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/* $OpenBSD: canohost.c,v 1.73 2016/03/07 19:02:43 djm Exp $ */
/*
* 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"
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <errno.h>
#include <netdb.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdarg.h>
#include <unistd.h>
#include "xmalloc.h"
#include "packet.h"
#include "log.h"
#include "canohost.h"
#include "misc.h"
/*
* Returns the remote DNS hostname as a string. The returned string must not
* be freed. NB. this will usually trigger a DNS query the first time it is
* called.
* This function does additional checks on the hostname to mitigate some
* attacks on legacy rhosts-style authentication.
* XXX is RhostsRSAAuthentication vulnerable to these?
* XXX Can we remove these checks? (or if not, remove RhostsRSAAuthentication?)
*/
char *
remote_hostname(struct ssh *ssh)
{
struct sockaddr_storage from;
socklen_t fromlen;
struct addrinfo hints, *ai, *aitop;
char name[NI_MAXHOST], ntop2[NI_MAXHOST];
const char *ntop = ssh_remote_ipaddr(ssh);
/* Get IP address of client. */
fromlen = sizeof(from);
memset(&from, 0, sizeof(from));
if (getpeername(ssh_packet_get_connection_in(ssh),
(struct sockaddr *)&from, &fromlen) < 0) {
debug("getpeername failed: %.100s", strerror(errno));
return strdup(ntop);
}
ipv64_normalise_mapped(&from, &fromlen);
if (from.ss_family == AF_INET6)
fromlen = sizeof(struct sockaddr_in6);
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. */
return strdup(ntop);
}
/*
* if reverse lookup result looks like a numeric hostname,
* someone is trying to trick us by PTR record like following:
* 1.1.1.10.in-addr.arpa. IN PTR 2.3.4.5
*/
memset(&hints, 0, sizeof(hints));
hints.ai_socktype = SOCK_DGRAM; /*dummy*/
hints.ai_flags = AI_NUMERICHOST;
if (getaddrinfo(name, NULL, &hints, &ai) == 0) {
logit("Nasty PTR record \"%s\" is set up for %s, ignoring",
name, ntop);
freeaddrinfo(ai);
return strdup(ntop);
}
/* Names are stored in lowercase. */
lowercase(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) {
logit("reverse mapping checking getaddrinfo for %.700s "
"[%s] failed.", name, ntop);
return strdup(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 == NULL) {
/* Address not found for the host name. */
logit("Address %.100s maps to %.600s, but this does not "
"map back to the address.", ntop, name);
return strdup(ntop);
}
return strdup(name);
}
void
ipv64_normalise_mapped(struct sockaddr_storage *addr, socklen_t *len)
{
struct sockaddr_in6 *a6 = (struct sockaddr_in6 *)addr;
struct sockaddr_in *a4 = (struct sockaddr_in *)addr;
struct in_addr inaddr;
u_int16_t port;
if (addr->ss_family != AF_INET6 ||
!IN6_IS_ADDR_V4MAPPED(&a6->sin6_addr))
return;
debug3("Normalising mapped IPv4 in IPv6 address");
memcpy(&inaddr, ((char *)&a6->sin6_addr) + 12, sizeof(inaddr));
port = a6->sin6_port;
memset(a4, 0, sizeof(*a4));
a4->sin_family = AF_INET;
*len = sizeof(*a4);
memcpy(&a4->sin_addr, &inaddr, sizeof(inaddr));
a4->sin_port = port;
}
/*
* Returns the local/remote IP-address/hostname of socket as a string.
* The returned string must be freed.
*/
static char *
get_socket_address(int sock, int remote, int flags)
{
struct sockaddr_storage addr;
socklen_t addrlen;
char ntop[NI_MAXHOST];
int r;
/* Get IP address of client. */
addrlen = sizeof(addr);
memset(&addr, 0, sizeof(addr));
if (remote) {
if (getpeername(sock, (struct sockaddr *)&addr, &addrlen) != 0)
return NULL;
} else {
if (getsockname(sock, (struct sockaddr *)&addr, &addrlen) != 0)
return NULL;
}
/* Work around Linux IPv6 weirdness */
if (addr.ss_family == AF_INET6) {
addrlen = sizeof(struct sockaddr_in6);
ipv64_normalise_mapped(&addr, &addrlen);
}
switch (addr.ss_family) {
case AF_INET:
case AF_INET6:
/* Get the address in ascii. */
if ((r = getnameinfo((struct sockaddr *)&addr, addrlen, ntop,
sizeof(ntop), NULL, 0, flags)) != 0) {
error("%s: getnameinfo %d failed: %s", __func__,
flags, ssh_gai_strerror(r));
return NULL;
}
return xstrdup(ntop);
case AF_UNIX:
/* Get the Unix domain socket path. */
return xstrdup(((struct sockaddr_un *)&addr)->sun_path);
default:
/* We can't look up remote Unix domain sockets. */
return NULL;
}
}
char *
get_peer_ipaddr(int sock)
{
char *p;
if ((p = get_socket_address(sock, 1, NI_NUMERICHOST)) != NULL)
return p;
return xstrdup("UNKNOWN");
}
char *
get_local_ipaddr(int sock)
{
char *p;
if ((p = get_socket_address(sock, 0, NI_NUMERICHOST)) != NULL)
return p;
return xstrdup("UNKNOWN");
}
char *
get_local_name(int fd)
{
char *host, myname[NI_MAXHOST];
/* Assume we were passed a socket */
if ((host = get_socket_address(fd, 0, NI_NAMEREQD)) != NULL)
return host;
/* Handle the case where we were passed a pipe */
if (gethostname(myname, sizeof(myname)) == -1) {
verbose("%s: gethostname: %s", __func__, strerror(errno));
host = xstrdup("UNKNOWN");
} else {
host = xstrdup(myname);
}
return host;
}
/* 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];
int r;
/* 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));
return -1;
}
}
/* Work around Linux IPv6 weirdness */
if (from.ss_family == AF_INET6)
fromlen = sizeof(struct sockaddr_in6);
/* Non-inet sockets don't have a port number. */
if (from.ss_family != AF_INET && from.ss_family != AF_INET6)
return 0;
/* Return port number. */
if ((r = getnameinfo((struct sockaddr *)&from, fromlen, NULL, 0,
strport, sizeof(strport), NI_NUMERICSERV)) != 0)
fatal("%s: getnameinfo NI_NUMERICSERV failed: %s", __func__,
ssh_gai_strerror(r));
return atoi(strport);
}
int
get_peer_port(int sock)
{
return get_sock_port(sock, 0);
}
int
get_local_port(int sock)
{
return get_sock_port(sock, 1);
}
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