X-Git-Url: http://andersk.mit.edu/gitweb/openssh.git/blobdiff_plain/e7c0f9d591754e0c5512aa3cb5543dbb4e45605b..0752feb375b298fc4190d2b016e79f69b751b1a5:/canohost.c diff --git a/canohost.c b/canohost.c index 009b5253..22b19bb9 100644 --- a/canohost.c +++ b/canohost.c @@ -1,233 +1,426 @@ +/* $OpenBSD: canohost.c,v 1.65 2009/05/27 06:31:25 andreas Exp $ */ /* + * Author: Tatu Ylonen + * Copyright (c) 1995 Tatu Ylonen , 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". + */ -canohost.c +#include "includes.h" -Author: Tatu Ylonen +#include +#include -Copyright (c) 1995 Tatu Ylonen , Espoo, Finland - All rights reserved +#include +#include -Created: Sun Jul 2 17:52:22 1995 ylo +#include +#include +#include +#include +#include +#include +#include -Functions for returning the canonical host name of the remote site. +#include "xmalloc.h" +#include "packet.h" +#include "log.h" +#include "canohost.h" +#include "misc.h" -*/ +static void check_ip_options(int, char *); +static char *canonical_host_ip = NULL; +static int cached_port = -1; -#include "includes.h" -RCSID("$Id$"); +/* + * Return the canonical name of the host at the other end of the socket. The + * caller should free the returned string with xfree. + */ -#include "packet.h" -#include "xmalloc.h" -#include "ssh.h" - -/* 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) -{ - struct sockaddr_in from; - int fromlen, i; - struct hostent *hp; - char name[MAXHOSTNAMELEN]; - - /* 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(); - } - - /* Map the IP address to a host name. */ - hp = gethostbyaddr((char *)&from.sin_addr, sizeof(struct in_addr), - from.sin_family); - if (hp) - { - /* Got host name, find canonic host name. */ - if (strchr(hp->h_name, '.') != 0) - strlcpy(name, hp->h_name, sizeof(name)); - else if (hp->h_aliases != 0 - && hp->h_aliases[0] != 0 - && strchr(hp->h_aliases[0], '.') != 0) - strlcpy(name, hp->h_aliases[0], sizeof(name)); - else - strlcpy(name, hp->h_name, sizeof(name)); - - /* 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]); - - /* 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). */ - hp = gethostbyname(name); - if (!hp) - { - log("reverse mapping checking gethostbyname for %.700s failed - POSSIBLE BREAKIN ATTEMPT!", name); - strlcpy(name, inet_ntoa(from.sin_addr), sizeof name); - goto check_ip_options; +static char * +get_remote_hostname(int sock, int use_dns) +{ + 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(sock, (struct sockaddr *)&from, &fromlen) < 0) { + debug("getpeername failed: %.100s", strerror(errno)); + cleanup_exit(255); } - /* Look for the address from the list of addresses. */ - for (i = 0; hp->h_addr_list[i]; i++) - if (memcmp(hp->h_addr_list[i], &from.sin_addr, sizeof(from.sin_addr)) - == 0) - break; - /* If we reached the end of the list, the address was not there. */ - if (!hp->h_addr_list[i]) - { - /* 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!", - inet_ntoa(from.sin_addr), name); - strlcpy(name, inet_ntoa(from.sin_addr), sizeof name); - goto check_ip_options; + + if (from.ss_family == AF_INET) + check_ip_options(sock, ntop); + + ipv64_normalise_mapped(&from, &fromlen); + + if (from.ss_family == AF_INET6) + fromlen = sizeof(struct sockaddr_in6); + + if (getnameinfo((struct sockaddr *)&from, fromlen, ntop, sizeof(ntop), + NULL, 0, NI_NUMERICHOST) != 0) + fatal("get_remote_hostname: getnameinfo NI_NUMERICHOST failed"); + + if (!use_dns) + return xstrdup(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. */ + return xstrdup(ntop); } - /* Address was found for the host name. We accept the host name. */ - } - else - { - /* Host name not found. Use ascii representation of the address. */ - strlcpy(name, inet_ntoa(from.sin_addr), sizeof name); - log("Could not reverse map address %.100s.", name); - } - - check_ip_options: - - /* 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. */ - { - unsigned char options[200], *ucp; - char text[1024], *cp; - int option_size, ipproto; - struct protoent *ip; - - if ((ip = getprotobyname("ip")) != NULL) - ipproto = ip->p_proto; - else - ipproto = IPPROTO_IP; - option_size = sizeof(options); - if (getsockopt(0, ipproto, IP_OPTIONS, (char *)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", - inet_ntoa(from.sin_addr), text); - packet_disconnect("Connection from %.100s with IP options:%.800s", - inet_ntoa(from.sin_addr), text); - } - } - - return xstrdup(name); -} - -static char *canonical_host_name = NULL; -static char *canonical_host_ip = NULL; -/* 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. */ + /* + * 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 xstrdup(ntop); + } + + /* + * 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] = (char)tolower(name[i]); + /* + * 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 - POSSIBLE BREAK-IN ATTEMPT!", name, ntop); + 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. */ + logit("Address %.100s maps to %.600s, but this does not " + "map back to the address - POSSIBLE BREAK-IN 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 sock, char *ipaddr) +{ +#ifdef IP_OPTIONS + u_char options[200]; + char text[sizeof(options) * 3 + 1]; + socklen_t option_size; + u_int i; + int ipproto; + struct protoent *ip; + + if ((ip = getprotobyname("ip")) != NULL) + ipproto = ip->p_proto; + else + ipproto = IPPROTO_IP; + option_size = sizeof(options); + if (getsockopt(sock, 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]); + fatal("Connection from %.100s with IP options:%.800s", + ipaddr, text); + } +#endif /* IP_OPTIONS */ +} + +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(addr, 0, sizeof(*a4)); -const char *get_canonical_hostname() + a4->sin_family = AF_INET; + *len = sizeof(*a4); + memcpy(&a4->sin_addr, &inaddr, sizeof(inaddr)); + a4->sin_port = port; +} + +/* + * 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 use_dns) { - /* Check if we have previously retrieved this same name. */ - if (canonical_host_name != NULL) - return canonical_host_name; + char *host; + static char *canonical_host_name = NULL; + static char *remote_ip = NULL; + + /* Check if we have previously retrieved name with same option. */ + if (use_dns && canonical_host_name != NULL) + return canonical_host_name; + if (!use_dns && remote_ip != NULL) + return remote_ip; + + /* Get the real hostname if socket; otherwise return UNKNOWN. */ + if (packet_connection_is_on_socket()) + host = get_remote_hostname(packet_get_connection_in(), use_dns); + else + host = "UNKNOWN"; + + if (use_dns) + canonical_host_name = host; + else + remote_ip = host; + return host; +} + +/* + * 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; + } - /* Get the real hostname if socket; otherwise return UNKNOWN. */ - if (packet_get_connection_in() == packet_get_connection_out()) - canonical_host_name = get_remote_hostname(packet_get_connection_in()); - else - canonical_host_name = xstrdup("UNKNOWN"); + /* Work around Linux IPv6 weirdness */ + if (addr.ss_family == AF_INET6) + addrlen = sizeof(struct sockaddr_in6); - return canonical_host_name; + ipv64_normalise_mapped(&addr, &addrlen); + + /* Get the address in ascii. */ + if ((r = getnameinfo((struct sockaddr *)&addr, addrlen, ntop, + sizeof(ntop), NULL, 0, flags)) != 0) { + error("get_socket_address: getnameinfo %d failed: %s", flags, + ssh_gai_strerror(r)); + return NULL; + } + return xstrdup(ntop); } -/* Returns the IP-address of the remote host as a string. The returned - string need not be freed. */ +char * +get_peer_ipaddr(int sock) +{ + char *p; + + if ((p = get_socket_address(sock, 1, NI_NUMERICHOST)) != NULL) + return p; + return xstrdup("UNKNOWN"); +} -const char *get_remote_ipaddr() +char * +get_local_ipaddr(int sock) { - struct sockaddr_in from; - int fromlen, socket; + char *p; - /* Check if we have previously retrieved this same name. */ - if (canonical_host_ip != NULL) - return canonical_host_ip; + if ((p = get_socket_address(sock, 0, NI_NUMERICHOST)) != NULL) + return p; + return xstrdup("UNKNOWN"); +} - /* If not a socket, return UNKNOWN. */ - if (packet_get_connection_in() != packet_get_connection_out()) - { - canonical_host_ip = xstrdup("UNKNOWN"); - return canonical_host_ip; - } +char * +get_local_name(int sock) +{ + return get_socket_address(sock, 0, NI_NAMEREQD); +} - /* Get client socket. */ - socket = packet_get_connection_in(); +void +clear_cached_addr(void) +{ + if (canonical_host_ip != NULL) { + xfree(canonical_host_ip); + canonical_host_ip = NULL; + } + cached_port = -1; +} - /* 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(); - } +/* + * Returns the IP-address of the remote host as a string. The returned + * string must not be freed. + */ - /* Get the IP address in ascii. */ - canonical_host_ip = xstrdup(inet_ntoa(from.sin_addr)); +const char * +get_remote_ipaddr(void) +{ + /* 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) + cleanup_exit(255); + } else { + /* If not on socket, return UNKNOWN. */ + canonical_host_ip = xstrdup("UNKNOWN"); + } + } + return canonical_host_ip; +} - /* Return ip address string. */ - return canonical_host_ip; +const char * +get_remote_name_or_ip(u_int utmp_len, int use_dns) +{ + static const char *remote = ""; + if (utmp_len > 0) + remote = get_canonical_hostname(use_dns); + if (utmp_len == 0 || strlen(remote) > utmp_len) + remote = get_remote_ipaddr(); + return remote; } -/* Returns the port of the peer of the socket. */ +/* Returns the local/remote port for the socket. */ -int get_peer_port(int sock) +int +get_sock_port(int sock, int local) { - struct sockaddr_in from; - int fromlen; + 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; + } + } - /* Get IP address of client. */ - fromlen = sizeof(from); - memset(&from, 0, sizeof(from)); - if (getpeername(sock, (struct sockaddr *)&from, &fromlen) < 0) - { - debug("getpeername failed: %.100s", strerror(errno)); - fatal_cleanup(); - } + /* Work around Linux IPv6 weirdness */ + if (from.ss_family == AF_INET6) + fromlen = sizeof(struct sockaddr_in6); - /* Return port number. */ - return ntohs(from.sin_port); + /* Return port number. */ + if ((r = getnameinfo((struct sockaddr *)&from, fromlen, NULL, 0, + strport, sizeof(strport), NI_NUMERICSERV)) != 0) + fatal("get_sock_port: getnameinfo NI_NUMERICSERV failed: %s", + ssh_gai_strerror(r)); + return atoi(strport); } -/* Returns the port number of the remote host. */ +/* 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_remote_port() +int +get_peer_port(int sock) { - int socket; + return get_sock_port(sock, 0); +} - /* If the connection is not a socket, return 65535. This is intentionally - chosen to be an unprivileged port number. */ - if (packet_get_connection_in() != packet_get_connection_out()) - return 65535; +int +get_remote_port(void) +{ + /* Cache to avoid getpeername() on a dead connection */ + if (cached_port == -1) + cached_port = get_port(0); - /* Get client socket. */ - socket = packet_get_connection_in(); + return cached_port; +} - /* Get and return the peer port number. */ - return get_peer_port(socket); +int +get_local_port(void) +{ + return get_port(1); }