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/netlink.h>
  14 #include <linux/rculist.h>
  15 #include <linux/slab.h>
  16 #include <linux/types.h>
  17 #include <linux/errno.h>
  18 #include <net/netlink.h>
  19 #include <net/sock.h>
  20 #include <asm/atomic.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         NLA_PUT_STRING(skb, NFACCT_NAME, acct->name);
 113
 114         if (type == NFNL_MSG_ACCT_GET_CTRZERO) {
 115                 pkts = atomic64_xchg(&acct->pkts, 0);
 116                 bytes = atomic64_xchg(&acct->bytes, 0);
 117         } else {
 118                 pkts = atomic64_read(&acct->pkts);
 119                 bytes = atomic64_read(&acct->bytes);
 120         }
 121         NLA_PUT_BE64(skb, NFACCT_PKTS, cpu_to_be64(pkts));
 122         NLA_PUT_BE64(skb, NFACCT_BYTES, cpu_to_be64(bytes));
 123         NLA_PUT_BE32(skb, NFACCT_USE, htonl(atomic_read(&acct->refcnt)));
 124
 125         nlmsg_end(skb, nlh);
 126         return skb->len;
 127
 128 nlmsg_failure:
 129 nla_put_failure:
 130         nlmsg_cancel(skb, nlh);
 131         return -1;
 132 }
 133
 134 static int
 135 nfnl_acct_dump(struct sk_buff *skb, struct netlink_callback *cb)
 136 {
 137         struct nf_acct *cur, *last;
 138
 139         if (cb->args[2])
 140                 return 0;
 141
 142         last = (struct nf_acct *)cb->args[1];
 143         if (cb->args[1])
 144                 cb->args[1] = 0;
 145
 146         rcu_read_lock();
 147         list_for_each_entry_rcu(cur, &nfnl_acct_list, head) {
 148                 if (last && cur != last)
 149                         continue;
 150
 151                 if (nfnl_acct_fill_info(skb, NETLINK_CB(cb->skb).pid,
 152                                        cb->nlh->nlmsg_seq,
 153                                        NFNL_MSG_TYPE(cb->nlh->nlmsg_type),
 154                                        NFNL_MSG_ACCT_NEW, cur) < 0) {
 155                         cb->args[1] = (unsigned long)cur;
 156                         break;
 157                 }
 158         }
 159         if (!cb->args[1])
 160                 cb->args[2] = 1;
 161         rcu_read_unlock();
 162         return skb->len;
 163 }
 164
 165 static int
 166 nfnl_acct_get(struct sock *nfnl, struct sk_buff *skb,
 167              const struct nlmsghdr *nlh, const struct nlattr * const tb[])
 168 {
 169         int ret = -ENOENT;
 170         struct nf_acct *cur;
 171         char *acct_name;
 172
 173         if (nlh->nlmsg_flags & NLM_F_DUMP) {
 174                 return netlink_dump_start(nfnl, skb, nlh, nfnl_acct_dump,
 175                                           NULL, 0);
 176         }
 177
 178         if (!tb[NFACCT_NAME])
 179                 return -EINVAL;
 180         acct_name = nla_data(tb[NFACCT_NAME]);
 181
 182         list_for_each_entry(cur, &nfnl_acct_list, head) {
 183                 struct sk_buff *skb2;
 184
 185                 if (strncmp(cur->name, acct_name, NFACCT_NAME_MAX)!= 0)
 186                         continue;
 187
 188                 skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 189                 if (skb2 == NULL) {
 190                         ret = -ENOMEM;
 191                         break;
 192                 }
 193
 194                 ret = nfnl_acct_fill_info(skb2, NETLINK_CB(skb).pid,
 195                                          nlh->nlmsg_seq,
 196                                          NFNL_MSG_TYPE(nlh->nlmsg_type),
 197                                          NFNL_MSG_ACCT_NEW, cur);
 198                 if (ret <= 0) {
 199                         kfree_skb(skb2);
 200                         break;
 201                 }
 202                 ret = netlink_unicast(nfnl, skb2, NETLINK_CB(skb).pid,
 203                                         MSG_DONTWAIT);
 204                 if (ret > 0)
 205                         ret = 0;
 206
 207                 /* this avoids a loop in nfnetlink. */
 208                 return ret == -EAGAIN ? -ENOBUFS : ret;
 209         }
 210         return ret;
 211 }
 212
 213 /* try to delete object, fail if it is still in use. */
 214 static int nfnl_acct_try_del(struct nf_acct *cur)
 215 {
 216         int ret = 0;
 217
 218         /* we want to avoid races with nfnl_acct_find_get. */
 219         if (atomic_dec_and_test(&cur->refcnt)) {
 220                 /* We are protected by nfnl mutex. */
 221                 list_del_rcu(&cur->head);
 222                 kfree_rcu(cur, rcu_head);
 223         } else {
 224                 /* still in use, restore reference counter. */
 225                 atomic_inc(&cur->refcnt);
 226                 ret = -EBUSY;
 227         }
 228         return ret;
 229 }
 230
 231 static int
 232 nfnl_acct_del(struct sock *nfnl, struct sk_buff *skb,
 233              const struct nlmsghdr *nlh, const struct nlattr * const tb[])
 234 {
 235         char *acct_name;
 236         struct nf_acct *cur;
 237         int ret = -ENOENT;
 238
 239         if (!tb[NFACCT_NAME]) {
 240                 list_for_each_entry(cur, &nfnl_acct_list, head)
 241                         nfnl_acct_try_del(cur);
 242
 243                 return 0;
 244         }
 245         acct_name = nla_data(tb[NFACCT_NAME]);
 246
 247         list_for_each_entry(cur, &nfnl_acct_list, head) {
 248                 if (strncmp(cur->name, acct_name, NFACCT_NAME_MAX) != 0)
 249                         continue;
 250
 251                 ret = nfnl_acct_try_del(cur);
 252                 if (ret < 0)
 253                         return ret;
 254
 255                 break;
 256         }
 257         return ret;
 258 }
 259
 260 static const struct nla_policy nfnl_acct_policy[NFACCT_MAX+1] = {
 261         [NFACCT_NAME] = { .type = NLA_NUL_STRING, .len = NFACCT_NAME_MAX-1 },
 262         [NFACCT_BYTES] = { .type = NLA_U64 },
 263         [NFACCT_PKTS] = { .type = NLA_U64 },
 264 };
 265
 266 static const struct nfnl_callback nfnl_acct_cb[NFNL_MSG_ACCT_MAX] = {
 267         [NFNL_MSG_ACCT_NEW]             = { .call = nfnl_acct_new,
 268                                             .attr_count = NFACCT_MAX,
 269                                             .policy = nfnl_acct_policy },
 270         [NFNL_MSG_ACCT_GET]             = { .call = nfnl_acct_get,
 271                                             .attr_count = NFACCT_MAX,
 272                                             .policy = nfnl_acct_policy },
 273         [NFNL_MSG_ACCT_GET_CTRZERO]     = { .call = nfnl_acct_get,
 274                                             .attr_count = NFACCT_MAX,
 275                                             .policy = nfnl_acct_policy },
 276         [NFNL_MSG_ACCT_DEL]             = { .call = nfnl_acct_del,
 277                                             .attr_count = NFACCT_MAX,
 278                                             .policy = nfnl_acct_policy },
 279 };
 280
 281 static const struct nfnetlink_subsystem nfnl_acct_subsys = {
 282         .name                           = "acct",
 283         .subsys_id                      = NFNL_SUBSYS_ACCT,
 284         .cb_count                       = NFNL_MSG_ACCT_MAX,
 285         .cb                             = nfnl_acct_cb,
 286 };
 287
 288 MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_ACCT);
 289
 290 struct nf_acct *nfnl_acct_find_get(const char *acct_name)
 291 {
 292         struct nf_acct *cur, *acct = NULL;
 293
 294         rcu_read_lock();
 295         list_for_each_entry_rcu(cur, &nfnl_acct_list, head) {
 296                 if (strncmp(cur->name, acct_name, NFACCT_NAME_MAX)!= 0)
 297                         continue;
 298
 299                 if (!try_module_get(THIS_MODULE))
 300                         goto err;
 301
 302                 if (!atomic_inc_not_zero(&cur->refcnt)) {
 303                         module_put(THIS_MODULE);
 304                         goto err;
 305                 }
 306
 307                 acct = cur;
 308                 break;
 309         }
 310 err:
 311         rcu_read_unlock();
 312         return acct;
 313 }
 314 EXPORT_SYMBOL_GPL(nfnl_acct_find_get);
 315
 316 void nfnl_acct_put(struct nf_acct *acct)
 317 {
 318         atomic_dec(&acct->refcnt);
 319         module_put(THIS_MODULE);
 320 }
 321 EXPORT_SYMBOL_GPL(nfnl_acct_put);
 322
 323 void nfnl_acct_update(const struct sk_buff *skb, struct nf_acct *nfacct)
 324 {
 325         atomic64_inc(&nfacct->pkts);
 326         atomic64_add(skb->len, &nfacct->bytes);
 327 }
 328 EXPORT_SYMBOL_GPL(nfnl_acct_update);
 329
 330 static int __init nfnl_acct_init(void)
 331 {
 332         int ret;
 333
 334         pr_info("nfnl_acct: registering with nfnetlink.\n");
 335         ret = nfnetlink_subsys_register(&nfnl_acct_subsys);
 336         if (ret < 0) {
 337                 pr_err("nfnl_acct_init: cannot register with nfnetlink.\n");
 338                 goto err_out;
 339         }
 340         return 0;
 341 err_out:
 342         return ret;
 343 }
 344
 345 static void __exit nfnl_acct_exit(void)
 346 {
 347         struct nf_acct *cur, *tmp;
 348
 349         pr_info("nfnl_acct: unregistering from nfnetlink.\n");
 350         nfnetlink_subsys_unregister(&nfnl_acct_subsys);
 351
 352         list_for_each_entry_safe(cur, tmp, &nfnl_acct_list, head) {
 353                 list_del_rcu(&cur->head);
 354                 /* We are sure that our objects have no clients at this point,
 355                  * it's safe to release them all without checking refcnt. */
 356                 kfree_rcu(cur, rcu_head);
 357         }
 358 }
 359
 360 module_init(nfnl_acct_init);
 361 module_exit(nfnl_acct_exit);