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![Jan Engelhardt](/assets/img/avatar_default.png)
When a match or target is looked up using xt_find_{match,target}, Xtables will also search the NFPROTO_UNSPEC module list. This allows for protocol-independent extensions (like xt_time) to be reused from other components (e.g. arptables, ebtables). Extensions that take different codepaths depending on match->family or target->family of course cannot use NFPROTO_UNSPEC within the registration structure (e.g. xt_pkttype). Signed-off-by: Jan Engelhardt <jengelh@medozas.de> Signed-off-by: Patrick McHardy <kaber@trash.net>
78 lines
1.8 KiB
C
78 lines
1.8 KiB
C
/*
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* netfilter module to enforce network quotas
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*
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* Sam Johnston <samj@samj.net>
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*/
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#include <linux/skbuff.h>
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#include <linux/spinlock.h>
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#include <linux/netfilter/x_tables.h>
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#include <linux/netfilter/xt_quota.h>
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Sam Johnston <samj@samj.net>");
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MODULE_DESCRIPTION("Xtables: countdown quota match");
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MODULE_ALIAS("ipt_quota");
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MODULE_ALIAS("ip6t_quota");
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static DEFINE_SPINLOCK(quota_lock);
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static bool
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quota_mt(const struct sk_buff *skb, const struct net_device *in,
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const struct net_device *out, const struct xt_match *match,
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const void *matchinfo, int offset, unsigned int protoff,
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bool *hotdrop)
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{
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struct xt_quota_info *q =
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((const struct xt_quota_info *)matchinfo)->master;
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bool ret = q->flags & XT_QUOTA_INVERT;
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spin_lock_bh("a_lock);
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if (q->quota >= skb->len) {
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q->quota -= skb->len;
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ret = !ret;
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} else {
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/* we do not allow even small packets from now on */
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q->quota = 0;
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}
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spin_unlock_bh("a_lock);
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return ret;
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}
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static bool
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quota_mt_check(const char *tablename, const void *entry,
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const struct xt_match *match, void *matchinfo,
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unsigned int hook_mask)
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{
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struct xt_quota_info *q = matchinfo;
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if (q->flags & ~XT_QUOTA_MASK)
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return false;
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/* For SMP, we only want to use one set of counters. */
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q->master = q;
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return true;
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}
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static struct xt_match quota_mt_reg __read_mostly = {
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.name = "quota",
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.revision = 0,
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.family = NFPROTO_UNSPEC,
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.match = quota_mt,
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.checkentry = quota_mt_check,
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.matchsize = sizeof(struct xt_quota_info),
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.me = THIS_MODULE,
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};
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static int __init quota_mt_init(void)
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{
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return xt_register_match("a_mt_reg);
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}
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static void __exit quota_mt_exit(void)
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{
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xt_unregister_match("a_mt_reg);
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}
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module_init(quota_mt_init);
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module_exit(quota_mt_exit);
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