock, newsock, -1, c->local_window_max, c->local_maxpacket, - 0, xstrdup(buf)); + 0, xstrdup(buf), 1); if (compat20) { packet_start(SSH2_MSG_CHANNEL_OPEN); packet_put_cstring("direct-tcpip"); @@ -678,7 +688,14 @@ } return -1; } - buffer_append(&c->input, buf, len); + if(c->input_filter != NULL) { + if (c->input_filter(c, buf, len) == -1) { + debug("filter stops channel %d", c->self); + chan_read_failed(c); + } + } else { + buffer_append(&c->input, buf, len); + } } return 1; } @@ -725,7 +742,7 @@ buffer_len(&c->extended) > 0) { len = write(c->efd, buffer_ptr(&c->extended), buffer_len(&c->extended)); - debug("channel %d: written %d to efd %d", + debug2("channel %d: written %d to efd %d", c->self, len, c->efd); if (len > 0) { buffer_consume(&c->extended, len); @@ -734,7 +751,7 @@ } else if (c->extended_usage == CHAN_EXTENDED_READ && FD_ISSET(c->efd, readset)) { len = read(c->efd, buf, sizeof(buf)); - debug("channel %d: read %d from efd %d", + debug2("channel %d: read %d from efd %d", c->self, len, c->efd); if (len == 0) { debug("channel %d: closing efd %d", @@ -757,7 +774,7 @@ packet_put_int(c->remote_id); packet_put_int(c->local_consumed); packet_send(); - debug("channel %d: window %d sent adjust %d", + debug2("channel %d: window %d sent adjust %d", c->self, c->local_window, c->local_consumed); c->local_window += c->local_consumed; @@ -949,7 +966,6 @@ packet_send(); buffer_consume(&c->input, len); c->remote_window -= len; - debug("channel %d: send data len %d", c->self, len); } } else if (c->istate == CHAN_INPUT_WAIT_DRAIN) { if (compat13) @@ -987,7 +1003,7 @@ */ void -channel_input_data(int type, int plen) +channel_input_data(int type, int plen, void *ctxt) { int id; char *data; @@ -1032,7 +1048,7 @@ xfree(data); } void -channel_input_extended_data(int type, int plen) +channel_input_extended_data(int type, int plen, void *ctxt) { int id; int tcode; @@ -1065,7 +1081,7 @@ xfree(data); return; } - debug("channel %d: rcvd ext data %d", c->self, data_len); + debug2("channel %d: rcvd ext data %d", c->self, data_len); c->local_window -= data_len; buffer_append(&c->extended, data, data_len); xfree(data); @@ -1102,7 +1118,7 @@ } void -channel_input_ieof(int type, int plen) +channel_input_ieof(int type, int plen, void *ctxt) { int id; Channel *c; @@ -1117,7 +1133,7 @@ } void -channel_input_close(int type, int plen) +channel_input_close(int type, int plen, void *ctxt) { int id; Channel *c; @@ -1156,7 +1172,7 @@ /* proto version 1.5 overloads CLOSE_CONFIRMATION with OCLOSE */ void -channel_input_oclose(int type, int plen) +channel_input_oclose(int type, int plen, void *ctxt) { int id = packet_get_int(); Channel *c = channel_lookup(id); @@ -1167,7 +1183,7 @@ } void -channel_input_close_confirmation(int type, int plen) +channel_input_close_confirmation(int type, int plen, void *ctxt) { int id = packet_get_int(); Channel *c = channel_lookup(id); @@ -1183,7 +1199,7 @@ } void -channel_input_open_confirmation(int type, int plen) +channel_input_open_confirmation(int type, int plen, void *ctxt) { int id, remote_id; Channel *c; @@ -1207,9 +1223,9 @@ c->remote_maxpacket = packet_get_int(); packet_done(); if (c->cb_fn != NULL && c->cb_event == type) { - debug("callback start"); + debug2("callback start"); c->cb_fn(c->self, c->cb_arg); - debug("callback done"); + debug2("callback done"); } debug("channel %d: open confirm rwindow %d rmax %d", c->self, c->remote_window, c->remote_maxpacket); @@ -1217,7 +1233,7 @@ } void -channel_input_open_failure(int type, int plen) +channel_input_open_failure(int type, int plen, void *ctxt) { int id; Channel *c; @@ -1245,7 +1261,7 @@ } void -channel_input_channel_request(int type, int plen) +channel_input_channel_request(int type, int plen, void *ctxt) { int id; Channel *c; @@ -1258,19 +1274,19 @@ packet_disconnect("Received request for " "non-open channel %d.", id); if (c->cb_fn != NULL && c->cb_event == type) { - debug("callback start"); + debug2("callback start"); c->cb_fn(c->self, c->cb_arg); - debug("callback done"); + debug2("callback done"); } else { char *service = packet_get_string(NULL); debug("channel: %d rcvd request for %s", c->self, service); -debug("cb_fn %p cb_event %d", c->cb_fn , c->cb_event); + debug("cb_fn %p cb_event %d", c->cb_fn , c->cb_event); xfree(service); } } void -channel_input_window_adjust(int type, int plen) +channel_input_window_adjust(int type, int plen, void *ctxt) { Channel *c; int id, adjust; @@ -1289,7 +1305,7 @@ } adjust = packet_get_int(); packet_done(); - debug("channel %d: rcvd adjust %d", id, adjust); + debug2("channel %d: rcvd adjust %d", id, adjust); c->remote_window += adjust; } @@ -1499,7 +1515,7 @@ "port listener", SSH_CHANNEL_PORT_LISTENER, sock, sock, -1, CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, - 0, xstrdup("port listener")); + 0, xstrdup("port listener"), 1); strlcpy(channels[ch].path, host, sizeof(channels[ch].path)); channels[ch].host_port = host_port; channels[ch].listening_port = port; @@ -1641,7 +1657,7 @@ */ void -channel_input_port_open(int type, int plen) +channel_input_port_open(int type, int plen, void *ctxt) { u_short host_port; char *host, *originator_string; @@ -1789,7 +1805,7 @@ (void) channel_new("x11 listener", SSH_CHANNEL_X11_LISTENER, sock, sock, -1, CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT, - 0, xstrdup("X11 inet listener")); + 0, xstrdup("X11 inet listener"), 1); } /* Return a suitable value for the DISPLAY environment variable. */ @@ -1931,7 +1947,7 @@ */ void -x11_input_open(int type, int plen) +x11_input_open(int type, int plen, void *ctxt) { int remote_channel, sock = 0, newch; char *remote_host; @@ -1975,6 +1991,28 @@ } } +/* dummy protocol handler that denies SSH-1 requests (agent/x11) */ +void +deny_input_open(int type, int plen, void *ctxt) +{ + int rchan = packet_get_int(); + switch(type){ + case SSH_SMSG_AGENT_OPEN: + error("Warning: ssh server tried agent forwarding."); + break; + case SSH_SMSG_X11_OPEN: + error("Warning: ssh server tried X11 forwarding."); + break; + default: + error("deny_input_open: type %d plen %d", type, plen); + break; + } + error("Warning: this is probably a break in attempt by a malicious server."); + packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE); + packet_put_int(rchan); + packet_send(); +} + /* * Requests forwarding of X11 connections, generates fake authentication * data, and enables authentication spoofing. @@ -2074,11 +2112,11 @@ } /* - * This if called to process SSH_CMSG_AGENT_REQUEST_FORWARDING on the server. + * This is called to process SSH_CMSG_AGENT_REQUEST_FORWARDING on the server. * This starts forwarding authentication requests. */ -void +int auth_input_request_forwarding(struct passwd * pw) { int sock, newch; @@ -2096,8 +2134,16 @@ strlcpy(channel_forwarded_auth_socket_dir, "/tmp/ssh-XXXXXXXX", MAX_SOCKET_NAME); /* Create private directory for socket */ - if (mkdtemp(channel_forwarded_auth_socket_dir) == NULL) - packet_disconnect("mkdtemp: %.100s", strerror(errno)); + if (mkdtemp(channel_forwarded_auth_socket_dir) == NULL) { + packet_send_debug("Agent forwarding disabled: mkdtemp() failed: %.100s", + strerror(errno)); + restore_uid(); + xfree(channel_forwarded_auth_socket_name); + xfree(channel_forwarded_auth_socket_dir); + channel_forwarded_auth_socket_name = NULL; + channel_forwarded_auth_socket_dir = NULL; + return 0; + } snprintf(channel_forwarded_auth_socket_name, MAX_SOCKET_NAME, "%s/agent.%d", channel_forwarded_auth_socket_dir, (int) getpid()); @@ -2132,12 +2178,13 @@ xstrdup("auth socket")); strlcpy(channels[newch].path, channel_forwarded_auth_socket_name, sizeof(channels[newch].path)); + return 1; } /* This is called to process an SSH_SMSG_AGENT_OPEN message. */ void -auth_input_open_request(int type, int plen) +auth_input_open_request(int type, int plen, void *ctxt) { int remch, sock, newch; char *dummyname; @@ -2258,18 +2305,28 @@ } c->dettach_user = NULL; } +void +channel_register_filter(int id, channel_filter_fn *fn) +{ + Channel *c = channel_lookup(id); + if (c == NULL) { + log("channel_register_filter: %d: bad id", id); + return; + } + c->input_filter = fn; +} void -channel_set_fds(int id, int rfd, int wfd, int efd, int extusage) +channel_set_fds(int id, int rfd, int wfd, int efd, + int extusage, int nonblock) { Channel *c = channel_lookup(id); if (c == NULL || c->type != SSH_CHANNEL_LARVAL) fatal("channel_activate for non-larval channel %d.", id); - - channel_register_fds(c, rfd, wfd, efd, extusage); + channel_register_fds(c, rfd, wfd, efd, extusage, nonblock); c->type = SSH_CHANNEL_OPEN; /* XXX window size? */ - c->local_window = c->local_window_max = c->local_maxpacket/2; + c->local_window = c->local_window_max = c->local_maxpacket * 2; packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST); packet_put_int(c->remote_id); packet_put_int(c->local_window);