X-Git-Url: https://git.distorted.org.uk/~mdw/fwd/blobdiff_plain/afd7451e40e07118103fcc81e3b635a164c545c4..b69a615b311fb4081d97ccee6cd13777bcf4d5ca:/fw.c diff --git a/fw.c b/fw.c index 04235d4..bf3e477 100644 --- a/fw.c +++ b/fw.c @@ -1,10 +1,10 @@ /* -*-c-*- * - * $Id: fw.c,v 1.2 1999/07/03 13:55:17 mdw Exp $ + * $Id$ * * Port forwarding thingy * - * (c) 1999 Mark Wooding + * (c) 1999 Straylight/Edgeware */ /*----- Licensing notice --------------------------------------------------* @@ -26,62 +26,398 @@ * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ -/*----- Revision history --------------------------------------------------* - * - * $Log: fw.c,v $ - * Revision 1.2 1999/07/03 13:55:17 mdw - * Various changes. Add configuration grammar to help text. Change to - * root directory and open syslog when forking into background. - * - * Revision 1.1.1.1 1999/07/01 08:56:23 mdw - * Initial revision. - * - */ - /*----- Header files ------------------------------------------------------*/ #include "config.h" +#include #include #include +#include +#include #include #include #include +#include #include #include +#include +#include + +#include +#include #include #include #include #include +#include #include -#include "acl.h" -#include "bres.h" #include "conf.h" +#include "endpt.h" +#include "exec.h" +#include "fattr.h" +#include "file.h" #include "fw.h" -#include "listener.h" +#include "privconn.h" #include "scan.h" +#include "socket.h" +#include "source.h" /*----- Global variables --------------------------------------------------*/ sel_state *sel; /* Multiplexor for nonblocking I/O */ -unsigned flags = 0; /* Global state flags */ -/*----- Main code ---------------------------------------------------------*/ +/*----- Static variables --------------------------------------------------*/ + +typedef struct conffile { + struct conffile *next; + char *name; +} conffile; + +static unsigned flags = 0; /* Global state flags */ +static unsigned active = 0; /* Number of active things */ +static conffile *conffiles = 0; /* List of configuration files */ + +#define FW_SYSLOG 1u +#define FW_QUIET 2u +#define FW_SET 4u + +/*----- Configuration parsing ---------------------------------------------*/ + +/* --- @parse@ --- * + * + * Arguments: @scanner *sc@ = pointer to scanner definition + * + * Returns: --- + * + * Use: Parses a configuration file from the scanner. + */ + +static source_ops *sources[] = + { &xsource_ops, &fsource_ops, &ssource_ops, 0 }; +static target_ops *targets[] = + { &xtarget_ops, &ftarget_ops, &starget_ops, 0 }; + +void parse(scanner *sc) +{ + token(sc); + + for (;;) { + if (sc->t == CTOK_EOF) + break; + if (sc->t != CTOK_WORD) + error(sc, "parse error, keyword expected"); + + /* --- Handle a forwarding request --- */ + + if (strcmp(sc->d.buf, "forward") == 0 || + strcmp(sc->d.buf, "fw") == 0 || + strcmp(sc->d.buf, "from") == 0) { + source *s; + target *t; + + token(sc); + + /* --- Read a source description --- */ + + { + source_ops **sops; + + /* --- Try to find a source type which understands --- */ + + s = 0; + for (sops = sources; *sops; sops++) { + if ((s = (*sops)->read(sc)) != 0) + goto found_source; + } + error(sc, "unknown source name `%s'", sc->d.buf); + + /* --- Read any source-specific options --- */ + + found_source: + if (sc->t == '{') { + token(sc); + while (sc->t == CTOK_WORD) { + if (!s->ops->option || !s->ops->option(s, sc)) { + error(sc, "unknown %s source option `%s'", + s->ops->name, sc->d.buf); + } + if (sc->t == ';') + token(sc); + } + if (sc->t != '}') + error(sc, "parse error, missing `}'"); + token(sc); + } + } + + /* --- Read a destination description --- */ + + if (sc->t == CTOK_WORD && (strcmp(sc->d.buf, "to") == 0 || + strcmp(sc->d.buf, "->") == 0)) + token(sc); + + { + target_ops **tops; + + /* --- Try to find a target which understands --- */ + + t = 0; + for (tops = targets; *tops; tops++) { + if ((t = (*tops)->read(sc)) != 0) + goto found_target; + } + error(sc, "unknown target name `%s'", sc->d.buf); + + /* --- Read any target-specific options --- */ + + found_target: + if (sc->t == '{') { + token(sc); + while (sc->t == CTOK_WORD) { + if (!t->ops->option || !t->ops->option(t, sc)) { + error(sc, "unknown %s target option `%s'", + t->ops->name, sc->d.buf); + } + if (sc->t == ';') + token(sc); + } + if (sc->t != '}') + error(sc, "parse error, `}' expected"); + token(sc); + } + } + + /* --- Combine the source and target --- */ + + s->ops->attach(s, sc, t); + if (t->ops->confirm) + t->ops->confirm(t); + } + + /* --- Include configuration from a file --- * + * + * Slightly tricky. Scan the optional semicolon from the including + * stream, not the included one. + */ + + else if (strcmp(sc->d.buf, "include") == 0) { + FILE *fp; + dstr d = DSTR_INIT; + + token(sc); + conf_name(sc, '/', &d); + if ((fp = fopen(d.buf, "r")) == 0) + error(sc, "can't include `%s': %s", d.buf, strerror(errno)); + if (sc->t == ';') + token(sc); + pushback(sc); + scan_push(sc, scan_file(fp, d.buf, 0)); + token(sc); + dstr_destroy(&d); + continue; /* Don't parse a trailing `;' */ + } + + /* --- Other configuration is handled elsewhere --- */ + + else { + + /* --- First try among the sources --- */ + + { + source_ops **sops; + + for (sops = sources; *sops; sops++) { + if ((*sops)->option && (*sops)->option(0, sc)) + goto found_option; + } + } + + /* --- Then try among the targets --- */ + + { + target_ops **tops; + + for (tops = targets; *tops; tops++) { + if ((*tops)->option && (*tops)->option(0, sc)) + goto found_option; + } + } + + /* --- Nobody wants the option --- */ + + error(sc, "unknown global option or prefix `%s'", sc->d.buf); + + found_option:; + } + + if (sc->t == ';') + token(sc); + } +} + +/*----- General utility functions -----------------------------------------*/ + +/* --- @fw_log@ --- * + * + * Arguments: @time_t t@ = when the connection occurred or (@-1@) + * @const char *fmt@ = format string to fill in + * @...@ = other arguments + * + * Returns: --- + * + * Use: Logs a connection. + */ + +void fw_log(time_t t, const char *fmt, ...) +{ + struct tm *tm; + dstr d = DSTR_INIT; + va_list ap; + + if (flags & FW_QUIET) + return; + + if (t == -1) + t = time(0); + tm = localtime(&t); + DENSURE(&d, 64); + d.len += strftime(d.buf, d.sz, "%Y-%m-%d %H:%M:%S ", tm); + va_start(ap, fmt); + dstr_vputf(&d, fmt, &ap); + va_end(ap); + if (flags & FW_SYSLOG) + syslog(LOG_NOTICE, "%s", d.buf); + else { + DPUTC(&d, '\n'); + dstr_write(&d, stderr); + } + DDESTROY(&d); +} + +/* --- @fw_inc@, @fw_dec@ --- * + * + * Arguments: --- + * + * Returns: --- + * + * Use: Increments or decrements the active thing count. `fw' won't + * quit while there are active things. + */ + +void fw_inc(void) { flags |= FW_SET; active++; } +void fw_dec(void) { if (active) active--; } + +/* --- @fw_exit@ --- * + * + * Arguments: --- + * + * Returns: --- + * + * Use: Exits when appropriate. + */ + +static void fw_exit(void) +{ + endpt_killall(); + source_killall(); +} + +/* --- @fw_tidy@ --- * + * + * Arguments: @int n@ = signal number + * @void *p@ = an uninteresting argument + * + * Returns: --- + * + * Use: Handles various signals and causes a clean tidy-up. + */ + +static void fw_tidy(int n, void *p) +{ + const char *sn = 0; + switch (n) { + case SIGTERM: sn = "SIGTERM"; break; + case SIGINT: sn = "SIGINT"; break; + default: abort(); + } + + fw_log(-1, "closing down gracefully on %s", sn); + source_killall(); +} + +/* --- @fw_die@ --- * + * + * Arguments: @int n@ = signal number + * @void *p@ = an uninteresting argument + * + * Returns: --- + * + * Use: Handles various signals and causes an abrupt shutdown. + */ + +static void fw_die(int n, void *p) +{ + const char *sn = 0; + switch (n) { + case SIGQUIT: sn = "SIGQUIT"; break; + default: abort(); + } + + fw_log(-1, "closing down abruptly on %s", sn); + source_killall(); + endpt_killall(); +} + +/* --- @fw_reload@ --- * + * + * Arguments: @int n@ = a signal number + * @void *p@ = an uninteresting argument + * + * Returns: --- + * + * Use: Handles a hangup signal by re-reading configuration files. + */ + +static void fw_reload(int n, void *p) +{ + FILE *fp; + scanner sc; + conffile *cf; + + assert(n == SIGHUP); + if (!conffiles) { + fw_log(-1, "no configuration files to reload: ignoring SIGHUP"); + return; + } + fw_log(-1, "reloading configuration files..."); + source_killall(); + scan_create(&sc); + for (cf = conffiles; cf; cf = cf->next) { + if ((fp = fopen(cf->name, "r")) == 0) + fw_log(-1, "error loading `%s': %s", cf->name, strerror(errno)); + else + scan_add(&sc, scan_file(fp, cf->name, 0)); + } + parse(&sc); + fw_log(-1, "... reload completed OK"); +} + +/*----- Startup and options parsing ---------------------------------------*/ /* --- Standard GNU help options --- */ static void version(FILE *fp) { - fprintf(fp, "%s version " VERSION "\n", QUIS); + pquis(fp, "$ version " VERSION "\n"); } static void usage(FILE *fp) { - fprintf(stderr, "Usage: %s [-db] [-f file] [config statements...]\n", - QUIS); + pquis(fp, "Usage: $ [-dql] [-f file] [config statements...]\n"); } static void help(FILE *fp) @@ -89,16 +425,24 @@ static void help(FILE *fp) version(fp); fputc('\n', fp); usage(fp); - fputs("\n\ -A fairly full-featured port-forwarder. Options available are:\n\ + pquis(fp, "\n\ +An excessively full-featured port-forwarder, which subsumes large chunks\n\ +of the functionality of inetd, netcat, and normal cat. Options available\n\ +are:\n\ +\n\ +-h, --help Display this help message.\n\ +-v, --version Display the program's version number.\n\ +-u, --usage Display a terse usage summary.\n\ \n\ --h, --help Display this help message.\n\ --v, --version Display the program's version number.\n\ --u, --usage Display a terse usage summary.\n\ +-G, --grammar Show a summary of the configuration language.\n\ +-O, --options Show a summary of the source and target options.\n\ \n\ --f, --file=FILE Read configuration from a file.\n\ --d, --dump Dump the configuration to standard output.\n\ --b, --background Fork into background after initializing.\n\ +-f, --file=FILE Read configuration from a file.\n\ +-q, --quiet Don't emit any logging information.\n\ +-d, --daemon Fork into background after initializing.\n\ +-l, --syslog Send log output to the system logger.\n\ +-s, --setuid=USER Change uid to USER after initializing sources.\n\ +-g, --setgid=GRP Change gid to GRP after initializing sources.\n\ \n\ Configuration may be supplied in one or more configuration files, or on\n\ the command line (or both). If no `-f' option is present, and no\n\ @@ -107,14 +451,112 @@ read.\n\ \n\ Configuration is free-form. Comments begin with a `#' character and\n\ continue to the end of the line. Each command line argument is considered\n\ -to be a separate line. The syntax is as follows:\n\ +to be a separate line.\n\ \n\ -config : stmt...\n\ -stmt : fwd-stmt | acl-stmt\n\ -fwd-stmt : `forward' [`port'] port [`to'] addr [`:'] port [fwd-attr] [`;']\n\ -fwd-attr : `{' acl-stmt... `}'\n\ -acl-stmt : (`allow' | `deny') [`from'] addr [`/' mask] [`;']\n\ -", fp); +The grammar is fairly complicated. For a summary, run `$ --grammar'.\n\ +For a summary of the various options, run `$ --options'.\n\ +"); +} + +/* --- Other helpful options --- */ + +static void grammar(FILE *fp) +{ + version(fp); + pquis(fp, "\n\ +Grammar summary\n\ +\n\ +Basic syntax\n\ + FILE ::= EMPTY | FILE STMT [`;']\n\ + STMT ::= OPTION-STMT | FW-STMT\n\ + FW-STMT ::= `fw' SOURCE OPTIONS [`to'|`->'] TARGET OPTIONS\n\ + OPTIONS ::= `{' OPTION-SEQ `}'\n\ + OPTION-SEQ ::= EMPTY | OPTION-STMT [`;'] OPTION-SEQ\n\ +\n\ +Option syntax\n\ + OPTION-STMT ::= Q-OPTION\n\ + Q-OPTION ::= OPTION\n\ + | PREFIX `.' Q-OPTION\n\ + | PREFIX `{' OPTION-SEQ `}'\n\ + PREFIX ::= WORD\n\ +\n\ +File source and target\n\ + SOURCE ::= FILE\n\ + TARGET ::= FILE\n\ + FILE ::= `file' [`.'] FSPEC [`,' FSPEC]\n\ + FSPEC ::= FD-SPEC | NAME-SPEC | NULL-SPEC\n\ + FD-SPEC ::= [[`:']`fd'[`:']] NUMBER|`stdin'|`stdout'\n\ + NAME-SPEC ::= [[`:']`name'[`:']] FILE-NAME\n\ + FILE-NAME ::= PATH-SEQ | [ PATH-SEQ ]\n\ + PATH-SEQ ::= PATH-ELT | PATH-SEQ PATH-ELT\n\ + PATH-ELT ::= `/' | WORD\n\ + NULL-SPEC ::= [`:']`null'[`:']\n\ +\n\ +Exec source and target\n\ + SOURCE ::= EXEC\n\ + TARGET ::= EXEC\n\ + EXEC ::= `exec' [`.'] CMD-SPEC\n\ + CMD-SPEC ::= SHELL-CMD | [PROG-NAME] `[' ARGV0 ARG-SEQ `]'\n\ + ARG-SEQ ::= WORD | ARG-SEQ WORD\n\ + SHELL-CMD ::= WORD\n\ + ARGV0 ::= WORD\n\ +\n\ +Socket source and target\n\ + SOURCE ::= SOCKET-SOURCE\n\ + TARGET ::= SOCKET-TARGET\n\ + SOCKET-SOURCE ::= [`socket'[`.']] [[`:']ADDR-TYPE[`:']] SOURCE-ADDR\n\ + SOCKET-TARGET ::= [`socket'[`.']] [[`:']ADDR-TYPE[`:']] TARGET-ADDR\n\ +\n\ + INET-SOURCE-ADDR ::= [`port'] PORT\n\ + INET-TARGET-ADDR ::= ADDRESS [`:'] PORT\n\ + ADDRESS ::= ADDR-ELT | ADDRESS ADDR-ELT\n\ + ADDR-ELT ::= `.' | WORD\n\ +\n\ + UNIX-SOURCE-ADDR ::= FILE-NAME\n\ + UNIX-TARGET-ADDR ::= FILE-NAME\n\ +"); +} + +static void options(FILE *fp) +{ + version(fp); + pquis(fp, "\n\ +Options summary\n\ +\n\ +File attributes (`fattr')\n\ + prefix.FATTR.MODE [=] MODE\n\ + prefix.FATTR.OWNER [=] USER\n\ + prefix.FATTR.GROUP [=] GROUP\n\ +\n\ +File options\n\ + file.create [=] yes|no\n\ + file.open [=] no|truncate|append\n\ + file.fattr.*\n\ +\n\ +Exec options\n\ + exec.logging [=] yes|no\n\ + exec.dir [=] FILE-NAME\n\ + exec.root [=] FILE-NAME\n\ + exec.user [=] USER\n\ + exec.group [=] GROUP\n\ + exec.rlimit.LIMIT[.hard|.soft] [=] VALUE\n\ + exec.env.clear\n\ + exec.env.unset VAR\n\ + exec.env.[set] VAR [=] VALUE\n\ +\n\ +Socket options\n\ + socket.conn [=] NUMBER|unlimited|one-shot\n\ + socket.listen [=] NUMBER\n\ + socket.logging [=] yes|no\n\ +\n\ + socket.inet.source.[allow|deny] [host] ADDR [/ ADDR]\n\ + socket.inet.source.[allow|deny] priv-port\n\ + socket.inet.source.addr [=] any|ADDR\n\ + socket.inet.dest.addr [=] any|ADDR\n\ + socket.inet.dest.priv-port [=] yes|no\n\ +\n\ + socket.unix.fattr.*\n\ +"); } /* --- @main@ --- * @@ -131,13 +573,16 @@ int main(int argc, char *argv[]) { unsigned f = 0; sel_state sst; + sig s_term, s_quit, s_int, s_hup; + scanner sc; + uid_t drop = -1; + gid_t dropg = -1; + conffile *cf, **cff = &conffiles; - enum { - f_bogus = 1, - f_file = 2, - f_dump = 4, - f_fork = 8 - }; +#define f_bogus 1u +#define f_file 2u +#define f_syslog 4u +#define f_fork 8u /* --- Initialize things --- */ @@ -145,7 +590,14 @@ int main(int argc, char *argv[]) sel = &sst; sel_init(sel); sub_init(); + sig_init(sel); bres_init(sel); + bres_exec(0); + exec_init(); + fattr_init(&fattr_global); + scan_create(&sc); + + atexit(fw_exit); /* --- Parse command line options --- */ @@ -158,18 +610,29 @@ int main(int argc, char *argv[]) { "version", 0, 0, 'v' }, { "usage", 0, 0, 'u' }, + /* --- Other help options --- */ + + { "grammar", 0, 0, 'G' }, + { "options", 0, 0, 'O' }, + /* --- Other useful arguments --- */ { "file", OPTF_ARGREQ, 0, 'f' }, - { "dump", 0, 0, 'd' }, - { "fork", 0, 0, 'b' }, - { "background", 0, 0, 'b' }, + { "fork", 0, 0, 'd' }, + { "daemon", 0, 0, 'd' }, + { "syslog", 0, 0, 'l' }, + { "log", 0, 0, 'l' }, + { "quiet", 0, 0, 'q' }, + { "setuid", OPTF_ARGREQ, 0, 's' }, + { "uid", OPTF_ARGREQ, 0, 's' }, + { "setgid", OPTF_ARGREQ, 0, 'g' }, + { "gid", OPTF_ARGREQ, 0, 'g' }, /* --- Magic terminator --- */ { 0, 0, 0, 0 } }; - int i = mdwopt(argc, argv, "hvu f:db", opts, 0, 0, 0); + int i = mdwopt(argc, argv, "+hvu GO f:dls:g:", opts, 0, 0, 0); if (i < 0) break; @@ -186,22 +649,64 @@ int main(int argc, char *argv[]) usage(stdout); exit(0); break; - case 'f': { - scan_filectx ctx; - FILE *fp; - if ((fp = fopen(optarg, "r")) == 0) - die(1, "couldn't open file `%s': %s", optarg, strerror(errno)); - scan_fileinit(&ctx, fp, optarg); - conf_parse(&ctx); - fclose(fp); + case 'G': + grammar(stdout); + exit(0); + break; + case 'O': + options(stdout); + exit(0); + break; + case 'f': + if (strcmp(optarg, "-") == 0) + scan_add(&sc, scan_file(stdin, "", SCF_NOCLOSE)); + else { + FILE *fp; + if ((fp = fopen(optarg, "r")) == 0) + die(1, "couldn't open file `%s': %s", optarg, strerror(errno)); + cf = CREATE(conffile); + cf->name = optarg; + *cff = cf; + cff = &cf->next; + scan_add(&sc, scan_file(fp, optarg, 0)); + } f |= f_file; - } break; - case 'd': - f |= f_dump; break; - case 'b': + case 'd': f |= f_fork; break; + case 'l': + f |= f_syslog; + break; + case 'q': + flags |= FW_QUIET; + break; + case 's': + if (isdigit((unsigned char )optarg[0])) { + char *q; + drop = strtol(optarg, &q, 0); + if (*q) + die(1, "bad uid `%s'", optarg); + } else { + struct passwd *pw = getpwnam(optarg); + if (!pw) + die(1, "unknown user `%s'", optarg); + drop = pw->pw_uid; + } + break; + case 'g': + if (isdigit((unsigned char )optarg[0])) { + char *q; + dropg = strtol(optarg, &q, 0); + if (*q) + die(1, "bad gid `%s'", optarg); + } else { + struct group *gr = getgrnam(optarg); + if (!gr) + die(1, "unknown group `%s'", optarg); + dropg = gr->gr_gid; + } + break; default: f |= f_bogus; break; @@ -212,38 +717,56 @@ int main(int argc, char *argv[]) usage(stderr); exit(1); } + *cff = 0; /* --- Deal with the remaining arguments --- */ - if (optind == argc) { - if (f & f_file) - /* Cool */; - else if (isatty(STDIN_FILENO)) { - moan("no configuration given and stdin is a terminal."); - moan("type `%s --help' for usage information.", QUIS); - exit(1); - } else { - scan_filectx ctx; - scan_fileinit(&ctx, stdin, ""); - conf_parse(&ctx); - } - } else { - scan_argvctx ctx; - scan_argvinit(&ctx, argv + optind); - conf_parse(&ctx); + if (optind < argc) + scan_add(&sc, scan_argv(argv + optind)); + else if (f & f_file) + /* Cool */; + else if (!isatty(STDIN_FILENO)) + scan_add(&sc, scan_file(stdin, "", SCF_NOCLOSE)); + else { + moan("no configuration given and stdin is a terminal."); + moan("type `%s --help' for usage information.", QUIS); + exit(1); } - /* --- Dump out the state --- */ + /* --- Parse the configuration now gathered --- */ + + parse(&sc); + + /* --- Set up some signal handlers --- * + * + * Don't enable @SIGINT@ if the caller already disabled it. + */ - if (f & f_dump) { - sel_file *s; - fputs("global acl:\n", stdout); - acl_dump(0, stdout); - for (s = sel->files; s; s = s->next) - listener_dump((listener *)s, stdout); - exit(0); + { + struct sigaction sa; + + sig_add(&s_term, SIGTERM, fw_tidy, 0); + sig_add(&s_quit, SIGQUIT, fw_die, 0); + sigaction(SIGINT, 0, &sa); + if (sa.sa_handler != SIG_IGN) + sig_add(&s_int, SIGINT, fw_tidy, 0); + sig_add(&s_hup, SIGHUP, fw_reload, 0); } + /* --- Drop privileges --- */ + + if (drop != (uid_t)-1) + privconn_split(sel); +#ifdef HAVE_SETGROUPS + if ((dropg != (gid_t)-1 && (setgid(dropg) || setgroups(1, &dropg))) || + (drop != (uid_t)-1 && setuid(drop))) + die(1, "couldn't drop privileges: %s", strerror(errno)); +#else + if ((dropg != (gid_t)-1 && setgid(dropg)) || + (drop != (uid_t)-1 && setuid(drop))) + die(1, "couldn't drop privileges: %s", strerror(errno)); +#endif + /* --- Fork into the background --- */ if (f & f_fork) { @@ -262,15 +785,35 @@ int main(int argc, char *argv[]) kid = fork(); if (kid != 0) _exit(0); + } + if (f & f_syslog) { flags |= FW_SYSLOG; openlog(QUIS, 0, LOG_DAEMON); } /* --- Let rip --- */ - for (;;) - sel_select(sel); + if (!(flags & FW_SET)) + moan("nothing to do!"); + signal(SIGPIPE, SIG_IGN); + + { + int selerr = 0; + while (active) { + if (!sel_select(sel)) + selerr = 0; + else if (errno != EINTR && errno != EAGAIN) { + fw_log(-1, "error from select: %s", strerror(errno)); + selerr++; + if (selerr > 8) { + fw_log(-1, "too many consecutive select errors: bailing out"); + exit(EXIT_FAILURE); + } + } + } + } + return (0); }