LXR linux/security/integrity/platform_certs/load

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * Copyright (C) 2019 IBM Corporation
   4 * Author: Nayna Jain
   5 *
   6 *      - loads keys and hashes stored and controlled by the firmware.
   7 */
   8#include <linux/kernel.h>
   9#include <linux/sched.h>
  10#include <linux/cred.h>
  11#include <linux/err.h>
  12#include <linux/slab.h>
  13#include <linux/of.h>
  14#include <asm/secure_boot.h>
  15#include <asm/secvar.h>
  16#include "keyring_handler.h"
  17
  18/*
  19 * Get a certificate list blob from the named secure variable.
  20 */
  21static __init void *get_cert_list(u8 *key, unsigned long keylen, uint64_t *size)
  22{
  23        int rc;
  24        void *db;
  25
  26        rc = secvar_ops->get(key, keylen, NULL, size);
  27        if (rc) {
  28                pr_err("Couldn't get size: %d\n", rc);
  29                return NULL;
  30        }
  31
  32        db = kmalloc(*size, GFP_KERNEL);
  33        if (!db)
  34                return NULL;
  35
  36        rc = secvar_ops->get(key, keylen, db, size);
  37        if (rc) {
  38                kfree(db);
  39                pr_err("Error reading %s var: %d\n", key, rc);
  40                return NULL;
  41        }
  42
  43        return db;
  44}
  45
  46/*
  47 * Load the certs contained in the keys databases into the platform trusted
  48 * keyring and the blacklisted X.509 cert SHA256 hashes into the blacklist
  49 * keyring.
  50 */
  51static int __init load_powerpc_certs(void)
  52{
  53        void *db = NULL, *dbx = NULL;
  54        uint64_t dbsize = 0, dbxsize = 0;
  55        int rc = 0;
  56        struct device_node *node;
  57
  58        if (!secvar_ops)
  59                return -ENODEV;
  60
  61        /* The following only applies for the edk2-compat backend. */
  62        node = of_find_compatible_node(NULL, NULL, "ibm,edk2-compat-v1");
  63        if (!node)
  64                return -ENODEV;
  65
  66        /*
  67         * Get db, and dbx. They might not exist, so it isn't an error if we
  68         * can't get them.
  69         */
  70        db = get_cert_list("db", 3, &dbsize);
  71        if (!db) {
  72                pr_err("Couldn't get db list from firmware\n");
  73        } else {
  74                rc = parse_efi_signature_list("powerpc:db", db, dbsize,
  75                                              get_handler_for_db);
  76                if (rc)
  77                        pr_err("Couldn't parse db signatures: %d\n", rc);
  78                kfree(db);
  79        }
  80
  81        dbx = get_cert_list("dbx", 4,  &dbxsize);
  82        if (!dbx) {
  83                pr_info("Couldn't get dbx list from firmware\n");
  84        } else {
  85                rc = parse_efi_signature_list("powerpc:dbx", dbx, dbxsize,
  86                                              get_handler_for_dbx);
  87                if (rc)
  88                        pr_err("Couldn't parse dbx signatures: %d\n", rc);
  89                kfree(dbx);
  90        }
  91
  92        of_node_put(node);
  93
  94        return rc;
  95}
  96late_initcall(load_powerpc_certs);
  97