X-Git-Url: http://andersk.mit.edu/gitweb/openssh.git/blobdiff_plain/a22aff1fb16cbb68775742f7b60c5bfa3f72c903..HEAD:/canohost.c diff --git a/canohost.c b/canohost.c index 6d36dd11..ef94d915 100644 --- a/canohost.c +++ b/canohost.c @@ -1,3 +1,4 @@ +/* $OpenBSD: canohost.c,v 1.66 2010/01/13 01:20:20 dtucker Exp $ */ /* * Author: Tatu Ylonen * Copyright (c) 1995 Tatu Ylonen , Espoo, Finland @@ -12,157 +13,200 @@ */ #include "includes.h" -RCSID("$OpenBSD: canohost.c,v 1.16 2000/10/21 17:04:22 markus Exp $"); -#include "packet.h" +#include +#include + +#include +#include + +#include +#include +#include +#include +#include +#include +#include +#include + #include "xmalloc.h" -#include "ssh.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; /* * 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) +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[MAXHOSTNAMELEN]; - char ntop[NI_MAXHOST], ntop2[NI_MAXHOST]; + 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) { + if (getpeername(sock, (struct sockaddr *)&from, &fromlen) < 0) { debug("getpeername failed: %.100s", strerror(errno)); - fatal_cleanup(); + cleanup_exit(255); } -#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(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) + 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) { - /* 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]); - - /* - * 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); - strlcpy(name, ntop, sizeof name); - goto check_ip_options; - } - /* 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); - strlcpy(name, ntop, sizeof name); - goto check_ip_options; - } - /* 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, ntop, sizeof name); - log("Could not reverse map address %.100s.", name); + NULL, 0, NI_NAMEREQD) != 0) { + /* Host name not found. Use ip address. */ + return xstrdup(ntop); } -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. + * 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 */ - /* IP options -- IPv4 only */ - if (from.ss_family == AF_INET) { - unsigned 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, (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", - ntop, text); - packet_disconnect("Connection from %.100s with IP options:%.800s", - ntop, text); - } + 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)); + + 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 @@ -170,67 +214,156 @@ check_ip_options: */ const char * -get_canonical_hostname() +get_canonical_hostname(int use_dns) { + char *host; static char *canonical_host_name = NULL; + static char *remote_ip = NULL; - /* Check if we have previously retrieved this same name. */ - if (canonical_host_name != 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()) - canonical_host_name = get_remote_hostname(packet_get_connection_in()); + host = get_remote_hostname(packet_get_connection_in(), use_dns); else - canonical_host_name = xstrdup("UNKNOWN"); + host = "UNKNOWN"; - return canonical_host_name; + if (use_dns) + canonical_host_name = host; + else + remote_ip = host; + return host; } /* - * Returns the IP-address of the remote host as a string. The returned - * string must not be freed. + * Returns the local/remote IP-address/hostname of socket as a string. + * The returned string must be freed. */ - -const char * -get_remote_ipaddr() +static char * +get_socket_address(int sock, int remote, int flags) { - static char *canonical_host_ip = NULL; - struct sockaddr_storage from; - socklen_t fromlen; - int socket; + struct sockaddr_storage addr; + socklen_t addrlen; char ntop[NI_MAXHOST]; + int r; - /* Check whether we have chached the name. */ - if (canonical_host_ip != NULL) - return canonical_host_ip; + /* Get IP address of client. */ + addrlen = sizeof(addr); + memset(&addr, 0, sizeof(addr)); - /* If not a socket, return UNKNOWN. */ - if (!packet_connection_is_on_socket()) { - canonical_host_ip = xstrdup("UNKNOWN"); - return canonical_host_ip; + if (remote) { + if (getpeername(sock, (struct sockaddr *)&addr, &addrlen) + < 0) + return NULL; + } else { + if (getsockname(sock, (struct sockaddr *)&addr, &addrlen) + < 0) + return NULL; } - /* Get client socket. */ - socket = packet_get_connection_in(); - /* 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(); + /* Work around Linux IPv6 weirdness */ + if (addr.ss_family == AF_INET6) + addrlen = sizeof(struct sockaddr_in6); + + 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; } - /* Get the IP address in ascii. */ - if (getnameinfo((struct sockaddr *)&from, fromlen, ntop, sizeof(ntop), - NULL, 0, NI_NUMERICHOST) != 0) - fatal("get_remote_hostname: getnameinfo NI_NUMERICHOST failed"); + return xstrdup(ntop); +} + +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("get_local_name: gethostname: %s", strerror(errno)); + } else { + host = xstrdup(myname); + } + + return host; +} + +void +clear_cached_addr(void) +{ + if (canonical_host_ip != NULL) { + xfree(canonical_host_ip); + canonical_host_ip = NULL; + } + cached_port = -1; +} - canonical_host_ip = xstrdup(ntop); +/* + * Returns the IP-address of the remote host as a string. The returned + * string must not be freed. + */ - /* Return ip address string. */ +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; } +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 local/remote port for the socket. */ int @@ -239,6 +372,7 @@ 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); @@ -249,21 +383,27 @@ get_sock_port(int sock, int local) return 0; } } else { - if (getpeername(sock, (struct sockaddr *) & from, &fromlen) < 0) { + if (getpeername(sock, (struct sockaddr *)&from, &fromlen) < 0) { debug("getpeername failed: %.100s", strerror(errno)); - fatal_cleanup(); + return -1; } } + + /* Work around Linux IPv6 weirdness */ + if (from.ss_family == AF_INET6) + fromlen = sizeof(struct sockaddr_in6); + /* 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"); + 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 remote/local port number for the current connection. */ -int +static int get_port(int local) { /* @@ -284,13 +424,17 @@ get_peer_port(int sock) } int -get_remote_port() +get_remote_port(void) { - return get_port(0); + /* Cache to avoid getpeername() on a dead connection */ + if (cached_port == -1) + cached_port = get_port(0); + + return cached_port; } int -get_local_port() +get_local_port(void) { return get_port(1); }