72a8e501f7
Sponsored by: DARPA, NAI Labs
872 lines
25 KiB
C
872 lines
25 KiB
C
/*
|
|
* Author: Tatu Ylonen <ylo@cs.hut.fi>
|
|
* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
|
|
* All rights reserved
|
|
* Code to connect to a remote host, and to perform the client side of the
|
|
* login (authentication) dialog.
|
|
*
|
|
* As far as I am concerned, the code I have written for this software
|
|
* can be used freely for any purpose. Any derived versions of this
|
|
* software must be clearly marked as such, and if the derived work is
|
|
* incompatible with the protocol description in the RFC file, it must be
|
|
* called by a name other than "ssh" or "Secure Shell".
|
|
*/
|
|
|
|
#include "includes.h"
|
|
RCSID("$OpenBSD: sshconnect.c,v 1.126 2002/06/23 03:30:17 deraadt Exp $");
|
|
RCSID("$FreeBSD$");
|
|
|
|
#include <openssl/bn.h>
|
|
|
|
#include "ssh.h"
|
|
#include "xmalloc.h"
|
|
#include "rsa.h"
|
|
#include "buffer.h"
|
|
#include "packet.h"
|
|
#include "uidswap.h"
|
|
#include "compat.h"
|
|
#include "key.h"
|
|
#include "sshconnect.h"
|
|
#include "hostfile.h"
|
|
#include "log.h"
|
|
#include "readconf.h"
|
|
#include "atomicio.h"
|
|
#include "misc.h"
|
|
#include "readpass.h"
|
|
|
|
char *client_version_string = NULL;
|
|
char *server_version_string = NULL;
|
|
|
|
/* import */
|
|
extern Options options;
|
|
extern char *__progname;
|
|
extern uid_t original_real_uid;
|
|
extern uid_t original_effective_uid;
|
|
|
|
#ifndef INET6_ADDRSTRLEN /* for non IPv6 machines */
|
|
#define INET6_ADDRSTRLEN 46
|
|
#endif
|
|
|
|
static const char *
|
|
sockaddr_ntop(struct sockaddr *sa, socklen_t salen)
|
|
{
|
|
static char addrbuf[NI_MAXHOST];
|
|
|
|
if (getnameinfo(sa, salen, addrbuf, sizeof(addrbuf), NULL, 0,
|
|
NI_NUMERICHOST) != 0)
|
|
fatal("sockaddr_ntop: getnameinfo NI_NUMERICHOST failed");
|
|
return addrbuf;
|
|
}
|
|
|
|
/*
|
|
* Connect to the given ssh server using a proxy command.
|
|
*/
|
|
static int
|
|
ssh_proxy_connect(const char *host, u_short port, const char *proxy_command)
|
|
{
|
|
Buffer command;
|
|
const char *cp;
|
|
char *command_string;
|
|
int pin[2], pout[2];
|
|
pid_t pid;
|
|
char strport[NI_MAXSERV];
|
|
|
|
/* Convert the port number into a string. */
|
|
snprintf(strport, sizeof strport, "%hu", port);
|
|
|
|
/* Build the final command string in the buffer by making the
|
|
appropriate substitutions to the given proxy command. */
|
|
buffer_init(&command);
|
|
for (cp = proxy_command; *cp; cp++) {
|
|
if (cp[0] == '%' && cp[1] == '%') {
|
|
buffer_append(&command, "%", 1);
|
|
cp++;
|
|
continue;
|
|
}
|
|
if (cp[0] == '%' && cp[1] == 'h') {
|
|
buffer_append(&command, host, strlen(host));
|
|
cp++;
|
|
continue;
|
|
}
|
|
if (cp[0] == '%' && cp[1] == 'p') {
|
|
buffer_append(&command, strport, strlen(strport));
|
|
cp++;
|
|
continue;
|
|
}
|
|
buffer_append(&command, cp, 1);
|
|
}
|
|
buffer_append(&command, "\0", 1);
|
|
|
|
/* Get the final command string. */
|
|
command_string = buffer_ptr(&command);
|
|
|
|
/* Create pipes for communicating with the proxy. */
|
|
if (pipe(pin) < 0 || pipe(pout) < 0)
|
|
fatal("Could not create pipes to communicate with the proxy: %.100s",
|
|
strerror(errno));
|
|
|
|
debug("Executing proxy command: %.500s", command_string);
|
|
|
|
/* Fork and execute the proxy command. */
|
|
if ((pid = fork()) == 0) {
|
|
char *argv[10];
|
|
|
|
/* Child. Permanently give up superuser privileges. */
|
|
seteuid(original_real_uid);
|
|
setuid(original_real_uid);
|
|
|
|
/* Redirect stdin and stdout. */
|
|
close(pin[1]);
|
|
if (pin[0] != 0) {
|
|
if (dup2(pin[0], 0) < 0)
|
|
perror("dup2 stdin");
|
|
close(pin[0]);
|
|
}
|
|
close(pout[0]);
|
|
if (dup2(pout[1], 1) < 0)
|
|
perror("dup2 stdout");
|
|
/* Cannot be 1 because pin allocated two descriptors. */
|
|
close(pout[1]);
|
|
|
|
/* Stderr is left as it is so that error messages get
|
|
printed on the user's terminal. */
|
|
argv[0] = _PATH_BSHELL;
|
|
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 < 0)
|
|
fatal("fork failed: %.100s", strerror(errno));
|
|
|
|
/* Close child side of the descriptors. */
|
|
close(pin[0]);
|
|
close(pout[1]);
|
|
|
|
/* Free the command name. */
|
|
buffer_free(&command);
|
|
|
|
/* Set the connection file descriptors. */
|
|
packet_set_connection(pout[0], pin[1]);
|
|
|
|
/* Indicate OK return */
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Creates a (possibly privileged) socket for use as the ssh connection.
|
|
*/
|
|
static int
|
|
ssh_create_socket(int privileged, int family)
|
|
{
|
|
int sock, gaierr;
|
|
struct addrinfo hints, *res;
|
|
|
|
/*
|
|
* If we are running as root and want to connect to a privileged
|
|
* port, bind our own socket to a privileged port.
|
|
*/
|
|
if (privileged) {
|
|
int p = IPPORT_RESERVED - 1;
|
|
PRIV_START;
|
|
sock = rresvport_af(&p, family);
|
|
PRIV_END;
|
|
if (sock < 0)
|
|
error("rresvport: af=%d %.100s", family, strerror(errno));
|
|
else
|
|
debug("Allocated local port %d.", p);
|
|
return sock;
|
|
}
|
|
sock = socket(family, SOCK_STREAM, 0);
|
|
if (sock < 0)
|
|
error("socket: %.100s", strerror(errno));
|
|
|
|
/* Bind the socket to an alternative local IP address */
|
|
if (options.bind_address == NULL)
|
|
return sock;
|
|
|
|
memset(&hints, 0, sizeof(hints));
|
|
hints.ai_family = family;
|
|
hints.ai_socktype = SOCK_STREAM;
|
|
hints.ai_flags = AI_PASSIVE;
|
|
gaierr = getaddrinfo(options.bind_address, "0", &hints, &res);
|
|
if (gaierr) {
|
|
error("getaddrinfo: %s: %s", options.bind_address,
|
|
gai_strerror(gaierr));
|
|
close(sock);
|
|
return -1;
|
|
}
|
|
if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) {
|
|
error("bind: %s: %s", options.bind_address, strerror(errno));
|
|
close(sock);
|
|
freeaddrinfo(res);
|
|
return -1;
|
|
}
|
|
freeaddrinfo(res);
|
|
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. If needpriv is true,
|
|
* a privileged port will be allocated to make the connection.
|
|
* This requires super-user privileges if needpriv is true.
|
|
* 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.
|
|
* Return values:
|
|
* 0 for OK
|
|
* ECONNREFUSED if we got a "Connection Refused" by the peer on any address
|
|
* ECONNABORTED if we failed without a "Connection refused"
|
|
* Suitable error messages for the connection failure will already have been
|
|
* printed.
|
|
*/
|
|
int
|
|
ssh_connect(const char *host, struct sockaddr_storage * hostaddr,
|
|
u_short port, int family, int connection_attempts,
|
|
int needpriv, const char *proxy_command)
|
|
{
|
|
int gaierr;
|
|
int on = 1;
|
|
int sock = -1, attempt;
|
|
char ntop[NI_MAXHOST], strport[NI_MAXSERV];
|
|
struct addrinfo hints, *ai, *aitop;
|
|
struct linger linger;
|
|
struct servent *sp;
|
|
/*
|
|
* Did we get only other errors than "Connection refused" (which
|
|
* should block fallback to rsh and similar), or did we get at least
|
|
* one "Connection refused"?
|
|
*/
|
|
int full_failure = 1;
|
|
|
|
debug("ssh_connect: needpriv %d", needpriv);
|
|
|
|
/* Get default port if port has not been set. */
|
|
if (port == 0) {
|
|
sp = getservbyname(SSH_SERVICE_NAME, "tcp");
|
|
if (sp)
|
|
port = ntohs(sp->s_port);
|
|
else
|
|
port = SSH_DEFAULT_PORT;
|
|
}
|
|
/* If a proxy command is given, connect using it. */
|
|
if (proxy_command != NULL)
|
|
return ssh_proxy_connect(host, port, proxy_command);
|
|
|
|
/* No proxy command. */
|
|
|
|
memset(&hints, 0, sizeof(hints));
|
|
hints.ai_family = family;
|
|
hints.ai_socktype = SOCK_STREAM;
|
|
snprintf(strport, sizeof strport, "%u", port);
|
|
if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0)
|
|
fatal("%s: %.100s: %s", __progname, host,
|
|
gai_strerror(gaierr));
|
|
|
|
/*
|
|
* Try to connect several times. On some machines, the first time
|
|
* will sometimes fail. In general socket code appears to behave
|
|
* quite magically on many machines.
|
|
*/
|
|
for (attempt = 0; ;) {
|
|
if (attempt > 0)
|
|
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)
|
|
continue;
|
|
if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
|
|
ntop, sizeof(ntop), strport, sizeof(strport),
|
|
NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
|
|
error("ssh_connect: getnameinfo failed");
|
|
continue;
|
|
}
|
|
debug("Connecting to %.200s [%.100s] port %s.",
|
|
host, ntop, strport);
|
|
|
|
/* Create a socket for connecting. */
|
|
sock = ssh_create_socket(needpriv, ai->ai_family);
|
|
if (sock < 0)
|
|
/* Any error is already output */
|
|
continue;
|
|
|
|
if (connect(sock, ai->ai_addr, ai->ai_addrlen) >= 0) {
|
|
/* Successful connection. */
|
|
memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
|
|
break;
|
|
} else {
|
|
if (errno == ECONNREFUSED)
|
|
full_failure = 0;
|
|
log("ssh: connect to address %s port %s: %s",
|
|
sockaddr_ntop(ai->ai_addr, ai->ai_addrlen),
|
|
strport, strerror(errno));
|
|
/*
|
|
* Close the failed socket; there appear to
|
|
* be some problems when reusing a socket for
|
|
* which connect() has already returned an
|
|
* error.
|
|
*/
|
|
close(sock);
|
|
}
|
|
}
|
|
if (ai)
|
|
break; /* Successful connection. */
|
|
|
|
attempt++;
|
|
if (attempt >= connection_attempts)
|
|
break;
|
|
/* Sleep a moment before retrying. */
|
|
sleep(1);
|
|
}
|
|
|
|
freeaddrinfo(aitop);
|
|
|
|
/* Return failure if we didn't get a successful connection. */
|
|
if (attempt >= connection_attempts)
|
|
return full_failure ? ECONNABORTED : ECONNREFUSED;
|
|
|
|
debug("Connection established.");
|
|
|
|
/*
|
|
* Set socket options. We would like the socket to disappear as soon
|
|
* as it has been closed for whatever reason.
|
|
*/
|
|
/* setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */
|
|
linger.l_onoff = 1;
|
|
linger.l_linger = 5;
|
|
setsockopt(sock, SOL_SOCKET, SO_LINGER, (void *)&linger, sizeof(linger));
|
|
|
|
/* Set keepalives if requested. */
|
|
if (options.keepalives &&
|
|
setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
|
|
sizeof(on)) < 0)
|
|
error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
|
|
|
|
/* Set the connection. */
|
|
packet_set_connection(sock, sock);
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Waits for the server identification string, and sends our own
|
|
* identification string.
|
|
*/
|
|
static void
|
|
ssh_exchange_identification(void)
|
|
{
|
|
char buf[256], remote_version[256]; /* must be same size! */
|
|
int remote_major, remote_minor, i, mismatch;
|
|
int connection_in = packet_get_connection_in();
|
|
int connection_out = packet_get_connection_out();
|
|
int minor1 = PROTOCOL_MINOR_1;
|
|
|
|
/* Read other side\'s version identification. */
|
|
for (;;) {
|
|
for (i = 0; i < sizeof(buf) - 1; i++) {
|
|
int len = atomicio(read, connection_in, &buf[i], 1);
|
|
if (len < 0)
|
|
fatal("ssh_exchange_identification: read: %.100s", strerror(errno));
|
|
if (len != 1)
|
|
fatal("ssh_exchange_identification: Connection closed by remote host");
|
|
if (buf[i] == '\r') {
|
|
buf[i] = '\n';
|
|
buf[i + 1] = 0;
|
|
continue; /**XXX wait for \n */
|
|
}
|
|
if (buf[i] == '\n') {
|
|
buf[i + 1] = 0;
|
|
break;
|
|
}
|
|
}
|
|
buf[sizeof(buf) - 1] = 0;
|
|
if (strncmp(buf, "SSH-", 4) == 0)
|
|
break;
|
|
debug("ssh_exchange_identification: %s", buf);
|
|
}
|
|
server_version_string = xstrdup(buf);
|
|
|
|
/*
|
|
* Check that the versions match. In future this might accept
|
|
* several versions and set appropriate flags to handle them.
|
|
*/
|
|
if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
|
|
&remote_major, &remote_minor, remote_version) != 3)
|
|
fatal("Bad remote protocol version identification: '%.100s'", buf);
|
|
debug("Remote protocol version %d.%d, remote software version %.100s",
|
|
remote_major, remote_minor, remote_version);
|
|
|
|
compat_datafellows(remote_version);
|
|
mismatch = 0;
|
|
|
|
switch (remote_major) {
|
|
case 1:
|
|
if (remote_minor == 99 &&
|
|
(options.protocol & SSH_PROTO_2) &&
|
|
!(options.protocol & SSH_PROTO_1_PREFERRED)) {
|
|
enable_compat20();
|
|
break;
|
|
}
|
|
if (!(options.protocol & SSH_PROTO_1)) {
|
|
mismatch = 1;
|
|
break;
|
|
}
|
|
if (remote_minor < 3) {
|
|
fatal("Remote machine has too old SSH software version.");
|
|
} else if (remote_minor == 3 || remote_minor == 4) {
|
|
/* We speak 1.3, too. */
|
|
enable_compat13();
|
|
minor1 = 3;
|
|
if (options.forward_agent) {
|
|
log("Agent forwarding disabled for protocol 1.3");
|
|
options.forward_agent = 0;
|
|
}
|
|
}
|
|
break;
|
|
case 2:
|
|
if (options.protocol & SSH_PROTO_2) {
|
|
enable_compat20();
|
|
break;
|
|
}
|
|
/* FALLTHROUGH */
|
|
default:
|
|
mismatch = 1;
|
|
break;
|
|
}
|
|
if (mismatch)
|
|
fatal("Protocol major versions differ: %d vs. %d",
|
|
(options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
|
|
remote_major);
|
|
/* Send our own protocol version identification. */
|
|
snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n",
|
|
compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
|
|
compat20 ? PROTOCOL_MINOR_2 : minor1,
|
|
SSH_VERSION);
|
|
if (atomicio(write, connection_out, buf, strlen(buf)) != strlen(buf))
|
|
fatal("write: %.100s", strerror(errno));
|
|
client_version_string = xstrdup(buf);
|
|
chop(client_version_string);
|
|
chop(server_version_string);
|
|
debug("Local version string %.100s", client_version_string);
|
|
}
|
|
|
|
/* defaults to 'no' */
|
|
static int
|
|
confirm(const char *prompt)
|
|
{
|
|
const char *msg, *again = "Please type 'yes' or 'no': ";
|
|
char *p;
|
|
int ret = -1;
|
|
|
|
if (options.batch_mode)
|
|
return 0;
|
|
for (msg = prompt;;msg = again) {
|
|
p = read_passphrase(msg, RP_ECHO);
|
|
if (p == NULL ||
|
|
(p[0] == '\0') || (p[0] == '\n') ||
|
|
strncasecmp(p, "no", 2) == 0)
|
|
ret = 0;
|
|
if (strncasecmp(p, "yes", 3) == 0)
|
|
ret = 1;
|
|
if (p)
|
|
xfree(p);
|
|
if (ret != -1)
|
|
return ret;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* check whether the supplied host key is valid, return -1 if the key
|
|
* is not valid. the user_hostfile will not be updated if 'readonly' is true.
|
|
*/
|
|
static int
|
|
check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key,
|
|
int readonly, const char *user_hostfile, const char *system_hostfile)
|
|
{
|
|
Key *file_key;
|
|
char *type = key_type(host_key);
|
|
char *ip = NULL;
|
|
char hostline[1000], *hostp, *fp;
|
|
HostStatus host_status;
|
|
HostStatus ip_status;
|
|
int local = 0, host_ip_differ = 0;
|
|
int salen;
|
|
char ntop[NI_MAXHOST];
|
|
char msg[1024];
|
|
int len, host_line, ip_line;
|
|
const char *host_file = NULL, *ip_file = NULL;
|
|
|
|
/*
|
|
* 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.
|
|
*/
|
|
/** hostaddr == 0! */
|
|
switch (hostaddr->sa_family) {
|
|
case AF_INET:
|
|
local = (ntohl(((struct sockaddr_in *)hostaddr)->
|
|
sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
|
|
salen = sizeof(struct sockaddr_in);
|
|
break;
|
|
case AF_INET6:
|
|
local = IN6_IS_ADDR_LOOPBACK(
|
|
&(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
|
|
salen = sizeof(struct sockaddr_in6);
|
|
break;
|
|
default:
|
|
local = 0;
|
|
salen = sizeof(struct sockaddr_storage);
|
|
break;
|
|
}
|
|
if (options.no_host_authentication_for_localhost == 1 && local &&
|
|
options.host_key_alias == NULL) {
|
|
debug("Forcing accepting of host key for "
|
|
"loopback/localhost.");
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* We don't have the remote ip-address for connections
|
|
* using a proxy command
|
|
*/
|
|
if (options.proxy_command == NULL) {
|
|
if (getnameinfo(hostaddr, salen, ntop, sizeof(ntop),
|
|
NULL, 0, NI_NUMERICHOST) != 0)
|
|
fatal("check_host_key: getnameinfo failed");
|
|
ip = xstrdup(ntop);
|
|
} else {
|
|
ip = xstrdup("<no hostip for proxy command>");
|
|
}
|
|
/*
|
|
* 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(host, ip) == 0 || options.proxy_command != NULL))
|
|
options.check_host_ip = 0;
|
|
|
|
/*
|
|
* Allow the user to record the key under a different name. This is
|
|
* useful for ssh tunneling over forwarded connections or if you run
|
|
* multiple sshd's on different ports on the same machine.
|
|
*/
|
|
if (options.host_key_alias != NULL) {
|
|
host = options.host_key_alias;
|
|
debug("using hostkeyalias: %s", host);
|
|
}
|
|
|
|
/*
|
|
* Store the host key from the known host file in here so that we can
|
|
* compare it with the key for the IP address.
|
|
*/
|
|
file_key = key_new(host_key->type);
|
|
|
|
/*
|
|
* Check if the host key is present in the user\'s list of known
|
|
* hosts or in the systemwide list.
|
|
*/
|
|
host_file = user_hostfile;
|
|
host_status = check_host_in_hostfile(host_file, host, host_key,
|
|
file_key, &host_line);
|
|
if (host_status == HOST_NEW) {
|
|
host_file = system_hostfile;
|
|
host_status = check_host_in_hostfile(host_file, host, host_key,
|
|
file_key, &host_line);
|
|
}
|
|
/*
|
|
* Also perform check for the ip address, skip the check if we are
|
|
* localhost or the hostname was an ip address to begin with
|
|
*/
|
|
if (options.check_host_ip) {
|
|
Key *ip_key = key_new(host_key->type);
|
|
|
|
ip_file = user_hostfile;
|
|
ip_status = check_host_in_hostfile(ip_file, ip, host_key,
|
|
ip_key, &ip_line);
|
|
if (ip_status == HOST_NEW) {
|
|
ip_file = system_hostfile;
|
|
ip_status = check_host_in_hostfile(ip_file, ip,
|
|
host_key, ip_key, &ip_line);
|
|
}
|
|
if (host_status == HOST_CHANGED &&
|
|
(ip_status != HOST_CHANGED || !key_equal(ip_key, file_key)))
|
|
host_ip_differ = 1;
|
|
|
|
key_free(ip_key);
|
|
} else
|
|
ip_status = host_status;
|
|
|
|
key_free(file_key);
|
|
|
|
switch (host_status) {
|
|
case HOST_OK:
|
|
/* The host is known and the key matches. */
|
|
debug("Host '%.200s' is known and matches the %s host key.",
|
|
host, type);
|
|
debug("Found key in %s:%d", host_file, host_line);
|
|
if (options.check_host_ip && ip_status == HOST_NEW) {
|
|
if (readonly)
|
|
log("%s host key for IP address "
|
|
"'%.128s' not in list of known hosts.",
|
|
type, ip);
|
|
else if (!add_host_to_hostfile(user_hostfile, ip,
|
|
host_key))
|
|
log("Failed to add the %s host key for IP "
|
|
"address '%.128s' to the list of known "
|
|
"hosts (%.30s).", type, ip, user_hostfile);
|
|
else
|
|
log("Warning: Permanently added the %s host "
|
|
"key for IP address '%.128s' to the list "
|
|
"of known hosts.", type, ip);
|
|
}
|
|
break;
|
|
case HOST_NEW:
|
|
if (readonly)
|
|
goto fail;
|
|
/* The host is new. */
|
|
if (options.strict_host_key_checking == 1) {
|
|
/*
|
|
* 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 == 2) {
|
|
/* The default */
|
|
fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
|
|
snprintf(msg, sizeof(msg),
|
|
"The authenticity of host '%.200s (%s)' can't be "
|
|
"established.\n"
|
|
"%s key fingerprint is %s.\n"
|
|
"Are you sure you want to continue connecting "
|
|
"(yes/no)? ", host, ip, type, fp);
|
|
xfree(fp);
|
|
if (!confirm(msg))
|
|
goto fail;
|
|
}
|
|
if (options.check_host_ip && ip_status == HOST_NEW) {
|
|
snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
|
|
hostp = hostline;
|
|
} else
|
|
hostp = host;
|
|
|
|
/*
|
|
* If not in strict mode, add the key automatically to the
|
|
* local known_hosts file.
|
|
*/
|
|
if (!add_host_to_hostfile(user_hostfile, hostp, host_key))
|
|
log("Failed to add the host to the list of known "
|
|
"hosts (%.500s).", user_hostfile);
|
|
else
|
|
log("Warning: Permanently added '%.200s' (%s) to the "
|
|
"list of known hosts.", hostp, type);
|
|
break;
|
|
case HOST_CHANGED:
|
|
if (options.check_host_ip && host_ip_differ) {
|
|
char *msg;
|
|
if (ip_status == HOST_NEW)
|
|
msg = "is unknown";
|
|
else if (ip_status == HOST_OK)
|
|
msg = "is unchanged";
|
|
else
|
|
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 according IP address %s", ip);
|
|
error("%s. This could either mean that", 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:%d", ip_file, ip_line);
|
|
}
|
|
/* The host key has changed. */
|
|
fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
|
|
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 the %s host key has just been changed.", type);
|
|
error("The fingerprint for the %s key sent by the remote host is\n%s.",
|
|
type, fp);
|
|
error("Please contact your system administrator.");
|
|
error("Add correct host key in %.100s to get rid of this message.",
|
|
user_hostfile);
|
|
error("Offending key in %s:%d", host_file, host_line);
|
|
xfree(fp);
|
|
|
|
/*
|
|
* 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) {
|
|
error("%s host key for %.200s has changed and you have "
|
|
"requested strict checking.", type, host);
|
|
goto fail;
|
|
}
|
|
|
|
/*
|
|
* If strict host key checking has not been requested, allow
|
|
* the connection but without password authentication or
|
|
* agent forwarding.
|
|
*/
|
|
if (options.password_authentication) {
|
|
error("Password authentication is disabled to avoid "
|
|
"man-in-the-middle attacks.");
|
|
options.password_authentication = 0;
|
|
}
|
|
if (options.forward_agent) {
|
|
error("Agent forwarding is disabled to avoid "
|
|
"man-in-the-middle attacks.");
|
|
options.forward_agent = 0;
|
|
}
|
|
if (options.forward_x11) {
|
|
error("X11 forwarding is disabled to avoid "
|
|
"man-in-the-middle attacks.");
|
|
options.forward_x11 = 0;
|
|
}
|
|
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;
|
|
}
|
|
/*
|
|
* 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 he/she whishes to
|
|
* accept the authentication.
|
|
*/
|
|
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:%d",
|
|
type, host, ip, ip_file, ip_line);
|
|
if (host_status == HOST_OK) {
|
|
len = strlen(msg);
|
|
snprintf(msg + len, sizeof(msg) - len,
|
|
"\nMatching host key in %s:%d",
|
|
host_file, host_line);
|
|
}
|
|
if (options.strict_host_key_checking == 1) {
|
|
log(msg);
|
|
error("Exiting, you have requested strict checking.");
|
|
goto fail;
|
|
} else if (options.strict_host_key_checking == 2) {
|
|
strlcat(msg, "\nAre you sure you want "
|
|
"to continue connecting (yes/no)? ", sizeof(msg));
|
|
if (!confirm(msg))
|
|
goto fail;
|
|
} else {
|
|
log(msg);
|
|
}
|
|
}
|
|
|
|
xfree(ip);
|
|
return 0;
|
|
|
|
fail:
|
|
xfree(ip);
|
|
return -1;
|
|
}
|
|
|
|
int
|
|
verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
|
|
{
|
|
struct stat st;
|
|
|
|
/* return ok if the key can be found in an old keyfile */
|
|
if (stat(options.system_hostfile2, &st) == 0 ||
|
|
stat(options.user_hostfile2, &st) == 0) {
|
|
if (check_host_key(host, hostaddr, host_key, /*readonly*/ 1,
|
|
options.user_hostfile2, options.system_hostfile2) == 0)
|
|
return 0;
|
|
}
|
|
return check_host_key(host, hostaddr, host_key, /*readonly*/ 0,
|
|
options.user_hostfile, options.system_hostfile);
|
|
}
|
|
|
|
/*
|
|
* 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(Sensitive *sensitive, const char *orighost,
|
|
struct sockaddr *hostaddr, struct passwd *pw)
|
|
{
|
|
char *host, *cp;
|
|
char *server_user, *local_user;
|
|
|
|
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);
|
|
for (cp = host; *cp; cp++)
|
|
if (isupper(*cp))
|
|
*cp = tolower(*cp);
|
|
|
|
/* Exchange protocol version identification strings with the server. */
|
|
ssh_exchange_identification();
|
|
|
|
/* Put the connection into non-blocking mode. */
|
|
packet_set_nonblocking();
|
|
|
|
/* key exchange */
|
|
/* authenticate user */
|
|
if (compat20) {
|
|
ssh_kex2(host, hostaddr);
|
|
ssh_userauth2(local_user, server_user, host, sensitive);
|
|
} else {
|
|
ssh_kex(host, hostaddr);
|
|
ssh_userauth1(local_user, server_user, host, sensitive);
|
|
}
|
|
}
|
|
|
|
void
|
|
ssh_put_password(char *password)
|
|
{
|
|
int size;
|
|
char *padded;
|
|
|
|
if (datafellows & SSH_BUG_PASSWORDPAD) {
|
|
packet_put_cstring(password);
|
|
return;
|
|
}
|
|
size = roundup(strlen(password) + 1, 32);
|
|
padded = xmalloc(size);
|
|
memset(padded, 0, size);
|
|
strlcpy(padded, password, size);
|
|
packet_put_string(padded, size);
|
|
memset(padded, 0, size);
|
|
xfree(padded);
|
|
}
|