X-Git-Url: http://andersk.mit.edu/gitweb/openssh.git/blobdiff_plain/2b8dc5e36b8af5e806f0ce4cfc04d34743157f47..HEAD:/sshconnect.c diff --git a/sshconnect.c b/sshconnect.c index e855f192..63c4650f 100644 --- a/sshconnect.c +++ b/sshconnect.c @@ -1,4 +1,4 @@ -/* $OpenBSD: sshconnect.c,v 1.182 2006/05/17 12:43:34 markus Exp $ */ +/* $OpenBSD: sshconnect.c,v 1.218 2010/01/13 00:19:04 dtucker Exp $ */ /* * Author: Tatu Ylonen * Copyright (c) 1995 Tatu Ylonen , Espoo, Finland @@ -18,14 +18,32 @@ #include #include #include +#include +#ifdef HAVE_SYS_TIME_H +# include +#endif + +#include +#include #include +#include +#include +#include #ifdef HAVE_PATHS_H #include #endif +#include +#include +#include +#include +#include +#include -#include "ssh.h" #include "xmalloc.h" +#include "key.h" +#include "hostfile.h" +#include "ssh.h" #include "rsa.h" #include "buffer.h" #include "packet.h" @@ -39,6 +57,8 @@ #include "atomicio.h" #include "misc.h" #include "dns.h" +#include "roaming.h" +#include "version.h" char *client_version_string = NULL; char *server_version_string = NULL; @@ -52,10 +72,6 @@ extern uid_t original_real_uid; extern uid_t original_effective_uid; extern pid_t proxy_command_pid; -#ifndef INET6_ADDRSTRLEN /* for non IPv6 machines */ -#define INET6_ADDRSTRLEN 46 -#endif - static int show_other_keys(const char *, Key *); static void warn_changed_key(Key *); @@ -68,7 +84,10 @@ ssh_proxy_connect(const char *host, u_short port, const char *proxy_command) char *command_string, *tmp; int pin[2], pout[2]; pid_t pid; - char strport[NI_MAXSERV]; + char *shell, strport[NI_MAXSERV]; + + if ((shell = getenv("SHELL")) == NULL) + shell = _PATH_BSHELL; /* Convert the port number into a string. */ snprintf(strport, sizeof strport, "%hu", port); @@ -97,8 +116,7 @@ ssh_proxy_connect(const char *host, u_short port, const char *proxy_command) char *argv[10]; /* Child. Permanently give up superuser privileges. */ - seteuid(original_real_uid); - setuid(original_real_uid); + permanently_drop_suid(original_real_uid); /* Redirect stdin and stdout. */ close(pin[1]); @@ -115,7 +133,7 @@ ssh_proxy_connect(const char *host, u_short port, const char *proxy_command) /* Stderr is left as it is so that error messages get printed on the user's terminal. */ - argv[0] = _PATH_BSHELL; + argv[0] = shell; argv[1] = "-c"; argv[2] = command_string; argv[3] = NULL; @@ -141,6 +159,8 @@ ssh_proxy_connect(const char *host, u_short port, const char *proxy_command) /* Set the connection file descriptors. */ packet_set_connection(pout[0], pin[1]); + packet_set_timeout(options.server_alive_interval, + options.server_alive_count_max); /* Indicate OK return */ return 0; @@ -172,8 +192,11 @@ ssh_create_socket(int privileged, struct addrinfo *ai) return sock; } sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol); - if (sock < 0) + if (sock < 0) { error("socket: %.100s", strerror(errno)); + return -1; + } + fcntl(sock, F_SETFD, FD_CLOEXEC); /* Bind the socket to an alternative local IP address */ if (options.bind_address == NULL) @@ -184,10 +207,10 @@ ssh_create_socket(int privileged, struct addrinfo *ai) hints.ai_socktype = ai->ai_socktype; hints.ai_protocol = ai->ai_protocol; hints.ai_flags = AI_PASSIVE; - gaierr = getaddrinfo(options.bind_address, "0", &hints, &res); + gaierr = getaddrinfo(options.bind_address, NULL, &hints, &res); if (gaierr) { error("getaddrinfo: %s: %s", options.bind_address, - gai_strerror(gaierr)); + ssh_gai_strerror(gaierr)); close(sock); return -1; } @@ -203,30 +226,36 @@ ssh_create_socket(int privileged, struct addrinfo *ai) static int timeout_connect(int sockfd, const struct sockaddr *serv_addr, - socklen_t addrlen, int timeout) + socklen_t addrlen, int *timeoutp) { fd_set *fdset; - struct timeval tv; + struct timeval tv, t_start; socklen_t optlen; int optval, rc, result = -1; - if (timeout <= 0) - return (connect(sockfd, serv_addr, addrlen)); + gettimeofday(&t_start, NULL); + + if (*timeoutp <= 0) { + result = connect(sockfd, serv_addr, addrlen); + goto done; + } set_nonblock(sockfd); rc = connect(sockfd, serv_addr, addrlen); if (rc == 0) { unset_nonblock(sockfd); - return (0); + result = 0; + goto done; + } + if (errno != EINPROGRESS) { + result = -1; + goto done; } - if (errno != EINPROGRESS) - return (-1); fdset = (fd_set *)xcalloc(howmany(sockfd + 1, NFDBITS), sizeof(fd_mask)); FD_SET(sockfd, fdset); - tv.tv_sec = timeout; - tv.tv_usec = 0; + ms_to_timeval(&tv, *timeoutp); for (;;) { rc = select(sockfd + 1, NULL, fdset, NULL, &tv); @@ -265,6 +294,16 @@ timeout_connect(int sockfd, const struct sockaddr *serv_addr, } xfree(fdset); + + done: + if (result == 0 && *timeoutp > 0) { + ms_subtract_diff(&t_start, timeoutp); + if (*timeoutp <= 0) { + errno = ETIMEDOUT; + result = -1; + } + } + return (result); } @@ -281,8 +320,8 @@ timeout_connect(int sockfd, const struct sockaddr *serv_addr, */ int ssh_connect(const char *host, struct sockaddr_storage * hostaddr, - u_short port, int family, int connection_attempts, - int needpriv, const char *proxy_command) + u_short port, int family, int connection_attempts, int *timeout_ms, + int want_keepalive, int needpriv, const char *proxy_command) { int gaierr; int on = 1; @@ -303,13 +342,15 @@ ssh_connect(const char *host, struct sockaddr_storage * hostaddr, hints.ai_socktype = SOCK_STREAM; snprintf(strport, sizeof strport, "%u", port); if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0) - fatal("%s: %.100s: %s", __progname, host, - gai_strerror(gaierr)); + fatal("%s: Could not resolve hostname %.100s: %s", __progname, + host, ssh_gai_strerror(gaierr)); for (attempt = 0; attempt < connection_attempts; attempt++) { - if (attempt > 0) + if (attempt > 0) { + /* Sleep a moment before retrying. */ + sleep(1); debug("Trying again..."); - + } /* * Loop through addresses for this host, and try each one in * sequence until the connection succeeds. @@ -333,7 +374,7 @@ ssh_connect(const char *host, struct sockaddr_storage * hostaddr, continue; if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen, - options.connection_timeout) >= 0) { + timeout_ms) >= 0) { /* Successful connection. */ memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen); break; @@ -346,9 +387,6 @@ ssh_connect(const char *host, struct sockaddr_storage * hostaddr, } if (sock != -1) break; /* Successful connection. */ - - /* Sleep a moment before retrying. */ - sleep(1); } freeaddrinfo(aitop); @@ -363,13 +401,15 @@ ssh_connect(const char *host, struct sockaddr_storage * hostaddr, debug("Connection established."); /* Set SO_KEEPALIVE if requested. */ - if (options.tcp_keep_alive && + if (want_keepalive && setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on, sizeof(on)) < 0) error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); /* Set the connection. */ packet_set_connection(sock, sock); + packet_set_timeout(options.server_alive_interval, + options.server_alive_count_max); return 0; } @@ -378,25 +418,53 @@ ssh_connect(const char *host, struct sockaddr_storage * hostaddr, * Waits for the server identification string, and sends our own * identification string. */ -static void -ssh_exchange_identification(void) +void +ssh_exchange_identification(int timeout_ms) { char buf[256], remote_version[256]; /* must be same size! */ int remote_major, remote_minor, mismatch; int connection_in = packet_get_connection_in(); int connection_out = packet_get_connection_out(); int minor1 = PROTOCOL_MINOR_1; - u_int i; + u_int i, n; + size_t len; + int fdsetsz, remaining, rc; + struct timeval t_start, t_remaining; + fd_set *fdset; + + fdsetsz = howmany(connection_in + 1, NFDBITS) * sizeof(fd_mask); + fdset = xcalloc(1, fdsetsz); /* Read other side's version identification. */ - for (;;) { + remaining = timeout_ms; + for (n = 0;;) { for (i = 0; i < sizeof(buf) - 1; i++) { - size_t len = atomicio(read, connection_in, &buf[i], 1); + if (timeout_ms > 0) { + gettimeofday(&t_start, NULL); + ms_to_timeval(&t_remaining, remaining); + FD_SET(connection_in, fdset); + rc = select(connection_in + 1, fdset, NULL, + fdset, &t_remaining); + ms_subtract_diff(&t_start, &remaining); + if (rc == 0 || remaining <= 0) + fatal("Connection timed out during " + "banner exchange"); + if (rc == -1) { + if (errno == EINTR) + continue; + fatal("ssh_exchange_identification: " + "select: %s", strerror(errno)); + } + } + + len = roaming_atomicio(read, connection_in, &buf[i], 1); if (len != 1 && errno == EPIPE) - fatal("ssh_exchange_identification: Connection closed by remote host"); + fatal("ssh_exchange_identification: " + "Connection closed by remote host"); else if (len != 1) - fatal("ssh_exchange_identification: read: %.100s", strerror(errno)); + fatal("ssh_exchange_identification: " + "read: %.100s", strerror(errno)); if (buf[i] == '\r') { buf[i] = '\n'; buf[i + 1] = 0; @@ -406,6 +474,9 @@ ssh_exchange_identification(void) buf[i + 1] = 0; break; } + if (++n > 65536) + fatal("ssh_exchange_identification: " + "No banner received"); } buf[sizeof(buf) - 1] = 0; if (strncmp(buf, "SSH-", 4) == 0) @@ -413,6 +484,7 @@ ssh_exchange_identification(void) debug("ssh_exchange_identification: %s", buf); } server_version_string = xstrdup(buf); + xfree(fdset); /* * Check that the versions match. In future this might accept @@ -466,11 +538,12 @@ ssh_exchange_identification(void) (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1, remote_major); /* Send our own protocol version identification. */ - snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", + snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s%s", compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1, compat20 ? PROTOCOL_MINOR_2 : minor1, - SSH_VERSION); - if (atomicio(vwrite, connection_out, buf, strlen(buf)) != strlen(buf)) + SSH_VERSION, compat20 ? "\r\n" : "\n"); + if (roaming_atomicio(vwrite, connection_out, buf, strlen(buf)) + != strlen(buf)) fatal("write: %.100s", strerror(errno)); client_version_string = xstrdup(buf); chop(client_version_string); @@ -507,21 +580,25 @@ confirm(const char *prompt) * check whether the supplied host key is valid, return -1 if the key * is not valid. the user_hostfile will not be updated if 'readonly' is true. */ +#define RDRW 0 +#define RDONLY 1 +#define ROQUIET 2 static int -check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key, - int readonly, const char *user_hostfile, const char *system_hostfile) +check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port, + Key *host_key, int readonly, const char *user_hostfile, + const char *system_hostfile) { Key *file_key; const char *type = key_type(host_key); - char *ip = NULL; - char hostline[1000], *hostp, *fp; + char *ip = NULL, *host = NULL; + char hostline[1000], *hostp, *fp, *ra; HostStatus host_status; HostStatus ip_status; int r, local = 0, host_ip_differ = 0; int salen; char ntop[NI_MAXHOST]; char msg[1024]; - int len, host_line, ip_line; + int len, host_line, ip_line, cancelled_forwarding = 0; const char *host_file = NULL, *ip_file = NULL; /* @@ -564,26 +641,30 @@ check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key, if (getnameinfo(hostaddr, salen, ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST) != 0) fatal("check_host_key: getnameinfo failed"); - ip = xstrdup(ntop); + ip = put_host_port(ntop, port); } else { ip = xstrdup(""); } + /* * Turn off check_host_ip if the connection is to localhost, via proxy * command or if we don't have a hostname to compare with */ - if (options.check_host_ip && - (local || strcmp(host, ip) == 0 || options.proxy_command != NULL)) + if (options.check_host_ip && (local || + strcmp(hostname, ip) == 0 || options.proxy_command != NULL)) options.check_host_ip = 0; /* - * Allow the user to record the key under a different name. This is - * useful for ssh tunneling over forwarded connections or if you run - * multiple sshd's on different ports on the same machine. + * Allow the user to record the key under a different name or + * differentiate a non-standard port. This is useful for ssh + * tunneling over forwarded connections or if you run multiple + * sshd's on different ports on the same machine. */ if (options.host_key_alias != NULL) { - host = options.host_key_alias; + host = xstrdup(options.host_key_alias); debug("using hostkeyalias: %s", host); + } else { + host = put_host_port(hostname, port); } /* @@ -649,9 +730,25 @@ check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key, logit("Warning: Permanently added the %s host " "key for IP address '%.128s' to the list " "of known hosts.", type, ip); + } else if (options.visual_host_key) { + fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX); + ra = key_fingerprint(host_key, SSH_FP_MD5, + SSH_FP_RANDOMART); + logit("Host key fingerprint is %s\n%s\n", fp, ra); + xfree(ra); + xfree(fp); } break; case HOST_NEW: + if (options.host_key_alias == NULL && port != 0 && + port != SSH_DEFAULT_PORT) { + debug("checking without port identifier"); + if (check_host_key(hostname, hostaddr, 0, host_key, + ROQUIET, user_hostfile, system_hostfile) == 0) { + debug("found matching key w/out port"); + break; + } + } if (readonly) goto fail; /* The host is new. */ @@ -675,6 +772,8 @@ check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key, snprintf(msg1, sizeof(msg1), "."); /* The default */ fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX); + ra = key_fingerprint(host_key, SSH_FP_MD5, + SSH_FP_RANDOMART); msg2[0] = '\0'; if (options.verify_host_key_dns) { if (matching_host_key_dns) @@ -689,10 +788,14 @@ check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key, snprintf(msg, sizeof(msg), "The authenticity of host '%.200s (%s)' can't be " "established%s\n" - "%s key fingerprint is %s.\n%s" + "%s key fingerprint is %s.%s%s\n%s" "Are you sure you want to continue connecting " "(yes/no)? ", - host, ip, msg1, type, fp, msg2); + host, ip, msg1, type, fp, + options.visual_host_key ? "\n" : "", + options.visual_host_key ? ra : "", + msg2); + xfree(ra); xfree(fp); if (!confirm(msg)) goto fail; @@ -731,6 +834,8 @@ check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key, "list of known hosts.", hostp, type); break; case HOST_CHANGED: + if (readonly == ROQUIET) + goto fail; if (options.check_host_ip && host_ip_differ) { char *key_msg; if (ip_status == HOST_NEW) @@ -743,7 +848,7 @@ check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key, error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @"); error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); error("The %s host key for %s has changed,", type, host); - error("and the key for the according IP address %s", ip); + error("and the key for the corresponding IP address %s", ip); error("%s. This could either mean that", key_msg); error("DNS SPOOFING is happening or the IP address for the host"); error("and its host key have changed at the same time."); @@ -769,33 +874,38 @@ check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key, /* * If strict host key checking has not been requested, allow * the connection but without MITM-able authentication or - * agent forwarding. + * forwarding. */ if (options.password_authentication) { error("Password authentication is disabled to avoid " "man-in-the-middle attacks."); options.password_authentication = 0; + cancelled_forwarding = 1; } if (options.kbd_interactive_authentication) { error("Keyboard-interactive authentication is disabled" " to avoid man-in-the-middle attacks."); options.kbd_interactive_authentication = 0; options.challenge_response_authentication = 0; + cancelled_forwarding = 1; } if (options.challenge_response_authentication) { error("Challenge/response authentication is disabled" " to avoid man-in-the-middle attacks."); options.challenge_response_authentication = 0; + cancelled_forwarding = 1; } if (options.forward_agent) { error("Agent forwarding is disabled to avoid " "man-in-the-middle attacks."); options.forward_agent = 0; + cancelled_forwarding = 1; } if (options.forward_x11) { error("X11 forwarding is disabled to avoid " "man-in-the-middle attacks."); options.forward_x11 = 0; + cancelled_forwarding = 1; } if (options.num_local_forwards > 0 || options.num_remote_forwards > 0) { @@ -803,12 +913,23 @@ check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key, "man-in-the-middle attacks."); options.num_local_forwards = options.num_remote_forwards = 0; + cancelled_forwarding = 1; } + if (options.tun_open != SSH_TUNMODE_NO) { + error("Tunnel forwarding is disabled to avoid " + "man-in-the-middle attacks."); + options.tun_open = SSH_TUNMODE_NO; + cancelled_forwarding = 1; + } + if (options.exit_on_forward_failure && cancelled_forwarding) + fatal("Error: forwarding disabled due to host key " + "check failure"); + /* * XXX Should permit the user to change to use the new id. * This could be done by converting the host key to an * identifying sentence, tell that the host identifies itself - * by that sentence, and ask the user if he/she whishes to + * by that sentence, and ask the user if he/she wishes to * accept the authentication. */ break; @@ -845,10 +966,12 @@ check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key, } xfree(ip); + xfree(host); return 0; fail: xfree(ip); + xfree(host); return -1; } @@ -882,12 +1005,13 @@ verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key) /* return ok if the key can be found in an old keyfile */ if (stat(options.system_hostfile2, &st) == 0 || stat(options.user_hostfile2, &st) == 0) { - if (check_host_key(host, hostaddr, host_key, /*readonly*/ 1, - options.user_hostfile2, options.system_hostfile2) == 0) + if (check_host_key(host, hostaddr, options.port, host_key, + RDONLY, options.user_hostfile2, + options.system_hostfile2) == 0) return 0; } - return check_host_key(host, hostaddr, host_key, /*readonly*/ 0, - options.user_hostfile, options.system_hostfile); + return check_host_key(host, hostaddr, options.port, host_key, + RDRW, options.user_hostfile, options.system_hostfile); } /* @@ -899,7 +1023,7 @@ verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key) */ void ssh_login(Sensitive *sensitive, const char *orighost, - struct sockaddr *hostaddr, struct passwd *pw) + struct sockaddr *hostaddr, struct passwd *pw, int timeout_ms) { char *host, *cp; char *server_user, *local_user; @@ -914,7 +1038,7 @@ ssh_login(Sensitive *sensitive, const char *orighost, *cp = (char)tolower(*cp); /* Exchange protocol version identification strings with the server. */ - ssh_exchange_identification(); + ssh_exchange_identification(timeout_ms); /* Put the connection into non-blocking mode. */ packet_set_nonblocking(); @@ -953,18 +1077,20 @@ static int show_key_from_file(const char *file, const char *host, int keytype) { Key *found; - char *fp; + char *fp, *ra; int line, ret; found = key_new(keytype); if ((ret = lookup_key_in_hostfile_by_type(file, host, keytype, found, &line))) { fp = key_fingerprint(found, SSH_FP_MD5, SSH_FP_HEX); + ra = key_fingerprint(found, SSH_FP_MD5, SSH_FP_RANDOMART); logit("WARNING: %s key found for host %s\n" "in %s:%d\n" - "%s key fingerprint %s.", + "%s key fingerprint %s.\n%s\n", key_type(found), host, file, line, - key_type(found), fp); + key_type(found), fp, ra); + xfree(ra); xfree(fp); } key_free(found);