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		pr_err("Unsupported secvar implementation \"%s\", not loading certs\n", buf);
80		return -ENODEV;
81	}
82
83	if (strcmp("ibm,plpks-sb-v1", buf) == 0)
84		/* PLPKS authenticated variables ESL data is prefixed with 8 bytes of timestamp */
85		offset = 8;
86
87	/*
88	 * Get db, and dbx. They might not exist, so it isn't an error if we
89	 * can't get them.
90	 */
91	data = get_cert_list("db", 3, &dsize);
92	if (!data) {
93		pr_info("Couldn't get db list from firmware\n");
94	} else if (IS_ERR(data)) {
95		rc = PTR_ERR(data);
96		pr_err("Error reading db from firmware: %d\n", rc);
97		return rc;
98	} else {
99		extract_esl(db, data, dsize, offset);
100
101		rc = parse_efi_signature_list("powerpc:db", db, dsize,
102					      get_handler_for_db);
103		if (rc)
104			pr_err("Couldn't parse db signatures: %d\n", rc);
105		kfree(data);
106	}
107
108	data = get_cert_list("dbx", 4,  &dsize);
109	if (!data) {
110		pr_info("Couldn't get dbx list from firmware\n");
111	} else if (IS_ERR(data)) {
112		rc = PTR_ERR(data);
113		pr_err("Error reading dbx from firmware: %d\n", rc);
114		return rc;
115	} else {
116		extract_esl(dbx, data, dsize, offset);
117
118		rc = parse_efi_signature_list("powerpc:dbx", dbx, dsize,
119					      get_handler_for_dbx);
120		if (rc)
121			pr_err("Couldn't parse dbx signatures: %d\n", rc);
122		kfree(data);
123	}
124
125	data = get_cert_list("trustedcadb", 12,  &dsize);
126	if (!data) {
127		pr_info("Couldn't get trustedcadb list from firmware\n");
128	} else if (IS_ERR(data)) {
129		rc = PTR_ERR(data);
130		pr_err("Error reading trustedcadb from firmware: %d\n", rc);
131	} else {
132		extract_esl(trustedca, data, dsize, offset);
133
134		rc = parse_efi_signature_list("powerpc:trustedca", trustedca, dsize,
135					      get_handler_for_ca_keys);
136		if (rc)
137			pr_err("Couldn't parse trustedcadb signatures: %d\n", rc);
138		kfree(data);
139	}
140
141	data = get_cert_list("moduledb", 9,  &dsize);
142	if (!data) {
143		pr_info("Couldn't get moduledb list from firmware\n");
144	} else if (IS_ERR(data)) {
145		rc = PTR_ERR(data);
146		pr_err("Error reading moduledb from firmware: %d\n", rc);
147	} else {
148		extract_esl(moduledb, data, dsize, offset);
149
150		rc = parse_efi_signature_list("powerpc:moduledb", moduledb, dsize,
151					      get_handler_for_code_signing_keys);
152		if (rc)
153			pr_err("Couldn't parse moduledb signatures: %d\n", rc);
154		kfree(data);
155	}
156
157	return rc;
158}
159late_initcall(load_powerpc_certs);
160