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 = NULL;
  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         return NULL;
 173 }
 174
 175 static int parse_tree(struct nlmsghdr *n, struct ematch *tree)
 176 {
 177         int index = 1;
 178         struct ematch *t;
 179
 180         for (t = tree; t; t = t->next) {
 181                 struct rtattr *tail = NLMSG_TAIL(n);
 182                 struct tcf_ematch_hdr hdr = {
 183                         .flags = t->relation
 184                 };
 185
 186                 if (t->inverted)
 187                         hdr.flags |= TCF_EM_INVERT;
 188
 189                 addattr_l(n, MAX_MSG, index++, NULL, 0);
 190
 191                 if (t->child) {
 192                         __u32 r = t->child_ref;
 193                         addraw_l(n, MAX_MSG, &hdr, sizeof(hdr));
 194                         addraw_l(n, MAX_MSG, &r, sizeof(r));
 195                 } else {
 196                         int num = 0, err;
 197                         char buf[64];
 198                         struct ematch_util *e;
 199
 200                         if (t->args == NULL)
 201                                 return -1;
 202
 203                         strncpy(buf, (char*) t->args->data, sizeof(buf)-1);
 204                         e = get_ematch_kind(buf);
 205                         if (e == NULL) {
 206                                 fprintf(stderr, "Unknown ematch \"%s\"\n",
 207                                     buf);
 208                                 return -1;
 209                         }
 210
 211                         err = lookup_map_id(buf, &num, EMATCH_MAP);
 212                         if (err < 0) {
 213                                 if (err == -ENOENT)
 214                                         map_warning(e->kind_num, buf);
 215                                 return err;
 216                         }
 217
 218                         hdr.kind = num;
 219                         if (e->parse_eopt(n, &hdr, t->args->next) < 0)
 220                                 return -1;
 221                 }
 222
 223                 tail->rta_len = (void*) NLMSG_TAIL(n) - (void*) tail;
 224         }
 225
 226         return 0;
 227 }
 228
 229 static int flatten_tree(struct ematch *head, struct ematch *tree)
 230 {
 231         int i, count = 0;
 232         struct ematch *t;
 233
 234         for (;;) {
 235                 count++;
 236
 237                 if (tree->child) {
 238                         for (t = head; t->next; t = t->next);
 239                         t->next = tree->child;
 240                         count += flatten_tree(head, tree->child);
 241                 }
 242
 243                 if (tree->relation == 0)
 244                         break;
 245
 246                 tree = tree->next;
 247         }
 248
 249         for (i = 0, t = head; t; t = t->next, i++)
 250                 t->index = i;
 251
 252         for (t = head; t; t = t->next)
 253                 if (t->child)
 254                         t->child_ref = t->child->index;
 255
 256         return count;
 257 }
 258
 259 int em_parse_error(int err, struct bstr *args, struct bstr *carg,
 260                    struct ematch_util *e, char *fmt, ...)
 261 {
 262         va_list a;
 263
 264         va_start(a, fmt);
 265         vfprintf(stderr, fmt, a);
 266         va_end(a);
 267
 268         if (ematch_err)
 269                 fprintf(stderr, ": %s\n... ", ematch_err);
 270         else
 271                 fprintf(stderr, "\n... ");
 272
 273         while (ematch_argc < begin_argc) {
 274                 if (ematch_argc == (begin_argc - 1))
 275                         fprintf(stderr, ">>%s<< ", *begin_argv);
 276                 else
 277                         fprintf(stderr, "%s ", *begin_argv);
 278                 begin_argv++;
 279                 begin_argc--;
 280         }
 281
 282         fprintf(stderr, "...\n");
 283
 284         if (args) {
 285                 fprintf(stderr, "... %s(", e->kind);
 286                 while (args) {
 287                         fprintf(stderr, "%s", args == carg ? ">>" : "");
 288                         bstr_print(stderr, args, 1);
 289                         fprintf(stderr, "%s%s", args == carg ? "<<" : "",
 290                             args->next ? " " : "");
 291                         args = args->next;
 292                 }
 293                 fprintf(stderr, ")...\n");
 294
 295         }
 296
 297         if (e == NULL) {
 298                 fprintf(stderr,
 299                     "Usage: EXPR\n" \
 300                     "where: EXPR  := TERM [ { and | or } EXPR ]\n" \
 301                     "       TERM  := [ not ] { MATCH | '(' EXPR ')' }\n" \
 302                     "       MATCH := module '(' ARGS ')'\n" \
 303                     "       ARGS := ARG1 ARG2 ...\n" \
 304                     "\n" \
 305                     "Example: a(x y) and not (b(x) or c(x y z))\n");
 306         } else
 307                 e->print_usage(stderr);
 308
 309         return -err;
 310 }
 311
 312 static inline void free_ematch_err(void)
 313 {
 314         if (ematch_err) {
 315                 free(ematch_err);
 316                 ematch_err = NULL;
 317         }
 318 }
 319
 320 extern int ematch_parse(void);
 321
 322 int parse_ematch(int *argc_p, char ***argv_p, int tca_id, struct nlmsghdr *n)
 323 {
 324         begin_argc = ematch_argc = *argc_p;
 325         begin_argv = ematch_argv = *argv_p;
 326
 327         if (ematch_parse()) {
 328                 int err = em_parse_error(EINVAL, NULL, NULL, NULL,
 329                     "Parse error");
 330                 free_ematch_err();
 331                 return err;
 332         }
 333
 334         free_ematch_err();
 335
 336         /* undo look ahead by parser */
 337         ematch_argc++;
 338         ematch_argv--;
 339
 340         if (ematch_root) {
 341                 struct rtattr *tail, *tail_list;
 342
 343                 struct tcf_ematch_tree_hdr hdr = {
 344                         .nmatches = flatten_tree(ematch_root, ematch_root),
 345                         .progid = TCF_EM_PROG_TC
 346                 };
 347
 348                 tail = NLMSG_TAIL(n);
 349                 addattr_l(n, MAX_MSG, tca_id, NULL, 0);
 350                 addattr_l(n, MAX_MSG, TCA_EMATCH_TREE_HDR, &hdr, sizeof(hdr));
 351
 352                 tail_list = NLMSG_TAIL(n);
 353                 addattr_l(n, MAX_MSG, TCA_EMATCH_TREE_LIST, NULL, 0);
 354
 355                 if (parse_tree(n, ematch_root) < 0)
 356                         return -1;
 357
 358                 tail_list->rta_len = (void*) NLMSG_TAIL(n) - (void*) tail_list;
 359                 tail->rta_len = (void*) NLMSG_TAIL(n) - (void*) tail;
 360         }
 361
 362         *argc_p = ematch_argc;
 363         *argv_p = ematch_argv;
 364
 365         return 0;
 366 }
 367
 368 static int print_ematch_seq(FILE *fd, struct rtattr **tb, int start,
 369                             int prefix)
 370 {
 371         int n, i = start;
 372         struct tcf_ematch_hdr *hdr;
 373         int dlen;
 374         void *data;
 375
 376         for (;;) {
 377                 if (tb[i] == NULL)
 378                         return -1;
 379
 380                 dlen = RTA_PAYLOAD(tb[i]) - sizeof(*hdr);
 381                 data = (void *) RTA_DATA(tb[i]) + sizeof(*hdr);
 382
 383                 if (dlen < 0)
 384                         return -1;
 385
 386                 hdr = RTA_DATA(tb[i]);
 387
 388                 if (hdr->flags & TCF_EM_INVERT)
 389                         fprintf(fd, "NOT ");
 390
 391                 if (hdr->kind == 0) {
 392                         __u32 ref;
 393
 394                         if (dlen < sizeof(__u32))
 395                                 return -1;
 396
 397                         ref = *(__u32 *) data;
 398                         fprintf(fd, "(\n");
 399                         for (n = 0; n <= prefix; n++)
 400                                 fprintf(fd, "  ");
 401                         if (print_ematch_seq(fd, tb, ref + 1, prefix + 1) < 0)
 402                                 return -1;
 403                         for (n = 0; n < prefix; n++)
 404                                 fprintf(fd, "  ");
 405                         fprintf(fd, ") ");
 406
 407                 } else {
 408                         struct ematch_util *e;
 409
 410                         e = get_ematch_kind_num(hdr->kind);
 411                         if (e == NULL)
 412                                 fprintf(fd, "[unknown ematch %d]\n",
 413                                     hdr->kind);
 414                         else {
 415                                 fprintf(fd, "%s(", e->kind);
 416                                 if (e->print_eopt(fd, hdr, data, dlen) < 0)
 417                                         return -1;
 418                                 fprintf(fd, ")\n");
 419                         }
 420                         if (hdr->flags & TCF_EM_REL_MASK)
 421                                 for (n = 0; n < prefix; n++)
 422                                         fprintf(fd, "  ");
 423                 }
 424
 425                 switch (hdr->flags & TCF_EM_REL_MASK) {
 426                         case TCF_EM_REL_AND:
 427                                 fprintf(fd, "AND ");
 428                                 break;
 429
 430                         case TCF_EM_REL_OR:
 431                                 fprintf(fd, "OR ");
 432                                 break;
 433
 434                         default:
 435                                 return 0;
 436                 }
 437
 438                 i++;
 439         }
 440
 441         return 0;
 442 }
 443
 444 static int print_ematch_list(FILE *fd, struct tcf_ematch_tree_hdr *hdr,
 445                              struct rtattr *rta)
 446 {
 447         int err = -1;
 448         struct rtattr **tb;
 449
 450         tb = malloc((hdr->nmatches + 1) * sizeof(struct rtattr *));
 451         if (tb == NULL)
 452                 return -1;
 453
 454         if (parse_rtattr_nested(tb, hdr->nmatches, rta) < 0)
 455                 goto errout;
 456
 457         fprintf(fd, "\n  ");
 458         if (print_ematch_seq(fd, tb, 1, 1) < 0)
 459                 goto errout;
 460
 461         err = 0;
 462 errout:
 463         free(tb);
 464         return err;
 465 }
 466
 467 int print_ematch(FILE *fd, const struct rtattr *rta)
 468 {
 469         struct rtattr *tb[TCA_EMATCH_TREE_MAX+1];
 470         struct tcf_ematch_tree_hdr *hdr;
 471
 472         if (parse_rtattr_nested(tb, TCA_EMATCH_TREE_MAX, rta) < 0)
 473                 return -1;
 474
 475         if (tb[TCA_EMATCH_TREE_HDR] == NULL) {
 476                 fprintf(stderr, "Missing ematch tree header\n");
 477                 return -1;
 478         }
 479
 480         if (tb[TCA_EMATCH_TREE_LIST] == NULL) {
 481                 fprintf(stderr, "Missing ematch tree list\n");
 482                 return -1;
 483         }
 484
 485         if (RTA_PAYLOAD(tb[TCA_EMATCH_TREE_HDR]) < sizeof(*hdr)) {
 486                 fprintf(stderr, "Ematch tree header size mismatch\n");
 487                 return -1;
 488         }
 489
 490         hdr = RTA_DATA(tb[TCA_EMATCH_TREE_HDR]);
 491
 492         return print_ematch_list(fd, hdr, tb[TCA_EMATCH_TREE_LIST]);
 493 }