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c78a0b4a78
It's important that we clear most header fields during encapsulation and
decapsulation, because the packet is substantially changed, and we don't
want any info leak or logic bug due to an accidental correlation. But,
for encapsulation, it's wrong to clear skb->hash, since it's used by
fq_codel and flow dissection in general. Without it, classification does
not proceed as usual. This change might make it easier to estimate the
number of innerflows by examining clustering of out of order packets,
but this shouldn't open up anything that can't already be inferred
otherwise (e.g. syn packet size inference), and fq_codel can be disabled
anyway.
Furthermore, it might be the case that the hash isn't used or queried at
all until after wireguard transmits the encrypted UDP packet, which
means skb->hash might still be zero at this point, and thus no hash
taken over the inner packet data. In order to address this situation, we
force a calculation of skb->hash before encrypting packet data.
Of course this means that fq_codel might transmit packets slightly more
out of order than usual. Toke did some testing on beefy machines with
high quantities of parallel flows and found that increasing the
reply-attack counter to 8192 takes care of the most pathological cases
pretty well.
Reported-by: Dave Taht <dave.taht@gmail.com>
Reviewed-and-tested-by: Toke Høiland-Jørgensen <toke@toke.dk>
Fixes: e7096c131e ("net: WireGuard secure network tunnel")
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
129 lines
3.3 KiB
C
129 lines
3.3 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Copyright (C) 2015-2019 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
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*/
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#ifndef _WG_MESSAGES_H
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#define _WG_MESSAGES_H
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#include <crypto/curve25519.h>
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#include <crypto/chacha20poly1305.h>
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#include <crypto/blake2s.h>
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#include <linux/kernel.h>
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#include <linux/param.h>
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#include <linux/skbuff.h>
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enum noise_lengths {
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NOISE_PUBLIC_KEY_LEN = CURVE25519_KEY_SIZE,
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NOISE_SYMMETRIC_KEY_LEN = CHACHA20POLY1305_KEY_SIZE,
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NOISE_TIMESTAMP_LEN = sizeof(u64) + sizeof(u32),
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NOISE_AUTHTAG_LEN = CHACHA20POLY1305_AUTHTAG_SIZE,
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NOISE_HASH_LEN = BLAKE2S_HASH_SIZE
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};
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#define noise_encrypted_len(plain_len) ((plain_len) + NOISE_AUTHTAG_LEN)
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enum cookie_values {
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COOKIE_SECRET_MAX_AGE = 2 * 60,
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COOKIE_SECRET_LATENCY = 5,
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COOKIE_NONCE_LEN = XCHACHA20POLY1305_NONCE_SIZE,
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COOKIE_LEN = 16
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};
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enum counter_values {
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COUNTER_BITS_TOTAL = 8192,
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COUNTER_REDUNDANT_BITS = BITS_PER_LONG,
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COUNTER_WINDOW_SIZE = COUNTER_BITS_TOTAL - COUNTER_REDUNDANT_BITS
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};
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enum limits {
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REKEY_AFTER_MESSAGES = 1ULL << 60,
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REJECT_AFTER_MESSAGES = U64_MAX - COUNTER_WINDOW_SIZE - 1,
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REKEY_TIMEOUT = 5,
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REKEY_TIMEOUT_JITTER_MAX_JIFFIES = HZ / 3,
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REKEY_AFTER_TIME = 120,
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REJECT_AFTER_TIME = 180,
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INITIATIONS_PER_SECOND = 50,
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MAX_PEERS_PER_DEVICE = 1U << 20,
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KEEPALIVE_TIMEOUT = 10,
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MAX_TIMER_HANDSHAKES = 90 / REKEY_TIMEOUT,
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MAX_QUEUED_INCOMING_HANDSHAKES = 4096, /* TODO: replace this with DQL */
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MAX_STAGED_PACKETS = 128,
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MAX_QUEUED_PACKETS = 1024 /* TODO: replace this with DQL */
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};
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enum message_type {
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MESSAGE_INVALID = 0,
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MESSAGE_HANDSHAKE_INITIATION = 1,
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MESSAGE_HANDSHAKE_RESPONSE = 2,
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MESSAGE_HANDSHAKE_COOKIE = 3,
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MESSAGE_DATA = 4
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};
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struct message_header {
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/* The actual layout of this that we want is:
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* u8 type
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* u8 reserved_zero[3]
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*
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* But it turns out that by encoding this as little endian,
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* we achieve the same thing, and it makes checking faster.
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*/
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__le32 type;
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};
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struct message_macs {
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u8 mac1[COOKIE_LEN];
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u8 mac2[COOKIE_LEN];
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};
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struct message_handshake_initiation {
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struct message_header header;
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__le32 sender_index;
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u8 unencrypted_ephemeral[NOISE_PUBLIC_KEY_LEN];
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u8 encrypted_static[noise_encrypted_len(NOISE_PUBLIC_KEY_LEN)];
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u8 encrypted_timestamp[noise_encrypted_len(NOISE_TIMESTAMP_LEN)];
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struct message_macs macs;
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};
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struct message_handshake_response {
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struct message_header header;
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__le32 sender_index;
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__le32 receiver_index;
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u8 unencrypted_ephemeral[NOISE_PUBLIC_KEY_LEN];
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u8 encrypted_nothing[noise_encrypted_len(0)];
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struct message_macs macs;
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};
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struct message_handshake_cookie {
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struct message_header header;
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__le32 receiver_index;
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u8 nonce[COOKIE_NONCE_LEN];
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u8 encrypted_cookie[noise_encrypted_len(COOKIE_LEN)];
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};
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struct message_data {
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struct message_header header;
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__le32 key_idx;
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__le64 counter;
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u8 encrypted_data[];
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};
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#define message_data_len(plain_len) \
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(noise_encrypted_len(plain_len) + sizeof(struct message_data))
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enum message_alignments {
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MESSAGE_PADDING_MULTIPLE = 16,
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MESSAGE_MINIMUM_LENGTH = message_data_len(0)
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};
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#define SKB_HEADER_LEN \
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(max(sizeof(struct iphdr), sizeof(struct ipv6hdr)) + \
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sizeof(struct udphdr) + NET_SKB_PAD)
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#define DATA_PACKET_HEAD_ROOM \
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ALIGN(sizeof(struct message_data) + SKB_HEADER_LEN, 4)
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enum { HANDSHAKE_DSCP = 0x88 /* AF41, plus 00 ECN */ };
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#endif /* _WG_MESSAGES_H */
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