diff options
Diffstat (limited to 'drivers/net/wireguard/allowedips.c')
| -rw-r--r-- | drivers/net/wireguard/allowedips.c | 376 |
1 files changed, 376 insertions, 0 deletions
diff --git a/drivers/net/wireguard/allowedips.c b/drivers/net/wireguard/allowedips.c new file mode 100644 index 000000000000..121d9ea0f135 --- /dev/null +++ b/drivers/net/wireguard/allowedips.c @@ -0,0 +1,376 @@ +// 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 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); +} +#define CHOOSE_NODE(parent, key) \ + parent->bit[(key[parent->bit_at_a] >> parent->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 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); + kfree(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 void walk_remove_by_peer(struct allowedips_node __rcu **top, + struct wg_peer *peer, struct mutex *lock) +{ +#define REF(p) rcu_access_pointer(p) +#define DEREF(p) rcu_dereference_protected(*(p), lockdep_is_held(lock)) +#define PUSH(p) ({ \ + WARN_ON(IS_ENABLED(DEBUG) && len >= 128); \ + stack[len++] = p; \ + }) + + struct allowedips_node __rcu **stack[128], **nptr; + struct allowedips_node *node, *prev; + unsigned int len; + + if (unlikely(!peer || !REF(*top))) + return; + + for (prev = NULL, len = 0, PUSH(top); len > 0; prev = node) { + nptr = stack[len - 1]; + node = DEREF(nptr); + if (!node) { + --len; + continue; + } + if (!prev || REF(prev->bit[0]) == node || + REF(prev->bit[1]) == node) { + if (REF(node->bit[0])) + PUSH(&node->bit[0]); + else if (REF(node->bit[1])) + PUSH(&node->bit[1]); + } else if (REF(node->bit[0]) == prev) { + if (REF(node->bit[1])) + PUSH(&node->bit[1]); + } else { + if (rcu_dereference_protected(node->peer, + lockdep_is_held(lock)) == peer) { + RCU_INIT_POINTER(node->peer, NULL); + list_del_init(&node->peer_list); + if (!node->bit[0] || !node->bit[1]) { + rcu_assign_pointer(*nptr, DEREF( + &node->bit[!REF(node->bit[0])])); + kfree_rcu(node, rcu); + node = DEREF(nptr); + } + } + --len; + } + } + +#undef REF +#undef DEREF +#undef PUSH +} + +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(CHOOSE_NODE(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(CHOOSE_NODE(parent, key), + lockdep_is_held(lock)); + } + *rnode = parent; + return exact; +} + +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 = kzalloc(sizeof(*node), 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); + rcu_assign_pointer(*trie, 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 = kzalloc(sizeof(*newnode), 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 { + down = rcu_dereference_protected(CHOOSE_NODE(node, key), + lockdep_is_held(lock)); + if (!down) { + rcu_assign_pointer(CHOOSE_NODE(node, key), newnode); + return 0; + } + } + cidr = min(cidr, common_bits(down, key, bits)); + parent = node; + + if (newnode->cidr == cidr) { + rcu_assign_pointer(CHOOSE_NODE(newnode, down->bits), down); + if (!parent) + rcu_assign_pointer(*trie, newnode); + else + rcu_assign_pointer(CHOOSE_NODE(parent, newnode->bits), + newnode); + } else { + node = kzalloc(sizeof(*node), GFP_KERNEL); + if (unlikely(!node)) { + kfree(newnode); + return -ENOMEM; + } + INIT_LIST_HEAD(&node->peer_list); + copy_and_assign_cidr(node, newnode->bits, cidr, bits); + + rcu_assign_pointer(CHOOSE_NODE(node, down->bits), down); + rcu_assign_pointer(CHOOSE_NODE(node, newnode->bits), newnode); + if (!parent) + rcu_assign_pointer(*trie, node); + else + rcu_assign_pointer(CHOOSE_NODE(parent, node->bits), + 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) +{ + ++table->seq; + walk_remove_by_peer(&table->root4, peer, lock); + walk_remove_by_peer(&table->root6, peer, lock); +} + +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; +} + +#include "selftest/allowedips.c" |