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196f3d586f
5.4.102 backported a lot of stuff that our WireGuard backport already did, in addition to other patches we had, so those patches were removed from that part of the series. In the process other patches were refreshed or reworked to account for upstream changes. This commit involved `update_kernel.sh -v -u 5.4`. Cc: John Audia <graysky@archlinux.us> Cc: David Bauer <mail@david-bauer.net> Cc: Petr Štetiar <ynezz@true.cz> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
63 lines
2.5 KiB
Diff
63 lines
2.5 KiB
Diff
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: Wed, 9 Sep 2020 13:58:15 +0200
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Subject: [PATCH] wireguard: peerlookup: take lock before checking hash in
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replace operation
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commit 6147f7b1e90ff09bd52afc8b9206a7fcd133daf7 upstream.
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Eric's suggested fix for the previous commit's mentioned race condition
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was to simply take the table->lock in wg_index_hashtable_replace(). The
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table->lock of the hash table is supposed to protect the bucket heads,
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not the entires, but actually, since all the mutator functions are
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already taking it, it makes sense to take it too for the test to
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hlist_unhashed, as a defense in depth measure, so that it no longer
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races with deletions, regardless of what other locks are protecting
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individual entries. This is sensible from a performance perspective
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because, as Eric pointed out, the case of being unhashed is already the
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unlikely case, so this won't add common contention. And comparing
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instructions, this basically doesn't make much of a difference other
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than pushing and popping %r13, used by the new `bool ret`. More
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generally, I like the idea of locking consistency across table mutator
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functions, and this might let me rest slightly easier at night.
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Suggested-by: Eric Dumazet <edumazet@google.com>
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Link: https://lore.kernel.org/wireguard/20200908145911.4090480-1-edumazet@google.com/
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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/peerlookup.c | 11 ++++++++---
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1 file changed, 8 insertions(+), 3 deletions(-)
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--- a/drivers/net/wireguard/peerlookup.c
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+++ b/drivers/net/wireguard/peerlookup.c
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@@ -167,9 +167,13 @@ bool wg_index_hashtable_replace(struct i
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struct index_hashtable_entry *old,
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struct index_hashtable_entry *new)
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{
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- if (unlikely(hlist_unhashed(&old->index_hash)))
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- return false;
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+ bool ret;
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+
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spin_lock_bh(&table->lock);
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+ ret = !hlist_unhashed(&old->index_hash);
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+ if (unlikely(!ret))
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+ goto out;
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+
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new->index = old->index;
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hlist_replace_rcu(&old->index_hash, &new->index_hash);
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@@ -180,8 +184,9 @@ bool wg_index_hashtable_replace(struct i
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* simply gets dropped, which isn't terrible.
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*/
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INIT_HLIST_NODE(&old->index_hash);
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+out:
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spin_unlock_bh(&table->lock);
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- return true;
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+ return ret;
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}
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void wg_index_hashtable_remove(struct index_hashtable *table,
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