mdw@git.distorted.org.uk Git - yaid/blob - policy.c

   1 /* -*-c-*-
   2  *
   3  * Policy parsing and implementation
   4  *
   5  * (c) 2012 Straylight/Edgeware
   6  */
   7
   8 /*----- Licensing notice --------------------------------------------------*
   9  *
  10  * This file is part of Yet Another Ident Daemon (YAID).
  11  *
  12  * YAID is free software; you can redistribute it and/or modify
  13  * it under the terms of the GNU General Public License as published by
  14  * the Free Software Foundation; either version 2 of the License, or
  15  * (at your option) any later version.
  16  *
  17  * YAID is distributed in the hope that it will be useful,
  18  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  19  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20  * GNU General Public License for more details.
  21  *
  22  * You should have received a copy of the GNU General Public License
  23  * along with YAID; if not, write to the Free Software Foundation,
  24  * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  25  */
  26
  27 /*----- Header files ------------------------------------------------------*/
  28
  29 #include "yaid.h"
  30
  31 /*----- Data structures ---------------------------------------------------*/
  32
  33 /*----- Static variables --------------------------------------------------*/
  34
  35 /*----- Main code ---------------------------------------------------------*/
  36
  37 /* syntax: addrpat portpat addrpar portpat policy
  38  *
  39  * local address/port first, then remote
  40  * addrpat ::= addr [/ len]
  41  * portpat ::= num | num - num | *
  42  * policy ::= user policy* | token | name | deny | hide |
  43  */
  44
  45 void init_policy(struct policy *p) { p->act.act = A_LIMIT; }
  46
  47 static void free_action(struct action *a)
  48 {
  49   switch (a->act) {
  50     case A_LIE:
  51       xfree(a->u.lie);
  52       break;
  53   }
  54   a->act = A_LIMIT;
  55 }
  56
  57 void free_policy(struct policy *p)
  58   { free_action(&p->act); }
  59
  60 static void print_addrpat(int af, const struct addrpat *ap)
  61 {
  62   char buf[ADDRLEN];
  63
  64   if (ap->len == 0) putchar('*');
  65   else printf("%s/%u", inet_ntop(af, &ap->addr, buf, sizeof(buf)), ap->len);
  66 }
  67
  68 static void print_portpat(const struct portpat *pp)
  69 {
  70   if (pp->lo == 0 && pp->hi == 65535) putchar('*');
  71   else if (pp->lo == pp->hi) printf("%u", pp->lo);
  72   else printf("%u-%u", pp->lo, pp->hi);
  73 }
  74
  75 static void print_sockpat(int af, const struct sockpat *sp)
  76   { print_addrpat(af, &sp->addr); putchar(' '); print_portpat(&sp->port); }
  77
  78 static const char *const acttab[] = {
  79 #define DEFACT(tag, name) name,
  80   ACTIONS(DEFACT)
  81 #undef DEFACT
  82   0
  83 };
  84
  85 static void print_action(const struct action *act)
  86 {
  87   assert(act->act < A_LIMIT);
  88   printf("%s", acttab[act->act]);
  89   switch (act->act) {
  90     case A_USER: {
  91       int i;
  92       unsigned m;
  93       for (i = 0, m = 1; i < A_LIMIT; i++, m <<= 1)
  94         if (act->u.user & m) printf(" %s", acttab[i]);
  95     } break;
  96     case A_LIE:
  97       printf(" %s", act->u.lie);
  98       break;
  99   }
 100 }
 101
 102 void print_policy(const struct policy *p)
 103 {
 104   print_sockpat(p->af, &p->sp[L]); putchar(' ');
 105   print_sockpat(p->af, &p->sp[R]); putchar(' ');
 106   print_action(&p->act); putchar('\n');
 107 }
 108
 109 static int match_addrpat(int af, const struct addrpat *ap,
 110                          const union addr *a)
 111 {
 112   if (!ap->len)
 113     return (1);
 114   switch (af) {
 115     case AF_INET: {
 116       unsigned mask = htonl((MASK32 << (32 - ap->len)) & MASK32);
 117       return (((ap->addr.ipv4.s_addr ^ a->ipv4.s_addr) & mask) == 0);
 118     }
 119     case AF_INET6:
 120       abort();
 121   }
 122   return (0);
 123 }
 124
 125 static int match_portpat(const struct portpat *pp, unsigned port)
 126   { return (pp->lo <= port && port <= pp->hi); }
 127
 128 static int match_sockpat(int af, const struct sockpat *sp,
 129                          const struct socket *s)
 130 {
 131   return (match_addrpat(af, &sp->addr, &s->addr) &&
 132           match_portpat(&sp->port, s->port));
 133 }
 134
 135 int match_policy(const struct policy *p, const struct query *q)
 136 {
 137   return ((!p->af || p->af == q->af) &&
 138           match_sockpat(p->af, &p->sp[L], &q->s[L]) &&
 139           match_sockpat(p->af, &p->sp[R], &q->s[R]));
 140 }
 141
 142 static void nextline(FILE *fp)
 143 {
 144   for (;;) {
 145     int ch = getc(fp);
 146     if (ch == '\n' || ch == EOF) break;
 147   }
 148 }
 149
 150 static int scan(FILE *fp, char *buf, size_t sz)
 151 {
 152   int ch;
 153
 154 skip_ws:
 155   ch = getc(fp);
 156   switch (ch) {
 157     case '\n':
 158     newline:
 159       ungetc(ch, fp);
 160       return (T_EOL);
 161     case EOF:
 162     eof:
 163       return (ferror(fp) ? T_ERROR : T_EOF);
 164     case '#':
 165       for (;;) {
 166         ch = getc(fp);
 167         if (ch == '\n') goto newline;
 168         else if (ch == EOF) goto eof;
 169       }
 170     default:
 171       if (isspace(ch)) goto skip_ws;
 172       break;
 173   }
 174
 175   for (;;) {
 176     if (sz) { *buf++ = ch; sz--; }
 177     ch = getc(fp);
 178     switch (ch) {
 179       case '\n':
 180         ungetc(ch, fp);
 181         goto done;
 182       case EOF:
 183         goto done;
 184       default:
 185         if (isspace(ch)) goto done;
 186         break;
 187     }
 188   }
 189
 190 done:
 191   if (!sz)
 192     return (T_ERROR);
 193   else {
 194     *buf++ = 0; sz--;
 195     return (T_OK);
 196   }
 197 }
 198
 199 static int parse_actname(FILE *fp, unsigned *act)
 200 {
 201   char buf[32];
 202   int t;
 203   const char *const *p;
 204
 205   if ((t = scan(fp, buf, sizeof(buf))) != 0) return (t);
 206   for (p = acttab; *p; p++)
 207     if (strcmp(buf, *p) == 0) { *act = p - acttab; return (0); }
 208   return (T_ERROR);
 209 }
 210
 211 static int parse_action(FILE *fp, struct action *act)
 212 {
 213   char buf[32];
 214   int t;
 215   unsigned a;
 216   unsigned long m;
 217
 218   if ((t = parse_actname(fp, &a)) != 0) return (t);
 219   switch (a) {
 220     case A_USER:
 221       m = 0;
 222       for (;;) {
 223         if ((t = parse_actname(fp, &a)) != 0) break;
 224         m |= (1 << a);
 225       }
 226       if (t != T_EOL && t != T_EOF) return (t);
 227       act->act = A_USER;
 228       act->u.user = m;
 229       break;
 230     case A_TOKEN:
 231     case A_NAME:
 232     case A_DENY:
 233     case A_HIDE:
 234       act->act = a;
 235       break;
 236     case A_LIE:
 237       if ((t = scan(fp, buf, sizeof(buf))) != 0) return (t);
 238       act->act = a;
 239       act->u.lie = xstrdup(buf);
 240       break;
 241   }
 242   t = scan(fp, buf, sizeof(buf));
 243   if (t != T_EOF && t != T_EOL) {
 244     free_action(act);
 245     return (T_ERROR);
 246   }
 247   return (0);
 248 }
 249
 250 static int parse_sockpat(FILE *fp, int *afp, struct sockpat *sp)
 251 {
 252   char buf[64];
 253   int t;
 254   int af;
 255   int alen;
 256   long n;
 257   char *delim;
 258
 259   if ((t = scan(fp, buf, sizeof(buf))) != 0) return (t);
 260   if (strcmp(buf, "*") == 0)
 261     sp->addr.len = 0;
 262   else {
 263     if (strchr(buf, ':')) {
 264       af = AF_INET6;
 265       alen = 128;
 266     } else {
 267       af = AF_INET;
 268       alen = 32;
 269     }
 270     if (!*afp) *afp = af;
 271     else if (*afp != af) return (T_ERROR);
 272     delim = strchr(buf, '/');
 273     if (delim) *delim++ = 0;
 274     if (!inet_pton(af, buf, &sp->addr.addr)) return (T_ERROR);
 275     if (!delim) n = alen;
 276     else n = strtol(delim, 0, 10);
 277     if (n < 0 || n > alen) return (T_ERROR);
 278     sp->addr.len = n;
 279   }
 280
 281   if ((t = scan(fp, buf, sizeof(buf))) != 0) return (T_ERROR);
 282   if (strcmp(buf, "*") == 0) {
 283     sp->port.lo = 0;
 284     sp->port.hi = 65535;
 285   } else {
 286     delim = strchr(buf, '-');
 287     if (delim) *delim++ = 0;
 288     n = strtol(buf, 0, 0);
 289     if (n < 0 || n > 65535) return (T_ERROR);
 290     sp->port.lo = n;
 291     if (!delim)
 292       sp->port.hi = n;
 293     else {
 294       n = strtol(delim, 0, 0);
 295       if (n < 0 || n > 65535) return (T_ERROR);
 296       sp->port.hi = n;
 297     }
 298   }
 299   return (0);
 300 }
 301
 302 int parse_policy(FILE *fp, struct policy *p)
 303 {
 304   int t;
 305
 306   p->af = 0;
 307   free_policy(p);
 308
 309   if ((t = parse_sockpat(fp, &p->af, &p->sp[L])) != 0) goto fail;
 310   if ((t = parse_sockpat(fp, &p->af, &p->sp[R])) != 0) goto err;
 311   if ((t = parse_action(fp, &p->act)) != 0) goto err;
 312   return (0);
 313
 314 err:
 315   t = T_ERROR;
 316 fail:
 317   free_policy(p);
 318   return (t);
 319 }
 320
 321 int open_policy_file(struct policy_file *pf, const char *name,
 322                      const char *what, const struct query *q)
 323 {
 324   if ((pf->fp = fopen(name, "r")) == 0) {
 325     logmsg(q, LOG_ERR, "failed to open %s `%s': %s",
 326            what, name, strerror(errno));
 327     return (-1);
 328   }
 329
 330   pf->name = name;
 331   pf->what = what;
 332   pf->q = q;
 333   pf->err = 0;
 334   pf->lno = 0;
 335   init_policy(&pf->p);
 336   return (0);
 337 }
 338
 339 int read_policy_file(struct policy_file *pf)
 340 {
 341   int t;
 342
 343   for (;;) {
 344     pf->lno++;
 345     t = parse_policy(pf->fp, &pf->p);
 346     switch (t) {
 347       case T_OK:
 348         nextline(pf->fp);
 349         return (0);
 350       case T_ERROR:
 351         logmsg(pf->q, LOG_ERR, "%s:%d: parse error in %s",
 352                pf->name, pf->lno, pf->what);
 353         pf->err = 1;
 354         break;
 355       case T_EOF:
 356         if (ferror(pf->fp)) {
 357           logmsg(pf->q, LOG_ERR, "failed to read %s `%s': %s",
 358                  pf->what, pf->name, strerror(errno));
 359         }
 360         return (-1);
 361       case T_EOL:
 362         nextline(pf->fp);
 363         break;
 364       default:
 365         abort();
 366     }
 367   }
 368 }
 369
 370 void close_policy_file(struct policy_file *pf)
 371 {
 372   fclose(pf->fp);
 373   free_policy(&pf->p);
 374 }
 375
 376 int load_policy_file(const char *file, policy_v *pv)
 377 {
 378   struct policy_file pf;
 379   policy_v v = DA_INIT;
 380
 381   if (open_policy_file(&pf, file, "policy file", 0))
 382     return (-1);
 383   while (!read_policy_file(&pf)) {
 384     DA_PUSH(&v, pf.p);
 385     init_policy(&pf.p);
 386   }
 387   close_policy_file(&pf);
 388   if (!pf.err) {
 389     DA_DESTROY(pv);
 390     *pv = v;
 391     return (0);
 392   } else {
 393     DA_DESTROY(&v);
 394     return (-1);
 395   }
 396 }
 397
 398 /*----- That's all, folks -------------------------------------------------*/