/* Based on ipsvd utilities written by Gerrit Pape * which are released into public domain by the author. * Homepage: http://smarden.sunsite.dk/ipsvd/ * * Copyright (C) 2007 Denis Vlasenko. * * Licensed under GPLv2, see file LICENSE in this tarball for details. */ /* Based on ipsvd ipsvd-0.12.1. This tcpsvd accepts all options * which are supported by one from ipsvd-0.12.1, but not all are * functional. See help text at the end of this file for details. * * Code inside "#ifdef SSLSVD" is for sslsvd and is currently unused. * Code inside #if 0" is parts of original tcpsvd which are not implemented * for busyboxed version. * * Output of verbose mode matches original (modulo bugs and * unimplemented stuff). Unnatural splitting of IP and PORT * is retained (personally I prefer one-value "IP:PORT" notation - * it is a natural string representation of struct sockaddr_XX). * * TCPORIGDST{IP,PORT} is busybox-specific addition */ #include #include /* wants */ #include "busybox.h" #include "ipsvd_perhost.h" #ifdef SSLSVD #include "matrixSsl.h" #include "ssl_io.h" #endif static unsigned max_per_host; /* originally in ipsvd_check.c */ static unsigned cur_per_host; static unsigned verbose; static unsigned cnum; static unsigned cmax = 30; /* Must match getopt32 in main! */ enum { OPT_c = (1 << 0), OPT_C = (1 << 1), OPT_i = (1 << 2), OPT_x = (1 << 3), OPT_u = (1 << 4), OPT_l = (1 << 5), OPT_E = (1 << 6), OPT_b = (1 << 7), OPT_h = (1 << 8), OPT_p = (1 << 9), OPT_t = (1 << 10), OPT_v = (1 << 11), OPT_V = (1 << 12), OPT_U = (1 << 13), /* from here: sslsvd only */ OPT_slash = (1 << 14), OPT_Z = (1 << 15), OPT_K = (1 << 16), }; static void connection_status(void) { printf("%s: info: status %u/%u\n", applet_name, cnum, cmax); } static void sig_term_handler(int sig) { if (verbose) printf("%s: info: sigterm received, exit\n", applet_name); exit(0); } static void sig_child_handler(int sig) { int wstat; int pid; while ((pid = wait_nohang(&wstat)) > 0) { if (max_per_host) ipsvd_perhost_remove(pid); if (cnum) cnum--; if (verbose) { /* Little bloated, but tries to give accurate info * how child exited. Makes easier to spot segfaulting * children etc... */ unsigned e = 0; const char *cause = "?exit"; if (WIFEXITED(wstat)) { cause++; e = WEXITSTATUS(wstat); } else if (WIFSIGNALED(wstat)) { cause = "signal"; e = WTERMSIG(wstat); } printf("%s: info: end %d %s %d\n", applet_name, pid, cause, e); } } if (verbose) connection_status(); } int tcpsvd_main(int argc, char **argv); int tcpsvd_main(int argc, char **argv) { char *str_c, *str_C, *str_b, *str_t; char *user; struct hcc *hccp; const char *instructs; char *msg_per_host = NULL; unsigned len_per_host = len_per_host; /* gcc */ int need_hostnames, need_remote_ip; int pid; int sock; int conn; unsigned backlog = 20; union { struct sockaddr sa; struct sockaddr_in sin; USE_FEATURE_IPV6(struct sockaddr_in6 sin6;) } sock_adr; socklen_t sockadr_size; uint16_t local_port = local_port; uint16_t remote_port; char *local_hostname = NULL; char *remote_hostname = (char*)""; /* "" used if no -h */ char *local_ip = local_ip; char *remote_ip = NULL; //unsigned iscdb = 0; /* = option_mask32 & OPT_x (TODO) */ //unsigned long timeout = 0; #ifndef SSLSVD struct bb_uidgid_t ugid; #endif /* 3+ args, -i at most once, -p implies -h, -v is counter */ opt_complementary = "-3:?:i--i:ph:vv"; #ifdef SSLSVD getopt32(argc, argv, "c:C:i:x:u:l:Eb:hpt:vU:/:Z:K:", &str_c, &str_C, &instructs, &instructs, &user, &local_hostname, &str_b, &str_t, &ssluser, &root, &cert, &key, &verbose ); #else getopt32(argc, argv, "c:C:i:x:u:l:Eb:hpt:v", &str_c, &str_C, &instructs, &instructs, &user, &local_hostname, &str_b, &str_t, &verbose ); #endif if (option_mask32 & OPT_c) cmax = xatou_range(str_c, 1, INT_MAX); if (option_mask32 & OPT_C) { /* -C n[:message] */ max_per_host = bb_strtou(str_C, &str_C, 10); if (str_C[0]) { if (str_C[0] != ':') bb_show_usage(); msg_per_host = str_C + 1; len_per_host = strlen(msg_per_host); } } if (max_per_host > cmax) max_per_host = cmax; if (option_mask32 & OPT_u) { if (!get_uidgid(&ugid, user, 1)) bb_error_msg_and_die("unknown user/group: %s", user); } if (option_mask32 & OPT_b) backlog = xatou(str_b); // if (option_mask32 & OPT_t) timeout = xatou(str_t); #ifdef SSLSVD if (option_mask32 & OPT_U) ssluser = (char*)optarg; break; if (option_mask32 & OPT_slash) root = (char*)optarg; break; if (option_mask32 & OPT_Z) cert = (char*)optarg; break; if (option_mask32 & OPT_K) key = (char*)optarg; break; #endif argv += optind; if (!argv[0][0] || LONE_CHAR(argv[0], '0')) argv[0] = (char*)"0.0.0.0"; setlinebuf(stdout); need_hostnames = verbose || !(option_mask32 & OPT_E); need_remote_ip = max_per_host || need_hostnames; #ifdef SSLSVD sslser = user; client = 0; if ((getuid() == 0) && !(option_mask32 & OPT_u)) { xfunc_exitcode = 100; bb_error_msg_and_die("fatal: -U ssluser must be set when running as root"); } if (option_mask32 & OPT_u) if (!uidgid_get(&sslugid, ssluser, 1)) { if (errno) { xfunc_exitcode = 100; bb_perror_msg_and_die("fatal: cannot get user/group: %s", ssluser); } xfunc_exitcode = 111; bb_error_msg_and_die("fatal: unknown user/group '%s'", ssluser); } if (!cert) cert = "./cert.pem"; if (!key) key = cert; if (matrixSslOpen() < 0) fatal("cannot initialize ssl"); if (matrixSslReadKeys(&keys, cert, key, 0, ca) < 0) { if (client) fatal("cannot read cert, key, or ca file"); fatal("cannot read cert or key file"); } if (matrixSslNewSession(&ssl, keys, 0, SSL_FLAGS_SERVER) < 0) fatal("cannot create ssl session"); #endif sig_block(SIGCHLD); signal(SIGCHLD, sig_child_handler); signal(SIGTERM, sig_term_handler); signal(SIGPIPE, SIG_IGN); if (max_per_host) ipsvd_perhost_init(cmax); local_port = bb_lookup_port(argv[1], "tcp", 0); sock = create_and_bind_stream_or_die(argv[0], local_port); xlisten(sock, backlog); /* ndelay_off(sock); - it is the default I think? */ #ifndef SSLSVD if (option_mask32 & OPT_u) { /* drop permissions */ xsetgid(ugid.gid); xsetuid(ugid.uid); } #endif bb_sanitize_stdio(); /* fd# 1,2 must be opened */ close(0); if (verbose) { /* we do it only for ":port" cosmetics... oh well */ len_and_sockaddr *lsa = xhost2sockaddr(argv[0], local_port); char *addr = xmalloc_sockaddr2dotted(&lsa->sa, lsa->len); printf("%s: info: listening on %s", applet_name, addr); free(addr); #ifndef SSLSVD if (option_mask32 & OPT_u) printf(", uid %u, gid %u", (unsigned)ugid.uid, (unsigned)ugid.gid); #endif puts(", starting"); } /* The rest is a main accept() loop */ again: hccp = NULL; while (cnum >= cmax) sig_pause(); /* wait for any signal (expecting SIGCHLD) */ sockadr_size = sizeof(sock_adr); sig_unblock(SIGCHLD); conn = accept(sock, &sock_adr.sa, &sockadr_size); sig_block(SIGCHLD); if (conn == -1) { if (errno != EINTR) bb_perror_msg("accept"); goto again; } if (max_per_host) { /* we drop connection immediately if cur_per_host > max_per_host * (minimizing load under SYN flood) */ free(remote_ip); remote_ip = xmalloc_sockaddr2dotted_noport(&sock_adr.sa, sockadr_size); cur_per_host = ipsvd_perhost_add(remote_ip, max_per_host, &hccp); if (cur_per_host > max_per_host) { /* ipsvd_perhost_add detected that max is exceeded * (and did not store us in connection table) */ if (msg_per_host) { ndelay_on(conn); /* don't test for errors */ write(conn, msg_per_host, len_per_host); } close(conn); goto again; } } cnum++; if (verbose) connection_status(); pid = fork(); if (pid == -1) { bb_perror_msg("fork"); close(conn); goto again; } if (pid != 0) { /* parent */ close(conn); if (hccp) hccp->pid = pid; goto again; } /* Child: prepare env, log, and exec prog */ close(sock); if (!max_per_host && need_remote_ip) remote_ip = xmalloc_sockaddr2dotted_noport(&sock_adr.sa, sizeof(sock_adr)); /* else it is already done */ remote_port = get_nport(&sock_adr.sa); remote_port = ntohs(remote_port); if (verbose) { pid = getpid(); printf("%s: info: pid %d from %s\n", applet_name, pid, remote_ip); } if (need_hostnames && (option_mask32 & OPT_h)) { remote_hostname = xmalloc_sockaddr2host(&sock_adr.sa, sizeof(sock_adr)); if (!remote_hostname) { bb_error_msg("warning: cannot look up hostname for %s", remote_ip); remote_hostname = (char*)""; } } sockadr_size = sizeof(sock_adr); /* Errors ignored (I'm not paranoid enough to imagine kernel * which doesn't know local ip) */ getsockname(conn, &sock_adr.sa, &sockadr_size); if (need_hostnames) { local_ip = xmalloc_sockaddr2dotted_noport(&sock_adr.sa, sockadr_size); local_port = get_nport(&sock_adr.sa); local_port = ntohs(local_port); if (!local_hostname) { local_hostname = xmalloc_sockaddr2host_noport(&sock_adr.sa, sockadr_size); if (!local_hostname) bb_error_msg_and_die("cannot look up local hostname for %s", local_ip); } } if (!(option_mask32 & OPT_E)) { /* setup ucspi env */ /* Extract "original" destination addr:port * from Linux firewall. Useful when you redirect * an outbond connection to local handler, and it needs * to know where it originally tried to connect */ sockadr_size = sizeof(sock_adr); if (getsockopt(conn, SOL_IP, SO_ORIGINAL_DST, &sock_adr.sa, &sockadr_size) == 0) { char *ip = xmalloc_sockaddr2dotted_noport(&sock_adr.sa, sockadr_size); unsigned port = get_nport(&sock_adr.sa); port = ntohs(port); xsetenv("TCPORIGDSTIP", ip); xsetenv("TCPORIGDSTPORT", utoa(port)); free(ip); } xsetenv("PROTO", "TCP"); xsetenv("TCPLOCALIP", local_ip); xsetenv("TCPLOCALPORT", utoa(local_port)); xsetenv("TCPLOCALHOST", local_hostname); xsetenv("TCPREMOTEIP", remote_ip); xsetenv("TCPREMOTEPORT", utoa(remote_port)); if (option_mask32 & OPT_h) { xsetenv("TCPREMOTEHOST", remote_hostname); } xsetenv("TCPREMOTEINFO", ""); /* additional */ if (cur_per_host > 0) xsetenv("TCPCONCURRENCY", utoa(cur_per_host)); } #if 0 if (instructs) { ac = ipsvd_check(iscdb, &inst, &match, (char*)instructs, remote_ip, remote_hostname, timeout); if (ac == -1) drop2("cannot check inst", remote_ip); if (ac == IPSVD_ERR) drop2("cannot read", (char*)instructs); } else ac = IPSVD_DEFAULT; #endif if (max_per_host && verbose) printf("%s: info: concurrency %u %s %u/%u\n", applet_name, pid, remote_ip, cur_per_host, max_per_host); if (verbose) { printf("%s: info: start %u %s:%s :%s:%s:%u\n", applet_name, pid, local_hostname, local_ip, remote_hostname, remote_ip, (unsigned)remote_port); #if 0 switch(ac) { case IPSVD_DENY: printf("deny "); break; case IPSVD_DEFAULT: case IPSVD_INSTRUCT: printf("start "); break; case IPSVD_EXEC: printf("exec "); break; } ... if (instructs) { printf(" "); if (iscdb) { printf((char*)instructs); printf("/"); } outfix(match.s); if(inst.s && inst.len && (verbose > 1)) { printf(": "); printf(&inst); } } printf("\n"); #endif } #if 0 if (ac == IPSVD_DENY) { close(conn); _exit(100); } if (ac == IPSVD_EXEC) { args[0] = "/bin/sh"; args[1] = "-c"; args[2] = inst.s; args[3] = 0; run = args; } else run = argv + 2; /* below: we use argv+2 (was using run) */ #endif xmove_fd(conn, 0); dup2(0, 1); signal(SIGTERM, SIG_DFL); signal(SIGPIPE, SIG_DFL); signal(SIGCHLD, SIG_DFL); sig_unblock(SIGCHLD); argv += 2; #ifdef SSLSVD strcpy(id, utoa(pid); ssl_io(0, argv); #else BB_EXECVP(argv[0], argv); #endif bb_perror_msg_and_die("exec '%s'", argv[0]); } /* tcpsvd [-hpEvv] [-c n] [-C n:msg] [-b n] [-u user] [-l name] [-i dir|-x cdb] [ -t sec] host port prog tcpsvd creates a TCP/IP socket, binds it to the address host:port, and listens on the socket for incoming connections. On each incoming connection, tcpsvd conditionally runs a program, with standard input reading from the socket, and standard output writing to the socket, to handle this connection. tcpsvd keeps listening on the socket for new connections, and can handle multiple connections simultaneously. tcpsvd optionally checks for special instructions depending on the IP address or hostname of the client that initiated the connection, see ipsvd-instruct(5). host host either is a hostname, or a dotted-decimal IP address, or 0. If host is 0, tcpsvd accepts connections to any local IP address. * busybox accepts IPv6 addresses and host:port pairs too In this case second parameter is ignored port tcpsvd accepts connections to host:port. port may be a name from /etc/services or a number. prog prog consists of one or more arguments. For each connection, tcpsvd normally runs prog, with file descriptor 0 reading from the network, and file descriptor 1 writing to the network. By default it also sets up TCP-related environment variables, see tcp-environ(5) -i dir read instructions for handling new connections from the instructions directory dir. See ipsvd-instruct(5) for details. * ignored by busyboxed version -x cdb read instructions for handling new connections from the constant database cdb. The constant database normally is created from an instructions directory by running ipsvd-cdb(8). * ignored by busyboxed version -t sec timeout. This option only takes effect if the -i option is given. While checking the instructions directory, check the time of last access of the file that matches the clients address or hostname if any, discard and remove the file if it wasn't accessed within the last sec seconds; tcpsvd does not discard or remove a file if the user's write permission is not set, for those files the timeout is disabled. Default is 0, which means that the timeout is disabled. * ignored by busyboxed version -l name local hostname. Do not look up the local hostname in DNS, but use name as hostname. This option must be set if tcpsvd listens on port 53 to avoid loops. -u user[:group] drop permissions. Switch user ID to user's UID, and group ID to user's primary GID after creating and binding to the socket. If user is followed by a colon and a group name, the group ID is switched to the GID of group instead. All supplementary groups are removed. -c n concurrency. Handle up to n connections simultaneously. Default is 30. If there are n connections active, tcpsvd defers acceptance of a new connection until an active connection is closed. -C n[:msg] per host concurrency. Allow only up to n connections from the same IP address simultaneously. If there are n active connections from one IP address, new incoming connections from this IP address are closed immediately. If n is followed by :msg, the message msg is written to the client if possible, before closing the connection. By default msg is empty. See ipsvd-instruct(5) for supported escape sequences in msg. For each accepted connection, the current per host concurrency is available through the environment variable TCPCONCURRENCY. n and msg can be overwritten by ipsvd(7) instructions, see ipsvd-instruct(5). By default tcpsvd doesn't keep track of connections. -h Look up the client's hostname in DNS. -p paranoid. After looking up the client's hostname in DNS, look up the IP addresses in DNS for that hostname, and forget about the hostname if none of the addresses match the client's IP address. You should set this option if you use hostname based instructions. The -p option implies the -h option. * ignored by busyboxed version -b n backlog. Allow a backlog of approximately n TCP SYNs. On some systems n is silently limited. Default is 20. -E no special environment. Do not set up TCP-related environment variables. -v verbose. Print verbose messsages to standard output. -vv more verbose. Print more verbose messages to standard output. * no difference between -v and -vv in busyboxed version */