openwrt/target/linux/generic/backport-5.4/080-wireguard-0104-wireguard-queueing-preserve-flow-hash-across-packet-.patch
Jason A. Donenfeld c0cb86e1d5 kernel: 5.4: import wireguard backport
Rather than using the clunky, old, slower wireguard-linux-compat out of
tree module, this commit does a patch-by-patch backport of upstream's
wireguard to 5.4. This specific backport is in widespread use, being
part of SUSE's enterprise kernel, Oracle's enterprise kernel, Google's
Android kernel, Gentoo's distro kernel, and probably more I've forgotten
about. It's definately the "more proper" way of adding wireguard to a
kernel than the ugly compat.h hell of the wireguard-linux-compat repo.
And most importantly for OpenWRT, it allows using the same module
configuration code for 5.10 as for 5.4, with no need for bifurcation.

These patches are from the backport tree which is maintained in the
open here: https://git.zx2c4.com/wireguard-linux/log/?h=backport-5.4.y
I'll be sending PRs to update this as needed.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
(cherry picked from commit 3888fa7880)
(cherry picked from commit d540725871)
(cherry picked from commit 196f3d586f)
(cherry picked from commit 3500fd7938)
(cherry picked from commit 23b801d3ba)
(cherry picked from commit 0c0cb97da7)
(cherry picked from commit 2a27f6f90a)
Signed-off-by: Ilya Lipnitskiy <ilya.lipnitskiy@gmail.com>
2021-04-10 14:21:32 +02:00

117 lines
4.3 KiB
Diff

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
Date: Tue, 19 May 2020 22:49:29 -0600
Subject: [PATCH] wireguard: queueing: preserve flow hash across packet
scrubbing
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
commit c78a0b4a78839d572d8a80f6a62221c0d7843135 upstream.
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: e7096c131e51 ("net: WireGuard secure network tunnel")
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---
drivers/net/wireguard/messages.h | 2 +-
drivers/net/wireguard/queueing.h | 10 +++++++++-
drivers/net/wireguard/receive.c | 2 +-
drivers/net/wireguard/send.c | 7 ++++++-
4 files changed, 17 insertions(+), 4 deletions(-)
--- a/drivers/net/wireguard/messages.h
+++ b/drivers/net/wireguard/messages.h
@@ -32,7 +32,7 @@ enum cookie_values {
};
enum counter_values {
- COUNTER_BITS_TOTAL = 2048,
+ COUNTER_BITS_TOTAL = 8192,
COUNTER_REDUNDANT_BITS = BITS_PER_LONG,
COUNTER_WINDOW_SIZE = COUNTER_BITS_TOTAL - COUNTER_REDUNDANT_BITS
};
--- a/drivers/net/wireguard/queueing.h
+++ b/drivers/net/wireguard/queueing.h
@@ -87,12 +87,20 @@ static inline bool wg_check_packet_proto
return real_protocol && skb->protocol == real_protocol;
}
-static inline void wg_reset_packet(struct sk_buff *skb)
+static inline void wg_reset_packet(struct sk_buff *skb, bool encapsulating)
{
+ u8 l4_hash = skb->l4_hash;
+ u8 sw_hash = skb->sw_hash;
+ u32 hash = skb->hash;
skb_scrub_packet(skb, true);
memset(&skb->headers_start, 0,
offsetof(struct sk_buff, headers_end) -
offsetof(struct sk_buff, headers_start));
+ if (encapsulating) {
+ skb->l4_hash = l4_hash;
+ skb->sw_hash = sw_hash;
+ skb->hash = hash;
+ }
skb->queue_mapping = 0;
skb->nohdr = 0;
skb->peeked = 0;
--- a/drivers/net/wireguard/receive.c
+++ b/drivers/net/wireguard/receive.c
@@ -484,7 +484,7 @@ int wg_packet_rx_poll(struct napi_struct
if (unlikely(wg_socket_endpoint_from_skb(&endpoint, skb)))
goto next;
- wg_reset_packet(skb);
+ wg_reset_packet(skb, false);
wg_packet_consume_data_done(peer, skb, &endpoint);
free = false;
--- a/drivers/net/wireguard/send.c
+++ b/drivers/net/wireguard/send.c
@@ -167,6 +167,11 @@ static bool encrypt_packet(struct sk_buf
struct sk_buff *trailer;
int num_frags;
+ /* Force hash calculation before encryption so that flow analysis is
+ * consistent over the inner packet.
+ */
+ skb_get_hash(skb);
+
/* Calculate lengths. */
padding_len = calculate_skb_padding(skb);
trailer_len = padding_len + noise_encrypted_len(0);
@@ -295,7 +300,7 @@ void wg_packet_encrypt_worker(struct wor
skb_list_walk_safe(first, skb, next) {
if (likely(encrypt_packet(skb,
PACKET_CB(first)->keypair))) {
- wg_reset_packet(skb);
+ wg_reset_packet(skb, true);
} else {
state = PACKET_STATE_DEAD;
break;