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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2015-2012 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
*/
#include "queueing.h"
#include "messages.h"
#include "timers.h"
static unsigned int calculate_skb_padding(struct sk_buff *skb)
{
unsigned int padded_size, last_unit = skb->len;
if (unlikely(!PACKET_CB(skb)->mtu))
return ALIGN(last_unit, MESSAGE_PADDING_MULTIPLE) - last_unit;
/* We do this modulo business with the MTU, just in case the networking
* layer gives us a packet that's bigger than the MTU. In that case, we
* wouldn't want the final subtraction to overflow in the case of the
* padded_size being clamped. Fortunately, that's very rarely the case,
* so we optimize for that not happening.
*/
if (unlikely(last_unit > PACKET_CB(skb)->mtu))
last_unit %= PACKET_CB(skb)->mtu;
padded_size = min(PACKET_CB(skb)->mtu,
ALIGN(last_unit, MESSAGE_PADDING_MULTIPLE));
return padded_size - last_unit;
}
static bool encrypt_packet(struct sk_buff *skb, struct noise_keypair *keypair)
{
unsigned int padding_len, plaintext_len, trailer_len;
struct scatterlist sg[MAX_SKB_FRAGS + 8];
struct message_data *header;
struct sk_buff *trailer;
int num_frags;
/* Calculate lengths. */
padding_len = calculate_skb_padding(skb);
trailer_len = padding_len + noise_encrypted_len(0);
plaintext_len = skb->len + padding_len;
/* Expand data section to have room for padding and auth tag. */
num_frags = skb_cow_data(skb, trailer_len, &trailer);
if (unlikely(num_frags < 0 || num_frags > ARRAY_SIZE(sg)))
return false;
/* Set the padding to zeros, and make sure it and the auth tag are part
* of the skb.
*/
memset(skb_tail_pointer(trailer), 0, padding_len);
/* Expand head section to have room for our header and the network
* stack's headers.
*/
if (unlikely(skb_cow_head(skb, DATA_PACKET_HEAD_ROOM) < 0))
return false;
/* Finalize checksum calculation for the inner packet, if required. */
if (unlikely(skb->ip_summed == CHECKSUM_PARTIAL &&
skb_checksum_help(skb)))
return false;
/* Only after checksumming can we safely add on the padding at the end
* and the header.
*/
skb_set_inner_network_header(skb, 0);
header = (struct message_data *)skb_push(skb, sizeof(*header));
header->header.type = cpu_to_le32(MESSAGE_DATA);
header->key_idx = keypair->remote_index;
header->counter = cpu_to_le64(PACKET_CB(skb)->nonce);
pskb_put(skb, trailer, trailer_len);
/* Now we can encrypt the scattergather segments */
sg_init_table(sg, num_frags);
if (skb_to_sgvec(skb, sg, sizeof(struct message_data),
noise_encrypted_len(plaintext_len)) <= 0)
return false;
return chacha20poly1305_encrypt_sg_inplace(sg, plaintext_len, NULL, 0,
PACKET_CB(skb)->nonce,
keypair->sending.key);
}
static bool decrypt_packet(struct sk_buff *skb, struct noise_symmetric_key *key)
{
struct scatterlist sg[MAX_SKB_FRAGS + 8];
struct sk_buff *trailer;
unsigned int offset;
int num_frags;
if (unlikely(!key))
return false;
if (unlikely(!READ_ONCE(key->is_valid) ||
wg_birthdate_has_expired(key->birthdate, REJECT_AFTER_TIME) ||
key->counter.receive.counter >= REJECT_AFTER_MESSAGES)) {
WRITE_ONCE(key->is_valid, false);
return false;
}
PACKET_CB(skb)->nonce =
le64_to_cpu(((struct message_data *)skb->data)->counter);
/* We ensure that the network header is part of the packet before we
* call skb_cow_data, so that there's no chance that data is removed
* from the skb, so that later we can extract the original endpoint.
*/
offset = skb->data - skb_network_header(skb);
skb_push(skb, offset);
num_frags = skb_cow_data(skb, 0, &trailer);
offset += sizeof(struct message_data);
skb_pull(skb, offset);
if (unlikely(num_frags < 0 || num_frags > ARRAY_SIZE(sg)))
return false;
sg_init_table(sg, num_frags);
if (skb_to_sgvec(skb, sg, 0, skb->len) <= 0)
return false;
if (!chacha20poly1305_decrypt_sg_inplace(sg, skb->len, NULL, 0,
PACKET_CB(skb)->nonce,
key->key))
return false;
/* Another ugly situation of pushing and pulling the header so as to
* keep endpoint information intact.
*/
skb_push(skb, offset);
if (pskb_trim(skb, skb->len - noise_encrypted_len(0)))
return false;
skb_pull(skb, offset);
return true;
}
void wg_packet_crypt_worker(struct work_struct *work)
{
struct crypt_queue *queue = container_of(work, struct multicore_worker,
work)->ptr;
struct sk_buff *first, *skb, *next;
while ((first = ptr_ring_consume_bh(&queue->ring)) != NULL) {
switch (atomic_read_acquire(&PACKET_CB(first)->state)) {
case PACKET_STATE_NOT_ENCRYPTED: {
enum packet_state state = PACKET_STATE_ENCRYPTED;
skb_list_walk_safe(first, skb, next) {
if (likely(encrypt_packet(skb,
PACKET_CB(first)->keypair))) {
wg_reset_packet(skb);
} else {
state = PACKET_STATE_DEAD;
break;
}
}
wg_queue_enqueue_per_peer(&PACKET_PEER(first)->tx_queue,
first, state);
break;
}
case PACKET_STATE_NOT_DECRYPTED: {
enum packet_state state = likely(decrypt_packet(first,
&PACKET_CB(first)->keypair->receiving)) ?
PACKET_STATE_DECRYPTED : PACKET_STATE_DEAD;
wg_queue_enqueue_per_peer_napi(first, state);
break;
}
}
}
}
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