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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 14:40:04 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 14:40:04 +0000
commit25505898530a333011f4fd5cbc841ad6b26c089c (patch)
tree333a33fdd60930bcccc3f177ed9467d535e9bac6 /sshconnect.c
parentInitial commit. (diff)
downloadopenssh-25505898530a333011f4fd5cbc841ad6b26c089c.tar.xz
openssh-25505898530a333011f4fd5cbc841ad6b26c089c.zip
Adding upstream version 1:9.2p1.upstream/1%9.2p1upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to '')
-rw-r--r--sshconnect.c1722
1 files changed, 1722 insertions, 0 deletions
diff --git a/sshconnect.c b/sshconnect.c
new file mode 100644
index 0000000..792bc34
--- /dev/null
+++ b/sshconnect.c
@@ -0,0 +1,1722 @@
+/* $OpenBSD: sshconnect.c,v 1.361 2023/01/13 02:44:02 djm 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 <net/if.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+
+#include <ctype.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <netdb.h>
+#ifdef HAVE_PATHS_H
+#include <paths.h>
+#endif
+#include <pwd.h>
+#ifdef HAVE_POLL_H
+#include <poll.h>
+#endif
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdarg.h>
+#include <string.h>
+#include <unistd.h>
+#ifdef HAVE_IFADDRS_H
+# include <ifaddrs.h>
+#endif
+
+#include "xmalloc.h"
+#include "hostfile.h"
+#include "ssh.h"
+#include "sshbuf.h"
+#include "packet.h"
+#include "compat.h"
+#include "sshkey.h"
+#include "sshconnect.h"
+#include "log.h"
+#include "misc.h"
+#include "readconf.h"
+#include "atomicio.h"
+#include "dns.h"
+#include "monitor_fdpass.h"
+#include "ssh2.h"
+#include "version.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);
+}
+
+#ifdef HAVE_IFADDRS_H
+/*
+ * 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;
+}
+#endif
+
+/*
+ * 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;
+#ifdef HAVE_IFADDRS_H
+ struct ifaddrs *ifaddrs = NULL;
+#endif
+ 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;
+ }
+ 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) {
+#ifdef HAVE_IFADDRS_H
+ 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;
+ }
+#else
+ error("BindInterface not supported on this platform.");
+#endif
+ }
+ 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);
+#ifdef HAVE_IFADDRS_H
+ if (ifaddrs != NULL)
+ freeifaddrs(ifaddrs);
+#endif
+ 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;
+ }
+ 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];
+ socklen_t addrlen;
+
+ switch (hostaddr == NULL ? -1 : hostaddr->sa_family) {
+ case -1:
+ addrlen = 0;
+ break;
+ case AF_INET:
+ addrlen = sizeof(struct sockaddr_in);
+ break;
+ case AF_INET6:
+ addrlen = sizeof(struct sockaddr_in6);
+ break;
+ default:
+ addrlen = sizeof(struct sockaddr);
+ break;
+ }
+
+ /*
+ * 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, addrlen,
+ 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;
+}
+
+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 = {0, 0, 0, 0, 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:
+ /* 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, 0,
+ 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;
+ }
+
+ 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 file if specified */
+ if (options.revoked_host_keys != NULL) {
+ r = sshkey_check_revoked(host_key, options.revoked_host_keys);
+ 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);
+ 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);
+ 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;
+}
+
+/*
+ * 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, NULL)) != 0)
+ sshpkt_fatal(ssh, r, "banner exchange");
+
+ /* 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);
+ 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_DSA,
+ KEY_ECDSA,
+ KEY_ED25519,
+ KEY_XMSS,
+ -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), 0, 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);
+}