diff options
Diffstat (limited to 'crypto/openssh/sshconnect.c')
| -rw-r--r-- | crypto/openssh/sshconnect.c | 1106 |
1 files changed, 0 insertions, 1106 deletions
diff --git a/crypto/openssh/sshconnect.c b/crypto/openssh/sshconnect.c deleted file mode 100644 index a222233..0000000 --- a/crypto/openssh/sshconnect.c +++ /dev/null @@ -1,1106 +0,0 @@ -/* $OpenBSD: sshconnect.c,v 1.200 2006/10/10 10:12:45 markus 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 *); - -/* - * 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 strport[NI_MAXSERV]; - - /* 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] = _PATH_BSHELL; - 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, "0", &hints, &res); - if (gaierr) { - error("getaddrinfo: %s: %s", options.bind_address, - 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 timeout) -{ - fd_set *fdset; - struct timeval tv; - socklen_t optlen; - int optval, rc, result = -1; - - if (timeout <= 0) - return (connect(sockfd, serv_addr, addrlen)); - - set_nonblock(sockfd); - rc = connect(sockfd, serv_addr, addrlen); - if (rc == 0) { - unset_nonblock(sockfd); - return (0); - } - 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; - - 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); - 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 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: %.100s: %s", __progname, host, - 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, - options.connection_timeout) >= 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 (options.tcp_keep_alive && - 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(void) -{ - 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; - - /* Read other side's version identification. */ - for (n = 0;;) { - for (i = 0; i < sizeof(buf) - 1; i++) { - size_t 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); - - /* - * 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; - 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); - } - 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); - 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" - "Are you sure you want to continue connecting " - "(yes/no)? ", - host, ip, msg1, type, fp, msg2); - 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) -{ - 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(); - - /* 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; - 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); - logit("WARNING: %s key found for host %s\n" - "in %s:%d\n" - "%s key fingerprint %s.", - key_type(found), host, file, line, - key_type(found), fp); - 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)); -} |
