net/sched/act_ipt.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * net/sched/act_ipt.c          iptables target interface
   4  *
   5  *TODO: Add other tables. For now we only support the ipv4 table targets
   6  *
   7  * Copyright:   Jamal Hadi Salim (2002-13)
   8  */
   9
  10 #include <linux/types.h>
  11 #include <linux/kernel.h>
  12 #include <linux/string.h>
  13 #include <linux/errno.h>
  14 #include <linux/skbuff.h>
  15 #include <linux/rtnetlink.h>
  16 #include <linux/module.h>
  17 #include <linux/init.h>
  18 #include <linux/slab.h>
  19 #include <net/netlink.h>
  20 #include <net/pkt_sched.h>
  21 #include <linux/tc_act/tc_ipt.h>
  22 #include <net/tc_act/tc_ipt.h>
  23 #include <net/tc_wrapper.h>
  24
  25 #include <linux/netfilter_ipv4/ip_tables.h>
  26
  27
  28 static struct tc_action_ops act_ipt_ops;
  29 static struct tc_action_ops act_xt_ops;
  30
  31 static int ipt_init_target(struct net *net, struct xt_entry_target *t,
  32                            char *table, unsigned int hook)
  33 {
  34         struct xt_tgchk_param par;
  35         struct xt_target *target;
  36         struct ipt_entry e = {};
  37         int ret = 0;
  38
  39         target = xt_request_find_target(AF_INET, t->u.user.name,
  40                                         t->u.user.revision);
  41         if (IS_ERR(target))
  42                 return PTR_ERR(target);
  43
  44         t->u.kernel.target = target;
  45         memset(&par, 0, sizeof(par));
  46         par.net       = net;
  47         par.table     = table;
  48         par.entryinfo = &e;
  49         par.target    = target;
  50         par.targinfo  = t->data;
  51         par.hook_mask = 1 << hook;
  52         par.family    = NFPROTO_IPV4;
  53
  54         ret = xt_check_target(&par, t->u.target_size - sizeof(*t), 0, false);
  55         if (ret < 0) {
  56                 module_put(t->u.kernel.target->me);
  57                 return ret;
  58         }
  59         return 0;
  60 }
  61
  62 static void ipt_destroy_target(struct xt_entry_target *t, struct net *net)
  63 {
  64         struct xt_tgdtor_param par = {
  65                 .target   = t->u.kernel.target,
  66                 .targinfo = t->data,
  67                 .family   = NFPROTO_IPV4,
  68                 .net      = net,
  69         };
  70         if (par.target->destroy != NULL)
  71                 par.target->destroy(&par);
  72         module_put(par.target->me);
  73 }
  74
  75 static void tcf_ipt_release(struct tc_action *a)
  76 {
  77         struct tcf_ipt *ipt = to_ipt(a);
  78
  79         if (ipt->tcfi_t) {
  80                 ipt_destroy_target(ipt->tcfi_t, a->idrinfo->net);
  81                 kfree(ipt->tcfi_t);
  82         }
  83         kfree(ipt->tcfi_tname);
  84 }
  85
  86 static const struct nla_policy ipt_policy[TCA_IPT_MAX + 1] = {
  87         [TCA_IPT_TABLE] = { .type = NLA_STRING, .len = IFNAMSIZ },
  88         [TCA_IPT_HOOK]  = NLA_POLICY_RANGE(NLA_U32, NF_INET_PRE_ROUTING,
  89                                            NF_INET_NUMHOOKS),
  90         [TCA_IPT_INDEX] = { .type = NLA_U32 },
  91         [TCA_IPT_TARG]  = { .len = sizeof(struct xt_entry_target) },
  92 };
  93
  94 static int __tcf_ipt_init(struct net *net, unsigned int id, struct nlattr *nla,
  95                           struct nlattr *est, struct tc_action **a,
  96                           const struct tc_action_ops *ops,
  97                           struct tcf_proto *tp, u32 flags)
  98 {
  99         struct tc_action_net *tn = net_generic(net, id);
 100         bool bind = flags & TCA_ACT_FLAGS_BIND;
 101         struct nlattr *tb[TCA_IPT_MAX + 1];
 102         struct tcf_ipt *ipt;
 103         struct xt_entry_target *td, *t;
 104         char *tname;
 105         bool exists = false;
 106         int ret = 0, err;
 107         u32 hook = 0;
 108         u32 index = 0;
 109
 110         if (nla == NULL)
 111                 return -EINVAL;
 112
 113         err = nla_parse_nested_deprecated(tb, TCA_IPT_MAX, nla, ipt_policy,
 114                                           NULL);
 115         if (err < 0)
 116                 return err;
 117
 118         if (tb[TCA_IPT_INDEX] != NULL)
 119                 index = nla_get_u32(tb[TCA_IPT_INDEX]);
 120
 121         err = tcf_idr_check_alloc(tn, &index, a, bind);
 122         if (err < 0)
 123                 return err;
 124         exists = err;
 125         if (exists && bind)
 126                 return 0;
 127
 128         if (tb[TCA_IPT_HOOK] == NULL || tb[TCA_IPT_TARG] == NULL) {
 129                 if (exists)
 130                         tcf_idr_release(*a, bind);
 131                 else
 132                         tcf_idr_cleanup(tn, index);
 133                 return -EINVAL;
 134         }
 135
 136         td = (struct xt_entry_target *)nla_data(tb[TCA_IPT_TARG]);
 137         if (nla_len(tb[TCA_IPT_TARG]) != td->u.target_size) {
 138                 if (exists)
 139                         tcf_idr_release(*a, bind);
 140                 else
 141                         tcf_idr_cleanup(tn, index);
 142                 return -EINVAL;
 143         }
 144
 145         if (!exists) {
 146                 ret = tcf_idr_create(tn, index, est, a, ops, bind,
 147                                      false, flags);
 148                 if (ret) {
 149                         tcf_idr_cleanup(tn, index);
 150                         return ret;
 151                 }
 152                 ret = ACT_P_CREATED;
 153         } else {
 154                 if (bind)/* dont override defaults */
 155                         return 0;
 156
 157                 if (!(flags & TCA_ACT_FLAGS_REPLACE)) {
 158                         tcf_idr_release(*a, bind);
 159                         return -EEXIST;
 160                 }
 161         }
 162
 163         err = -EINVAL;
 164         hook = nla_get_u32(tb[TCA_IPT_HOOK]);
 165         switch (hook) {
 166         case NF_INET_PRE_ROUTING:
 167                 break;
 168         case NF_INET_POST_ROUTING:
 169                 break;
 170         default:
 171                 goto err1;
 172         }
 173
 174         if (tb[TCA_IPT_TABLE]) {
 175                 /* mangle only for now */
 176                 if (nla_strcmp(tb[TCA_IPT_TABLE], "mangle"))
 177                         goto err1;
 178         }
 179
 180         tname = kstrdup("mangle", GFP_KERNEL);
 181         if (unlikely(!tname))
 182                 goto err1;
 183
 184         t = kmemdup(td, td->u.target_size, GFP_KERNEL);
 185         if (unlikely(!t))
 186                 goto err2;
 187
 188         err = ipt_init_target(net, t, tname, hook);
 189         if (err < 0)
 190                 goto err3;
 191
 192         ipt = to_ipt(*a);
 193
 194         spin_lock_bh(&ipt->tcf_lock);
 195         if (ret != ACT_P_CREATED) {
 196                 ipt_destroy_target(ipt->tcfi_t, net);
 197                 kfree(ipt->tcfi_tname);
 198                 kfree(ipt->tcfi_t);
 199         }
 200         ipt->tcfi_tname = tname;
 201         ipt->tcfi_t     = t;
 202         ipt->tcfi_hook  = hook;
 203         spin_unlock_bh(&ipt->tcf_lock);
 204         return ret;
 205
 206 err3:
 207         kfree(t);
 208 err2:
 209         kfree(tname);
 210 err1:
 211         tcf_idr_release(*a, bind);
 212         return err;
 213 }
 214
 215 static int tcf_ipt_init(struct net *net, struct nlattr *nla,
 216                         struct nlattr *est, struct tc_action **a,
 217                         struct tcf_proto *tp,
 218                         u32 flags, struct netlink_ext_ack *extack)
 219 {
 220         return __tcf_ipt_init(net, act_ipt_ops.net_id, nla, est,
 221                               a, &act_ipt_ops, tp, flags);
 222 }
 223
 224 static int tcf_xt_init(struct net *net, struct nlattr *nla,
 225                        struct nlattr *est, struct tc_action **a,
 226                        struct tcf_proto *tp,
 227                        u32 flags, struct netlink_ext_ack *extack)
 228 {
 229         return __tcf_ipt_init(net, act_xt_ops.net_id, nla, est,
 230                               a, &act_xt_ops, tp, flags);
 231 }
 232
 233 TC_INDIRECT_SCOPE int tcf_ipt_act(struct sk_buff *skb,
 234                                   const struct tc_action *a,
 235                                   struct tcf_result *res)
 236 {
 237         int ret = 0, result = 0;
 238         struct tcf_ipt *ipt = to_ipt(a);
 239         struct xt_action_param par;
 240         struct nf_hook_state state = {
 241                 .net    = dev_net(skb->dev),
 242                 .in     = skb->dev,
 243                 .hook   = ipt->tcfi_hook,
 244                 .pf     = NFPROTO_IPV4,
 245         };
 246
 247         if (skb_unclone(skb, GFP_ATOMIC))
 248                 return TC_ACT_UNSPEC;
 249
 250         spin_lock(&ipt->tcf_lock);
 251
 252         tcf_lastuse_update(&ipt->tcf_tm);
 253         bstats_update(&ipt->tcf_bstats, skb);
 254
 255         /* yes, we have to worry about both in and out dev
 256          * worry later - danger - this API seems to have changed
 257          * from earlier kernels
 258          */
 259         par.state    = &state;
 260         par.target   = ipt->tcfi_t->u.kernel.target;
 261         par.targinfo = ipt->tcfi_t->data;
 262         ret = par.target->target(skb, &par);
 263
 264         switch (ret) {
 265         case NF_ACCEPT:
 266                 result = TC_ACT_OK;
 267                 break;
 268         case NF_DROP:
 269                 result = TC_ACT_SHOT;
 270                 ipt->tcf_qstats.drops++;
 271                 break;
 272         case XT_CONTINUE:
 273                 result = TC_ACT_PIPE;
 274                 break;
 275         default:
 276                 net_notice_ratelimited("tc filter: Bogus netfilter code %d assume ACCEPT\n",
 277                                        ret);
 278                 result = TC_ACT_OK;
 279                 break;
 280         }
 281         spin_unlock(&ipt->tcf_lock);
 282         return result;
 283
 284 }
 285
 286 static int tcf_ipt_dump(struct sk_buff *skb, struct tc_action *a, int bind,
 287                         int ref)
 288 {
 289         unsigned char *b = skb_tail_pointer(skb);
 290         struct tcf_ipt *ipt = to_ipt(a);
 291         struct xt_entry_target *t;
 292         struct tcf_t tm;
 293         struct tc_cnt c;
 294
 295         /* for simple targets kernel size == user size
 296          * user name = target name
 297          * for foolproof you need to not assume this
 298          */
 299
 300         spin_lock_bh(&ipt->tcf_lock);
 301         t = kmemdup(ipt->tcfi_t, ipt->tcfi_t->u.user.target_size, GFP_ATOMIC);
 302         if (unlikely(!t))
 303                 goto nla_put_failure;
 304
 305         c.bindcnt = atomic_read(&ipt->tcf_bindcnt) - bind;
 306         c.refcnt = refcount_read(&ipt->tcf_refcnt) - ref;
 307         strcpy(t->u.user.name, ipt->tcfi_t->u.kernel.target->name);
 308
 309         if (nla_put(skb, TCA_IPT_TARG, ipt->tcfi_t->u.user.target_size, t) ||
 310             nla_put_u32(skb, TCA_IPT_INDEX, ipt->tcf_index) ||
 311             nla_put_u32(skb, TCA_IPT_HOOK, ipt->tcfi_hook) ||
 312             nla_put(skb, TCA_IPT_CNT, sizeof(struct tc_cnt), &c) ||
 313             nla_put_string(skb, TCA_IPT_TABLE, ipt->tcfi_tname))
 314                 goto nla_put_failure;
 315
 316         tcf_tm_dump(&tm, &ipt->tcf_tm);
 317         if (nla_put_64bit(skb, TCA_IPT_TM, sizeof(tm), &tm, TCA_IPT_PAD))
 318                 goto nla_put_failure;
 319
 320         spin_unlock_bh(&ipt->tcf_lock);
 321         kfree(t);
 322         return skb->len;
 323
 324 nla_put_failure:
 325         spin_unlock_bh(&ipt->tcf_lock);
 326         nlmsg_trim(skb, b);
 327         kfree(t);
 328         return -1;
 329 }
 330
 331 static struct tc_action_ops act_ipt_ops = {
 332         .kind           =       "ipt",
 333         .id             =       TCA_ID_IPT,
 334         .owner          =       THIS_MODULE,
 335         .act            =       tcf_ipt_act,
 336         .dump           =       tcf_ipt_dump,
 337         .cleanup        =       tcf_ipt_release,
 338         .init           =       tcf_ipt_init,
 339         .size           =       sizeof(struct tcf_ipt),
 340 };
 341
 342 static __net_init int ipt_init_net(struct net *net)
 343 {
 344         struct tc_action_net *tn = net_generic(net, act_ipt_ops.net_id);
 345
 346         return tc_action_net_init(net, tn, &act_ipt_ops);
 347 }
 348
 349 static void __net_exit ipt_exit_net(struct list_head *net_list)
 350 {
 351         tc_action_net_exit(net_list, act_ipt_ops.net_id);
 352 }
 353
 354 static struct pernet_operations ipt_net_ops = {
 355         .init = ipt_init_net,
 356         .exit_batch = ipt_exit_net,
 357         .id   = &act_ipt_ops.net_id,
 358         .size = sizeof(struct tc_action_net),
 359 };
 360
 361 static struct tc_action_ops act_xt_ops = {
 362         .kind           =       "xt",
 363         .id             =       TCA_ID_XT,
 364         .owner          =       THIS_MODULE,
 365         .act            =       tcf_ipt_act,
 366         .dump           =       tcf_ipt_dump,
 367         .cleanup        =       tcf_ipt_release,
 368         .init           =       tcf_xt_init,
 369         .size           =       sizeof(struct tcf_ipt),
 370 };
 371
 372 static __net_init int xt_init_net(struct net *net)
 373 {
 374         struct tc_action_net *tn = net_generic(net, act_xt_ops.net_id);
 375
 376         return tc_action_net_init(net, tn, &act_xt_ops);
 377 }
 378
 379 static void __net_exit xt_exit_net(struct list_head *net_list)
 380 {
 381         tc_action_net_exit(net_list, act_xt_ops.net_id);
 382 }
 383
 384 static struct pernet_operations xt_net_ops = {
 385         .init = xt_init_net,
 386         .exit_batch = xt_exit_net,
 387         .id   = &act_xt_ops.net_id,
 388         .size = sizeof(struct tc_action_net),
 389 };
 390
 391 MODULE_AUTHOR("Jamal Hadi Salim(2002-13)");
 392 MODULE_DESCRIPTION("Iptables target actions");
 393 MODULE_LICENSE("GPL");
 394 MODULE_ALIAS("act_xt");
 395
 396 static int __init ipt_init_module(void)
 397 {
 398         int ret1, ret2;
 399
 400         ret1 = tcf_register_action(&act_xt_ops, &xt_net_ops);
 401         if (ret1 < 0)
 402                 pr_err("Failed to load xt action\n");
 403
 404         ret2 = tcf_register_action(&act_ipt_ops, &ipt_net_ops);
 405         if (ret2 < 0)
 406                 pr_err("Failed to load ipt action\n");
 407
 408         if (ret1 < 0 && ret2 < 0) {
 409                 return ret1;
 410         } else
 411                 return 0;
 412 }
 413
 414 static void __exit ipt_cleanup_module(void)
 415 {
 416         tcf_unregister_action(&act_ipt_ops, &ipt_net_ops);
 417         tcf_unregister_action(&act_xt_ops, &xt_net_ops);
 418 }
 419
 420 module_init(ipt_init_module);
 421 module_exit(ipt_cleanup_module);