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authorJason A. Donenfeld <Jason@zx2c4.com>2020-05-20 07:49:28 +0300
committerDavid S. Miller <davem@davemloft.net>2020-05-21 06:55:09 +0300
commitbc67d371256f5c47d824e2eec51e46c8d62d022e (patch)
treebc1e1c7b59120be31ea92b720df058c9b3fd9ead /drivers/net/wireguard
parentee3c1aa3f34b7842c1557cfe5d8c3f7b8c692de8 (diff)
downloadlinux-bc67d371256f5c47d824e2eec51e46c8d62d022e.tar.xz
wireguard: noise: read preshared key while taking lock
Prior we read the preshared key after dropping the handshake lock, which isn't an actual crypto issue if it races, but it's still not quite correct. So copy that part of the state into a temporary like we do with the rest of the handshake state variables. Then we can release the lock, operate on the temporary, and zero it out at the end of the function. In performance tests, the impact of this was entirely unnoticable, probably because those bytes are coming from the same cacheline as other things that are being copied out in the same manner. Reported-by: Matt Dunwoodie <ncon@noconroy.net> 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>
Diffstat (limited to 'drivers/net/wireguard')
-rw-r--r--drivers/net/wireguard/noise.c6
1 files changed, 5 insertions, 1 deletions
diff --git a/drivers/net/wireguard/noise.c b/drivers/net/wireguard/noise.c
index 708dc61c974f..07eb438a6dee 100644
--- a/drivers/net/wireguard/noise.c
+++ b/drivers/net/wireguard/noise.c
@@ -715,6 +715,7 @@ wg_noise_handshake_consume_response(struct message_handshake_response *src,
u8 e[NOISE_PUBLIC_KEY_LEN];
u8 ephemeral_private[NOISE_PUBLIC_KEY_LEN];
u8 static_private[NOISE_PUBLIC_KEY_LEN];
+ u8 preshared_key[NOISE_SYMMETRIC_KEY_LEN];
down_read(&wg->static_identity.lock);
@@ -733,6 +734,8 @@ wg_noise_handshake_consume_response(struct message_handshake_response *src,
memcpy(chaining_key, handshake->chaining_key, NOISE_HASH_LEN);
memcpy(ephemeral_private, handshake->ephemeral_private,
NOISE_PUBLIC_KEY_LEN);
+ memcpy(preshared_key, handshake->preshared_key,
+ NOISE_SYMMETRIC_KEY_LEN);
up_read(&handshake->lock);
if (state != HANDSHAKE_CREATED_INITIATION)
@@ -750,7 +753,7 @@ wg_noise_handshake_consume_response(struct message_handshake_response *src,
goto fail;
/* psk */
- mix_psk(chaining_key, hash, key, handshake->preshared_key);
+ mix_psk(chaining_key, hash, key, preshared_key);
/* {} */
if (!message_decrypt(NULL, src->encrypted_nothing,
@@ -783,6 +786,7 @@ out:
memzero_explicit(chaining_key, NOISE_HASH_LEN);
memzero_explicit(ephemeral_private, NOISE_PUBLIC_KEY_LEN);
memzero_explicit(static_private, NOISE_PUBLIC_KEY_LEN);
+ memzero_explicit(preshared_key, NOISE_SYMMETRIC_KEY_LEN);
up_read(&wg->static_identity.lock);
return ret_peer;
}