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e3b60b524e
[authfd.c canohost.c clientloop.c dns.c dns.h includes.h] [monitor_fdpass.c nchan.c packet.c servconf.c sftp.c ssh-agent.c] [ssh-keyscan.c ssh.c sshconnect.h sshd.c sshlogin.h] move #include <sys/socket.h> out of includes.h
411 lines
10 KiB
C
411 lines
10 KiB
C
/* $OpenBSD: canohost.c,v 1.55 2006/07/08 21:47:12 stevesk Exp $ */
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/*
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* Author: Tatu Ylonen <ylo@cs.hut.fi>
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* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
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* All rights reserved
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* Functions for returning the canonical host name of the remote site.
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*
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* As far as I am concerned, the code I have written for this software
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* can be used freely for any purpose. Any derived versions of this
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* software must be clearly marked as such, and if the derived work is
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* incompatible with the protocol description in the RFC file, it must be
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* called by a name other than "ssh" or "Secure Shell".
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*/
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#include "includes.h"
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#include <sys/types.h>
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#include <sys/socket.h>
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#include <netinet/in.h>
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#include <ctype.h>
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#include "packet.h"
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#include "xmalloc.h"
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#include "log.h"
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#include "canohost.h"
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static void check_ip_options(int, char *);
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/*
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* Return the canonical name of the host at the other end of the socket. The
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* caller should free the returned string with xfree.
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*/
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static char *
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get_remote_hostname(int sock, int use_dns)
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{
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struct sockaddr_storage from;
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int i;
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socklen_t fromlen;
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struct addrinfo hints, *ai, *aitop;
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char name[NI_MAXHOST], ntop[NI_MAXHOST], ntop2[NI_MAXHOST];
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/* Get IP address of client. */
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fromlen = sizeof(from);
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memset(&from, 0, sizeof(from));
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if (getpeername(sock, (struct sockaddr *)&from, &fromlen) < 0) {
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debug("getpeername failed: %.100s", strerror(errno));
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cleanup_exit(255);
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}
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if (from.ss_family == AF_INET)
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check_ip_options(sock, ntop);
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ipv64_normalise_mapped(&from, &fromlen);
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if (from.ss_family == AF_INET6)
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fromlen = sizeof(struct sockaddr_in6);
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if (getnameinfo((struct sockaddr *)&from, fromlen, ntop, sizeof(ntop),
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NULL, 0, NI_NUMERICHOST) != 0)
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fatal("get_remote_hostname: getnameinfo NI_NUMERICHOST failed");
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if (!use_dns)
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return xstrdup(ntop);
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debug3("Trying to reverse map address %.100s.", ntop);
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/* Map the IP address to a host name. */
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if (getnameinfo((struct sockaddr *)&from, fromlen, name, sizeof(name),
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NULL, 0, NI_NAMEREQD) != 0) {
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/* Host name not found. Use ip address. */
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return xstrdup(ntop);
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}
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/*
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* if reverse lookup result looks like a numeric hostname,
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* someone is trying to trick us by PTR record like following:
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* 1.1.1.10.in-addr.arpa. IN PTR 2.3.4.5
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*/
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memset(&hints, 0, sizeof(hints));
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hints.ai_socktype = SOCK_DGRAM; /*dummy*/
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hints.ai_flags = AI_NUMERICHOST;
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if (getaddrinfo(name, "0", &hints, &ai) == 0) {
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logit("Nasty PTR record \"%s\" is set up for %s, ignoring",
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name, ntop);
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freeaddrinfo(ai);
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return xstrdup(ntop);
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}
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/*
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* Convert it to all lowercase (which is expected by the rest
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* of this software).
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*/
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for (i = 0; name[i]; i++)
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if (isupper(name[i]))
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name[i] = (char)tolower(name[i]);
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/*
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* Map it back to an IP address and check that the given
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* address actually is an address of this host. This is
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* necessary because anyone with access to a name server can
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* define arbitrary names for an IP address. Mapping from
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* name to IP address can be trusted better (but can still be
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* fooled if the intruder has access to the name server of
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* the domain).
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*/
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memset(&hints, 0, sizeof(hints));
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hints.ai_family = from.ss_family;
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hints.ai_socktype = SOCK_STREAM;
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if (getaddrinfo(name, NULL, &hints, &aitop) != 0) {
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logit("reverse mapping checking getaddrinfo for %.700s "
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"[%s] failed - POSSIBLE BREAK-IN ATTEMPT!", name, ntop);
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return xstrdup(ntop);
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}
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/* Look for the address from the list of addresses. */
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for (ai = aitop; ai; ai = ai->ai_next) {
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if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop2,
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sizeof(ntop2), NULL, 0, NI_NUMERICHOST) == 0 &&
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(strcmp(ntop, ntop2) == 0))
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break;
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}
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freeaddrinfo(aitop);
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/* If we reached the end of the list, the address was not there. */
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if (!ai) {
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/* Address not found for the host name. */
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logit("Address %.100s maps to %.600s, but this does not "
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"map back to the address - POSSIBLE BREAK-IN ATTEMPT!",
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ntop, name);
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return xstrdup(ntop);
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}
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return xstrdup(name);
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}
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/*
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* If IP options are supported, make sure there are none (log and
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* disconnect them if any are found). Basically we are worried about
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* source routing; it can be used to pretend you are somebody
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* (ip-address) you are not. That itself may be "almost acceptable"
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* under certain circumstances, but rhosts autentication is useless
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* if source routing is accepted. Notice also that if we just dropped
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* source routing here, the other side could use IP spoofing to do
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* rest of the interaction and could still bypass security. So we
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* exit here if we detect any IP options.
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*/
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/* IPv4 only */
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static void
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check_ip_options(int sock, char *ipaddr)
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{
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#ifdef IP_OPTIONS
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u_char options[200];
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char text[sizeof(options) * 3 + 1];
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socklen_t option_size;
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u_int i;
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int ipproto;
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struct protoent *ip;
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if ((ip = getprotobyname("ip")) != NULL)
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ipproto = ip->p_proto;
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else
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ipproto = IPPROTO_IP;
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option_size = sizeof(options);
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if (getsockopt(sock, ipproto, IP_OPTIONS, options,
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&option_size) >= 0 && option_size != 0) {
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text[0] = '\0';
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for (i = 0; i < option_size; i++)
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snprintf(text + i*3, sizeof(text) - i*3,
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" %2.2x", options[i]);
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fatal("Connection from %.100s with IP options:%.800s",
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ipaddr, text);
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}
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#endif /* IP_OPTIONS */
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}
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void
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ipv64_normalise_mapped(struct sockaddr_storage *addr, socklen_t *len)
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{
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struct sockaddr_in6 *a6 = (struct sockaddr_in6 *)addr;
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struct sockaddr_in *a4 = (struct sockaddr_in *)addr;
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struct in_addr inaddr;
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u_int16_t port;
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if (addr->ss_family != AF_INET6 ||
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!IN6_IS_ADDR_V4MAPPED(&a6->sin6_addr))
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return;
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debug3("Normalising mapped IPv4 in IPv6 address");
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memcpy(&inaddr, ((char *)&a6->sin6_addr) + 12, sizeof(inaddr));
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port = a6->sin6_port;
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memset(addr, 0, sizeof(*a4));
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a4->sin_family = AF_INET;
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*len = sizeof(*a4);
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memcpy(&a4->sin_addr, &inaddr, sizeof(inaddr));
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a4->sin_port = port;
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}
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/*
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* Return the canonical name of the host in the other side of the current
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* connection. The host name is cached, so it is efficient to call this
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* several times.
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*/
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const char *
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get_canonical_hostname(int use_dns)
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{
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char *host;
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static char *canonical_host_name = NULL;
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static char *remote_ip = NULL;
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/* Check if we have previously retrieved name with same option. */
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if (use_dns && canonical_host_name != NULL)
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return canonical_host_name;
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if (!use_dns && remote_ip != NULL)
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return remote_ip;
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/* Get the real hostname if socket; otherwise return UNKNOWN. */
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if (packet_connection_is_on_socket())
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host = get_remote_hostname(packet_get_connection_in(), use_dns);
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else
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host = "UNKNOWN";
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if (use_dns)
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canonical_host_name = host;
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else
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remote_ip = host;
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return host;
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}
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/*
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* Returns the local/remote IP-address/hostname of socket as a string.
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* The returned string must be freed.
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*/
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static char *
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get_socket_address(int sock, int remote, int flags)
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{
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struct sockaddr_storage addr;
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socklen_t addrlen;
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char ntop[NI_MAXHOST];
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int r;
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/* Get IP address of client. */
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addrlen = sizeof(addr);
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memset(&addr, 0, sizeof(addr));
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if (remote) {
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if (getpeername(sock, (struct sockaddr *)&addr, &addrlen)
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< 0)
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return NULL;
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} else {
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if (getsockname(sock, (struct sockaddr *)&addr, &addrlen)
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< 0)
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return NULL;
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}
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/* Work around Linux IPv6 weirdness */
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if (addr.ss_family == AF_INET6)
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addrlen = sizeof(struct sockaddr_in6);
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ipv64_normalise_mapped(&addr, &addrlen);
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/* Get the address in ascii. */
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if ((r = getnameinfo((struct sockaddr *)&addr, addrlen, ntop,
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sizeof(ntop), NULL, 0, flags)) != 0) {
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error("get_socket_address: getnameinfo %d failed: %s", flags,
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r == EAI_SYSTEM ? strerror(errno) : gai_strerror(r));
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return NULL;
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}
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return xstrdup(ntop);
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}
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char *
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get_peer_ipaddr(int sock)
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{
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char *p;
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if ((p = get_socket_address(sock, 1, NI_NUMERICHOST)) != NULL)
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return p;
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return xstrdup("UNKNOWN");
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}
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char *
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get_local_ipaddr(int sock)
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{
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char *p;
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if ((p = get_socket_address(sock, 0, NI_NUMERICHOST)) != NULL)
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return p;
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return xstrdup("UNKNOWN");
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}
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char *
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get_local_name(int sock)
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{
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return get_socket_address(sock, 0, NI_NAMEREQD);
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}
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/*
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* Returns the IP-address of the remote host as a string. The returned
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* string must not be freed.
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*/
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const char *
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get_remote_ipaddr(void)
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{
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static char *canonical_host_ip = NULL;
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/* Check whether we have cached the ipaddr. */
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if (canonical_host_ip == NULL) {
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if (packet_connection_is_on_socket()) {
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canonical_host_ip =
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get_peer_ipaddr(packet_get_connection_in());
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if (canonical_host_ip == NULL)
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cleanup_exit(255);
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} else {
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/* If not on socket, return UNKNOWN. */
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canonical_host_ip = xstrdup("UNKNOWN");
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}
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}
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return canonical_host_ip;
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}
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const char *
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get_remote_name_or_ip(u_int utmp_len, int use_dns)
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{
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static const char *remote = "";
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if (utmp_len > 0)
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remote = get_canonical_hostname(use_dns);
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if (utmp_len == 0 || strlen(remote) > utmp_len)
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remote = get_remote_ipaddr();
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return remote;
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}
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/* Returns the local/remote port for the socket. */
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static int
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get_sock_port(int sock, int local)
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{
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struct sockaddr_storage from;
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socklen_t fromlen;
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char strport[NI_MAXSERV];
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int r;
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/* Get IP address of client. */
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fromlen = sizeof(from);
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memset(&from, 0, sizeof(from));
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if (local) {
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if (getsockname(sock, (struct sockaddr *)&from, &fromlen) < 0) {
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error("getsockname failed: %.100s", strerror(errno));
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return 0;
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}
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} else {
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if (getpeername(sock, (struct sockaddr *)&from, &fromlen) < 0) {
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debug("getpeername failed: %.100s", strerror(errno));
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return -1;
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}
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}
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/* Work around Linux IPv6 weirdness */
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if (from.ss_family == AF_INET6)
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fromlen = sizeof(struct sockaddr_in6);
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/* Return port number. */
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if ((r = getnameinfo((struct sockaddr *)&from, fromlen, NULL, 0,
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strport, sizeof(strport), NI_NUMERICSERV)) != 0)
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fatal("get_sock_port: getnameinfo NI_NUMERICSERV failed: %s",
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r == EAI_SYSTEM ? strerror(errno) : gai_strerror(r));
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return atoi(strport);
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}
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/* Returns remote/local port number for the current connection. */
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static int
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get_port(int local)
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{
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/*
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* If the connection is not a socket, return 65535. This is
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* intentionally chosen to be an unprivileged port number.
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*/
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if (!packet_connection_is_on_socket())
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return 65535;
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/* Get socket and return the port number. */
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return get_sock_port(packet_get_connection_in(), local);
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}
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int
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get_peer_port(int sock)
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{
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return get_sock_port(sock, 0);
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}
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int
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get_remote_port(void)
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{
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static int port = -1;
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/* Cache to avoid getpeername() on a dead connection */
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if (port == -1)
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port = get_port(0);
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return port;
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}
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int
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get_local_port(void)
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{
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return get_port(1);
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}
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