[PATCH 08/15] netfilter: nft_limit: add burst parameter

[Pablo Neira Ayuso]

This patch adds the burst parameter. This burst indicates the number of packets
that can exceed the limit.

Signed-off-by: Pablo Neira Ayuso <pa...@netfilter.org>
---
 include/uapi/linux/netfilter/nf_tables.h |    2 ++
 net/netfilter/nft_limit.c                |   20 ++++++++++++++++++--
 2 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/include/uapi/linux/netfilter/nf_tables.h 
b/include/uapi/linux/netfilter/nf_tables.h
index 2ef35f2..cafd789 100644
--- a/include/uapi/linux/netfilter/nf_tables.h
+++ b/include/uapi/linux/netfilter/nf_tables.h
@@ -761,11 +761,13 @@ enum nft_ct_attributes {
  *
  * @NFTA_LIMIT_RATE: refill rate (NLA_U64)
  * @NFTA_LIMIT_UNIT: refill unit (NLA_U64)
+ * @NFTA_LIMIT_BURST: burst (NLA_U32)
  */
 enum nft_limit_attributes {
        NFTA_LIMIT_UNSPEC,
        NFTA_LIMIT_RATE,
        NFTA_LIMIT_UNIT,
+       NFTA_LIMIT_BURST,
        __NFTA_LIMIT_MAX
 };
 #define NFTA_LIMIT_MAX         (__NFTA_LIMIT_MAX - 1)
diff --git a/net/netfilter/nft_limit.c b/net/netfilter/nft_limit.c
index c4d1b1b..d8c5ff1 100644
--- a/net/netfilter/nft_limit.c
+++ b/net/netfilter/nft_limit.c
@@ -25,6 +25,7 @@ struct nft_limit {
        u64             tokens_max;
        u64             rate;
        u64             nsecs;
+       u32             burst;
 };
 
 static inline bool nft_limit_eval(struct nft_limit *limit, u64 cost)
@@ -65,6 +66,18 @@ static int nft_limit_init(struct nft_limit *limit,
        if (limit->rate == 0 || limit->nsecs < unit)
                return -EOVERFLOW;
        limit->tokens = limit->tokens_max = limit->nsecs;
+
+       if (tb[NFTA_LIMIT_BURST]) {
+               u64 rate;
+
+               limit->burst = ntohl(nla_get_be32(tb[NFTA_LIMIT_BURST]));
+
+               rate = limit->rate + limit->burst;
+               if (rate < limit->rate)
+                       return -EOVERFLOW;
+
+               limit->rate = rate;
+       }
        limit->last = ktime_get_ns();
 
        return 0;
@@ -73,9 +86,11 @@ static int nft_limit_init(struct nft_limit *limit,
 static int nft_limit_dump(struct sk_buff *skb, const struct nft_limit *limit)
 {
        u64 secs = div_u64(limit->nsecs, NSEC_PER_SEC);
+       u64 rate = limit->rate - limit->burst;
 
-       if (nla_put_be64(skb, NFTA_LIMIT_RATE, cpu_to_be64(limit->rate)) ||
-           nla_put_be64(skb, NFTA_LIMIT_UNIT, cpu_to_be64(secs)))
+       if (nla_put_be64(skb, NFTA_LIMIT_RATE, cpu_to_be64(rate)) ||
+           nla_put_be64(skb, NFTA_LIMIT_UNIT, cpu_to_be64(secs)) ||
+           nla_put_be32(skb, NFTA_LIMIT_BURST, htonl(limit->burst)))
                goto nla_put_failure;
        return 0;
 
@@ -96,6 +111,7 @@ static void nft_limit_pkts_eval(const struct nft_expr *expr,
 static const struct nla_policy nft_limit_policy[NFTA_LIMIT_MAX + 1] = {
        [NFTA_LIMIT_RATE]       = { .type = NLA_U64 },
        [NFTA_LIMIT_UNIT]       = { .type = NLA_U64 },
+       [NFTA_LIMIT_BURST]      = { .type = NLA_U32 },
 };
 
 static int nft_limit_pkts_init(const struct nft_ctx *ctx,
-- 
1.7.10.4

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