Add the rt linux 4.1.3-rt3 as base

[kvmfornfv.git] / kernel / net / bridge / netfilter / ebt_limit.c

diff --git a/kernel/net/bridge/netfilter/ebt_limit.c b/kernel/net/bridge/netfilter/ebt_limit.c
new file mode 100644 (file)
index 0000000..517e78b
--- /dev/null
+++ b/kernel/net/bridge/netfilter/ebt_limit.c
@@ -0,0 +1,127 @@
+/*
+ *  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
+ *
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+#include <linux/module.h>
+#include <linux/netdevice.h>
+#include <linux/spinlock.h>
+#include <linux/netfilter/x_tables.h>
+#include <linux/netfilter_bridge/ebtables.h>
+#include <linux/netfilter_bridge/ebt_limit.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 bool
+ebt_limit_mt(const struct sk_buff *skb, struct xt_action_param *par)
+{
+       struct ebt_limit_info *info = (void *)par->matchinfo;
+       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 true;
+       }
+
+       spin_unlock_bh(&limit_lock);
+       return false;
+}
+
+/* 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_mt_check(const struct xt_mtchk_param *par)
+{
+       struct ebt_limit_info *info = par->matchinfo;
+
+       /* Check for overflow. */
+       if (info->burst == 0 ||
+           user2credits(info->avg * info->burst) < user2credits(info->avg)) {
+               pr_info("overflow, 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;
+}
+
+
+#ifdef CONFIG_COMPAT
+/*
+ * no conversion function needed --
+ * only avg/burst have meaningful values in userspace.
+ */
+struct ebt_compat_limit_info {
+       compat_uint_t avg, burst;
+       compat_ulong_t prev;
+       compat_uint_t credit, credit_cap, cost;
+};
+#endif
+
+static struct xt_match ebt_limit_mt_reg __read_mostly = {
+       .name           = "limit",
+       .revision       = 0,
+       .family         = NFPROTO_BRIDGE,
+       .match          = ebt_limit_mt,
+       .checkentry     = ebt_limit_mt_check,
+       .matchsize      = sizeof(struct ebt_limit_info),
+#ifdef CONFIG_COMPAT
+       .compatsize     = sizeof(struct ebt_compat_limit_info),
+#endif
+       .me             = THIS_MODULE,
+};
+
+static int __init ebt_limit_init(void)
+{
+       return xt_register_match(&ebt_limit_mt_reg);
+}
+
+static void __exit ebt_limit_fini(void)
+{
+       xt_unregister_match(&ebt_limit_mt_reg);
+}
+
+module_init(ebt_limit_init);
+module_exit(ebt_limit_fini);
+MODULE_DESCRIPTION("Ebtables: Rate-limit match");
+MODULE_LICENSE("GPL");