X-Git-Url: http://andersk.mit.edu/gitweb/openssh.git/blobdiff_plain/f11fe301db707c84444c626beaa73b2adc1207ac..7caca6d44d365220a637081df8cce38c5d26c588:/sshconnect.c diff --git a/sshconnect.c b/sshconnect.c index 32e57296..40d22800 100644 --- a/sshconnect.c +++ b/sshconnect.c @@ -13,7 +13,7 @@ */ #include "includes.h" -RCSID("$OpenBSD: sshconnect.c,v 1.127 2002/06/27 08:49:44 markus Exp $"); +RCSID("$OpenBSD: sshconnect.c,v 1.147 2003/06/29 12:44:38 markus Exp $"); #include @@ -33,29 +33,29 @@ RCSID("$OpenBSD: sshconnect.c,v 1.127 2002/06/27 08:49:44 markus Exp $"); #include "misc.h" #include "readpass.h" +#ifdef DNS +#include "dns.h" +#endif + char *client_version_string = NULL; char *server_version_string = NULL; +#ifdef DNS +int verified_host_key_dns = 0; +#endif + /* 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 const char * -sockaddr_ntop(struct sockaddr *sa, socklen_t salen) -{ - static char addrbuf[NI_MAXHOST]; - - if (getnameinfo(sa, salen, addrbuf, sizeof(addrbuf), NULL, 0, - NI_NUMERICHOST) != 0) - fatal("sockaddr_ntop: getnameinfo NI_NUMERICHOST failed"); - return addrbuf; -} +static int show_other_keys(const char *, Key *); /* * Connect to the given ssh server using a proxy command. @@ -73,9 +73,16 @@ ssh_proxy_connect(const char *host, u_short port, const char *proxy_command) /* 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. */ + /* + * 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) + */ buffer_init(&command); + buffer_append(&command, "exec ", 5); + for (cp = proxy_command; *cp; cp++) { if (cp[0] == '%' && cp[1] == '%') { buffer_append(&command, "%", 1); @@ -143,6 +150,8 @@ 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]); @@ -162,7 +171,7 @@ 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; @@ -174,15 +183,16 @@ 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); + sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol); if (sock < 0) error("socket: %.100s", strerror(errno)); @@ -191,8 +201,9 @@ ssh_create_socket(int privileged, int family) 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) { @@ -211,6 +222,73 @@ ssh_create_socket(int privileged, int family) 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)); + + if (fcntl(sockfd, F_SETFL, O_NONBLOCK) < 0) + return (-1); + + rc = connect(sockfd, serv_addr, addrlen); + if (rc == 0) + 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; + 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. @@ -238,7 +316,6 @@ ssh_connect(const char *host, struct sockaddr_storage * hostaddr, int sock = -1, attempt; char ntop[NI_MAXHOST], strport[NI_MAXSERV]; struct addrinfo hints, *ai, *aitop; - struct linger linger; struct servent *sp; /* * Did we get only other errors than "Connection refused" (which @@ -247,7 +324,7 @@ ssh_connect(const char *host, struct sockaddr_storage * hostaddr, */ 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) { @@ -295,21 +372,21 @@ 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, + options.connection_timeout) >= 0) { /* Successful connection. */ memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen); break; } else { if (errno == ECONNREFUSED) full_failure = 0; - log("ssh: connect to address %s port %s: %s", - sockaddr_ntop(ai->ai_addr, ai->ai_addrlen), - strport, strerror(errno)); + 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 @@ -332,20 +409,14 @@ ssh_connect(const char *host, struct sockaddr_storage * hostaddr, freeaddrinfo(aitop); /* Return failure if we didn't get a successful connection. */ - if (attempt >= connection_attempts) + if (attempt >= connection_attempts) { + logit("ssh: connect to host %s port %s: %s", + host, strport, strerror(errno)); return full_failure ? ECONNABORTED : ECONNREFUSED; + } debug("Connection established."); - /* - * Set socket options. We would like the socket to disappear as soon - * as it has been closed for whatever reason. - */ - /* setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */ - linger.l_onoff = 1; - linger.l_linger = 5; - setsockopt(sock, SOL_SOCKET, SO_LINGER, (void *)&linger, sizeof(linger)); - /* Set keepalives if requested. */ if (options.keepalives && setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on, @@ -428,7 +499,7 @@ 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; } } @@ -452,7 +523,7 @@ ssh_exchange_identification(void) 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); @@ -619,16 +690,16 @@ 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 " + 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); } @@ -647,14 +718,36 @@ 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) { + 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'; +#ifdef DNS + if (options.verify_host_key_dns) { + if (verified_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"); + } +#endif snprintf(msg, sizeof(msg), "The authenticity of host '%.200s (%s)' can't be " - "established.\n" - "%s key fingerprint is %s.\n" + "established%s\n" + "%s key fingerprint is %s.\n%s" "Are you sure you want to continue connecting " - "(yes/no)? ", host, ip, type, fp); + "(yes/no)? ", + host, ip, msg1, type, fp, msg2); xfree(fp); if (!confirm(msg)) goto fail; @@ -670,10 +763,10 @@ check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key, * 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: @@ -724,7 +817,7 @@ 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 + * the connection but without MITM-able authentication or * agent forwarding. */ if (options.password_authentication) { @@ -732,6 +825,17 @@ check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key, "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."); @@ -757,6 +861,9 @@ check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key, * accept the authentication. */ break; + case HOST_FOUND: + fatal("internal error"); + break; } if (options.check_host_ip && host_status != HOST_CHANGED && @@ -773,7 +880,7 @@ 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) { @@ -782,7 +889,7 @@ check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key, if (!confirm(msg)) goto fail; } else { - log(msg); + logit("%s", msg); } } @@ -794,11 +901,33 @@ fail: 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; +#ifdef DNS + if (options.verify_host_key_dns) { + switch(verify_host_key_dns(host, hostaddr, host_key)) { + case DNS_VERIFY_OK: +#ifdef DNSSEC + return 0; +#else + verified_host_key_dns = 1; + break; +#endif + case DNS_VERIFY_FAILED: + return -1; + case DNS_VERIFY_ERROR: + break; + default: + debug3("bad return value from verify_host_key_dns"); + break; + } + } +#endif /* DNS */ + /* 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) { @@ -868,3 +997,58 @@ ssh_put_password(char *password) 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); +}