blob: 9a4c8ff32d9dd9407ec50591a44008570f4e7411 [file] [log] [blame]
// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2015-2019 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
*/
#include "allowedips.h"
#include "peer.h"
static struct kmem_cache *node_cache;
static void swap_endian(u8 *dst, const u8 *src, u8 bits)
{
if (bits == 32) {
*(u32 *)dst = be32_to_cpu(*(const __be32 *)src);
} else if (bits == 128) {
((u64 *)dst)[0] = be64_to_cpu(((const __be64 *)src)[0]);
((u64 *)dst)[1] = be64_to_cpu(((const __be64 *)src)[1]);
}
}
static void copy_and_assign_cidr(struct allowedips_node *node, const u8 *src,
u8 cidr, u8 bits)
{
node->cidr = cidr;
node->bit_at_a = cidr / 8U;
#ifdef __LITTLE_ENDIAN
node->bit_at_a ^= (bits / 8U - 1U) % 8U;
#endif
node->bit_at_b = 7U - (cidr % 8U);
node->bitlen = bits;
memcpy(node->bits, src, bits / 8U);
}
static inline u8 choose(struct allowedips_node *node, const u8 *key)
{
return (key[node->bit_at_a] >> node->bit_at_b) & 1;
}
static void push_rcu(struct allowedips_node **stack,
struct allowedips_node __rcu *p, unsigned int *len)
{
if (rcu_access_pointer(p)) {
WARN_ON(IS_ENABLED(DEBUG) && *len >= 128);
stack[(*len)++] = rcu_dereference_raw(p);
}
}
static void node_free_rcu(struct rcu_head *rcu)
{
kmem_cache_free(node_cache, container_of(rcu, struct allowedips_node, rcu));
}
static void root_free_rcu(struct rcu_head *rcu)
{
struct allowedips_node *node, *stack[128] = {
container_of(rcu, struct allowedips_node, rcu) };
unsigned int len = 1;
while (len > 0 && (node = stack[--len])) {
push_rcu(stack, node->bit[0], &len);
push_rcu(stack, node->bit[1], &len);
kmem_cache_free(node_cache, node);
}
}
static void root_remove_peer_lists(struct allowedips_node *root)
{
struct allowedips_node *node, *stack[128] = { root };
unsigned int len = 1;
while (len > 0 && (node = stack[--len])) {
push_rcu(stack, node->bit[0], &len);
push_rcu(stack, node->bit[1], &len);
if (rcu_access_pointer(node->peer))
list_del(&node->peer_list);
}
}
static unsigned int fls128(u64 a, u64 b)
{
return a ? fls64(a) + 64U : fls64(b);
}
static u8 common_bits(const struct allowedips_node *node, const u8 *key,
u8 bits)
{
if (bits == 32)
return 32U - fls(*(const u32 *)node->bits ^ *(const u32 *)key);
else if (bits == 128)
return 128U - fls128(
*(const u64 *)&node->bits[0] ^ *(const u64 *)&key[0],
*(const u64 *)&node->bits[8] ^ *(const u64 *)&key[8]);
return 0;
}
static bool prefix_matches(const struct allowedips_node *node, const u8 *key,
u8 bits)
{
/* This could be much faster if it actually just compared the common
* bits properly, by precomputing a mask bswap(~0 << (32 - cidr)), and
* the rest, but it turns out that common_bits is already super fast on
* modern processors, even taking into account the unfortunate bswap.
* So, we just inline it like this instead.
*/
return common_bits(node, key, bits) >= node->cidr;
}
static struct allowedips_node *find_node(struct allowedips_node *trie, u8 bits,
const u8 *key)
{
struct allowedips_node *node = trie, *found = NULL;
while (node && prefix_matches(node, key, bits)) {
if (rcu_access_pointer(node->peer))
found = node;
if (node->cidr == bits)
break;
node = rcu_dereference_bh(node->bit[choose(node, key)]);
}
return found;
}
/* Returns a strong reference to a peer */
static struct wg_peer *lookup(struct allowedips_node __rcu *root, u8 bits,
const void *be_ip)
{
/* Aligned so it can be passed to fls/fls64 */
u8 ip[16] __aligned(__alignof(u64));
struct allowedips_node *node;
struct wg_peer *peer = NULL;
swap_endian(ip, be_ip, bits);
rcu_read_lock_bh();
retry:
node = find_node(rcu_dereference_bh(root), bits, ip);
if (node) {
peer = wg_peer_get_maybe_zero(rcu_dereference_bh(node->peer));
if (!peer)
goto retry;
}
rcu_read_unlock_bh();
return peer;
}
static bool node_placement(struct allowedips_node __rcu *trie, const u8 *key,
u8 cidr, u8 bits, struct allowedips_node **rnode,
struct mutex *lock)
{
struct allowedips_node *node = rcu_dereference_protected(trie, lockdep_is_held(lock));
struct allowedips_node *parent = NULL;
bool exact = false;
while (node && node->cidr <= cidr && prefix_matches(node, key, bits)) {
parent = node;
if (parent->cidr == cidr) {
exact = true;
break;
}
node = rcu_dereference_protected(parent->bit[choose(parent, key)], lockdep_is_held(lock));
}
*rnode = parent;
return exact;
}
static inline void connect_node(struct allowedips_node __rcu **parent, u8 bit, struct allowedips_node *node)
{
node->parent_bit_packed = (unsigned long)parent | bit;
rcu_assign_pointer(*parent, node);
}
static inline void choose_and_connect_node(struct allowedips_node *parent, struct allowedips_node *node)
{
u8 bit = choose(parent, node->bits);
connect_node(&parent->bit[bit], bit, node);
}
static int add(struct allowedips_node __rcu **trie, u8 bits, const u8 *key,
u8 cidr, struct wg_peer *peer, struct mutex *lock)
{
struct allowedips_node *node, *parent, *down, *newnode;
if (unlikely(cidr > bits || !peer))
return -EINVAL;
if (!rcu_access_pointer(*trie)) {
node = kmem_cache_zalloc(node_cache, GFP_KERNEL);
if (unlikely(!node))
return -ENOMEM;
RCU_INIT_POINTER(node->peer, peer);
list_add_tail(&node->peer_list, &peer->allowedips_list);
copy_and_assign_cidr(node, key, cidr, bits);
connect_node(trie, 2, node);
return 0;
}
if (node_placement(*trie, key, cidr, bits, &node, lock)) {
rcu_assign_pointer(node->peer, peer);
list_move_tail(&node->peer_list, &peer->allowedips_list);
return 0;
}
newnode = kmem_cache_zalloc(node_cache, GFP_KERNEL);
if (unlikely(!newnode))
return -ENOMEM;
RCU_INIT_POINTER(newnode->peer, peer);
list_add_tail(&newnode->peer_list, &peer->allowedips_list);
copy_and_assign_cidr(newnode, key, cidr, bits);
if (!node) {
down = rcu_dereference_protected(*trie, lockdep_is_held(lock));
} else {
const u8 bit = choose(node, key);
down = rcu_dereference_protected(node->bit[bit], lockdep_is_held(lock));
if (!down) {
connect_node(&node->bit[bit], bit, newnode);
return 0;
}
}
cidr = min(cidr, common_bits(down, key, bits));
parent = node;
if (newnode->cidr == cidr) {
choose_and_connect_node(newnode, down);
if (!parent)
connect_node(trie, 2, newnode);
else
choose_and_connect_node(parent, newnode);
return 0;
}
node = kmem_cache_zalloc(node_cache, GFP_KERNEL);
if (unlikely(!node)) {
list_del(&newnode->peer_list);
kmem_cache_free(node_cache, newnode);
return -ENOMEM;
}
INIT_LIST_HEAD(&node->peer_list);
copy_and_assign_cidr(node, newnode->bits, cidr, bits);
choose_and_connect_node(node, down);
choose_and_connect_node(node, newnode);
if (!parent)
connect_node(trie, 2, node);
else
choose_and_connect_node(parent, node);
return 0;
}
void wg_allowedips_init(struct allowedips *table)
{
table->root4 = table->root6 = NULL;
table->seq = 1;
}
void wg_allowedips_free(struct allowedips *table, struct mutex *lock)
{
struct allowedips_node __rcu *old4 = table->root4, *old6 = table->root6;
++table->seq;
RCU_INIT_POINTER(table->root4, NULL);
RCU_INIT_POINTER(table->root6, NULL);
if (rcu_access_pointer(old4)) {
struct allowedips_node *node = rcu_dereference_protected(old4,
lockdep_is_held(lock));
root_remove_peer_lists(node);
call_rcu(&node->rcu, root_free_rcu);
}
if (rcu_access_pointer(old6)) {
struct allowedips_node *node = rcu_dereference_protected(old6,
lockdep_is_held(lock));
root_remove_peer_lists(node);
call_rcu(&node->rcu, root_free_rcu);
}
}
int wg_allowedips_insert_v4(struct allowedips *table, const struct in_addr *ip,
u8 cidr, struct wg_peer *peer, struct mutex *lock)
{
/* Aligned so it can be passed to fls */
u8 key[4] __aligned(__alignof(u32));
++table->seq;
swap_endian(key, (const u8 *)ip, 32);
return add(&table->root4, 32, key, cidr, peer, lock);
}
int wg_allowedips_insert_v6(struct allowedips *table, const struct in6_addr *ip,
u8 cidr, struct wg_peer *peer, struct mutex *lock)
{
/* Aligned so it can be passed to fls64 */
u8 key[16] __aligned(__alignof(u64));
++table->seq;
swap_endian(key, (const u8 *)ip, 128);
return add(&table->root6, 128, key, cidr, peer, lock);
}
void wg_allowedips_remove_by_peer(struct allowedips *table,
struct wg_peer *peer, struct mutex *lock)
{
struct allowedips_node *node, *child, **parent_bit, *parent, *tmp;
bool free_parent;
if (list_empty(&peer->allowedips_list))
return;
++table->seq;
list_for_each_entry_safe(node, tmp, &peer->allowedips_list, peer_list) {
list_del_init(&node->peer_list);
RCU_INIT_POINTER(node->peer, NULL);
if (node->bit[0] && node->bit[1])
continue;
child = rcu_dereference_protected(node->bit[!rcu_access_pointer(node->bit[0])],
lockdep_is_held(lock));
if (child)
child->parent_bit_packed = node->parent_bit_packed;
parent_bit = (struct allowedips_node **)(node->parent_bit_packed & ~3UL);
*parent_bit = child;
parent = (void *)parent_bit -
offsetof(struct allowedips_node, bit[node->parent_bit_packed & 1]);
free_parent = !rcu_access_pointer(node->bit[0]) &&
!rcu_access_pointer(node->bit[1]) &&
(node->parent_bit_packed & 3) <= 1 &&
!rcu_access_pointer(parent->peer);
if (free_parent)
child = rcu_dereference_protected(
parent->bit[!(node->parent_bit_packed & 1)],
lockdep_is_held(lock));
call_rcu(&node->rcu, node_free_rcu);
if (!free_parent)
continue;
if (child)
child->parent_bit_packed = parent->parent_bit_packed;
*(struct allowedips_node **)(parent->parent_bit_packed & ~3UL) = child;
call_rcu(&parent->rcu, node_free_rcu);
}
}
int wg_allowedips_read_node(struct allowedips_node *node, u8 ip[16], u8 *cidr)
{
const unsigned int cidr_bytes = DIV_ROUND_UP(node->cidr, 8U);
swap_endian(ip, node->bits, node->bitlen);
memset(ip + cidr_bytes, 0, node->bitlen / 8U - cidr_bytes);
if (node->cidr)
ip[cidr_bytes - 1U] &= ~0U << (-node->cidr % 8U);
*cidr = node->cidr;
return node->bitlen == 32 ? AF_INET : AF_INET6;
}
/* Returns a strong reference to a peer */
struct wg_peer *wg_allowedips_lookup_dst(struct allowedips *table,
struct sk_buff *skb)
{
if (skb->protocol == htons(ETH_P_IP))
return lookup(table->root4, 32, &ip_hdr(skb)->daddr);
else if (skb->protocol == htons(ETH_P_IPV6))
return lookup(table->root6, 128, &ipv6_hdr(skb)->daddr);
return NULL;
}
/* Returns a strong reference to a peer */
struct wg_peer *wg_allowedips_lookup_src(struct allowedips *table,
struct sk_buff *skb)
{
if (skb->protocol == htons(ETH_P_IP))
return lookup(table->root4, 32, &ip_hdr(skb)->saddr);
else if (skb->protocol == htons(ETH_P_IPV6))
return lookup(table->root6, 128, &ipv6_hdr(skb)->saddr);
return NULL;
}
int __init wg_allowedips_slab_init(void)
{
node_cache = KMEM_CACHE(allowedips_node, 0);
return node_cache ? 0 : -ENOMEM;
}
void wg_allowedips_slab_uninit(void)
{
rcu_barrier();
kmem_cache_destroy(node_cache);
}
#include "selftest/allowedips.c"