tc/m_ematch.c

   1 /*
   2  * m_ematch.c           Extended Matches
   3  *
   4  *              This program is free software; you can distribute it and/or
   5  *              modify it under the terms of the GNU General Public License
   6  *              as published by the Free Software Foundation; either version
   7  *              2 of the License, or (at your option) any later version.
   8  *
   9  * Authors:     Thomas Graf <tgraf@suug.ch>
  10  */
  11
  12 #include <stdio.h>
  13 #include <stdlib.h>
  14 #include <unistd.h>
  15 #include <fcntl.h>
  16 #include <sys/socket.h>
  17 #include <netinet/in.h>
  18 #include <arpa/inet.h>
  19 #include <string.h>
  20 #include <dlfcn.h>
  21 #include <stdarg.h>
  22 #include <errno.h>
  23
  24 #include "utils.h"
  25 #include "tc_util.h"
  26 #include "m_ematch.h"
  27
  28 #define EMATCH_MAP "/etc/iproute2/ematch_map"
  29
  30 static struct ematch_util *ematch_list;
  31
  32 /* export to bison parser */
  33 int ematch_argc;
  34 char **ematch_argv;
  35 char *ematch_err;
  36 struct ematch *ematch_root;
  37
  38 static int begin_argc;
  39 static char **begin_argv;
  40
  41 static inline void map_warning(int num, char *kind)
  42 {
  43         fprintf(stderr,
  44             "Error: Unable to find ematch \"%s\" in %s\n" \
  45             "Please assign a unique ID to the ematch kind the suggested " \
  46             "entry is:\n" \
  47             "\t%d\t%s\n",
  48             kind, EMATCH_MAP, num, kind);
  49 }
  50
  51 static int lookup_map(__u16 num, char *dst, int len, const char *file)
  52 {
  53         int err = -EINVAL;
  54         char buf[512];
  55         FILE *fd = fopen(file, "r");
  56
  57         if (fd == NULL)
  58                 return -errno;
  59
  60         while (fgets(buf, sizeof(buf), fd)) {
  61                 char namebuf[512], *p = buf;
  62                 int id;
  63
  64                 while (*p == ' ' || *p == '\t')
  65                         p++;
  66                 if (*p == '#' || *p == '\n' || *p == 0)
  67                         continue;
  68
  69                 if (sscanf(p, "%d %s", &id, namebuf) != 2) {
  70                         fprintf(stderr, "ematch map %s corrupted at %s\n",
  71                             file, p);
  72                         goto out;
  73                 }
  74
  75                 if (id == num) {
  76                         if (dst)
  77                                 strncpy(dst, namebuf, len - 1);
  78                         err = 0;
  79                         goto out;
  80                 }
  81         }
  82
  83         err = -ENOENT;
  84 out:
  85         fclose(fd);
  86         return err;
  87 }
  88
  89 static int lookup_map_id(char *kind, int *dst, const char *file)
  90 {
  91         int err = -EINVAL;
  92         char buf[512];
  93         FILE *fd = fopen(file, "r");
  94
  95         if (fd == NULL)
  96                 return -errno;
  97
  98         while (fgets(buf, sizeof(buf), fd)) {
  99                 char namebuf[512], *p = buf;
 100                 int id;
 101
 102                 while (*p == ' ' || *p == '\t')
 103                         p++;
 104                 if (*p == '#' || *p == '\n' || *p == 0)
 105                         continue;
 106
 107                 if (sscanf(p, "%d %s", &id, namebuf) != 2) {
 108                         fprintf(stderr, "ematch map %s corrupted at %s\n",
 109                             file, p);
 110                         goto out;
 111                 }
 112
 113                 if (!strcasecmp(namebuf, kind)) {
 114                         if (dst)
 115                                 *dst = id;
 116                         err = 0;
 117                         goto out;
 118                 }
 119         }
 120
 121         err = -ENOENT;
 122         *dst = 0;
 123 out:
 124         fclose(fd);
 125         return err;
 126 }
 127
 128 static struct ematch_util *get_ematch_kind(char *kind)
 129 {
 130         static void *body;
 131         void *dlh;
 132         char buf[256];
 133         struct ematch_util *e;
 134
 135         for (e = ematch_list; e; e = e->next) {
 136                 if (strcmp(e->kind, kind) == 0)
 137                         return e;
 138         }
 139
 140         snprintf(buf, sizeof(buf), "em_%s.so", kind);
 141         dlh = dlopen(buf, RTLD_LAZY);
 142         if (dlh == NULL) {
 143                 dlh = body;
 144                 if (dlh == NULL) {
 145                         dlh = body = dlopen(NULL, RTLD_LAZY);
 146                         if (dlh == NULL)
 147                                 return NULL;
 148                 }
 149         }
 150
 151         snprintf(buf, sizeof(buf), "%s_ematch_util", kind);
 152         e = dlsym(dlh, buf);
 153         if (e == NULL)
 154                 return NULL;
 155
 156         e->next = ematch_list;
 157         ematch_list = e;
 158
 159         return e;
 160 }
 161
 162 static struct ematch_util *get_ematch_kind_num(__u16 kind)
 163 {
 164         char name[513];
 165
 166         if (lookup_map(kind, name, sizeof(name), EMATCH_MAP) < 0)
 167                 return NULL;
 168
 169         return get_ematch_kind(name);
 170 }
 171
 172 static int parse_tree(struct nlmsghdr *n, struct ematch *tree)
 173 {
 174         int index = 1;
 175         struct ematch *t;
 176
 177         for (t = tree; t; t = t->next) {
 178                 struct rtattr *tail = NLMSG_TAIL(n);
 179                 struct tcf_ematch_hdr hdr = { .flags = t->relation };
 180
 181                 if (t->inverted)
 182                         hdr.flags |= TCF_EM_INVERT;
 183
 184                 addattr_l(n, MAX_MSG, index++, NULL, 0);
 185
 186                 if (t->child) {
 187                         __u32 r = t->child_ref;
 188
 189                         addraw_l(n, MAX_MSG, &hdr, sizeof(hdr));
 190                         addraw_l(n, MAX_MSG, &r, sizeof(r));
 191                 } else {
 192                         int num = 0, err;
 193                         char buf[64];
 194                         struct ematch_util *e;
 195
 196                         if (t->args == NULL)
 197                                 return -1;
 198
 199                         strncpy(buf, (char *) t->args->data, sizeof(buf)-1);
 200                         e = get_ematch_kind(buf);
 201                         if (e == NULL) {
 202                                 fprintf(stderr, "Unknown ematch \"%s\"\n",
 203                                     buf);
 204                                 return -1;
 205                         }
 206
 207                         err = lookup_map_id(buf, &num, EMATCH_MAP);
 208                         if (err < 0) {
 209                                 if (err == -ENOENT)
 210                                         map_warning(e->kind_num, buf);
 211                                 return err;
 212                         }
 213
 214                         hdr.kind = num;
 215                         if (e->parse_eopt(n, &hdr, t->args->next) < 0)
 216                                 return -1;
 217                 }
 218
 219                 tail->rta_len = (void *) NLMSG_TAIL(n) - (void *) tail;
 220         }
 221
 222         return 0;
 223 }
 224
 225 static int flatten_tree(struct ematch *head, struct ematch *tree)
 226 {
 227         int i, count = 0;
 228         struct ematch *t;
 229
 230         for (;;) {
 231                 count++;
 232
 233                 if (tree->child) {
 234                         for (t = head; t->next; t = t->next);
 235                         t->next = tree->child;
 236                         count += flatten_tree(head, tree->child);
 237                 }
 238
 239                 if (tree->relation == 0)
 240                         break;
 241
 242                 tree = tree->next;
 243         }
 244
 245         for (i = 0, t = head; t; t = t->next, i++)
 246                 t->index = i;
 247
 248         for (t = head; t; t = t->next)
 249                 if (t->child)
 250                         t->child_ref = t->child->index;
 251
 252         return count;
 253 }
 254
 255 int em_parse_error(int err, struct bstr *args, struct bstr *carg,
 256                    struct ematch_util *e, char *fmt, ...)
 257 {
 258         va_list a;
 259
 260         va_start(a, fmt);
 261         vfprintf(stderr, fmt, a);
 262         va_end(a);
 263
 264         if (ematch_err)
 265                 fprintf(stderr, ": %s\n... ", ematch_err);
 266         else
 267                 fprintf(stderr, "\n... ");
 268
 269         while (ematch_argc < begin_argc) {
 270                 if (ematch_argc == (begin_argc - 1))
 271                         fprintf(stderr, ">>%s<< ", *begin_argv);
 272                 else
 273                         fprintf(stderr, "%s ", *begin_argv);
 274                 begin_argv++;
 275                 begin_argc--;
 276         }
 277
 278         fprintf(stderr, "...\n");
 279
 280         if (args) {
 281                 fprintf(stderr, "... %s(", e->kind);
 282                 while (args) {
 283                         fprintf(stderr, "%s", args == carg ? ">>" : "");
 284                         bstr_print(stderr, args, 1);
 285                         fprintf(stderr, "%s%s", args == carg ? "<<" : "",
 286                             args->next ? " " : "");
 287                         args = args->next;
 288                 }
 289                 fprintf(stderr, ")...\n");
 290
 291         }
 292
 293         if (e == NULL) {
 294                 fprintf(stderr,
 295                     "Usage: EXPR\n" \
 296                     "where: EXPR  := TERM [ { and | or } EXPR ]\n" \
 297                     "       TERM  := [ not ] { MATCH | '(' EXPR ')' }\n" \
 298                     "       MATCH := module '(' ARGS ')'\n" \
 299                     "       ARGS := ARG1 ARG2 ...\n" \
 300                     "\n" \
 301                     "Example: a(x y) and not (b(x) or c(x y z))\n");
 302         } else
 303                 e->print_usage(stderr);
 304
 305         return -err;
 306 }
 307
 308 static inline void free_ematch_err(void)
 309 {
 310         if (ematch_err) {
 311                 free(ematch_err);
 312                 ematch_err = NULL;
 313         }
 314 }
 315
 316 extern int ematch_parse(void);
 317
 318 int parse_ematch(int *argc_p, char ***argv_p, int tca_id, struct nlmsghdr *n)
 319 {
 320         begin_argc = ematch_argc = *argc_p;
 321         begin_argv = ematch_argv = *argv_p;
 322
 323         if (ematch_parse()) {
 324                 int err = em_parse_error(EINVAL, NULL, NULL, NULL,
 325                     "Parse error");
 326                 free_ematch_err();
 327                 return err;
 328         }
 329
 330         free_ematch_err();
 331
 332         /* undo look ahead by parser */
 333         ematch_argc++;
 334         ematch_argv--;
 335
 336         if (ematch_root) {
 337                 struct rtattr *tail, *tail_list;
 338
 339                 struct tcf_ematch_tree_hdr hdr = {
 340                         .nmatches = flatten_tree(ematch_root, ematch_root),
 341                         .progid = TCF_EM_PROG_TC
 342                 };
 343
 344                 tail = NLMSG_TAIL(n);
 345                 addattr_l(n, MAX_MSG, tca_id, NULL, 0);
 346                 addattr_l(n, MAX_MSG, TCA_EMATCH_TREE_HDR, &hdr, sizeof(hdr));
 347
 348                 tail_list = NLMSG_TAIL(n);
 349                 addattr_l(n, MAX_MSG, TCA_EMATCH_TREE_LIST, NULL, 0);
 350
 351                 if (parse_tree(n, ematch_root) < 0)
 352                         return -1;
 353
 354                 tail_list->rta_len = (void *) NLMSG_TAIL(n) - (void *) tail_list;
 355                 tail->rta_len = (void *) NLMSG_TAIL(n) - (void *) tail;
 356         }
 357
 358         *argc_p = ematch_argc;
 359         *argv_p = ematch_argv;
 360
 361         return 0;
 362 }
 363
 364 static int print_ematch_seq(FILE *fd, struct rtattr **tb, int start,
 365                             int prefix)
 366 {
 367         int n, i = start;
 368         struct tcf_ematch_hdr *hdr;
 369         int dlen;
 370         void *data;
 371
 372         for (;;) {
 373                 if (tb[i] == NULL)
 374                         return -1;
 375
 376                 dlen = RTA_PAYLOAD(tb[i]) - sizeof(*hdr);
 377                 data = (void *) RTA_DATA(tb[i]) + sizeof(*hdr);
 378
 379                 if (dlen < 0)
 380                         return -1;
 381
 382                 hdr = RTA_DATA(tb[i]);
 383
 384                 if (hdr->flags & TCF_EM_INVERT)
 385                         fprintf(fd, "NOT ");
 386
 387                 if (hdr->kind == 0) {
 388                         __u32 ref;
 389
 390                         if (dlen < sizeof(__u32))
 391                                 return -1;
 392
 393                         ref = *(__u32 *) data;
 394                         fprintf(fd, "(\n");
 395                         for (n = 0; n <= prefix; n++)
 396                                 fprintf(fd, "  ");
 397                         if (print_ematch_seq(fd, tb, ref + 1, prefix + 1) < 0)
 398                                 return -1;
 399                         for (n = 0; n < prefix; n++)
 400                                 fprintf(fd, "  ");
 401                         fprintf(fd, ") ");
 402
 403                 } else {
 404                         struct ematch_util *e;
 405
 406                         e = get_ematch_kind_num(hdr->kind);
 407                         if (e == NULL)
 408                                 fprintf(fd, "[unknown ematch %d]\n",
 409                                     hdr->kind);
 410                         else {
 411                                 fprintf(fd, "%s(", e->kind);
 412                                 if (e->print_eopt(fd, hdr, data, dlen) < 0)
 413                                         return -1;
 414                                 fprintf(fd, ")\n");
 415                         }
 416                         if (hdr->flags & TCF_EM_REL_MASK)
 417                                 for (n = 0; n < prefix; n++)
 418                                         fprintf(fd, "  ");
 419                 }
 420
 421                 switch (hdr->flags & TCF_EM_REL_MASK) {
 422                         case TCF_EM_REL_AND:
 423                                 fprintf(fd, "AND ");
 424                                 break;
 425
 426                         case TCF_EM_REL_OR:
 427                                 fprintf(fd, "OR ");
 428                                 break;
 429
 430                         default:
 431                                 return 0;
 432                 }
 433
 434                 i++;
 435         }
 436
 437         return 0;
 438 }
 439
 440 static int print_ematch_list(FILE *fd, struct tcf_ematch_tree_hdr *hdr,
 441                              struct rtattr *rta)
 442 {
 443         int err = -1;
 444         struct rtattr **tb;
 445
 446         tb = malloc((hdr->nmatches + 1) * sizeof(struct rtattr *));
 447         if (tb == NULL)
 448                 return -1;
 449
 450         if (hdr->nmatches > 0) {
 451                 if (parse_rtattr_nested(tb, hdr->nmatches, rta) < 0)
 452                         goto errout;
 453
 454                 fprintf(fd, "\n  ");
 455                 if (print_ematch_seq(fd, tb, 1, 1) < 0)
 456                         goto errout;
 457         }
 458
 459         err = 0;
 460 errout:
 461         free(tb);
 462         return err;
 463 }
 464
 465 int print_ematch(FILE *fd, const struct rtattr *rta)
 466 {
 467         struct rtattr *tb[TCA_EMATCH_TREE_MAX+1];
 468         struct tcf_ematch_tree_hdr *hdr;
 469
 470         if (parse_rtattr_nested(tb, TCA_EMATCH_TREE_MAX, rta) < 0)
 471                 return -1;
 472
 473         if (tb[TCA_EMATCH_TREE_HDR] == NULL) {
 474                 fprintf(stderr, "Missing ematch tree header\n");
 475                 return -1;
 476         }
 477
 478         if (tb[TCA_EMATCH_TREE_LIST] == NULL) {
 479                 fprintf(stderr, "Missing ematch tree list\n");
 480                 return -1;
 481         }
 482
 483         if (RTA_PAYLOAD(tb[TCA_EMATCH_TREE_HDR]) < sizeof(*hdr)) {
 484                 fprintf(stderr, "Ematch tree header size mismatch\n");
 485                 return -1;
 486         }
 487
 488         hdr = RTA_DATA(tb[TCA_EMATCH_TREE_HDR]);
 489
 490         return print_ematch_list(fd, hdr, tb[TCA_EMATCH_TREE_LIST]);
 491 }
 492
 493 struct bstr *bstr_alloc(const char *text)
 494 {
 495         struct bstr *b = calloc(1, sizeof(*b));
 496
 497         if (b == NULL)
 498                 return NULL;
 499
 500         b->data = strdup(text);
 501         if (b->data == NULL) {
 502                 free(b);
 503                 return NULL;
 504         }
 505
 506         b->len = strlen(text);
 507
 508         return b;
 509 }
 510
 511 unsigned long bstrtoul(const struct bstr *b)
 512 {
 513         char *inv = NULL;
 514         unsigned long l;
 515         char buf[b->len+1];
 516
 517         memcpy(buf, b->data, b->len);
 518         buf[b->len] = '\0';
 519
 520         l = strtoul(buf, &inv, 0);
 521         if (l == ULONG_MAX || inv == buf)
 522                 return ULONG_MAX;
 523
 524         return l;
 525 }
 526
 527 void bstr_print(FILE *fd, const struct bstr *b, int ascii)
 528 {
 529         int i;
 530         char *s = b->data;
 531
 532         if (ascii)
 533                 for (i = 0; i < b->len; i++)
 534                     fprintf(fd, "%c", isprint(s[i]) ? s[i] : '.');
 535         else {
 536                 for (i = 0; i < b->len; i++)
 537                     fprintf(fd, "%02x", s[i]);
 538                 fprintf(fd, "\"");
 539                 for (i = 0; i < b->len; i++)
 540                     fprintf(fd, "%c", isprint(s[i]) ? s[i] : '.');
 541                 fprintf(fd, "\"");
 542         }
 543 }
 544
 545 void print_ematch_tree(const struct ematch *tree)
 546 {
 547         const struct ematch *t;
 548
 549         for (t = tree; t; t = t->next) {
 550                 if (t->inverted)
 551                         printf("NOT ");
 552
 553                 if (t->child) {
 554                         printf("(");
 555                         print_ematch_tree(t->child);
 556                         printf(")");
 557                 } else {
 558                         struct bstr *b;
 559
 560                         for (b = t->args; b; b = b->next)
 561                                 printf("%s%s", b->data, b->next ? " " : "");
 562                 }
 563
 564                 if (t->relation == TCF_EM_REL_AND)
 565                         printf(" AND ");
 566                 else if (t->relation == TCF_EM_REL_OR)
 567                         printf(" OR ");
 568         }
 569 }