X-Git-Url: https://git.distorted.org.uk/~mdw/fwd/blobdiff_plain/06d823120f122fb9a9f0c291ad5b882efb17d199..a9bd543ab4ebe415bca9d6f27b90f16ddac79bc0:/fw.c diff --git a/fw.c b/fw.c index e5537fc..4b0a861 100644 --- a/fw.c +++ b/fw.c @@ -1,13 +1,11 @@ /* -*-c-*- * - * $Id: fw.c,v 1.5 1999/10/22 22:47:50 mdw Exp $ - * * Port forwarding thingy * * (c) 1999 Straylight/Edgeware */ -/*----- Licensing notice --------------------------------------------------* +/*----- Licensing notice --------------------------------------------------* * * This file is part of the `fw' port forwarder. * @@ -15,71 +13,18 @@ * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. - * + * * `fw' 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 `fw'; if not, write to the Free Software Foundation, * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ -/*----- Revision history --------------------------------------------------* - * - * $Log: fw.c,v $ - * 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. - * - * 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 "conf.h" -#include "endpt.h" -#include "exec.h" -#include "fattr.h" #include "fw.h" -#include "scan.h" -#include "source.h" /*----- Global variables --------------------------------------------------*/ @@ -87,14 +32,194 @@ 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); + 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@ --- * * @@ -120,10 +245,9 @@ 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); @@ -174,16 +298,76 @@ 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) @@ -193,7 +377,7 @@ static void version(FILE *fp) static void usage(FILE *fp) { - pquis(fp, "Usage: $ [-db] [-f file] [config statements...]\n"); + pquis(fp, "Usage: $ [-dql] [-p PIDFILE] [-f FILE] [CONFIG-STMTS...]\n"); } static void help(FILE *fp) @@ -203,18 +387,7 @@ static void help(FILE *fp) usage(fp); 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\ --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\ +of the functionality of inetd, netcat, and normal cat.\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\ @@ -227,6 +400,26 @@ to be a separate line.\n\ \n\ The grammar is fairly complicated. For a summary, run `$ --grammar'.\n\ For a summary of the various options, run `$ --options'.\n\ +\n\ +Options available are:\n\ +\n\ +Help options:\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\ +Configuration 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\ +Other options:\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\ + -p, --pidfile=FILE Write process-id to the named FILE.\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\ "); } @@ -235,93 +428,15 @@ For a summary of the various options, run `$ --options'.\n\ 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\ -"); + fputs("\nGrammar summary\n\n", fp); + fputs(grammar_text, fp); } 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.logging [=] yes|no\n\ - socket.inet.[allow|deny] [from] address [/ address]\n\ - socket.unix.fattr.*\n\ -"); + fputs("\nOption summary\n\n", fp); + fputs(option_text, fp); } /* --- @main@ --- * @@ -338,14 +453,17 @@ 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; + const char *pidfile = 0; + 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 --- */ @@ -360,20 +478,6 @@ int main(int argc, char *argv[]) fattr_init(&fattr_global); scan_create(&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); - sigaction(SIGINT, 0, &sa); - if (sa.sa_handler != SIG_IGN) - sig_add(&s_int, SIGINT, fw_tidy, 0); - } - atexit(fw_exit); /* --- Parse command line options --- */ @@ -389,21 +493,28 @@ int main(int argc, char *argv[]) /* --- Other help options --- */ - { "grammar", 0, 0, 'g' }, - { "options", 0, 0, 'o' }, + { "grammar", 0, 0, 'G' }, + { "options", 0, 0, 'O' }, /* --- Other useful arguments --- */ { "file", OPTF_ARGREQ, 0, 'f' }, { "fork", 0, 0, 'd' }, { "daemon", 0, 0, 'd' }, + { "pidfile", OPTF_ARGREQ, 0, 'p' }, + { "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 go f:d", opts, 0, 0, 0); + int i = mdwopt(argc, argv, "+hvu" "GO" "f:dp:ls:g:", opts, 0, 0, 0); if (i < 0) break; @@ -420,11 +531,11 @@ int main(int argc, char *argv[]) usage(stdout); exit(0); break; - case 'g': + case 'G': grammar(stdout); exit(0); break; - case 'o': + case 'O': options(stdout); exit(0); break; @@ -435,6 +546,10 @@ 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; @@ -442,9 +557,41 @@ int main(int argc, char *argv[]) case 'd': f |= f_fork; break; + case 'p': + pidfile = optarg; + 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; @@ -455,6 +602,7 @@ int main(int argc, char *argv[]) usage(stderr); exit(1); } + *cff = 0; /* --- Deal with the remaining arguments --- */ @@ -472,7 +620,23 @@ 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); + } /* --- Fork into the background --- */ @@ -492,18 +656,61 @@ int main(int argc, char *argv[]) kid = fork(); if (kid != 0) _exit(0); + } + if (pidfile) { + FILE *fp = fopen(pidfile, "w"); + if (!fp) { + die(EXIT_FAILURE, "couldn't create pidfile `%s': %s", + pidfile, strerror(errno)); + } + fprintf(fp, "%lu\n", (unsigned long)getpid()); + if (fflush(fp) || ferror(fp) || fclose(fp)) { + die(EXIT_FAILURE, "couldn't write pidfile `%s': %s", + pidfile, strerror(errno)); + } + } + if (f & f_syslog) { flags |= FW_SYSLOG; openlog(QUIS, 0, LOG_DAEMON); } + /* --- 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 + /* --- Let rip --- */ 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); }