diff options
Diffstat (limited to 'drivers/net/wireguard/symmetric.c')
| -rw-r--r-- | drivers/net/wireguard/symmetric.c | 173 |
1 files changed, 173 insertions, 0 deletions
diff --git a/drivers/net/wireguard/symmetric.c b/drivers/net/wireguard/symmetric.c new file mode 100644 index 000000000000..be81ba5c882e --- /dev/null +++ b/drivers/net/wireguard/symmetric.c @@ -0,0 +1,173 @@ +// 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_encrypt_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) { + enum packet_state state = PACKET_STATE_CRYPTED; + + 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); + } +} + +void wg_packet_decrypt_worker(struct work_struct *work) +{ + struct crypt_queue *queue = container_of(work, struct multicore_worker, + work)->ptr; + struct sk_buff *skb; + + while ((skb = ptr_ring_consume_bh(&queue->ring)) != NULL) { + enum packet_state state = likely(decrypt_packet(skb, + &PACKET_CB(skb)->keypair->receiving)) ? + PACKET_STATE_CRYPTED : PACKET_STATE_DEAD; + wg_queue_enqueue_per_peer_napi(skb, state); + } +} + |