| /* $OpenBSD: sshconnect.c,v 1.205 2008/06/12 00:03:49 dtucker Exp $ */ |
| /* |
| * Author: Tatu Ylonen <ylo@cs.hut.fi> |
| * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland |
| * All rights reserved |
| * Code to connect to a remote host, and to perform the client side of the |
| * login (authentication) dialog. |
| * |
| * 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". |
| */ |
| |
| #include "includes.h" |
| |
| #include <sys/types.h> |
| #include <sys/wait.h> |
| #include <sys/stat.h> |
| #include <sys/socket.h> |
| #ifdef HAVE_SYS_TIME_H |
| # include <sys/time.h> |
| #endif |
| |
| #include <netinet/in.h> |
| #include <arpa/inet.h> |
| |
| #include <ctype.h> |
| #include <errno.h> |
| #include <netdb.h> |
| #ifdef HAVE_PATHS_H |
| #include <paths.h> |
| #endif |
| #include <pwd.h> |
| #include <stdarg.h> |
| #include <stdio.h> |
| #include <stdlib.h> |
| #include <string.h> |
| #include <unistd.h> |
| |
| #include "xmalloc.h" |
| #include "key.h" |
| #include "hostfile.h" |
| #include "ssh.h" |
| #include "rsa.h" |
| #include "buffer.h" |
| #include "packet.h" |
| #include "uidswap.h" |
| #include "compat.h" |
| #include "key.h" |
| #include "sshconnect.h" |
| #include "hostfile.h" |
| #include "log.h" |
| #include "readconf.h" |
| #include "atomicio.h" |
| #include "misc.h" |
| #include "dns.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; |
| 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 *); |
| |
| static void |
| ms_subtract_diff(struct timeval *start, int *ms) |
| { |
| struct timeval diff, finish; |
| |
| gettimeofday(&finish, NULL); |
| timersub(&finish, start, &diff); |
| *ms -= (diff.tv_sec * 1000) + (diff.tv_usec / 1000); |
| } |
| |
| static void |
| ms_to_timeval(struct timeval *tv, int ms) |
| { |
| tv->tv_sec = ms / 1000; |
| tv->tv_usec = (ms % 1000) * 1000; |
| } |
| |
| /* |
| * Connect to the given ssh server using a proxy command. |
| */ |
| static int |
| 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 *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. |
| * |
| * 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) |
| fatal("Could not create pipes to communicate with the proxy: %.100s", |
| strerror(errno)); |
| |
| debug("Executing proxy command: %.500s", command_string); |
| |
| /* Fork and execute the proxy command. */ |
| if ((pid = fork()) == 0) { |
| char *argv[10]; |
| |
| /* Child. Permanently give up superuser privileges. */ |
| permanently_drop_suid(original_real_uid); |
| |
| /* Redirect stdin and stdout. */ |
| close(pin[1]); |
| if (pin[0] != 0) { |
| if (dup2(pin[0], 0) < 0) |
| perror("dup2 stdin"); |
| close(pin[0]); |
| } |
| close(pout[0]); |
| if (dup2(pout[1], 1) < 0) |
| perror("dup2 stdout"); |
| /* Cannot be 1 because pin allocated two descriptors. */ |
| close(pout[1]); |
| |
| /* Stderr is left as it is so that error messages get |
| printed on the user's terminal. */ |
| argv[0] = shell; |
| argv[1] = "-c"; |
| argv[2] = command_string; |
| argv[3] = NULL; |
| |
| /* Execute the proxy command. Note that we gave up any |
| extra privileges above. */ |
| execv(argv[0], argv); |
| perror(argv[0]); |
| exit(1); |
| } |
| /* 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. */ |
| xfree(command_string); |
| |
| /* Set the connection file descriptors. */ |
| packet_set_connection(pout[0], pin[1]); |
| |
| /* Indicate OK return */ |
| return 0; |
| } |
| |
| /* |
| * Creates a (possibly privileged) socket for use as the ssh connection. |
| */ |
| static int |
| ssh_create_socket(int privileged, struct addrinfo *ai) |
| { |
| int sock, gaierr; |
| struct addrinfo hints, *res; |
| |
| /* |
| * If we are running as root and want to connect to a privileged |
| * port, bind our own socket to a privileged port. |
| */ |
| if (privileged) { |
| int p = IPPORT_RESERVED - 1; |
| PRIV_START; |
| sock = rresvport_af(&p, ai->ai_family); |
| PRIV_END; |
| if (sock < 0) |
| error("rresvport: af=%d %.100s", ai->ai_family, |
| strerror(errno)); |
| else |
| debug("Allocated local port %d.", p); |
| return sock; |
| } |
| sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol); |
| if (sock < 0) |
| error("socket: %.100s", strerror(errno)); |
| |
| /* Bind the socket to an alternative local IP address */ |
| if (options.bind_address == NULL) |
| return sock; |
| |
| memset(&hints, 0, sizeof(hints)); |
| 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, NULL, &hints, &res); |
| if (gaierr) { |
| error("getaddrinfo: %s: %s", options.bind_address, |
| ssh_gai_strerror(gaierr)); |
| close(sock); |
| return -1; |
| } |
| if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) { |
| error("bind: %s: %s", options.bind_address, strerror(errno)); |
| close(sock); |
| freeaddrinfo(res); |
| return -1; |
| } |
| freeaddrinfo(res); |
| 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. |
| * If port is 0, the default port will be used. If needpriv is true, |
| * a privileged port will be allocated to make the connection. |
| * This requires super-user privileges if needpriv is true. |
| * Connection_attempts specifies the maximum number of tries (one per |
| * 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. |
| */ |
| int |
| ssh_connect(const char *host, struct sockaddr_storage * hostaddr, |
| 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; |
| |
| debug2("ssh_connect: needpriv %d", needpriv); |
| |
| /* If a proxy command is given, connect using it. */ |
| if (proxy_command != NULL) |
| return ssh_proxy_connect(host, port, proxy_command); |
| |
| /* No proxy command. */ |
| |
| memset(&hints, 0, sizeof(hints)); |
| hints.ai_family = family; |
| hints.ai_socktype = SOCK_STREAM; |
| snprintf(strport, sizeof strport, "%u", port); |
| if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0) |
| fatal("%s: Could not resolve hostname %.100s: %s", __progname, |
| host, ssh_gai_strerror(gaierr)); |
| |
| 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. |
| */ |
| for (ai = aitop; ai; ai = ai->ai_next) { |
| if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) |
| continue; |
| if (getnameinfo(ai->ai_addr, ai->ai_addrlen, |
| ntop, sizeof(ntop), strport, sizeof(strport), |
| NI_NUMERICHOST|NI_NUMERICSERV) != 0) { |
| error("ssh_connect: getnameinfo failed"); |
| continue; |
| } |
| debug("Connecting to %.200s [%.100s] port %s.", |
| host, ntop, strport); |
| |
| /* Create a socket for connecting. */ |
| sock = ssh_create_socket(needpriv, ai); |
| if (sock < 0) |
| /* Any error is already output */ |
| continue; |
| |
| 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 { |
| debug("connect to address %s port %s: %s", |
| ntop, strport, strerror(errno)); |
| close(sock); |
| sock = -1; |
| } |
| } |
| if (sock != -1) |
| break; /* Successful connection. */ |
| } |
| |
| freeaddrinfo(aitop); |
| |
| /* Return failure if we didn't get a successful connection. */ |
| if (sock == -1) { |
| error("ssh: connect to host %s port %s: %s", |
| host, strport, strerror(errno)); |
| return (-1); |
| } |
| |
| debug("Connection established."); |
| |
| /* 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); |
| |
| return 0; |
| } |
| |
| /* |
| * Waits for the server identification string, and sends our own |
| * identification string. |
| */ |
| static 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, 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++) { |
| 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 = 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; |
| continue; /**XXX wait for \n */ |
| } |
| if (buf[i] == '\n') { |
| 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) |
| break; |
| debug("ssh_exchange_identification: %s", buf); |
| } |
| server_version_string = xstrdup(buf); |
| xfree(fdset); |
| |
| /* |
| * Check that the versions match. In future this might accept |
| * several versions and set appropriate flags to handle them. |
| */ |
| if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n", |
| &remote_major, &remote_minor, remote_version) != 3) |
| fatal("Bad remote protocol version identification: '%.100s'", buf); |
| debug("Remote protocol version %d.%d, remote software version %.100s", |
| remote_major, remote_minor, remote_version); |
| |
| compat_datafellows(remote_version); |
| mismatch = 0; |
| |
| switch (remote_major) { |
| case 1: |
| if (remote_minor == 99 && |
| (options.protocol & SSH_PROTO_2) && |
| !(options.protocol & SSH_PROTO_1_PREFERRED)) { |
| enable_compat20(); |
| break; |
| } |
| if (!(options.protocol & SSH_PROTO_1)) { |
| mismatch = 1; |
| break; |
| } |
| if (remote_minor < 3) { |
| fatal("Remote machine has too old SSH software version."); |
| } else if (remote_minor == 3 || remote_minor == 4) { |
| /* We speak 1.3, too. */ |
| enable_compat13(); |
| minor1 = 3; |
| if (options.forward_agent) { |
| logit("Agent forwarding disabled for protocol 1.3"); |
| options.forward_agent = 0; |
| } |
| } |
| break; |
| case 2: |
| if (options.protocol & SSH_PROTO_2) { |
| enable_compat20(); |
| break; |
| } |
| /* FALLTHROUGH */ |
| default: |
| mismatch = 1; |
| break; |
| } |
| if (mismatch) |
| fatal("Protocol major versions differ: %d vs. %d", |
| (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", |
| compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1, |
| compat20 ? PROTOCOL_MINOR_2 : minor1, |
| SSH_VERSION); |
| if (atomicio(vwrite, connection_out, buf, strlen(buf)) != strlen(buf)) |
| fatal("write: %.100s", strerror(errno)); |
| client_version_string = xstrdup(buf); |
| chop(client_version_string); |
| chop(server_version_string); |
| debug("Local version string %.100s", client_version_string); |
| } |
| |
| /* defaults to 'no' */ |
| static int |
| confirm(const char *prompt) |
| { |
| const char *msg, *again = "Please type 'yes' or 'no': "; |
| char *p; |
| int ret = -1; |
| |
| if (options.batch_mode) |
| return 0; |
| for (msg = prompt;;msg = again) { |
| p = read_passphrase(msg, RP_ECHO); |
| if (p == NULL || |
| (p[0] == '\0') || (p[0] == '\n') || |
| strncasecmp(p, "no", 2) == 0) |
| ret = 0; |
| if (p && strncasecmp(p, "yes", 3) == 0) |
| ret = 1; |
| if (p) |
| xfree(p); |
| if (ret != -1) |
| return ret; |
| } |
| } |
| |
| /* |
| * 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 *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, *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; |
| const char *host_file = NULL, *ip_file = NULL; |
| |
| /* |
| * Force accepting of the host key for loopback/localhost. The |
| * problem is that if the home directory is NFS-mounted to multiple |
| * machines, localhost will refer to a different machine in each of |
| * them, and the user will get bogus HOST_CHANGED warnings. This |
| * essentially disables host authentication for localhost; however, |
| * this is probably not a real problem. |
| */ |
| /** hostaddr == 0! */ |
| switch (hostaddr->sa_family) { |
| case AF_INET: |
| local = (ntohl(((struct sockaddr_in *)hostaddr)-> |
| sin_addr.s_addr) >> 24) == IN_LOOPBACKNET; |
| salen = sizeof(struct sockaddr_in); |
| break; |
| case AF_INET6: |
| local = IN6_IS_ADDR_LOOPBACK( |
| &(((struct sockaddr_in6 *)hostaddr)->sin6_addr)); |
| salen = sizeof(struct sockaddr_in6); |
| break; |
| default: |
| local = 0; |
| salen = sizeof(struct sockaddr_storage); |
| break; |
| } |
| if (options.no_host_authentication_for_localhost == 1 && local && |
| options.host_key_alias == NULL) { |
| debug("Forcing accepting of host key for " |
| "loopback/localhost."); |
| return 0; |
| } |
| |
| /* |
| * We don't have the remote ip-address for connections |
| * using a proxy command |
| */ |
| if (options.proxy_command == NULL) { |
| if (getnameinfo(hostaddr, salen, ntop, sizeof(ntop), |
| NULL, 0, NI_NUMERICHOST) != 0) |
| fatal("check_host_key: getnameinfo failed"); |
| ip = put_host_port(ntop, port); |
| } else { |
| ip = xstrdup("<no hostip for proxy command>"); |
| } |
| /* |
| * 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(hostname, ip) == 0 || options.proxy_command != NULL)) |
| options.check_host_ip = 0; |
| |
| /* |
| * 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 = xstrdup(options.host_key_alias); |
| debug("using hostkeyalias: %s", host); |
| } else { |
| host = put_host_port(hostname, port); |
| } |
| |
| /* |
| * Store the host key from the known host file in here so that we can |
| * compare it with the key for the IP address. |
| */ |
| file_key = key_new(host_key->type); |
| |
| /* |
| * Check if the host key is present in the user's list of known |
| * hosts or in the systemwide list. |
| */ |
| host_file = user_hostfile; |
| host_status = check_host_in_hostfile(host_file, host, host_key, |
| file_key, &host_line); |
| if (host_status == HOST_NEW) { |
| host_file = system_hostfile; |
| host_status = check_host_in_hostfile(host_file, host, host_key, |
| file_key, &host_line); |
| } |
| /* |
| * Also perform check for the ip address, skip the check if we are |
| * localhost or the hostname was an ip address to begin with |
| */ |
| if (options.check_host_ip) { |
| Key *ip_key = key_new(host_key->type); |
| |
| ip_file = user_hostfile; |
| ip_status = check_host_in_hostfile(ip_file, ip, host_key, |
| ip_key, &ip_line); |
| if (ip_status == HOST_NEW) { |
| ip_file = system_hostfile; |
| ip_status = check_host_in_hostfile(ip_file, ip, |
| host_key, ip_key, &ip_line); |
| } |
| if (host_status == HOST_CHANGED && |
| (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key))) |
| host_ip_differ = 1; |
| |
| key_free(ip_key); |
| } else |
| ip_status = host_status; |
| |
| key_free(file_key); |
| |
| switch (host_status) { |
| case HOST_OK: |
| /* The host is known and the key matches. */ |
| debug("Host '%.200s' is known and matches the %s host key.", |
| host, type); |
| debug("Found key in %s:%d", host_file, host_line); |
| if (options.check_host_ip && ip_status == HOST_NEW) { |
| if (readonly) |
| 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, 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 |
| logit("Warning: Permanently added the %s host " |
| "key for IP address '%.128s' to the list " |
| "of known hosts.", type, ip); |
| } else if (options.check_host_ip == SSHCTL_CHECKHOSTIP_FPR) { |
| 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, 2, |
| user_hostfile, system_hostfile) == 0) { |
| debug("found matching key w/out port"); |
| break; |
| } |
| } |
| if (readonly) |
| goto fail; |
| /* The host is new. */ |
| if (options.strict_host_key_checking == 1) { |
| /* |
| * User has requested strict host key checking. We |
| * will not add the host key automatically. The only |
| * alternative left is to abort. |
| */ |
| error("No %s host key is known for %.200s and you " |
| "have requested strict checking.", type, host); |
| goto fail; |
| } else if (options.strict_host_key_checking == 2) { |
| 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\n%s" |
| "Are you sure you want to continue connecting " |
| "(yes/no)? ", |
| host, ip, msg1, type, fp, ra, msg2); |
| xfree(ra); |
| xfree(fp); |
| if (!confirm(msg)) |
| goto fail; |
| } |
| /* |
| * If not in strict mode, add the key automatically to the |
| * local known_hosts file. |
| */ |
| 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 |
| 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 *key_msg; |
| if (ip_status == HOST_NEW) |
| key_msg = "is unknown"; |
| else if (ip_status == HOST_OK) |
| key_msg = "is unchanged"; |
| else |
| 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", 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. */ |
| 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); |
| |
| /* |
| * If strict host key checking is in use, the user will have |
| * to edit the key manually and we can only abort. |
| */ |
| if (options.strict_host_key_checking) { |
| error("%s host key for %.200s has changed and you have " |
| "requested strict checking.", type, host); |
| goto fail; |
| } |
| |
| /* |
| * If strict host key checking has not been requested, allow |
| * 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; |
| } |
| 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; |
| } |
| if (options.challenge_response_authentication) { |
| error("Challenge/response authentication is disabled" |
| " to avoid man-in-the-middle attacks."); |
| options.challenge_response_authentication = 0; |
| } |
| if (options.forward_agent) { |
| error("Agent forwarding is disabled to avoid " |
| "man-in-the-middle attacks."); |
| options.forward_agent = 0; |
| } |
| if (options.forward_x11) { |
| error("X11 forwarding is disabled to avoid " |
| "man-in-the-middle attacks."); |
| options.forward_x11 = 0; |
| } |
| if (options.num_local_forwards > 0 || |
| options.num_remote_forwards > 0) { |
| error("Port forwarding is disabled to avoid " |
| "man-in-the-middle attacks."); |
| options.num_local_forwards = |
| options.num_remote_forwards = 0; |
| } |
| 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; |
| } |
| /* |
| * 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 |
| * accept the authentication. |
| */ |
| break; |
| case HOST_FOUND: |
| fatal("internal error"); |
| break; |
| } |
| |
| if (options.check_host_ip && host_status != HOST_CHANGED && |
| ip_status == HOST_CHANGED) { |
| snprintf(msg, sizeof(msg), |
| "Warning: the %s host key for '%.200s' " |
| "differs from the key for the IP address '%.128s'" |
| "\nOffending key for IP in %s:%d", |
| type, host, ip, ip_file, ip_line); |
| if (host_status == HOST_OK) { |
| len = strlen(msg); |
| snprintf(msg + len, sizeof(msg) - len, |
| "\nMatching host key in %s:%d", |
| host_file, host_line); |
| } |
| if (options.strict_host_key_checking == 1) { |
| logit("%s", msg); |
| error("Exiting, you have requested strict checking."); |
| goto fail; |
| } else if (options.strict_host_key_checking == 2) { |
| strlcat(msg, "\nAre you sure you want " |
| "to continue connecting (yes/no)? ", sizeof(msg)); |
| if (!confirm(msg)) |
| goto fail; |
| } else { |
| 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, options.port, host_key, |
| RDONLY, options.user_hostfile2, |
| options.system_hostfile2) == 0) |
| return 0; |
| } |
| return check_host_key(host, hostaddr, options.port, host_key, |
| RDRW, options.user_hostfile, options.system_hostfile); |
| } |
| |
| /* |
| * Starts a dialog with the server, and authenticates the current user on the |
| * server. This does not need any extra privileges. The basic connection |
| * to the server must already have been established before this is called. |
| * If login fails, this function prints an error and never returns. |
| * This function does not require super-user privileges. |
| */ |
| void |
| ssh_login(Sensitive *sensitive, const char *orighost, |
| struct sockaddr *hostaddr, struct passwd *pw, int timeout_ms) |
| { |
| char *host, *cp; |
| char *server_user, *local_user; |
| |
| local_user = xstrdup(pw->pw_name); |
| server_user = options.user ? options.user : local_user; |
| |
| /* Convert the user-supplied hostname into all lowercase. */ |
| host = xstrdup(orighost); |
| for (cp = host; *cp; cp++) |
| if (isupper(*cp)) |
| *cp = (char)tolower(*cp); |
| |
| /* Exchange protocol version identification strings with the server. */ |
| ssh_exchange_identification(timeout_ms); |
| |
| /* Put the connection into non-blocking mode. */ |
| packet_set_nonblocking(); |
| |
| /* key exchange */ |
| /* authenticate user */ |
| if (compat20) { |
| ssh_kex2(host, hostaddr); |
| ssh_userauth2(local_user, server_user, host, sensitive); |
| } else { |
| ssh_kex(host, hostaddr); |
| ssh_userauth1(local_user, server_user, host, sensitive); |
| } |
| xfree(local_user); |
| } |
| |
| void |
| ssh_put_password(char *password) |
| { |
| int size; |
| char *padded; |
| |
| if (datafellows & SSH_BUG_PASSWORDPAD) { |
| packet_put_cstring(password); |
| return; |
| } |
| size = roundup(strlen(password) + 1, 32); |
| padded = xcalloc(1, size); |
| strlcpy(padded, password, size); |
| packet_put_string(padded, size); |
| memset(padded, 0, size); |
| xfree(padded); |
| } |
| |
| static int |
| show_key_from_file(const char *file, const char *host, int keytype) |
| { |
| Key *found; |
| 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.\n%s\n", |
| key_type(found), host, file, line, |
| key_type(found), fp, ra); |
| xfree(ra); |
| xfree(fp); |
| } |
| key_free(found); |
| return (ret); |
| } |
| |
| /* print all known host keys for a given host, but skip keys of given type */ |
| static int |
| show_other_keys(const char *host, Key *key) |
| { |
| int type[] = { KEY_RSA1, KEY_RSA, KEY_DSA, -1}; |
| int i, found = 0; |
| |
| for (i = 0; type[i] != -1; i++) { |
| if (type[i] == key->type) |
| continue; |
| if (type[i] != KEY_RSA1 && |
| show_key_from_file(options.user_hostfile2, host, type[i])) { |
| found = 1; |
| continue; |
| } |
| if (type[i] != KEY_RSA1 && |
| show_key_from_file(options.system_hostfile2, host, type[i])) { |
| found = 1; |
| continue; |
| } |
| if (show_key_from_file(options.user_hostfile, host, type[i])) { |
| found = 1; |
| continue; |
| } |
| if (show_key_from_file(options.system_hostfile, host, type[i])) { |
| found = 1; |
| continue; |
| } |
| debug2("no key of type %d for host %s", type[i], host); |
| } |
| 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)); |
| } |