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sshconnect.c
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/* $OpenBSD: sshconnect.c,v 1.363 2023/03/10 07:17:08 dtucker Exp $ */
/*
* Author: Tatu Ylonen <[email protected]>
* Copyright (c) 1995 Tatu Ylonen <[email protected]>, 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 "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;
}
(void)fcntl(sock, F_SETFD, FD_CLOEXEC);
/* Use interactive QOS (if specified) until authentication completed */
if (options.ip_qos_interactive != INT_MAX)
set_sock_tos(sock, options.ip_qos_interactive);
/* Bind the socket to an alternative local IP address */
if (options.bind_address == NULL && options.bind_interface == NULL)
return sock;
if (options.bind_address != NULL) {
memset(&hints, 0, sizeof(hints));
hints.ai_family = ai->ai_family;
hints.ai_socktype = ai->ai_socktype;
hints.ai_protocol = ai->ai_protocol;
hints.ai_flags = AI_PASSIVE;
if ((r = getaddrinfo(options.bind_address, NULL,
&hints, &res)) != 0) {
error("getaddrinfo: %s: %s", options.bind_address,
ssh_gai_strerror(r));
goto fail;
}
if (res == NULL) {
error("getaddrinfo: no addrs");
goto fail;
}
memcpy(&bindaddr, res->ai_addr, res->ai_addrlen);
bindaddrlen = res->ai_addrlen;
} else if (options.bind_interface != NULL) {
#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();