[U-Boot] [PATCH] rsa: add a more flexible way to support different hash algorithms (e.g. sha256)
andreas at oetken.name
andreas at oetken.name
Tue Nov 26 13:37:52 CET 2013
I currently need support for rsa-sha256 signatures in u-boot and found out that
the code for signatures is not very generic. Thus adding of different
hash-algorithms for rsa-signatures is not easy to do without copy-pasting the
rsa-code. I attached a patch for how I think it could be better and included
support for rsa-sha256. This is a fast first shot.
diff --git a/common/image-sig.c b/common/image-sig.c
index 973b06d..db15cb6 100644
--- a/common/image-sig.c
+++ b/common/image-sig.c
@@ -14,15 +14,48 @@ DECLARE_GLOBAL_DATA_PTR;
#endif /* !USE_HOSTCC*/
#include <image.h>
#include <rsa.h>
+#include <rsa-checksum.h>
#define IMAGE_MAX_HASHED_NODES 100
+
+struct checksum_algo checksum_algos[] = {
+ {
+ "sha1",
+ SHA1_SUM_LEN,
+#if IMAGE_ENABLE_SIGN
+ EVP_sha1,
+#else
+ sha1_calculate,
+ padding_sha1_rsa2048,
+#endif
+ },
+ {
+ "sha256",
+ SHA256_SUM_LEN,
+#if IMAGE_ENABLE_SIGN
+ EVP_sha256,
+#else
+ sha256_calculate,
+ padding_sha256_rsa2048,
+#endif
+ }
+};
+
struct image_sig_algo image_sig_algos[] = {
{
"sha1,rsa2048",
rsa_sign,
rsa_add_verify_data,
rsa_verify,
+ &checksum_algos[0],
+ },
+ {
+ "sha256,rsa2048",
+ rsa_sign,
+ rsa_add_verify_data,
+ rsa_verify,
+ &checksum_algos[1],
}
};
diff --git a/include/image.h b/include/image.h
index ee6eb8d..47268aa 100644
--- a/include/image.h
+++ b/include/image.h
@@ -822,7 +822,8 @@ int calculate_hash(const void *data, int data_len, const
char *algo,
# ifdef USE_HOSTCC
# define IMAGE_ENABLE_SIGN 1
# define IMAGE_ENABLE_VERIFY 0
-#else
+# include <openssl/evp.h>
+# else
# define IMAGE_ENABLE_SIGN 0
# define IMAGE_ENABLE_VERIFY 1
# endif
@@ -861,6 +862,22 @@ struct image_region {
int size;
};
+#if IMAGE_ENABLE_VERIFY
+# include <rsa-checksum.h>
+#endif
+struct checksum_algo {
+ const char *name;
+ const int checksum_len;
+#if IMAGE_ENABLE_SIGN
+ EVP_MD *(*calculate)(void);
+#else
+#if IMAGE_ENABLE_VERIFY
+ void (*calculate)(const struct image_region region[], int region_count,
uint8_t * checksum);
+ const uint8_t * rsa_padding;
+#endif
+#endif
+};
+
struct image_sig_algo {
const char *name; /* Name of algorithm */
@@ -911,6 +928,10 @@ struct image_sig_algo {
int (*verify)(struct image_sign_info *info,
const struct image_region region[], int region_count,
uint8_t *sig, uint sig_len);
+
+ /* pointer to checksum algorithm */
+ struct checksum_algo * checksum;
+
};
/**
diff --git a/include/rsa-checksum.h b/include/rsa-checksum.h
new file mode 100644
index 0000000..a318538
--- /dev/null
+++ b/include/rsa-checksum.h
@@ -0,0 +1,23 @@
+/*
+ * Copyright (c) 2013, Andreas Oetken.
+ *
+ * SPDX-License-Identifier: GPL-2.0+
+ */
+
+#ifndef _RSA_CHECKSUM_H
+#define _RSA_CHECKSUM_H
+
+#include <errno.h>
+#include <image.h>
+#include <sha1.h>
+#include <sha256.h>
+
+#if IMAGE_ENABLE_VERIFY
+extern const uint8_t padding_sha256_rsa2048[];
+extern const uint8_t padding_sha1_rsa2048[];
+
+void sha256_calculate(const struct image_region region[], int region_count,
uint8_t * checksum);
+void sha1_calculate(const struct image_region region[], int region_count,
uint8_t * checksum);
+#endif
+
+#endif
diff --git a/include/rsa.h b/include/rsa.h
index add4c78..3f6bb2c 100644
--- a/include/rsa.h
+++ b/include/rsa.h
@@ -15,6 +15,22 @@
#include <errno.h>
#include <image.h>
+
+/**
+ * struct rsa_public_key - holder for a public key
+ *
+ * An RSA public key consists of a modulus (typically called N), the inverse
+ * and R^2, where R is 2^(# key bits).
+ */
+
+struct rsa_public_key {
+ uint len; /* Length of modulus[] in number of uint32_t */
+ uint32_t n0inv; /* -1 / modulus[0] mod 2^32 */
+ uint32_t *modulus; /* modulus as little endian array */
+ uint32_t *rr; /* R^2 as little endian array */
+};
+
+
#if IMAGE_ENABLE_SIGN
/**
* sign() - calculate and return signature for given input data
diff --git a/lib/rsa/Makefile b/lib/rsa/Makefile
index decd6e5..bf18cdc 100644
--- a/lib/rsa/Makefile
+++ b/lib/rsa/Makefile
@@ -12,7 +12,7 @@ include $(TOPDIR)/config.mk
LIB = $(obj)librsa.o
ifdef CONFIG_FIT_SIGNATURE
-COBJS-$(CONFIG_RSA) += rsa-verify.o
+COBJS-$(CONFIG_RSA) += rsa-verify.o rsa-checksum.o
endif
COBJS := $(sort $(COBJS-y))
diff --git a/lib/rsa/rsa-checksum.c b/lib/rsa/rsa-checksum.c
new file mode 100644
index 0000000..fca065c
--- /dev/null
+++ b/lib/rsa/rsa-checksum.c
@@ -0,0 +1,77 @@
+/*
+ * Copyright (c) 2013, Andreas Oetken.
+ *
+ * SPDX-License-Identifier: GPL-2.0+
+ */
+
+#include <common.h>
+#include <fdtdec.h>
+#include <rsa.h>
+#include <sha1.h>
+#include <sha256.h>
+#include <asm/byteorder.h>
+#include <asm/errno.h>
+#include <asm/unaligned.h>
+
+#define RSA2048_BYTES 256
+
+const uint8_t padding_sha256_rsa2048[RSA2048_BYTES - SHA256_SUM_LEN] = {
+0x00, 0x01, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x00, 0x30, 0x31, 0x30,
0x0d, 0x06, 0x09, 0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x01, 0x05,
0x00, 0x04, 0x20
+};
+
+const uint8_t padding_sha1_rsa2048[RSA2048_BYTES - SHA1_SUM_LEN] = {
+ 0x00, 0x01, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+ 0xff, 0xff, 0xff, 0xff, 0x00, 0x30, 0x21, 0x30,
+ 0x09, 0x06, 0x05, 0x2b, 0x0e, 0x03, 0x02, 0x1a,
+ 0x05, 0x00, 0x04, 0x14
+};
+
+
+void sha1_calculate(const struct image_region region[], int region_count,
uint8_t * checksum){
+ sha1_context ctx;
+ uint32_t i;
+ i = 0;
+
+ sha1_starts(&ctx);
+ for (i = 0; i < region_count; i++)
+ sha1_update(&ctx, region[i].data, region[i].size);
+ sha1_finish(&ctx, checksum);
+}
+
+void sha256_calculate(const struct image_region region[], int region_count,
uint8_t * checksum){
+ sha256_context ctx;
+ uint32_t i;
+ i = 0;
+
+ sha256_starts(&ctx);
+ for (i = 0; i < region_count; i++)
+ sha256_update(&ctx, region[i].data, region[i].size);
+ sha256_finish(&ctx, checksum);
+}
+
diff --git a/lib/rsa/rsa-sign.c b/lib/rsa/rsa-sign.c
index 549130e..9886e15 100644
--- a/lib/rsa/rsa-sign.c
+++ b/lib/rsa/rsa-sign.c
@@ -159,7 +159,7 @@ static void rsa_remove(void)
EVP_cleanup();
}
-static int rsa_sign_with_key(RSA *rsa, const struct image_region region[],
+static int rsa_sign_with_key(RSA *rsa, struct checksum_algo * checksum_algo,
const struct image_region region[],
int region_count, uint8_t **sigp, uint *sig_size)
{
EVP_PKEY *key;
@@ -192,7 +192,7 @@ static int rsa_sign_with_key(RSA *rsa, const struct
image_region region[],
goto err_create;
}
EVP_MD_CTX_init(context);
- if (!EVP_SignInit(context, EVP_sha1())) {
+ if (!EVP_SignInit(context, checksum_algo->calculate())) {
ret = rsa_err("Signer setup failed");
goto err_sign;
}
@@ -242,7 +242,7 @@ int rsa_sign(struct image_sign_info *info,
ret = rsa_get_priv_key(info->keydir, info->keyname, &rsa);
if (ret)
goto err_priv;
- ret = rsa_sign_with_key(rsa, region, region_count, sigp, sig_len);
+ ret = rsa_sign_with_key(rsa, info->algo->checksum, region, region_count,
sigp, sig_len);
if (ret)
goto err_sign;
diff --git a/lib/rsa/rsa-verify.c b/lib/rsa/rsa-verify.c
index 02cc4e3..6099418 100644
--- a/lib/rsa/rsa-verify.c
+++ b/lib/rsa/rsa-verify.c
@@ -7,24 +7,10 @@
#include <common.h>
#include <fdtdec.h>
#include <rsa.h>
-#include <sha1.h>
#include <asm/byteorder.h>
#include <asm/errno.h>
#include <asm/unaligned.h>
-/**
- * struct rsa_public_key - holder for a public key
- *
- * An RSA public key consists of a modulus (typically called N), the inverse
- * and R^2, where R is 2^(# key bits).
- */
-struct rsa_public_key {
- uint len; /* Length of modulus[] in number of uint32_t */
- uint32_t n0inv; /* -1 / modulus[0] mod 2^32 */
- uint32_t *modulus; /* modulus as little endian array */
- uint32_t *rr; /* R^2 as little endian array */
-};
-
#define UINT64_MULT32(v, multby) (((uint64_t)(v)) * ((uint32_t)(multby)))
#define RSA2048_BYTES (2048 / 8)
@@ -36,38 +22,6 @@ struct rsa_public_key {
/* This is the maximum signature length that we support, in bits */
#define RSA_MAX_SIG_BITS 2048
-static const uint8_t padding_sha1_rsa2048[RSA2048_BYTES - SHA1_SUM_LEN] = {
- 0x00, 0x01, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
- 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
- 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
- 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
- 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
- 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
- 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
- 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
- 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
- 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
- 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
- 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
- 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
- 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
- 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
- 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
- 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
- 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
- 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
- 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
- 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
- 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
- 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
- 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
- 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
- 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
- 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
- 0xff, 0xff, 0xff, 0xff, 0x00, 0x30, 0x21, 0x30,
- 0x09, 0x06, 0x05, 0x2b, 0x0e, 0x03, 0x02, 0x1a,
- 0x05, 0x00, 0x04, 0x14
-};
/**
* subtract_modulus() - subtract modulus from the given value
@@ -209,7 +163,7 @@ static int pow_mod(const struct rsa_public_key *key,
uint32_t *inout)
}
static int rsa_verify_key(const struct rsa_public_key *key, const uint8_t *sig,
- const uint32_t sig_len, const uint8_t *hash)
+ const uint32_t sig_len, const uint8_t *hash, struct checksum_algo *
algo)
{
const uint8_t *padding;
int pad_len;
@@ -223,6 +177,8 @@ static int rsa_verify_key(const struct rsa_public_key *key,
const uint8_t *sig,
return -EINVAL;
}
+ debug("Checksum algorithm: %s", algo->name);
+
/* Sanity check for stack size */
if (sig_len > RSA_MAX_SIG_BITS / 8) {
debug("Signature length %u exceeds maximum %d\n", sig_len,
@@ -239,8 +195,8 @@ static int rsa_verify_key(const struct rsa_public_key *key,
const uint8_t *sig,
return ret;
/* Determine padding to use depending on the signature type. */
- padding = padding_sha1_rsa2048;
- pad_len = RSA2048_BYTES - SHA1_SUM_LEN;
+ padding = algo->rsa_padding;
+ pad_len = RSA2048_BYTES - algo->checksum_len;
/* Check pkcs1.5 padding bytes. */
if (memcmp(buf, padding, pad_len)) {
@@ -309,7 +265,7 @@ static int rsa_verify_with_keynode(struct image_sign_info
*info,
}
debug("key length %d\n", key.len);
- ret = rsa_verify_key(&key, sig, sig_len, hash);
+ ret = rsa_verify_key(&key, sig, sig_len, hash, info->algo->checksum);
if (ret) {
printf("%s: RSA failed to verify: %d\n", __func__, ret);
return ret;
@@ -323,12 +279,18 @@ int rsa_verify(struct image_sign_info *info,
uint8_t *sig, uint sig_len)
{
const void *blob = info->fdt_blob;
- uint8_t hash[SHA1_SUM_LEN];
+ /* Reserve memory for maximum checksum-length */
+ uint8_t hash[RSA2048_BYTES];
int ndepth, noffset;
int sig_node, node;
char name[100];
- sha1_context ctx;
- int ret, i;
+ int ret;
+
+ /* Verify that the checksum-length does not exceed the rsa-signature-length
*/
+ if(info->algo->checksum->checksum_len > RSA2048_BYTES){
+ debug("%s: invlaid checksum-algorithm %s for RSA2048\n", __func__,
info->algo->checksum->name);
+ return -EINVAL;
+ }
sig_node = fdt_subnode_offset(blob, 0, FIT_SIG_NODENAME);
if (sig_node < 0) {
@@ -336,10 +298,8 @@ int rsa_verify(struct image_sign_info *info,
return -ENOENT;
}
- sha1_starts(&ctx);
- for (i = 0; i < region_count; i++)
- sha1_update(&ctx, region[i].data, region[i].size);
- sha1_finish(&ctx, hash);
+ /* Calculate checksum with checksum-algorithm */
+ info->algo->checksum->calculate(region, region_count, hash);
/* See if we must use a particular key */
if (info->required_keynode != -1) {
diff --git a/test/vboot/sign-configs.its b/test/vboot/sign-configs.its
index db2ed79..5b315f3 100644
--- a/test/vboot/sign-configs.its
+++ b/test/vboot/sign-configs.its
@@ -36,7 +36,7 @@
kernel = "kernel at 1";
fdt = "fdt at 1";
signature at 1 {
- algo = "sha1,rsa2048";
+ algo = "sha256,rsa2048";
key-name-hint = "dev";
sign-images = "fdt", "kernel";
};
diff --git a/test/vboot/sign-images.its b/test/vboot/sign-images.its
index f69326a..e2b0446 100644
--- a/test/vboot/sign-images.its
+++ b/test/vboot/sign-images.its
@@ -27,7 +27,7 @@
compression = "none";
fdt-version = <1>;
signature at 1 {
- algo = "sha1,rsa2048";
+ algo = "sha256,rsa2048";
key-name-hint = "dev";
};
};
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