/* * This module determines the type of socket (datagram, stream), the client * socket address and port, the server socket address and port. In addition, * it provides methods to map a transport address to a printable host name * or address. Socket address information results are in static memory. * * The result from the hostname lookup method is STRING_PARANOID when a host * pretends to have someone elses name, or when a host name is available but * could not be verified. * * When lookup or conversion fails the result is set to STRING_UNKNOWN. * * Diagnostics are reported through syslog(3). * * Author: Wietse Venema, Eindhoven University of Technology, The Netherlands. * * $FreeBSD$ */ #ifndef lint static char sccsid[] = "@(#) socket.c 1.15 97/03/21 19:27:24"; #endif /* System libraries. */ #include #include #include #include #include #include #include #include #ifndef INET6 extern char *inet_ntoa(); #endif /* Local stuff. */ #include "tcpd.h" /* Forward declarations. */ static void sock_sink(int); #ifdef APPEND_DOT /* * Speed up DNS lookups by terminating the host name with a dot. Should be * done with care. The speedup can give problems with lookups from sources * that lack DNS-style trailing dot magic, such as local files or NIS maps. */ static struct hostent *gethostbyname_dot(name) char *name; { char dot_name[MAXHOSTNAMELEN + 1]; /* * Don't append dots to unqualified names. Such names are likely to come * from local hosts files or from NIS. */ if (strchr(name, '.') == 0 || strlen(name) >= MAXHOSTNAMELEN - 1) { return (gethostbyname(name)); } else { sprintf(dot_name, "%s.", name); return (gethostbyname(dot_name)); } } #define gethostbyname gethostbyname_dot #endif /* sock_host - look up endpoint addresses and install conversion methods */ void sock_host(request) struct request_info *request; { #ifdef INET6 static struct sockaddr_storage client; static struct sockaddr_storage server; #else static struct sockaddr_in client; static struct sockaddr_in server; #endif int len; char buf[BUFSIZ]; int fd = request->fd; sock_methods(request); /* * Look up the client host address. Hal R. Brand * suggested how to get the client host info in case of UDP connections: * peek at the first message without actually looking at its contents. We * really should verify that client.sin_family gets the value AF_INET, * but this program has already caused too much grief on systems with * broken library code. */ len = sizeof(client); if (getpeername(fd, (struct sockaddr *) & client, &len) < 0) { request->sink = sock_sink; len = sizeof(client); if (recvfrom(fd, buf, sizeof(buf), MSG_PEEK, (struct sockaddr *) & client, &len) < 0) { tcpd_warn("can't get client address: %m"); return; /* give up */ } #ifdef really_paranoid memset(buf, 0, sizeof(buf)); #endif } #ifdef INET6 request->client->sin = (struct sockaddr *)&client; #else request->client->sin = &client; #endif /* * Determine the server binding. This is used for client username * lookups, and for access control rules that trigger on the server * address or name. */ len = sizeof(server); if (getsockname(fd, (struct sockaddr *) & server, &len) < 0) { tcpd_warn("getsockname: %m"); return; } #ifdef INET6 request->server->sin = (struct sockaddr *)&server; #else request->server->sin = &server; #endif } /* sock_hostaddr - map endpoint address to printable form */ void sock_hostaddr(host) struct host_info *host; { #ifdef INET6 struct sockaddr *sin = host->sin; int salen; if (!sin) return; #ifdef SIN6_LEN salen = sin->sa_len; #else salen = (sin->sa_family == AF_INET) ? sizeof(struct sockaddr_in) : sizeof(struct sockaddr_in6); #endif getnameinfo(sin, salen, host->addr, sizeof(host->addr), NULL, 0, NI_NUMERICHOST); #else struct sockaddr_in *sin = host->sin; if (sin != 0) STRN_CPY(host->addr, inet_ntoa(sin->sin_addr), sizeof(host->addr)); #endif } /* sock_hostname - map endpoint address to host name */ void sock_hostname(host) struct host_info *host; { #ifdef INET6 struct sockaddr *sin = host->sin; struct sockaddr_in sin4; struct addrinfo hints, *res, *res0 = NULL; int salen, alen, err = 1; char *ap = NULL, *rap, hname[NI_MAXHOST]; if (sin != NULL) { if (sin->sa_family == AF_INET6) { struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)sin; if (IN6_IS_ADDR_V4MAPPED(&sin6->sin6_addr)) { memset(&sin4, 0, sizeof(sin4)); #ifdef SIN6_LEN sin4.sin_len = sizeof(sin4); #endif sin4.sin_family = AF_INET; sin4.sin_port = sin6->sin6_port; sin4.sin_addr.s_addr = *(u_int32_t *)&sin6->sin6_addr.s6_addr[12]; sin = (struct sockaddr *)&sin4; } } switch (sin->sa_family) { case AF_INET: ap = (char *)&((struct sockaddr_in *)sin)->sin_addr; alen = sizeof(struct in_addr); salen = sizeof(struct sockaddr_in); break; case AF_INET6: ap = (char *)&((struct sockaddr_in6 *)sin)->sin6_addr; alen = sizeof(struct in6_addr); salen = sizeof(struct sockaddr_in6); break; default: break; } if (ap) err = getnameinfo(sin, salen, hname, sizeof(hname), NULL, 0, NI_NAMEREQD); } if (!err) { STRN_CPY(host->name, hname, sizeof(host->name)); /* reject numeric addresses */ memset(&hints, 0, sizeof(hints)); hints.ai_family = sin->sa_family; hints.ai_socktype = SOCK_STREAM; hints.ai_flags = AI_PASSIVE | AI_CANONNAME | AI_NUMERICHOST; if ((err = getaddrinfo(host->name, NULL, &hints, &res0)) == 0) { freeaddrinfo(res0); tcpd_warn("host name/name mismatch: " "reverse lookup results in non-FQDN %s", host->name); strcpy(host->name, paranoid); /* name is bad, clobber it */ } err = !err; } if (!err) { /* we are now sure that this is non-numeric */ /* * Verify that the address is a member of the address list returned * by gethostbyname(hostname). * * Verify also that gethostbyaddr() and gethostbyname() return the same * hostname, or rshd and rlogind may still end up being spoofed. * * On some sites, gethostbyname("localhost") returns "localhost.domain". * This is a DNS artefact. We treat it as a special case. When we * can't believe the address list from gethostbyname("localhost") * we're in big trouble anyway. */ memset(&hints, 0, sizeof(hints)); hints.ai_family = sin->sa_family; hints.ai_socktype = SOCK_STREAM; hints.ai_flags = AI_PASSIVE | AI_CANONNAME; if (getaddrinfo(host->name, NULL, &hints, &res0) != 0) { /* * Unable to verify that the host name matches the address. This * may be a transient problem or a botched name server setup. */ tcpd_warn("can't verify hostname: getaddrinfo(%s, %s) failed", host->name, (sin->sa_family == AF_INET) ? "AF_INET" : "AF_INET6"); } else if ((res0->ai_canonname == NULL || STR_NE(host->name, res0->ai_canonname)) && STR_NE(host->name, "localhost")) { /* * The gethostbyaddr() and gethostbyname() calls did not return * the same hostname. This could be a nameserver configuration * problem. It could also be that someone is trying to spoof us. */ tcpd_warn("host name/name mismatch: %s != %.*s", host->name, STRING_LENGTH, (res0->ai_canonname == NULL) ? "" : res0->ai_canonname); } else { /* * The address should be a member of the address list returned by * gethostbyname(). We should first verify that the h_addrtype * field is AF_INET, but this program has already caused too much * grief on systems with broken library code. */ for (res = res0; res; res = res->ai_next) { if (res->ai_family != sin->sa_family) continue; switch (res->ai_family) { case AF_INET: rap = (char *)&((struct sockaddr_in *)res->ai_addr)->sin_addr; break; case AF_INET6: /* need to check scope_id */ if (((struct sockaddr_in6 *)sin)->sin6_scope_id != ((struct sockaddr_in6 *)res->ai_addr)->sin6_scope_id) { continue; } rap = (char *)&((struct sockaddr_in6 *)res->ai_addr)->sin6_addr; break; default: continue; } if (memcmp(rap, ap, alen) == 0) { freeaddrinfo(res0); return; /* name is good, keep it */ } } /* * The host name does not map to the initial address. Perhaps * someone has messed up. Perhaps someone compromised a name * server. */ getnameinfo(sin, salen, hname, sizeof(hname), NULL, 0, NI_NUMERICHOST); tcpd_warn("host name/address mismatch: %s != %.*s", hname, STRING_LENGTH, (res0->ai_canonname == NULL) ? "" : res0->ai_canonname); } strcpy(host->name, paranoid); /* name is bad, clobber it */ if (res0) freeaddrinfo(res0); } #else /* INET6 */ struct sockaddr_in *sin = host->sin; struct hostent *hp; int i; /* * On some systems, for example Solaris 2.3, gethostbyaddr(0.0.0.0) does * not fail. Instead it returns "INADDR_ANY". Unfortunately, this does * not work the other way around: gethostbyname("INADDR_ANY") fails. We * have to special-case 0.0.0.0, in order to avoid false alerts from the * host name/address checking code below. */ if (sin != 0 && sin->sin_addr.s_addr != 0 && (hp = gethostbyaddr((char *) &(sin->sin_addr), sizeof(sin->sin_addr), AF_INET)) != 0) { STRN_CPY(host->name, hp->h_name, sizeof(host->name)); /* * Verify that the address is a member of the address list returned * by gethostbyname(hostname). * * Verify also that gethostbyaddr() and gethostbyname() return the same * hostname, or rshd and rlogind may still end up being spoofed. * * On some sites, gethostbyname("localhost") returns "localhost.domain". * This is a DNS artefact. We treat it as a special case. When we * can't believe the address list from gethostbyname("localhost") * we're in big trouble anyway. */ if ((hp = gethostbyname(host->name)) == 0) { /* * Unable to verify that the host name matches the address. This * may be a transient problem or a botched name server setup. */ tcpd_warn("can't verify hostname: gethostbyname(%s) failed", host->name); } else if (STR_NE(host->name, hp->h_name) && STR_NE(host->name, "localhost")) { /* * The gethostbyaddr() and gethostbyname() calls did not return * the same hostname. This could be a nameserver configuration * problem. It could also be that someone is trying to spoof us. */ tcpd_warn("host name/name mismatch: %s != %.*s", host->name, STRING_LENGTH, hp->h_name); } else { /* * The address should be a member of the address list returned by * gethostbyname(). We should first verify that the h_addrtype * field is AF_INET, but this program has already caused too much * grief on systems with broken library code. */ for (i = 0; hp->h_addr_list[i]; i++) { if (memcmp(hp->h_addr_list[i], (char *) &sin->sin_addr, sizeof(sin->sin_addr)) == 0) return; /* name is good, keep it */ } /* * The host name does not map to the initial address. Perhaps * someone has messed up. Perhaps someone compromised a name * server. */ tcpd_warn("host name/address mismatch: %s != %.*s", inet_ntoa(sin->sin_addr), STRING_LENGTH, hp->h_name); } strcpy(host->name, paranoid); /* name is bad, clobber it */ } #endif /* INET6 */ } /* sock_sink - absorb unreceived IP datagram */ static void sock_sink(int fd) { char buf[BUFSIZ]; #ifdef INET6 struct sockaddr_storage sin; #else struct sockaddr_in sin; #endif int size = sizeof(sin); /* * Eat up the not-yet received datagram. Some systems insist on a * non-zero source address argument in the recvfrom() call below. */ (void) recvfrom(fd, buf, sizeof(buf), 0, (struct sockaddr *) & sin, &size); }