From 0197dee7d3182bb6b6a21955860dfa14fa022d84 Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Mon, 7 May 2012 10:51:45 +0000 Subject: [PATCH] netfilter: hashlimit: byte-based limit mode can be used e.g. for ingress traffic policing or to detect when a host/port consumes more bandwidth than expected. This is done by optionally making cost to mean "cost per 16-byte-chunk-of-data" instead of "cost per packet". Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso --- include/linux/netfilter/xt_hashlimit.h | 10 ++- net/netfilter/xt_hashlimit.c | 116 +++++++++++++++++++++++++++------ 2 files changed, 106 insertions(+), 20 deletions(-) diff --git a/include/linux/netfilter/xt_hashlimit.h b/include/linux/netfilter/xt_hashlimit.h index b1925b5..05fe799 100644 --- a/include/linux/netfilter/xt_hashlimit.h +++ b/include/linux/netfilter/xt_hashlimit.h @@ -6,7 +6,11 @@ /* timings are in milliseconds. */ #define XT_HASHLIMIT_SCALE 10000 /* 1/10,000 sec period => max of 10,000/sec. Min rate is then 429490 - seconds, or one every 59 hours. */ + * seconds, or one packet every 59 hours. + */ + +/* packet length accounting is done in 16-byte steps */ +#define XT_HASHLIMIT_BYTE_SHIFT 4 /* details of this structure hidden by the implementation */ struct xt_hashlimit_htable; @@ -17,6 +21,10 @@ enum { XT_HASHLIMIT_HASH_SIP = 1 << 2, XT_HASHLIMIT_HASH_SPT = 1 << 3, XT_HASHLIMIT_INVERT = 1 << 4, + XT_HASHLIMIT_BYTES = 1 << 5, +#ifdef __KERNEL__ + XT_HASHLIMIT_MAX = 1 << 6, +#endif }; struct hashlimit_cfg { diff --git a/net/netfilter/xt_hashlimit.c b/net/netfilter/xt_hashlimit.c index b6bbd06..d0424f9 100644 --- a/net/netfilter/xt_hashlimit.c +++ b/net/netfilter/xt_hashlimit.c @@ -388,6 +388,18 @@ static void htable_put(struct xt_hashlimit_htable *hinfo) #define CREDITS_PER_JIFFY POW2_BELOW32(MAX_CPJ) +/* in byte mode, the lowest possible rate is one packet/second. + * credit_cap is used as a counter that tells us how many times we can + * refill the "credits available" counter when it becomes empty. + */ +#define MAX_CPJ_BYTES (0xFFFFFFFF / HZ) +#define CREDITS_PER_JIFFY_BYTES POW2_BELOW32(MAX_CPJ_BYTES) + +static u32 xt_hashlimit_len_to_chunks(u32 len) +{ + return (len >> XT_HASHLIMIT_BYTE_SHIFT) + 1; +} + /* Precision saver. */ static u32 user2credits(u32 user) { @@ -399,21 +411,53 @@ static u32 user2credits(u32 user) return (user * HZ * CREDITS_PER_JIFFY) / XT_HASHLIMIT_SCALE; } -static void rateinfo_recalc(struct dsthash_ent *dh, unsigned long now) +static u32 user2credits_byte(u32 user) { - dh->rateinfo.credit += (now - dh->rateinfo.prev) * CREDITS_PER_JIFFY; - if (dh->rateinfo.credit > dh->rateinfo.credit_cap) - dh->rateinfo.credit = dh->rateinfo.credit_cap; + u64 us = user; + us *= HZ * CREDITS_PER_JIFFY_BYTES; + return (u32) (us >> 32); +} + +static void rateinfo_recalc(struct dsthash_ent *dh, unsigned long now, u32 mode) +{ + unsigned long delta = now - dh->rateinfo.prev; + u32 cap; + + if (delta == 0) + return; + dh->rateinfo.prev = now; + + if (mode & XT_HASHLIMIT_BYTES) { + u32 tmp = dh->rateinfo.credit; + dh->rateinfo.credit += CREDITS_PER_JIFFY_BYTES * delta; + cap = CREDITS_PER_JIFFY_BYTES * HZ; + if (tmp >= dh->rateinfo.credit) {/* overflow */ + dh->rateinfo.credit = cap; + return; + } + } else { + dh->rateinfo.credit += delta * CREDITS_PER_JIFFY; + cap = dh->rateinfo.credit_cap; + } + if (dh->rateinfo.credit > cap) + dh->rateinfo.credit = cap; } static void rateinfo_init(struct dsthash_ent *dh, struct xt_hashlimit_htable *hinfo) { dh->rateinfo.prev = jiffies; - dh->rateinfo.credit = user2credits(hinfo->cfg.avg * hinfo->cfg.burst); - dh->rateinfo.cost = user2credits(hinfo->cfg.avg); - dh->rateinfo.credit_cap = dh->rateinfo.credit; + if (hinfo->cfg.mode & XT_HASHLIMIT_BYTES) { + dh->rateinfo.credit = CREDITS_PER_JIFFY_BYTES * HZ; + dh->rateinfo.cost = user2credits_byte(hinfo->cfg.avg); + dh->rateinfo.credit_cap = hinfo->cfg.burst; + } else { + dh->rateinfo.credit = user2credits(hinfo->cfg.avg * + hinfo->cfg.burst); + dh->rateinfo.cost = user2credits(hinfo->cfg.avg); + dh->rateinfo.credit_cap = dh->rateinfo.credit; + } } static inline __be32 maskl(__be32 a, unsigned int l) @@ -519,6 +563,21 @@ hashlimit_init_dst(const struct xt_hashlimit_htable *hinfo, return 0; } +static u32 hashlimit_byte_cost(unsigned int len, struct dsthash_ent *dh) +{ + u64 tmp = xt_hashlimit_len_to_chunks(len); + tmp = tmp * dh->rateinfo.cost; + + if (unlikely(tmp > CREDITS_PER_JIFFY_BYTES * HZ)) + tmp = CREDITS_PER_JIFFY_BYTES * HZ; + + if (dh->rateinfo.credit < tmp && dh->rateinfo.credit_cap) { + dh->rateinfo.credit_cap--; + dh->rateinfo.credit = CREDITS_PER_JIFFY_BYTES * HZ; + } + return (u32) tmp; +} + static bool hashlimit_mt(const struct sk_buff *skb, struct xt_action_param *par) { @@ -527,6 +586,7 @@ hashlimit_mt(const struct sk_buff *skb, struct xt_action_param *par) unsigned long now = jiffies; struct dsthash_ent *dh; struct dsthash_dst dst; + u32 cost; if (hashlimit_init_dst(hinfo, &dst, skb, par->thoff) < 0) goto hotdrop; @@ -544,12 +604,17 @@ hashlimit_mt(const struct sk_buff *skb, struct xt_action_param *par) } else { /* update expiration timeout */ dh->expires = now + msecs_to_jiffies(hinfo->cfg.expire); - rateinfo_recalc(dh, now); + rateinfo_recalc(dh, now, hinfo->cfg.mode); } - if (dh->rateinfo.credit >= dh->rateinfo.cost) { + if (info->cfg.mode & XT_HASHLIMIT_BYTES) + cost = hashlimit_byte_cost(skb->len, dh); + else + cost = dh->rateinfo.cost; + + if (dh->rateinfo.credit >= cost) { /* below the limit */ - dh->rateinfo.credit -= dh->rateinfo.cost; + dh->rateinfo.credit -= cost; spin_unlock(&dh->lock); rcu_read_unlock_bh(); return !(info->cfg.mode & XT_HASHLIMIT_INVERT); @@ -571,14 +636,6 @@ static int hashlimit_mt_check(const struct xt_mtchk_param *par) struct xt_hashlimit_mtinfo1 *info = par->matchinfo; int ret; - /* Check for overflow. */ - if (info->cfg.burst == 0 || - user2credits(info->cfg.avg * info->cfg.burst) < - user2credits(info->cfg.avg)) { - pr_info("overflow, try lower: %u/%u\n", - info->cfg.avg, info->cfg.burst); - return -ERANGE; - } if (info->cfg.gc_interval == 0 || info->cfg.expire == 0) return -EINVAL; if (info->name[sizeof(info->name)-1] != '\0') @@ -591,6 +648,26 @@ static int hashlimit_mt_check(const struct xt_mtchk_param *par) return -EINVAL; } + if (info->cfg.mode >= XT_HASHLIMIT_MAX) { + pr_info("Unknown mode mask %X, kernel too old?\n", + info->cfg.mode); + return -EINVAL; + } + + /* Check for overflow. */ + if (info->cfg.mode & XT_HASHLIMIT_BYTES) { + if (user2credits_byte(info->cfg.avg) == 0) { + pr_info("overflow, rate too high: %u\n", info->cfg.avg); + return -EINVAL; + } + } else if (info->cfg.burst == 0 || + user2credits(info->cfg.avg * info->cfg.burst) < + user2credits(info->cfg.avg)) { + pr_info("overflow, try lower: %u/%u\n", + info->cfg.avg, info->cfg.burst); + return -ERANGE; + } + mutex_lock(&hashlimit_mutex); info->hinfo = htable_find_get(net, info->name, par->family); if (info->hinfo == NULL) { @@ -683,10 +760,11 @@ static int dl_seq_real_show(struct dsthash_ent *ent, u_int8_t family, struct seq_file *s) { int res; + const struct xt_hashlimit_htable *ht = s->private; spin_lock(&ent->lock); /* recalculate to show accurate numbers */ - rateinfo_recalc(ent, jiffies); + rateinfo_recalc(ent, jiffies, ht->cfg.mode); switch (family) { case NFPROTO_IPV4: -- 2.7.4