=================================================================== RCS file: /cvsrepo/anoncvs/cvs/src/usr.bin/ssh/sshconnect.c,v retrieving revision 1.137 retrieving revision 1.137.2.2 diff -u -r1.137 -r1.137.2.2 --- src/usr.bin/ssh/sshconnect.c 2002/11/21 23:03:51 1.137 +++ src/usr.bin/ssh/sshconnect.c 2004/03/04 18:18:17 1.137.2.2 @@ -13,7 +13,7 @@ */ #include "includes.h" -RCSID("$OpenBSD: sshconnect.c,v 1.137 2002/11/21 23:03:51 deraadt Exp $"); +RCSID("$OpenBSD: sshconnect.c,v 1.137.2.2 2004/03/04 18:18:17 brad Exp $"); #include @@ -33,9 +33,13 @@ #include "misc.h" #include "readpass.h" +#include "dns.h" + char *client_version_string = NULL; char *server_version_string = NULL; +int matching_host_key_dns = 0; + /* import */ extern Options options; extern char *__progname; @@ -44,6 +48,7 @@ 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. @@ -65,7 +70,7 @@ * 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 + * Use "exec" to avoid "sh -c" processes on some platforms * (e.g. Solaris) */ buffer_init(&command); @@ -159,7 +164,7 @@ * 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; @@ -171,15 +176,16 @@ 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); + sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol); if (sock < 0) error("socket: %.100s", strerror(errno)); @@ -188,8 +194,9 @@ 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); if (gaierr) { @@ -208,6 +215,75 @@ 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 fdsetsz, 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); + + fdsetsz = howmany(sockfd + 1, NFDBITS) * sizeof(fd_mask); + fdset = (fd_set *)xmalloc(fdsetsz); + + memset(fdset, 0, fdsetsz); + 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. @@ -291,12 +367,13 @@ 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, + options.connection_timeout) >= 0) { /* Successful connection. */ memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen); break; @@ -328,15 +405,15 @@ /* Return failure if we didn't get a successful connection. */ if (attempt >= connection_attempts) { - log("ssh: connect to host %s port %s: %s", + logit("ssh: connect to host %s port %s: %s", host, strport, strerror(errno)); return full_failure ? ECONNABORTED : ECONNREFUSED; } debug("Connection established."); - /* Set keepalives if requested. */ - if (options.keepalives && + /* 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)); @@ -417,7 +494,7 @@ 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; } } @@ -441,7 +518,7 @@ compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1, compat20 ? PROTOCOL_MINOR_2 : minor1, SSH_VERSION); - if (atomicio(write, connection_out, buf, strlen(buf)) != strlen(buf)) + if (atomicio(vwrite, connection_out, buf, strlen(buf)) != strlen(buf)) fatal("write: %.100s", strerror(errno)); client_version_string = xstrdup(buf); chop(client_version_string); @@ -483,7 +560,7 @@ int readonly, const char *user_hostfile, const char *system_hostfile) { Key *file_key; - char *type = key_type(host_key); + const char *type = key_type(host_key); char *ip = NULL; char hostline[1000], *hostp, *fp; HostStatus host_status; @@ -491,7 +568,7 @@ int local = 0, host_ip_differ = 0; char ntop[NI_MAXHOST]; char msg[1024]; - int len, host_line, ip_line, has_keys; + int len, host_line, ip_line; const char *host_file = NULL, *ip_file = NULL; /* @@ -604,16 +681,16 @@ 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 " + 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); } @@ -632,19 +709,34 @@ "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); + 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.\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, msg2); xfree(fp); if (!confirm(msg)) goto fail; @@ -660,10 +752,10 @@ * 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 " + 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: @@ -687,20 +779,10 @@ 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 @@ -714,7 +796,7 @@ /* * If strict host key checking has not been requested, allow - * the connection but without password authentication or + * the connection but without MITM-able authentication or * agent forwarding. */ if (options.password_authentication) { @@ -722,6 +804,17 @@ "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."); @@ -766,7 +859,7 @@ 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) { @@ -775,7 +868,7 @@ if (!confirm(msg)) goto fail; } else { - log(msg); + logit("%s", msg); } } @@ -787,11 +880,33 @@ 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) { @@ -873,7 +988,7 @@ 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" + logit("WARNING: %s key found for host %s\n" "in %s:%d\n" "%s key fingerprint %s.", key_type(found), host, file, line, @@ -915,4 +1030,25 @@ 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); }