X-Git-Url: http://andersk.mit.edu/gitweb/openssh.git/blobdiff_plain/facfd6138d0be3f11967dbec771aa2bc2d52fa4f..HEAD:/sshconnect.c diff --git a/sshconnect.c b/sshconnect.c index 0cb82485..63c4650f 100644 --- a/sshconnect.c +++ b/sshconnect.c @@ -1,3 +1,4 @@ +/* $OpenBSD: sshconnect.c,v 1.218 2010/01/13 00:19:04 dtucker Exp $ */ /* * Author: Tatu Ylonen * Copyright (c) 1995 Tatu Ylonen , Espoo, Finland @@ -13,12 +14,36 @@ */ #include "includes.h" -RCSID("$OpenBSD: sshconnect.c,v 1.134 2002/09/13 19:23:09 stevesk Exp $"); -#include +#include +#include +#include +#include +#ifdef HAVE_SYS_TIME_H +# include +#endif + +#include +#include + +#include +#include +#include +#include +#ifdef HAVE_PATHS_H +#include +#endif +#include +#include +#include +#include +#include +#include -#include "ssh.h" #include "xmalloc.h" +#include "key.h" +#include "hostfile.h" +#include "ssh.h" #include "rsa.h" #include "buffer.h" #include "packet.h" @@ -31,22 +56,24 @@ RCSID("$OpenBSD: sshconnect.c,v 1.134 2002/09/13 19:23:09 stevesk Exp $"); #include "readconf.h" #include "atomicio.h" #include "misc.h" -#include "readpass.h" +#include "dns.h" +#include "roaming.h" +#include "version.h" char *client_version_string = NULL; char *server_version_string = NULL; +static int matching_host_key_dns = 0; + /* import */ extern Options options; extern char *__progname; extern uid_t original_real_uid; extern uid_t original_effective_uid; - -#ifndef INET6_ADDRSTRLEN /* for non IPv6 machines */ -#define INET6_ADDRSTRLEN 46 -#endif +extern pid_t proxy_command_pid; static int show_other_keys(const char *, Key *); +static void warn_changed_key(Key *); /* * Connect to the given ssh server using a proxy command. @@ -54,41 +81,28 @@ static int show_other_keys(const char *, Key *); static int ssh_proxy_connect(const char *host, u_short port, const char *proxy_command) { - Buffer command; - const char *cp; - char *command_string; + 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); - /* Build the final command string in the buffer by making the - appropriate substitutions to the given proxy command. */ - buffer_init(&command); - for (cp = proxy_command; *cp; cp++) { - if (cp[0] == '%' && cp[1] == '%') { - buffer_append(&command, "%", 1); - cp++; - continue; - } - if (cp[0] == '%' && cp[1] == 'h') { - buffer_append(&command, host, strlen(host)); - cp++; - continue; - } - if (cp[0] == '%' && cp[1] == 'p') { - buffer_append(&command, strport, strlen(strport)); - cp++; - continue; - } - buffer_append(&command, cp, 1); - } - buffer_append(&command, "\0", 1); - - /* Get the final command string. */ - command_string = buffer_ptr(&command); + /* + * Build the final command string in the buffer by making the + * appropriate substitutions to the given proxy command. + * + * Use "exec" to avoid "sh -c" processes on some platforms + * (e.g. Solaris) + */ + xasprintf(&tmp, "exec %s", proxy_command); + command_string = percent_expand(tmp, "h", host, + "p", strport, (char *)NULL); + xfree(tmp); /* Create pipes for communicating with the proxy. */ if (pipe(pin) < 0 || pipe(pout) < 0) @@ -102,8 +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]); @@ -120,7 +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; @@ -134,16 +147,20 @@ ssh_proxy_connect(const char *host, u_short port, const char *proxy_command) /* Parent. */ if (pid < 0) fatal("fork failed: %.100s", strerror(errno)); + else + proxy_command_pid = pid; /* save pid to clean up later */ /* Close child side of the descriptors. */ close(pin[0]); close(pout[1]); /* Free the command name. */ - buffer_free(&command); + xfree(command_string); /* 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; @@ -153,7 +170,7 @@ ssh_proxy_connect(const char *host, u_short port, const char *proxy_command) * Creates a (possibly privileged) socket for use as the ssh connection. */ static int -ssh_create_socket(int privileged, int family) +ssh_create_socket(int privileged, struct addrinfo *ai) { int sock, gaierr; struct addrinfo hints, *res; @@ -165,30 +182,35 @@ ssh_create_socket(int privileged, int family) if (privileged) { int p = IPPORT_RESERVED - 1; PRIV_START; - sock = rresvport_af(&p, family); + sock = rresvport_af(&p, ai->ai_family); PRIV_END; if (sock < 0) - error("rresvport: af=%d %.100s", family, strerror(errno)); + error("rresvport: af=%d %.100s", ai->ai_family, + strerror(errno)); else debug("Allocated local port %d.", p); return sock; } - sock = socket(family, SOCK_STREAM, 0); - if (sock < 0) + sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol); + 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) return sock; memset(&hints, 0, sizeof(hints)); - hints.ai_family = family; - hints.ai_socktype = SOCK_STREAM; + hints.ai_family = ai->ai_family; + 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; } @@ -202,6 +224,89 @@ ssh_create_socket(int privileged, int family) return sock; } +static int +timeout_connect(int sockfd, const struct sockaddr *serv_addr, + socklen_t addrlen, int *timeoutp) +{ + fd_set *fdset; + struct timeval tv, t_start; + socklen_t optlen; + int optval, rc, result = -1; + + 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); + result = 0; + goto done; + } + if (errno != EINPROGRESS) { + result = -1; + goto done; + } + + fdset = (fd_set *)xcalloc(howmany(sockfd + 1, NFDBITS), + sizeof(fd_mask)); + FD_SET(sockfd, fdset); + ms_to_timeval(&tv, *timeoutp); + + for (;;) { + rc = select(sockfd + 1, NULL, fdset, NULL, &tv); + if (rc != -1 || errno != EINTR) + break; + } + + switch (rc) { + case 0: + /* Timed out */ + errno = ETIMEDOUT; + break; + case -1: + /* Select error */ + debug("select: %s", strerror(errno)); + break; + case 1: + /* Completed or failed */ + optval = 0; + optlen = sizeof(optval); + if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &optval, + &optlen) == -1) { + debug("getsockopt: %s", strerror(errno)); + break; + } + if (optval != 0) { + errno = optval; + break; + } + result = 0; + unset_nonblock(sockfd); + break; + default: + /* Should not occur */ + fatal("Bogus return (%d) from select()", rc); + } + + xfree(fdset); + + done: + if (result == 0 && *timeoutp > 0) { + ms_subtract_diff(&t_start, timeoutp); + if (*timeoutp <= 0) { + errno = ETIMEDOUT; + result = -1; + } + } + + return (result); +} + /* * Opens a TCP/IP connection to the remote server on the given host. * The address of the remote host will be returned in hostaddr. @@ -212,41 +317,20 @@ ssh_create_socket(int privileged, int family) * second). If proxy_command is non-NULL, it specifies the command (with %h * and %p substituted for host and port, respectively) to use to contact * the daemon. - * Return values: - * 0 for OK - * ECONNREFUSED if we got a "Connection Refused" by the peer on any address - * ECONNABORTED if we failed without a "Connection refused" - * Suitable error messages for the connection failure will already have been - * printed. */ 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; int sock = -1, attempt; char ntop[NI_MAXHOST], strport[NI_MAXSERV]; struct addrinfo hints, *ai, *aitop; - struct servent *sp; - /* - * Did we get only other errors than "Connection refused" (which - * should block fallback to rsh and similar), or did we get at least - * one "Connection refused"? - */ - int full_failure = 1; - debug("ssh_connect: needpriv %d", needpriv); + debug2("ssh_connect: needpriv %d", needpriv); - /* Get default port if port has not been set. */ - if (port == 0) { - sp = getservbyname(SSH_SERVICE_NAME, "tcp"); - if (sp) - port = ntohs(sp->s_port); - else - port = SSH_DEFAULT_PORT; - } /* If a proxy command is given, connect using it. */ if (proxy_command != NULL) return ssh_proxy_connect(host, port, proxy_command); @@ -258,20 +342,19 @@ 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)); - /* - * Try to connect several times. On some machines, the first time - * will sometimes fail. In general socket code appears to behave - * quite magically on many machines. - */ - for (attempt = 0; ;) { - if (attempt > 0) + for (attempt = 0; attempt < connection_attempts; attempt++) { + 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. */ + } + /* + * Loop through addresses for this host, and try each one in + * sequence until the connection succeeds. + */ for (ai = aitop; ai; ai = ai->ai_next) { if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) continue; @@ -285,58 +368,48 @@ ssh_connect(const char *host, struct sockaddr_storage * hostaddr, host, ntop, strport); /* Create a socket for connecting. */ - sock = ssh_create_socket(needpriv, ai->ai_family); + sock = ssh_create_socket(needpriv, ai); if (sock < 0) /* Any error is already output */ continue; - if (connect(sock, ai->ai_addr, ai->ai_addrlen) >= 0) { + if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen, + timeout_ms) >= 0) { /* Successful connection. */ memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen); break; } else { - if (errno == ECONNREFUSED) - full_failure = 0; debug("connect to address %s port %s: %s", ntop, strport, strerror(errno)); - /* - * Close the failed socket; there appear to - * be some problems when reusing a socket for - * which connect() has already returned an - * error. - */ close(sock); + sock = -1; } } - if (ai) + if (sock != -1) break; /* Successful connection. */ - - attempt++; - if (attempt >= connection_attempts) - break; - /* Sleep a moment before retrying. */ - sleep(1); } freeaddrinfo(aitop); /* Return failure if we didn't get a successful connection. */ - if (attempt >= connection_attempts) { - log("ssh: connect to host %s port %s: %s", + if (sock == -1) { + error("ssh: connect to host %s port %s: %s", host, strport, strerror(errno)); - return full_failure ? ECONNABORTED : ECONNREFUSED; + return (-1); } debug("Connection established."); - /* Set keepalives if requested. */ - if (options.keepalives && + /* Set SO_KEEPALIVE if requested. */ + 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; } @@ -345,23 +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, i, mismatch; + 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; - - /* Read other side\'s version identification. */ - for (;;) { + 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. */ + remaining = timeout_ms; + for (n = 0;;) { for (i = 0; i < sizeof(buf) - 1; i++) { - int len = atomicio(read, connection_in, &buf[i], 1); - if (len < 0) - fatal("ssh_exchange_identification: read: %.100s", strerror(errno)); - if (len != 1) - fatal("ssh_exchange_identification: Connection closed by remote host"); + 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"); + else if (len != 1) + fatal("ssh_exchange_identification: " + "read: %.100s", strerror(errno)); if (buf[i] == '\r') { buf[i] = '\n'; buf[i + 1] = 0; @@ -371,6 +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) @@ -378,6 +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 @@ -411,7 +518,7 @@ ssh_exchange_identification(void) enable_compat13(); minor1 = 3; if (options.forward_agent) { - log("Agent forwarding disabled for protocol 1.3"); + logit("Agent forwarding disabled for protocol 1.3"); options.forward_agent = 0; } } @@ -431,11 +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(write, 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); @@ -472,21 +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; - char *type = key_type(host_key); - char *ip = NULL; - char hostline[1000], *hostp, *fp; + const char *type = key_type(host_key); + char *ip = NULL, *host = NULL; + char hostline[1000], *hostp, *fp, *ra; HostStatus host_status; HostStatus ip_status; - int local = 0, host_ip_differ = 0; + int r, local = 0, host_ip_differ = 0; int salen; char ntop[NI_MAXHOST]; char msg[1024]; - int len, host_line, ip_line, has_keys; + int len, host_line, ip_line, cancelled_forwarding = 0; const char *host_file = NULL, *ip_file = NULL; /* @@ -501,7 +613,7 @@ check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key, switch (hostaddr->sa_family) { case AF_INET: local = (ntohl(((struct sockaddr_in *)hostaddr)-> - sin_addr.s_addr) >> 24) == IN_LOOPBACKNET; + sin_addr.s_addr) >> 24) == IN_LOOPBACKNET; salen = sizeof(struct sockaddr_in); break; case AF_INET6: @@ -529,26 +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); } /* @@ -558,7 +674,7 @@ check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key, file_key = key_new(host_key->type); /* - * Check if the host key is present in the user\'s list of known + * Check if the host key is present in the user's list of known * hosts or in the systemwide list. */ host_file = user_hostfile; @@ -602,21 +718,37 @@ check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key, debug("Found key in %s:%d", host_file, host_line); if (options.check_host_ip && ip_status == HOST_NEW) { if (readonly) - log("%s host key for IP address " + logit("%s host key for IP address " "'%.128s' not in list of known hosts.", type, ip); else if (!add_host_to_hostfile(user_hostfile, ip, - host_key)) - log("Failed to add the %s host key for IP " + host_key, options.hash_known_hosts)) + logit("Failed to add the %s host key for IP " "address '%.128s' to the list of known " "hosts (%.30s).", type, ip, user_hostfile); else - log("Warning: Permanently added the %s host " + 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. */ @@ -630,75 +762,104 @@ check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key, "have requested strict checking.", type, host); goto fail; } else if (options.strict_host_key_checking == 2) { - has_keys = show_other_keys(host, host_key); + char msg1[1024], msg2[1024]; + + if (show_other_keys(host, host_key)) + snprintf(msg1, sizeof(msg1), + "\nbut keys of different type are already" + " known for this host."); + else + 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) + snprintf(msg2, sizeof(msg2), + "Matching host key fingerprint" + " found in DNS.\n"); + else + snprintf(msg2, sizeof(msg2), + "No matching host key fingerprint" + " found in DNS.\n"); + } snprintf(msg, sizeof(msg), "The authenticity of host '%.200s (%s)' can't be " "established%s\n" - "%s key fingerprint is %s.\n" + "%s key fingerprint is %s.%s%s\n%s" "Are you sure you want to continue connecting " "(yes/no)? ", - host, ip, - has_keys ? ",\nbut keys of different type are already " - "known for this host." : ".", - type, fp); + 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; } - if (options.check_host_ip && ip_status == HOST_NEW) { - snprintf(hostline, sizeof(hostline), "%s,%s", host, ip); - hostp = hostline; - } else - hostp = host; - /* * If not in strict mode, add the key automatically to the * local known_hosts file. */ - if (!add_host_to_hostfile(user_hostfile, hostp, host_key)) - log("Failed to add the host to the list of known " + if (options.check_host_ip && ip_status == HOST_NEW) { + snprintf(hostline, sizeof(hostline), "%s,%s", + host, ip); + hostp = hostline; + if (options.hash_known_hosts) { + /* Add hash of host and IP separately */ + r = add_host_to_hostfile(user_hostfile, host, + host_key, options.hash_known_hosts) && + add_host_to_hostfile(user_hostfile, ip, + host_key, options.hash_known_hosts); + } else { + /* Add unhashed "host,ip" */ + r = add_host_to_hostfile(user_hostfile, + hostline, host_key, + options.hash_known_hosts); + } + } else { + r = add_host_to_hostfile(user_hostfile, host, host_key, + options.hash_known_hosts); + hostp = host; + } + + if (!r) + logit("Failed to add the host to the list of known " "hosts (%.500s).", user_hostfile); else - log("Warning: Permanently added '%.200s' (%s) to the " + logit("Warning: Permanently added '%.200s' (%s) to the " "list of known hosts.", hostp, type); break; case HOST_CHANGED: + if (readonly == ROQUIET) + goto fail; if (options.check_host_ip && host_ip_differ) { - char *msg; + char *key_msg; if (ip_status == HOST_NEW) - msg = "is unknown"; + key_msg = "is unknown"; else if (ip_status == HOST_OK) - msg = "is unchanged"; + key_msg = "is unchanged"; else - msg = "has a different value"; + key_msg = "has a different value"; error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); 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("%s. This could either mean that", msg); + 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."); if (ip_status != HOST_NEW) error("Offending key for IP in %s:%d", ip_file, ip_line); } /* The host key has changed. */ - fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX); - error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); - error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @"); - error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); - error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!"); - error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!"); - error("It is also possible that the %s host key has just been changed.", type); - error("The fingerprint for the %s key sent by the remote host is\n%s.", - type, fp); - error("Please contact your system administrator."); + warn_changed_key(host_key); error("Add correct host key in %.100s to get rid of this message.", user_hostfile); error("Offending key in %s:%d", host_file, host_line); - xfree(fp); /* * If strict host key checking is in use, the user will have @@ -712,23 +873,39 @@ 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 password authentication or - * agent forwarding. + * the connection but without MITM-able authentication or + * 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) { @@ -736,12 +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; @@ -764,7 +952,7 @@ check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key, host_file, host_line); } if (options.strict_host_key_checking == 1) { - log(msg); + logit("%s", msg); error("Exiting, you have requested strict checking."); goto fail; } else if (options.strict_host_key_checking == 2) { @@ -773,32 +961,57 @@ check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key, if (!confirm(msg)) goto fail; } else { - log(msg); + logit("%s", msg); } } xfree(ip); + xfree(host); return 0; fail: xfree(ip); + xfree(host); return -1; } +/* returns 0 if key verifies or -1 if key does NOT verify */ int verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key) { struct stat st; + int flags = 0; + + if (options.verify_host_key_dns && + verify_host_key_dns(host, hostaddr, host_key, &flags) == 0) { + + if (flags & DNS_VERIFY_FOUND) { + + if (options.verify_host_key_dns == 1 && + flags & DNS_VERIFY_MATCH && + flags & DNS_VERIFY_SECURE) + return 0; + + if (flags & DNS_VERIFY_MATCH) { + matching_host_key_dns = 1; + } else { + warn_changed_key(host_key); + error("Update the SSHFP RR in DNS with the new " + "host key to get rid of this message."); + } + } + } /* 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); } /* @@ -810,7 +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; @@ -822,10 +1035,10 @@ ssh_login(Sensitive *sensitive, const char *orighost, host = xstrdup(orighost); for (cp = host; *cp; cp++) if (isupper(*cp)) - *cp = tolower(*cp); + *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(); @@ -839,6 +1052,7 @@ ssh_login(Sensitive *sensitive, const char *orighost, ssh_kex(host, hostaddr); ssh_userauth1(local_user, server_user, host, sensitive); } + xfree(local_user); } void @@ -852,8 +1066,7 @@ ssh_put_password(char *password) return; } size = roundup(strlen(password) + 1, 32); - padded = xmalloc(size); - memset(padded, 0, size); + padded = xcalloc(1, size); strlcpy(padded, password, size); packet_put_string(padded, size); memset(padded, 0, size); @@ -864,18 +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); - log("WARNING: %s key found for host %s\n" + 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); @@ -914,3 +1129,60 @@ show_other_keys(const char *host, Key *key) } return (found); } + +static void +warn_changed_key(Key *host_key) +{ + char *fp; + const char *type = key_type(host_key); + + fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX); + + error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); + error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @"); + error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); + error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!"); + error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!"); + error("It is also possible that the %s host key has just been changed.", type); + error("The fingerprint for the %s key sent by the remote host is\n%s.", + type, fp); + error("Please contact your system administrator."); + + xfree(fp); +} + +/* + * Execute a local command + */ +int +ssh_local_cmd(const char *args) +{ + char *shell; + pid_t pid; + int status; + + if (!options.permit_local_command || + args == NULL || !*args) + return (1); + + if ((shell = getenv("SHELL")) == NULL) + shell = _PATH_BSHELL; + + pid = fork(); + if (pid == 0) { + debug3("Executing %s -c \"%s\"", shell, args); + execl(shell, shell, "-c", args, (char *)NULL); + error("Couldn't execute %s -c \"%s\": %s", + shell, args, strerror(errno)); + _exit(1); + } else if (pid == -1) + fatal("fork failed: %.100s", strerror(errno)); + while (waitpid(pid, &status, 0) == -1) + if (errno != EINTR) + fatal("Couldn't wait for child: %s", strerror(errno)); + + if (!WIFEXITED(status)) + return (1); + + return (WEXITSTATUS(status)); +}