336 lines
9.0 KiB
C
336 lines
9.0 KiB
C
/*
|
|
* Author: Tatu Ylonen <ylo@cs.hut.fi>
|
|
* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
|
|
* All rights reserved
|
|
* Functions for returning the canonical host name of the remote site.
|
|
*
|
|
* 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: canohost.c,v 1.32 2002/06/11 08:11:45 itojun Exp $");
|
|
|
|
#include "packet.h"
|
|
#include "xmalloc.h"
|
|
#include "log.h"
|
|
#include "canohost.h"
|
|
|
|
static void check_ip_options(int, char *);
|
|
|
|
/*
|
|
* Return the canonical name of the host at the other end of the socket. The
|
|
* caller should free the returned string with xfree.
|
|
*/
|
|
|
|
static char *
|
|
get_remote_hostname(int socket, int verify_reverse_mapping)
|
|
{
|
|
struct sockaddr_storage from;
|
|
int i;
|
|
socklen_t fromlen;
|
|
struct addrinfo hints, *ai, *aitop;
|
|
char name[NI_MAXHOST], ntop[NI_MAXHOST], ntop2[NI_MAXHOST];
|
|
|
|
/* Get IP address of client. */
|
|
fromlen = sizeof(from);
|
|
memset(&from, 0, sizeof(from));
|
|
if (getpeername(socket, (struct sockaddr *) &from, &fromlen) < 0) {
|
|
debug("getpeername failed: %.100s", strerror(errno));
|
|
fatal_cleanup();
|
|
}
|
|
|
|
if (getnameinfo((struct sockaddr *)&from, fromlen, ntop, sizeof(ntop),
|
|
NULL, 0, NI_NUMERICHOST) != 0)
|
|
fatal("get_remote_hostname: getnameinfo NI_NUMERICHOST failed");
|
|
|
|
if (from.ss_family == AF_INET)
|
|
check_ip_options(socket, ntop);
|
|
|
|
debug3("Trying to reverse map address %.100s.", ntop);
|
|
/* Map the IP address to a host name. */
|
|
if (getnameinfo((struct sockaddr *)&from, fromlen, name, sizeof(name),
|
|
NULL, 0, NI_NAMEREQD) != 0) {
|
|
/* Host name not found. Use ip address. */
|
|
log("Could not reverse map address %.100s.", ntop);
|
|
return xstrdup(ntop);
|
|
}
|
|
|
|
/* Got host name. */
|
|
name[sizeof(name) - 1] = '\0';
|
|
/*
|
|
* Convert it to all lowercase (which is expected by the rest
|
|
* of this software).
|
|
*/
|
|
for (i = 0; name[i]; i++)
|
|
if (isupper(name[i]))
|
|
name[i] = tolower(name[i]);
|
|
|
|
if (!verify_reverse_mapping)
|
|
return xstrdup(name);
|
|
/*
|
|
* Map it back to an IP address and check that the given
|
|
* address actually is an address of this host. This is
|
|
* necessary because anyone with access to a name server can
|
|
* define arbitrary names for an IP address. Mapping from
|
|
* name to IP address can be trusted better (but can still be
|
|
* fooled if the intruder has access to the name server of
|
|
* the domain).
|
|
*/
|
|
memset(&hints, 0, sizeof(hints));
|
|
hints.ai_family = from.ss_family;
|
|
hints.ai_socktype = SOCK_STREAM;
|
|
if (getaddrinfo(name, NULL, &hints, &aitop) != 0) {
|
|
log("reverse mapping checking getaddrinfo for %.700s "
|
|
"failed - POSSIBLE BREAKIN ATTEMPT!", name);
|
|
return xstrdup(ntop);
|
|
}
|
|
/* Look for the address from the list of addresses. */
|
|
for (ai = aitop; ai; ai = ai->ai_next) {
|
|
if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop2,
|
|
sizeof(ntop2), NULL, 0, NI_NUMERICHOST) == 0 &&
|
|
(strcmp(ntop, ntop2) == 0))
|
|
break;
|
|
}
|
|
freeaddrinfo(aitop);
|
|
/* If we reached the end of the list, the address was not there. */
|
|
if (!ai) {
|
|
/* Address not found for the host name. */
|
|
log("Address %.100s maps to %.600s, but this does not "
|
|
"map back to the address - POSSIBLE BREAKIN ATTEMPT!",
|
|
ntop, name);
|
|
return xstrdup(ntop);
|
|
}
|
|
return xstrdup(name);
|
|
}
|
|
|
|
/*
|
|
* If IP options are supported, make sure there are none (log and
|
|
* disconnect them if any are found). Basically we are worried about
|
|
* source routing; it can be used to pretend you are somebody
|
|
* (ip-address) you are not. That itself may be "almost acceptable"
|
|
* under certain circumstances, but rhosts autentication is useless
|
|
* if source routing is accepted. Notice also that if we just dropped
|
|
* source routing here, the other side could use IP spoofing to do
|
|
* rest of the interaction and could still bypass security. So we
|
|
* exit here if we detect any IP options.
|
|
*/
|
|
/* IPv4 only */
|
|
static void
|
|
check_ip_options(int socket, char *ipaddr)
|
|
{
|
|
u_char options[200];
|
|
char text[sizeof(options) * 3 + 1];
|
|
socklen_t option_size;
|
|
int i, ipproto;
|
|
struct protoent *ip;
|
|
|
|
if ((ip = getprotobyname("ip")) != NULL)
|
|
ipproto = ip->p_proto;
|
|
else
|
|
ipproto = IPPROTO_IP;
|
|
option_size = sizeof(options);
|
|
if (getsockopt(socket, ipproto, IP_OPTIONS, options,
|
|
&option_size) >= 0 && option_size != 0) {
|
|
text[0] = '\0';
|
|
for (i = 0; i < option_size; i++)
|
|
snprintf(text + i*3, sizeof(text) - i*3,
|
|
" %2.2x", options[i]);
|
|
log("Connection from %.100s with IP options:%.800s",
|
|
ipaddr, text);
|
|
packet_disconnect("Connection from %.100s with IP options:%.800s",
|
|
ipaddr, text);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Return the canonical name of the host in the other side of the current
|
|
* connection. The host name is cached, so it is efficient to call this
|
|
* several times.
|
|
*/
|
|
|
|
const char *
|
|
get_canonical_hostname(int verify_reverse_mapping)
|
|
{
|
|
static char *canonical_host_name = NULL;
|
|
static int verify_reverse_mapping_done = 0;
|
|
|
|
/* Check if we have previously retrieved name with same option. */
|
|
if (canonical_host_name != NULL) {
|
|
if (verify_reverse_mapping_done != verify_reverse_mapping)
|
|
xfree(canonical_host_name);
|
|
else
|
|
return canonical_host_name;
|
|
}
|
|
|
|
/* Get the real hostname if socket; otherwise return UNKNOWN. */
|
|
if (packet_connection_is_on_socket())
|
|
canonical_host_name = get_remote_hostname(
|
|
packet_get_connection_in(), verify_reverse_mapping);
|
|
else
|
|
canonical_host_name = xstrdup("UNKNOWN");
|
|
|
|
verify_reverse_mapping_done = verify_reverse_mapping;
|
|
return canonical_host_name;
|
|
}
|
|
|
|
/*
|
|
* Returns the remote IP-address of socket as a string. The returned
|
|
* string must be freed.
|
|
*/
|
|
static char *
|
|
get_socket_address(int socket, int remote, int flags)
|
|
{
|
|
struct sockaddr_storage addr;
|
|
socklen_t addrlen;
|
|
char ntop[NI_MAXHOST];
|
|
|
|
/* Get IP address of client. */
|
|
addrlen = sizeof(addr);
|
|
memset(&addr, 0, sizeof(addr));
|
|
|
|
if (remote) {
|
|
if (getpeername(socket, (struct sockaddr *)&addr, &addrlen)
|
|
< 0) {
|
|
debug("get_socket_ipaddr: getpeername failed: %.100s",
|
|
strerror(errno));
|
|
return NULL;
|
|
}
|
|
} else {
|
|
if (getsockname(socket, (struct sockaddr *)&addr, &addrlen)
|
|
< 0) {
|
|
debug("get_socket_ipaddr: getsockname failed: %.100s",
|
|
strerror(errno));
|
|
return NULL;
|
|
}
|
|
}
|
|
/* Get the address in ascii. */
|
|
if (getnameinfo((struct sockaddr *)&addr, addrlen, ntop, sizeof(ntop),
|
|
NULL, 0, flags) != 0) {
|
|
error("get_socket_ipaddr: getnameinfo %d failed", flags);
|
|
return NULL;
|
|
}
|
|
return xstrdup(ntop);
|
|
}
|
|
|
|
char *
|
|
get_peer_ipaddr(int socket)
|
|
{
|
|
return get_socket_address(socket, 1, NI_NUMERICHOST);
|
|
}
|
|
|
|
char *
|
|
get_local_ipaddr(int socket)
|
|
{
|
|
return get_socket_address(socket, 0, NI_NUMERICHOST);
|
|
}
|
|
|
|
char *
|
|
get_local_name(int socket)
|
|
{
|
|
return get_socket_address(socket, 0, NI_NAMEREQD);
|
|
}
|
|
|
|
/*
|
|
* Returns the IP-address of the remote host as a string. The returned
|
|
* string must not be freed.
|
|
*/
|
|
|
|
const char *
|
|
get_remote_ipaddr(void)
|
|
{
|
|
static char *canonical_host_ip = NULL;
|
|
|
|
/* Check whether we have cached the ipaddr. */
|
|
if (canonical_host_ip == NULL) {
|
|
if (packet_connection_is_on_socket()) {
|
|
canonical_host_ip =
|
|
get_peer_ipaddr(packet_get_connection_in());
|
|
if (canonical_host_ip == NULL)
|
|
fatal_cleanup();
|
|
} else {
|
|
/* If not on socket, return UNKNOWN. */
|
|
canonical_host_ip = xstrdup("UNKNOWN");
|
|
}
|
|
}
|
|
return canonical_host_ip;
|
|
}
|
|
|
|
const char *
|
|
get_remote_name_or_ip(u_int utmp_len, int verify_reverse_mapping)
|
|
{
|
|
static const char *remote = "";
|
|
if (utmp_len > 0)
|
|
remote = get_canonical_hostname(verify_reverse_mapping);
|
|
if (utmp_len == 0 || strlen(remote) > utmp_len)
|
|
remote = get_remote_ipaddr();
|
|
return remote;
|
|
}
|
|
|
|
/* Returns the local/remote port for the socket. */
|
|
|
|
static int
|
|
get_sock_port(int sock, int local)
|
|
{
|
|
struct sockaddr_storage from;
|
|
socklen_t fromlen;
|
|
char strport[NI_MAXSERV];
|
|
|
|
/* Get IP address of client. */
|
|
fromlen = sizeof(from);
|
|
memset(&from, 0, sizeof(from));
|
|
if (local) {
|
|
if (getsockname(sock, (struct sockaddr *)&from, &fromlen) < 0) {
|
|
error("getsockname failed: %.100s", strerror(errno));
|
|
return 0;
|
|
}
|
|
} else {
|
|
if (getpeername(sock, (struct sockaddr *) & from, &fromlen) < 0) {
|
|
debug("getpeername failed: %.100s", strerror(errno));
|
|
fatal_cleanup();
|
|
}
|
|
}
|
|
/* Return port number. */
|
|
if (getnameinfo((struct sockaddr *)&from, fromlen, NULL, 0,
|
|
strport, sizeof(strport), NI_NUMERICSERV) != 0)
|
|
fatal("get_sock_port: getnameinfo NI_NUMERICSERV failed");
|
|
return atoi(strport);
|
|
}
|
|
|
|
/* Returns remote/local port number for the current connection. */
|
|
|
|
static int
|
|
get_port(int local)
|
|
{
|
|
/*
|
|
* If the connection is not a socket, return 65535. This is
|
|
* intentionally chosen to be an unprivileged port number.
|
|
*/
|
|
if (!packet_connection_is_on_socket())
|
|
return 65535;
|
|
|
|
/* Get socket and return the port number. */
|
|
return get_sock_port(packet_get_connection_in(), local);
|
|
}
|
|
|
|
int
|
|
get_peer_port(int sock)
|
|
{
|
|
return get_sock_port(sock, 0);
|
|
}
|
|
|
|
int
|
|
get_remote_port(void)
|
|
{
|
|
return get_port(0);
|
|
}
|
|
|
|
int
|
|
get_local_port(void)
|
|
{
|
|
return get_port(1);
|
|
}
|