Re: [PATCH v3 4/4] powerpc: load firmware trusted keys/hashes into kernel keyring

Mimi Zohar
2019-09-03T22:55:06Z

On Mon, 2019-08-26 at 09:23 -0400, Nayna Jain wrote:
> The keys used to verify the Host OS kernel are managed by firmware as
> secure variables. This patch loads the verification keys into the .platform
> keyring and revocation hashes into .blacklist keyring. This enables
> verification and loading of the kernels signed by the boot time keys which
> are trusted by firmware.
>
> Signed-off-by: Nayna Jain <nayna@linux.ibm.com>

Feel free to add my tag after addressing the formatting issues.

Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>

> diff --git a/security/integrity/platform_certs/load_powerpc.c b/security/integrity/platform_certs/load_powerpc.c
> new file mode 100644
> index 000000000000..359d5063d4da
> --- /dev/null
> +++ b/security/integrity/platform_certs/load_powerpc.c
> @@ -0,0 +1,88 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2019 IBM Corporation
> + * Author: Nayna Jain <nayna@linux.ibm.com>
> + *
> + * - 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/secboot.h>
> +#include <asm/secvar.h>
> +#include "keyring_handler.h"
> +
> +/*
> + * Get a certificate list blob from the named secure variable.
> + */
> +static __init void *get_cert_list(u8 *key, unsigned long keylen, uint64_t *size)
> +{
> + int rc;
> + void *db;
> +
> + rc = secvar_ops->get(key, keylen, NULL, size);
> + if (rc) {
> + pr_err("Couldn't get size: %d\n", rc);
> + return NULL;
> + }
> +
> + db = kmalloc(*size, GFP_KERNEL);
> + if (!db)
> + return NULL;
> +
> + rc = secvar_ops->get(key, keylen, db, size);
> + if (rc) {
> + kfree(db);
> + pr_err("Error reading db var: %d\n", rc);
> + return NULL;
> + }
> +
> + 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;
> + uint64_t dbsize = 0, dbxsize = 0;
> + int rc = 0;
> +
> + if (!secvar_ops)
> + return -ENODEV;
> +
> + /* Get db, and dbx. They might not exist, so it isn't
> + * an error if we can't get them.
> + */
> + db = get_cert_list("db", 3, &dbsize);
> + if (!db) {
> + pr_err("Couldn't get db list from firmware\n");
> + } else {
> + rc = parse_efi_signature_list("powerpc:db",
> + db, dbsize, get_handler_for_db);
> + if (rc)
> + pr_err("Couldn't parse db signatures: %d\n",
> + rc);

There's no need to split this line.

> + kfree(db);
> + }
> +
> + dbx = get_cert_list("dbx", 3, &dbxsize);
> + if (!dbx) {
> + pr_info("Couldn't get dbx list from firmware\n");
> + } else {
> + rc = parse_efi_signature_list("powerpc:dbx",
> + dbx, dbxsize,
> + get_handler_for_dbx);

Formatting of this line is off.

> + if (rc)
> + pr_err("Couldn't parse dbx signatures: %d\n", rc);
> + kfree(dbx);
> + }
> +
> + return rc;
> +}
> +late_initcall(load_powerpc_certs);