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 #include <net/ip.h>
  25
  26 #include <linux/netfilter_ipv4/ip_tables.h>
  27
  28
  29 static struct tc_action_ops act_ipt_ops;
  30 static struct tc_action_ops act_xt_ops;
  31
  32 static int ipt_init_target(struct net *net, struct xt_entry_target *t,
  33                            char *table, unsigned int hook)
  34 {
  35         struct xt_tgchk_param par;
  36         struct xt_target *target;
  37         struct ipt_entry e = {};
  38         int ret = 0;
  39
  40         target = xt_request_find_target(AF_INET, t->u.user.name,
  41                                         t->u.user.revision);
  42         if (IS_ERR(target))
  43                 return PTR_ERR(target);
  44
  45         t->u.kernel.target = target;
  46         memset(&par, 0, sizeof(par));
  47         par.net       = net;
  48         par.table     = table;
  49         par.entryinfo = &e;
  50         par.target    = target;
  51         par.targinfo  = t->data;
  52         par.hook_mask = 1 << hook;
  53         par.family    = NFPROTO_IPV4;
  54
  55         ret = xt_check_target(&par, t->u.target_size - sizeof(*t), 0, false);
  56         if (ret < 0) {
  57                 module_put(t->u.kernel.target->me);
  58                 return ret;
  59         }
  60         return 0;
  61 }
  62
  63 static void ipt_destroy_target(struct xt_entry_target *t, struct net *net)
  64 {
  65         struct xt_tgdtor_param par = {
  66                 .target   = t->u.kernel.target,
  67                 .targinfo = t->data,
  68                 .family   = NFPROTO_IPV4,
  69                 .net      = net,
  70         };
  71         if (par.target->destroy != NULL)
  72                 par.target->destroy(&par);
  73         module_put(par.target->me);
  74 }
  75
  76 static void tcf_ipt_release(struct tc_action *a)
  77 {
  78         struct tcf_ipt *ipt = to_ipt(a);
  79
  80         if (ipt->tcfi_t) {
  81                 ipt_destroy_target(ipt->tcfi_t, a->idrinfo->net);
  82                 kfree(ipt->tcfi_t);
  83         }
  84         kfree(ipt->tcfi_tname);
  85 }
  86
  87 static const struct nla_policy ipt_policy[TCA_IPT_MAX + 1] = {
  88         [TCA_IPT_TABLE] = { .type = NLA_STRING, .len = IFNAMSIZ },
  89         [TCA_IPT_HOOK]  = NLA_POLICY_RANGE(NLA_U32, NF_INET_PRE_ROUTING,
  90                                            NF_INET_NUMHOOKS),
  91         [TCA_IPT_INDEX] = { .type = NLA_U32 },
  92         [TCA_IPT_TARG]  = { .len = sizeof(struct xt_entry_target) },
  93 };
  94
  95 static int __tcf_ipt_init(struct net *net, unsigned int id, struct nlattr *nla,
  96                           struct nlattr *est, struct tc_action **a,
  97                           const struct tc_action_ops *ops,
  98                           struct tcf_proto *tp, u32 flags)
  99 {
 100         struct tc_action_net *tn = net_generic(net, id);
 101         bool bind = flags & TCA_ACT_FLAGS_BIND;
 102         struct nlattr *tb[TCA_IPT_MAX + 1];
 103         struct tcf_ipt *ipt;
 104         struct xt_entry_target *td, *t;
 105         char *tname;
 106         bool exists = false;
 107         int ret = 0, err;
 108         u32 hook = 0;
 109         u32 index = 0;
 110
 111         if (nla == NULL)
 112                 return -EINVAL;
 113
 114         err = nla_parse_nested_deprecated(tb, TCA_IPT_MAX, nla, ipt_policy,
 115                                           NULL);
 116         if (err < 0)
 117                 return err;
 118
 119         if (tb[TCA_IPT_INDEX] != NULL)
 120                 index = nla_get_u32(tb[TCA_IPT_INDEX]);
 121
 122         err = tcf_idr_check_alloc(tn, &index, a, bind);
 123         if (err < 0)
 124                 return err;
 125         exists = err;
 126         if (exists && bind)
 127                 return 0;
 128
 129         if (tb[TCA_IPT_HOOK] == NULL || tb[TCA_IPT_TARG] == NULL) {
 130                 if (exists)
 131                         tcf_idr_release(*a, bind);
 132                 else
 133                         tcf_idr_cleanup(tn, index);
 134                 return -EINVAL;
 135         }
 136
 137         td = (struct xt_entry_target *)nla_data(tb[TCA_IPT_TARG]);
 138         if (nla_len(tb[TCA_IPT_TARG]) != td->u.target_size) {
 139                 if (exists)
 140                         tcf_idr_release(*a, bind);
 141                 else
 142                         tcf_idr_cleanup(tn, index);
 143                 return -EINVAL;
 144         }
 145
 146         if (!exists) {
 147                 ret = tcf_idr_create(tn, index, est, a, ops, bind,
 148                                      false, flags);
 149                 if (ret) {
 150                         tcf_idr_cleanup(tn, index);
 151                         return ret;
 152                 }
 153                 ret = ACT_P_CREATED;
 154         } else {
 155                 if (bind)/* dont override defaults */
 156                         return 0;
 157
 158                 if (!(flags & TCA_ACT_FLAGS_REPLACE)) {
 159                         tcf_idr_release(*a, bind);
 160                         return -EEXIST;
 161                 }
 162         }
 163
 164         err = -EINVAL;
 165         hook = nla_get_u32(tb[TCA_IPT_HOOK]);
 166         switch (hook) {
 167         case NF_INET_PRE_ROUTING:
 168                 break;
 169         case NF_INET_POST_ROUTING:
 170                 break;
 171         default:
 172                 goto err1;
 173         }
 174
 175         if (tb[TCA_IPT_TABLE]) {
 176                 /* mangle only for now */
 177                 if (nla_strcmp(tb[TCA_IPT_TABLE], "mangle"))
 178                         goto err1;
 179         }
 180
 181         tname = kstrdup("mangle", GFP_KERNEL);
 182         if (unlikely(!tname))
 183                 goto err1;
 184
 185         t = kmemdup(td, td->u.target_size, GFP_KERNEL);
 186         if (unlikely(!t))
 187                 goto err2;
 188
 189         err = ipt_init_target(net, t, tname, hook);
 190         if (err < 0)
 191                 goto err3;
 192
 193         ipt = to_ipt(*a);
 194
 195         spin_lock_bh(&ipt->tcf_lock);
 196         if (ret != ACT_P_CREATED) {
 197                 ipt_destroy_target(ipt->tcfi_t, net);
 198                 kfree(ipt->tcfi_tname);
 199                 kfree(ipt->tcfi_t);
 200         }
 201         ipt->tcfi_tname = tname;
 202         ipt->tcfi_t     = t;
 203         ipt->tcfi_hook  = hook;
 204         spin_unlock_bh(&ipt->tcf_lock);
 205         return ret;
 206
 207 err3:
 208         kfree(t);
 209 err2:
 210         kfree(tname);
 211 err1:
 212         tcf_idr_release(*a, bind);
 213         return err;
 214 }
 215
 216 static int tcf_ipt_init(struct net *net, struct nlattr *nla,
 217                         struct nlattr *est, struct tc_action **a,
 218                         struct tcf_proto *tp,
 219                         u32 flags, struct netlink_ext_ack *extack)
 220 {
 221         return __tcf_ipt_init(net, act_ipt_ops.net_id, nla, est,
 222                               a, &act_ipt_ops, tp, flags);
 223 }
 224
 225 static int tcf_xt_init(struct net *net, struct nlattr *nla,
 226                        struct nlattr *est, struct tc_action **a,
 227                        struct tcf_proto *tp,
 228                        u32 flags, struct netlink_ext_ack *extack)
 229 {
 230         return __tcf_ipt_init(net, act_xt_ops.net_id, nla, est,
 231                               a, &act_xt_ops, tp, flags);
 232 }
 233
 234 static bool tcf_ipt_act_check(struct sk_buff *skb)
 235 {
 236         const struct iphdr *iph;
 237         unsigned int nhoff, len;
 238
 239         if (!pskb_may_pull(skb, sizeof(struct iphdr)))
 240                 return false;
 241
 242         nhoff = skb_network_offset(skb);
 243         iph = ip_hdr(skb);
 244         if (iph->ihl < 5 || iph->version != 4)
 245                 return false;
 246
 247         len = skb_ip_totlen(skb);
 248         if (skb->len < nhoff + len || len < (iph->ihl * 4u))
 249                 return false;
 250
 251         return pskb_may_pull(skb, iph->ihl * 4u);
 252 }
 253
 254 TC_INDIRECT_SCOPE int tcf_ipt_act(struct sk_buff *skb,
 255                                   const struct tc_action *a,
 256                                   struct tcf_result *res)
 257 {
 258         char saved_cb[sizeof_field(struct sk_buff, cb)];
 259         int ret = 0, result = 0;
 260         struct tcf_ipt *ipt = to_ipt(a);
 261         struct xt_action_param par;
 262         struct nf_hook_state state = {
 263                 .net    = dev_net(skb->dev),
 264                 .in     = skb->dev,
 265                 .hook   = ipt->tcfi_hook,
 266                 .pf     = NFPROTO_IPV4,
 267         };
 268
 269         if (skb_protocol(skb, false) != htons(ETH_P_IP))
 270                 return TC_ACT_UNSPEC;
 271
 272         if (skb_unclone(skb, GFP_ATOMIC))
 273                 return TC_ACT_UNSPEC;
 274
 275         if (!tcf_ipt_act_check(skb))
 276                 return TC_ACT_UNSPEC;
 277
 278         if (state.hook == NF_INET_POST_ROUTING) {
 279                 if (!skb_dst(skb))
 280                         return TC_ACT_UNSPEC;
 281
 282                 state.out = skb->dev;
 283         }
 284
 285         memcpy(saved_cb, skb->cb, sizeof(saved_cb));
 286
 287         spin_lock(&ipt->tcf_lock);
 288
 289         tcf_lastuse_update(&ipt->tcf_tm);
 290         bstats_update(&ipt->tcf_bstats, skb);
 291
 292         /* yes, we have to worry about both in and out dev
 293          * worry later - danger - this API seems to have changed
 294          * from earlier kernels
 295          */
 296         par.state    = &state;
 297         par.target   = ipt->tcfi_t->u.kernel.target;
 298         par.targinfo = ipt->tcfi_t->data;
 299
 300         memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
 301
 302         ret = par.target->target(skb, &par);
 303
 304         switch (ret) {
 305         case NF_ACCEPT:
 306                 result = TC_ACT_OK;
 307                 break;
 308         case NF_DROP:
 309                 result = TC_ACT_SHOT;
 310                 ipt->tcf_qstats.drops++;
 311                 break;
 312         case XT_CONTINUE:
 313                 result = TC_ACT_PIPE;
 314                 break;
 315         default:
 316                 net_notice_ratelimited("tc filter: Bogus netfilter code %d assume ACCEPT\n",
 317                                        ret);
 318                 result = TC_ACT_OK;
 319                 break;
 320         }
 321         spin_unlock(&ipt->tcf_lock);
 322
 323         memcpy(skb->cb, saved_cb, sizeof(skb->cb));
 324
 325         return result;
 326
 327 }
 328
 329 static int tcf_ipt_dump(struct sk_buff *skb, struct tc_action *a, int bind,
 330                         int ref)
 331 {
 332         unsigned char *b = skb_tail_pointer(skb);
 333         struct tcf_ipt *ipt = to_ipt(a);
 334         struct xt_entry_target *t;
 335         struct tcf_t tm;
 336         struct tc_cnt c;
 337
 338         /* for simple targets kernel size == user size
 339          * user name = target name
 340          * for foolproof you need to not assume this
 341          */
 342
 343         spin_lock_bh(&ipt->tcf_lock);
 344         t = kmemdup(ipt->tcfi_t, ipt->tcfi_t->u.user.target_size, GFP_ATOMIC);
 345         if (unlikely(!t))
 346                 goto nla_put_failure;
 347
 348         c.bindcnt = atomic_read(&ipt->tcf_bindcnt) - bind;
 349         c.refcnt = refcount_read(&ipt->tcf_refcnt) - ref;
 350         strcpy(t->u.user.name, ipt->tcfi_t->u.kernel.target->name);
 351
 352         if (nla_put(skb, TCA_IPT_TARG, ipt->tcfi_t->u.user.target_size, t) ||
 353             nla_put_u32(skb, TCA_IPT_INDEX, ipt->tcf_index) ||
 354             nla_put_u32(skb, TCA_IPT_HOOK, ipt->tcfi_hook) ||
 355             nla_put(skb, TCA_IPT_CNT, sizeof(struct tc_cnt), &c) ||
 356             nla_put_string(skb, TCA_IPT_TABLE, ipt->tcfi_tname))
 357                 goto nla_put_failure;
 358
 359         tcf_tm_dump(&tm, &ipt->tcf_tm);
 360         if (nla_put_64bit(skb, TCA_IPT_TM, sizeof(tm), &tm, TCA_IPT_PAD))
 361                 goto nla_put_failure;
 362
 363         spin_unlock_bh(&ipt->tcf_lock);
 364         kfree(t);
 365         return skb->len;
 366
 367 nla_put_failure:
 368         spin_unlock_bh(&ipt->tcf_lock);
 369         nlmsg_trim(skb, b);
 370         kfree(t);
 371         return -1;
 372 }
 373
 374 static struct tc_action_ops act_ipt_ops = {
 375         .kind           =       "ipt",
 376         .id             =       TCA_ID_IPT,
 377         .owner          =       THIS_MODULE,
 378         .act            =       tcf_ipt_act,
 379         .dump           =       tcf_ipt_dump,
 380         .cleanup        =       tcf_ipt_release,
 381         .init           =       tcf_ipt_init,
 382         .size           =       sizeof(struct tcf_ipt),
 383 };
 384
 385 static __net_init int ipt_init_net(struct net *net)
 386 {
 387         struct tc_action_net *tn = net_generic(net, act_ipt_ops.net_id);
 388
 389         return tc_action_net_init(net, tn, &act_ipt_ops);
 390 }
 391
 392 static void __net_exit ipt_exit_net(struct list_head *net_list)
 393 {
 394         tc_action_net_exit(net_list, act_ipt_ops.net_id);
 395 }
 396
 397 static struct pernet_operations ipt_net_ops = {
 398         .init = ipt_init_net,
 399         .exit_batch = ipt_exit_net,
 400         .id   = &act_ipt_ops.net_id,
 401         .size = sizeof(struct tc_action_net),
 402 };
 403
 404 static struct tc_action_ops act_xt_ops = {
 405         .kind           =       "xt",
 406         .id             =       TCA_ID_XT,
 407         .owner          =       THIS_MODULE,
 408         .act            =       tcf_ipt_act,
 409         .dump           =       tcf_ipt_dump,
 410         .cleanup        =       tcf_ipt_release,
 411         .init           =       tcf_xt_init,
 412         .size           =       sizeof(struct tcf_ipt),
 413 };
 414
 415 static __net_init int xt_init_net(struct net *net)
 416 {
 417         struct tc_action_net *tn = net_generic(net, act_xt_ops.net_id);
 418
 419         return tc_action_net_init(net, tn, &act_xt_ops);
 420 }
 421
 422 static void __net_exit xt_exit_net(struct list_head *net_list)
 423 {
 424         tc_action_net_exit(net_list, act_xt_ops.net_id);
 425 }
 426
 427 static struct pernet_operations xt_net_ops = {
 428         .init = xt_init_net,
 429         .exit_batch = xt_exit_net,
 430         .id   = &act_xt_ops.net_id,
 431         .size = sizeof(struct tc_action_net),
 432 };
 433
 434 MODULE_AUTHOR("Jamal Hadi Salim(2002-13)");
 435 MODULE_DESCRIPTION("Iptables target actions");
 436 MODULE_LICENSE("GPL");
 437 MODULE_ALIAS("act_xt");
 438
 439 static int __init ipt_init_module(void)
 440 {
 441         int ret1, ret2;
 442
 443         ret1 = tcf_register_action(&act_xt_ops, &xt_net_ops);
 444         if (ret1 < 0)
 445                 pr_err("Failed to load xt action\n");
 446
 447         ret2 = tcf_register_action(&act_ipt_ops, &ipt_net_ops);
 448         if (ret2 < 0)
 449                 pr_err("Failed to load ipt action\n");
 450
 451         if (ret1 < 0 && ret2 < 0) {
 452                 return ret1;
 453         } else
 454                 return 0;
 455 }
 456
 457 static void __exit ipt_cleanup_module(void)
 458 {
 459         tcf_unregister_action(&act_ipt_ops, &ipt_net_ops);
 460         tcf_unregister_action(&act_xt_ops, &xt_net_ops);
 461 }
 462
 463 module_init(ipt_init_module);
 464 module_exit(ipt_cleanup_module);