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62 lines
2.4 KiB
Diff
62 lines
2.4 KiB
Diff
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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: "Jason A. Donenfeld" <Jason@zx2c4.com>
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Date: Tue, 19 May 2020 22:49:28 -0600
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Subject: [PATCH] wireguard: noise: read preshared key while taking lock
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commit bc67d371256f5c47d824e2eec51e46c8d62d022e upstream.
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Prior we read the preshared key after dropping the handshake lock, which
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isn't an actual crypto issue if it races, but it's still not quite
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correct. So copy that part of the state into a temporary like we do with
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the rest of the handshake state variables. Then we can release the lock,
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operate on the temporary, and zero it out at the end of the function. In
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performance tests, the impact of this was entirely unnoticable, probably
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because those bytes are coming from the same cacheline as other things
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that are being copied out in the same manner.
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Reported-by: Matt Dunwoodie <ncon@noconroy.net>
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Fixes: e7096c131e51 ("net: WireGuard secure network tunnel")
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Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
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Signed-off-by: David S. Miller <davem@davemloft.net>
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Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
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---
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drivers/net/wireguard/noise.c | 6 +++++-
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1 file changed, 5 insertions(+), 1 deletion(-)
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--- a/drivers/net/wireguard/noise.c
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+++ b/drivers/net/wireguard/noise.c
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@@ -715,6 +715,7 @@ wg_noise_handshake_consume_response(stru
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u8 e[NOISE_PUBLIC_KEY_LEN];
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u8 ephemeral_private[NOISE_PUBLIC_KEY_LEN];
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u8 static_private[NOISE_PUBLIC_KEY_LEN];
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+ u8 preshared_key[NOISE_SYMMETRIC_KEY_LEN];
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down_read(&wg->static_identity.lock);
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@@ -733,6 +734,8 @@ wg_noise_handshake_consume_response(stru
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memcpy(chaining_key, handshake->chaining_key, NOISE_HASH_LEN);
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memcpy(ephemeral_private, handshake->ephemeral_private,
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NOISE_PUBLIC_KEY_LEN);
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+ memcpy(preshared_key, handshake->preshared_key,
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+ NOISE_SYMMETRIC_KEY_LEN);
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up_read(&handshake->lock);
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if (state != HANDSHAKE_CREATED_INITIATION)
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@@ -750,7 +753,7 @@ wg_noise_handshake_consume_response(stru
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goto fail;
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/* psk */
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- mix_psk(chaining_key, hash, key, handshake->preshared_key);
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+ mix_psk(chaining_key, hash, key, preshared_key);
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/* {} */
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if (!message_decrypt(NULL, src->encrypted_nothing,
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@@ -783,6 +786,7 @@ out:
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memzero_explicit(chaining_key, NOISE_HASH_LEN);
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memzero_explicit(ephemeral_private, NOISE_PUBLIC_KEY_LEN);
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memzero_explicit(static_private, NOISE_PUBLIC_KEY_LEN);
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+ memzero_explicit(preshared_key, NOISE_SYMMETRIC_KEY_LEN);
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up_read(&wg->static_identity.lock);
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return ret_peer;
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}
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