net/netfilter/nfnetlink_acct.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * (C) 2011 Pablo Neira Ayuso <pablo@netfilter.org>
   4  * (C) 2011 Intra2net AG <https://www.intra2net.com>
   5  */
   6 #include <linux/init.h>
   7 #include <linux/module.h>
   8 #include <linux/kernel.h>
   9 #include <linux/skbuff.h>
  10 #include <linux/atomic.h>
  11 #include <linux/refcount.h>
  12 #include <linux/netlink.h>
  13 #include <linux/rculist.h>
  14 #include <linux/slab.h>
  15 #include <linux/types.h>
  16 #include <linux/errno.h>
  17 #include <net/netlink.h>
  18 #include <net/sock.h>
  19
  20 #include <linux/netfilter.h>
  21 #include <linux/netfilter/nfnetlink.h>
  22 #include <linux/netfilter/nfnetlink_acct.h>
  23
  24 MODULE_LICENSE("GPL");
  25 MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
  26 MODULE_DESCRIPTION("nfacct: Extended Netfilter accounting infrastructure");
  27
  28 struct nf_acct {
  29         atomic64_t              pkts;
  30         atomic64_t              bytes;
  31         unsigned long           flags;
  32         struct list_head        head;
  33         refcount_t              refcnt;
  34         char                    name[NFACCT_NAME_MAX];
  35         struct rcu_head         rcu_head;
  36         char                    data[];
  37 };
  38
  39 struct nfacct_filter {
  40         u32 value;
  41         u32 mask;
  42 };
  43
  44 #define NFACCT_F_QUOTA (NFACCT_F_QUOTA_PKTS | NFACCT_F_QUOTA_BYTES)
  45 #define NFACCT_OVERQUOTA_BIT    2       /* NFACCT_F_OVERQUOTA */
  46
  47 static int nfnl_acct_new(struct net *net, struct sock *nfnl,
  48                          struct sk_buff *skb, const struct nlmsghdr *nlh,
  49                          const struct nlattr * const tb[],
  50                          struct netlink_ext_ack *extack)
  51 {
  52         struct nf_acct *nfacct, *matching = NULL;
  53         char *acct_name;
  54         unsigned int size = 0;
  55         u32 flags = 0;
  56
  57         if (!tb[NFACCT_NAME])
  58                 return -EINVAL;
  59
  60         acct_name = nla_data(tb[NFACCT_NAME]);
  61         if (strlen(acct_name) == 0)
  62                 return -EINVAL;
  63
  64         list_for_each_entry(nfacct, &net->nfnl_acct_list, head) {
  65                 if (strncmp(nfacct->name, acct_name, NFACCT_NAME_MAX) != 0)
  66                         continue;
  67
  68                 if (nlh->nlmsg_flags & NLM_F_EXCL)
  69                         return -EEXIST;
  70
  71                 matching = nfacct;
  72                 break;
  73         }
  74
  75         if (matching) {
  76                 if (nlh->nlmsg_flags & NLM_F_REPLACE) {
  77                         /* reset counters if you request a replacement. */
  78                         atomic64_set(&matching->pkts, 0);
  79                         atomic64_set(&matching->bytes, 0);
  80                         smp_mb__before_atomic();
  81                         /* reset overquota flag if quota is enabled. */
  82                         if ((matching->flags & NFACCT_F_QUOTA))
  83                                 clear_bit(NFACCT_OVERQUOTA_BIT,
  84                                           &matching->flags);
  85                         return 0;
  86                 }
  87                 return -EBUSY;
  88         }
  89
  90         if (tb[NFACCT_FLAGS]) {
  91                 flags = ntohl(nla_get_be32(tb[NFACCT_FLAGS]));
  92                 if (flags & ~NFACCT_F_QUOTA)
  93                         return -EOPNOTSUPP;
  94                 if ((flags & NFACCT_F_QUOTA) == NFACCT_F_QUOTA)
  95                         return -EINVAL;
  96                 if (flags & NFACCT_F_OVERQUOTA)
  97                         return -EINVAL;
  98                 if ((flags & NFACCT_F_QUOTA) && !tb[NFACCT_QUOTA])
  99                         return -EINVAL;
 100
 101                 size += sizeof(u64);
 102         }
 103
 104         nfacct = kzalloc(sizeof(struct nf_acct) + size, GFP_KERNEL);
 105         if (nfacct == NULL)
 106                 return -ENOMEM;
 107
 108         if (flags & NFACCT_F_QUOTA) {
 109                 u64 *quota = (u64 *)nfacct->data;
 110
 111                 *quota = be64_to_cpu(nla_get_be64(tb[NFACCT_QUOTA]));
 112                 nfacct->flags = flags;
 113         }
 114
 115         nla_strlcpy(nfacct->name, tb[NFACCT_NAME], NFACCT_NAME_MAX);
 116
 117         if (tb[NFACCT_BYTES]) {
 118                 atomic64_set(&nfacct->bytes,
 119                              be64_to_cpu(nla_get_be64(tb[NFACCT_BYTES])));
 120         }
 121         if (tb[NFACCT_PKTS]) {
 122                 atomic64_set(&nfacct->pkts,
 123                              be64_to_cpu(nla_get_be64(tb[NFACCT_PKTS])));
 124         }
 125         refcount_set(&nfacct->refcnt, 1);
 126         list_add_tail_rcu(&nfacct->head, &net->nfnl_acct_list);
 127         return 0;
 128 }
 129
 130 static int
 131 nfnl_acct_fill_info(struct sk_buff *skb, u32 portid, u32 seq, u32 type,
 132                    int event, struct nf_acct *acct)
 133 {
 134         struct nlmsghdr *nlh;
 135         struct nfgenmsg *nfmsg;
 136         unsigned int flags = portid ? NLM_F_MULTI : 0;
 137         u64 pkts, bytes;
 138         u32 old_flags;
 139
 140         event = nfnl_msg_type(NFNL_SUBSYS_ACCT, event);
 141         nlh = nlmsg_put(skb, portid, seq, event, sizeof(*nfmsg), flags);
 142         if (nlh == NULL)
 143                 goto nlmsg_failure;
 144
 145         nfmsg = nlmsg_data(nlh);
 146         nfmsg->nfgen_family = AF_UNSPEC;
 147         nfmsg->version = NFNETLINK_V0;
 148         nfmsg->res_id = 0;
 149
 150         if (nla_put_string(skb, NFACCT_NAME, acct->name))
 151                 goto nla_put_failure;
 152
 153         old_flags = acct->flags;
 154         if (type == NFNL_MSG_ACCT_GET_CTRZERO) {
 155                 pkts = atomic64_xchg(&acct->pkts, 0);
 156                 bytes = atomic64_xchg(&acct->bytes, 0);
 157                 smp_mb__before_atomic();
 158                 if (acct->flags & NFACCT_F_QUOTA)
 159                         clear_bit(NFACCT_OVERQUOTA_BIT, &acct->flags);
 160         } else {
 161                 pkts = atomic64_read(&acct->pkts);
 162                 bytes = atomic64_read(&acct->bytes);
 163         }
 164         if (nla_put_be64(skb, NFACCT_PKTS, cpu_to_be64(pkts),
 165                          NFACCT_PAD) ||
 166             nla_put_be64(skb, NFACCT_BYTES, cpu_to_be64(bytes),
 167                          NFACCT_PAD) ||
 168             nla_put_be32(skb, NFACCT_USE, htonl(refcount_read(&acct->refcnt))))
 169                 goto nla_put_failure;
 170         if (acct->flags & NFACCT_F_QUOTA) {
 171                 u64 *quota = (u64 *)acct->data;
 172
 173                 if (nla_put_be32(skb, NFACCT_FLAGS, htonl(old_flags)) ||
 174                     nla_put_be64(skb, NFACCT_QUOTA, cpu_to_be64(*quota),
 175                                  NFACCT_PAD))
 176                         goto nla_put_failure;
 177         }
 178         nlmsg_end(skb, nlh);
 179         return skb->len;
 180
 181 nlmsg_failure:
 182 nla_put_failure:
 183         nlmsg_cancel(skb, nlh);
 184         return -1;
 185 }
 186
 187 static int
 188 nfnl_acct_dump(struct sk_buff *skb, struct netlink_callback *cb)
 189 {
 190         struct net *net = sock_net(skb->sk);
 191         struct nf_acct *cur, *last;
 192         const struct nfacct_filter *filter = cb->data;
 193
 194         if (cb->args[2])
 195                 return 0;
 196
 197         last = (struct nf_acct *)cb->args[1];
 198         if (cb->args[1])
 199                 cb->args[1] = 0;
 200
 201         rcu_read_lock();
 202         list_for_each_entry_rcu(cur, &net->nfnl_acct_list, head) {
 203                 if (last) {
 204                         if (cur != last)
 205                                 continue;
 206
 207                         last = NULL;
 208                 }
 209
 210                 if (filter && (cur->flags & filter->mask) != filter->value)
 211                         continue;
 212
 213                 if (nfnl_acct_fill_info(skb, NETLINK_CB(cb->skb).portid,
 214                                        cb->nlh->nlmsg_seq,
 215                                        NFNL_MSG_TYPE(cb->nlh->nlmsg_type),
 216                                        NFNL_MSG_ACCT_NEW, cur) < 0) {
 217                         cb->args[1] = (unsigned long)cur;
 218                         break;
 219                 }
 220         }
 221         if (!cb->args[1])
 222                 cb->args[2] = 1;
 223         rcu_read_unlock();
 224         return skb->len;
 225 }
 226
 227 static int nfnl_acct_done(struct netlink_callback *cb)
 228 {
 229         kfree(cb->data);
 230         return 0;
 231 }
 232
 233 static const struct nla_policy filter_policy[NFACCT_FILTER_MAX + 1] = {
 234         [NFACCT_FILTER_MASK]    = { .type = NLA_U32 },
 235         [NFACCT_FILTER_VALUE]   = { .type = NLA_U32 },
 236 };
 237
 238 static int nfnl_acct_start(struct netlink_callback *cb)
 239 {
 240         const struct nlattr *const attr = cb->data;
 241         struct nlattr *tb[NFACCT_FILTER_MAX + 1];
 242         struct nfacct_filter *filter;
 243         int err;
 244
 245         if (!attr)
 246                 return 0;
 247
 248         err = nla_parse_nested_deprecated(tb, NFACCT_FILTER_MAX, attr,
 249                                           filter_policy, NULL);
 250         if (err < 0)
 251                 return err;
 252
 253         if (!tb[NFACCT_FILTER_MASK] || !tb[NFACCT_FILTER_VALUE])
 254                 return -EINVAL;
 255
 256         filter = kzalloc(sizeof(struct nfacct_filter), GFP_KERNEL);
 257         if (!filter)
 258                 return -ENOMEM;
 259
 260         filter->mask = ntohl(nla_get_be32(tb[NFACCT_FILTER_MASK]));
 261         filter->value = ntohl(nla_get_be32(tb[NFACCT_FILTER_VALUE]));
 262         cb->data = filter;
 263
 264         return 0;
 265 }
 266
 267 static int nfnl_acct_get(struct net *net, struct sock *nfnl,
 268                          struct sk_buff *skb, const struct nlmsghdr *nlh,
 269                          const struct nlattr * const tb[],
 270                          struct netlink_ext_ack *extack)
 271 {
 272         int ret = -ENOENT;
 273         struct nf_acct *cur;
 274         char *acct_name;
 275
 276         if (nlh->nlmsg_flags & NLM_F_DUMP) {
 277                 struct netlink_dump_control c = {
 278                         .dump = nfnl_acct_dump,
 279                         .start = nfnl_acct_start,
 280                         .done = nfnl_acct_done,
 281                         .data = (void *)tb[NFACCT_FILTER],
 282                 };
 283
 284                 return netlink_dump_start(nfnl, skb, nlh, &c);
 285         }
 286
 287         if (!tb[NFACCT_NAME])
 288                 return -EINVAL;
 289         acct_name = nla_data(tb[NFACCT_NAME]);
 290
 291         list_for_each_entry(cur, &net->nfnl_acct_list, head) {
 292                 struct sk_buff *skb2;
 293
 294                 if (strncmp(cur->name, acct_name, NFACCT_NAME_MAX)!= 0)
 295                         continue;
 296
 297                 skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 298                 if (skb2 == NULL) {
 299                         ret = -ENOMEM;
 300                         break;
 301                 }
 302
 303                 ret = nfnl_acct_fill_info(skb2, NETLINK_CB(skb).portid,
 304                                          nlh->nlmsg_seq,
 305                                          NFNL_MSG_TYPE(nlh->nlmsg_type),
 306                                          NFNL_MSG_ACCT_NEW, cur);
 307                 if (ret <= 0) {
 308                         kfree_skb(skb2);
 309                         break;
 310                 }
 311                 ret = netlink_unicast(nfnl, skb2, NETLINK_CB(skb).portid,
 312                                         MSG_DONTWAIT);
 313                 if (ret > 0)
 314                         ret = 0;
 315
 316                 /* this avoids a loop in nfnetlink. */
 317                 return ret == -EAGAIN ? -ENOBUFS : ret;
 318         }
 319         return ret;
 320 }
 321
 322 /* try to delete object, fail if it is still in use. */
 323 static int nfnl_acct_try_del(struct nf_acct *cur)
 324 {
 325         int ret = 0;
 326
 327         /* We want to avoid races with nfnl_acct_put. So only when the current
 328          * refcnt is 1, we decrease it to 0.
 329          */
 330         if (refcount_dec_if_one(&cur->refcnt)) {
 331                 /* We are protected by nfnl mutex. */
 332                 list_del_rcu(&cur->head);
 333                 kfree_rcu(cur, rcu_head);
 334         } else {
 335                 ret = -EBUSY;
 336         }
 337         return ret;
 338 }
 339
 340 static int nfnl_acct_del(struct net *net, struct sock *nfnl,
 341                          struct sk_buff *skb, const struct nlmsghdr *nlh,
 342                          const struct nlattr * const tb[],
 343                          struct netlink_ext_ack *extack)
 344 {
 345         struct nf_acct *cur, *tmp;
 346         int ret = -ENOENT;
 347         char *acct_name;
 348
 349         if (!tb[NFACCT_NAME]) {
 350                 list_for_each_entry_safe(cur, tmp, &net->nfnl_acct_list, head)
 351                         nfnl_acct_try_del(cur);
 352
 353                 return 0;
 354         }
 355         acct_name = nla_data(tb[NFACCT_NAME]);
 356
 357         list_for_each_entry(cur, &net->nfnl_acct_list, head) {
 358                 if (strncmp(cur->name, acct_name, NFACCT_NAME_MAX) != 0)
 359                         continue;
 360
 361                 ret = nfnl_acct_try_del(cur);
 362                 if (ret < 0)
 363                         return ret;
 364
 365                 break;
 366         }
 367         return ret;
 368 }
 369
 370 static const struct nla_policy nfnl_acct_policy[NFACCT_MAX+1] = {
 371         [NFACCT_NAME] = { .type = NLA_NUL_STRING, .len = NFACCT_NAME_MAX-1 },
 372         [NFACCT_BYTES] = { .type = NLA_U64 },
 373         [NFACCT_PKTS] = { .type = NLA_U64 },
 374         [NFACCT_FLAGS] = { .type = NLA_U32 },
 375         [NFACCT_QUOTA] = { .type = NLA_U64 },
 376         [NFACCT_FILTER] = {.type = NLA_NESTED },
 377 };
 378
 379 static const struct nfnl_callback nfnl_acct_cb[NFNL_MSG_ACCT_MAX] = {
 380         [NFNL_MSG_ACCT_NEW]             = { .call = nfnl_acct_new,
 381                                             .attr_count = NFACCT_MAX,
 382                                             .policy = nfnl_acct_policy },
 383         [NFNL_MSG_ACCT_GET]             = { .call = nfnl_acct_get,
 384                                             .attr_count = NFACCT_MAX,
 385                                             .policy = nfnl_acct_policy },
 386         [NFNL_MSG_ACCT_GET_CTRZERO]     = { .call = nfnl_acct_get,
 387                                             .attr_count = NFACCT_MAX,
 388                                             .policy = nfnl_acct_policy },
 389         [NFNL_MSG_ACCT_DEL]             = { .call = nfnl_acct_del,
 390                                             .attr_count = NFACCT_MAX,
 391                                             .policy = nfnl_acct_policy },
 392 };
 393
 394 static const struct nfnetlink_subsystem nfnl_acct_subsys = {
 395         .name                           = "acct",
 396         .subsys_id                      = NFNL_SUBSYS_ACCT,
 397         .cb_count                       = NFNL_MSG_ACCT_MAX,
 398         .cb                             = nfnl_acct_cb,
 399 };
 400
 401 MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_ACCT);
 402
 403 struct nf_acct *nfnl_acct_find_get(struct net *net, const char *acct_name)
 404 {
 405         struct nf_acct *cur, *acct = NULL;
 406
 407         rcu_read_lock();
 408         list_for_each_entry_rcu(cur, &net->nfnl_acct_list, head) {
 409                 if (strncmp(cur->name, acct_name, NFACCT_NAME_MAX)!= 0)
 410                         continue;
 411
 412                 if (!try_module_get(THIS_MODULE))
 413                         goto err;
 414
 415                 if (!refcount_inc_not_zero(&cur->refcnt)) {
 416                         module_put(THIS_MODULE);
 417                         goto err;
 418                 }
 419
 420                 acct = cur;
 421                 break;
 422         }
 423 err:
 424         rcu_read_unlock();
 425         return acct;
 426 }
 427 EXPORT_SYMBOL_GPL(nfnl_acct_find_get);
 428
 429 void nfnl_acct_put(struct nf_acct *acct)
 430 {
 431         if (refcount_dec_and_test(&acct->refcnt))
 432                 kfree_rcu(acct, rcu_head);
 433
 434         module_put(THIS_MODULE);
 435 }
 436 EXPORT_SYMBOL_GPL(nfnl_acct_put);
 437
 438 void nfnl_acct_update(const struct sk_buff *skb, struct nf_acct *nfacct)
 439 {
 440         atomic64_inc(&nfacct->pkts);
 441         atomic64_add(skb->len, &nfacct->bytes);
 442 }
 443 EXPORT_SYMBOL_GPL(nfnl_acct_update);
 444
 445 static void nfnl_overquota_report(struct net *net, struct nf_acct *nfacct)
 446 {
 447         int ret;
 448         struct sk_buff *skb;
 449
 450         skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_ATOMIC);
 451         if (skb == NULL)
 452                 return;
 453
 454         ret = nfnl_acct_fill_info(skb, 0, 0, NFNL_MSG_ACCT_OVERQUOTA, 0,
 455                                   nfacct);
 456         if (ret <= 0) {
 457                 kfree_skb(skb);
 458                 return;
 459         }
 460         netlink_broadcast(net->nfnl, skb, 0, NFNLGRP_ACCT_QUOTA,
 461                           GFP_ATOMIC);
 462 }
 463
 464 int nfnl_acct_overquota(struct net *net, struct nf_acct *nfacct)
 465 {
 466         u64 now;
 467         u64 *quota;
 468         int ret = NFACCT_UNDERQUOTA;
 469
 470         /* no place here if we don't have a quota */
 471         if (!(nfacct->flags & NFACCT_F_QUOTA))
 472                 return NFACCT_NO_QUOTA;
 473
 474         quota = (u64 *)nfacct->data;
 475         now = (nfacct->flags & NFACCT_F_QUOTA_PKTS) ?
 476                atomic64_read(&nfacct->pkts) : atomic64_read(&nfacct->bytes);
 477
 478         ret = now > *quota;
 479
 480         if (now >= *quota &&
 481             !test_and_set_bit(NFACCT_OVERQUOTA_BIT, &nfacct->flags)) {
 482                 nfnl_overquota_report(net, nfacct);
 483         }
 484
 485         return ret;
 486 }
 487 EXPORT_SYMBOL_GPL(nfnl_acct_overquota);
 488
 489 static int __net_init nfnl_acct_net_init(struct net *net)
 490 {
 491         INIT_LIST_HEAD(&net->nfnl_acct_list);
 492
 493         return 0;
 494 }
 495
 496 static void __net_exit nfnl_acct_net_exit(struct net *net)
 497 {
 498         struct nf_acct *cur, *tmp;
 499
 500         list_for_each_entry_safe(cur, tmp, &net->nfnl_acct_list, head) {
 501                 list_del_rcu(&cur->head);
 502
 503                 if (refcount_dec_and_test(&cur->refcnt))
 504                         kfree_rcu(cur, rcu_head);
 505         }
 506 }
 507
 508 static struct pernet_operations nfnl_acct_ops = {
 509         .init   = nfnl_acct_net_init,
 510         .exit   = nfnl_acct_net_exit,
 511 };
 512
 513 static int __init nfnl_acct_init(void)
 514 {
 515         int ret;
 516
 517         ret = register_pernet_subsys(&nfnl_acct_ops);
 518         if (ret < 0) {
 519                 pr_err("nfnl_acct_init: failed to register pernet ops\n");
 520                 goto err_out;
 521         }
 522
 523         ret = nfnetlink_subsys_register(&nfnl_acct_subsys);
 524         if (ret < 0) {
 525                 pr_err("nfnl_acct_init: cannot register with nfnetlink.\n");
 526                 goto cleanup_pernet;
 527         }
 528         return 0;
 529
 530 cleanup_pernet:
 531         unregister_pernet_subsys(&nfnl_acct_ops);
 532 err_out:
 533         return ret;
 534 }
 535
 536 static void __exit nfnl_acct_exit(void)
 537 {
 538         nfnetlink_subsys_unregister(&nfnl_acct_subsys);
 539         unregister_pernet_subsys(&nfnl_acct_ops);
 540 }
 541
 542 module_init(nfnl_acct_init);
 543 module_exit(nfnl_acct_exit);