Edit
IABSD.fr/src/usr.bin/ssh/sshconnect.c
dtucker
- usr.bin/ssh/sshconnect.c
-
/* $OpenBSD: sshconnect.c,v 1.382 2026/02/16 00:45:41 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 <sys/types.h> #include <sys/wait.h> #include <sys/socket.h> #include <net/if.h> #include <netinet/in.h> #include <errno.h> #include <fcntl.h> #include <limits.h> #include <netdb.h> #include <paths.h> #include <pwd.h> #include <poll.h> #include <signal.h> #include <stdio.h> #include <stdlib.h> #include <stdarg.h> #include <string.h> #include <unistd.h> #include <ifaddrs.h> #include "xmalloc.h" #include "hostfile.h" #include "ssh.h" #include "compat.h" #include "packet.h" #include "sshkey.h" #include "sshconnect.h" #include "log.h" #include "match.h" #include "misc.h" #include "readconf.h" #include "dns.h" #include "monitor_fdpass.h" #include "authfile.h" #include "ssherr.h" #include "authfd.h" #include "kex.h" struct sshkey *previous_host_key = NULL; static int matching_host_key_dns = 0; static pid_t proxy_command_pid = 0; /* import */ extern int debug_flag; extern Options options; extern char *__progname; static int show_other_keys(struct hostkeys *, struct sshkey *); static void warn_changed_key(struct sshkey *); /* Expand a proxy command */ static char * expand_proxy_command(const char *proxy_command, const char *user, const char *host, const char *host_arg, int port) { char *tmp, *ret, strport[NI_MAXSERV]; const char *keyalias = options.host_key_alias ? options.host_key_alias : host_arg; snprintf(strport, sizeof strport, "%d", port); xasprintf(&tmp, "exec %s", proxy_command); ret = percent_expand(tmp, "h", host, "k", keyalias, "n", host_arg, "p", strport, "r", options.user, (char *)NULL); free(tmp); return ret; } /* * Connect to the given ssh server using a proxy command that passes a * a connected fd back to us. */ static int ssh_proxy_fdpass_connect(struct ssh *ssh, const char *host, const char *host_arg, u_short port, const char *proxy_command) { char *command_string; int sp[2], sock; pid_t pid; char *shell; if ((shell = getenv("SHELL")) == NULL) shell = _PATH_BSHELL; if (socketpair(AF_UNIX, SOCK_STREAM, 0, sp) == -1) fatal("Could not create socketpair to communicate with " "proxy dialer: %.100s", strerror(errno)); command_string = expand_proxy_command(proxy_command, options.user, host, host_arg, port); debug("Executing proxy dialer command: %.500s", command_string); /* Fork and execute the proxy command. */ if ((pid = fork()) == 0) { char *argv[10]; close(sp[1]); /* Redirect stdin and stdout. */ if (sp[0] != 0) { if (dup2(sp[0], 0) == -1) perror("dup2 stdin"); } if (sp[0] != 1) { if (dup2(sp[0], 1) == -1) perror("dup2 stdout"); } if (sp[0] >= 2) close(sp[0]); /* * Stderr is left for non-ControlPersist connections is so * error messages may be printed on the user's terminal. */ if (!debug_flag && options.control_path != NULL && options.control_persist && stdfd_devnull(0, 0, 1) == -1) error_f("stdfd_devnull failed"); 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 == -1) fatal("fork failed: %.100s", strerror(errno)); close(sp[0]); free(command_string); if ((sock = mm_receive_fd(sp[1])) == -1) fatal("proxy dialer did not pass back a connection"); close(sp[1]); while (waitpid(pid, NULL, 0) == -1) if (errno != EINTR) fatal("Couldn't wait for child: %s", strerror(errno)); /* Set the connection file descriptors. */ if (ssh_packet_set_connection(ssh, sock, sock) == NULL) return -1; /* ssh_packet_set_connection logs error */ return 0; } /* * Connect to the given ssh server using a proxy command. */ static int ssh_proxy_connect(struct ssh *ssh, const char *host, const char *host_arg, u_short port, const char *proxy_command) { char *command_string; int pin[2], pout[2]; pid_t pid; char *shell; if ((shell = getenv("SHELL")) == NULL || *shell == '\0') shell = _PATH_BSHELL; /* Create pipes for communicating with the proxy. */ if (pipe(pin) == -1 || pipe(pout) == -1) fatal("Could not create pipes to communicate with the proxy: %.100s", strerror(errno)); command_string = expand_proxy_command(proxy_command, options.user, host, host_arg, port); debug("Executing proxy command: %.500s", command_string); /* Fork and execute the proxy command. */ if ((pid = fork()) == 0) { char *argv[10]; /* Redirect stdin and stdout. */ close(pin[1]); if (pin[0] != 0) { if (dup2(pin[0], 0) == -1) perror("dup2 stdin"); close(pin[0]); } close(pout[0]); if (dup2(pout[1], 1) == -1) perror("dup2 stdout"); /* Cannot be 1 because pin allocated two descriptors. */ close(pout[1]); /* * Stderr is left for non-ControlPersist connections is so * error messages may be printed on the user's terminal. */ if (!debug_flag && options.control_path != NULL && options.control_persist && stdfd_devnull(0, 0, 1) == -1) error_f("stdfd_devnull failed"); 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. */ ssh_signal(SIGPIPE, SIG_DFL); execv(argv[0], argv); perror(argv[0]); exit(1); } /* Parent. */ if (pid == -1) 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. */ free(command_string); /* Set the connection file descriptors. */ if (ssh_packet_set_connection(ssh, pout[0], pin[1]) == NULL) return -1; /* ssh_packet_set_connection logs error */ return 0; } void ssh_kill_proxy_command(void) { /* * Send SIGHUP to proxy command if used. We don't wait() in * case it hangs and instead rely on init to reap the child */ if (proxy_command_pid > 1) kill(proxy_command_pid, SIGHUP); } /* * Search a interface address list (returned from getifaddrs(3)) for an * address that matches the desired address family on the specified interface. * Returns 0 and fills in *resultp and *rlenp on success. Returns -1 on failure. */ static int check_ifaddrs(const char *ifname, int af, const struct ifaddrs *ifaddrs, struct sockaddr_storage *resultp, socklen_t *rlenp) { struct sockaddr_in6 *sa6; struct sockaddr_in *sa; struct in6_addr *v6addr; const struct ifaddrs *ifa; int allow_local; /* * Prefer addresses that are not loopback or linklocal, but use them * if nothing else matches. */ for (allow_local = 0; allow_local < 2; allow_local++) { for (ifa = ifaddrs; ifa != NULL; ifa = ifa->ifa_next) { if (ifa->ifa_addr == NULL || ifa->ifa_name == NULL || (ifa->ifa_flags & IFF_UP) == 0 || ifa->ifa_addr->sa_family != af || strcmp(ifa->ifa_name, options.bind_interface) != 0) continue; switch (ifa->ifa_addr->sa_family) { case AF_INET: sa = (struct sockaddr_in *)ifa->ifa_addr; if (!allow_local && sa->sin_addr.s_addr == htonl(INADDR_LOOPBACK)) continue; if (*rlenp < sizeof(struct sockaddr_in)) { error_f("v4 addr doesn't fit"); return -1; } *rlenp = sizeof(struct sockaddr_in); memcpy(resultp, sa, *rlenp); return 0; case AF_INET6: sa6 = (struct sockaddr_in6 *)ifa->ifa_addr; v6addr = &sa6->sin6_addr; if (!allow_local && (IN6_IS_ADDR_LINKLOCAL(v6addr) || IN6_IS_ADDR_LOOPBACK(v6addr))) continue; if (*rlenp < sizeof(struct sockaddr_in6)) { error_f("v6 addr doesn't fit"); return -1; } *rlenp = sizeof(struct sockaddr_in6); memcpy(resultp, sa6, *rlenp); return 0; } } } return -1; } /* * Creates a socket for use as the ssh connection. */ static int ssh_create_socket(struct addrinfo *ai) { int sock, r; struct sockaddr_storage bindaddr; socklen_t bindaddrlen = 0; struct addrinfo hints, *res = NULL; struct ifaddrs *ifaddrs = NULL; char ntop[NI_MAXHOST]; sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol); if (sock == -1) { error("socket: %s", strerror(errno)); return -1; } (void)fcntl(sock, F_SETFD, FD_CLOEXEC); /* Use interactive QOS (if specified) until authentication completed */ if (options.ip_qos_interactive != INT_MAX) set_sock_tos(sock, options.ip_qos_interactive); /* Bind the socket to an alternative local IP address */ if (options.bind_address == NULL && options.bind_interface == NULL) return sock; if (options.bind_address != NULL) { 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; if ((r = getaddrinfo(options.bind_address, NULL, &hints, &res)) != 0) { error("getaddrinfo: %s: %s", options.bind_address, ssh_gai_strerror(r)); goto fail; } if (res == NULL) { error("getaddrinfo: no addrs"); goto fail; } memcpy(&bindaddr, res->ai_addr, res->ai_addrlen); bindaddrlen = res->ai_addrlen; } else if (options.bind_interface != NULL) { if ((r = getifaddrs(&ifaddrs)) != 0) { error("getifaddrs: %s: %s", options.bind_interface, strerror(errno)); goto fail; } bindaddrlen = sizeof(bindaddr); if (check_ifaddrs(options.bind_interface, ai->ai_family, ifaddrs, &bindaddr, &bindaddrlen) != 0) { logit("getifaddrs: %s: no suitable addresses", options.bind_interface); goto fail; } } if ((r = getnameinfo((struct sockaddr *)&bindaddr, bindaddrlen, ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST)) != 0) { error_f("getnameinfo failed: %s", ssh_gai_strerror(r)); goto fail; } if (bind(sock, (struct sockaddr *)&bindaddr, bindaddrlen) != 0) { error("bind %s: %s", ntop, strerror(errno)); goto fail; } debug_f("bound to %s", ntop); /* success */ goto out; fail: close(sock); sock = -1; out: if (res != NULL) freeaddrinfo(res); if (ifaddrs != NULL) freeifaddrs(ifaddrs); return sock; } /* * 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. * 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. */ static int ssh_connect_direct(struct ssh *ssh, const char *host, struct addrinfo *aitop, struct sockaddr_storage *hostaddr, u_short port, int connection_attempts, int *timeout_ms, int want_keepalive) { int on = 1, saved_timeout_ms = *timeout_ms; int oerrno, sock = -1, attempt; char ntop[NI_MAXHOST], strport[NI_MAXSERV]; struct addrinfo *ai; debug3_f("entering"); memset(ntop, 0, sizeof(ntop)); memset(strport, 0, sizeof(strport)); 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) { errno = EAFNOSUPPORT; continue; } if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop), strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) { oerrno = errno; error_f("getnameinfo failed"); errno = oerrno; continue; } if (options.address_family != AF_UNSPEC && ai->ai_family != options.address_family) { debug2_f("skipping address [%s]:%s: " "wrong address family", ntop, strport); errno = EAFNOSUPPORT; continue; } debug("Connecting to %.200s [%.100s] port %s.", host, ntop, strport); /* Create a socket for connecting. */ sock = ssh_create_socket(ai); if (sock < 0) { /* Any error is already output */ errno = 0; continue; } *timeout_ms = saved_timeout_ms; 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 { oerrno = errno; debug("connect to address %s port %s: %s", ntop, strport, strerror(errno)); close(sock); sock = -1; errno = oerrno; } } if (sock != -1) break; /* Successful connection. */ } /* Return failure if we didn't get a successful connection. */ if (sock == -1) { error("ssh: connect to host %s port %s: %s", host, strport, errno == 0 ? "failure" : 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)) == -1) error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); /* Set the connection. */ if (ssh_packet_set_connection(ssh, sock, sock) == NULL) return -1; /* ssh_packet_set_connection logs error */ return 0; } int ssh_connect(struct ssh *ssh, const char *host, const char *host_arg, struct addrinfo *addrs, struct sockaddr_storage *hostaddr, u_short port, int connection_attempts, int *timeout_ms, int want_keepalive) { int in, out; if (options.proxy_command == NULL) { return ssh_connect_direct(ssh, host, addrs, hostaddr, port, connection_attempts, timeout_ms, want_keepalive); } else if (strcmp(options.proxy_command, "-") == 0) { if ((in = dup(STDIN_FILENO)) == -1 || (out = dup(STDOUT_FILENO)) == -1) { if (in >= 0) close(in); error_f("dup() in/out failed"); return -1; /* ssh_packet_set_connection logs error */ } if ((ssh_packet_set_connection(ssh, in, out)) == NULL) return -1; /* ssh_packet_set_connection logs error */ return 0; } else if (options.proxy_use_fdpass) { return ssh_proxy_fdpass_connect(ssh, host, host_arg, port, options.proxy_command); } return ssh_proxy_connect(ssh, host, host_arg, port, options.proxy_command); } /* defaults to 'no' */ static int confirm(const char *prompt, const char *fingerprint) { const char *msg, *again = "Please type 'yes' or 'no': "; const char *again_fp = "Please type 'yes', 'no' or the fingerprint: "; char *p, *cp; int ret = -1; if (options.batch_mode) return 0; for (msg = prompt;;msg = fingerprint ? again_fp : again) { cp = p = read_passphrase(msg, RP_ECHO); if (p == NULL) return 0; p += strspn(p, " \t"); /* skip leading whitespace */ p[strcspn(p, " \t\n")] = '\0'; /* remove trailing whitespace */ if (p[0] == '\0' || strcasecmp(p, "no") == 0) ret = 0; else if (strcasecmp(p, "yes") == 0 || (fingerprint != NULL && strcmp(p, fingerprint) == 0)) ret = 1; free(cp); if (ret != -1) return ret; } } static int sockaddr_is_local(struct sockaddr *hostaddr) { switch (hostaddr->sa_family) { case AF_INET: return (ntohl(((struct sockaddr_in *)hostaddr)-> sin_addr.s_addr) >> 24) == IN_LOOPBACKNET; case AF_INET6: return IN6_IS_ADDR_LOOPBACK( &(((struct sockaddr_in6 *)hostaddr)->sin6_addr)); default: return 0; } } /* * Prepare the hostname and ip address strings that are used to lookup * host keys in known_hosts files. These may have a port number appended. */ void get_hostfile_hostname_ipaddr(char *hostname, struct sockaddr *hostaddr, u_short port, char **hostfile_hostname, char **hostfile_ipaddr) { char ntop[NI_MAXHOST]; /* * We don't have the remote ip-address for connections * using a proxy command */ if (hostfile_ipaddr != NULL) { if (options.proxy_command == NULL) { if (getnameinfo(hostaddr, hostaddr->sa_len, ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST) != 0) fatal_f("getnameinfo failed"); *hostfile_ipaddr = put_host_port(ntop, port); } else { *hostfile_ipaddr = xstrdup("<no hostip for proxy " "command>"); } } /* * 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 (hostfile_hostname != NULL) { if (options.host_key_alias != NULL) { *hostfile_hostname = xstrdup(options.host_key_alias); debug("using hostkeyalias: %s", *hostfile_hostname); } else { *hostfile_hostname = put_host_port(hostname, port); } } } /* returns non-zero if path appears in hostfiles, or 0 if not. */ static int path_in_hostfiles(const char *path, char **hostfiles, u_int num_hostfiles) { u_int i; for (i = 0; i < num_hostfiles; i++) { if (strcmp(path, hostfiles[i]) == 0) return 1; } return 0; } struct find_by_key_ctx { const char *host, *ip; const struct sshkey *key; char **names; u_int nnames; }; /* Try to replace home directory prefix (per $HOME) with a ~/ sequence */ static char * try_tilde_unexpand(const char *path) { char *home, *ret = NULL; size_t l; if (*path != '/') return xstrdup(path); if ((home = getenv("HOME")) == NULL || (l = strlen(home)) == 0) return xstrdup(path); if (strncmp(path, home, l) != 0) return xstrdup(path); /* * ensure we have matched on a path boundary: either the $HOME that * we just compared ends with a '/' or the next character of the path * must be a '/'. */ if (home[l - 1] != '/' && path[l] != '/') return xstrdup(path); if (path[l] == '/') l++; xasprintf(&ret, "~/%s", path + l); return ret; } /* * Returns non-zero if the key is accepted by HostkeyAlgorithms. * Made slightly less trivial by the multiple RSA signature algorithm names. */ int hostkey_accepted_by_hostkeyalgs(const struct sshkey *key) { const char *ktype = sshkey_ssh_name(key); const char *hostkeyalgs = options.hostkeyalgorithms; if (key->type == KEY_UNSPEC) return 0; if (key->type == KEY_RSA && (match_pattern_list("rsa-sha2-256", hostkeyalgs, 0) == 1 || match_pattern_list("rsa-sha2-512", hostkeyalgs, 0) == 1)) return 1; if (key->type == KEY_RSA_CERT && (match_pattern_list("rsa-sha2-512-cert-v01@openssh.com", hostkeyalgs, 0) == 1 || match_pattern_list("rsa-sha2-256-cert-v01@openssh.com", hostkeyalgs, 0) == 1)) return 1; return match_pattern_list(ktype, hostkeyalgs, 0) == 1; } static int hostkeys_find_by_key_cb(struct hostkey_foreach_line *l, void *_ctx) { struct find_by_key_ctx *ctx = (struct find_by_key_ctx *)_ctx; char *path; /* we are looking for keys with names that *do not* match */ if ((l->match & HKF_MATCH_HOST) != 0) return 0; /* not interested in marker lines */ if (l->marker != MRK_NONE) return 0; /* we are only interested in exact key matches */ if (l->key == NULL || !sshkey_equal(ctx->key, l->key)) return 0; path = try_tilde_unexpand(l->path); debug_f("found matching key in %s:%lu", path, l->linenum); ctx->names = xrecallocarray(ctx->names, ctx->nnames, ctx->nnames + 1, sizeof(*ctx->names)); xasprintf(&ctx->names[ctx->nnames], "%s:%lu: %s", path, l->linenum, strncmp(l->hosts, HASH_MAGIC, strlen(HASH_MAGIC)) == 0 ? "[hashed name]" : l->hosts); ctx->nnames++; free(path); return 0; } static int hostkeys_find_by_key_hostfile(const char *file, const char *which, struct find_by_key_ctx *ctx) { int r; debug3_f("trying %s hostfile \"%s\"", which, file); if ((r = hostkeys_foreach(file, hostkeys_find_by_key_cb, ctx, ctx->host, ctx->ip, HKF_WANT_PARSE_KEY, 0)) != 0) { if (r == SSH_ERR_SYSTEM_ERROR && errno == ENOENT) { debug_f("hostkeys file %s does not exist", file); return 0; } error_fr(r, "hostkeys_foreach failed for %s", file); return r; } return 0; } /* * Find 'key' in known hosts file(s) that do not match host/ip. * Used to display also-known-as information for previously-unseen hostkeys. */ static void hostkeys_find_by_key(const char *host, const char *ip, const struct sshkey *key, char **user_hostfiles, u_int num_user_hostfiles, char **system_hostfiles, u_int num_system_hostfiles, char ***names, u_int *nnames) { struct find_by_key_ctx ctx = {NULL, NULL, NULL, NULL, 0}; u_int i; *names = NULL; *nnames = 0; if (key == NULL || sshkey_is_cert(key)) return; ctx.host = host; ctx.ip = ip; ctx.key = key; for (i = 0; i < num_user_hostfiles; i++) { if (hostkeys_find_by_key_hostfile(user_hostfiles[i], "user", &ctx) != 0) goto fail; } for (i = 0; i < num_system_hostfiles; i++) { if (hostkeys_find_by_key_hostfile(system_hostfiles[i], "system", &ctx) != 0) goto fail; } /* success */ *names = ctx.names; *nnames = ctx.nnames; ctx.names = NULL; ctx.nnames = 0; return; fail: for (i = 0; i < ctx.nnames; i++) free(ctx.names[i]); free(ctx.names); } #define MAX_OTHER_NAMES 8 /* Maximum number of names to list */ static char * other_hostkeys_message(const char *host, const char *ip, const struct sshkey *key, char **user_hostfiles, u_int num_user_hostfiles, char **system_hostfiles, u_int num_system_hostfiles) { char *ret = NULL, **othernames = NULL; u_int i, n, num_othernames = 0; hostkeys_find_by_key(host, ip, key, user_hostfiles, num_user_hostfiles, system_hostfiles, num_system_hostfiles, &othernames, &num_othernames); if (num_othernames == 0) return xstrdup("This key is not known by any other names."); xasprintf(&ret, "This host key is known by the following other " "names/addresses:"); n = num_othernames; if (n > MAX_OTHER_NAMES) n = MAX_OTHER_NAMES; for (i = 0; i < n; i++) { xextendf(&ret, "\n", " %s", othernames[i]); } if (n < num_othernames) { xextendf(&ret, "\n", " (%d additional names omitted)", num_othernames - n); } for (i = 0; i < num_othernames; i++) free(othernames[i]); free(othernames); return ret; } void load_hostkeys_command(struct hostkeys *hostkeys, const char *command_template, const char *invocation, const struct ssh_conn_info *cinfo, const struct sshkey *host_key, const char *hostfile_hostname) { int r, i, ac = 0; char *key_fp = NULL, *keytext = NULL, *tmp; char *command = NULL, *tag = NULL, **av = NULL; FILE *f = NULL; pid_t pid; void (*osigchld)(int); xasprintf(&tag, "KnownHostsCommand-%s", invocation); if (host_key != NULL) { if ((key_fp = sshkey_fingerprint(host_key, options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) fatal_f("sshkey_fingerprint failed"); if ((r = sshkey_to_base64(host_key, &keytext)) != 0) fatal_fr(r, "sshkey_to_base64 failed"); } /* * NB. all returns later this function should go via "out" to * ensure the original SIGCHLD handler is restored properly. */ osigchld = ssh_signal(SIGCHLD, SIG_DFL); /* Turn the command into an argument vector */ if (argv_split(command_template, &ac, &av, 0) != 0) { error("%s \"%s\" contains invalid quotes", tag, command_template); goto out; } if (ac == 0) { error("%s \"%s\" yielded no arguments", tag, command_template); goto out; } for (i = 1; i < ac; i++) { tmp = percent_dollar_expand(av[i], DEFAULT_CLIENT_PERCENT_EXPAND_ARGS(cinfo), "H", hostfile_hostname, "I", invocation, "t", host_key == NULL ? "NONE" : sshkey_ssh_name(host_key), "f", key_fp == NULL ? "NONE" : key_fp, "K", keytext == NULL ? "NONE" : keytext, (char *)NULL); if (tmp == NULL) fatal_f("percent_expand failed"); free(av[i]); av[i] = tmp; } /* Prepare a printable command for logs, etc. */ command = argv_assemble(ac, av); if ((pid = subprocess(tag, command, ac, av, &f, SSH_SUBPROCESS_STDOUT_CAPTURE|SSH_SUBPROCESS_UNSAFE_PATH| SSH_SUBPROCESS_PRESERVE_ENV, NULL, NULL, NULL)) == 0) goto out; load_hostkeys_file(hostkeys, hostfile_hostname, tag, f, 1); if (exited_cleanly(pid, tag, command, 0) != 0) fatal("KnownHostsCommand failed"); out: if (f != NULL) fclose(f); ssh_signal(SIGCHLD, osigchld); for (i = 0; i < ac; i++) free(av[i]); free(av); free(tag); free(command); free(key_fp); free(keytext); } /* * check whether the supplied host key is valid, return -1 if the key * is not valid. user_hostfile[0] will not be updated if 'readonly' is true. */ #define RDRW 0 #define RDONLY 1 #define ROQUIET 2 static int check_host_key(char *hostname, const struct ssh_conn_info *cinfo, struct sockaddr *hostaddr, u_short port, struct sshkey *host_key, int readonly, int clobber_port, char **user_hostfiles, u_int num_user_hostfiles, char **system_hostfiles, u_int num_system_hostfiles, const char *hostfile_command) { HostStatus host_status = -1, ip_status = -1; struct sshkey *raw_key = NULL; char *ip = NULL, *host = NULL; char hostline[1000], *hostp, *fp, *ra; char msg[1024]; const char *type, *fail_reason = NULL; const struct hostkey_entry *host_found = NULL, *ip_found = NULL; int len, cancelled_forwarding = 0, confirmed; int local = sockaddr_is_local(hostaddr); int r, want_cert = sshkey_is_cert(host_key), host_ip_differ = 0; int hostkey_trusted = 0; /* Known or explicitly accepted by user */ struct hostkeys *host_hostkeys, *ip_hostkeys; u_int i; /* * 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. */ if (options.no_host_authentication_for_localhost == 1 && local && options.host_key_alias == NULL) { debug("Forcing accepting of host key for " "loopback/localhost."); options.update_hostkeys = 0; return 0; } /* * Don't ever try to write an invalid name to a known hosts file. * Note: do this before get_hostfile_hostname_ipaddr() to catch * '[' or ']' in the name before they are added. */ if (strcspn(hostname, "@?*#[]|'\'\"\\") != strlen(hostname)) { debug_f("invalid hostname \"%s\"; will not record: %s", hostname, fail_reason); readonly = RDONLY; } /* * Prepare the hostname and address strings used for hostkey lookup. * In some cases, these will have a port number appended. */ get_hostfile_hostname_ipaddr(hostname, hostaddr, clobber_port ? 0 : port, &host, &ip); /* * 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; host_hostkeys = init_hostkeys(); for (i = 0; i < num_user_hostfiles; i++) load_hostkeys(host_hostkeys, host, user_hostfiles[i], 0); for (i = 0; i < num_system_hostfiles; i++) load_hostkeys(host_hostkeys, host, system_hostfiles[i], 0); if (hostfile_command != NULL && !clobber_port) { load_hostkeys_command(host_hostkeys, hostfile_command, "HOSTNAME", cinfo, host_key, host); } ip_hostkeys = NULL; if (!want_cert && options.check_host_ip) { ip_hostkeys = init_hostkeys(); for (i = 0; i < num_user_hostfiles; i++) load_hostkeys(ip_hostkeys, ip, user_hostfiles[i], 0); for (i = 0; i < num_system_hostfiles; i++) load_hostkeys(ip_hostkeys, ip, system_hostfiles[i], 0); if (hostfile_command != NULL && !clobber_port) { load_hostkeys_command(ip_hostkeys, hostfile_command, "ADDRESS", cinfo, host_key, ip); } } retry: if (!hostkey_accepted_by_hostkeyalgs(host_key)) { error("host key %s not permitted by HostkeyAlgorithms", sshkey_ssh_name(host_key)); goto fail; } /* Reload these as they may have changed on cert->key downgrade */ want_cert = sshkey_is_cert(host_key); type = sshkey_type(host_key); /* * Check if the host key is present in the user's list of known * hosts or in the systemwide list. */ host_status = check_key_in_hostkeys(host_hostkeys, host_key, &host_found); /* * If there are no hostfiles, or if the hostkey was found via * KnownHostsCommand, then don't try to touch the disk. */ if (!readonly && (num_user_hostfiles == 0 || (host_found != NULL && host_found->note != 0))) readonly = RDONLY; /* * Also perform check for the ip address, skip the check if we are * localhost, looking for a certificate, or the hostname was an ip * address to begin with. */ if (!want_cert && ip_hostkeys != NULL) { ip_status = check_key_in_hostkeys(ip_hostkeys, host_key, &ip_found); if (host_status == HOST_CHANGED && (ip_status != HOST_CHANGED || (ip_found != NULL && !sshkey_equal(ip_found->key, host_found->key)))) host_ip_differ = 1; } else ip_status = host_status; switch (host_status) { case HOST_OK: /* The host is known and the key matches. */ debug("Host '%.200s' is known and matches the %s host %s.", host, type, want_cert ? "certificate" : "key"); debug("Found %s in %s:%lu", want_cert ? "CA key" : "key", host_found->file, host_found->line); if (want_cert) { if (sshkey_cert_check_host(host_key, options.host_key_alias == NULL ? hostname : options.host_key_alias, options.ca_sign_algorithms, &fail_reason) != 0) { error("%s", fail_reason); goto fail; } /* * Do not attempt hostkey update if a certificate was * successfully matched. */ if (options.update_hostkeys != 0) { options.update_hostkeys = 0; debug3_f("certificate host key in use; " "disabling UpdateHostkeys"); } } /* Turn off UpdateHostkeys if key was in system known_hosts */ if (options.update_hostkeys != 0 && (path_in_hostfiles(host_found->file, system_hostfiles, num_system_hostfiles) || (ip_status == HOST_OK && ip_found != NULL && path_in_hostfiles(ip_found->file, system_hostfiles, num_system_hostfiles)))) { options.update_hostkeys = 0; debug3_f("host key found in GlobalKnownHostsFile; " "disabling UpdateHostkeys"); } if (options.update_hostkeys != 0 && host_found->note) { options.update_hostkeys = 0; debug3_f("host key found via KnownHostsCommand; " "disabling UpdateHostkeys"); } if (options.check_host_ip && ip_status == HOST_NEW) { if (readonly || want_cert) logit("%s host key for IP address " "'%.128s' not in list of known hosts.", type, ip); else if (!add_host_to_hostfile(user_hostfiles[0], 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 (%.500s).", type, ip, user_hostfiles[0]); else logit("Warning: Permanently added the %s host " "key for IP address '%.128s' to the list " "of known hosts.", type, ip); } else if (options.visual_host_key) { fp = sshkey_fingerprint(host_key, options.fingerprint_hash, SSH_FP_DEFAULT); ra = sshkey_fingerprint(host_key, options.fingerprint_hash, SSH_FP_RANDOMART); if (fp == NULL || ra == NULL) fatal_f("sshkey_fingerprint failed"); logit("Host key fingerprint is: %s\n%s", fp, ra); free(ra); free(fp); } hostkey_trusted = 1; break; case HOST_NEW: if (options.host_key_alias == NULL && port != 0 && port != SSH_DEFAULT_PORT && !clobber_port) { debug("checking without port identifier"); if (check_host_key(hostname, cinfo, hostaddr, 0, host_key, ROQUIET, 1, user_hostfiles, num_user_hostfiles, system_hostfiles, num_system_hostfiles, hostfile_command) == 0) { debug("found matching key w/out port"); break; } } if (readonly || want_cert) goto fail; /* The host is new. */ if (options.strict_host_key_checking == SSH_STRICT_HOSTKEY_YES) { /* * 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 == SSH_STRICT_HOSTKEY_ASK) { char *msg1 = NULL, *msg2 = NULL; xasprintf(&msg1, "The authenticity of host " "'%.200s (%s)' can't be established", host, ip); if (show_other_keys(host_hostkeys, host_key)) { xextendf(&msg1, "\n", "but keys of different " "type are already known for this host."); } else xextendf(&msg1, "", "."); fp = sshkey_fingerprint(host_key, options.fingerprint_hash, SSH_FP_DEFAULT); ra = sshkey_fingerprint(host_key, options.fingerprint_hash, SSH_FP_RANDOMART); if (fp == NULL || ra == NULL) fatal_f("sshkey_fingerprint failed"); xextendf(&msg1, "\n", "%s key fingerprint is: %s", type, fp); if (options.visual_host_key) xextendf(&msg1, "\n", "%s", ra); if (options.verify_host_key_dns) { xextendf(&msg1, "\n", "%s host key fingerprint found in DNS.", matching_host_key_dns ? "Matching" : "No matching"); } /* msg2 informs for other names matching this key */ if ((msg2 = other_hostkeys_message(host, ip, host_key, user_hostfiles, num_user_hostfiles, system_hostfiles, num_system_hostfiles)) != NULL) xextendf(&msg1, "\n", "%s", msg2); xextendf(&msg1, "\n", "Are you sure you want to continue connecting " "(yes/no/[fingerprint])? "); confirmed = confirm(msg1, fp); free(ra); free(fp); free(msg1); free(msg2); if (!confirmed) goto fail; hostkey_trusted = 1; /* user explicitly confirmed */ } /* * If in "new" or "off" 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_hostfiles[0], host, host_key, options.hash_known_hosts) && add_host_to_hostfile(user_hostfiles[0], ip, host_key, options.hash_known_hosts); } else { /* Add unhashed "host,ip" */ r = add_host_to_hostfile(user_hostfiles[0], hostline, host_key, options.hash_known_hosts); } } else { r = add_host_to_hostfile(user_hostfiles[0], 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_hostfiles[0]); else logit("Warning: Permanently added '%.200s' (%s) to the " "list of known hosts.", hostp, type); break; case HOST_REVOKED: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); error("@ WARNING: REVOKED HOST KEY DETECTED! @"); error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); error("The %s host key for %s is marked as revoked.", type, host); error("This could mean that a stolen key is being used to"); error("impersonate this host."); /* * 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 != SSH_STRICT_HOSTKEY_OFF) { error("%s host key for %.200s was revoked and you have " "requested strict checking.", type, host); goto fail; } goto continue_unsafe; case HOST_CHANGED: if (want_cert) { /* * This is only a debug() since it is valid to have * CAs with wildcard DNS matches that don't match * all hosts that one might visit. */ debug("Host certificate authority does not " "match %s in %s:%lu", CA_MARKER, host_found->file, host_found->line); goto fail; } 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 corresponding IP address %s", ip); error("%s. This could either mean that", key_msg); error("DNS SPOOFING is happening or the IP address for the host"); error("and its host key have changed at the same time."); if (ip_status != HOST_NEW) error("Offending key for IP in %s:%lu", ip_found->file, ip_found->line); } /* The host key has changed. */ warn_changed_key(host_key); if (num_user_hostfiles > 0 || num_system_hostfiles > 0) { error("Add correct host key in %.100s to get rid " "of this message.", num_user_hostfiles > 0 ? user_hostfiles[0] : system_hostfiles[0]); } error("Offending %s key in %s:%lu", sshkey_type(host_found->key), host_found->file, host_found->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 != SSH_STRICT_HOSTKEY_OFF) { error("Host key for %.200s has changed and you have " "requested strict checking.", host); goto fail; } continue_unsafe: /* * 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; cancelled_forwarding = 1; } if (options.kbd_interactive_authentication) { error("Keyboard-interactive authentication is disabled" " to avoid man-in-the-middle attacks."); options.kbd_interactive_authentication = 0; cancelled_forwarding = 1; } if (options.forward_agent) { error("Agent forwarding is disabled to avoid " "man-in-the-middle attacks."); options.forward_agent = 0; cancelled_forwarding = 1; } if (options.forward_x11) { error("X11 forwarding is disabled to avoid " "man-in-the-middle attacks."); options.forward_x11 = 0; cancelled_forwarding = 1; } if (options.num_local_forwards > 0 || options.num_remote_forwards > 0) { error("Port forwarding is disabled to avoid " "man-in-the-middle attacks."); options.num_local_forwards = options.num_remote_forwards = 0; cancelled_forwarding = 1; } if (options.tun_open != SSH_TUNMODE_NO) { error("Tunnel forwarding is disabled to avoid " "man-in-the-middle attacks."); options.tun_open = SSH_TUNMODE_NO; cancelled_forwarding = 1; } if (options.update_hostkeys != 0) { error("UpdateHostkeys is disabled because the host " "key is not trusted."); options.update_hostkeys = 0; } if (options.exit_on_forward_failure && cancelled_forwarding) fatal("Error: forwarding disabled due to host key " "check failure"); /* * XXX Should permit the user to change to use the new id. * This could be done by converting the host key to an * identifying sentence, tell that the host identifies itself * by that sentence, and ask the user if they wish 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:%lu", type, host, ip, ip_found->file, ip_found->line); if (host_status == HOST_OK) { len = strlen(msg); snprintf(msg + len, sizeof(msg) - len, "\nMatching host key in %s:%lu", host_found->file, host_found->line); } if (options.strict_host_key_checking == SSH_STRICT_HOSTKEY_ASK) { strlcat(msg, "\nAre you sure you want " "to continue connecting (yes/no)? ", sizeof(msg)); if (!confirm(msg, NULL)) goto fail; } else if (options.strict_host_key_checking != SSH_STRICT_HOSTKEY_OFF) { logit("%s", msg); error("Exiting, you have requested strict checking."); goto fail; } else { logit("%s", msg); } } if (!hostkey_trusted && options.update_hostkeys) { debug_f("hostkey not known or explicitly trusted: " "disabling UpdateHostkeys"); options.update_hostkeys = 0; } sshkey_free(raw_key); free(ip); free(host); if (host_hostkeys != NULL) free_hostkeys(host_hostkeys); if (ip_hostkeys != NULL) free_hostkeys(ip_hostkeys); return 0; fail: if (want_cert && host_status != HOST_REVOKED) { /* * No matching certificate. Downgrade cert to raw key and * search normally. */ debug("No matching CA found. Retry with plain key"); if ((r = sshkey_from_private(host_key, &raw_key)) != 0) fatal_fr(r, "decode key"); if ((r = sshkey_drop_cert(raw_key)) != 0) fatal_r(r, "Couldn't drop certificate"); host_key = raw_key; goto retry; } sshkey_free(raw_key); free(ip); free(host); if (host_hostkeys != NULL) free_hostkeys(host_hostkeys); if (ip_hostkeys != NULL) free_hostkeys(ip_hostkeys); return -1; } /* returns 0 if key verifies or -1 if key does NOT verify */ int verify_host_key(char *host, struct sockaddr *hostaddr, struct sshkey *host_key, const struct ssh_conn_info *cinfo) { u_int i; int r = -1, flags = 0; char valid[64], *fp = NULL, *cafp = NULL; struct sshkey *plain = NULL; if ((fp = sshkey_fingerprint(host_key, options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) { error_fr(r, "fingerprint host key"); r = -1; goto out; } if (sshkey_is_cert(host_key)) { if ((cafp = sshkey_fingerprint(host_key->cert->signature_key, options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) { error_fr(r, "fingerprint CA key"); r = -1; goto out; } sshkey_format_cert_validity(host_key->cert, valid, sizeof(valid)); debug("Server host certificate: %s %s, serial %llu " "ID \"%s\" CA %s %s valid %s", sshkey_ssh_name(host_key), fp, (unsigned long long)host_key->cert->serial, host_key->cert->key_id, sshkey_ssh_name(host_key->cert->signature_key), cafp, valid); for (i = 0; i < host_key->cert->nprincipals; i++) { debug2("Server host certificate hostname: %s", host_key->cert->principals[i]); } } else { debug("Server host key: %s %s", sshkey_ssh_name(host_key), fp); } if (sshkey_equal(previous_host_key, host_key)) { debug2_f("server host key %s %s matches cached key", sshkey_type(host_key), fp); r = 0; goto out; } /* Check in RevokedHostKeys files if specified */ for (i = 0; i < options.num_revoked_host_keys; i++) { r = sshkey_check_revoked(host_key, options.revoked_host_keys[i]); switch (r) { case 0: break; /* not revoked */ case SSH_ERR_KEY_REVOKED: error("Host key %s %s revoked by file %s", sshkey_type(host_key), fp, options.revoked_host_keys[i]); r = -1; goto out; default: error_r(r, "Error checking host key %s %s in " "revoked keys file %s", sshkey_type(host_key), fp, options.revoked_host_keys[i]); r = -1; goto out; } } if (options.verify_host_key_dns) { /* * XXX certs are not yet supported for DNS, so downgrade * them and try the plain key. */ if ((r = sshkey_from_private(host_key, &plain)) != 0) goto out; if (sshkey_is_cert(plain)) sshkey_drop_cert(plain); if (verify_host_key_dns(host, hostaddr, plain, &flags) == 0) { if (flags & DNS_VERIFY_FOUND) { if (options.verify_host_key_dns == 1 && flags & DNS_VERIFY_MATCH && flags & DNS_VERIFY_SECURE) { r = 0; goto out; } if (flags & DNS_VERIFY_MATCH) { matching_host_key_dns = 1; } else { warn_changed_key(plain); error("Update the SSHFP RR in DNS " "with the new host key to get rid " "of this message."); } } } } r = check_host_key(host, cinfo, hostaddr, options.port, host_key, RDRW, 0, options.user_hostfiles, options.num_user_hostfiles, options.system_hostfiles, options.num_system_hostfiles, options.known_hosts_command); out: sshkey_free(plain); free(fp); free(cafp); if (r == 0 && host_key != NULL) { sshkey_free(previous_host_key); r = sshkey_from_private(host_key, &previous_host_key); } return r; } static void warn_nonpq_kex(void) { logit("** WARNING: connection is not using a post-quantum key exchange algorithm."); logit("** This session may be vulnerable to \"store now, decrypt later\" attacks."); logit("** The server may need to be upgraded. See https://openssh.com/pq.html"); } /* * 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(struct ssh *ssh, Sensitive *sensitive, const char *orighost, struct sockaddr *hostaddr, u_short port, struct passwd *pw, int timeout_ms, const struct ssh_conn_info *cinfo) { char *host; char *server_user, *local_user; int r; 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); lowercase(host); /* Exchange protocol version identification strings with the server. */ if ((r = kex_exchange_identification(ssh, timeout_ms, options.version_addendum)) != 0) sshpkt_fatal(ssh, r, "banner exchange"); if ((ssh->compat & SSH_BUG_NOREKEY)) { logit("Warning: this server does not support rekeying."); logit("This session will eventually fail"); } /* Put the connection into non-blocking mode. */ ssh_packet_set_nonblocking(ssh); /* key exchange */ /* authenticate user */ debug("Authenticating to %s:%d as '%s'", host, port, server_user); ssh_kex2(ssh, host, hostaddr, port, cinfo); if (!options.kex_algorithms_set && ssh->kex != NULL && ssh->kex->name != NULL && options.warn_weak_crypto && !kex_is_pq_from_name(ssh->kex->name)) warn_nonpq_kex(); ssh_userauth2(ssh, local_user, server_user, host, sensitive); free(local_user); free(host); } /* print all known host keys for a given host, but skip keys of given type */ static int show_other_keys(struct hostkeys *hostkeys, struct sshkey *key) { int type[] = { KEY_RSA, KEY_ECDSA, KEY_ED25519, -1 }; int i, ret = 0; char *fp, *ra; const struct hostkey_entry *found; for (i = 0; type[i] != -1; i++) { if (type[i] == key->type) continue; if (!lookup_key_in_hostkeys_by_type(hostkeys, type[i], -1, &found)) continue; fp = sshkey_fingerprint(found->key, options.fingerprint_hash, SSH_FP_DEFAULT); ra = sshkey_fingerprint(found->key, options.fingerprint_hash, SSH_FP_RANDOMART); if (fp == NULL || ra == NULL) fatal_f("sshkey_fingerprint fail"); logit("WARNING: %s key found for host %s\n" "in %s:%lu\n" "%s key fingerprint %s.", sshkey_type(found->key), found->host, found->file, found->line, sshkey_type(found->key), fp); if (options.visual_host_key) logit("%s", ra); free(ra); free(fp); ret = 1; } return ret; } static void warn_changed_key(struct sshkey *host_key) { char *fp; fp = sshkey_fingerprint(host_key, options.fingerprint_hash, SSH_FP_DEFAULT); if (fp == NULL) fatal_f("sshkey_fingerprint fail"); 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 a host key has just been changed."); error("The fingerprint for the %s key sent by the remote host is\n%s.", sshkey_type(host_key), fp); error("Please contact your system administrator."); free(fp); } /* * Execute a local command */ int ssh_local_cmd(const char *args) { char *shell; pid_t pid; int status; void (*osighand)(int); if (!options.permit_local_command || args == NULL || !*args) return (1); if ((shell = getenv("SHELL")) == NULL || *shell == '\0') shell = _PATH_BSHELL; osighand = ssh_signal(SIGCHLD, SIG_DFL); pid = fork(); if (pid == 0) { ssh_signal(SIGPIPE, SIG_DFL); 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)); ssh_signal(SIGCHLD, osighand); if (!WIFEXITED(status)) return (1); return (WEXITSTATUS(status)); } void maybe_add_key_to_agent(const char *authfile, struct sshkey *private, const char *comment, const char *passphrase) { int auth_sock = -1, r; const char *skprovider = NULL; if (options.add_keys_to_agent == 0) return; if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) { debug3("no authentication agent, not adding key"); return; } if (options.add_keys_to_agent == 2 && !ask_permission("Add key %s (%s) to agent?", authfile, comment)) { debug3("user denied adding this key"); close(auth_sock); return; } if (sshkey_is_sk(private)) skprovider = options.sk_provider; if ((r = ssh_add_identity_constrained(auth_sock, private, comment == NULL ? authfile : comment, options.add_keys_to_agent_lifespan, (options.add_keys_to_agent == 3), skprovider, NULL, 0)) == 0) debug("identity added to agent: %s", authfile); else debug("could not add identity to agent: %s (%d)", authfile, r); close(auth_sock); }