/* * Functions for looking up the remote name or addr of a socket. * * Copyright (C) 1992-2001 Andrew Tridgell * Copyright (C) 2001, 2002 Martin Pool * Copyright (C) 2002-2014 Wayne Davison * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 3 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License along * with this program; if not, visit the http://fsf.org website. */ /* * This file is now converted to use the new-style getaddrinfo() * interface, which supports IPv6 but is also supported on recent * IPv4-only machines. On systems that don't have that interface, we * emulate it using the KAME implementation. */ #include "rsync.h" static const char default_name[] = "UNKNOWN"; extern int am_server; /** * Return the IP addr of the client as a string **/ char *client_addr(int fd) { static char addr_buf[100]; static int initialised; struct sockaddr_storage ss; socklen_t length = sizeof ss; if (initialised) return addr_buf; initialised = 1; if (am_server) { /* daemon over --rsh mode */ char *env_str; strlcpy(addr_buf, "0.0.0.0", sizeof addr_buf); if ((env_str = getenv("REMOTE_HOST")) != NULL || (env_str = getenv("SSH_CONNECTION")) != NULL || (env_str = getenv("SSH_CLIENT")) != NULL || (env_str = getenv("SSH2_CLIENT")) != NULL) { char *p; strlcpy(addr_buf, env_str, sizeof addr_buf); /* Truncate the value to just the IP address. */ if ((p = strchr(addr_buf, ' ')) != NULL) *p = '\0'; } } else { client_sockaddr(fd, &ss, &length); getnameinfo((struct sockaddr *)&ss, length, addr_buf, sizeof addr_buf, NULL, 0, NI_NUMERICHOST); } return addr_buf; } static int get_sockaddr_family(const struct sockaddr_storage *ss) { return ((struct sockaddr *) ss)->sa_family; } /** * Return the DNS name of the client. * * The name is statically cached so that repeated lookups are quick, * so there is a limit of one lookup per customer. * * If anything goes wrong, including the name->addr->name check, then * we just use "UNKNOWN", so you can use that value in hosts allow * lines. * * After translation from sockaddr to name we do a forward lookup to * make sure nobody is spoofing PTR records. **/ char *client_name(int fd) { static char name_buf[100]; static char port_buf[100]; static int initialised; struct sockaddr_storage ss; socklen_t ss_len; if (initialised) return name_buf; strlcpy(name_buf, default_name, sizeof name_buf); initialised = 1; memset(&ss, 0, sizeof ss); if (am_server) { /* daemon over --rsh mode */ char *addr = client_addr(fd); struct addrinfo hint, *answer; int err; if (strcmp(addr, "0.0.0.0") == 0) return name_buf; memset(&hint, 0, sizeof hint); #ifdef AI_NUMERICHOST hint.ai_flags = AI_NUMERICHOST; #endif hint.ai_socktype = SOCK_STREAM; if ((err = getaddrinfo(addr, NULL, &hint, &answer)) != 0) { rprintf(FLOG, "malformed address %s: %s\n", addr, gai_strerror(err)); return name_buf; } switch (answer->ai_family) { case AF_INET: ss_len = sizeof (struct sockaddr_in); memcpy(&ss, answer->ai_addr, ss_len); break; #ifdef INET6 case AF_INET6: ss_len = sizeof (struct sockaddr_in6); memcpy(&ss, answer->ai_addr, ss_len); break; #endif default: exit_cleanup(RERR_SOCKETIO); } freeaddrinfo(answer); } else { ss_len = sizeof ss; client_sockaddr(fd, &ss, &ss_len); } if (lookup_name(fd, &ss, ss_len, name_buf, sizeof name_buf, port_buf, sizeof port_buf) == 0) check_name(fd, &ss, name_buf, sizeof name_buf); return name_buf; } /** * Get the sockaddr for the client. * * If it comes in as an ipv4 address mapped into IPv6 format then we * convert it back to a regular IPv4. **/ void client_sockaddr(int fd, struct sockaddr_storage *ss, socklen_t *ss_len) { memset(ss, 0, sizeof *ss); if (getpeername(fd, (struct sockaddr *) ss, ss_len)) { /* FIXME: Can we really not continue? */ rsyserr(FLOG, errno, "getpeername on fd%d failed", fd); exit_cleanup(RERR_SOCKETIO); } #ifdef INET6 if (get_sockaddr_family(ss) == AF_INET6 && IN6_IS_ADDR_V4MAPPED(&((struct sockaddr_in6 *)ss)->sin6_addr)) { /* OK, so ss is in the IPv6 family, but it is really * an IPv4 address: something like * "::ffff:10.130.1.2". If we use it as-is, then the * reverse lookup might fail or perhaps something else * bad might happen. So instead we convert it to an * equivalent address in the IPv4 address family. */ struct sockaddr_in6 sin6; struct sockaddr_in *sin; memcpy(&sin6, ss, sizeof sin6); sin = (struct sockaddr_in *)ss; memset(sin, 0, sizeof *sin); sin->sin_family = AF_INET; *ss_len = sizeof (struct sockaddr_in); #ifdef HAVE_SOCKADDR_IN_LEN sin->sin_len = *ss_len; #endif sin->sin_port = sin6.sin6_port; /* There is a macro to extract the mapped part * (IN6_V4MAPPED_TO_SINADDR ?), but it does not seem * to be present in the Linux headers. */ memcpy(&sin->sin_addr, &sin6.sin6_addr.s6_addr[12], sizeof sin->sin_addr); } #endif } /** * Look up a name from @p ss into @p name_buf. * * @param fd file descriptor for client socket. **/ int lookup_name(int fd, const struct sockaddr_storage *ss, socklen_t ss_len, char *name_buf, size_t name_buf_size, char *port_buf, size_t port_buf_size) { int name_err; /* reverse lookup */ name_err = getnameinfo((struct sockaddr *) ss, ss_len, name_buf, name_buf_size, port_buf, port_buf_size, NI_NAMEREQD | NI_NUMERICSERV); if (name_err != 0) { strlcpy(name_buf, default_name, name_buf_size); rprintf(FLOG, "name lookup failed for %s: %s\n", client_addr(fd), gai_strerror(name_err)); return name_err; } return 0; } /** * Compare an addrinfo from the resolver to a sockinfo. * * Like strcmp, returns 0 for identical. **/ int compare_addrinfo_sockaddr(const struct addrinfo *ai, const struct sockaddr_storage *ss) { int ss_family = get_sockaddr_family(ss); const char fn[] = "compare_addrinfo_sockaddr"; if (ai->ai_family != ss_family) { rprintf(FLOG, "%s: response family %d != %d\n", fn, ai->ai_family, ss_family); return 1; } /* The comparison method depends on the particular AF. */ if (ss_family == AF_INET) { const struct sockaddr_in *sin1, *sin2; sin1 = (const struct sockaddr_in *) ss; sin2 = (const struct sockaddr_in *) ai->ai_addr; return memcmp(&sin1->sin_addr, &sin2->sin_addr, sizeof sin1->sin_addr); } #ifdef INET6 if (ss_family == AF_INET6) { const struct sockaddr_in6 *sin1, *sin2; sin1 = (const struct sockaddr_in6 *) ss; sin2 = (const struct sockaddr_in6 *) ai->ai_addr; if (ai->ai_addrlen < sizeof (struct sockaddr_in6)) { rprintf(FLOG, "%s: too short sockaddr_in6; length=%d\n", fn, (int)ai->ai_addrlen); return 1; } if (memcmp(&sin1->sin6_addr, &sin2->sin6_addr, sizeof sin1->sin6_addr)) return 1; #ifdef HAVE_SOCKADDR_IN6_SCOPE_ID if (sin1->sin6_scope_id != sin2->sin6_scope_id) return 1; #endif return 0; } #endif /* INET6 */ /* don't know */ return 1; } /** * Do a forward lookup on @p name_buf and make sure it corresponds to * @p ss -- otherwise we may be being spoofed. If we suspect we are, * then we don't abort the connection but just emit a warning, and * change @p name_buf to be "UNKNOWN". * * We don't do anything with the service when checking the name, * because it doesn't seem that it could be spoofed in any way, and * getaddrinfo on random service names seems to cause problems on AIX. **/ int check_name(int fd, const struct sockaddr_storage *ss, char *name_buf, size_t name_buf_size) { struct addrinfo hints, *res, *res0; int error; int ss_family = get_sockaddr_family(ss); memset(&hints, 0, sizeof hints); hints.ai_family = ss_family; hints.ai_flags = AI_CANONNAME; hints.ai_socktype = SOCK_STREAM; error = getaddrinfo(name_buf, NULL, &hints, &res0); if (error) { rprintf(FLOG, "forward name lookup for %s failed: %s\n", name_buf, gai_strerror(error)); strlcpy(name_buf, default_name, name_buf_size); return error; } /* Given all these results, we expect that one of them will be * the same as ss. The comparison is a bit complicated. */ for (res = res0; res; res = res->ai_next) { if (!compare_addrinfo_sockaddr(res, ss)) break; /* OK, identical */ } if (!res0) { /* We hit the end of the list without finding an * address that was the same as ss. */ rprintf(FLOG, "no known address for \"%s\": " "spoofed address?\n", name_buf); strlcpy(name_buf, default_name, name_buf_size); } else if (res == NULL) { /* We hit the end of the list without finding an * address that was the same as ss. */ rprintf(FLOG, "%s is not a known address for \"%s\": " "spoofed address?\n", client_addr(fd), name_buf); strlcpy(name_buf, default_name, name_buf_size); } freeaddrinfo(res0); return 0; }