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.
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.
48 static const unsigned long gidmaxval= (unsigned long)((gid_t)-2);
49 static const char *const protos_ok[]= { "slip", "cslip", "adaptive", 0 };
51 static const char *configstr, *proto;
52 static unsigned long localaddr, peeraddr, mtu;
53 static int localallow, peerallow, allallow;
55 static struct exroute {
56 unsigned long prefix, mask;
58 char prefixtxt[ATXTLEN], masktxt[ATXTLEN];
59 } exroutes[MAXEXROUTES];
61 static char localtxt[ATXTLEN];
62 static char peertxt[ATXTLEN];
64 static struct pplace {
65 struct pplace *parent;
70 static void fatal(const char *fmt, ...)
71 __attribute__((format(printf,1,2)));
72 static void fatal(const char *fmt, ...) {
76 fputs("userv-ipif service: fatal error: ",stderr);
77 vfprintf(stderr, fmt, al);
82 static void sysfatal(const char *fmt, ...)
83 __attribute__((format(printf,1,2)));
84 static void sysfatal(const char *fmt, ...) {
91 fputs("userv-ipif service: fatal system error",stderr);
92 vfprintf(stderr, fmt, al);
93 fprintf(stderr,"%s\n", strerror(e));
98 static void badusage(const char *fmt, ...)
99 __attribute__((format(printf,1,2)));
100 static void badusage(const char *fmt, ...) {
106 "userv-ipif service: %s:%d: ",
107 cpplace->filename, cpplace->lineno);
109 fputs("userv-ipif service: invalid usage: ",stderr);
112 vfprintf(stderr, fmt, al);
116 for (cpp=cpplace->parent; cpp; cpp=cpp->parent) {
118 "userv-ipif service: %s:%d: ... in file included from here\n",
119 cpp->filename, cpp->lineno);
125 static char *ip2txt(unsigned long addr, char *buf) {
126 sprintf(buf, "%lu.%lu.%lu.%lu",
134 static unsigned long eat_number(const char **argp, const char *what,
135 unsigned long min, unsigned long max,
136 const char *endchars, int *endchar_r) {
137 /* If !endchars then the endchar must be a nul, otherwise it may be
138 * a nul (resulting in *argp set to 0) or something else (*argp set
139 * to point to after delim, *endchar_r set to delim).
140 * *endchar_r may be 0.
146 if (!*argp) { badusage("missing number %s\n",what); }
147 rv= strtoul(*argp,&ep,0);
148 if ((endchar= *ep)) {
149 if (!endchars) badusage("junk after number %s\n",what);
150 if (!strchr(endchars,endchar))
151 badusage("invalid character or delimiter `%c' in or after number, %s:"
152 " expected %s (or none?)\n", endchar,what,endchars);
157 if (endchar_r) *endchar_r= endchar;
158 if (rv < min || rv > max) badusage("number %s value %lu out of range %lu..%lu",
163 static void addrnet_mustdiffer(const char *w1, unsigned long p1, unsigned long m1,
164 const char *w2, unsigned long p2, unsigned long m2) {
168 if ((p1 & mask) != (p2 & mask)) return;
169 badusage("%s %08lx/%08lx overlaps/clashes with %s %08lx/%08lx",
173 static unsigned long eat_addr(const char **argp, const char *what,
174 const char *endchars, int *endchar_r) {
183 sprintf(whatbuf,"%s byte #%d",what,i);
184 rv |= eat_number(argp,whatbuf, 0,255, i<3 ? "." : endchars, endchar_r);
190 static void eat_prefixmask(const char **argp, const char *what,
191 const char *endchars, int *endchar_r,
192 unsigned long *prefix_r, unsigned long *mask_r, int *len_r) {
193 /* mask_r and len_r may be 0 */
196 unsigned long prefix, mask;
198 prefix= eat_addr(argp,what, "/",0);
199 sprintf(whatbuf,"%s length",what);
200 len= eat_number(argp,whatbuf, 0,32, endchars,endchar_r);
202 mask= (~0UL << (32-len));
203 if (prefix & ~mask) badusage("%s prefix %08lx not fully contained in mask %08lx\n",
206 if (mask_r) *mask_r= mask;
207 if (len_r) *len_r= len;
210 static int addrnet_isin(unsigned long prefix, unsigned long mask,
211 unsigned long mprefix, unsigned long mmask) {
212 return !(~mask & mmask) && (prefix & mmask) == mprefix;
216 static void permit(unsigned long pprefix, unsigned long pmask) {
219 assert(!(pprefix & ~pmask));
221 if (!proto) fputs("permits",stdout);
222 if (addrnet_isin(localaddr,~0UL, pprefix,pmask)) {
223 if (!proto) fputs(" local-addr",stdout);
226 if (addrnet_isin(peeraddr,~0UL, pprefix,pmask)) {
227 if (!proto) fputs(" peer-addr",stdout);
230 for (i=0; i<nexroutes; i++) {
231 if (addrnet_isin(exroutes[i].prefix,exroutes[i].mask, pprefix,pmask)) {
232 if (!proto) printf(" route#%d",i);
233 any= exroutes[i].allow= 1;
237 if (!any) fputs(" nothing!",stderr);
242 static void pconfig(const char *configstr, int truncated);
244 static void pfile(const char *filename) {
248 struct pplace npp, *cpp;
250 for (cpp=cpplace; cpp; cpp=cpp->parent) {
251 if (!strcmp(cpp->filename,filename))
252 badusage("recursive configuration file `%s'",filename);
255 file= fopen(filename,"r");
257 badusage("cannot open configuration file `%s': %s", filename, strerror(errno));
259 if (!proto) printf("config file `%s':\n",filename);
262 npp.filename= filename;
266 while (fgets(buf, sizeof(buf), file)) {
271 truncated= (buf[l-1] != '\n');
272 while (l>0 && isspace((unsigned char) buf[l-1])) l--;
277 while ((c= getc(file)) != EOF && c != '\n');
281 pconfig(buf,truncated);
284 badusage("failed while reading configuration file: %s", strerror(errno));
289 static void pconfig(const char *configstr, int truncated) {
290 unsigned long fgid, tgid, pprefix, pmask;
295 switch (configstr[0]) {
297 if (strcmp(configstr,"*")) badusage("`*' directive must be only thing on line");
305 if (truncated) badusage("filename too long (`%.100s...')",configstr);
310 if (!isdigit((unsigned char)configstr[0]))
311 badusage("unknown configuration directive");
313 fgid= eat_number(&configstr,"gid", 0,gidmaxval, ",",0);
314 eat_prefixmask(&configstr,"permitted-prefix", ",",0, &pprefix,&pmask,&plen);
315 if (!configstr && truncated) badusage("gid,prefix/len,... spec too long");
317 if (!proto) printf(" %5lu,%s/%d: ", fgid, ip2txt(pprefix,ptxt), plen);
319 gidlist= getenv("USERV_GID");
320 if (!gidlist) fatal("USERV_GID not set");
323 if (!proto) printf("no matching gid\n");
326 tgid= eat_number(&gidlist,"userv-gid", 0,gidmaxval, " ",0);
327 if (tgid == fgid) break;
329 permit(pprefix,pmask);
334 static void checkallow(int allow, const char *what,
335 const char *prefixtxt, const char *masktxt) {
337 fprintf(stderr,"userv-ipif service: access denied for %s, %s/%s\n",
338 what, prefixtxt, masktxt);
342 static void parseargs(int argc, const char *const *argv) {
343 unsigned long routeaddr, routemask;
345 const char *const *cprotop;
347 char erwhatbuf[100], erwhatbuf2[100];
349 if (argc < NARGS+1) { badusage("too few arguments"); }
350 if (argc > NARGS+1) { badusage("too many arguments"); }
355 if (strcmp(carg,"--")) badusage("separator argument `--' not found, got `%s'",carg);
358 localaddr= eat_addr(&carg,"local-addr", ",",0);
359 peeraddr= eat_addr(&carg,"peer-addr", ",",0);
360 mtu= eat_number(&carg,"mtu", 576,65536, ",",0);
361 localallow= peerallow= 0;
363 if (!strcmp(carg,"debug")) {
366 for (cprotop= protos_ok;
367 (proto= *cprotop) && strcmp(proto,carg);
369 if (!proto) fatal("invalid protocol");
372 addrnet_mustdiffer("local-addr",localaddr,~0UL, "peer-addr",peeraddr,~0UL);
378 if (nexroutes == MAXEXROUTES)
379 fatal("too many extra routes (only %d allowed)",MAXEXROUTES);
380 sprintf(erwhatbuf,"route#%d",nexroutes);
382 eat_prefixmask(&carg,erwhatbuf, ",",0, &routeaddr,&routemask,0);
383 if (routemask == ~0UL) {
384 addrnet_mustdiffer(erwhatbuf,routeaddr,routemask, "local-addr",localaddr,~0UL);
385 addrnet_mustdiffer(erwhatbuf,routeaddr,routemask, "peer-addr",peeraddr,~0UL);
387 for (i=0; i<nexroutes; i++) {
388 sprintf(erwhatbuf2,"route#%d",i);
389 addrnet_mustdiffer(erwhatbuf,routeaddr,routemask,
390 erwhatbuf2,exroutes[i].prefix,exroutes[i].mask);
392 exroutes[nexroutes].prefix= routeaddr;
393 exroutes[nexroutes].mask= routemask;
394 exroutes[nexroutes].allow= 0;
395 ip2txt(routeaddr,exroutes[nexroutes].prefixtxt);
396 ip2txt(routemask,exroutes[nexroutes].masktxt);
398 ip2txt(localaddr,localtxt);
399 ip2txt(peeraddr,peertxt);
402 static void checkpermit(void) {
407 checkallow(localallow,"local-addr", localtxt,"32");
408 checkallow(peerallow,"peer-addr", peertxt,"32");
409 for (i=0; i<nexroutes; i++) {
410 sprintf(erwhatbuf, "route#%d", i);
411 checkallow(exroutes[i].allow, erwhatbuf, exroutes[i].prefixtxt, exroutes[i].masktxt);
413 if (!allallow) fatal("access denied");
416 static void dumpdebug(void) __attribute__((noreturn));
417 static void dumpdebug(void) {
421 printf("protocol: debug\n"
422 "local: %08lx == %s\n"
423 "peer: %08lx == %s\n"
430 for (i=0; i<nexroutes; i++) {
431 sprintf(erwhatbuf, "route#%d:", i);
432 printf("%-9s %08lx/%08lx == %s/%s\n",
434 exroutes[i].prefix, exroutes[i].mask,
435 exroutes[i].prefixtxt, exroutes[i].masktxt);
437 if (ferror(stdout) || fclose(stdout)) sysfatal("flush stdout");
441 int main(int argc, const char *const *argv) {
442 parseargs(argc,argv);
443 pconfig(configstr,0);
445 if (!proto) dumpdebug();