From f19008e676366c44e9241af57f331b6c6edf9552 Mon Sep 17 00:00:00 2001 From: Jason Baron Date: Mon, 10 Aug 2020 13:38:39 -0400 Subject: tcp: correct read of TFO keys on big endian systems When TFO keys are read back on big endian systems either via the global sysctl interface or via getsockopt() using TCP_FASTOPEN_KEY, the values don't match what was written. For example, on s390x: # echo "1-2-3-4" > /proc/sys/net/ipv4/tcp_fastopen_key # cat /proc/sys/net/ipv4/tcp_fastopen_key 02000000-01000000-04000000-03000000 Instead of: # cat /proc/sys/net/ipv4/tcp_fastopen_key 00000001-00000002-00000003-00000004 Fix this by converting to the correct endianness on read. This was reported by Colin Ian King when running the 'tcp_fastopen_backup_key' net selftest on s390x, which depends on the read value matching what was written. I've confirmed that the test now passes on big and little endian systems. Signed-off-by: Jason Baron Fixes: 438ac88009bc ("net: fastopen: robustness and endianness fixes for SipHash") Cc: Ard Biesheuvel Cc: Eric Dumazet Reported-and-tested-by: Colin Ian King Signed-off-by: David S. Miller --- net/ipv4/tcp.c | 16 ++++------------ 1 file changed, 4 insertions(+), 12 deletions(-) (limited to 'net/ipv4/tcp.c') diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index c06d2bfd2ec4..31f3b858db81 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -3685,22 +3685,14 @@ static int do_tcp_getsockopt(struct sock *sk, int level, return 0; case TCP_FASTOPEN_KEY: { - __u8 key[TCP_FASTOPEN_KEY_BUF_LENGTH]; - struct tcp_fastopen_context *ctx; - unsigned int key_len = 0; + u64 key[TCP_FASTOPEN_KEY_BUF_LENGTH / sizeof(u64)]; + unsigned int key_len; if (get_user(len, optlen)) return -EFAULT; - rcu_read_lock(); - ctx = rcu_dereference(icsk->icsk_accept_queue.fastopenq.ctx); - if (ctx) { - key_len = tcp_fastopen_context_len(ctx) * - TCP_FASTOPEN_KEY_LENGTH; - memcpy(&key[0], &ctx->key[0], key_len); - } - rcu_read_unlock(); - + key_len = tcp_fastopen_get_cipher(net, icsk, key) * + TCP_FASTOPEN_KEY_LENGTH; len = min_t(unsigned int, len, key_len); if (put_user(len, optlen)) return -EFAULT; -- cgit v1.2.3