diff options
Diffstat (limited to 'net/netfilter/xt_hashlimit.c')
| -rw-r--r-- | net/netfilter/xt_hashlimit.c | 1332 |
1 files changed, 1332 insertions, 0 deletions
diff --git a/net/netfilter/xt_hashlimit.c b/net/netfilter/xt_hashlimit.c new file mode 100644 index 000000000..0859b8f76 --- /dev/null +++ b/net/netfilter/xt_hashlimit.c @@ -0,0 +1,1332 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * xt_hashlimit - Netfilter module to limit the number of packets per time + * separately for each hashbucket (sourceip/sourceport/dstip/dstport) + * + * (C) 2003-2004 by Harald Welte <laforge@netfilter.org> + * (C) 2006-2012 Patrick McHardy <kaber@trash.net> + * Copyright © CC Computer Consultants GmbH, 2007 - 2008 + * + * Development of this code was funded by Astaro AG, http://www.astaro.com/ + */ +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt +#include <linux/module.h> +#include <linux/spinlock.h> +#include <linux/random.h> +#include <linux/jhash.h> +#include <linux/slab.h> +#include <linux/vmalloc.h> +#include <linux/proc_fs.h> +#include <linux/seq_file.h> +#include <linux/list.h> +#include <linux/skbuff.h> +#include <linux/mm.h> +#include <linux/in.h> +#include <linux/ip.h> +#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES) +#include <linux/ipv6.h> +#include <net/ipv6.h> +#endif + +#include <net/net_namespace.h> +#include <net/netns/generic.h> + +#include <linux/netfilter/x_tables.h> +#include <linux/netfilter_ipv4/ip_tables.h> +#include <linux/netfilter_ipv6/ip6_tables.h> +#include <linux/mutex.h> +#include <linux/kernel.h> +#include <linux/refcount.h> +#include <uapi/linux/netfilter/xt_hashlimit.h> + +#define XT_HASHLIMIT_ALL (XT_HASHLIMIT_HASH_DIP | XT_HASHLIMIT_HASH_DPT | \ + XT_HASHLIMIT_HASH_SIP | XT_HASHLIMIT_HASH_SPT | \ + XT_HASHLIMIT_INVERT | XT_HASHLIMIT_BYTES |\ + XT_HASHLIMIT_RATE_MATCH) + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>"); +MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>"); +MODULE_DESCRIPTION("Xtables: per hash-bucket rate-limit match"); +MODULE_ALIAS("ipt_hashlimit"); +MODULE_ALIAS("ip6t_hashlimit"); + +struct hashlimit_net { + struct hlist_head htables; + struct proc_dir_entry *ipt_hashlimit; + struct proc_dir_entry *ip6t_hashlimit; +}; + +static unsigned int hashlimit_net_id; +static inline struct hashlimit_net *hashlimit_pernet(struct net *net) +{ + return net_generic(net, hashlimit_net_id); +} + +/* need to declare this at the top */ +static const struct seq_operations dl_seq_ops_v2; +static const struct seq_operations dl_seq_ops_v1; +static const struct seq_operations dl_seq_ops; + +/* hash table crap */ +struct dsthash_dst { + union { + struct { + __be32 src; + __be32 dst; + } ip; +#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES) + struct { + __be32 src[4]; + __be32 dst[4]; + } ip6; +#endif + }; + __be16 src_port; + __be16 dst_port; +}; + +struct dsthash_ent { + /* static / read-only parts in the beginning */ + struct hlist_node node; + struct dsthash_dst dst; + + /* modified structure members in the end */ + spinlock_t lock; + unsigned long expires; /* precalculated expiry time */ + struct { + unsigned long prev; /* last modification */ + union { + struct { + u_int64_t credit; + u_int64_t credit_cap; + u_int64_t cost; + }; + struct { + u_int32_t interval, prev_window; + u_int64_t current_rate; + u_int64_t rate; + int64_t burst; + }; + }; + } rateinfo; + struct rcu_head rcu; +}; + +struct xt_hashlimit_htable { + struct hlist_node node; /* global list of all htables */ + refcount_t use; + u_int8_t family; + bool rnd_initialized; + + struct hashlimit_cfg3 cfg; /* config */ + + /* used internally */ + spinlock_t lock; /* lock for list_head */ + u_int32_t rnd; /* random seed for hash */ + unsigned int count; /* number entries in table */ + struct delayed_work gc_work; + + /* seq_file stuff */ + struct proc_dir_entry *pde; + const char *name; + struct net *net; + + struct hlist_head hash[]; /* hashtable itself */ +}; + +static int +cfg_copy(struct hashlimit_cfg3 *to, const void *from, int revision) +{ + if (revision == 1) { + struct hashlimit_cfg1 *cfg = (struct hashlimit_cfg1 *)from; + + to->mode = cfg->mode; + to->avg = cfg->avg; + to->burst = cfg->burst; + to->size = cfg->size; + to->max = cfg->max; + to->gc_interval = cfg->gc_interval; + to->expire = cfg->expire; + to->srcmask = cfg->srcmask; + to->dstmask = cfg->dstmask; + } else if (revision == 2) { + struct hashlimit_cfg2 *cfg = (struct hashlimit_cfg2 *)from; + + to->mode = cfg->mode; + to->avg = cfg->avg; + to->burst = cfg->burst; + to->size = cfg->size; + to->max = cfg->max; + to->gc_interval = cfg->gc_interval; + to->expire = cfg->expire; + to->srcmask = cfg->srcmask; + to->dstmask = cfg->dstmask; + } else if (revision == 3) { + memcpy(to, from, sizeof(struct hashlimit_cfg3)); + } else { + return -EINVAL; + } + + return 0; +} + +static DEFINE_MUTEX(hashlimit_mutex); /* protects htables list */ +static struct kmem_cache *hashlimit_cachep __read_mostly; + +static inline bool dst_cmp(const struct dsthash_ent *ent, + const struct dsthash_dst *b) +{ + return !memcmp(&ent->dst, b, sizeof(ent->dst)); +} + +static u_int32_t +hash_dst(const struct xt_hashlimit_htable *ht, const struct dsthash_dst *dst) +{ + u_int32_t hash = jhash2((const u32 *)dst, + sizeof(*dst)/sizeof(u32), + ht->rnd); + /* + * Instead of returning hash % ht->cfg.size (implying a divide) + * we return the high 32 bits of the (hash * ht->cfg.size) that will + * give results between [0 and cfg.size-1] and same hash distribution, + * but using a multiply, less expensive than a divide + */ + return reciprocal_scale(hash, ht->cfg.size); +} + +static struct dsthash_ent * +dsthash_find(const struct xt_hashlimit_htable *ht, + const struct dsthash_dst *dst) +{ + struct dsthash_ent *ent; + u_int32_t hash = hash_dst(ht, dst); + + if (!hlist_empty(&ht->hash[hash])) { + hlist_for_each_entry_rcu(ent, &ht->hash[hash], node) + if (dst_cmp(ent, dst)) { + spin_lock(&ent->lock); + return ent; + } + } + return NULL; +} + +/* allocate dsthash_ent, initialize dst, put in htable and lock it */ +static struct dsthash_ent * +dsthash_alloc_init(struct xt_hashlimit_htable *ht, + const struct dsthash_dst *dst, bool *race) +{ + struct dsthash_ent *ent; + + spin_lock(&ht->lock); + + /* Two or more packets may race to create the same entry in the + * hashtable, double check if this packet lost race. + */ + ent = dsthash_find(ht, dst); + if (ent != NULL) { + spin_unlock(&ht->lock); + *race = true; + return ent; + } + + /* initialize hash with random val at the time we allocate + * the first hashtable entry */ + if (unlikely(!ht->rnd_initialized)) { + get_random_bytes(&ht->rnd, sizeof(ht->rnd)); + ht->rnd_initialized = true; + } + + if (ht->cfg.max && ht->count >= ht->cfg.max) { + /* FIXME: do something. question is what.. */ + net_err_ratelimited("max count of %u reached\n", ht->cfg.max); + ent = NULL; + } else + ent = kmem_cache_alloc(hashlimit_cachep, GFP_ATOMIC); + if (ent) { + memcpy(&ent->dst, dst, sizeof(ent->dst)); + spin_lock_init(&ent->lock); + + spin_lock(&ent->lock); + hlist_add_head_rcu(&ent->node, &ht->hash[hash_dst(ht, dst)]); + ht->count++; + } + spin_unlock(&ht->lock); + return ent; +} + +static void dsthash_free_rcu(struct rcu_head *head) +{ + struct dsthash_ent *ent = container_of(head, struct dsthash_ent, rcu); + + kmem_cache_free(hashlimit_cachep, ent); +} + +static inline void +dsthash_free(struct xt_hashlimit_htable *ht, struct dsthash_ent *ent) +{ + hlist_del_rcu(&ent->node); + call_rcu(&ent->rcu, dsthash_free_rcu); + ht->count--; +} +static void htable_gc(struct work_struct *work); + +static int htable_create(struct net *net, struct hashlimit_cfg3 *cfg, + const char *name, u_int8_t family, + struct xt_hashlimit_htable **out_hinfo, + int revision) +{ + struct hashlimit_net *hashlimit_net = hashlimit_pernet(net); + struct xt_hashlimit_htable *hinfo; + const struct seq_operations *ops; + unsigned int size, i; + unsigned long nr_pages = totalram_pages(); + int ret; + + if (cfg->size) { + size = cfg->size; + } else { + size = (nr_pages << PAGE_SHIFT) / 16384 / + sizeof(struct hlist_head); + if (nr_pages > 1024 * 1024 * 1024 / PAGE_SIZE) + size = 8192; + if (size < 16) + size = 16; + } + /* FIXME: don't use vmalloc() here or anywhere else -HW */ + hinfo = vmalloc(struct_size(hinfo, hash, size)); + if (hinfo == NULL) + return -ENOMEM; + *out_hinfo = hinfo; + + /* copy match config into hashtable config */ + ret = cfg_copy(&hinfo->cfg, (void *)cfg, 3); + if (ret) { + vfree(hinfo); + return ret; + } + + hinfo->cfg.size = size; + if (hinfo->cfg.max == 0) + hinfo->cfg.max = 8 * hinfo->cfg.size; + else if (hinfo->cfg.max < hinfo->cfg.size) + hinfo->cfg.max = hinfo->cfg.size; + + for (i = 0; i < hinfo->cfg.size; i++) + INIT_HLIST_HEAD(&hinfo->hash[i]); + + refcount_set(&hinfo->use, 1); + hinfo->count = 0; + hinfo->family = family; + hinfo->rnd_initialized = false; + hinfo->name = kstrdup(name, GFP_KERNEL); + if (!hinfo->name) { + vfree(hinfo); + return -ENOMEM; + } + spin_lock_init(&hinfo->lock); + + switch (revision) { + case 1: + ops = &dl_seq_ops_v1; + break; + case 2: + ops = &dl_seq_ops_v2; + break; + default: + ops = &dl_seq_ops; + } + + hinfo->pde = proc_create_seq_data(name, 0, + (family == NFPROTO_IPV4) ? + hashlimit_net->ipt_hashlimit : hashlimit_net->ip6t_hashlimit, + ops, hinfo); + if (hinfo->pde == NULL) { + kfree(hinfo->name); + vfree(hinfo); + return -ENOMEM; + } + hinfo->net = net; + + INIT_DEFERRABLE_WORK(&hinfo->gc_work, htable_gc); + queue_delayed_work(system_power_efficient_wq, &hinfo->gc_work, + msecs_to_jiffies(hinfo->cfg.gc_interval)); + + hlist_add_head(&hinfo->node, &hashlimit_net->htables); + + return 0; +} + +static void htable_selective_cleanup(struct xt_hashlimit_htable *ht, bool select_all) +{ + unsigned int i; + + for (i = 0; i < ht->cfg.size; i++) { + struct dsthash_ent *dh; + struct hlist_node *n; + + spin_lock_bh(&ht->lock); + hlist_for_each_entry_safe(dh, n, &ht->hash[i], node) { + if (time_after_eq(jiffies, dh->expires) || select_all) + dsthash_free(ht, dh); + } + spin_unlock_bh(&ht->lock); + cond_resched(); + } +} + +static void htable_gc(struct work_struct *work) +{ + struct xt_hashlimit_htable *ht; + + ht = container_of(work, struct xt_hashlimit_htable, gc_work.work); + + htable_selective_cleanup(ht, false); + + queue_delayed_work(system_power_efficient_wq, + &ht->gc_work, msecs_to_jiffies(ht->cfg.gc_interval)); +} + +static void htable_remove_proc_entry(struct xt_hashlimit_htable *hinfo) +{ + struct hashlimit_net *hashlimit_net = hashlimit_pernet(hinfo->net); + struct proc_dir_entry *parent; + + if (hinfo->family == NFPROTO_IPV4) + parent = hashlimit_net->ipt_hashlimit; + else + parent = hashlimit_net->ip6t_hashlimit; + + if (parent != NULL) + remove_proc_entry(hinfo->name, parent); +} + +static struct xt_hashlimit_htable *htable_find_get(struct net *net, + const char *name, + u_int8_t family) +{ + struct hashlimit_net *hashlimit_net = hashlimit_pernet(net); + struct xt_hashlimit_htable *hinfo; + + hlist_for_each_entry(hinfo, &hashlimit_net->htables, node) { + if (!strcmp(name, hinfo->name) && + hinfo->family == family) { + refcount_inc(&hinfo->use); + return hinfo; + } + } + return NULL; +} + +static void htable_put(struct xt_hashlimit_htable *hinfo) +{ + if (refcount_dec_and_mutex_lock(&hinfo->use, &hashlimit_mutex)) { + hlist_del(&hinfo->node); + htable_remove_proc_entry(hinfo); + mutex_unlock(&hashlimit_mutex); + + cancel_delayed_work_sync(&hinfo->gc_work); + htable_selective_cleanup(hinfo, true); + kfree(hinfo->name); + vfree(hinfo); + } +} + +/* The algorithm used is the Simple Token Bucket Filter (TBF) + * see net/sched/sch_tbf.c in the linux source tree + */ + +/* Rusty: This is my (non-mathematically-inclined) understanding of + this algorithm. The `average rate' in jiffies becomes your initial + amount of credit `credit' and the most credit you can ever have + `credit_cap'. The `peak rate' becomes the cost of passing the + test, `cost'. + + `prev' tracks the last packet hit: you gain one credit per jiffy. + If you get credit balance more than this, the extra credit is + discarded. Every time the match passes, you lose `cost' credits; + if you don't have that many, the test fails. + + See Alexey's formal explanation in net/sched/sch_tbf.c. + + To get the maximum range, we multiply by this factor (ie. you get N + credits per jiffy). We want to allow a rate as low as 1 per day + (slowest userspace tool allows), which means + CREDITS_PER_JIFFY*HZ*60*60*24 < 2^32 ie. +*/ +#define MAX_CPJ_v1 (0xFFFFFFFF / (HZ*60*60*24)) +#define MAX_CPJ (0xFFFFFFFFFFFFFFFFULL / (HZ*60*60*24)) + +/* Repeated shift and or gives us all 1s, final shift and add 1 gives + * us the power of 2 below the theoretical max, so GCC simply does a + * shift. */ +#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_BELOW64(x) (_POW2_BELOW32(x)|_POW2_BELOW32((x)>>32)) +#define POW2_BELOW32(x) ((_POW2_BELOW32(x)>>1) + 1) +#define POW2_BELOW64(x) ((_POW2_BELOW64(x)>>1) + 1) + +#define CREDITS_PER_JIFFY POW2_BELOW64(MAX_CPJ) +#define CREDITS_PER_JIFFY_v1 POW2_BELOW32(MAX_CPJ_v1) + +/* 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 u64 user2credits(u64 user, int revision) +{ + u64 scale = (revision == 1) ? + XT_HASHLIMIT_SCALE : XT_HASHLIMIT_SCALE_v2; + u64 cpj = (revision == 1) ? + CREDITS_PER_JIFFY_v1 : CREDITS_PER_JIFFY; + + /* Avoid overflow: divide the constant operands first */ + if (scale >= HZ * cpj) + return div64_u64(user, div64_u64(scale, HZ * cpj)); + + return user * div64_u64(HZ * cpj, scale); +} + +static u32 user2credits_byte(u32 user) +{ + u64 us = user; + us *= HZ * CREDITS_PER_JIFFY_BYTES; + return (u32) (us >> 32); +} + +static u64 user2rate(u64 user) +{ + if (user != 0) { + return div64_u64(XT_HASHLIMIT_SCALE_v2, user); + } else { + pr_info_ratelimited("invalid rate from userspace: %llu\n", + user); + return 0; + } +} + +static u64 user2rate_bytes(u32 user) +{ + u64 r; + + r = user ? U32_MAX / user : U32_MAX; + return (r - 1) << XT_HASHLIMIT_BYTE_SHIFT; +} + +static void rateinfo_recalc(struct dsthash_ent *dh, unsigned long now, + u32 mode, int revision) +{ + unsigned long delta = now - dh->rateinfo.prev; + u64 cap, cpj; + + if (delta == 0) + return; + + if (revision >= 3 && mode & XT_HASHLIMIT_RATE_MATCH) { + u64 interval = dh->rateinfo.interval * HZ; + + if (delta < interval) + return; + + dh->rateinfo.prev = now; + dh->rateinfo.prev_window = + ((dh->rateinfo.current_rate * interval) > + (delta * dh->rateinfo.rate)); + dh->rateinfo.current_rate = 0; + + return; + } + + dh->rateinfo.prev = now; + + if (mode & XT_HASHLIMIT_BYTES) { + u64 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 { + cpj = (revision == 1) ? + CREDITS_PER_JIFFY_v1 : CREDITS_PER_JIFFY; + dh->rateinfo.credit += delta * cpj; + 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, int revision) +{ + dh->rateinfo.prev = jiffies; + if (revision >= 3 && hinfo->cfg.mode & XT_HASHLIMIT_RATE_MATCH) { + dh->rateinfo.prev_window = 0; + dh->rateinfo.current_rate = 0; + if (hinfo->cfg.mode & XT_HASHLIMIT_BYTES) { + dh->rateinfo.rate = + user2rate_bytes((u32)hinfo->cfg.avg); + if (hinfo->cfg.burst) + dh->rateinfo.burst = + hinfo->cfg.burst * dh->rateinfo.rate; + else + dh->rateinfo.burst = dh->rateinfo.rate; + } else { + dh->rateinfo.rate = user2rate(hinfo->cfg.avg); + dh->rateinfo.burst = + hinfo->cfg.burst + dh->rateinfo.rate; + } + dh->rateinfo.interval = hinfo->cfg.interval; + } else 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, revision); + dh->rateinfo.cost = user2credits(hinfo->cfg.avg, revision); + dh->rateinfo.credit_cap = dh->rateinfo.credit; + } +} + +static inline __be32 maskl(__be32 a, unsigned int l) +{ + return l ? htonl(ntohl(a) & ~0 << (32 - l)) : 0; +} + +#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES) +static void hashlimit_ipv6_mask(__be32 *i, unsigned int p) +{ + switch (p) { + case 0 ... 31: + i[0] = maskl(i[0], p); + i[1] = i[2] = i[3] = 0; + break; + case 32 ... 63: + i[1] = maskl(i[1], p - 32); + i[2] = i[3] = 0; + break; + case 64 ... 95: + i[2] = maskl(i[2], p - 64); + i[3] = 0; + break; + case 96 ... 127: + i[3] = maskl(i[3], p - 96); + break; + case 128: + break; + } +} +#endif + +static int +hashlimit_init_dst(const struct xt_hashlimit_htable *hinfo, + struct dsthash_dst *dst, + const struct sk_buff *skb, unsigned int protoff) +{ + __be16 _ports[2], *ports; + u8 nexthdr; + int poff; + + memset(dst, 0, sizeof(*dst)); + + switch (hinfo->family) { + case NFPROTO_IPV4: + if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DIP) + dst->ip.dst = maskl(ip_hdr(skb)->daddr, + hinfo->cfg.dstmask); + if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SIP) + dst->ip.src = maskl(ip_hdr(skb)->saddr, + hinfo->cfg.srcmask); + + if (!(hinfo->cfg.mode & + (XT_HASHLIMIT_HASH_DPT | XT_HASHLIMIT_HASH_SPT))) + return 0; + nexthdr = ip_hdr(skb)->protocol; + break; +#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES) + case NFPROTO_IPV6: + { + __be16 frag_off; + + if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DIP) { + memcpy(&dst->ip6.dst, &ipv6_hdr(skb)->daddr, + sizeof(dst->ip6.dst)); + hashlimit_ipv6_mask(dst->ip6.dst, hinfo->cfg.dstmask); + } + if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SIP) { + memcpy(&dst->ip6.src, &ipv6_hdr(skb)->saddr, + sizeof(dst->ip6.src)); + hashlimit_ipv6_mask(dst->ip6.src, hinfo->cfg.srcmask); + } + + if (!(hinfo->cfg.mode & + (XT_HASHLIMIT_HASH_DPT | XT_HASHLIMIT_HASH_SPT))) + return 0; + nexthdr = ipv6_hdr(skb)->nexthdr; + protoff = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr), &nexthdr, &frag_off); + if ((int)protoff < 0) + return -1; + break; + } +#endif + default: + BUG(); + return 0; + } + + poff = proto_ports_offset(nexthdr); + if (poff >= 0) { + ports = skb_header_pointer(skb, protoff + poff, sizeof(_ports), + &_ports); + } else { + _ports[0] = _ports[1] = 0; + ports = _ports; + } + if (!ports) + return -1; + if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_SPT) + dst->src_port = ports[0]; + if (hinfo->cfg.mode & XT_HASHLIMIT_HASH_DPT) + dst->dst_port = ports[1]; + 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_common(const struct sk_buff *skb, struct xt_action_param *par, + struct xt_hashlimit_htable *hinfo, + const struct hashlimit_cfg3 *cfg, int revision) +{ + unsigned long now = jiffies; + struct dsthash_ent *dh; + struct dsthash_dst dst; + bool race = false; + u64 cost; + + if (hashlimit_init_dst(hinfo, &dst, skb, par->thoff) < 0) + goto hotdrop; + + local_bh_disable(); + dh = dsthash_find(hinfo, &dst); + if (dh == NULL) { + dh = dsthash_alloc_init(hinfo, &dst, &race); + if (dh == NULL) { + local_bh_enable(); + goto hotdrop; + } else if (race) { + /* Already got an entry, update expiration timeout */ + dh->expires = now + msecs_to_jiffies(hinfo->cfg.expire); + rateinfo_recalc(dh, now, hinfo->cfg.mode, revision); + } else { + dh->expires = jiffies + msecs_to_jiffies(hinfo->cfg.expire); + rateinfo_init(dh, hinfo, revision); + } + } else { + /* update expiration timeout */ + dh->expires = now + msecs_to_jiffies(hinfo->cfg.expire); + rateinfo_recalc(dh, now, hinfo->cfg.mode, revision); + } + + if (cfg->mode & XT_HASHLIMIT_RATE_MATCH) { + cost = (cfg->mode & XT_HASHLIMIT_BYTES) ? skb->len : 1; + dh->rateinfo.current_rate += cost; + + if (!dh->rateinfo.prev_window && + (dh->rateinfo.current_rate <= dh->rateinfo.burst)) { + spin_unlock(&dh->lock); + local_bh_enable(); + return !(cfg->mode & XT_HASHLIMIT_INVERT); + } else { + goto overlimit; + } + } + + if (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 -= cost; + spin_unlock(&dh->lock); + local_bh_enable(); + return !(cfg->mode & XT_HASHLIMIT_INVERT); + } + +overlimit: + spin_unlock(&dh->lock); + local_bh_enable(); + /* default match is underlimit - so over the limit, we need to invert */ + return cfg->mode & XT_HASHLIMIT_INVERT; + + hotdrop: + par->hotdrop = true; + return false; +} + +static bool +hashlimit_mt_v1(const struct sk_buff *skb, struct xt_action_param *par) +{ + const struct xt_hashlimit_mtinfo1 *info = par->matchinfo; + struct xt_hashlimit_htable *hinfo = info->hinfo; + struct hashlimit_cfg3 cfg = {}; + int ret; + + ret = cfg_copy(&cfg, (void *)&info->cfg, 1); + if (ret) + return ret; + + return hashlimit_mt_common(skb, par, hinfo, &cfg, 1); +} + +static bool +hashlimit_mt_v2(const struct sk_buff *skb, struct xt_action_param *par) +{ + const struct xt_hashlimit_mtinfo2 *info = par->matchinfo; + struct xt_hashlimit_htable *hinfo = info->hinfo; + struct hashlimit_cfg3 cfg = {}; + int ret; + + ret = cfg_copy(&cfg, (void *)&info->cfg, 2); + if (ret) + return ret; + + return hashlimit_mt_common(skb, par, hinfo, &cfg, 2); +} + +static bool +hashlimit_mt(const struct sk_buff *skb, struct xt_action_param *par) +{ + const struct xt_hashlimit_mtinfo3 *info = par->matchinfo; + struct xt_hashlimit_htable *hinfo = info->hinfo; + + return hashlimit_mt_common(skb, par, hinfo, &info->cfg, 3); +} + +#define HASHLIMIT_MAX_SIZE 1048576 + +static int hashlimit_mt_check_common(const struct xt_mtchk_param *par, + struct xt_hashlimit_htable **hinfo, + struct hashlimit_cfg3 *cfg, + const char *name, int revision) +{ + struct net *net = par->net; + int ret; + + if (cfg->gc_interval == 0 || cfg->expire == 0) + return -EINVAL; + if (cfg->size > HASHLIMIT_MAX_SIZE) { + cfg->size = HASHLIMIT_MAX_SIZE; + pr_info_ratelimited("size too large, truncated to %u\n", cfg->size); + } + if (cfg->max > HASHLIMIT_MAX_SIZE) { + cfg->max = HASHLIMIT_MAX_SIZE; + pr_info_ratelimited("max too large, truncated to %u\n", cfg->max); + } + if (par->family == NFPROTO_IPV4) { + if (cfg->srcmask > 32 || cfg->dstmask > 32) + return -EINVAL; + } else { + if (cfg->srcmask > 128 || cfg->dstmask > 128) + return -EINVAL; + } + + if (cfg->mode & ~XT_HASHLIMIT_ALL) { + pr_info_ratelimited("Unknown mode mask %X, kernel too old?\n", + cfg->mode); + return -EINVAL; + } + + /* Check for overflow. */ + if (revision >= 3 && cfg->mode & XT_HASHLIMIT_RATE_MATCH) { + if (cfg->avg == 0 || cfg->avg > U32_MAX) { + pr_info_ratelimited("invalid rate\n"); + return -ERANGE; + } + + if (cfg->interval == 0) { + pr_info_ratelimited("invalid interval\n"); + return -EINVAL; + } + } else if (cfg->mode & XT_HASHLIMIT_BYTES) { + if (user2credits_byte(cfg->avg) == 0) { + pr_info_ratelimited("overflow, rate too high: %llu\n", + cfg->avg); + return -EINVAL; + } + } else if (cfg->burst == 0 || + user2credits(cfg->avg * cfg->burst, revision) < + user2credits(cfg->avg, revision)) { + pr_info_ratelimited("overflow, try lower: %llu/%llu\n", + cfg->avg, cfg->burst); + return -ERANGE; + } + + mutex_lock(&hashlimit_mutex); + *hinfo = htable_find_get(net, name, par->family); + if (*hinfo == NULL) { + ret = htable_create(net, cfg, name, par->family, + hinfo, revision); + if (ret < 0) { + mutex_unlock(&hashlimit_mutex); + return ret; + } + } + mutex_unlock(&hashlimit_mutex); + + return 0; +} + +static int hashlimit_mt_check_v1(const struct xt_mtchk_param *par) +{ + struct xt_hashlimit_mtinfo1 *info = par->matchinfo; + struct hashlimit_cfg3 cfg = {}; + int ret; + + ret = xt_check_proc_name(info->name, sizeof(info->name)); + if (ret) + return ret; + + ret = cfg_copy(&cfg, (void *)&info->cfg, 1); + if (ret) + return ret; + + return hashlimit_mt_check_common(par, &info->hinfo, + &cfg, info->name, 1); +} + +static int hashlimit_mt_check_v2(const struct xt_mtchk_param *par) +{ + struct xt_hashlimit_mtinfo2 *info = par->matchinfo; + struct hashlimit_cfg3 cfg = {}; + int ret; + + ret = xt_check_proc_name(info->name, sizeof(info->name)); + if (ret) + return ret; + + ret = cfg_copy(&cfg, (void *)&info->cfg, 2); + if (ret) + return ret; + + return hashlimit_mt_check_common(par, &info->hinfo, + &cfg, info->name, 2); +} + +static int hashlimit_mt_check(const struct xt_mtchk_param *par) +{ + struct xt_hashlimit_mtinfo3 *info = par->matchinfo; + int ret; + + ret = xt_check_proc_name(info->name, sizeof(info->name)); + if (ret) + return ret; + + return hashlimit_mt_check_common(par, &info->hinfo, &info->cfg, + info->name, 3); +} + +static void hashlimit_mt_destroy_v2(const struct xt_mtdtor_param *par) +{ + const struct xt_hashlimit_mtinfo2 *info = par->matchinfo; + + htable_put(info->hinfo); +} + +static void hashlimit_mt_destroy_v1(const struct xt_mtdtor_param *par) +{ + const struct xt_hashlimit_mtinfo1 *info = par->matchinfo; + + htable_put(info->hinfo); +} + +static void hashlimit_mt_destroy(const struct xt_mtdtor_param *par) +{ + const struct xt_hashlimit_mtinfo3 *info = par->matchinfo; + + htable_put(info->hinfo); +} + +static struct xt_match hashlimit_mt_reg[] __read_mostly = { + { + .name = "hashlimit", + .revision = 1, + .family = NFPROTO_IPV4, + .match = hashlimit_mt_v1, + .matchsize = sizeof(struct xt_hashlimit_mtinfo1), + .usersize = offsetof(struct xt_hashlimit_mtinfo1, hinfo), + .checkentry = hashlimit_mt_check_v1, + .destroy = hashlimit_mt_destroy_v1, + .me = THIS_MODULE, + }, + { + .name = "hashlimit", + .revision = 2, + .family = NFPROTO_IPV4, + .match = hashlimit_mt_v2, + .matchsize = sizeof(struct xt_hashlimit_mtinfo2), + .usersize = offsetof(struct xt_hashlimit_mtinfo2, hinfo), + .checkentry = hashlimit_mt_check_v2, + .destroy = hashlimit_mt_destroy_v2, + .me = THIS_MODULE, + }, + { + .name = "hashlimit", + .revision = 3, + .family = NFPROTO_IPV4, + .match = hashlimit_mt, + .matchsize = sizeof(struct xt_hashlimit_mtinfo3), + .usersize = offsetof(struct xt_hashlimit_mtinfo3, hinfo), + .checkentry = hashlimit_mt_check, + .destroy = hashlimit_mt_destroy, + .me = THIS_MODULE, + }, +#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES) + { + .name = "hashlimit", + .revision = 1, + .family = NFPROTO_IPV6, + .match = hashlimit_mt_v1, + .matchsize = sizeof(struct xt_hashlimit_mtinfo1), + .usersize = offsetof(struct xt_hashlimit_mtinfo1, hinfo), + .checkentry = hashlimit_mt_check_v1, + .destroy = hashlimit_mt_destroy_v1, + .me = THIS_MODULE, + }, + { + .name = "hashlimit", + .revision = 2, + .family = NFPROTO_IPV6, + .match = hashlimit_mt_v2, + .matchsize = sizeof(struct xt_hashlimit_mtinfo2), + .usersize = offsetof(struct xt_hashlimit_mtinfo2, hinfo), + .checkentry = hashlimit_mt_check_v2, + .destroy = hashlimit_mt_destroy_v2, + .me = THIS_MODULE, + }, + { + .name = "hashlimit", + .revision = 3, + .family = NFPROTO_IPV6, + .match = hashlimit_mt, + .matchsize = sizeof(struct xt_hashlimit_mtinfo3), + .usersize = offsetof(struct xt_hashlimit_mtinfo3, hinfo), + .checkentry = hashlimit_mt_check, + .destroy = hashlimit_mt_destroy, + .me = THIS_MODULE, + }, +#endif +}; + +/* PROC stuff */ +static void *dl_seq_start(struct seq_file *s, loff_t *pos) + __acquires(htable->lock) +{ + struct xt_hashlimit_htable *htable = pde_data(file_inode(s->file)); + unsigned int *bucket; + + spin_lock_bh(&htable->lock); + if (*pos >= htable->cfg.size) + return NULL; + + bucket = kmalloc(sizeof(unsigned int), GFP_ATOMIC); + if (!bucket) + return ERR_PTR(-ENOMEM); + + *bucket = *pos; + return bucket; +} + +static void *dl_seq_next(struct seq_file *s, void *v, loff_t *pos) +{ + struct xt_hashlimit_htable *htable = pde_data(file_inode(s->file)); + unsigned int *bucket = v; + + *pos = ++(*bucket); + if (*pos >= htable->cfg.size) { + kfree(v); + return NULL; + } + return bucket; +} + +static void dl_seq_stop(struct seq_file *s, void *v) + __releases(htable->lock) +{ + struct xt_hashlimit_htable *htable = pde_data(file_inode(s->file)); + unsigned int *bucket = v; + + if (!IS_ERR(bucket)) + kfree(bucket); + spin_unlock_bh(&htable->lock); +} + +static void dl_seq_print(struct dsthash_ent *ent, u_int8_t family, + struct seq_file *s) +{ + switch (family) { + case NFPROTO_IPV4: + seq_printf(s, "%ld %pI4:%u->%pI4:%u %llu %llu %llu\n", + (long)(ent->expires - jiffies)/HZ, + &ent->dst.ip.src, + ntohs(ent->dst.src_port), + &ent->dst.ip.dst, + ntohs(ent->dst.dst_port), + ent->rateinfo.credit, ent->rateinfo.credit_cap, + ent->rateinfo.cost); + break; +#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES) + case NFPROTO_IPV6: + seq_printf(s, "%ld %pI6:%u->%pI6:%u %llu %llu %llu\n", + (long)(ent->expires - jiffies)/HZ, + &ent->dst.ip6.src, + ntohs(ent->dst.src_port), + &ent->dst.ip6.dst, + ntohs(ent->dst.dst_port), + ent->rateinfo.credit, ent->rateinfo.credit_cap, + ent->rateinfo.cost); + break; +#endif + default: + BUG(); + } +} + +static int dl_seq_real_show_v2(struct dsthash_ent *ent, u_int8_t family, + struct seq_file *s) +{ + struct xt_hashlimit_htable *ht = pde_data(file_inode(s->file)); + + spin_lock(&ent->lock); + /* recalculate to show accurate numbers */ + rateinfo_recalc(ent, jiffies, ht->cfg.mode, 2); + + dl_seq_print(ent, family, s); + + spin_unlock(&ent->lock); + return seq_has_overflowed(s); +} + +static int dl_seq_real_show_v1(struct dsthash_ent *ent, u_int8_t family, + struct seq_file *s) +{ + struct xt_hashlimit_htable *ht = pde_data(file_inode(s->file)); + + spin_lock(&ent->lock); + /* recalculate to show accurate numbers */ + rateinfo_recalc(ent, jiffies, ht->cfg.mode, 1); + + dl_seq_print(ent, family, s); + + spin_unlock(&ent->lock); + return seq_has_overflowed(s); +} + +static int dl_seq_real_show(struct dsthash_ent *ent, u_int8_t family, + struct seq_file *s) +{ + struct xt_hashlimit_htable *ht = pde_data(file_inode(s->file)); + + spin_lock(&ent->lock); + /* recalculate to show accurate numbers */ + rateinfo_recalc(ent, jiffies, ht->cfg.mode, 3); + + dl_seq_print(ent, family, s); + + spin_unlock(&ent->lock); + return seq_has_overflowed(s); +} + +static int dl_seq_show_v2(struct seq_file *s, void *v) +{ + struct xt_hashlimit_htable *htable = pde_data(file_inode(s->file)); + unsigned int *bucket = (unsigned int *)v; + struct dsthash_ent *ent; + + if (!hlist_empty(&htable->hash[*bucket])) { + hlist_for_each_entry(ent, &htable->hash[*bucket], node) + if (dl_seq_real_show_v2(ent, htable->family, s)) + return -1; + } + return 0; +} + +static int dl_seq_show_v1(struct seq_file *s, void *v) +{ + struct xt_hashlimit_htable *htable = pde_data(file_inode(s->file)); + unsigned int *bucket = v; + struct dsthash_ent *ent; + + if (!hlist_empty(&htable->hash[*bucket])) { + hlist_for_each_entry(ent, &htable->hash[*bucket], node) + if (dl_seq_real_show_v1(ent, htable->family, s)) + return -1; + } + return 0; +} + +static int dl_seq_show(struct seq_file *s, void *v) +{ + struct xt_hashlimit_htable *htable = pde_data(file_inode(s->file)); + unsigned int *bucket = v; + struct dsthash_ent *ent; + + if (!hlist_empty(&htable->hash[*bucket])) { + hlist_for_each_entry(ent, &htable->hash[*bucket], node) + if (dl_seq_real_show(ent, htable->family, s)) + return -1; + } + return 0; +} + +static const struct seq_operations dl_seq_ops_v1 = { + .start = dl_seq_start, + .next = dl_seq_next, + .stop = dl_seq_stop, + .show = dl_seq_show_v1 +}; + +static const struct seq_operations dl_seq_ops_v2 = { + .start = dl_seq_start, + .next = dl_seq_next, + .stop = dl_seq_stop, + .show = dl_seq_show_v2 +}; + +static const struct seq_operations dl_seq_ops = { + .start = dl_seq_start, + .next = dl_seq_next, + .stop = dl_seq_stop, + .show = dl_seq_show +}; + +static int __net_init hashlimit_proc_net_init(struct net *net) +{ + struct hashlimit_net *hashlimit_net = hashlimit_pernet(net); + + hashlimit_net->ipt_hashlimit = proc_mkdir("ipt_hashlimit", net->proc_net); + if (!hashlimit_net->ipt_hashlimit) + return -ENOMEM; +#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES) + hashlimit_net->ip6t_hashlimit = proc_mkdir("ip6t_hashlimit", net->proc_net); + if (!hashlimit_net->ip6t_hashlimit) { + remove_proc_entry("ipt_hashlimit", net->proc_net); + return -ENOMEM; + } +#endif + return 0; +} + +static void __net_exit hashlimit_proc_net_exit(struct net *net) +{ + struct xt_hashlimit_htable *hinfo; + struct hashlimit_net *hashlimit_net = hashlimit_pernet(net); + + /* hashlimit_net_exit() is called before hashlimit_mt_destroy(). + * Make sure that the parent ipt_hashlimit and ip6t_hashlimit proc + * entries is empty before trying to remove it. + */ + mutex_lock(&hashlimit_mutex); + hlist_for_each_entry(hinfo, &hashlimit_net->htables, node) + htable_remove_proc_entry(hinfo); + hashlimit_net->ipt_hashlimit = NULL; + hashlimit_net->ip6t_hashlimit = NULL; + mutex_unlock(&hashlimit_mutex); + + remove_proc_entry("ipt_hashlimit", net->proc_net); +#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES) + remove_proc_entry("ip6t_hashlimit", net->proc_net); +#endif +} + +static int __net_init hashlimit_net_init(struct net *net) +{ + struct hashlimit_net *hashlimit_net = hashlimit_pernet(net); + + INIT_HLIST_HEAD(&hashlimit_net->htables); + return hashlimit_proc_net_init(net); +} + +static void __net_exit hashlimit_net_exit(struct net *net) +{ + hashlimit_proc_net_exit(net); +} + +static struct pernet_operations hashlimit_net_ops = { + .init = hashlimit_net_init, + .exit = hashlimit_net_exit, + .id = &hashlimit_net_id, + .size = sizeof(struct hashlimit_net), +}; + +static int __init hashlimit_mt_init(void) +{ + int err; + + err = register_pernet_subsys(&hashlimit_net_ops); + if (err < 0) + return err; + err = xt_register_matches(hashlimit_mt_reg, + ARRAY_SIZE(hashlimit_mt_reg)); + if (err < 0) + goto err1; + + err = -ENOMEM; + hashlimit_cachep = kmem_cache_create("xt_hashlimit", + sizeof(struct dsthash_ent), 0, 0, + NULL); + if (!hashlimit_cachep) { + pr_warn("unable to create slab cache\n"); + goto err2; + } + return 0; + +err2: + xt_unregister_matches(hashlimit_mt_reg, ARRAY_SIZE(hashlimit_mt_reg)); +err1: + unregister_pernet_subsys(&hashlimit_net_ops); + return err; + +} + +static void __exit hashlimit_mt_exit(void) +{ + xt_unregister_matches(hashlimit_mt_reg, ARRAY_SIZE(hashlimit_mt_reg)); + unregister_pernet_subsys(&hashlimit_net_ops); + + rcu_barrier(); + kmem_cache_destroy(hashlimit_cachep); +} + +module_init(hashlimit_mt_init); +module_exit(hashlimit_mt_exit); |