After we moved to git $FreeBSD$ is no longer expanded and serves no purpose. Remove them from OpenSSH to reduce diffs against upstream. Sponsored by: The FreeBSD Foundation
1710 lines
48 KiB
C
1710 lines
48 KiB
C
/* $OpenBSD: sshconnect.c,v 1.356 2021/12/19 22:10:24 djm Exp $ */
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/*
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* Author: Tatu Ylonen <ylo@cs.hut.fi>
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* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
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* All rights reserved
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* Code to connect to a remote host, and to perform the client side of the
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* login (authentication) dialog.
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*
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* As far as I am concerned, the code I have written for this software
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* can be used freely for any purpose. Any derived versions of this
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* software must be clearly marked as such, and if the derived work is
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* incompatible with the protocol description in the RFC file, it must be
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* called by a name other than "ssh" or "Secure Shell".
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*/
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#include "includes.h"
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#include <sys/types.h>
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#include <sys/wait.h>
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#include <sys/stat.h>
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#include <sys/socket.h>
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#ifdef HAVE_SYS_TIME_H
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# include <sys/time.h>
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#endif
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#include <net/if.h>
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#include <netinet/in.h>
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#include <arpa/inet.h>
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#include <ctype.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <limits.h>
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#include <netdb.h>
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#ifdef HAVE_PATHS_H
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#include <paths.h>
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#endif
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#include <pwd.h>
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#ifdef HAVE_POLL_H
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#include <poll.h>
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#endif
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#include <signal.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <stdarg.h>
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#include <string.h>
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#include <unistd.h>
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#ifdef HAVE_IFADDRS_H
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# include <ifaddrs.h>
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#endif
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#include "xmalloc.h"
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#include "hostfile.h"
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#include "ssh.h"
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#include "sshbuf.h"
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#include "packet.h"
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#include "compat.h"
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#include "sshkey.h"
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#include "sshconnect.h"
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#include "log.h"
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#include "misc.h"
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#include "readconf.h"
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#include "atomicio.h"
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#include "dns.h"
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#include "monitor_fdpass.h"
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#include "ssh2.h"
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#include "version.h"
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#include "authfile.h"
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#include "ssherr.h"
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#include "authfd.h"
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#include "kex.h"
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struct sshkey *previous_host_key = NULL;
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static int matching_host_key_dns = 0;
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static pid_t proxy_command_pid = 0;
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/* import */
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extern int debug_flag;
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extern Options options;
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extern char *__progname;
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static int show_other_keys(struct hostkeys *, struct sshkey *);
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static void warn_changed_key(struct sshkey *);
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/* Expand a proxy command */
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static char *
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expand_proxy_command(const char *proxy_command, const char *user,
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const char *host, const char *host_arg, int port)
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{
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char *tmp, *ret, strport[NI_MAXSERV];
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const char *keyalias = options.host_key_alias ?
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options.host_key_alias : host_arg;
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snprintf(strport, sizeof strport, "%d", port);
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xasprintf(&tmp, "exec %s", proxy_command);
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ret = percent_expand(tmp,
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"h", host,
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"k", keyalias,
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"n", host_arg,
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"p", strport,
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"r", options.user,
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(char *)NULL);
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free(tmp);
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return ret;
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}
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/*
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* Connect to the given ssh server using a proxy command that passes a
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* a connected fd back to us.
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*/
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static int
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ssh_proxy_fdpass_connect(struct ssh *ssh, const char *host,
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const char *host_arg, u_short port, const char *proxy_command)
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{
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char *command_string;
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int sp[2], sock;
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pid_t pid;
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char *shell;
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if ((shell = getenv("SHELL")) == NULL)
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shell = _PATH_BSHELL;
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if (socketpair(AF_UNIX, SOCK_STREAM, 0, sp) == -1)
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fatal("Could not create socketpair to communicate with "
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"proxy dialer: %.100s", strerror(errno));
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command_string = expand_proxy_command(proxy_command, options.user,
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host, host_arg, port);
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debug("Executing proxy dialer command: %.500s", command_string);
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/* Fork and execute the proxy command. */
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if ((pid = fork()) == 0) {
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char *argv[10];
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close(sp[1]);
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/* Redirect stdin and stdout. */
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if (sp[0] != 0) {
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if (dup2(sp[0], 0) == -1)
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perror("dup2 stdin");
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}
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if (sp[0] != 1) {
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if (dup2(sp[0], 1) == -1)
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perror("dup2 stdout");
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}
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if (sp[0] >= 2)
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close(sp[0]);
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/*
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* Stderr is left for non-ControlPersist connections is so
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* error messages may be printed on the user's terminal.
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*/
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if (!debug_flag && options.control_path != NULL &&
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options.control_persist && stdfd_devnull(0, 0, 1) == -1)
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error_f("stdfd_devnull failed");
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argv[0] = shell;
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argv[1] = "-c";
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argv[2] = command_string;
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argv[3] = NULL;
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/*
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* Execute the proxy command.
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* Note that we gave up any extra privileges above.
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*/
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execv(argv[0], argv);
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perror(argv[0]);
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exit(1);
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}
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/* Parent. */
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if (pid == -1)
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fatal("fork failed: %.100s", strerror(errno));
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close(sp[0]);
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free(command_string);
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if ((sock = mm_receive_fd(sp[1])) == -1)
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fatal("proxy dialer did not pass back a connection");
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close(sp[1]);
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while (waitpid(pid, NULL, 0) == -1)
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if (errno != EINTR)
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fatal("Couldn't wait for child: %s", strerror(errno));
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/* Set the connection file descriptors. */
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if (ssh_packet_set_connection(ssh, sock, sock) == NULL)
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return -1; /* ssh_packet_set_connection logs error */
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return 0;
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}
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/*
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* Connect to the given ssh server using a proxy command.
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*/
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static int
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ssh_proxy_connect(struct ssh *ssh, const char *host, const char *host_arg,
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u_short port, const char *proxy_command)
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{
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char *command_string;
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int pin[2], pout[2];
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pid_t pid;
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char *shell;
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if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
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shell = _PATH_BSHELL;
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/* Create pipes for communicating with the proxy. */
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if (pipe(pin) == -1 || pipe(pout) == -1)
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fatal("Could not create pipes to communicate with the proxy: %.100s",
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strerror(errno));
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command_string = expand_proxy_command(proxy_command, options.user,
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host, host_arg, port);
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debug("Executing proxy command: %.500s", command_string);
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/* Fork and execute the proxy command. */
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if ((pid = fork()) == 0) {
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char *argv[10];
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/* Redirect stdin and stdout. */
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close(pin[1]);
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if (pin[0] != 0) {
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if (dup2(pin[0], 0) == -1)
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perror("dup2 stdin");
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close(pin[0]);
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}
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close(pout[0]);
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if (dup2(pout[1], 1) == -1)
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perror("dup2 stdout");
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/* Cannot be 1 because pin allocated two descriptors. */
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close(pout[1]);
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/*
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* Stderr is left for non-ControlPersist connections is so
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* error messages may be printed on the user's terminal.
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*/
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if (!debug_flag && options.control_path != NULL &&
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options.control_persist && stdfd_devnull(0, 0, 1) == -1)
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error_f("stdfd_devnull failed");
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argv[0] = shell;
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argv[1] = "-c";
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argv[2] = command_string;
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argv[3] = NULL;
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/*
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* Execute the proxy command. Note that we gave up any
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* extra privileges above.
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*/
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ssh_signal(SIGPIPE, SIG_DFL);
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execv(argv[0], argv);
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perror(argv[0]);
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exit(1);
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}
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/* Parent. */
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if (pid == -1)
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fatal("fork failed: %.100s", strerror(errno));
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else
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proxy_command_pid = pid; /* save pid to clean up later */
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/* Close child side of the descriptors. */
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close(pin[0]);
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close(pout[1]);
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/* Free the command name. */
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free(command_string);
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/* Set the connection file descriptors. */
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if (ssh_packet_set_connection(ssh, pout[0], pin[1]) == NULL)
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return -1; /* ssh_packet_set_connection logs error */
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return 0;
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}
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void
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ssh_kill_proxy_command(void)
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{
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/*
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* Send SIGHUP to proxy command if used. We don't wait() in
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* case it hangs and instead rely on init to reap the child
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*/
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if (proxy_command_pid > 1)
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kill(proxy_command_pid, SIGHUP);
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}
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#ifdef HAVE_IFADDRS_H
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/*
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* Search a interface address list (returned from getifaddrs(3)) for an
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* address that matches the desired address family on the specified interface.
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* Returns 0 and fills in *resultp and *rlenp on success. Returns -1 on failure.
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*/
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static int
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check_ifaddrs(const char *ifname, int af, const struct ifaddrs *ifaddrs,
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struct sockaddr_storage *resultp, socklen_t *rlenp)
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{
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struct sockaddr_in6 *sa6;
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struct sockaddr_in *sa;
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struct in6_addr *v6addr;
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const struct ifaddrs *ifa;
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int allow_local;
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/*
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* Prefer addresses that are not loopback or linklocal, but use them
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* if nothing else matches.
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*/
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for (allow_local = 0; allow_local < 2; allow_local++) {
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for (ifa = ifaddrs; ifa != NULL; ifa = ifa->ifa_next) {
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if (ifa->ifa_addr == NULL || ifa->ifa_name == NULL ||
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(ifa->ifa_flags & IFF_UP) == 0 ||
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ifa->ifa_addr->sa_family != af ||
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strcmp(ifa->ifa_name, options.bind_interface) != 0)
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continue;
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switch (ifa->ifa_addr->sa_family) {
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case AF_INET:
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sa = (struct sockaddr_in *)ifa->ifa_addr;
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if (!allow_local && sa->sin_addr.s_addr ==
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htonl(INADDR_LOOPBACK))
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continue;
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if (*rlenp < sizeof(struct sockaddr_in)) {
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error_f("v4 addr doesn't fit");
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return -1;
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}
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*rlenp = sizeof(struct sockaddr_in);
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memcpy(resultp, sa, *rlenp);
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return 0;
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case AF_INET6:
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sa6 = (struct sockaddr_in6 *)ifa->ifa_addr;
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v6addr = &sa6->sin6_addr;
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if (!allow_local &&
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(IN6_IS_ADDR_LINKLOCAL(v6addr) ||
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IN6_IS_ADDR_LOOPBACK(v6addr)))
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continue;
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if (*rlenp < sizeof(struct sockaddr_in6)) {
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error_f("v6 addr doesn't fit");
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return -1;
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}
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*rlenp = sizeof(struct sockaddr_in6);
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memcpy(resultp, sa6, *rlenp);
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return 0;
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}
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}
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}
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return -1;
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}
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#endif
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/*
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* Creates a socket for use as the ssh connection.
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*/
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static int
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ssh_create_socket(struct addrinfo *ai)
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{
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int sock, r;
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struct sockaddr_storage bindaddr;
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socklen_t bindaddrlen = 0;
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struct addrinfo hints, *res = NULL;
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#ifdef HAVE_IFADDRS_H
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struct ifaddrs *ifaddrs = NULL;
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#endif
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char ntop[NI_MAXHOST];
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sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
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if (sock == -1) {
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error("socket: %s", strerror(errno));
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return -1;
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}
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fcntl(sock, F_SETFD, FD_CLOEXEC);
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/* Use interactive QOS (if specified) until authentication completed */
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if (options.ip_qos_interactive != INT_MAX)
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set_sock_tos(sock, options.ip_qos_interactive);
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/* Bind the socket to an alternative local IP address */
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if (options.bind_address == NULL && options.bind_interface == NULL)
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return sock;
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if (options.bind_address != NULL) {
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memset(&hints, 0, sizeof(hints));
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hints.ai_family = ai->ai_family;
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hints.ai_socktype = ai->ai_socktype;
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hints.ai_protocol = ai->ai_protocol;
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hints.ai_flags = AI_PASSIVE;
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if ((r = getaddrinfo(options.bind_address, NULL,
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&hints, &res)) != 0) {
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error("getaddrinfo: %s: %s", options.bind_address,
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ssh_gai_strerror(r));
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goto fail;
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}
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if (res == NULL) {
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error("getaddrinfo: no addrs");
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goto fail;
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}
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memcpy(&bindaddr, res->ai_addr, res->ai_addrlen);
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bindaddrlen = res->ai_addrlen;
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} else if (options.bind_interface != NULL) {
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#ifdef HAVE_IFADDRS_H
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if ((r = getifaddrs(&ifaddrs)) != 0) {
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error("getifaddrs: %s: %s", options.bind_interface,
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strerror(errno));
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goto fail;
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}
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bindaddrlen = sizeof(bindaddr);
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if (check_ifaddrs(options.bind_interface, ai->ai_family,
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ifaddrs, &bindaddr, &bindaddrlen) != 0) {
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logit("getifaddrs: %s: no suitable addresses",
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options.bind_interface);
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goto fail;
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}
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#else
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error("BindInterface not supported on this platform.");
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#endif
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}
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if ((r = getnameinfo((struct sockaddr *)&bindaddr, bindaddrlen,
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ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST)) != 0) {
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error_f("getnameinfo failed: %s", ssh_gai_strerror(r));
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goto fail;
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}
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if (bind(sock, (struct sockaddr *)&bindaddr, bindaddrlen) != 0) {
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error("bind %s: %s", ntop, strerror(errno));
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goto fail;
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}
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debug_f("bound to %s", ntop);
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/* success */
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goto out;
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fail:
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close(sock);
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sock = -1;
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out:
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if (res != NULL)
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freeaddrinfo(res);
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#ifdef HAVE_IFADDRS_H
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if (ifaddrs != NULL)
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freeifaddrs(ifaddrs);
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#endif
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return sock;
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}
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|
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/*
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* Opens a TCP/IP connection to the remote server on the given host.
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* The address of the remote host will be returned in hostaddr.
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* If port is 0, the default port will be used.
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* Connection_attempts specifies the maximum number of tries (one per
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* second). If proxy_command is non-NULL, it specifies the command (with %h
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* and %p substituted for host and port, respectively) to use to contact
|
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* the daemon.
|
|
*/
|
|
static int
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ssh_connect_direct(struct ssh *ssh, const char *host, struct addrinfo *aitop,
|
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struct sockaddr_storage *hostaddr, u_short port, int connection_attempts,
|
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int *timeout_ms, int want_keepalive)
|
|
{
|
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int on = 1, saved_timeout_ms = *timeout_ms;
|
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int oerrno, sock = -1, attempt;
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char ntop[NI_MAXHOST], strport[NI_MAXSERV];
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struct addrinfo *ai;
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|
|
|
debug3_f("entering");
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memset(ntop, 0, sizeof(ntop));
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|
memset(strport, 0, sizeof(strport));
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|
|
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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;
|
|
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;
|
|
}
|
|
|
|
/*
|
|
* 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);
|
|
error("Add correct host key in %.100s to get rid of this message.",
|
|
user_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,
|
|
options.version_addendum)) != 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);
|
|
}
|