// 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 <[email protected]>
* (C) 2006-2012 Patrick McHardy <[email protected]>
* 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 <[email protected]>");
MODULE_AUTHOR("Jan Engelhardt <[email protected]>");
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);
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