/* authd/providers/opm.c - small open proxy monitor * Copyright (c) 2016 Elizabeth Myers * * Permission to use, copy, modify, and/or distribute this software for any * purpose with or without fee is hereby granted, provided that the above * copyright notice and this permission notice is present in all copies. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. */ #include "rb_lib.h" #include "stdinc.h" #include "setup.h" #include "authd.h" #include "notice.h" #include "provider.h" #define OPM_READSIZE 128 typedef enum protocol_t { PROTO_NONE, PROTO_SOCKS4, PROTO_SOCKS5, } protocol_t; struct opm_lookup { rb_dlink_list scans; /* List of scans */ }; struct opm_proxy { char note[16]; protocol_t proto; uint16_t port; rb_dlink_node node; }; struct opm_scan { struct auth_client *auth; struct opm_proxy *proxy; rb_fde_t *F; /* fd for scan */ rb_dlink_node node; }; struct opm_listener { char ip[HOSTIPLEN]; uint16_t port; struct rb_sockaddr_storage addr; rb_fde_t *F; }; /* Proxies that we scan for */ static rb_dlink_list proxy_scanners; static ACCB accept_opm; static PF read_opm_reply; static CNCB socks4_connected; static CNCB socks5_connected; static void opm_cancel(struct auth_client *auth); static bool create_listener(const char *ip, uint16_t port); static int opm_timeout = 10; static bool opm_enable = false; #define LISTEN_IPV4 0 #define LISTEN_IPV6 1 /* IPv4 and IPv6 */ static struct opm_listener listeners[2]; static inline protocol_t get_protocol_from_string(const char *string) { if(strcasecmp(string, "socks4") == 0) return PROTO_SOCKS4; else if(strcasecmp(string, "socks5") == 0) return PROTO_SOCKS5; else return PROTO_NONE; } static inline struct opm_proxy * find_proxy_scanner(protocol_t proto, uint16_t port) { rb_dlink_node *ptr; RB_DLINK_FOREACH(ptr, proxy_scanners.head) { struct opm_proxy *proxy = ptr->data; if(proxy->proto == proto && proxy->port == port) return proxy; } return NULL; } static void read_opm_reply(rb_fde_t *F, void *data) { rb_dlink_node *ptr; struct auth_client *auth = data; struct opm_lookup *lookup; char readbuf[OPM_READSIZE]; ssize_t len; if(auth == NULL || (lookup = auth->data[PROVIDER_OPM]) == NULL) { rb_close(F); return; } if((len = rb_read(F, readbuf, sizeof(readbuf))) < 0 && rb_ignore_errno(errno)) { rb_setselect(F, RB_SELECT_READ, read_opm_reply, auth); return; } else if(len <= 0) { /* Dead */ rb_close(F); return; } RB_DLINK_FOREACH(ptr, proxy_scanners.head) { struct opm_proxy *proxy = ptr->data; if(strncmp(proxy->note, readbuf, sizeof(readbuf)) == 0) { rb_dlink_node *ptr, *nptr; /* Cancel outstanding lookups */ RB_DLINK_FOREACH_SAFE(ptr, nptr, lookup->scans.head) { struct opm_scan *scan = ptr->data; rb_close(scan->F); rb_free(scan); } /* No longer needed, client is going away */ rb_free(lookup); reject_client(auth, PROVIDER_OPM, readbuf, "Open proxy detected"); break; } } rb_close(F); } static void accept_opm(rb_fde_t *F, int status, struct sockaddr *addr, rb_socklen_t len, void *data) { struct auth_client *auth = NULL; struct opm_listener *listener = data; struct rb_sockaddr_storage localaddr; unsigned int llen = sizeof(struct rb_sockaddr_storage); rb_dictionary_iter iter; if(status != 0 || listener == NULL) { rb_close(F); return; } if(getsockname(rb_get_fd(F), (struct sockaddr *)&localaddr, &llen)) { /* This can happen if the client goes away after accept */ rb_close(F); return; } /* Correlate connection with client(s) */ RB_DICTIONARY_FOREACH(auth, &iter, auth_clients) { if(GET_SS_FAMILY(&auth->c_addr) != GET_SS_FAMILY(&localaddr)) continue; /* Compare the addresses */ switch(GET_SS_FAMILY(&localaddr)) { case AF_INET: { struct sockaddr_in *s = (struct sockaddr_in *)&localaddr, *c = (struct sockaddr_in *)&auth->c_addr; if(s->sin_addr.s_addr == c->sin_addr.s_addr) { /* Match... check if it's real */ rb_setselect(F, RB_SELECT_READ, read_opm_reply, auth); return; } break; } #ifdef RB_IPV6 case AF_INET6: { struct sockaddr_in6 *s = (struct sockaddr_in6 *)&localaddr, *c = (struct sockaddr_in6 *)&auth->c_addr; if(IN6_ARE_ADDR_EQUAL(&s->sin6_addr, &c->sin6_addr)) { rb_setselect(F, RB_SELECT_READ, read_opm_reply, auth); return; } break; } #endif default: warn_opers(L_CRIT, "OPM: unknown address type in listen function"); exit(EX_PROVIDER_ERROR); } } /* We don't care about the socket if we get here */ rb_close(F); } /* Scanners */ static void socks4_connected(rb_fde_t *F, int error, void *data) { struct opm_scan *scan = data; struct opm_lookup *lookup; struct auth_client *auth; uint8_t sendbuf[9]; /* Size we're building */ uint8_t *c = sendbuf; ssize_t ret; if(scan == NULL || (auth = scan->auth) == NULL || (lookup = auth->data[PROVIDER_OPM]) == NULL) return; if(error || !opm_enable) goto end; memcpy(c, "\x04\x01", 2); c += 2; /* Socks version 4, connect command */ switch(GET_SS_FAMILY(&auth->c_addr)) { case AF_INET: if(listeners[LISTEN_IPV4].F == NULL) /* They cannot respond to us */ goto end; memcpy(c, &(((struct sockaddr_in *)&listeners[LISTEN_IPV4].addr)->sin_port), 2); c += 2; /* Port */ memcpy(c, &(((struct sockaddr_in *)&listeners[LISTEN_IPV4].addr)->sin_addr.s_addr), 4); c += 4; /* Address */ break; #ifdef RB_IPV6 case AF_INET6: /* socks4 doesn't support IPv6 */ #endif default: goto end; } *c = '\x00'; /* No userid */ /* Send header */ if(rb_write(scan->F, sendbuf, sizeof(sendbuf)) < 0) goto end; /* Send note */ if(rb_write(scan->F, scan->proxy->note, strlen(scan->proxy->note) + 1) < 0) goto end; end: rb_close(scan->F); rb_dlinkDelete(&scan->node, &lookup->scans); rb_free(scan); } static void socks5_connected(rb_fde_t *F, int error, void *data) { struct opm_scan *scan = data; struct opm_lookup *lookup; struct opm_listener *listener; struct auth_client *auth; uint8_t sendbuf[25]; /* Size we're building */ uint8_t *c = sendbuf; ssize_t ret; if(scan == NULL || (auth = scan->auth) == NULL || (lookup = auth->data[PROVIDER_OPM]) == NULL) return; if(error || !opm_enable) goto end; /* Build the version header and socks request * version header (3 bytes): version, number of auth methods, auth type (0 for none) * connect req (3 bytes): version, command (1 = connect), reserved (0) */ memcpy(c, "\x05\x01\x00\x05\x01\x00", 6); c += 6; switch(GET_SS_FAMILY(&auth->c_addr)) { case AF_INET: listener = &listeners[LISTEN_IPV4]; if(!listener->F) goto end; *(c++) = '\x01'; /* Address type (1 = IPv4) */ memcpy(c, &(((struct sockaddr_in *)&listener->addr)->sin_addr.s_addr), 4); c += 4;/* Address */ memcpy(c, &(((struct sockaddr_in *)&listener->addr)->sin_port), 2); c += 2; /* Port */ break; #ifdef RB_IPV6 case AF_INET6: listener = &listeners[LISTEN_IPV6]; if(!listener->F) goto end; *(c++) = '\x04'; /* Address type (4 = IPv6) */ memcpy(c, ((struct sockaddr_in6 *)&listener->addr)->sin6_addr.s6_addr, 16); c += 16; /* Address */ memcpy(c, &(((struct sockaddr_in6 *)&listener->addr)->sin6_port), 2); c += 2; /* Port */ break; #endif default: goto end; } /* Send header */ if(rb_write(scan->F, sendbuf, (size_t)(sendbuf - c)) <= 0) goto end; /* Now the note in a separate write */ if(rb_write(scan->F, scan->proxy->note, strlen(scan->proxy->note) + 1) <= 0) goto end; end: rb_close(scan->F); rb_dlinkDelete(&scan->node, &lookup->scans); rb_free(scan); } /* Establish connections */ static inline void establish_connection(struct auth_client *auth, struct opm_proxy *proxy) { struct opm_lookup *lookup = auth->data[PROVIDER_OPM]; struct opm_listener *listener; struct opm_scan *scan = rb_malloc(sizeof(struct opm_scan)); struct rb_sockaddr_storage c_a, l_a; int opt = 1; CNCB *callback; switch(proxy->proto) { case PROTO_SOCKS4: #ifdef RB_IPV6 if(GET_SS_FAMILY(&auth->c_addr) == AF_INET6) { rb_free(scan); return; } #endif callback = socks4_connected; break; case PROTO_SOCKS5: callback = socks5_connected; break; default: return; } #ifdef RB_IPV6 if(GET_SS_FAMILY(&auth->c_addr) == AF_INET6) listener = &listeners[LISTEN_IPV6]; else #endif listener = &listeners[LISTEN_IPV4]; c_a = auth->c_addr; /* Client */ l_a = listener->addr; /* Listener */ scan->auth = auth; scan->proxy = proxy; if((scan->F = rb_socket(GET_SS_FAMILY(&auth->c_addr), SOCK_STREAM, 0, proxy->note)) == NULL) { warn_opers(L_CRIT, "OPM: could not create OPM socket (proto %s): %s", proxy->note, strerror(errno)); rb_free(scan); return; } /* Disable Nagle's algorithim - buffering could affect scans */ (void)setsockopt(rb_get_fd(scan->F), IPPROTO_TCP, TCP_NODELAY, (char *)&opt, sizeof(opt)); SET_SS_PORT(&l_a, 0); SET_SS_PORT(&c_a, htons(proxy->port)); rb_dlinkAdd(scan, &scan->node, &lookup->scans); rb_connect_tcp(scan->F, (struct sockaddr *)&c_a, (struct sockaddr *)&l_a, GET_SS_LEN(&l_a), callback, scan, opm_timeout); } static bool create_listener(const char *ip, uint16_t port) { struct auth_client *auth; struct opm_listener *listener; struct rb_sockaddr_storage addr; rb_dictionary_iter iter; rb_fde_t *F; int opt = 1; if(!rb_inet_pton_sock(ip, (struct sockaddr *)&addr)) { warn_opers(L_CRIT, "OPM: got a bad listener: %s:%hu", ip, port); exit(EX_PROVIDER_ERROR); } #ifdef RB_IPV6 if(GET_SS_FAMILY(&addr) == AF_INET6) { struct sockaddr_in6 *a1, *a2; listener = &listeners[LISTEN_IPV6]; a1 = (struct sockaddr_in6 *)&addr; a2 = (struct sockaddr_in6 *)&listener->addr; if(IN6_ARE_ADDR_EQUAL(&a1->sin6_addr, &a2->sin6_addr) && GET_SS_PORT(&addr) == GET_SS_PORT(&listener->addr) && listener->F != NULL) { /* Listener already exists */ return false; } } else #endif { struct sockaddr_in *a1, *a2; listener = &listeners[LISTEN_IPV4]; a1 = (struct sockaddr_in *)&addr; a2 = (struct sockaddr_in *)&listener->addr; if(a1->sin_addr.s_addr == a2->sin_addr.s_addr && GET_SS_PORT(&addr) == GET_SS_PORT(&listener->addr) && listener->F != NULL) { /* Listener already exists */ return false; } } if((F = rb_socket(GET_SS_FAMILY(&addr), SOCK_STREAM, 0, "OPM listener socket")) == NULL) { /* This shouldn't fail, or we have big problems... */ warn_opers(L_CRIT, "OPM: cannot create socket: %s", strerror(errno)); exit(EX_PROVIDER_ERROR); } if(setsockopt(rb_get_fd(F), SOL_SOCKET, SO_REUSEADDR, (char *)&opt, sizeof(opt))) { /* This shouldn't fail either... */ warn_opers(L_CRIT, "OPM: cannot set options on socket: %s", strerror(errno)); exit(EX_PROVIDER_ERROR); } /* Set up ports for binding */ #ifdef RB_IPV6 if(GET_SS_FAMILY(&addr) == AF_INET6) ((struct sockaddr_in6 *)&addr)->sin6_port = htons(port); else #endif ((struct sockaddr_in *)&addr)->sin_port = htons(port); if(bind(rb_get_fd(F), (struct sockaddr *)&addr, GET_SS_LEN(&addr))) { /* Shit happens, let's not cripple authd over /this/ since it could be user error */ warn_opers(L_WARN, "OPM: cannot bind on socket: %s", strerror(errno)); rb_close(F); return false; } if(rb_listen(F, SOMAXCONN, false)) /* deferred accept could interfere with detection */ { /* Again, could be user error */ warn_opers(L_WARN, "OPM: cannot listen on socket: %s", strerror(errno)); rb_close(F); return false; } /* From this point forward we assume we have a listener */ if(listener->F != NULL) /* Close old listener */ rb_close(listener->F); listener->F = F; /* Cancel clients that may be on old listener * XXX - should rescan clients that need it */ RB_DICTIONARY_FOREACH(auth, &iter, auth_clients) { opm_cancel(auth); } /* Copy data */ rb_strlcpy(listener->ip, ip, sizeof(listener->ip)); listener->port = port; listener->addr = addr; opm_enable = true; /* Implicitly set this to true for now if we have a listener */ rb_accept_tcp(listener->F, NULL, accept_opm, listener); return true; } static void opm_destroy(void) { struct auth_client *auth; rb_dictionary_iter iter; /* Nuke all opm lookups */ RB_DICTIONARY_FOREACH(auth, &iter, auth_clients) { opm_cancel(auth); } } static bool opm_start(struct auth_client *auth) { rb_dlink_node *ptr; struct opm_lookup *lookup = rb_malloc(sizeof(struct opm_lookup)); if(!opm_enable || !rb_dlink_list_length(&proxy_scanners)) { notice_client(auth->cid, "*** Proxy scanning disabled, not scanning"); return true; } auth->data[PROVIDER_OPM] = lookup = rb_malloc(sizeof(struct opm_lookup)); auth->timeout[PROVIDER_OPM] = rb_current_time() + opm_timeout; RB_DLINK_FOREACH(ptr, proxy_scanners.head) { struct opm_proxy *proxy = ptr->data; establish_connection(auth, proxy); } notice_client(auth->cid, "*** Scanning for open proxies..."); set_provider_on(auth, PROVIDER_OPM); return true; } static void opm_cancel(struct auth_client *auth) { struct opm_lookup *lookup = auth->data[PROVIDER_OPM]; if(lookup != NULL) { rb_dlink_node *ptr, *nptr; notice_client(auth->cid, "*** Did not detect open proxies"); RB_DLINK_FOREACH_SAFE(ptr, nptr, lookup->scans.head) { struct opm_scan *scan = ptr->data; rb_close(scan->F); rb_free(scan); } rb_free(lookup); provider_done(auth, PROVIDER_OPM); } } static void add_conf_opm_timeout(const char *key __unused, int parc __unused, const char **parv) { int timeout = atoi(parv[0]); if(timeout < 0) { warn_opers(L_CRIT, "opm: opm timeout < 0 (value: %d)", timeout); return; } opm_timeout = timeout; } static void set_opm_enabled(const char *key __unused, int parc __unused, const char **parv) { bool enable = (*parv[0] == '1'); if(!enable) { if(listeners[LISTEN_IPV4].F != NULL || listeners[LISTEN_IPV6].F != NULL) { struct auth_client *auth; rb_dictionary_iter iter; /* Close the listening socket */ if(listeners[LISTEN_IPV4].F != NULL) rb_close(listeners[LISTEN_IPV4].F); if(listeners[LISTEN_IPV6].F != NULL) rb_close(listeners[LISTEN_IPV6].F); listeners[LISTEN_IPV4].F = listeners[LISTEN_IPV6].F = NULL; RB_DICTIONARY_FOREACH(auth, &iter, auth_clients) { opm_cancel(auth); } } } else { if(listeners[LISTEN_IPV4].ip[0] != '\0' && listeners[LISTEN_IPV4].port != 0) { lrb_assert(listeners[LISTEN_IPV4].F == NULL); /* Pre-configured IP/port, just re-establish */ create_listener(listeners[LISTEN_IPV4].ip, listeners[LISTEN_IPV4].port); } if(listeners[LISTEN_IPV6].ip[0] != '\0' && listeners[LISTEN_IPV6].port != 0) { lrb_assert(listeners[LISTEN_IPV6].F == NULL); /* Pre-configured IP/port, just re-establish */ create_listener(listeners[LISTEN_IPV6].ip, listeners[LISTEN_IPV6].port); } } opm_enable = enable; } static void set_opm_listener(const char *key __unused, int parc __unused, const char **parv) { const char *ip = parv[0]; int iport = atoi(parv[1]); if(iport > 65535 || iport <= 0) { warn_opers(L_CRIT, "OPM: got a bad listener: %s:%s", parv[0], parv[1]); exit(EX_PROVIDER_ERROR); } create_listener(ip, (uint16_t)iport); } static void create_opm_scanner(const char *key __unused, int parc __unused, const char **parv) { int iport = atoi(parv[1]); struct opm_proxy *proxy = rb_malloc(sizeof(struct opm_proxy)); if(iport <= 0 || iport > 65535) { warn_opers(L_CRIT, "OPM: got a bad scanner: %s (port %s)", parv[0], parv[1]); exit(EX_PROVIDER_ERROR); } proxy->port = (uint16_t)iport; switch((proxy->proto = get_protocol_from_string(parv[0]))) { case PROTO_SOCKS4: snprintf(proxy->note, sizeof(proxy->note), "socks4:%hu", proxy->port); break; case PROTO_SOCKS5: snprintf(proxy->note, sizeof(proxy->note), "socks5:%hu", proxy->port); break; default: warn_opers(L_CRIT, "OPM: got an unknown proxy type: %s (port %hu)", parv[0], proxy->port); exit(EX_PROVIDER_ERROR); } if(find_proxy_scanner(proxy->proto, proxy->port) != NULL) { warn_opers(L_CRIT, "OPM: got a duplicate scanner: %s (port %hu)", parv[0], proxy->port); exit(EX_PROVIDER_ERROR); } rb_dlinkAdd(proxy, &proxy->node, &proxy_scanners); } static void delete_opm_scanner(const char *key __unused, int parc __unused, const char **parv) { struct auth_client *auth; struct opm_proxy *proxy; protocol_t proto = get_protocol_from_string(parv[0]); int iport = atoi(parv[1]); rb_dictionary_iter iter; if(iport <= 0 || iport > 65535) { warn_opers(L_CRIT, "OPM: got a bad scanner to delete: %s (port %s)", parv[0], parv[1]); exit(EX_PROVIDER_ERROR); } if(proto == PROTO_NONE) { warn_opers(L_CRIT, "OPM: got an unknown proxy type to delete: %s (port %d)", parv[0], iport); exit(EX_PROVIDER_ERROR); } if((proxy = find_proxy_scanner(proto, (uint16_t)iport)) == NULL) { warn_opers(L_CRIT, "OPM: cannot find proxy to delete: %s (port %d)", parv[0], iport); exit(EX_PROVIDER_ERROR); } /* Abort remaining clients on this scanner */ RB_DICTIONARY_FOREACH(auth, &iter, auth_clients) { rb_dlink_node *ptr; struct opm_lookup *lookup = auth->data[PROVIDER_OPM]; if(lookup == NULL) continue; RB_DLINK_FOREACH(ptr, lookup->scans.head) { struct opm_scan *scan = ptr->data; if(scan->proxy->port == proxy->port && scan->proxy->proto == proxy->proto) { /* Match */ rb_dlinkDelete(&scan->node, &lookup->scans); rb_free(scan); if(!rb_dlink_list_length(&lookup->scans)) opm_cancel(auth); break; } } } rb_dlinkDelete(&proxy->node, &proxy_scanners); rb_free(proxy); } static void delete_opm_scanner_all(const char *key __unused, int parc __unused, const char **parv __unused) { struct auth_client *auth; rb_dlink_node *ptr, *nptr; rb_dictionary_iter iter; RB_DLINK_FOREACH_SAFE(ptr, nptr, proxy_scanners.head) { rb_free(ptr->data); rb_dlinkDelete(ptr, &proxy_scanners); } RB_DICTIONARY_FOREACH(auth, &iter, auth_clients) { opm_cancel(auth); } } struct auth_opts_handler opm_options[] = { { "opm_timeout", 1, add_conf_opm_timeout }, { "opm_enabled", 1, set_opm_enabled }, { "opm_listener", 2, set_opm_listener }, { "opm_scanner", 2, create_opm_scanner }, { "opm_scanner_del", 2, delete_opm_scanner }, { "opm_scanner_del_all", 0, delete_opm_scanner_all }, { NULL, 0, NULL }, }; struct auth_provider opm_provider = { .id = PROVIDER_OPM, .destroy = opm_destroy, .start = opm_start, .cancel = opm_cancel, .timeout = opm_cancel, .opt_handlers = opm_options, };