2 * userv service (or standalone program)
3 * for per-user IP subranges.
5 * This is invoked as root, directly from userv.
6 * Its arguments are supposed to be, in order:
8 * Specifies address ranges and gids which own them.
9 * -- Indicates that the remaining arguments are user-supplied
10 * and therefore untrusted.
11 * <local-addr>,<peer-addr>,<mtu>,<proto>
12 * As for slattach. Supported protocols are slip, cslip, and
13 * adaptive. Alternatively, set to `debug' to print debugging
14 * info. <local-addr> is address of the interface on chiark;
15 * <peer-addr> is the address of the point-to-point peer.
16 * <prefix>/<mask>,<prefix>/<mask>,...
17 * List of additional routes to add for this interface.
18 * May be the empty argument, or `-' if this is problematic.
21 * <gid>,<prefix>/<len>[,<junk>]
22 * indicating that that gid may allocate addresses in
23 * the relevant subspace (<junk> is ignored)
26 * or /<config-file-name> or ./<config-file-name> or ../<config-file-name>
27 * which refers to a file which contains lines which
30 * which means that anything is permitted
32 * Should be run from userv with no-disconnect-hup.
35 * Copyright (C) 1999 Ian Jackson
37 * This is free software; you can redistribute it and/or modify it
38 * under the terms of the GNU General Public License as published by
39 * the Free Software Foundation; either version 2 of the License, or
40 * (at your option) any later version.
42 * This program is distributed in the hope that it will be useful, but
43 * WITHOUT ANY WARRANTY; without even the implied warranty of
44 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
45 * General Public License for more details.
47 * You should have received a copy of the GNU General Public License
48 * along with userv-utils; if not, write to the Free Software
49 * Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
65 #include <sys/types.h>
73 static const unsigned long gidmaxval= (unsigned long)((gid_t)-2);
74 static const char *const protos_ok[]= { "slip", "cslip", "adaptive", 0 };
75 static const int signals[]= { SIGHUP, SIGINT, SIGTERM, 0 };
77 static const char *configstr, *proto;
78 static unsigned long localaddr, peeraddr, mtu;
79 static int localallow, peerallow, allallow;
81 static struct exroute {
82 unsigned long prefix, mask;
84 char prefixtxt[ATXTLEN], masktxt[ATXTLEN];
85 } exroutes[MAXEXROUTES];
87 static char localtxt[ATXTLEN];
88 static char peertxt[ATXTLEN];
90 static struct pplace {
91 struct pplace *parent;
97 static int slpipe[2], ptmaster, undoslattach;
98 static const char *ifname;
99 static const char *ptyname;
104 struct { pid_t sl, cout, cin, task; } byname;
105 pid_t bynumber[NPIDS];
107 sigset_t emptyset, fullset;
110 static int cleantask(void) {
115 if (pid == (pid_t)-1)
116 perror("userv-ipif: fork for undo slattach failed - cannot clean up properly");
120 static void terminate(int estatus) {
124 for (i=0; i<NPIDS; i++)
125 if (pids.bynumber[i]) kill(pids.bynumber[i], SIGTERM);
129 execlp("slattach", "slattach", "-p", "tty", ptyname, (char*)0);
130 perror("userv-ipif: exec slattach for undo slattach failed");
133 if (ifname && cleantask()) {
134 execlp("ifconfig", "ifconfig", ifname, "down", (char*)0);
135 perror("userv-ipif: exec ifconfig for undo ifconfig failed");
141 pid= waitpid(-1,&status,0);
142 if (pid == (pid_t)-1) break;
148 static void fatal(const char *fmt, ...)
149 __attribute__((format(printf,1,2)));
150 static void fatal(const char *fmt, ...) {
154 fputs("userv-ipif service: fatal error: ",stderr);
155 vfprintf(stderr, fmt, al);
160 static void sysfatal(const char *fmt, ...)
161 __attribute__((format(printf,1,2)));
162 static void sysfatal(const char *fmt, ...) {
169 fputs("userv-ipif service: fatal system error: ",stderr);
170 vfprintf(stderr, fmt, al);
171 fprintf(stderr,": %s\n", strerror(e));
176 static void badusage(const char *fmt, ...)
177 __attribute__((format(printf,1,2)));
178 static void badusage(const char *fmt, ...) {
184 "userv-ipif service: %s:%d: ",
185 cpplace->filename, cpplace->lineno);
187 fputs("userv-ipif service: invalid usage: ",stderr);
190 vfprintf(stderr, fmt, al);
194 for (cpp=cpplace->parent; cpp; cpp=cpp->parent) {
196 "userv-ipif service: %s:%d: ... in file included from here\n",
197 cpp->filename, cpp->lineno);
203 static char *ip2txt(unsigned long addr, char *buf) {
204 sprintf(buf, "%lu.%lu.%lu.%lu",
212 static unsigned long eat_number(const char **argp, const char *what,
213 unsigned long min, unsigned long max,
214 const char *endchars, int *endchar_r) {
215 /* If !endchars then the endchar must be a nul, otherwise it may be
216 * a nul (resulting in *argp set to 0) or something else (*argp set
217 * to point to after delim, *endchar_r set to delim).
218 * *endchar_r may be 0.
224 if (!*argp) { badusage("missing number %s",what); }
225 rv= strtoul(*argp,&ep,0);
226 if ((endchar= *ep)) {
227 if (!endchars) badusage("junk after number %s",what);
228 if (!strchr(endchars,endchar))
229 badusage("invalid character or delimiter `%c' in or after number, %s:"
230 " expected %s (or none?)", endchar,what,endchars);
235 if (endchar_r) *endchar_r= endchar;
236 if (rv < min || rv > max) badusage("number %s value %lu out of range %lu..%lu",
241 static void addrnet_mustdiffer(const char *w1, unsigned long p1, unsigned long m1,
242 const char *w2, unsigned long p2, unsigned long m2) {
246 if ((p1 & mask) != (p2 & mask)) return;
247 badusage("%s %08lx/%08lx overlaps/clashes with %s %08lx/%08lx",
251 static unsigned long eat_addr(const char **argp, const char *what,
252 const char *endchars, int *endchar_r) {
261 sprintf(whatbuf,"%s byte #%d",what,i);
262 rv |= eat_number(argp,whatbuf, 0,255, i<3 ? "." : endchars, endchar_r);
268 static void eat_prefixmask(const char **argp, const char *what,
269 const char *endchars, int *endchar_r,
270 unsigned long *prefix_r, unsigned long *mask_r, int *len_r) {
271 /* mask_r and len_r may be 0 */
274 unsigned long prefix, mask;
276 prefix= eat_addr(argp,what, "/",0);
277 sprintf(whatbuf,"%s length",what);
278 len= eat_number(argp,whatbuf, 0,32, endchars,endchar_r);
280 mask= (~0UL << (32-len));
281 if (prefix & ~mask) badusage("%s prefix %08lx not fully contained in mask %08lx",
284 if (mask_r) *mask_r= mask;
285 if (len_r) *len_r= len;
288 static int addrnet_isin(unsigned long prefix, unsigned long mask,
289 unsigned long mprefix, unsigned long mmask) {
290 return !(~mask & mmask) && (prefix & mmask) == mprefix;
294 static void permit(unsigned long pprefix, unsigned long pmask) {
297 assert(!(pprefix & ~pmask));
300 if (!proto) fputs("permits",stdout);
301 if (addrnet_isin(localaddr,~0UL, pprefix,pmask)) {
302 if (!proto) fputs(" local-addr",stdout);
305 if (addrnet_isin(peeraddr,~0UL, pprefix,pmask)) {
306 if (!proto) fputs(" peer-addr",stdout);
309 for (i=0; i<nexroutes; i++) {
310 if (addrnet_isin(exroutes[i].prefix,exroutes[i].mask, pprefix,pmask)) {
311 if (!proto) printf(" route#%d",i);
312 any= exroutes[i].allow= 1;
316 if (!any) fputs(" nothing",stdout);
321 static void pconfig(const char *configstr, int truncated);
323 static void pfile(const char *filename) {
327 struct pplace npp, *cpp;
329 for (cpp=cpplace; cpp; cpp=cpp->parent) {
330 if (!strcmp(cpp->filename,filename))
331 badusage("recursive configuration file `%s'",filename);
334 file= fopen(filename,"r");
336 badusage("cannot open configuration file `%s': %s", filename, strerror(errno));
338 if (!proto) printf("config file `%s':\n",filename);
341 npp.filename= filename;
345 while (fgets(buf, sizeof(buf), file)) {
350 truncated= (buf[l-1] != '\n');
351 while (l>0 && isspace((unsigned char) buf[l-1])) l--;
356 while ((c= getc(file)) != EOF && c != '\n');
360 pconfig(buf,truncated);
363 badusage("failed while reading configuration file: %s", strerror(errno));
368 static void pconfig(const char *configstr, int truncated) {
369 unsigned long fgid, tgid, pprefix, pmask;
374 switch (configstr[0]) {
376 if (strcmp(configstr,"*")) badusage("`*' directive must be only thing on line");
384 if (truncated) badusage("filename too long (`%.100s...')",configstr);
389 if (!isdigit((unsigned char)configstr[0]))
390 badusage("unknown configuration directive");
392 fgid= eat_number(&configstr,"gid", 0,gidmaxval, ",",0);
393 eat_prefixmask(&configstr,"permitted-prefix", ",",0, &pprefix,&pmask,&plen);
394 if (!configstr && truncated) badusage("gid,prefix/len,... spec too long");
396 if (!proto) printf(" %5lu,%s/%d: ", fgid, ip2txt(pprefix,ptxt), plen);
398 gidlist= getenv("USERV_GID");
399 if (!gidlist) fatal("USERV_GID not set");
402 if (!proto) printf("no matching gid\n");
405 tgid= eat_number(&gidlist,"userv-gid", 0,gidmaxval, " ",0);
406 if (tgid == fgid) break;
408 permit(pprefix,pmask);
413 static void checkallow(int allow, const char *what,
414 const char *prefixtxt, const char *masktxt) {
416 fprintf(stderr,"userv-ipif service: access denied for %s, %s/%s\n",
417 what, prefixtxt, masktxt);
421 static void parseargs(int argc, const char *const *argv) {
422 unsigned long routeaddr, routemask;
424 const char *const *cprotop;
426 char erwhatbuf[100], erwhatbuf2[100];
428 if (argc < NARGS+1) { badusage("too few arguments"); }
429 if (argc > NARGS+1) { badusage("too many arguments"); }
434 if (strcmp(carg,"--")) badusage("separator argument `--' not found, got `%s'",carg);
437 localaddr= eat_addr(&carg,"local-addr", ",",0);
438 peeraddr= eat_addr(&carg,"peer-addr", ",",0);
439 mtu= eat_number(&carg,"mtu", 576,65536, ",",0);
440 localallow= peerallow= 0;
442 if (!strcmp(carg,"debug")) {
445 for (cprotop= protos_ok;
446 (proto= *cprotop) && strcmp(proto,carg);
448 if (!proto) fatal("invalid protocol");
451 addrnet_mustdiffer("local-addr",localaddr,~0UL, "peer-addr",peeraddr,~0UL);
454 if (strcmp(carg,"-")) {
458 if (nexroutes == MAXEXROUTES)
459 fatal("too many extra routes (only %d allowed)",MAXEXROUTES);
460 sprintf(erwhatbuf,"route#%d",nexroutes);
462 eat_prefixmask(&carg,erwhatbuf, ",",0, &routeaddr,&routemask,0);
463 if (routemask == ~0UL) {
464 addrnet_mustdiffer(erwhatbuf,routeaddr,routemask, "local-addr",localaddr,~0UL);
465 addrnet_mustdiffer(erwhatbuf,routeaddr,routemask, "peer-addr",peeraddr,~0UL);
467 for (i=0; i<nexroutes; i++) {
468 sprintf(erwhatbuf2,"route#%d",i);
469 addrnet_mustdiffer(erwhatbuf,routeaddr,routemask,
470 erwhatbuf2,exroutes[i].prefix,exroutes[i].mask);
472 exroutes[nexroutes].prefix= routeaddr;
473 exroutes[nexroutes].mask= routemask;
474 exroutes[nexroutes].allow= 0;
475 ip2txt(routeaddr,exroutes[nexroutes].prefixtxt);
476 ip2txt(routemask,exroutes[nexroutes].masktxt);
480 ip2txt(localaddr,localtxt);
481 ip2txt(peeraddr,peertxt);
484 static void checkpermit(void) {
489 checkallow(localallow,"local-addr", localtxt,"32");
490 checkallow(peerallow,"peer-addr", peertxt,"32");
491 for (i=0; i<nexroutes; i++) {
492 sprintf(erwhatbuf, "route#%d", i);
493 checkallow(exroutes[i].allow, erwhatbuf, exroutes[i].prefixtxt, exroutes[i].masktxt);
495 if (!allallow) fatal("access denied");
498 static void dumpdebug(void) __attribute__((noreturn));
499 static void dumpdebug(void) {
503 printf("protocol: debug\n"
504 "local: %08lx == %s\n"
505 "peer: %08lx == %s\n"
512 for (i=0; i<nexroutes; i++) {
513 sprintf(erwhatbuf, "route#%d:", i);
514 printf("%-9s %08lx/%08lx == %s/%s\n",
516 exroutes[i].prefix, exroutes[i].mask,
517 exroutes[i].prefixtxt, exroutes[i].masktxt);
519 if (ferror(stdout) || fclose(stdout)) sysfatal("flush stdout");
524 static void setsigmask(const sigset_t *ss) {
527 r= sigprocmask(SIG_SETMASK, ss, 0);
528 if (r) sysfatal("[un]block signals");
531 static void setsignals(void (*handler)(int), struct sigaction *sa, int chldflags) {
535 sa->sa_handler= handler;
537 for (signalp=signals; (sig=*signalp); signalp++) {
538 r= sigaction(sig, sa, 0); if (r) sysfatal("uncatch signal");
540 sa->sa_flags= chldflags;
541 r= sigaction(SIGCHLD, sa, 0); if (r) sysfatal("uncatch children");
544 static void infork(void) {
547 memset(&pids,0,sizeof(pids));
548 sigemptyset(&sa.sa_mask);
549 setsignals(SIG_DFL,&sa,0);
550 setsigmask(&emptyset);
554 static pid_t makesubproc(void (*entry)(void)) {
557 pid= fork(); if (pid == (pid_t)-1) sysfatal("fork for subprocess");
565 static int task(void) {
569 if (pid == (pid_t)-1) sysfatal("fork for task");
570 if (!pid) { infork(); return 1; }
572 pids.byname.task= pid;
573 while (pids.byname.task) sigsuspend(&emptyset);
577 static void mdup2(int fd1, int fd2, const char *what) {
581 r= dup2(fd1,fd2); if (r==fd2) return;
582 if (r!=-1) fatal("dup2 in %s gave wrong answer %d instead of %d",what,r,fd2);
583 if (errno != EINTR) sysfatal("dup2 failed in %s",what);
587 static void sl_entry(void) {
588 mdup2(slpipe[1],1,"slattach child");
589 execlp("slattach", "slattach", "-v", "-L", "-p",proto, ptyname, (char*)0);
590 sysfatal("cannot exec slattach");
593 static void cin_entry(void) {
594 mdup2(ptmaster,1,"cat input child");
595 execlp("cat", "cat", (char*)0);
596 sysfatal("cannot exec cat input");
599 static void cout_entry(void) {
600 mdup2(ptmaster,0,"cat output child");
601 execlp("cat", "cat", (char*)0);
602 sysfatal("cannot exec cat output");
605 static void sighandler(int signum) {
608 const char *taskfail;
612 if (signum == SIGCHLD) {
614 pid= waitpid(-1,&status,WNOHANG);
615 if (!pid || pid == (pid_t)-1) return;
617 if (pid == pids.byname.task) {
621 } else if (pid == pids.byname.cin) {
624 taskfail= "input cat";
629 } else if (pid == pids.byname.cout) {
631 taskfail= "output cat";
632 } else if (pid == pids.byname.sl) {
634 taskfail= "slattach";
641 if (WIFEXITED(status)) {
643 "userv-ipif service: %s unexpectedly exited with exit status %d\n",
644 taskfail, WEXITSTATUS(status));
645 } else if (WIFSIGNALED(status)) {
647 "userv-ipif service: %s unexpectedly killed by signal %s%s\n",
648 taskfail, strsignal(WTERMSIG(status)),
649 WCOREDUMP(status) ? " (core dumped)" : "");
651 fprintf(stderr, "userv-ipif service: %s unexpectedly terminated"
652 " with unknown status code %d\n", taskfail, status);
657 "userv-ipif service: received signal %d, terminating\n",
664 static void startup(void) {
668 sigfillset(&fullset);
669 sigemptyset(&emptyset);
671 ptmaster= getpt(); if (ptmaster==-1) sysfatal("allocate pty master");
672 r= grantpt(ptmaster); if (r) sysfatal("grab/grant pty slave");
673 ptyname= ptsname(ptmaster); if (!ptyname) sysfatal("get pty slave name");
674 r= chmod(ptyname,0600); if (r) sysfatal("chmod pty slave");
675 r= unlockpt(ptmaster); if (r) sysfatal("unlock pty");
677 sigfillset(&sa.sa_mask);
678 setsignals(sighandler,&sa,SA_NOCLDSTOP);
679 setsigmask(&fullset);
682 static void startslattach(void) {
683 static char ifnbuf[200];
688 r= pipe(slpipe); if (r) sysfatal("create pipe");
689 piper= fdopen(slpipe[0],"r"); if (!piper) sysfatal("fdopen pipe");
692 pids.byname.sl= makesubproc(sl_entry);
695 setsigmask(&emptyset);
696 if (!fgets(ifnbuf,sizeof(ifnbuf),piper)) {
697 if (ferror(piper)) sysfatal("cannot read ifname from slattach");
698 else fatal("cannot read ifname from slattach");
700 setsigmask(&fullset);
702 if (l<=0 || ifnbuf[l-1] != '\n') fatal("slattach gave strange output `%s'",ifnbuf);
704 for (k=l; k>0 && ifnbuf[k-1]!=' '; k--);
708 static void netconfigure(void) {
713 sprintf(mtutxt,"%lu",mtu);
715 execlp("ifconfig", "ifconfig", ifname, localtxt,
716 "netmask","255.255.255.255", "-broadcast", "pointopoint",peertxt,
717 "mtu",mtutxt, "up", (char*)0);
718 sysfatal("cannot exec ifconfig");
721 for (i=0; i<nexroutes; i++) {
723 execlp("route","route", "add", "-net",exroutes[i].prefixtxt,
724 "netmask",exroutes[i].masktxt,
725 "gw",peertxt, "dev",ifname, (char*)0);
726 sysfatal("cannot exec route (for route)");
731 static void copydata(void) __attribute__((noreturn));
732 static void copydata(void) {
735 pids.byname.cin= makesubproc(cin_entry);
737 r= write(1, "\300", 1); if (r==1) break;
738 assert(r==-1); if (errno != EINTR) sysfatal("send initial delim to confirm");
740 pids.byname.cout= makesubproc(cout_entry);
742 for (;;) sigsuspend(&emptyset);
745 int main(int argc, const char *const *argv) {
746 parseargs(argc,argv);
747 pconfig(configstr,0);
749 if (!proto) dumpdebug();