// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2019 IBM Corporation
 * Author: Nayna Jain
 *
 *      - loads keys and hashes stored and controlled by the firmware.
 */
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/cred.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <asm/secure_boot.h>
#include <asm/secvar.h>
#include "keyring_handler.h"
#include "../integrity.h"

#define extract_esl(db, data, size, offset)     \
        do { db = data + offset; size = size - offset; } while (0)

/*
 * Get a certificate list blob from the named secure variable.
 *
 * Returns:
 *  - a pointer to a kmalloc'd buffer containing the cert list on success
 *  - NULL if the key does not exist
 *  - an ERR_PTR on error
 */
static __init void *get_cert_list(u8 *key, unsigned long keylen, u64 *size)
{
        int rc;
        void *db;

        rc = secvar_ops->get(key, keylen, NULL, size);
        if (rc) {
                if (rc == -ENOENT)
                        return NULL;
                return ERR_PTR(rc);
        }

        db = kmalloc(*size, GFP_KERNEL);
        if (!db)
                return ERR_PTR(-ENOMEM);

        rc = secvar_ops->get(key, keylen, db, size);
        if (rc) {
                kfree(db);
                return ERR_PTR(rc);
        }

        return db;
}

/*
 * Load the certs contained in the keys databases into the platform trusted
 * keyring and the blacklisted X.509 cert SHA256 hashes into the blacklist
 * keyring.
 */
static int __init load_powerpc_certs(void)
{
        void *db = NULL, *dbx = NULL, *data = NULL;
        void *trustedca;
        void *moduledb;
        u64 dsize = 0;
        u64 offset = 0;
        int rc = 0;
        ssize_t len;
        char buf[32];

        if (!secvar_ops)
                return -ENODEV;

        len = secvar_ops->format(buf, sizeof(buf));
        if (len <= 0)
                return -ENODEV;

        // Check for known secure boot implementations from OPAL or PLPKS
        if (strcmp("ibm,edk2-compat-v1", buf) && strcmp("ibm,plpks-sb-v1", buf) &&
            strcmp("ibm,plpks-sb-v0", buf)) {
                pr_err("Unsupported secvar implementation \"%s\", not loading certs\n", buf);
                return -ENODEV;
        }

        if (strcmp("ibm,plpks-sb-v1", buf) == 0 || strcmp("ibm,plpks-sb-v0", buf) == 0)
                /* PLPKS authenticated variables ESL data is prefixed with 8 bytes of timestamp */
                offset = 8;

        /*
         * Get db, and dbx. They might not exist, so it isn't an error if we
         * can't get them.
         */
        data = get_cert_list("db", 3, &dsize);
        if (!data) {
                pr_info("Couldn't get db list from firmware\n");
        } else if (IS_ERR(data)) {
                rc = PTR_ERR(data);
                pr_err("Error reading db from firmware: %d\n", rc);
                return rc;
        } else {
                extract_esl(db, data, dsize, offset);

                rc = parse_efi_signature_list("powerpc:db", db, dsize,
                                              get_handler_for_db);
                if (rc)
                        pr_err("Couldn't parse db signatures: %d\n", rc);
                kfree(data);
        }

        data = get_cert_list("dbx", 4,  &dsize);
        if (!data) {
                pr_info("Couldn't get dbx list from firmware\n");
        } else if (IS_ERR(data)) {
                rc = PTR_ERR(data);
                pr_err("Error reading dbx from firmware: %d\n", rc);
                return rc;
        } else {
                extract_esl(dbx, data, dsize, offset);

                rc = parse_efi_signature_list("powerpc:dbx", dbx, dsize,
                                              get_handler_for_dbx);
                if (rc)
                        pr_err("Couldn't parse dbx signatures: %d\n", rc);
                kfree(data);
        }

        data = get_cert_list("trustedcadb", 12,  &dsize);
        if (!data) {
                pr_info("Couldn't get trustedcadb list from firmware\n");
        } else if (IS_ERR(data)) {
                rc = PTR_ERR(data);
                pr_err("Error reading trustedcadb from firmware: %d\n", rc);
        } else {
                extract_esl(trustedca, data, dsize, offset);

                rc = parse_efi_signature_list("powerpc:trustedca", trustedca, dsize,
                                              get_handler_for_ca_keys);
                if (rc)
                        pr_err("Couldn't parse trustedcadb signatures: %d\n", rc);
                kfree(data);
        }

        data = get_cert_list("moduledb", 9,  &dsize);
        if (!data) {
                pr_info("Couldn't get moduledb list from firmware\n");
        } else if (IS_ERR(data)) {
                rc = PTR_ERR(data);
                pr_err("Error reading moduledb from firmware: %d\n", rc);
        } else {
                extract_esl(moduledb, data, dsize, offset);

                rc = parse_efi_signature_list("powerpc:moduledb", moduledb, dsize,
                                              get_handler_for_code_signing_keys);
                if (rc)
                        pr_err("Couldn't parse moduledb signatures: %d\n", rc);
                kfree(data);
        }

        return rc;
}
late_initcall(load_powerpc_certs);