]>
git.ipfire.org Git - people/ms/u-boot.git/blob - lib/rsa/rsa-verify.c
2 * Copyright (c) 2013, Google Inc.
4 * SPDX-License-Identifier: GPL-2.0+
10 #include <asm/types.h>
11 #include <asm/byteorder.h>
12 #include <asm/errno.h>
13 #include <asm/types.h>
14 #include <asm/unaligned.h>
19 #include <fdt_support.h>
21 #include <u-boot/rsa-mod-exp.h>
22 #include <u-boot/rsa.h>
24 /* Default public exponent for backward compatibility */
25 #define RSA_DEFAULT_PUBEXP 65537
28 * rsa_verify_key() - Verify a signature against some data using RSA Key
30 * Verify a RSA PKCS1.5 signature against an expected hash using
31 * the RSA Key properties in prop structure.
33 * @prop: Specifies key
35 * @sig_len: Number of bytes in signature
36 * @hash: Pointer to the expected hash
37 * @algo: Checksum algo structure having information on RSA padding etc.
38 * @return 0 if verified, -ve on error
40 static int rsa_verify_key(struct key_prop
*prop
, const uint8_t *sig
,
41 const uint32_t sig_len
, const uint8_t *hash
,
42 struct checksum_algo
*algo
)
44 const uint8_t *padding
;
47 #if !defined(USE_HOSTCC)
48 struct udevice
*mod_exp_dev
;
51 if (!prop
|| !sig
|| !hash
|| !algo
)
54 if (sig_len
!= (prop
->num_bits
/ 8)) {
55 debug("Signature is of incorrect length %d\n", sig_len
);
59 debug("Checksum algorithm: %s", algo
->name
);
61 /* Sanity check for stack size */
62 if (sig_len
> RSA_MAX_SIG_BITS
/ 8) {
63 debug("Signature length %u exceeds maximum %d\n", sig_len
,
64 RSA_MAX_SIG_BITS
/ 8);
70 #if !defined(USE_HOSTCC)
71 ret
= uclass_get_device(UCLASS_MOD_EXP
, 0, &mod_exp_dev
);
73 printf("RSA: Can't find Modular Exp implementation\n");
77 ret
= rsa_mod_exp(mod_exp_dev
, sig
, sig_len
, prop
, buf
);
79 ret
= rsa_mod_exp_sw(sig
, sig_len
, prop
, buf
);
82 debug("Error in Modular exponentation\n");
86 padding
= algo
->rsa_padding
;
87 pad_len
= algo
->pad_len
- algo
->checksum_len
;
89 /* Check pkcs1.5 padding bytes. */
90 if (memcmp(buf
, padding
, pad_len
)) {
91 debug("In RSAVerify(): Padding check failed!\n");
96 if (memcmp((uint8_t *)buf
+ pad_len
, hash
, sig_len
- pad_len
)) {
97 debug("In RSAVerify(): Hash check failed!\n");
105 * rsa_verify_with_keynode() - Verify a signature against some data using
106 * information in node with prperties of RSA Key like modulus, exponent etc.
108 * Parse sign-node and fill a key_prop structure with properties of the
109 * key. Verify a RSA PKCS1.5 signature against an expected hash using
110 * the properties parsed
112 * @info: Specifies key and FIT information
113 * @hash: Pointer to the expected hash
115 * @sig_len: Number of bytes in signature
116 * @node: Node having the RSA Key properties
117 * @return 0 if verified, -ve on error
119 static int rsa_verify_with_keynode(struct image_sign_info
*info
,
120 const void *hash
, uint8_t *sig
,
121 uint sig_len
, int node
)
123 const void *blob
= info
->fdt_blob
;
124 struct key_prop prop
;
129 debug("%s: Skipping invalid node", __func__
);
133 prop
.num_bits
= fdtdec_get_int(blob
, node
, "rsa,num-bits", 0);
135 prop
.n0inv
= fdtdec_get_int(blob
, node
, "rsa,n0-inverse", 0);
137 prop
.public_exponent
= fdt_getprop(blob
, node
, "rsa,exponent", &length
);
138 if (!prop
.public_exponent
|| length
< sizeof(uint64_t))
139 prop
.public_exponent
= NULL
;
141 prop
.exp_len
= sizeof(uint64_t);
143 prop
.modulus
= fdt_getprop(blob
, node
, "rsa,modulus", NULL
);
145 prop
.rr
= fdt_getprop(blob
, node
, "rsa,r-squared", NULL
);
147 if (!prop
.num_bits
|| !prop
.modulus
) {
148 debug("%s: Missing RSA key info", __func__
);
152 ret
= rsa_verify_key(&prop
, sig
, sig_len
, hash
, info
->algo
->checksum
);
157 int rsa_verify(struct image_sign_info
*info
,
158 const struct image_region region
[], int region_count
,
159 uint8_t *sig
, uint sig_len
)
161 const void *blob
= info
->fdt_blob
;
162 /* Reserve memory for maximum checksum-length */
163 uint8_t hash
[info
->algo
->checksum
->pad_len
];
170 * Verify that the checksum-length does not exceed the
171 * rsa-signature-length
173 if (info
->algo
->checksum
->checksum_len
>
174 info
->algo
->checksum
->pad_len
) {
175 debug("%s: invlaid checksum-algorithm %s for %s\n",
176 __func__
, info
->algo
->checksum
->name
, info
->algo
->name
);
180 sig_node
= fdt_subnode_offset(blob
, 0, FIT_SIG_NODENAME
);
182 debug("%s: No signature node found\n", __func__
);
186 /* Calculate checksum with checksum-algorithm */
187 ret
= info
->algo
->checksum
->calculate(info
->algo
->checksum
->name
,
188 region
, region_count
, hash
);
190 debug("%s: Error in checksum calculation\n", __func__
);
194 /* See if we must use a particular key */
195 if (info
->required_keynode
!= -1) {
196 ret
= rsa_verify_with_keynode(info
, hash
, sig
, sig_len
,
197 info
->required_keynode
);
202 /* Look for a key that matches our hint */
203 snprintf(name
, sizeof(name
), "key-%s", info
->keyname
);
204 node
= fdt_subnode_offset(blob
, sig_node
, name
);
205 ret
= rsa_verify_with_keynode(info
, hash
, sig
, sig_len
, node
);
209 /* No luck, so try each of the keys in turn */
210 for (ndepth
= 0, noffset
= fdt_next_node(info
->fit
, sig_node
, &ndepth
);
211 (noffset
>= 0) && (ndepth
> 0);
212 noffset
= fdt_next_node(info
->fit
, noffset
, &ndepth
)) {
213 if (ndepth
== 1 && noffset
!= node
) {
214 ret
= rsa_verify_with_keynode(info
, hash
, sig
, sig_len
,