load_powerpc.c

  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 <asm/secure_boot.h>
 14#include <asm/secvar.h>
 15#include "keyring_handler.h"
 16#include "../integrity.h"
 17
 18#define extract_esl(db, data, size, offset)	\
 19	do { db = data + offset; size = size - offset; } while (0)
 20
 21/*
 22 * Get a certificate list blob from the named secure variable.
 23 *
 24 * Returns:
 25 *  - a pointer to a kmalloc'd buffer containing the cert list on success
 26 *  - NULL if the key does not exist
 27 *  - an ERR_PTR on error
 28 */
 29static __init void *get_cert_list(u8 *key, unsigned long keylen, u64 *size)
 30{
 31	int rc;
 32	void *db;
 33
 34	rc = secvar_ops->get(key, keylen, NULL, size);
 35	if (rc) {
 36		if (rc == -ENOENT)
 37			return NULL;
 38		return ERR_PTR(rc);
 39	}
 40
 41	db = kmalloc(*size, GFP_KERNEL);
 42	if (!db)
 43		return ERR_PTR(-ENOMEM);
 44
 45	rc = secvar_ops->get(key, keylen, db, size);
 46	if (rc) {
 47		kfree(db);
 48		return ERR_PTR(rc);
 49	}
 50
 51	return db;
 52}
 53
 54/*
 55 * Load the certs contained in the keys databases into the platform trusted
 56 * keyring and the blacklisted X.509 cert SHA256 hashes into the blacklist
 57 * keyring.
 58 */
 59static int __init load_powerpc_certs(void)
 60{
 61	void *db = NULL, *dbx = NULL, *data = NULL;
 62	void *trustedca;
 63	void *moduledb;
 64	u64 dsize = 0;
 65	u64 offset = 0;
 66	int rc = 0;
 67	ssize_t len;
 68	char buf[32];
 69
 70	if (!secvar_ops)
 71		return -ENODEV;
 72
 73	len = secvar_ops->format(buf, sizeof(buf));
 74	if (len <= 0)
 75		return -ENODEV;
 76
 77	// Check for known secure boot implementations from OPAL or PLPKS
 78	if (strcmp("ibm,edk2-compat-v1", buf) && strcmp("ibm,plpks-sb-v1", buf) &&
 79	    strcmp("ibm,plpks-sb-v0", buf)) {
 80		pr_err("Unsupported secvar implementation \"%s\", not loading certs\n", buf);
 81		return -ENODEV;
 82	}
 83
 84	if (strcmp("ibm,plpks-sb-v1", buf) == 0 || strcmp("ibm,plpks-sb-v0", buf) == 0)
 85		/* PLPKS authenticated variables ESL data is prefixed with 8 bytes of timestamp */
 86		offset = 8;
 87
 88	/*
 89	 * Get db, and dbx. They might not exist, so it isn't an error if we
 90	 * can't get them.
 91	 */
 92	data = get_cert_list("db", 3, &dsize);
 93	if (!data) {
 94		pr_info("Couldn't get db list from firmware\n");
 95	} else if (IS_ERR(data)) {
 96		rc = PTR_ERR(data);
 97		pr_err("Error reading db from firmware: %d\n", rc);
 98		return rc;
 99	} else {
100		extract_esl(db, data, dsize, offset);
101
102		rc = parse_efi_signature_list("powerpc:db", db, dsize,
103					      get_handler_for_db);
104		if (rc)
105			pr_err("Couldn't parse db signatures: %d\n", rc);
106		kfree(data);
107	}
108
109	data = get_cert_list("dbx", 4,  &dsize);
110	if (!data) {
111		pr_info("Couldn't get dbx list from firmware\n");
112	} else if (IS_ERR(data)) {
113		rc = PTR_ERR(data);
114		pr_err("Error reading dbx from firmware: %d\n", rc);
115		return rc;
116	} else {
117		extract_esl(dbx, data, dsize, offset);
118
119		rc = parse_efi_signature_list("powerpc:dbx", dbx, dsize,
120					      get_handler_for_dbx);
121		if (rc)
122			pr_err("Couldn't parse dbx signatures: %d\n", rc);
123		kfree(data);
124	}
125
126	data = get_cert_list("trustedcadb", 12,  &dsize);
127	if (!data) {
128		pr_info("Couldn't get trustedcadb list from firmware\n");
129	} else if (IS_ERR(data)) {
130		rc = PTR_ERR(data);
131		pr_err("Error reading trustedcadb from firmware: %d\n", rc);
132	} else {
133		extract_esl(trustedca, data, dsize, offset);
134
135		rc = parse_efi_signature_list("powerpc:trustedca", trustedca, dsize,
136					      get_handler_for_ca_keys);
137		if (rc)
138			pr_err("Couldn't parse trustedcadb signatures: %d\n", rc);
139		kfree(data);
140	}
141
142	data = get_cert_list("moduledb", 9,  &dsize);
143	if (!data) {
144		pr_info("Couldn't get moduledb list from firmware\n");
145	} else if (IS_ERR(data)) {
146		rc = PTR_ERR(data);
147		pr_err("Error reading moduledb from firmware: %d\n", rc);
148	} else {
149		extract_esl(moduledb, data, dsize, offset);
150
151		rc = parse_efi_signature_list("powerpc:moduledb", moduledb, dsize,
152					      get_handler_for_code_signing_keys);
153		if (rc)
154			pr_err("Couldn't parse moduledb signatures: %d\n", rc);
155		kfree(data);
156	}
157
158	return rc;
159}
160late_initcall(load_powerpc_certs);