| /* |
| * netfilter module to enforce network quotas |
| * |
| * Sam Johnston <samj@samj.net> |
| */ |
| #include <linux/skbuff.h> |
| #include <linux/spinlock.h> |
| |
| #include <linux/netfilter/x_tables.h> |
| #include <linux/netfilter/xt_quota.h> |
| |
| struct xt_quota_priv { |
| uint64_t quota; |
| }; |
| |
| MODULE_LICENSE("GPL"); |
| MODULE_AUTHOR("Sam Johnston <samj@samj.net>"); |
| MODULE_DESCRIPTION("Xtables: countdown quota match"); |
| MODULE_ALIAS("ipt_quota"); |
| MODULE_ALIAS("ip6t_quota"); |
| |
| static DEFINE_SPINLOCK(quota_lock); |
| |
| static bool |
| quota_mt(const struct sk_buff *skb, const struct xt_match_param *par) |
| { |
| struct xt_quota_info *q = (void *)par->matchinfo; |
| struct xt_quota_priv *priv = q->master; |
| bool ret = q->flags & XT_QUOTA_INVERT; |
| |
| spin_lock_bh("a_lock); |
| if (priv->quota >= skb->len) { |
| priv->quota -= skb->len; |
| ret = !ret; |
| } else { |
| /* we do not allow even small packets from now on */ |
| priv->quota = 0; |
| } |
| /* Copy quota back to matchinfo so that iptables can display it */ |
| q->quota = priv->quota; |
| spin_unlock_bh("a_lock); |
| |
| return ret; |
| } |
| |
| static int quota_mt_check(const struct xt_mtchk_param *par) |
| { |
| struct xt_quota_info *q = par->matchinfo; |
| |
| if (q->flags & ~XT_QUOTA_MASK) |
| return -EINVAL; |
| |
| q->master = kmalloc(sizeof(*q->master), GFP_KERNEL); |
| if (q->master == NULL) |
| return -EINVAL; |
| |
| q->master->quota = q->quota; |
| return 0; |
| } |
| |
| static void quota_mt_destroy(const struct xt_mtdtor_param *par) |
| { |
| const struct xt_quota_info *q = par->matchinfo; |
| |
| kfree(q->master); |
| } |
| |
| static struct xt_match quota_mt_reg __read_mostly = { |
| .name = "quota", |
| .revision = 0, |
| .family = NFPROTO_UNSPEC, |
| .match = quota_mt, |
| .checkentry = quota_mt_check, |
| .destroy = quota_mt_destroy, |
| .matchsize = sizeof(struct xt_quota_info), |
| .me = THIS_MODULE, |
| }; |
| |
| static int __init quota_mt_init(void) |
| { |
| return xt_register_match("a_mt_reg); |
| } |
| |
| static void __exit quota_mt_exit(void) |
| { |
| xt_unregister_match("a_mt_reg); |
| } |
| |
| module_init(quota_mt_init); |
| module_exit(quota_mt_exit); |