> -----Original Message-----
> From: netdev-ow...@vger.kernel.org <netdev-ow...@vger.kernel.org> On
> Behalf Of Sabrina Dubroca
> Sent: Wednesday, September 5, 2018 6:52 PM
> To: netdev@vger.kernel.org
> Cc: Sabrina Dubroca <s...@queasysnail.net>; Boris Pismenny
> <bor...@mellanox.com>; Ilya Lesokhin <il...@mellanox.com>; Aviad
> Yehezkel <avia...@mellanox.com>; Dave Watson <davejwat...@fb.com>
> Subject: [PATCH net 3/3] tls: zero the crypto information from tls_context
> before freeing
>
> This contains key material in crypto_send_aes_gcm_128 and
> crypto_recv_aes_gcm_128.
>
> Fixes: 3c4d7559159b ("tls: kernel TLS support")
> Signed-off-by: Sabrina Dubroca <s...@queasysnail.net>
> ---
> include/net/tls.h | 1 +
> net/tls/tls_main.c | 14 ++++++++++++--
> 2 files changed, 13 insertions(+), 2 deletions(-)
>
> diff --git a/include/net/tls.h b/include/net/tls.h index
> d5c683e8bb22..2010d23112f9 100644
> --- a/include/net/tls.h
> +++ b/include/net/tls.h
> @@ -180,6 +180,7 @@ struct tls_context {
> struct tls_crypto_info crypto_recv;
> struct tls12_crypto_info_aes_gcm_128
> crypto_recv_aes_gcm_128;
> };
> + char tls_crypto_ctx_end[0];
This makes the key zeroization dependent upon the position of unions in
structure.
Can you zeroise the crypto_send, crypto_recv separately using two
memzero_explicit calls?
>
> struct list_head list;
> struct net_device *netdev;
> diff --git a/net/tls/tls_main.c b/net/tls/tls_main.c index
> 0d432d025471..d3a57c0b2182 100644
> --- a/net/tls/tls_main.c
> +++ b/net/tls/tls_main.c
> @@ -241,6 +241,16 @@ static void tls_write_space(struct sock *sk)
> ctx->sk_write_space(sk);
> }
>
> +static void tls_ctx_free(struct tls_context *ctx) {
> + if (!ctx)
> + return;
> +
> + memzero_explicit(&ctx->crypto_send,
> + offsetof(struct tls_context, tls_crypto_ctx_end));
> + kfree(ctx);
> +}
> +
> static void tls_sk_proto_close(struct sock *sk, long timeout) {
> struct tls_context *ctx = tls_get_ctx(sk); @@ -294,7 +304,7 @@
> static void tls_sk_proto_close(struct sock *sk, long timeout) #else
> {
> #endif
> - kfree(ctx);
> + tls_ctx_free(ctx);
> ctx = NULL;
> }
>
> @@ -305,7 +315,7 @@ static void tls_sk_proto_close(struct sock *sk, long
> timeout)
> * for sk->sk_prot->unhash [tls_hw_unhash]
> */
> if (free_ctx)
> - kfree(ctx);
> + tls_ctx_free(ctx);
> }
>
> static int do_tls_getsockopt_tx(struct sock *sk, char __user *optval,
> --
> 2.18.0
