netdev - Re: [RFC PATCH net-next 2/2] net: tls: export protocol version and cipher to socket diag

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Date:   Wed, 5 Jun 2019 16:25:55 -0700
From:   Jakub Kicinski <jakub.kicinski@...ronome.com>
To:     Davide Caratti <dcaratti@...hat.com>
Cc:     "David S. Miller" <davem@...emloft.net>,
        Dave Watson <davejwatson@...com>,
        Boris Pismenny <borisp@...lanox.com>,
        Aviad Yehezkel <aviadye@...lanox.com>,
        John Fastabend <john.fastabend@...il.com>,
        Daniel Borkmann <daniel@...earbox.net>, netdev@...r.kernel.org
Subject: Re: [RFC PATCH net-next 2/2] net: tls: export protocol version and
 cipher to socket diag

On Wed,  5 Jun 2019 17:39:23 +0200, Davide Caratti wrote:
> When an application configures kernel TLS on top of a TCP socket, it's
> now possible for inet_diag_handler to collect information regarding the
> protocol version and the cipher, in case INET_DIAG_INFO is requested.
> 
> Signed-off-by: Davide Caratti <dcaratti@...hat.com>
> ---
>  include/uapi/linux/inet_diag.h |  1 +
>  include/uapi/linux/tls.h       |  8 +++++++
>  net/tls/tls_main.c             | 43 ++++++++++++++++++++++++++++++++++
>  3 files changed, 52 insertions(+)
> 
> diff --git a/include/uapi/linux/inet_diag.h b/include/uapi/linux/inet_diag.h
> index 844133de3212..92208535c096 100644
> --- a/include/uapi/linux/inet_diag.h
> +++ b/include/uapi/linux/inet_diag.h
> @@ -161,6 +161,7 @@ enum {
>  
>  enum {
>  	ULP_INFO_NAME,
> +	ULP_INFO_TLS,
>  	__ULP_INFO_MAX,
>  };
>  
> diff --git a/include/uapi/linux/tls.h b/include/uapi/linux/tls.h
> index 5b9c26753e46..442348bd2e54 100644
> --- a/include/uapi/linux/tls.h
> +++ b/include/uapi/linux/tls.h
> @@ -109,4 +109,12 @@ struct tls12_crypto_info_aes_ccm_128 {
>  	unsigned char rec_seq[TLS_CIPHER_AES_CCM_128_REC_SEQ_SIZE];
>  };
>  
> +enum {

USPEC

> +	TLS_INFO_VERSION,
> +	TLS_INFO_CIPHER,

We need some indication of the directions in which kTLS is active
(none, rx, tx, rx/tx).

Also perhaps could you add TLS_SW vs TLS_HW etc. ? :)

> +	__TLS_INFO_MAX,
> +};
> +

Traditionally we put no new line between enum and the max define.

> +#define TLS_INFO_MAX (__TLS_INFO_MAX - 1)
> +
>  #endif /* _UAPI_LINUX_TLS_H */
> diff --git a/net/tls/tls_main.c b/net/tls/tls_main.c
> index fc81ae18cc44..14597526981c 100644
> --- a/net/tls/tls_main.c
> +++ b/net/tls/tls_main.c
> @@ -39,6 +39,7 @@
>  #include <linux/netdevice.h>
>  #include <linux/sched/signal.h>
>  #include <linux/inetdevice.h>
> +#include <linux/inet_diag.h>
> 
>  #include <net/tls.h>
>  
> @@ -798,6 +799,46 @@ static int tls_init(struct sock *sk)
>  	return rc;
>  }
>  
> +static int tls_get_info(struct sock *sk, struct sk_buff *skb)
> +{
> +	struct tls_context *ctx = tls_get_ctx(sk);
> +	struct nlattr *start = 0;

Hm.. NULL?  Does this not give you a warning?

> +	int err = 0;

There should be no need to init this.

> +	if (sk->sk_state != TCP_ESTABLISHED)

Hmm.. why this check?  We never clean up the state once installed until
the socket dies completely (currently, pending John's unhash work).

> +		goto end;

Please don't do this, just return 0; here.

> +	start = nla_nest_start_noflag(skb, ULP_INFO_TLS);
> +	if (!start) {
> +		err = -EMSGSIZE;
> +		goto nla_failure;

		return -EMSGSIZE;

> +	}
> +	err = nla_put_u16(skb, TLS_INFO_VERSION, ctx->prot_info.version);
> +	if (err < 0)
> +		goto nla_failure;
> +	err = nla_put_u16(skb, TLS_INFO_CIPHER, ctx->prot_info.cipher_type);
> +	if (err < 0)
> +		goto nla_failure;
> +	nla_nest_end(skb, start);
> +end:
> +	return err;

	return 0;

> +nla_failure:
> +	nla_nest_cancel(skb, start);
> +	goto end;

	return err;

> +}
> +
> +static size_t tls_get_info_size(struct sock *sk)
> +{
> +	size_t size = 0;
> +
> +	if (sk->sk_state != TCP_ESTABLISHED)
> +		return size;
> +
> +	size +=   nla_total_size(0) /* ULP_INFO_TLS */
> +		+ nla_total_size(sizeof(__u16))	/* TLS_INFO_VERSION */
> +		+ nla_total_size(sizeof(__u16)); /* TLS_INFO_CIPHER */
> +	return size;
> +}

Same comments as on patch 1 and above.

>  void tls_register_device(struct tls_device *device)
>  {
>  	spin_lock_bh(&device_spinlock);

Thanks for working on this, it was on my todo list! :)