[PATCH net-next] net: tls: Pass union tls_crypto_context pointer to memzero_explicit

[PATCH net-next] net: tls: Pass union tls_crypto_context pointer to memzero_explicit

[Simon Horman]

Pass union tls_crypto_context pointer, rather than struct
tls_crypto_info pointer, to memzero_explicit().

The address of the pointer is the same before and after.
But the new construct means that the size of the dereferenced pointer type
matches the size being zeroed. Which aids static analysis.

As reported by Smatch:

  .../tls_main.c:842 do_tls_setsockopt_conf() error: memzero_explicit() 'crypto_info' too small (4 vs 56)

No functional change intended.
Compile tested only.

Signed-off-by: Simon Horman <horms@kernel.org>
---
 net/tls/tls_main.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/net/tls/tls_main.c b/net/tls/tls_main.c
index 90b7f253d363..e712b2faeb81 100644
--- a/net/tls/tls_main.c
+++ b/net/tls/tls_main.c
@@ -616,6 +616,7 @@ static int do_tls_setsockopt_conf(struct sock *sk, sockptr_t optval,
 	struct tls_crypto_info *alt_crypto_info;
 	struct tls_context *ctx = tls_get_ctx(sk);
 	const struct tls_cipher_desc *cipher_desc;
+	union tls_crypto_context *crypto_ctx;
 	int rc = 0;
 	int conf;
 
@@ -623,13 +624,15 @@ static int do_tls_setsockopt_conf(struct sock *sk, sockptr_t optval,
 		return -EINVAL;
 
 	if (tx) {
-		crypto_info = &ctx->crypto_send.info;
+		crypto_ctx = &ctx->crypto_send;
 		alt_crypto_info = &ctx->crypto_recv.info;
 	} else {
-		crypto_info = &ctx->crypto_recv.info;
+		crypto_ctx = &ctx->crypto_recv;
 		alt_crypto_info = &ctx->crypto_send.info;
 	}
 
+	crypto_info = &crypto_ctx->info;
+
 	/* Currently we don't support set crypto info more than one time */
 	if (TLS_CRYPTO_INFO_READY(crypto_info))
 		return -EBUSY;
@@ -710,7 +713,7 @@ static int do_tls_setsockopt_conf(struct sock *sk, sockptr_t optval,
 	return 0;
 
 err_crypto_info:
-	memzero_explicit(crypto_info, sizeof(union tls_crypto_context));
+	memzero_explicit(crypto_ctx, sizeof(union tls_crypto_context));
 	return rc;
 }
 

Re: [PATCH net-next] net: tls: Pass union tls_crypto_context pointer to memzero_explicit

[Przemek Kitszel]

On 7/5/24 15:41, Simon Horman wrote:
> Pass union tls_crypto_context pointer, rather than struct
> tls_crypto_info pointer, to memzero_explicit().
> 
> The address of the pointer is the same before and after.
> But the new construct means that the size of the dereferenced pointer type
> matches the size being zeroed. Which aids static analysis.
> 
> As reported by Smatch:
> 
>    .../tls_main.c:842 do_tls_setsockopt_conf() error: memzero_explicit() 'crypto_info' too small (4 vs 56)
> 
> No functional change intended.
> Compile tested only.
> 
> Signed-off-by: Simon Horman <horms@kernel.org>

Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
one small nitpick only

> ---
>   net/tls/tls_main.c | 9 ++++++---
>   1 file changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/net/tls/tls_main.c b/net/tls/tls_main.c
> index 90b7f253d363..e712b2faeb81 100644
> --- a/net/tls/tls_main.c
> +++ b/net/tls/tls_main.c
> @@ -616,6 +616,7 @@ static int do_tls_setsockopt_conf(struct sock *sk, sockptr_t optval,
>   	struct tls_crypto_info *alt_crypto_info;
>   	struct tls_context *ctx = tls_get_ctx(sk);
>   	const struct tls_cipher_desc *cipher_desc;
> +	union tls_crypto_context *crypto_ctx;
>   	int rc = 0;
>   	int conf;
>   
> @@ -623,13 +624,15 @@ static int do_tls_setsockopt_conf(struct sock *sk, sockptr_t optval,
>   		return -EINVAL;
>   
>   	if (tx) {
> -		crypto_info = &ctx->crypto_send.info;
> +		crypto_ctx = &ctx->crypto_send;
>   		alt_crypto_info = &ctx->crypto_recv.info;
>   	} else {
> -		crypto_info = &ctx->crypto_recv.info;
> +		crypto_ctx = &ctx->crypto_recv;
>   		alt_crypto_info = &ctx->crypto_send.info;
>   	}
>   
> +	crypto_info = &crypto_ctx->info;
> +
>   	/* Currently we don't support set crypto info more than one time */
>   	if (TLS_CRYPTO_INFO_READY(crypto_info))
>   		return -EBUSY;
> @@ -710,7 +713,7 @@ static int do_tls_setsockopt_conf(struct sock *sk, sockptr_t optval,
>   	return 0;
>   
>   err_crypto_info:
> -	memzero_explicit(crypto_info, sizeof(union tls_crypto_context));
> +	memzero_explicit(crypto_ctx, sizeof(union tls_crypto_context));

nit: That's a good fix to aid static analyzers, and reviewers.
Now it's also easy to follow the standard style and pass
sizeof(*crypto_ctx) instead of the type.

>   	return rc;
>   }

Re: [PATCH net-next] net: tls: Pass union tls_crypto_context pointer to memzero_explicit

[Simon Horman]

On Fri, Jul 05, 2024 at 03:54:59PM +0200, Przemek Kitszel wrote:
> On 7/5/24 15:41, Simon Horman wrote:
> > Pass union tls_crypto_context pointer, rather than struct
> > tls_crypto_info pointer, to memzero_explicit().
> > 
> > The address of the pointer is the same before and after.
> > But the new construct means that the size of the dereferenced pointer type
> > matches the size being zeroed. Which aids static analysis.
> > 
> > As reported by Smatch:
> > 
> >    .../tls_main.c:842 do_tls_setsockopt_conf() error: memzero_explicit() 'crypto_info' too small (4 vs 56)
> > 
> > No functional change intended.
> > Compile tested only.
> > 
> > Signed-off-by: Simon Horman <horms@kernel.org>
> 
> Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
> one small nitpick only

...

> > @@ -710,7 +713,7 @@ static int do_tls_setsockopt_conf(struct sock *sk, sockptr_t optval,
> >   	return 0;
> >   err_crypto_info:
> > -	memzero_explicit(crypto_info, sizeof(union tls_crypto_context));
> > +	memzero_explicit(crypto_ctx, sizeof(union tls_crypto_context));
> 
> nit: That's a good fix to aid static analyzers, and reviewers.
> Now it's also easy to follow the standard style and pass
> sizeof(*crypto_ctx) instead of the type.

Thanks, that is a good suggestion.
I'll incorporate it in a v2.