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@1"; fdt = "fdt@1"; signature@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@1 { - algo = "sha1,rsa2048"; + algo = "sha256,rsa2048"; key-name-hint = "dev"; }; };