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

Hannes Reinecke
2023-08-10T15:06:50Z

Implement a function to select the preferred PSK for TLS.
A 'retained' PSK should be preferred over a 'generated' PSK,
and SHA-384 should be preferred to SHA-256.

Signed-off-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
---
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;
--
2.35.3