canohost.c - security/openssh-library - Rivoreo Source Code Repositories

 /*
  * 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 1.21 2001/02/08 19:30:51 itojun Exp $");

 #include "packet.h"
 #include "xmalloc.h"
 #include "log.h"
 #include "canohost.h"

 void	check_ip_options(int socket, char *ipaddr);

 /*
  * Return the canonical name of the host at the other end of the socket. The
  * caller should free the returned string with xfree.
  */

 char *
 get_remote_hostname(int socket, int reverse_mapping_check)
 {
 	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();
 	}
 #ifdef IPV4_IN_IPV6
 	if (from.ss_family == AF_INET6) {
 		struct sockaddr_in6 *from6 = (struct sockaddr_in6 *)&from;

 		/* Detect IPv4 in IPv6 mapped address and convert it to */
 		/* plain (AF_INET) IPv4 address */
 		if (IN6_IS_ADDR_V4MAPPED(&from6->sin6_addr)) {
 			struct sockaddr_in *from4 = (struct sockaddr_in *)&from;
 			struct in_addr addr;
 			u_int16_t port;

 			memcpy(&addr, ((char *)&from6->sin6_addr) + 12, sizeof(addr));
 			port = from6->sin6_port;

 			memset(&from, 0, sizeof(from));

 			from4->sin_family = AF_INET;
 			memcpy(&from4->sin_addr, &addr, sizeof(addr));
 			from4->sin_port = port;
 		}
 	}
 #endif
 	if (from.ss_family == AF_INET)
 		check_ip_options(socket, ntop);

 	if (getnameinfo((struct sockaddr *)&from, fromlen, ntop, sizeof(ntop),
 	     NULL, 0, NI_NUMERICHOST) != 0)
 		fatal("get_remote_hostname: getnameinfo NI_NUMERICHOST failed");

 	/* 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 (!reverse_mapping_check)
 		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 */
 void
 check_ip_options(int socket, char *ipaddr)
 {
 	u_char options[200], *ucp;
 	char text[1024], *cp;
 	socklen_t option_size;
 	int 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, (void *)options,
 	    &option_size) >= 0 && option_size != 0) {
 		cp = text;
 		/* Note: "text" buffer must be at least 3x as big as options. */
 		for (ucp = options; option_size > 0; ucp++, option_size--, cp += 3)
 			sprintf(cp, " %2.2x", *ucp);
 		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 reverse_mapping_check)
 {
 	static char *canonical_host_name = NULL;
 	static int reverse_mapping_checked = 0;

 	/* Check if we have previously retrieved name with same option. */
 	if (canonical_host_name != NULL) {
 		if (reverse_mapping_checked != reverse_mapping_check)
 			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(), reverse_mapping_check);
 	else
 		canonical_host_name = xstrdup("UNKNOWN");

 	reverse_mapping_checked = reverse_mapping_check;
 	return canonical_host_name;
 }

 /*
  * Returns the remote IP-address of socket as a string.  The returned
  * string must be freed.
  */

 char *
 get_peer_ipaddr(int socket)
 {
 	struct sockaddr_storage from;
 	socklen_t fromlen;
 	char ntop[NI_MAXHOST];

 	/* Get IP address of client. */
 	fromlen = sizeof(from);
 	memset(&from, 0, sizeof(from));
 	if (getpeername(socket, (struct sockaddr *) & from, &fromlen) < 0) {
 		debug("get_peer_ipaddr: getpeername failed: %.100s", strerror(errno));
 		return NULL;
 	}
 	/* Get the IP address in ascii. */
 	if (getnameinfo((struct sockaddr *)&from, fromlen, ntop, sizeof(ntop),
 	     NULL, 0, NI_NUMERICHOST) != 0) {
 		error("get_peer_ipaddr: getnameinfo NI_NUMERICHOST failed");
 		return NULL;
 	}
 	return xstrdup(ntop);
 }

 /*
  * Returns the IP-address of the remote host as a string.  The returned
  * string must not be freed.
  */

 const char *
 get_remote_ipaddr()
 {
 	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;
 }

 /* Returns the local/remote port for the socket. */

 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. */

 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()
 {
 	return get_port(0);
 }

 int
 get_local_port()
 {
 	return get_port(1);
 }
	/*
	* 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 1.21 2001/02/08 19:30:51 itojun Exp $");

	#include "packet.h"
	#include "xmalloc.h"
	#include "log.h"
	#include "canohost.h"

	void check_ip_options(int socket, char *ipaddr);

	/*
	* Return the canonical name of the host at the other end of the socket. The
	* caller should free the returned string with xfree.
	*/

	char *
	get_remote_hostname(int socket, int reverse_mapping_check)
	{
	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();
	}
	#ifdef IPV4_IN_IPV6
	if (from.ss_family == AF_INET6) {
	struct sockaddr_in6 from6 = (struct sockaddr_in6 )&from;

	/* Detect IPv4 in IPv6 mapped address and convert it to */
	/* plain (AF_INET) IPv4 address */
	if (IN6_IS_ADDR_V4MAPPED(&from6->sin6_addr)) {
	struct sockaddr_in from4 = (struct sockaddr_in )&from;
	struct in_addr addr;
	u_int16_t port;

	memcpy(&addr, ((char *)&from6->sin6_addr) + 12, sizeof(addr));
	port = from6->sin6_port;

	memset(&from, 0, sizeof(from));

	from4->sin_family = AF_INET;
	memcpy(&from4->sin_addr, &addr, sizeof(addr));
	from4->sin_port = port;
	}
	}
	#endif
	if (from.ss_family == AF_INET)
	check_ip_options(socket, ntop);

	if (getnameinfo((struct sockaddr *)&from, fromlen, ntop, sizeof(ntop),
	NULL, 0, NI_NUMERICHOST) != 0)
	fatal("get_remote_hostname: getnameinfo NI_NUMERICHOST failed");

	/* 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 (!reverse_mapping_check)
	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 */
	void
	check_ip_options(int socket, char *ipaddr)
	{
	u_char options[200], *ucp;
	char text[1024], *cp;
	socklen_t option_size;
	int 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, (void *)options,
	&option_size) >= 0 && option_size != 0) {
	cp = text;
	/* Note: "text" buffer must be at least 3x as big as options. */
	for (ucp = options; option_size > 0; ucp++, option_size--, cp += 3)
	sprintf(cp, " %2.2x", *ucp);
	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 reverse_mapping_check)
	{
	static char *canonical_host_name = NULL;
	static int reverse_mapping_checked = 0;

	/* Check if we have previously retrieved name with same option. */
	if (canonical_host_name != NULL) {
	if (reverse_mapping_checked != reverse_mapping_check)
	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(), reverse_mapping_check);
	else
	canonical_host_name = xstrdup("UNKNOWN");

	reverse_mapping_checked = reverse_mapping_check;
	return canonical_host_name;
	}

	/*
	* Returns the remote IP-address of socket as a string. The returned
	* string must be freed.
	*/

	char *
	get_peer_ipaddr(int socket)
	{
	struct sockaddr_storage from;
	socklen_t fromlen;
	char ntop[NI_MAXHOST];

	/* Get IP address of client. */
	fromlen = sizeof(from);
	memset(&from, 0, sizeof(from));
	if (getpeername(socket, (struct sockaddr *) & from, &fromlen) < 0) {
	debug("get_peer_ipaddr: getpeername failed: %.100s", strerror(errno));
	return NULL;
	}
	/* Get the IP address in ascii. */
	if (getnameinfo((struct sockaddr *)&from, fromlen, ntop, sizeof(ntop),
	NULL, 0, NI_NUMERICHOST) != 0) {
	error("get_peer_ipaddr: getnameinfo NI_NUMERICHOST failed");
	return NULL;
	}
	return xstrdup(ntop);
	}

	/*
	* Returns the IP-address of the remote host as a string. The returned
	* string must not be freed.
	*/

	const char *
	get_remote_ipaddr()
	{
	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;
	}

	/* Returns the local/remote port for the socket. */

	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. */

	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()
	{
	return get_port(0);
	}

	int
	get_local_port()
	{
	return get_port(1);
	}