net/sched/act_pedit.c

   1 /*
   2  * net/sched/act_pedit.c        Generic packet editor
   3  *
   4  *              This program is free software; you can redistribute 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:     Jamal Hadi Salim (2002-4)
  10  */
  11
  12 #include <linux/types.h>
  13 #include <linux/kernel.h>
  14 #include <linux/string.h>
  15 #include <linux/errno.h>
  16 #include <linux/skbuff.h>
  17 #include <linux/rtnetlink.h>
  18 #include <linux/module.h>
  19 #include <linux/init.h>
  20 #include <linux/slab.h>
  21 #include <net/netlink.h>
  22 #include <net/pkt_sched.h>
  23 #include <linux/tc_act/tc_pedit.h>
  24 #include <net/tc_act/tc_pedit.h>
  25 #include <uapi/linux/tc_act/tc_pedit.h>
  26
  27 static unsigned int pedit_net_id;
  28 static struct tc_action_ops act_pedit_ops;
  29
  30 static const struct nla_policy pedit_policy[TCA_PEDIT_MAX + 1] = {
  31         [TCA_PEDIT_PARMS]       = { .len = sizeof(struct tc_pedit) },
  32         [TCA_PEDIT_KEYS_EX]   = { .type = NLA_NESTED },
  33 };
  34
  35 static const struct nla_policy pedit_key_ex_policy[TCA_PEDIT_KEY_EX_MAX + 1] = {
  36         [TCA_PEDIT_KEY_EX_HTYPE]  = { .type = NLA_U16 },
  37         [TCA_PEDIT_KEY_EX_CMD]    = { .type = NLA_U16 },
  38 };
  39
  40 static struct tcf_pedit_key_ex *tcf_pedit_keys_ex_parse(struct nlattr *nla,
  41                                                         u8 n)
  42 {
  43         struct tcf_pedit_key_ex *keys_ex;
  44         struct tcf_pedit_key_ex *k;
  45         const struct nlattr *ka;
  46         int err = -EINVAL;
  47         int rem;
  48
  49         if (!nla)
  50                 return NULL;
  51
  52         keys_ex = kcalloc(n, sizeof(*k), GFP_KERNEL);
  53         if (!keys_ex)
  54                 return ERR_PTR(-ENOMEM);
  55
  56         k = keys_ex;
  57
  58         nla_for_each_nested(ka, nla, rem) {
  59                 struct nlattr *tb[TCA_PEDIT_KEY_EX_MAX + 1];
  60
  61                 if (!n) {
  62                         err = -EINVAL;
  63                         goto err_out;
  64                 }
  65                 n--;
  66
  67                 if (nla_type(ka) != TCA_PEDIT_KEY_EX) {
  68                         err = -EINVAL;
  69                         goto err_out;
  70                 }
  71
  72                 err = nla_parse_nested(tb, TCA_PEDIT_KEY_EX_MAX, ka,
  73                                        pedit_key_ex_policy, NULL);
  74                 if (err)
  75                         goto err_out;
  76
  77                 if (!tb[TCA_PEDIT_KEY_EX_HTYPE] ||
  78                     !tb[TCA_PEDIT_KEY_EX_CMD]) {
  79                         err = -EINVAL;
  80                         goto err_out;
  81                 }
  82
  83                 k->htype = nla_get_u16(tb[TCA_PEDIT_KEY_EX_HTYPE]);
  84                 k->cmd = nla_get_u16(tb[TCA_PEDIT_KEY_EX_CMD]);
  85
  86                 if (k->htype > TCA_PEDIT_HDR_TYPE_MAX ||
  87                     k->cmd > TCA_PEDIT_CMD_MAX) {
  88                         err = -EINVAL;
  89                         goto err_out;
  90                 }
  91
  92                 k++;
  93         }
  94
  95         if (n) {
  96                 err = -EINVAL;
  97                 goto err_out;
  98         }
  99
 100         return keys_ex;
 101
 102 err_out:
 103         kfree(keys_ex);
 104         return ERR_PTR(err);
 105 }
 106
 107 static int tcf_pedit_key_ex_dump(struct sk_buff *skb,
 108                                  struct tcf_pedit_key_ex *keys_ex, int n)
 109 {
 110         struct nlattr *keys_start = nla_nest_start(skb, TCA_PEDIT_KEYS_EX);
 111
 112         if (!keys_start)
 113                 goto nla_failure;
 114         for (; n > 0; n--) {
 115                 struct nlattr *key_start;
 116
 117                 key_start = nla_nest_start(skb, TCA_PEDIT_KEY_EX);
 118                 if (!key_start)
 119                         goto nla_failure;
 120
 121                 if (nla_put_u16(skb, TCA_PEDIT_KEY_EX_HTYPE, keys_ex->htype) ||
 122                     nla_put_u16(skb, TCA_PEDIT_KEY_EX_CMD, keys_ex->cmd))
 123                         goto nla_failure;
 124
 125                 nla_nest_end(skb, key_start);
 126
 127                 keys_ex++;
 128         }
 129
 130         nla_nest_end(skb, keys_start);
 131
 132         return 0;
 133 nla_failure:
 134         nla_nest_cancel(skb, keys_start);
 135         return -EINVAL;
 136 }
 137
 138 static int tcf_pedit_init(struct net *net, struct nlattr *nla,
 139                           struct nlattr *est, struct tc_action **a,
 140                           int ovr, int bind, bool rtnl_held,
 141                           struct netlink_ext_ack *extack)
 142 {
 143         struct tc_action_net *tn = net_generic(net, pedit_net_id);
 144         struct nlattr *tb[TCA_PEDIT_MAX + 1];
 145         struct tc_pedit_key *keys = NULL;
 146         struct tcf_pedit_key_ex *keys_ex;
 147         struct tc_pedit *parm;
 148         struct nlattr *pattr;
 149         struct tcf_pedit *p;
 150         int ret = 0, err;
 151         int i, ksize;
 152         u32 index;
 153
 154         if (!nla) {
 155                 NL_SET_ERR_MSG_MOD(extack, "Pedit requires attributes to be passed");
 156                 return -EINVAL;
 157         }
 158
 159         err = nla_parse_nested(tb, TCA_PEDIT_MAX, nla, pedit_policy, NULL);
 160         if (err < 0)
 161                 return err;
 162
 163         pattr = tb[TCA_PEDIT_PARMS];
 164         if (!pattr)
 165                 pattr = tb[TCA_PEDIT_PARMS_EX];
 166         if (!pattr) {
 167                 NL_SET_ERR_MSG_MOD(extack, "Missing required TCA_PEDIT_PARMS or TCA_PEDIT_PARMS_EX pedit attribute");
 168                 return -EINVAL;
 169         }
 170
 171         parm = nla_data(pattr);
 172         if (!parm->nkeys) {
 173                 NL_SET_ERR_MSG_MOD(extack, "Pedit requires keys to be passed");
 174                 return -EINVAL;
 175         }
 176         ksize = parm->nkeys * sizeof(struct tc_pedit_key);
 177         if (nla_len(pattr) < sizeof(*parm) + ksize) {
 178                 NL_SET_ERR_MSG_ATTR(extack, pattr, "Length of TCA_PEDIT_PARMS or TCA_PEDIT_PARMS_EX pedit attribute is invalid");
 179                 return -EINVAL;
 180         }
 181
 182         keys_ex = tcf_pedit_keys_ex_parse(tb[TCA_PEDIT_KEYS_EX], parm->nkeys);
 183         if (IS_ERR(keys_ex))
 184                 return PTR_ERR(keys_ex);
 185
 186         index = parm->index;
 187         err = tcf_idr_check_alloc(tn, &index, a, bind);
 188         if (!err) {
 189                 ret = tcf_idr_create(tn, index, est, a,
 190                                      &act_pedit_ops, bind, false);
 191                 if (ret) {
 192                         tcf_idr_cleanup(tn, index);
 193                         goto out_free;
 194                 }
 195                 ret = ACT_P_CREATED;
 196         } else if (err > 0) {
 197                 if (bind)
 198                         goto out_free;
 199                 if (!ovr) {
 200                         ret = -EEXIST;
 201                         goto out_release;
 202                 }
 203         } else {
 204                 ret = err;
 205                 goto out_free;
 206         }
 207
 208         p = to_pedit(*a);
 209         spin_lock_bh(&p->tcf_lock);
 210
 211         if (ret == ACT_P_CREATED ||
 212             (p->tcfp_nkeys && p->tcfp_nkeys != parm->nkeys)) {
 213                 keys = kmalloc(ksize, GFP_ATOMIC);
 214                 if (!keys) {
 215                         spin_unlock_bh(&p->tcf_lock);
 216                         ret = -ENOMEM;
 217                         goto out_release;
 218                 }
 219                 kfree(p->tcfp_keys);
 220                 p->tcfp_keys = keys;
 221                 p->tcfp_nkeys = parm->nkeys;
 222         }
 223         memcpy(p->tcfp_keys, parm->keys, ksize);
 224         p->tcfp_off_max_hint = 0;
 225         for (i = 0; i < p->tcfp_nkeys; ++i) {
 226                 u32 cur = p->tcfp_keys[i].off;
 227
 228                 /* sanitize the shift value for any later use */
 229                 p->tcfp_keys[i].shift = min_t(size_t, BITS_PER_TYPE(int) - 1,
 230                                               p->tcfp_keys[i].shift);
 231
 232                 /* The AT option can read a single byte, we can bound the actual
 233                  * value with uchar max.
 234                  */
 235                 cur += (0xff & p->tcfp_keys[i].offmask) >> p->tcfp_keys[i].shift;
 236
 237                 /* Each key touches 4 bytes starting from the computed offset */
 238                 p->tcfp_off_max_hint = max(p->tcfp_off_max_hint, cur + 4);
 239         }
 240
 241         p->tcfp_flags = parm->flags;
 242         p->tcf_action = parm->action;
 243
 244         kfree(p->tcfp_keys_ex);
 245         p->tcfp_keys_ex = keys_ex;
 246
 247         spin_unlock_bh(&p->tcf_lock);
 248         if (ret == ACT_P_CREATED)
 249                 tcf_idr_insert(tn, *a);
 250         return ret;
 251
 252 out_release:
 253         tcf_idr_release(*a, bind);
 254 out_free:
 255         kfree(keys_ex);
 256         return ret;
 257
 258 }
 259
 260 static void tcf_pedit_cleanup(struct tc_action *a)
 261 {
 262         struct tcf_pedit *p = to_pedit(a);
 263         struct tc_pedit_key *keys = p->tcfp_keys;
 264
 265         kfree(keys);
 266         kfree(p->tcfp_keys_ex);
 267 }
 268
 269 static bool offset_valid(struct sk_buff *skb, int offset)
 270 {
 271         if (offset > 0 && offset > skb->len)
 272                 return false;
 273
 274         if  (offset < 0 && -offset > skb_headroom(skb))
 275                 return false;
 276
 277         return true;
 278 }
 279
 280 static int pedit_skb_hdr_offset(struct sk_buff *skb,
 281                                 enum pedit_header_type htype, int *hoffset)
 282 {
 283         int ret = -EINVAL;
 284
 285         switch (htype) {
 286         case TCA_PEDIT_KEY_EX_HDR_TYPE_ETH:
 287                 if (skb_mac_header_was_set(skb)) {
 288                         *hoffset = skb_mac_offset(skb);
 289                         ret = 0;
 290                 }
 291                 break;
 292         case TCA_PEDIT_KEY_EX_HDR_TYPE_NETWORK:
 293         case TCA_PEDIT_KEY_EX_HDR_TYPE_IP4:
 294         case TCA_PEDIT_KEY_EX_HDR_TYPE_IP6:
 295                 *hoffset = skb_network_offset(skb);
 296                 ret = 0;
 297                 break;
 298         case TCA_PEDIT_KEY_EX_HDR_TYPE_TCP:
 299         case TCA_PEDIT_KEY_EX_HDR_TYPE_UDP:
 300                 if (skb_transport_header_was_set(skb)) {
 301                         *hoffset = skb_transport_offset(skb);
 302                         ret = 0;
 303                 }
 304                 break;
 305         default:
 306                 ret = -EINVAL;
 307                 break;
 308         }
 309
 310         return ret;
 311 }
 312
 313 static int tcf_pedit_act(struct sk_buff *skb, const struct tc_action *a,
 314                          struct tcf_result *res)
 315 {
 316         struct tcf_pedit *p = to_pedit(a);
 317         u32 max_offset;
 318         int i;
 319
 320         spin_lock(&p->tcf_lock);
 321
 322         max_offset = (skb_transport_header_was_set(skb) ?
 323                       skb_transport_offset(skb) :
 324                       skb_network_offset(skb)) +
 325                      p->tcfp_off_max_hint;
 326         if (skb_ensure_writable(skb, min(skb->len, max_offset)))
 327                 goto unlock;
 328
 329         tcf_lastuse_update(&p->tcf_tm);
 330
 331         if (p->tcfp_nkeys > 0) {
 332                 struct tc_pedit_key *tkey = p->tcfp_keys;
 333                 struct tcf_pedit_key_ex *tkey_ex = p->tcfp_keys_ex;
 334                 enum pedit_header_type htype =
 335                         TCA_PEDIT_KEY_EX_HDR_TYPE_NETWORK;
 336                 enum pedit_cmd cmd = TCA_PEDIT_KEY_EX_CMD_SET;
 337
 338                 for (i = p->tcfp_nkeys; i > 0; i--, tkey++) {
 339                         u32 *ptr, hdata;
 340                         int offset = tkey->off;
 341                         int hoffset;
 342                         u32 val;
 343                         int rc;
 344
 345                         if (tkey_ex) {
 346                                 htype = tkey_ex->htype;
 347                                 cmd = tkey_ex->cmd;
 348
 349                                 tkey_ex++;
 350                         }
 351
 352                         rc = pedit_skb_hdr_offset(skb, htype, &hoffset);
 353                         if (rc) {
 354                                 pr_info("tc action pedit bad header type specified (0x%x)\n",
 355                                         htype);
 356                                 goto bad;
 357                         }
 358
 359                         if (tkey->offmask) {
 360                                 u8 *d, _d;
 361
 362                                 if (!offset_valid(skb, hoffset + tkey->at)) {
 363                                         pr_info("tc action pedit 'at' offset %d out of bounds\n",
 364                                                 hoffset + tkey->at);
 365                                         goto bad;
 366                                 }
 367                                 d = skb_header_pointer(skb, hoffset + tkey->at,
 368                                                        sizeof(_d), &_d);
 369                                 if (!d)
 370                                         goto bad;
 371                                 offset += (*d & tkey->offmask) >> tkey->shift;
 372                         }
 373
 374                         if (offset % 4) {
 375                                 pr_info("tc action pedit offset must be on 32 bit boundaries\n");
 376                                 goto bad;
 377                         }
 378
 379                         if (!offset_valid(skb, hoffset + offset)) {
 380                                 pr_info("tc action pedit offset %d out of bounds\n",
 381                                         hoffset + offset);
 382                                 goto bad;
 383                         }
 384
 385                         ptr = skb_header_pointer(skb, hoffset + offset,
 386                                                  sizeof(hdata), &hdata);
 387                         if (!ptr)
 388                                 goto bad;
 389                         /* just do it, baby */
 390                         switch (cmd) {
 391                         case TCA_PEDIT_KEY_EX_CMD_SET:
 392                                 val = tkey->val;
 393                                 break;
 394                         case TCA_PEDIT_KEY_EX_CMD_ADD:
 395                                 val = (*ptr + tkey->val) & ~tkey->mask;
 396                                 break;
 397                         default:
 398                                 pr_info("tc action pedit bad command (%d)\n",
 399                                         cmd);
 400                                 goto bad;
 401                         }
 402
 403                         *ptr = ((*ptr & tkey->mask) ^ val);
 404                         if (ptr == &hdata)
 405                                 skb_store_bits(skb, hoffset + offset, ptr, 4);
 406                 }
 407
 408                 goto done;
 409         } else {
 410                 WARN(1, "pedit BUG: index %d\n", p->tcf_index);
 411         }
 412
 413 bad:
 414         p->tcf_qstats.overlimits++;
 415 done:
 416         bstats_update(&p->tcf_bstats, skb);
 417 unlock:
 418         spin_unlock(&p->tcf_lock);
 419         return p->tcf_action;
 420 }
 421
 422 static int tcf_pedit_dump(struct sk_buff *skb, struct tc_action *a,
 423                           int bind, int ref)
 424 {
 425         unsigned char *b = skb_tail_pointer(skb);
 426         struct tcf_pedit *p = to_pedit(a);
 427         struct tc_pedit *opt;
 428         struct tcf_t t;
 429         int s;
 430
 431         s = sizeof(*opt) + p->tcfp_nkeys * sizeof(struct tc_pedit_key);
 432
 433         /* netlink spinlocks held above us - must use ATOMIC */
 434         opt = kzalloc(s, GFP_ATOMIC);
 435         if (unlikely(!opt))
 436                 return -ENOBUFS;
 437
 438         spin_lock_bh(&p->tcf_lock);
 439         memcpy(opt->keys, p->tcfp_keys,
 440                p->tcfp_nkeys * sizeof(struct tc_pedit_key));
 441         opt->index = p->tcf_index;
 442         opt->nkeys = p->tcfp_nkeys;
 443         opt->flags = p->tcfp_flags;
 444         opt->action = p->tcf_action;
 445         opt->refcnt = refcount_read(&p->tcf_refcnt) - ref;
 446         opt->bindcnt = atomic_read(&p->tcf_bindcnt) - bind;
 447
 448         if (p->tcfp_keys_ex) {
 449                 if (tcf_pedit_key_ex_dump(skb,
 450                                           p->tcfp_keys_ex,
 451                                           p->tcfp_nkeys))
 452                         goto nla_put_failure;
 453
 454                 if (nla_put(skb, TCA_PEDIT_PARMS_EX, s, opt))
 455                         goto nla_put_failure;
 456         } else {
 457                 if (nla_put(skb, TCA_PEDIT_PARMS, s, opt))
 458                         goto nla_put_failure;
 459         }
 460
 461         tcf_tm_dump(&t, &p->tcf_tm);
 462         if (nla_put_64bit(skb, TCA_PEDIT_TM, sizeof(t), &t, TCA_PEDIT_PAD))
 463                 goto nla_put_failure;
 464         spin_unlock_bh(&p->tcf_lock);
 465
 466         kfree(opt);
 467         return skb->len;
 468
 469 nla_put_failure:
 470         spin_unlock_bh(&p->tcf_lock);
 471         nlmsg_trim(skb, b);
 472         kfree(opt);
 473         return -1;
 474 }
 475
 476 static int tcf_pedit_walker(struct net *net, struct sk_buff *skb,
 477                             struct netlink_callback *cb, int type,
 478                             const struct tc_action_ops *ops,
 479                             struct netlink_ext_ack *extack)
 480 {
 481         struct tc_action_net *tn = net_generic(net, pedit_net_id);
 482
 483         return tcf_generic_walker(tn, skb, cb, type, ops, extack);
 484 }
 485
 486 static int tcf_pedit_search(struct net *net, struct tc_action **a, u32 index,
 487                             struct netlink_ext_ack *extack)
 488 {
 489         struct tc_action_net *tn = net_generic(net, pedit_net_id);
 490
 491         return tcf_idr_search(tn, a, index);
 492 }
 493
 494 static struct tc_action_ops act_pedit_ops = {
 495         .kind           =       "pedit",
 496         .type           =       TCA_ACT_PEDIT,
 497         .owner          =       THIS_MODULE,
 498         .act            =       tcf_pedit_act,
 499         .dump           =       tcf_pedit_dump,
 500         .cleanup        =       tcf_pedit_cleanup,
 501         .init           =       tcf_pedit_init,
 502         .walk           =       tcf_pedit_walker,
 503         .lookup         =       tcf_pedit_search,
 504         .size           =       sizeof(struct tcf_pedit),
 505 };
 506
 507 static __net_init int pedit_init_net(struct net *net)
 508 {
 509         struct tc_action_net *tn = net_generic(net, pedit_net_id);
 510
 511         return tc_action_net_init(net, tn, &act_pedit_ops);
 512 }
 513
 514 static void __net_exit pedit_exit_net(struct list_head *net_list)
 515 {
 516         tc_action_net_exit(net_list, pedit_net_id);
 517 }
 518
 519 static struct pernet_operations pedit_net_ops = {
 520         .init = pedit_init_net,
 521         .exit_batch = pedit_exit_net,
 522         .id   = &pedit_net_id,
 523         .size = sizeof(struct tc_action_net),
 524 };
 525
 526 MODULE_AUTHOR("Jamal Hadi Salim(2002-4)");
 527 MODULE_DESCRIPTION("Generic Packet Editor actions");
 528 MODULE_LICENSE("GPL");
 529
 530 static int __init pedit_init_module(void)
 531 {
 532         return tcf_register_action(&act_pedit_ops, &pedit_net_ops);
 533 }
 534
 535 static void __exit pedit_cleanup_module(void)
 536 {
 537         tcf_unregister_action(&act_pedit_ops, &pedit_net_ops);
 538 }
 539
 540 module_init(pedit_init_module);
 541 module_exit(pedit_cleanup_module);