net/netfilter/nfnetlink_acct.c

   1 /*
   2  * (C) 2011 Pablo Neira Ayuso <pablo@netfilter.org>
   3  * (C) 2011 Intra2net AG <http://www.intra2net.com>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License version 2 as
   7  * published by the Free Software Foundation (or any later at your option).
   8  */
   9 #include <linux/init.h>
  10 #include <linux/module.h>
  11 #include <linux/kernel.h>
  12 #include <linux/skbuff.h>
  13 #include <linux/atomic.h>
  14 #include <linux/netlink.h>
  15 #include <linux/rculist.h>
  16 #include <linux/slab.h>
  17 #include <linux/types.h>
  18 #include <linux/errno.h>
  19 #include <net/netlink.h>
  20 #include <net/sock.h>
  21
  22 #include <linux/netfilter.h>
  23 #include <linux/netfilter/nfnetlink.h>
  24 #include <linux/netfilter/nfnetlink_acct.h>
  25
  26 MODULE_LICENSE("GPL");
  27 MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
  28 MODULE_DESCRIPTION("nfacct: Extended Netfilter accounting infrastructure");
  29
  30 static LIST_HEAD(nfnl_acct_list);
  31
  32 struct nf_acct {
  33         atomic64_t              pkts;
  34         atomic64_t              bytes;
  35         struct list_head        head;
  36         atomic_t                refcnt;
  37         char                    name[NFACCT_NAME_MAX];
  38         struct rcu_head         rcu_head;
  39 };
  40
  41 static int
  42 nfnl_acct_new(struct sock *nfnl, struct sk_buff *skb,
  43              const struct nlmsghdr *nlh, const struct nlattr * const tb[])
  44 {
  45         struct nf_acct *nfacct, *matching = NULL;
  46         char *acct_name;
  47
  48         if (!tb[NFACCT_NAME])
  49                 return -EINVAL;
  50
  51         acct_name = nla_data(tb[NFACCT_NAME]);
  52
  53         list_for_each_entry(nfacct, &nfnl_acct_list, head) {
  54                 if (strncmp(nfacct->name, acct_name, NFACCT_NAME_MAX) != 0)
  55                         continue;
  56
  57                 if (nlh->nlmsg_flags & NLM_F_EXCL)
  58                         return -EEXIST;
  59
  60                 matching = nfacct;
  61                 break;
  62         }
  63
  64         if (matching) {
  65                 if (nlh->nlmsg_flags & NLM_F_REPLACE) {
  66                         /* reset counters if you request a replacement. */
  67                         atomic64_set(&matching->pkts, 0);
  68                         atomic64_set(&matching->bytes, 0);
  69                         return 0;
  70                 }
  71                 return -EBUSY;
  72         }
  73
  74         nfacct = kzalloc(sizeof(struct nf_acct), GFP_KERNEL);
  75         if (nfacct == NULL)
  76                 return -ENOMEM;
  77
  78         strncpy(nfacct->name, nla_data(tb[NFACCT_NAME]), NFACCT_NAME_MAX);
  79
  80         if (tb[NFACCT_BYTES]) {
  81                 atomic64_set(&nfacct->bytes,
  82                              be64_to_cpu(nla_get_u64(tb[NFACCT_BYTES])));
  83         }
  84         if (tb[NFACCT_PKTS]) {
  85                 atomic64_set(&nfacct->pkts,
  86                              be64_to_cpu(nla_get_u64(tb[NFACCT_PKTS])));
  87         }
  88         atomic_set(&nfacct->refcnt, 1);
  89         list_add_tail_rcu(&nfacct->head, &nfnl_acct_list);
  90         return 0;
  91 }
  92
  93 static int
  94 nfnl_acct_fill_info(struct sk_buff *skb, u32 pid, u32 seq, u32 type,
  95                    int event, struct nf_acct *acct)
  96 {
  97         struct nlmsghdr *nlh;
  98         struct nfgenmsg *nfmsg;
  99         unsigned int flags = pid ? NLM_F_MULTI : 0;
 100         u64 pkts, bytes;
 101
 102         event |= NFNL_SUBSYS_ACCT << 8;
 103         nlh = nlmsg_put(skb, pid, seq, event, sizeof(*nfmsg), flags);
 104         if (nlh == NULL)
 105                 goto nlmsg_failure;
 106
 107         nfmsg = nlmsg_data(nlh);
 108         nfmsg->nfgen_family = AF_UNSPEC;
 109         nfmsg->version = NFNETLINK_V0;
 110         nfmsg->res_id = 0;
 111
 112         if (nla_put_string(skb, NFACCT_NAME, acct->name))
 113                 goto nla_put_failure;
 114
 115         if (type == NFNL_MSG_ACCT_GET_CTRZERO) {
 116                 pkts = atomic64_xchg(&acct->pkts, 0);
 117                 bytes = atomic64_xchg(&acct->bytes, 0);
 118         } else {
 119                 pkts = atomic64_read(&acct->pkts);
 120                 bytes = atomic64_read(&acct->bytes);
 121         }
 122         if (nla_put_be64(skb, NFACCT_PKTS, cpu_to_be64(pkts)) ||
 123             nla_put_be64(skb, NFACCT_BYTES, cpu_to_be64(bytes)) ||
 124             nla_put_be32(skb, NFACCT_USE, htonl(atomic_read(&acct->refcnt))))
 125                 goto nla_put_failure;
 126
 127         nlmsg_end(skb, nlh);
 128         return skb->len;
 129
 130 nlmsg_failure:
 131 nla_put_failure:
 132         nlmsg_cancel(skb, nlh);
 133         return -1;
 134 }
 135
 136 static int
 137 nfnl_acct_dump(struct sk_buff *skb, struct netlink_callback *cb)
 138 {
 139         struct nf_acct *cur, *last;
 140
 141         if (cb->args[2])
 142                 return 0;
 143
 144         last = (struct nf_acct *)cb->args[1];
 145         if (cb->args[1])
 146                 cb->args[1] = 0;
 147
 148         rcu_read_lock();
 149         list_for_each_entry_rcu(cur, &nfnl_acct_list, head) {
 150                 if (last && cur != last)
 151                         continue;
 152
 153                 if (nfnl_acct_fill_info(skb, NETLINK_CB(cb->skb).pid,
 154                                        cb->nlh->nlmsg_seq,
 155                                        NFNL_MSG_TYPE(cb->nlh->nlmsg_type),
 156                                        NFNL_MSG_ACCT_NEW, cur) < 0) {
 157                         cb->args[1] = (unsigned long)cur;
 158                         break;
 159                 }
 160         }
 161         if (!cb->args[1])
 162                 cb->args[2] = 1;
 163         rcu_read_unlock();
 164         return skb->len;
 165 }
 166
 167 static int
 168 nfnl_acct_get(struct sock *nfnl, struct sk_buff *skb,
 169              const struct nlmsghdr *nlh, const struct nlattr * const tb[])
 170 {
 171         int ret = -ENOENT;
 172         struct nf_acct *cur;
 173         char *acct_name;
 174
 175         if (nlh->nlmsg_flags & NLM_F_DUMP) {
 176                 struct netlink_dump_control c = {
 177                         .dump = nfnl_acct_dump,
 178                 };
 179                 return netlink_dump_start(nfnl, skb, nlh, &c);
 180         }
 181
 182         if (!tb[NFACCT_NAME])
 183                 return -EINVAL;
 184         acct_name = nla_data(tb[NFACCT_NAME]);
 185
 186         list_for_each_entry(cur, &nfnl_acct_list, head) {
 187                 struct sk_buff *skb2;
 188
 189                 if (strncmp(cur->name, acct_name, NFACCT_NAME_MAX)!= 0)
 190                         continue;
 191
 192                 skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 193                 if (skb2 == NULL) {
 194                         ret = -ENOMEM;
 195                         break;
 196                 }
 197
 198                 ret = nfnl_acct_fill_info(skb2, NETLINK_CB(skb).pid,
 199                                          nlh->nlmsg_seq,
 200                                          NFNL_MSG_TYPE(nlh->nlmsg_type),
 201                                          NFNL_MSG_ACCT_NEW, cur);
 202                 if (ret <= 0) {
 203                         kfree_skb(skb2);
 204                         break;
 205                 }
 206                 ret = netlink_unicast(nfnl, skb2, NETLINK_CB(skb).pid,
 207                                         MSG_DONTWAIT);
 208                 if (ret > 0)
 209                         ret = 0;
 210
 211                 /* this avoids a loop in nfnetlink. */
 212                 return ret == -EAGAIN ? -ENOBUFS : ret;
 213         }
 214         return ret;
 215 }
 216
 217 /* try to delete object, fail if it is still in use. */
 218 static int nfnl_acct_try_del(struct nf_acct *cur)
 219 {
 220         int ret = 0;
 221
 222         /* we want to avoid races with nfnl_acct_find_get. */
 223         if (atomic_dec_and_test(&cur->refcnt)) {
 224                 /* We are protected by nfnl mutex. */
 225                 list_del_rcu(&cur->head);
 226                 kfree_rcu(cur, rcu_head);
 227         } else {
 228                 /* still in use, restore reference counter. */
 229                 atomic_inc(&cur->refcnt);
 230                 ret = -EBUSY;
 231         }
 232         return ret;
 233 }
 234
 235 static int
 236 nfnl_acct_del(struct sock *nfnl, struct sk_buff *skb,
 237              const struct nlmsghdr *nlh, const struct nlattr * const tb[])
 238 {
 239         char *acct_name;
 240         struct nf_acct *cur;
 241         int ret = -ENOENT;
 242
 243         if (!tb[NFACCT_NAME]) {
 244                 list_for_each_entry(cur, &nfnl_acct_list, head)
 245                         nfnl_acct_try_del(cur);
 246
 247                 return 0;
 248         }
 249         acct_name = nla_data(tb[NFACCT_NAME]);
 250
 251         list_for_each_entry(cur, &nfnl_acct_list, head) {
 252                 if (strncmp(cur->name, acct_name, NFACCT_NAME_MAX) != 0)
 253                         continue;
 254
 255                 ret = nfnl_acct_try_del(cur);
 256                 if (ret < 0)
 257                         return ret;
 258
 259                 break;
 260         }
 261         return ret;
 262 }
 263
 264 static const struct nla_policy nfnl_acct_policy[NFACCT_MAX+1] = {
 265         [NFACCT_NAME] = { .type = NLA_NUL_STRING, .len = NFACCT_NAME_MAX-1 },
 266         [NFACCT_BYTES] = { .type = NLA_U64 },
 267         [NFACCT_PKTS] = { .type = NLA_U64 },
 268 };
 269
 270 static const struct nfnl_callback nfnl_acct_cb[NFNL_MSG_ACCT_MAX] = {
 271         [NFNL_MSG_ACCT_NEW]             = { .call = nfnl_acct_new,
 272                                             .attr_count = NFACCT_MAX,
 273                                             .policy = nfnl_acct_policy },
 274         [NFNL_MSG_ACCT_GET]             = { .call = nfnl_acct_get,
 275                                             .attr_count = NFACCT_MAX,
 276                                             .policy = nfnl_acct_policy },
 277         [NFNL_MSG_ACCT_GET_CTRZERO]     = { .call = nfnl_acct_get,
 278                                             .attr_count = NFACCT_MAX,
 279                                             .policy = nfnl_acct_policy },
 280         [NFNL_MSG_ACCT_DEL]             = { .call = nfnl_acct_del,
 281                                             .attr_count = NFACCT_MAX,
 282                                             .policy = nfnl_acct_policy },
 283 };
 284
 285 static const struct nfnetlink_subsystem nfnl_acct_subsys = {
 286         .name                           = "acct",
 287         .subsys_id                      = NFNL_SUBSYS_ACCT,
 288         .cb_count                       = NFNL_MSG_ACCT_MAX,
 289         .cb                             = nfnl_acct_cb,
 290 };
 291
 292 MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_ACCT);
 293
 294 struct nf_acct *nfnl_acct_find_get(const char *acct_name)
 295 {
 296         struct nf_acct *cur, *acct = NULL;
 297
 298         rcu_read_lock();
 299         list_for_each_entry_rcu(cur, &nfnl_acct_list, head) {
 300                 if (strncmp(cur->name, acct_name, NFACCT_NAME_MAX)!= 0)
 301                         continue;
 302
 303                 if (!try_module_get(THIS_MODULE))
 304                         goto err;
 305
 306                 if (!atomic_inc_not_zero(&cur->refcnt)) {
 307                         module_put(THIS_MODULE);
 308                         goto err;
 309                 }
 310
 311                 acct = cur;
 312                 break;
 313         }
 314 err:
 315         rcu_read_unlock();
 316         return acct;
 317 }
 318 EXPORT_SYMBOL_GPL(nfnl_acct_find_get);
 319
 320 void nfnl_acct_put(struct nf_acct *acct)
 321 {
 322         atomic_dec(&acct->refcnt);
 323         module_put(THIS_MODULE);
 324 }
 325 EXPORT_SYMBOL_GPL(nfnl_acct_put);
 326
 327 void nfnl_acct_update(const struct sk_buff *skb, struct nf_acct *nfacct)
 328 {
 329         atomic64_inc(&nfacct->pkts);
 330         atomic64_add(skb->len, &nfacct->bytes);
 331 }
 332 EXPORT_SYMBOL_GPL(nfnl_acct_update);
 333
 334 static int __init nfnl_acct_init(void)
 335 {
 336         int ret;
 337
 338         pr_info("nfnl_acct: registering with nfnetlink.\n");
 339         ret = nfnetlink_subsys_register(&nfnl_acct_subsys);
 340         if (ret < 0) {
 341                 pr_err("nfnl_acct_init: cannot register with nfnetlink.\n");
 342                 goto err_out;
 343         }
 344         return 0;
 345 err_out:
 346         return ret;
 347 }
 348
 349 static void __exit nfnl_acct_exit(void)
 350 {
 351         struct nf_acct *cur, *tmp;
 352
 353         pr_info("nfnl_acct: unregistering from nfnetlink.\n");
 354         nfnetlink_subsys_unregister(&nfnl_acct_subsys);
 355
 356         list_for_each_entry_safe(cur, tmp, &nfnl_acct_list, head) {
 357                 list_del_rcu(&cur->head);
 358                 /* We are sure that our objects have no clients at this point,
 359                  * it's safe to release them all without checking refcnt. */
 360                 kfree_rcu(cur, rcu_head);
 361         }
 362 }
 363
 364 module_init(nfnl_acct_init);
 365 module_exit(nfnl_acct_exit);