[PATCH 05/17] nvme-keyring: implement nvme_tls_psk_default()

[Max Gurtovoy]

Hannes,
I wonder if we can squash the keyring patches 1/17 + 2/17 + 5/17 to a 
single patch ?
And start the series with some preparations in the nvme/tcp for it to 
compile..
This will reduce the amount of commits and simplify the review.

On 19/04/2023 9:57, Hannes Reinecke wrote:
> Implement a function to select the preferred PSK for TLS.
> 
> Signed-off-by: Hannes Reinecke <hare at suse.de>
> ---
>   drivers/nvme/common/keyring.c | 48 +++++++++++++++++++++++++++++++++++
>   include/linux/nvme-keyring.h  |  8 ++++++
>   2 files changed, 56 insertions(+)
> 
> diff --git a/drivers/nvme/common/keyring.c b/drivers/nvme/common/keyring.c
> index 494dd365052e..f8d9a208397b 100644
> --- a/drivers/nvme/common/keyring.c
> +++ b/drivers/nvme/common/keyring.c
> @@ -5,6 +5,7 @@
>   
>   #include <linux/module.h>
>   #include <linux/seq_file.h>
> +#include <linux/key.h>
>   #include <linux/key-type.h>
>   #include <keys/user-type.h>
>   #include <linux/nvme.h>
> @@ -103,6 +104,53 @@ static struct key *nvme_tls_psk_lookup(struct key *keyring,
>   	return key_ref_to_ptr(keyref);
>   }
>   
> +/*
> + * NVMe PSK priority list
> + *
> + * 'Retained' PSKs (ie 'generated == false')
> + * should be preferred to 'generated' PSKs,
> + * and SHA-384 should be preferred to SHA-256.
> + */
> +struct nvme_tls_psk_priority_list {
> +	bool generated;
> +	enum nvme_tcp_tls_cipher cipher;
> +} nvme_tls_psk_prio[] = {
> +	{ .generated = false,
> +	  .cipher = NVME_TCP_TLS_CIPHER_SHA384, },
> +	{ .generated = false,
> +	  .cipher = NVME_TCP_TLS_CIPHER_SHA256, },
> +	{ .generated = true,
> +	  .cipher = NVME_TCP_TLS_CIPHER_SHA384, },
> +	{ .generated = true,
> +	  .cipher = NVME_TCP_TLS_CIPHER_SHA256, },
> +};
> +
> +/*
> + * nvme_tls_psk_default - Return the preferred PSK to use for TLS ClientHello
> + */
> +key_serial_t nvme_tls_psk_default(struct key *keyring,
> +		      const char *hostnqn, const char *subnqn)
> +{
> +	struct key *tls_key;
> +	key_serial_t tls_key_id;
> +	int prio;
> +
> +	for (prio = 0; prio < ARRAY_SIZE(nvme_tls_psk_prio); prio++) {
> +		bool generated = nvme_tls_psk_prio[prio].generated;
> +		enum nvme_tcp_tls_cipher cipher = nvme_tls_psk_prio[prio].cipher;
> +
> +		tls_key = nvme_tls_psk_lookup(keyring, hostnqn, subnqn,
> +					      cipher, generated);
> +		if (!IS_ERR(tls_key)) {
> +			tls_key_id = tls_key->serial;
> +			key_put(tls_key);
> +			return tls_key_id;
> +		}
> +	}
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(nvme_tls_psk_default);
> +
>   int nvme_keyring_init(void)
>   {
>   	int err;
> diff --git a/include/linux/nvme-keyring.h b/include/linux/nvme-keyring.h
> index 32bd264a71e6..4efea9dd967c 100644
> --- a/include/linux/nvme-keyring.h
> +++ b/include/linux/nvme-keyring.h
> @@ -8,12 +8,20 @@
>   
>   #ifdef CONFIG_NVME_KEYRING
>   
> +key_serial_t nvme_tls_psk_default(struct key *keyring,
> +		const char *hostnqn, const char *subnqn);
> +
>   key_serial_t nvme_keyring_id(void);
>   int nvme_keyring_init(void);
>   void nvme_keyring_exit(void);
>   
>   #else
>   
> +static inline key_serial_t nvme_tls_psk_default(struct key *keyring,
> +		const char *hostnqn, const char *subnqn)
> +{
> +	return 0;
> +}
>   static inline key_serial_t nvme_keyring_id(void)
>   {
>   	return 0;