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160 lines · 4.0 KiB

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);