1// SPDX-License-Identifier: GPL-2.0-or-later
2/* PKCS#8 Private Key parser [RFC 5208].
3 *
4 * Copyright (C) 2016 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
6 */
7
8#define pr_fmt(fmt) "PKCS8: "fmt
9#include <linux/module.h>
10#include <linux/kernel.h>
11#include <linux/export.h>
12#include <linux/slab.h>
13#include <linux/err.h>
14#include <linux/oid_registry.h>
15#include <keys/asymmetric-subtype.h>
16#include <keys/asymmetric-parser.h>
17#include <crypto/public_key.h>
18#include "pkcs8.asn1.h"
19
20struct pkcs8_parse_context {
21	struct public_key *pub;
22	unsigned long	data;			/* Start of data */
23	enum OID	last_oid;		/* Last OID encountered */
24	enum OID	algo_oid;		/* Algorithm OID */
25	u32		key_size;
26	const void	*key;
27};
28
29/*
30 * Note an OID when we find one for later processing when we know how to
31 * interpret it.
32 */
33int pkcs8_note_OID(void *context, size_t hdrlen,
34		   unsigned char tag,
35		   const void *value, size_t vlen)
36{
37	struct pkcs8_parse_context *ctx = context;
38
39	ctx->last_oid = look_up_OID(value, vlen);
40	if (ctx->last_oid == OID__NR) {
41		char buffer[50];
42
43		sprint_oid(value, vlen, buffer, sizeof(buffer));
44		pr_info("Unknown OID: [%lu] %s\n",
45			(unsigned long)value - ctx->data, buffer);
46	}
47	return 0;
48}
49
50/*
51 * Note the version number of the ASN.1 blob.
52 */
53int pkcs8_note_version(void *context, size_t hdrlen,
54		       unsigned char tag,
55		       const void *value, size_t vlen)
56{
57	if (vlen != 1 || ((const u8 *)value)[0] != 0) {
58		pr_warn("Unsupported PKCS#8 version\n");
59		return -EBADMSG;
60	}
61	return 0;
62}
63
64/*
65 * Note the public algorithm.
66 */
67int pkcs8_note_algo(void *context, size_t hdrlen,
68		    unsigned char tag,
69		    const void *value, size_t vlen)
70{
71	struct pkcs8_parse_context *ctx = context;
72
73	if (ctx->last_oid != OID_rsaEncryption)
74		return -ENOPKG;
75
76	ctx->pub->pkey_algo = "rsa";
77	return 0;
78}
79
80/*
81 * Note the key data of the ASN.1 blob.
82 */
83int pkcs8_note_key(void *context, size_t hdrlen,
84		   unsigned char tag,
85		   const void *value, size_t vlen)
86{
87	struct pkcs8_parse_context *ctx = context;
88
89	ctx->key = value;
90	ctx->key_size = vlen;
91	return 0;
92}
93
94/*
95 * Parse a PKCS#8 private key blob.
96 */
97static struct public_key *pkcs8_parse(const void *data, size_t datalen)
98{
99	struct pkcs8_parse_context ctx;
100	struct public_key *pub;
101	long ret;
102
103	memset(&ctx, 0, sizeof(ctx));
104
105	ret = -ENOMEM;
106	ctx.pub = kzalloc(sizeof(struct public_key), GFP_KERNEL);
107	if (!ctx.pub)
108		goto error;
109
110	ctx.data = (unsigned long)data;
111
112	/* Attempt to decode the private key */
113	ret = asn1_ber_decoder(&pkcs8_decoder, &ctx, data, datalen);
114	if (ret < 0)
115		goto error_decode;
116
117	ret = -ENOMEM;
118	pub = ctx.pub;
119	pub->key = kmemdup(ctx.key, ctx.key_size, GFP_KERNEL);
120	if (!pub->key)
121		goto error_decode;
122
123	pub->keylen = ctx.key_size;
124	pub->key_is_private = true;
125	return pub;
126
127error_decode:
128	kfree(ctx.pub);
129error:
130	return ERR_PTR(ret);
131}
132
133/*
134 * Attempt to parse a data blob for a key as a PKCS#8 private key.
135 */
136static int pkcs8_key_preparse(struct key_preparsed_payload *prep)
137{
138	struct public_key *pub;
139
140	pub = pkcs8_parse(prep->data, prep->datalen);
141	if (IS_ERR(pub))
142		return PTR_ERR(pub);
143
144	pr_devel("Cert Key Algo: %s\n", pub->pkey_algo);
145	pub->id_type = "PKCS8";
146
147	/* We're pinning the module by being linked against it */
148	__module_get(public_key_subtype.owner);
149	prep->payload.data[asym_subtype] = &public_key_subtype;
150	prep->payload.data[asym_key_ids] = NULL;
151	prep->payload.data[asym_crypto] = pub;
152	prep->payload.data[asym_auth] = NULL;
153	prep->quotalen = 100;
154	return 0;
155}
156
157static struct asymmetric_key_parser pkcs8_key_parser = {
158	.owner	= THIS_MODULE,
159	.name	= "pkcs8",
160	.parse	= pkcs8_key_preparse,
161};
162
163/*
164 * Module stuff
165 */
166static int __init pkcs8_key_init(void)
167{
168	return register_asymmetric_key_parser(&pkcs8_key_parser);
169}
170
171static void __exit pkcs8_key_exit(void)
172{
173	unregister_asymmetric_key_parser(&pkcs8_key_parser);
174}
175
176module_init(pkcs8_key_init);
177module_exit(pkcs8_key_exit);
178
179MODULE_DESCRIPTION("PKCS#8 certificate parser");
180MODULE_LICENSE("GPL");
181