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 <syslog.h>
  16 #include <fcntl.h>
  17 #include <sys/socket.h>
  18 #include <netinet/in.h>
  19 #include <arpa/inet.h>
  20 #include <string.h>
  21 #include <dlfcn.h>
  22 #include <stdarg.h>
  23 #include <errno.h>
  24
  25 #include "utils.h"
  26 #include "tc_util.h"
  27 #include "m_ematch.h"
  28
  29 #define EMATCH_MAP "/etc/iproute2/ematch_map"
  30
  31 static struct ematch_util *ematch_list;
  32
  33 /* export to bison parser */
  34 int ematch_argc;
  35 char **ematch_argv;
  36 char *ematch_err;
  37 struct ematch *ematch_root;
  38
  39 static int begin_argc;
  40 static char **begin_argv;
  41
  42 static inline void map_warning(int num, char *kind)
  43 {
  44         fprintf(stderr,
  45             "Error: Unable to find ematch \"%s\" in %s\n" \
  46             "Please assign a unique ID to the ematch kind the suggested " \
  47             "entry is:\n" \
  48             "\t%d\t%s\n",
  49             kind, EMATCH_MAP, num, kind);
  50 }
  51
  52 static int lookup_map(__u16 num, char *dst, int len, const char *file)
  53 {
  54         int err = -EINVAL;
  55         char buf[512];
  56         FILE *fd = fopen(file, "r");
  57
  58         if (fd == NULL)
  59                 return -errno;
  60
  61         while (fgets(buf, sizeof(buf), fd)) {
  62                 char namebuf[512], *p = buf;
  63                 int id;
  64
  65                 while (*p == ' ' || *p == '\t')
  66                         p++;
  67                 if (*p == '#' || *p == '\n' || *p == 0)
  68                         continue;
  69
  70                 if (sscanf(p, "%d %s", &id, namebuf) != 2) {
  71                         fprintf(stderr, "ematch map %s corrupted at %s\n",
  72                             file, p);
  73                         goto out;
  74                 }
  75
  76                 if (id == num) {
  77                         if (dst)
  78                                 strncpy(dst, namebuf, len - 1);
  79                         err = 0;
  80                         goto out;
  81                 }
  82         }
  83
  84         err = -ENOENT;
  85 out:
  86         fclose(fd);
  87         return err;
  88 }
  89
  90 static int lookup_map_id(char *kind, int *dst, const char *file)
  91 {
  92         int err = -EINVAL;
  93         char buf[512];
  94         FILE *fd = fopen(file, "r");
  95
  96         if (fd == NULL)
  97                 return -errno;
  98
  99         while (fgets(buf, sizeof(buf), fd)) {
 100                 char namebuf[512], *p = buf;
 101                 int id;
 102
 103                 while (*p == ' ' || *p == '\t')
 104                         p++;
 105                 if (*p == '#' || *p == '\n' || *p == 0)
 106                         continue;
 107
 108                 if (sscanf(p, "%d %s", &id, namebuf) != 2) {
 109                         fprintf(stderr, "ematch map %s corrupted at %s\n",
 110                             file, p);
 111                         goto out;
 112                 }
 113
 114                 if (!strcasecmp(namebuf, kind)) {
 115                         if (dst)
 116                                 *dst = id;
 117                         err = 0;
 118                         goto out;
 119                 }
 120         }
 121
 122         err = -ENOENT;
 123         *dst = 0;
 124 out:
 125         fclose(fd);
 126         return err;
 127 }
 128
 129 static struct ematch_util *get_ematch_kind(char *kind)
 130 {
 131         static void *body;
 132         void *dlh;
 133         char buf[256];
 134         struct ematch_util *e;
 135
 136         for (e = ematch_list; e; e = e->next) {
 137                 if (strcmp(e->kind, kind) == 0)
 138                         return e;
 139         }
 140
 141         snprintf(buf, sizeof(buf), "em_%s.so", kind);
 142         dlh = dlopen(buf, RTLD_LAZY);
 143         if (dlh == NULL) {
 144                 dlh = body;
 145                 if (dlh == NULL) {
 146                         dlh = body = dlopen(NULL, RTLD_LAZY);
 147                         if (dlh == NULL)
 148                                 return NULL;
 149                 }
 150         }
 151
 152         snprintf(buf, sizeof(buf), "%s_ematch_util", kind);
 153         e = dlsym(dlh, buf);
 154         if (e == NULL)
 155                 return NULL;
 156
 157         e->next = ematch_list;
 158         ematch_list = e;
 159
 160         return e;
 161 }
 162
 163 static struct ematch_util *get_ematch_kind_num(__u16 kind)
 164 {
 165         char name[32];
 166
 167         if (lookup_map(kind, name, sizeof(name), EMATCH_MAP) < 0)
 168                 return NULL;
 169
 170         return get_ematch_kind(name);
 171 }
 172
 173 static int parse_tree(struct nlmsghdr *n, struct ematch *tree)
 174 {
 175         int index = 1;
 176         struct ematch *t;
 177
 178         for (t = tree; t; t = t->next) {
 179                 struct rtattr *tail = NLMSG_TAIL(n);
 180                 struct tcf_ematch_hdr hdr = { .flags = t->relation };
 181
 182                 if (t->inverted)
 183                         hdr.flags |= TCF_EM_INVERT;
 184
 185                 addattr_l(n, MAX_MSG, index++, NULL, 0);
 186
 187                 if (t->child) {
 188                         __u32 r = t->child_ref;
 189
 190                         addraw_l(n, MAX_MSG, &hdr, sizeof(hdr));
 191                         addraw_l(n, MAX_MSG, &r, sizeof(r));
 192                 } else {
 193                         int num = 0, err;
 194                         char buf[64];
 195                         struct ematch_util *e;
 196
 197                         if (t->args == NULL)
 198                                 return -1;
 199
 200                         strncpy(buf, (char *) t->args->data, sizeof(buf)-1);
 201                         e = get_ematch_kind(buf);
 202                         if (e == NULL) {
 203                                 fprintf(stderr, "Unknown ematch \"%s\"\n",
 204                                     buf);
 205                                 return -1;
 206                         }
 207
 208                         err = lookup_map_id(buf, &num, EMATCH_MAP);
 209                         if (err < 0) {
 210                                 if (err == -ENOENT)
 211                                         map_warning(e->kind_num, buf);
 212                                 return err;
 213                         }
 214
 215                         hdr.kind = num;
 216                         if (e->parse_eopt(n, &hdr, t->args->next) < 0)
 217                                 return -1;
 218                 }
 219
 220                 tail->rta_len = (void *) NLMSG_TAIL(n) - (void *) tail;
 221         }
 222
 223         return 0;
 224 }
 225
 226 static int flatten_tree(struct ematch *head, struct ematch *tree)
 227 {
 228         int i, count = 0;
 229         struct ematch *t;
 230
 231         for (;;) {
 232                 count++;
 233
 234                 if (tree->child) {
 235                         for (t = head; t->next; t = t->next);
 236                         t->next = tree->child;
 237                         count += flatten_tree(head, tree->child);
 238                 }
 239
 240                 if (tree->relation == 0)
 241                         break;
 242
 243                 tree = tree->next;
 244         }
 245
 246         for (i = 0, t = head; t; t = t->next, i++)
 247                 t->index = i;
 248
 249         for (t = head; t; t = t->next)
 250                 if (t->child)
 251                         t->child_ref = t->child->index;
 252
 253         return count;
 254 }
 255
 256 int em_parse_error(int err, struct bstr *args, struct bstr *carg,
 257                    struct ematch_util *e, char *fmt, ...)
 258 {
 259         va_list a;
 260
 261         va_start(a, fmt);
 262         vfprintf(stderr, fmt, a);
 263         va_end(a);
 264
 265         if (ematch_err)
 266                 fprintf(stderr, ": %s\n... ", ematch_err);
 267         else
 268                 fprintf(stderr, "\n... ");
 269
 270         while (ematch_argc < begin_argc) {
 271                 if (ematch_argc == (begin_argc - 1))
 272                         fprintf(stderr, ">>%s<< ", *begin_argv);
 273                 else
 274                         fprintf(stderr, "%s ", *begin_argv);
 275                 begin_argv++;
 276                 begin_argc--;
 277         }
 278
 279         fprintf(stderr, "...\n");
 280
 281         if (args) {
 282                 fprintf(stderr, "... %s(", e->kind);
 283                 while (args) {
 284                         fprintf(stderr, "%s", args == carg ? ">>" : "");
 285                         bstr_print(stderr, args, 1);
 286                         fprintf(stderr, "%s%s", args == carg ? "<<" : "",
 287                             args->next ? " " : "");
 288                         args = args->next;
 289                 }
 290                 fprintf(stderr, ")...\n");
 291
 292         }
 293
 294         if (e == NULL) {
 295                 fprintf(stderr,
 296                     "Usage: EXPR\n" \
 297                     "where: EXPR  := TERM [ { and | or } EXPR ]\n" \
 298                     "       TERM  := [ not ] { MATCH | '(' EXPR ')' }\n" \
 299                     "       MATCH := module '(' ARGS ')'\n" \
 300                     "       ARGS := ARG1 ARG2 ...\n" \
 301                     "\n" \
 302                     "Example: a(x y) and not (b(x) or c(x y z))\n");
 303         } else
 304                 e->print_usage(stderr);
 305
 306         return -err;
 307 }
 308
 309 static inline void free_ematch_err(void)
 310 {
 311         if (ematch_err) {
 312                 free(ematch_err);
 313                 ematch_err = NULL;
 314         }
 315 }
 316
 317 extern int ematch_parse(void);
 318
 319 int parse_ematch(int *argc_p, char ***argv_p, int tca_id, struct nlmsghdr *n)
 320 {
 321         begin_argc = ematch_argc = *argc_p;
 322         begin_argv = ematch_argv = *argv_p;
 323
 324         if (ematch_parse()) {
 325                 int err = em_parse_error(EINVAL, NULL, NULL, NULL,
 326                     "Parse error");
 327                 free_ematch_err();
 328                 return err;
 329         }
 330
 331         free_ematch_err();
 332
 333         /* undo look ahead by parser */
 334         ematch_argc++;
 335         ematch_argv--;
 336
 337         if (ematch_root) {
 338                 struct rtattr *tail, *tail_list;
 339
 340                 struct tcf_ematch_tree_hdr hdr = {
 341                         .nmatches = flatten_tree(ematch_root, ematch_root),
 342                         .progid = TCF_EM_PROG_TC
 343                 };
 344
 345                 tail = NLMSG_TAIL(n);
 346                 addattr_l(n, MAX_MSG, tca_id, NULL, 0);
 347                 addattr_l(n, MAX_MSG, TCA_EMATCH_TREE_HDR, &hdr, sizeof(hdr));
 348
 349                 tail_list = NLMSG_TAIL(n);
 350                 addattr_l(n, MAX_MSG, TCA_EMATCH_TREE_LIST, NULL, 0);
 351
 352                 if (parse_tree(n, ematch_root) < 0)
 353                         return -1;
 354
 355                 tail_list->rta_len = (void *) NLMSG_TAIL(n) - (void *) tail_list;
 356                 tail->rta_len = (void *) NLMSG_TAIL(n) - (void *) tail;
 357         }
 358
 359         *argc_p = ematch_argc;
 360         *argv_p = ematch_argv;
 361
 362         return 0;
 363 }
 364
 365 static int print_ematch_seq(FILE *fd, struct rtattr **tb, int start,
 366                             int prefix)
 367 {
 368         int n, i = start;
 369         struct tcf_ematch_hdr *hdr;
 370         int dlen;
 371         void *data;
 372
 373         for (;;) {
 374                 if (tb[i] == NULL)
 375                         return -1;
 376
 377                 dlen = RTA_PAYLOAD(tb[i]) - sizeof(*hdr);
 378                 data = (void *) RTA_DATA(tb[i]) + sizeof(*hdr);
 379
 380                 if (dlen < 0)
 381                         return -1;
 382
 383                 hdr = RTA_DATA(tb[i]);
 384
 385                 if (hdr->flags & TCF_EM_INVERT)
 386                         fprintf(fd, "NOT ");
 387
 388                 if (hdr->kind == 0) {
 389                         __u32 ref;
 390
 391                         if (dlen < sizeof(__u32))
 392                                 return -1;
 393
 394                         ref = *(__u32 *) data;
 395                         fprintf(fd, "(\n");
 396                         for (n = 0; n <= prefix; n++)
 397                                 fprintf(fd, "  ");
 398                         if (print_ematch_seq(fd, tb, ref + 1, prefix + 1) < 0)
 399                                 return -1;
 400                         for (n = 0; n < prefix; n++)
 401                                 fprintf(fd, "  ");
 402                         fprintf(fd, ") ");
 403
 404                 } else {
 405                         struct ematch_util *e;
 406
 407                         e = get_ematch_kind_num(hdr->kind);
 408                         if (e == NULL)
 409                                 fprintf(fd, "[unknown ematch %d]\n",
 410                                     hdr->kind);
 411                         else {
 412                                 fprintf(fd, "%s(", e->kind);
 413                                 if (e->print_eopt(fd, hdr, data, dlen) < 0)
 414                                         return -1;
 415                                 fprintf(fd, ")\n");
 416                         }
 417                         if (hdr->flags & TCF_EM_REL_MASK)
 418                                 for (n = 0; n < prefix; n++)
 419                                         fprintf(fd, "  ");
 420                 }
 421
 422                 switch (hdr->flags & TCF_EM_REL_MASK) {
 423                         case TCF_EM_REL_AND:
 424                                 fprintf(fd, "AND ");
 425                                 break;
 426
 427                         case TCF_EM_REL_OR:
 428                                 fprintf(fd, "OR ");
 429                                 break;
 430
 431                         default:
 432                                 return 0;
 433                 }
 434
 435                 i++;
 436         }
 437
 438         return 0;
 439 }
 440
 441 static int print_ematch_list(FILE *fd, struct tcf_ematch_tree_hdr *hdr,
 442                              struct rtattr *rta)
 443 {
 444         int err = -1;
 445         struct rtattr **tb;
 446
 447         tb = malloc((hdr->nmatches + 1) * sizeof(struct rtattr *));
 448         if (tb == NULL)
 449                 return -1;
 450
 451         if (hdr->nmatches > 0) {
 452                 if (parse_rtattr_nested(tb, hdr->nmatches, rta) < 0)
 453                         goto errout;
 454
 455                 fprintf(fd, "\n  ");
 456                 if (print_ematch_seq(fd, tb, 1, 1) < 0)
 457                         goto errout;
 458         }
 459
 460         err = 0;
 461 errout:
 462         free(tb);
 463         return err;
 464 }
 465
 466 int print_ematch(FILE *fd, const struct rtattr *rta)
 467 {
 468         struct rtattr *tb[TCA_EMATCH_TREE_MAX+1];
 469         struct tcf_ematch_tree_hdr *hdr;
 470
 471         if (parse_rtattr_nested(tb, TCA_EMATCH_TREE_MAX, rta) < 0)
 472                 return -1;
 473
 474         if (tb[TCA_EMATCH_TREE_HDR] == NULL) {
 475                 fprintf(stderr, "Missing ematch tree header\n");
 476                 return -1;
 477         }
 478
 479         if (tb[TCA_EMATCH_TREE_LIST] == NULL) {
 480                 fprintf(stderr, "Missing ematch tree list\n");
 481                 return -1;
 482         }
 483
 484         if (RTA_PAYLOAD(tb[TCA_EMATCH_TREE_HDR]) < sizeof(*hdr)) {
 485                 fprintf(stderr, "Ematch tree header size mismatch\n");
 486                 return -1;
 487         }
 488
 489         hdr = RTA_DATA(tb[TCA_EMATCH_TREE_HDR]);
 490
 491         return print_ematch_list(fd, hdr, tb[TCA_EMATCH_TREE_LIST]);
 492 }
 493
 494 struct bstr *bstr_alloc(const char *text)
 495 {
 496         struct bstr *b = calloc(1, sizeof(*b));
 497
 498         if (b == NULL)
 499                 return NULL;
 500
 501         b->data = strdup(text);
 502         if (b->data == NULL) {
 503                 free(b);
 504                 return NULL;
 505         }
 506
 507         b->len = strlen(text);
 508
 509         return b;
 510 }
 511
 512 unsigned long bstrtoul(const struct bstr *b)
 513 {
 514         char *inv = NULL;
 515         unsigned long l;
 516         char buf[b->len+1];
 517
 518         memcpy(buf, b->data, b->len);
 519         buf[b->len] = '\0';
 520
 521         l = strtoul(buf, &inv, 0);
 522         if (l == ULONG_MAX || inv == buf)
 523                 return ULONG_MAX;
 524
 525         return l;
 526 }
 527
 528 void bstr_print(FILE *fd, const struct bstr *b, int ascii)
 529 {
 530         int i;
 531         char *s = b->data;
 532
 533         if (ascii)
 534                 for (i = 0; i < b->len; i++)
 535                     fprintf(fd, "%c", isprint(s[i]) ? s[i] : '.');
 536         else {
 537                 for (i = 0; i < b->len; i++)
 538                     fprintf(fd, "%02x", s[i]);
 539                 fprintf(fd, "\"");
 540                 for (i = 0; i < b->len; i++)
 541                     fprintf(fd, "%c", isprint(s[i]) ? s[i] : '.');
 542                 fprintf(fd, "\"");
 543         }
 544 }
 545
 546 void print_ematch_tree(const struct ematch *tree)
 547 {
 548         const struct ematch *t;
 549
 550         for (t = tree; t; t = t->next) {
 551                 if (t->inverted)
 552                         printf("NOT ");
 553
 554                 if (t->child) {
 555                         printf("(");
 556                         print_ematch_tree(t->child);
 557                         printf(")");
 558                 } else {
 559                         struct bstr *b;
 560
 561                         for (b = t->args; b; b = b->next)
 562                                 printf("%s%s", b->data, b->next ? " " : "");
 563                 }
 564
 565                 if (t->relation == TCF_EM_REL_AND)
 566                         printf(" AND ");
 567                 else if (t->relation == TCF_EM_REL_OR)
 568                         printf(" OR ");
 569         }
 570 }