*/
#include "includes.h"
-RCSID("$OpenBSD: sshconnect.c,v 1.127 2002/06/27 08:49:44 markus Exp $");
+RCSID("$OpenBSD: sshconnect.c,v 1.163 2005/05/24 17:32:44 avsm Exp $");
#include <openssl/bn.h>
#include "readconf.h"
#include "atomicio.h"
#include "misc.h"
-#include "readpass.h"
+
+#include "dns.h"
char *client_version_string = NULL;
char *server_version_string = NULL;
+int matching_host_key_dns = 0;
+
/* import */
extern Options options;
extern char *__progname;
extern uid_t original_real_uid;
extern uid_t original_effective_uid;
+extern pid_t proxy_command_pid;
#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;
-}
+static int show_other_keys(const char *, Key *);
+static void warn_changed_key(Key *);
/*
* Connect to the given ssh server using a proxy command.
/* 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. */
+ /*
+ * Build the final command string in the buffer by making the
+ * appropriate substitutions to the given proxy command.
+ *
+ * Use "exec" to avoid "sh -c" processes on some platforms
+ * (e.g. Solaris)
+ */
buffer_init(&command);
+ buffer_append(&command, "exec ", 5);
+
for (cp = proxy_command; *cp; cp++) {
if (cp[0] == '%' && cp[1] == '%') {
buffer_append(&command, "%", 1);
/* Parent. */
if (pid < 0)
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]);
* Creates a (possibly privileged) socket for use as the ssh connection.
*/
static int
-ssh_create_socket(int privileged, int family)
+ssh_create_socket(int privileged, struct addrinfo *ai)
{
int sock, gaierr;
struct addrinfo hints, *res;
if (privileged) {
int p = IPPORT_RESERVED - 1;
PRIV_START;
- sock = rresvport_af(&p, family);
+ sock = rresvport_af(&p, ai->ai_family);
PRIV_END;
if (sock < 0)
- error("rresvport: af=%d %.100s", family, strerror(errno));
+ error("rresvport: af=%d %.100s", ai->ai_family,
+ strerror(errno));
else
debug("Allocated local port %d.", p);
return sock;
}
- sock = socket(family, SOCK_STREAM, 0);
+ sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
if (sock < 0)
error("socket: %.100s", strerror(errno));
return sock;
memset(&hints, 0, sizeof(hints));
- hints.ai_family = family;
- hints.ai_socktype = SOCK_STREAM;
+ hints.ai_family = ai->ai_family;
+ hints.ai_socktype = ai->ai_socktype;
+ hints.ai_protocol = ai->ai_protocol;
hints.ai_flags = AI_PASSIVE;
gaierr = getaddrinfo(options.bind_address, "0", &hints, &res);
if (gaierr) {
return sock;
}
+static int
+timeout_connect(int sockfd, const struct sockaddr *serv_addr,
+ socklen_t addrlen, int timeout)
+{
+ fd_set *fdset;
+ struct timeval tv;
+ socklen_t optlen;
+ int fdsetsz, optval, rc, result = -1;
+
+ if (timeout <= 0)
+ return (connect(sockfd, serv_addr, addrlen));
+
+ set_nonblock(sockfd);
+ rc = connect(sockfd, serv_addr, addrlen);
+ if (rc == 0) {
+ unset_nonblock(sockfd);
+ return (0);
+ }
+ if (errno != EINPROGRESS)
+ return (-1);
+
+ fdsetsz = howmany(sockfd + 1, NFDBITS) * sizeof(fd_mask);
+ fdset = (fd_set *)xmalloc(fdsetsz);
+
+ memset(fdset, 0, fdsetsz);
+ FD_SET(sockfd, fdset);
+ tv.tv_sec = timeout;
+ tv.tv_usec = 0;
+
+ for (;;) {
+ rc = select(sockfd + 1, NULL, fdset, NULL, &tv);
+ if (rc != -1 || errno != EINTR)
+ break;
+ }
+
+ switch (rc) {
+ case 0:
+ /* Timed out */
+ errno = ETIMEDOUT;
+ break;
+ case -1:
+ /* Select error */
+ debug("select: %s", strerror(errno));
+ break;
+ case 1:
+ /* Completed or failed */
+ optval = 0;
+ optlen = sizeof(optval);
+ if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &optval,
+ &optlen) == -1) {
+ debug("getsockopt: %s", strerror(errno));
+ break;
+ }
+ if (optval != 0) {
+ errno = optval;
+ break;
+ }
+ result = 0;
+ unset_nonblock(sockfd);
+ break;
+ default:
+ /* Should not occur */
+ fatal("Bogus return (%d) from select()", rc);
+ }
+
+ xfree(fdset);
+ return (result);
+}
+
/*
* Opens a TCP/IP connection to the remote server on the given host.
* The address of the remote host will be returned in hostaddr.
* 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,
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);
+ debug2("ssh_connect: needpriv %d", needpriv);
/* Get default port if port has not been set. */
if (port == 0) {
host, ntop, strport);
/* Create a socket for connecting. */
- sock = ssh_create_socket(needpriv, ai->ai_family);
+ sock = ssh_create_socket(needpriv, ai);
if (sock < 0)
/* Any error is already output */
continue;
- if (connect(sock, ai->ai_addr, ai->ai_addrlen) >= 0) {
+ if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
+ options.connection_timeout) >= 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));
+ debug("connect to address %s port %s: %s",
+ ntop, strport, strerror(errno));
/*
* Close the failed socket; there appear to
* be some problems when reusing a socket for
freeaddrinfo(aitop);
/* Return failure if we didn't get a successful connection. */
- if (attempt >= connection_attempts)
- return full_failure ? ECONNABORTED : ECONNREFUSED;
+ if (attempt >= connection_attempts) {
+ error("ssh: connect to host %s port %s: %s",
+ host, strport, strerror(errno));
+ return (-1);
+ }
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 &&
+ /* Set SO_KEEPALIVE if requested. */
+ if (options.tcp_keep_alive &&
setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
sizeof(on)) < 0)
error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
int connection_out = packet_get_connection_out();
int minor1 = PROTOCOL_MINOR_1;
- /* Read other side\'s version identification. */
+ /* 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)
+ size_t len = atomicio(read, connection_in, &buf[i], 1);
+
+ if (len != 1 && errno == EPIPE)
fatal("ssh_exchange_identification: Connection closed by remote host");
+ else if (len != 1)
+ fatal("ssh_exchange_identification: read: %.100s", strerror(errno));
if (buf[i] == '\r') {
buf[i] = '\n';
buf[i + 1] = 0;
enable_compat13();
minor1 = 3;
if (options.forward_agent) {
- log("Agent forwarding disabled for protocol 1.3");
+ logit("Agent forwarding disabled for protocol 1.3");
options.forward_agent = 0;
}
}
compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
compat20 ? PROTOCOL_MINOR_2 : minor1,
SSH_VERSION);
- if (atomicio(write, connection_out, buf, strlen(buf)) != strlen(buf))
+ if (atomicio(vwrite, connection_out, buf, strlen(buf)) != strlen(buf))
fatal("write: %.100s", strerror(errno));
client_version_string = xstrdup(buf);
chop(client_version_string);
int readonly, const char *user_hostfile, const char *system_hostfile)
{
Key *file_key;
- char *type = key_type(host_key);
+ const 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 r, local = 0, host_ip_differ = 0;
int salen;
char ntop[NI_MAXHOST];
char msg[1024];
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 "
+ logit("%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 "
+ host_key, options.hash_known_hosts))
+ logit("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 "
+ logit("Warning: Permanently added the %s host "
"key for IP address '%.128s' to the list "
"of known hosts.", type, ip);
}
"have requested strict checking.", type, host);
goto fail;
} else if (options.strict_host_key_checking == 2) {
+ char msg1[1024], msg2[1024];
+
+ if (show_other_keys(host, host_key))
+ snprintf(msg1, sizeof(msg1),
+ "\nbut keys of different type are already"
+ " known for this host.");
+ else
+ snprintf(msg1, sizeof(msg1), ".");
/* The default */
fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
+ msg2[0] = '\0';
+ if (options.verify_host_key_dns) {
+ if (matching_host_key_dns)
+ snprintf(msg2, sizeof(msg2),
+ "Matching host key fingerprint"
+ " found in DNS.\n");
+ else
+ snprintf(msg2, sizeof(msg2),
+ "No matching host key fingerprint"
+ " found in DNS.\n");
+ }
snprintf(msg, sizeof(msg),
"The authenticity of host '%.200s (%s)' can't be "
- "established.\n"
- "%s key fingerprint is %s.\n"
+ "established%s\n"
+ "%s key fingerprint is %s.\n%s"
"Are you sure you want to continue connecting "
- "(yes/no)? ", host, ip, type, fp);
+ "(yes/no)? ",
+ host, ip, msg1, type, fp, msg2);
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 "
+ 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_hostfile, host,
+ host_key, options.hash_known_hosts) &&
+ add_host_to_hostfile(user_hostfile, ip,
+ host_key, options.hash_known_hosts);
+ } else {
+ /* Add unhashed "host,ip" */
+ r = add_host_to_hostfile(user_hostfile,
+ hostline, host_key,
+ options.hash_known_hosts);
+ }
+ } else {
+ r = add_host_to_hostfile(user_hostfile, 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_hostfile);
else
- log("Warning: Permanently added '%.200s' (%s) to the "
+ logit("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;
+ char *key_msg;
if (ip_status == HOST_NEW)
- msg = "is unknown";
+ key_msg = "is unknown";
else if (ip_status == HOST_OK)
- msg = "is unchanged";
+ key_msg = "is unchanged";
else
- msg = "has a different value";
+ 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 according IP address %s", ip);
- error("%s. This could either mean that", msg);
+ 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:%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.");
+ warn_changed_key(host_key);
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
/*
* If strict host key checking has not been requested, allow
- * the connection but without password authentication or
+ * the connection but without MITM-able authentication or
* agent forwarding.
*/
if (options.password_authentication) {
"man-in-the-middle attacks.");
options.password_authentication = 0;
}
+ if (options.kbd_interactive_authentication) {
+ error("Keyboard-interactive authentication is disabled"
+ " to avoid man-in-the-middle attacks.");
+ options.kbd_interactive_authentication = 0;
+ options.challenge_response_authentication = 0;
+ }
+ if (options.challenge_response_authentication) {
+ error("Challenge/response authentication is disabled"
+ " to avoid man-in-the-middle attacks.");
+ options.challenge_response_authentication = 0;
+ }
if (options.forward_agent) {
error("Agent forwarding is disabled to avoid "
"man-in-the-middle attacks.");
* accept the authentication.
*/
break;
+ case HOST_FOUND:
+ fatal("internal error");
+ break;
}
if (options.check_host_ip && host_status != HOST_CHANGED &&
host_file, host_line);
}
if (options.strict_host_key_checking == 1) {
- log(msg);
+ logit("%s", msg);
error("Exiting, you have requested strict checking.");
goto fail;
} else if (options.strict_host_key_checking == 2) {
if (!confirm(msg))
goto fail;
} else {
- log(msg);
+ logit("%s", msg);
}
}
return -1;
}
+/* returns 0 if key verifies or -1 if key does NOT verify */
int
verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
{
struct stat st;
+ int flags = 0;
+
+ if (options.verify_host_key_dns &&
+ verify_host_key_dns(host, hostaddr, host_key, &flags) == 0) {
+
+ if (flags & DNS_VERIFY_FOUND) {
+
+ if (options.verify_host_key_dns == 1 &&
+ flags & DNS_VERIFY_MATCH &&
+ flags & DNS_VERIFY_SECURE)
+ return 0;
+
+ if (flags & DNS_VERIFY_MATCH) {
+ matching_host_key_dns = 1;
+ } else {
+ warn_changed_key(host_key);
+ error("Update the SSHFP RR in DNS with the new "
+ "host key to get rid of this message.");
+ }
+ }
+ }
/* return ok if the key can be found in an old keyfile */
if (stat(options.system_hostfile2, &st) == 0 ||
memset(padded, 0, size);
xfree(padded);
}
+
+static int
+show_key_from_file(const char *file, const char *host, int keytype)
+{
+ Key *found;
+ char *fp;
+ int line, ret;
+
+ found = key_new(keytype);
+ if ((ret = lookup_key_in_hostfile_by_type(file, host,
+ keytype, found, &line))) {
+ fp = key_fingerprint(found, SSH_FP_MD5, SSH_FP_HEX);
+ logit("WARNING: %s key found for host %s\n"
+ "in %s:%d\n"
+ "%s key fingerprint %s.",
+ key_type(found), host, file, line,
+ key_type(found), fp);
+ xfree(fp);
+ }
+ key_free(found);
+ return (ret);
+}
+
+/* print all known host keys for a given host, but skip keys of given type */
+static int
+show_other_keys(const char *host, Key *key)
+{
+ int type[] = { KEY_RSA1, KEY_RSA, KEY_DSA, -1};
+ int i, found = 0;
+
+ for (i = 0; type[i] != -1; i++) {
+ if (type[i] == key->type)
+ continue;
+ if (type[i] != KEY_RSA1 &&
+ show_key_from_file(options.user_hostfile2, host, type[i])) {
+ found = 1;
+ continue;
+ }
+ if (type[i] != KEY_RSA1 &&
+ show_key_from_file(options.system_hostfile2, host, type[i])) {
+ found = 1;
+ continue;
+ }
+ if (show_key_from_file(options.user_hostfile, host, type[i])) {
+ found = 1;
+ continue;
+ }
+ if (show_key_from_file(options.system_hostfile, host, type[i])) {
+ found = 1;
+ continue;
+ }
+ debug2("no key of type %d for host %s", type[i], host);
+ }
+ return (found);
+}
+
+static void
+warn_changed_key(Key *host_key)
+{
+ char *fp;
+ const char *type = key_type(host_key);
+
+ 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.");
+
+ xfree(fp);
+}
andersk / openssh.git / blobdiff