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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /net/bridge/netfilter/ebt_limit.c
Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
Diffstat (limited to 'net/bridge/netfilter/ebt_limit.c')
-rw-r--r--net/bridge/netfilter/ebt_limit.c113
1 files changed, 113 insertions, 0 deletions
diff --git a/net/bridge/netfilter/ebt_limit.c b/net/bridge/netfilter/ebt_limit.c
new file mode 100644
index 00000000000..637c8844cd5
--- /dev/null
+++ b/net/bridge/netfilter/ebt_limit.c
@@ -0,0 +1,113 @@
+/*
+ * ebt_limit
+ *
+ * Authors:
+ * Tom Marshall <tommy@home.tig-grr.com>
+ *
+ * Mostly copied from netfilter's ipt_limit.c, see that file for
+ * more explanation
+ *
+ * September, 2003
+ *
+ */
+
+#include <linux/netfilter_bridge/ebtables.h>
+#include <linux/netfilter_bridge/ebt_limit.h>
+#include <linux/module.h>
+
+#include <linux/netdevice.h>
+#include <linux/spinlock.h>
+
+static DEFINE_SPINLOCK(limit_lock);
+
+#define MAX_CPJ (0xFFFFFFFF / (HZ*60*60*24))
+
+#define _POW2_BELOW2(x) ((x)|((x)>>1))
+#define _POW2_BELOW4(x) (_POW2_BELOW2(x)|_POW2_BELOW2((x)>>2))
+#define _POW2_BELOW8(x) (_POW2_BELOW4(x)|_POW2_BELOW4((x)>>4))
+#define _POW2_BELOW16(x) (_POW2_BELOW8(x)|_POW2_BELOW8((x)>>8))
+#define _POW2_BELOW32(x) (_POW2_BELOW16(x)|_POW2_BELOW16((x)>>16))
+#define POW2_BELOW32(x) ((_POW2_BELOW32(x)>>1) + 1)
+
+#define CREDITS_PER_JIFFY POW2_BELOW32(MAX_CPJ)
+
+static int ebt_limit_match(const struct sk_buff *skb,
+ const struct net_device *in, const struct net_device *out,
+ const void *data, unsigned int datalen)
+{
+ struct ebt_limit_info *info = (struct ebt_limit_info *)data;
+ unsigned long now = jiffies;
+
+ spin_lock_bh(&limit_lock);
+ info->credit += (now - xchg(&info->prev, now)) * CREDITS_PER_JIFFY;
+ if (info->credit > info->credit_cap)
+ info->credit = info->credit_cap;
+
+ if (info->credit >= info->cost) {
+ /* We're not limited. */
+ info->credit -= info->cost;
+ spin_unlock_bh(&limit_lock);
+ return EBT_MATCH;
+ }
+
+ spin_unlock_bh(&limit_lock);
+ return EBT_NOMATCH;
+}
+
+/* Precision saver. */
+static u_int32_t
+user2credits(u_int32_t user)
+{
+ /* If multiplying would overflow... */
+ if (user > 0xFFFFFFFF / (HZ*CREDITS_PER_JIFFY))
+ /* Divide first. */
+ return (user / EBT_LIMIT_SCALE) * HZ * CREDITS_PER_JIFFY;
+
+ return (user * HZ * CREDITS_PER_JIFFY) / EBT_LIMIT_SCALE;
+}
+
+static int ebt_limit_check(const char *tablename, unsigned int hookmask,
+ const struct ebt_entry *e, void *data, unsigned int datalen)
+{
+ struct ebt_limit_info *info = (struct ebt_limit_info *)data;
+
+ if (datalen != EBT_ALIGN(sizeof(struct ebt_limit_info)))
+ return -EINVAL;
+
+ /* Check for overflow. */
+ if (info->burst == 0 ||
+ user2credits(info->avg * info->burst) < user2credits(info->avg)) {
+ printk("Overflow in ebt_limit, try lower: %u/%u\n",
+ info->avg, info->burst);
+ return -EINVAL;
+ }
+
+ /* User avg in seconds * EBT_LIMIT_SCALE: convert to jiffies * 128. */
+ info->prev = jiffies;
+ info->credit = user2credits(info->avg * info->burst);
+ info->credit_cap = user2credits(info->avg * info->burst);
+ info->cost = user2credits(info->avg);
+ return 0;
+}
+
+static struct ebt_match ebt_limit_reg =
+{
+ .name = EBT_LIMIT_MATCH,
+ .match = ebt_limit_match,
+ .check = ebt_limit_check,
+ .me = THIS_MODULE,
+};
+
+static int __init init(void)
+{
+ return ebt_register_match(&ebt_limit_reg);
+}
+
+static void __exit fini(void)
+{
+ ebt_unregister_match(&ebt_limit_reg);
+}
+
+module_init(init);
+module_exit(fini);
+MODULE_LICENSE("GPL");