diff options
| author | Eric Dumazet <edumazet@google.com> | 2020-07-01 02:41:01 +0300 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2020-07-01 04:14:38 +0300 |
| commit | 6a2febec338df7e7699a52d00b2e1207dcf65b28 (patch) | |
| tree | 778dc294a8c0a7f9ea767ac01539b3c2e58ba490 /net | |
| parent | 28541f3d324f6de1e545e2875283b6cef95c5d36 (diff) | |
| download | linux-6a2febec338df7e7699a52d00b2e1207dcf65b28.tar.xz | |
tcp: md5: add missing memory barriers in tcp_md5_do_add()/tcp_md5_hash_key()
MD5 keys are read with RCU protection, and tcp_md5_do_add()
might update in-place a prior key.
Normally, typical RCU updates would allocate a new piece
of memory. In this case only key->key and key->keylen might
be updated, and we do not care if an incoming packet could
see the old key, the new one, or some intermediate value,
since changing the key on a live flow is known to be problematic
anyway.
We only want to make sure that in the case key->keylen
is changed, cpus in tcp_md5_hash_key() wont try to use
uninitialized data, or crash because key->keylen was
read twice to feed sg_init_one() and ahash_request_set_crypt()
Fixes: 9ea88a153001 ("tcp: md5: check md5 signature without socket lock")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
| -rw-r--r-- | net/ipv4/tcp.c | 7 | ||||
| -rw-r--r-- | net/ipv4/tcp_ipv4.c | 3 |
2 files changed, 8 insertions, 2 deletions
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 810cc164f795..f11166045324 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -4033,10 +4033,13 @@ EXPORT_SYMBOL(tcp_md5_hash_skb_data); int tcp_md5_hash_key(struct tcp_md5sig_pool *hp, const struct tcp_md5sig_key *key) { + u8 keylen = key->keylen; struct scatterlist sg; - sg_init_one(&sg, key->key, key->keylen); - ahash_request_set_crypt(hp->md5_req, &sg, NULL, key->keylen); + smp_rmb(); /* paired with smp_wmb() in tcp_md5_do_add() */ + + sg_init_one(&sg, key->key, keylen); + ahash_request_set_crypt(hp->md5_req, &sg, NULL, keylen); return crypto_ahash_update(hp->md5_req); } EXPORT_SYMBOL(tcp_md5_hash_key); diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index ad6435ba6d72..99916fcc15ca 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -1113,6 +1113,9 @@ int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr, if (key) { /* Pre-existing entry - just update that one. */ memcpy(key->key, newkey, newkeylen); + + smp_wmb(); /* pairs with smp_rmb() in tcp_md5_hash_key() */ + key->keylen = newkeylen; return 0; } |