X-Git-Url: https://git.distorted.org.uk/~mdw/fwd/blobdiff_plain/fc170a33ade808c25d6a7dee7dd00aba290477c3..9df1a2f2b4e3af5e03f85aebea94e25d46231bf4:/fw.c diff --git a/fw.c b/fw.c index 68871a6..2dec3c0 100644 --- a/fw.c +++ b/fw.c @@ -1,6 +1,6 @@ /* -*-c-*- * - * $Id: fw.c,v 1.7 2000/03/23 00:37:33 mdw Exp $ + * $Id: fw.c,v 1.16 2003/11/29 20:36:07 mdw Exp $ * * Port forwarding thingy * @@ -29,6 +29,34 @@ /*----- Revision history --------------------------------------------------* * * $Log: fw.c,v $ + * Revision 1.16 2003/11/29 20:36:07 mdw + * Privileged outgoing connections. + * + * Revision 1.15 2003/11/25 14:46:50 mdw + * Update docco for new options. + * + * 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. @@ -59,6 +87,7 @@ #include "config.h" +#include #include #include #include @@ -87,8 +116,11 @@ #include "endpt.h" #include "exec.h" #include "fattr.h" +#include "file.h" #include "fw.h" +#include "privconn.h" #include "scan.h" +#include "socket.h" #include "source.h" /*----- Global variables --------------------------------------------------*/ @@ -97,14 +129,194 @@ 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@ --- * * @@ -132,7 +344,7 @@ void fw_log(time_t t, const char *fmt, ...) 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); + dstr_vputf(&d, fmt, &ap); va_end(ap); if (flags & FW_SYSLOG) syslog(LOG_NOTICE, "%s", d.buf); @@ -183,16 +395,76 @@ 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) @@ -252,53 +524,53 @@ static void grammar(FILE *fp) 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\ + 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\ + 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\ + 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\ + 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\ + 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\ + 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\ + UNIX-SOURCE-ADDR ::= FILE-NAME\n\ + UNIX-TARGET-ADDR ::= FILE-NAME\n\ "); } @@ -309,9 +581,9 @@ static void options(FILE *fp) Options summary\n\ \n\ File attributes (`fattr')\n\ - prefix.fattr.mode [=] mode\n\ - prefix.fattr.owner [=] user\n\ - prefix.fattr.group [=] group\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\ @@ -320,19 +592,26 @@ File options\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.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\ + exec.env.unset VAR\n\ + exec.env.[set] VAR [=] VALUE\n\ \n\ Socket options\n\ - socket.conn [=] number|unlimited|one-shot\n\ + socket.conn [=] NUMBER|unlimited|one-shot\n\ + socket.listen [=] NUMBER\n\ socket.logging [=] yes|no\n\ - socket.inet.[allow|deny] [from] address [/ address]\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\ "); } @@ -351,17 +630,16 @@ 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_syslog = 4, - f_fork = 8 - }; +#define f_bogus 1u +#define f_file 2u +#define f_syslog 4u +#define f_fork 8u /* --- Initialize things --- */ @@ -376,20 +654,6 @@ 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 --- */ @@ -405,8 +669,8 @@ 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 --- */ @@ -457,6 +721,10 @@ 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; @@ -506,6 +774,7 @@ int main(int argc, char *argv[]) usage(stderr); exit(1); } + *cff = 0; /* --- Deal with the remaining arguments --- */ @@ -523,17 +792,37 @@ 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 --- */ + if (drop != (uid_t)-1) + privconn_split(sel); #ifdef HAVE_SETGROUPS - if ((dropg != -1 && (setgid(dropg) || setgroups(1, &dropg))) || + 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 != -1 && setgid(dropg)) || -#endif - (drop != -1 && setuid(drop))) + 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 --- */ @@ -565,8 +854,23 @@ 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); }