X-Git-Url: https://git.distorted.org.uk/~mdw/fwd/blobdiff_plain/61e3dbdf67c571ec4973ab19475ced6a438ab8df..00e3c0f1bbe99682debd4e34d3d3bd950f8c30cb:/fw.c diff --git a/fw.c b/fw.c index 202c3e7..b0eed70 100644 --- a/fw.c +++ b/fw.c @@ -1,6 +1,6 @@ /* -*-c-*- * - * $Id: fw.c,v 1.3 1999/07/26 23:30:42 mdw Exp $ + * $Id: fw.c,v 1.14 2003/01/24 20:12:40 mdw Exp $ * * Port forwarding thingy * @@ -29,6 +29,42 @@ /*----- Revision history --------------------------------------------------* * * $Log: fw.c,v $ + * Revision 1.14 2003/01/24 20:12:40 mdw + * Correctly cast uid and gid sentinel values. + * + * Revision 1.13 2002/02/22 23:45:20 mdw + * Add option to change the listen(2) parameter. Receive `fw'-specific + * code from `conf.c'. + * + * Revision 1.12 2002/01/13 14:49:17 mdw + * Track @dstr_vputf@ change. + * + * Revision 1.11 2001/02/03 20:33:26 mdw + * Fix flags to be unsigned. + * + * Revision 1.10 2001/02/03 20:30:03 mdw + * Support re-reading config files on SIGHUP. + * + * Revision 1.9 2001/01/20 11:55:17 mdw + * Handle select errors more robustly. + * + * Revision 1.8 2000/03/23 23:19:19 mdw + * Fix changed options in parser table. + * + * Revision 1.7 2000/03/23 00:37:33 mdw + * Add option to change user and group after initialization. Naughtily + * reassign short equivalents of --grammar and --options. + * + * Revision 1.6 1999/12/22 15:44:10 mdw + * Make syslog a separate option, and do it better. + * + * Revision 1.5 1999/10/22 22:47:50 mdw + * Grammar changes. Also, don't enable SIGINT if it's currently ignored. + * + * Revision 1.4 1999/10/10 16:46:12 mdw + * New resolver to initialize. Also, include options for grammar and + * options references. + * * Revision 1.3 1999/07/26 23:30:42 mdw * Major reconstruction work for new design. * @@ -45,6 +81,7 @@ #include "config.h" +#include #include #include #include @@ -57,6 +94,10 @@ #include #include +#include +#include + +#include #include #include #include @@ -65,13 +106,14 @@ #include #include -#include "bres.h" #include "conf.h" #include "endpt.h" #include "exec.h" #include "fattr.h" +#include "file.h" #include "fw.h" #include "scan.h" +#include "socket.h" #include "source.h" /*----- Global variables --------------------------------------------------*/ @@ -80,14 +122,192 @@ sel_state *sel; /* Multiplexor for nonblocking I/O */ /*----- 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 -/*----- Main code ---------------------------------------------------------*/ +/*----- 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); + } + + /* --- 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@ --- * * @@ -113,10 +333,9 @@ void fw_log(time_t t, const char *fmt, ...) t = time(0); tm = localtime(&t); DENSURE(&d, 64); - d.len += strftime(d.buf, d.sz, "%Y-%m-%d %H:%M:%S", tm); - DPUTC(&d, ' '); + d.len += strftime(d.buf, d.sz, "%Y-%m-%d %H:%M:%S ", tm); va_start(ap, fmt); - dstr_vputf(&d, fmt, ap); + dstr_vputf(&d, fmt, &ap); va_end(ap); if (flags & FW_SYSLOG) syslog(LOG_NOTICE, "%s", d.buf); @@ -167,27 +386,86 @@ static void fw_exit(void) static void fw_tidy(int n, void *p) { - const char *sn = "unexpected signal (bug!)"; - if (n == SIGTERM) - sn = "SIGTERM"; - else if (n == SIGINT) - sn = "SIGINT"; - - fw_log(-1, "closing down on %s", sn); - fw_exit(); + 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) @@ -195,17 +473,24 @@ static void help(FILE *fp) version(fp); fputc('\n', fp); usage(fp); - fputs("\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\ +-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\ +-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, --daemon 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\ @@ -216,8 +501,106 @@ 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.\n\ \n\ -The syntax is too complicated to describe here. Read the manual.\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 ::= [[`:']`file'[`:']] 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.[allow|deny] [from] address [/ address]\n\ +\n\ + socket.unix.fattr.*\n\ +"); } /* --- @main@ --- * @@ -234,14 +617,16 @@ int main(int argc, char *argv[]) { unsigned f = 0; sel_state sst; - sig s_term, s_int; + 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_fork = 8 - }; +#define f_bogus 1u +#define f_file 2u +#define f_syslog 4u +#define f_fork 8u /* --- Initialize things --- */ @@ -251,14 +636,11 @@ int main(int argc, char *argv[]) sub_init(); sig_init(sel); bres_init(sel); + bres_exec(0); exec_init(); fattr_init(&fattr_global); scan_create(&sc); - /* --- Set up some signal handlers --- */ - - sig_add(&s_term, SIGTERM, fw_tidy, 0); - sig_add(&s_int, SIGINT, fw_tidy, 0); atexit(fw_exit); /* --- Parse command line options --- */ @@ -272,18 +654,29 @@ 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' }, { "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:d", opts, 0, 0, 0); + int i = mdwopt(argc, argv, "+hvu GO f:dls:g:", opts, 0, 0, 0); if (i < 0) break; @@ -300,6 +693,14 @@ int main(int argc, char *argv[]) usage(stdout); exit(0); break; + 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)); @@ -307,6 +708,10 @@ int main(int argc, char *argv[]) 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; @@ -314,9 +719,38 @@ int main(int argc, char *argv[]) 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; @@ -327,6 +761,7 @@ int main(int argc, char *argv[]) usage(stderr); exit(1); } + *cff = 0; /* --- Deal with the remaining arguments --- */ @@ -344,7 +779,35 @@ int main(int argc, char *argv[]) /* --- Parse the configuration now gathered --- */ - conf_parse(&sc); + parse(&sc); + + /* --- Set up some signal handlers --- * + * + * Don't enable @SIGINT@ if the caller already disabled it. + */ + + { + 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 --- */ + +#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 --- */ @@ -364,7 +827,9 @@ 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); } @@ -374,8 +839,23 @@ int main(int argc, char *argv[]) if (!(flags & FW_SET)) moan("nothing to do!"); signal(SIGPIPE, SIG_IGN); - while (active) - sel_select(sel); + + { + 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); }