// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (c) 2023 Hannes Reinecke, SUSE Labs
 */

#include <linux/module.h>
#include <linux/seq_file.h>
#include <linux/key-type.h>
#include <keys/user-type.h>
#include <linux/nvme.h>
#include <linux/nvme-tcp.h>
#include <linux/nvme-keyring.h>

static struct key *nvme_keyring;

key_serial_t nvme_keyring_id(void)
{
        return nvme_keyring->serial;
}
EXPORT_SYMBOL_GPL(nvme_keyring_id);

static bool nvme_tls_psk_revoked(struct key *psk)
{
        return test_bit(KEY_FLAG_REVOKED, &psk->flags) ||
                test_bit(KEY_FLAG_INVALIDATED, &psk->flags);
}

struct key *nvme_tls_key_lookup(key_serial_t key_id)
{
        struct key *key = key_lookup(key_id);

        if (IS_ERR(key)) {
                pr_err("key id %08x not found\n", key_id);
                return key;
        }
        if (nvme_tls_psk_revoked(key)) {
                pr_err("key id %08x revoked\n", key_id);
                return ERR_PTR(-EKEYREVOKED);
        }
        return key;
}
EXPORT_SYMBOL_GPL(nvme_tls_key_lookup);

static void nvme_tls_psk_describe(const struct key *key, struct seq_file *m)
{
        seq_puts(m, key->description);
        seq_printf(m, ": %u", key->datalen);
}

static bool nvme_tls_psk_match(const struct key *key,
                               const struct key_match_data *match_data)
{
        const char *match_id;
        size_t match_len;

        if (!key->description) {
                pr_debug("%s: no key description\n", __func__);
                return false;
        }
        if (!match_data->raw_data) {
                pr_debug("%s: no match data\n", __func__);
                return false;
        }
        match_id = match_data->raw_data;
        match_len = strlen(match_id);
        pr_debug("%s: match '%s' '%s' len %zd\n",
                 __func__, match_id, key->description, match_len);
        return !memcmp(key->description, match_id, match_len);
}

static int nvme_tls_psk_match_preparse(struct key_match_data *match_data)
{
        match_data->lookup_type = KEYRING_SEARCH_LOOKUP_ITERATE;
        match_data->cmp = nvme_tls_psk_match;
        return 0;
}

static struct key_type nvme_tls_psk_key_type = {
        .name           = "psk",
        .flags          = KEY_TYPE_NET_DOMAIN,
        .preparse       = user_preparse,
        .free_preparse  = user_free_preparse,
        .match_preparse = nvme_tls_psk_match_preparse,
        .instantiate    = generic_key_instantiate,
        .revoke         = user_revoke,
        .destroy        = user_destroy,
        .describe       = nvme_tls_psk_describe,
        .read           = user_read,
};

static struct key *nvme_tls_psk_lookup(struct key *keyring,
                const char *hostnqn, const char *subnqn,
                u8 hmac, u8 psk_ver, bool generated)
{
        char *identity;
        size_t identity_len = (NVMF_NQN_SIZE) * 2 + 11;
        key_ref_t keyref;
        key_serial_t keyring_id;

        identity = kzalloc(identity_len, GFP_KERNEL);
        if (!identity)
                return ERR_PTR(-ENOMEM);

        snprintf(identity, identity_len, "NVMe%u%c%02u %s %s",
                 psk_ver, generated ? 'G' : 'R', hmac, hostnqn, subnqn);

        if (!keyring)
                keyring = nvme_keyring;
        keyring_id = key_serial(keyring);
        pr_debug("keyring %x lookup tls psk '%s'\n",
                 keyring_id, identity);
        keyref = keyring_search(make_key_ref(keyring, true),
                                &nvme_tls_psk_key_type,
                                identity, false);
        if (IS_ERR(keyref)) {
                pr_debug("lookup tls psk '%s' failed, error %ld\n",
                         identity, PTR_ERR(keyref));
                kfree(identity);
                return ERR_PTR(-ENOKEY);
        }
        kfree(identity);

        return key_ref_to_ptr(keyref);
}

/**
 * nvme_tls_psk_refresh - Refresh TLS PSK
 * @keyring: Keyring holding the TLS PSK
 * @hostnqn: Host NQN to use
 * @subnqn: Subsystem NQN to use
 * @hmac_id: Hash function identifier
 * @data: TLS PSK key material
 * @data_len: Length of @data
 * @digest: TLS PSK digest
 *
 * Refresh a generated version 1 TLS PSK with the identity generated
 * from @hmac_id, @hostnqn, @subnqn, and @digest in the keyring given
 * by @keyring.
 *
 * Returns the updated key success or an error pointer otherwise.
 */
struct key *nvme_tls_psk_refresh(struct key *keyring,
                const char *hostnqn, const char *subnqn, u8 hmac_id,
                u8 *data, size_t data_len, const char *digest)
{
        key_perm_t keyperm =
                KEY_POS_SEARCH | KEY_POS_VIEW | KEY_POS_READ |
                KEY_POS_WRITE | KEY_POS_LINK | KEY_POS_SETATTR |
                KEY_USR_SEARCH | KEY_USR_VIEW | KEY_USR_READ;
        char *identity;
        key_ref_t keyref;
        key_serial_t keyring_id;
        struct key *key;

        if (!hostnqn || !subnqn || !data || !data_len)
                return ERR_PTR(-EINVAL);

        identity = kasprintf(GFP_KERNEL, "NVMe1G%02d %s %s %s",
                 hmac_id, hostnqn, subnqn, digest);
        if (!identity)
                return ERR_PTR(-ENOMEM);

        if (!keyring)
                keyring = nvme_keyring;
        keyring_id = key_serial(keyring);
        pr_debug("keyring %x refresh tls psk '%s'\n",
                 keyring_id, identity);
        keyref = key_create_or_update(make_key_ref(keyring, true),
                                "psk", identity, data, data_len,
                                keyperm, KEY_ALLOC_NOT_IN_QUOTA |
                                      KEY_ALLOC_BUILT_IN |
                                      KEY_ALLOC_BYPASS_RESTRICTION);
        if (IS_ERR(keyref)) {
                pr_debug("refresh tls psk '%s' failed, error %ld\n",
                         identity, PTR_ERR(keyref));
                kfree(identity);
                return ERR_PTR(-ENOKEY);
        }
        kfree(identity);
        /*
         * Set the default timeout to 1 hour
         * as suggested in TP8018.
         */
        key = key_ref_to_ptr(keyref);
        key_set_timeout(key, 3600);
        return key;
}
EXPORT_SYMBOL_GPL(nvme_tls_psk_refresh);

/*
 * NVMe PSK priority list
 *
 * 'Retained' PSKs (ie 'generated == false') should be preferred to 'generated'
 * PSKs, PSKs with hash (psk_ver 1) should be preferred to PSKs without hash
 * (psk_ver 0), and SHA-384 should be preferred to SHA-256.
 */
static struct nvme_tls_psk_priority_list {
        bool generated;
        u8 psk_ver;
        enum nvme_tcp_tls_cipher cipher;
} nvme_tls_psk_prio[] = {
        { .generated = false,
          .psk_ver = 1,
          .cipher = NVME_TCP_TLS_CIPHER_SHA384, },
        { .generated = false,
          .psk_ver = 1,
          .cipher = NVME_TCP_TLS_CIPHER_SHA256, },
        { .generated = false,
          .psk_ver = 0,
          .cipher = NVME_TCP_TLS_CIPHER_SHA384, },
        { .generated = false,
          .psk_ver = 0,
          .cipher = NVME_TCP_TLS_CIPHER_SHA256, },
        { .generated = true,
          .psk_ver = 1,
          .cipher = NVME_TCP_TLS_CIPHER_SHA384, },
        { .generated = true,
          .psk_ver = 1,
          .cipher = NVME_TCP_TLS_CIPHER_SHA256, },
        { .generated = true,
          .psk_ver = 0,
          .cipher = NVME_TCP_TLS_CIPHER_SHA384, },
        { .generated = true,
          .psk_ver = 0,
          .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;
                u8 ver = nvme_tls_psk_prio[prio].psk_ver;
                enum nvme_tcp_tls_cipher cipher = nvme_tls_psk_prio[prio].cipher;

                tls_key = nvme_tls_psk_lookup(keyring, hostnqn, subnqn,
                                              cipher, ver, 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);

static int __init nvme_keyring_init(void)
{
        int err;

        nvme_keyring = keyring_alloc(".nvme",
                                     GLOBAL_ROOT_UID, GLOBAL_ROOT_GID,
                                     current_cred(),
                                     (KEY_POS_ALL & ~KEY_POS_SETATTR) |
                                     (KEY_USR_ALL & ~KEY_USR_SETATTR),
                                     KEY_ALLOC_NOT_IN_QUOTA, NULL, NULL);
        if (IS_ERR(nvme_keyring))
                return PTR_ERR(nvme_keyring);

        err = register_key_type(&nvme_tls_psk_key_type);
        if (err) {
                key_put(nvme_keyring);
                return err;
        }
        return 0;
}

static void __exit nvme_keyring_exit(void)
{
        unregister_key_type(&nvme_tls_psk_key_type);
        key_revoke(nvme_keyring);
        key_put(nvme_keyring);
}

MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Hannes Reinecke <hare@suse.de>");
MODULE_DESCRIPTION("NVMe Keyring implementation");
module_init(nvme_keyring_init);
module_exit(nvme_keyring_exit);