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.

Introduce union tls_crypto_context, and replace the two identical
unions directly embedded in struct tls_context with it. We can then
use this union to clean up the memory in the new tls_ctx_free()
function.

Fixes: 3c4d7559159b ("tls: kernel TLS support")
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 15 insertions, 5 deletions

diff --git a/net/tls/tls_main.c b/net/tls/tls_main.c
index 180b6640e531..737b3865be1b 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, sizeof(ctx->crypto_send));
+        memzero_explicit(&ctx->crypto_recv, sizeof(ctx->crypto_recv));
+        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 @@ skip_tx_cleanup:
          * 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,
@@ -330,7 +340,7 @@ static int do_tls_getsockopt_tx(struct sock *sk, char __user *optval,
         }
 
         /* get user crypto info */
-        crypto_info = &ctx->crypto_send;
+        crypto_info = &ctx->crypto_send.info;
 
         if (!TLS_CRYPTO_INFO_READY(crypto_info)) {
                 rc = -EBUSY;
@@ -417,9 +427,9 @@ static int do_tls_setsockopt_conf(struct sock *sk, char __user *optval,
         }
 
         if (tx)
-                crypto_info = &ctx->crypto_send;
+                crypto_info = &ctx->crypto_send.info;
         else
-                crypto_info = &ctx->crypto_recv;
+                crypto_info = &ctx->crypto_recv.info;
 
         /* Currently we don't support set crypto info more than one time */
         if (TLS_CRYPTO_INFO_READY(crypto_info)) {