[U-Boot] [PATCH v3 03/12] image: Add RSA support for image signing
Simon Glass
sjg at chromium.org
Fri Jun 14 00:10:02 CEST 2013
RSA provides a public key encryption facility which is ideal for image
signing and verification.
Images are signed using a private key by mkimage. Then at run-time, the
images are verified using a private key.
This implementation uses openssl for the host part (mkimage). To avoid
bringing large libraries into the U-Boot binary, the RSA public key
is encoded using a simple numeric representation in the device tree.
Signed-off-by: Simon Glass <sjg at chromium.org>
---
Changes in v3: None
Changes in v2:
- Add sanity checks on key sizes in RSA (improves security)
- Avoid using malloc in RSA routines (for smaller SPL code size)
- Build signing support unconditionally in mkimage
- Fix checkpatch checks about parenthesis alignment
- Fix spelling of multiply in rsa-verify.c
- Only build RSA support into mkimage if CONFIG_RSA is defined
- Support RSA library version without ERR_remove_thread_state()
Makefile | 1 +
README | 10 ++
common/image-sig.c | 7 +
config.mk | 1 +
include/rsa.h | 108 ++++++++++++
lib/rsa/Makefile | 48 ++++++
lib/rsa/rsa-sign.c | 460 +++++++++++++++++++++++++++++++++++++++++++++++++++
lib/rsa/rsa-verify.c | 385 ++++++++++++++++++++++++++++++++++++++++++
tools/Makefile | 13 +-
9 files changed, 1031 insertions(+), 2 deletions(-)
create mode 100644 include/rsa.h
create mode 100644 lib/rsa/Makefile
create mode 100644 lib/rsa/rsa-sign.c
create mode 100644 lib/rsa/rsa-verify.c
diff --git a/Makefile b/Makefile
index eb751f4..90f2bb9 100644
--- a/Makefile
+++ b/Makefile
@@ -247,6 +247,7 @@ OBJS := $(addprefix $(obj),$(OBJS))
HAVE_VENDOR_COMMON_LIB = $(if $(wildcard board/$(VENDOR)/common/Makefile),y,n)
LIBS-y += lib/libgeneric.o
+LIBS-y += lib/rsa/librsa.o
LIBS-y += lib/lzma/liblzma.o
LIBS-y += lib/lzo/liblzo.o
LIBS-y += lib/zlib/libz.o
diff --git a/README b/README
index 3e586c3..f91e431 100644
--- a/README
+++ b/README
@@ -2557,6 +2557,16 @@ CBFS (Coreboot Filesystem) support
Note: There is also a sha1sum command, which should perhaps
be deprecated in favour of 'hash sha1'.
+- Signing support:
+ CONFIG_RSA
+
+ This enables the RSA algorithm used for FIT image verification
+ in U-Boot. See doc/uImage/signature for more information.
+
+ The signing part is build into mkimage regardless of this
+ option.
+
+
- Show boot progress:
CONFIG_SHOW_BOOT_PROGRESS
diff --git a/common/image-sig.c b/common/image-sig.c
index 9b222da..9928bfc 100644
--- a/common/image-sig.c
+++ b/common/image-sig.c
@@ -27,8 +27,15 @@ DECLARE_GLOBAL_DATA_PTR;
#endif /* !USE_HOSTCC*/
#include <errno.h>
#include <image.h>
+#include <rsa.h>
struct image_sig_algo image_sig_algos[] = {
+ {
+ "sha1,rsa2048",
+ rsa_sign,
+ rsa_add_verify_data,
+ rsa_verify,
+ }
};
struct image_sig_algo *image_get_sig_algo(const char *name)
diff --git a/config.mk b/config.mk
index 9003268..a5e26e3 100644
--- a/config.mk
+++ b/config.mk
@@ -96,6 +96,7 @@ HOSTCFLAGS += $(call os_x_before, 10, 4, "-traditional-cpp")
HOSTLDFLAGS += $(call os_x_before, 10, 5, "-multiply_defined suppress")
else
HOSTCC = gcc
+HOSTLIBS += -lssl -lcrypto
endif
ifeq ($(HOSTOS),cygwin)
diff --git a/include/rsa.h b/include/rsa.h
new file mode 100644
index 0000000..a5dd676
--- /dev/null
+++ b/include/rsa.h
@@ -0,0 +1,108 @@
+/*
+ * Copyright (c) 2013, Google Inc.
+ *
+ * (C) Copyright 2008 Semihalf
+ *
+ * (C) Copyright 2000-2006
+ * Wolfgang Denk, DENX Software Engineering, wd at denx.de.
+ *
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+
+#ifndef _RSA_H
+#define _RSA_H
+
+#include <errno.h>
+#include <image.h>
+
+#if IMAGE_ENABLE_SIGN
+/**
+ * sign() - calculate and return signature for given input data
+ *
+ * @info: Specifies key and FIT information
+ * @data: Pointer to the input data
+ * @data_len: Data length
+ * @sigp: Set to an allocated buffer holding the signature
+ * @sig_len: Set to length of the calculated hash
+ *
+ * This computes input data signature according to selected algorithm.
+ * Resulting signature value is placed in an allocated buffer, the
+ * pointer is returned as *sigp. The length of the calculated
+ * signature is returned via the sig_len pointer argument. The caller
+ * should free *sigp.
+ *
+ * @return: 0, on success, -ve on error
+ */
+int rsa_sign(struct image_sign_info *info,
+ const struct image_region region[],
+ int region_count, uint8_t **sigp, uint *sig_len);
+
+/**
+ * add_verify_data() - Add verification information to FDT
+ *
+ * Add public key information to the FDT node, suitable for
+ * verification at run-time. The information added depends on the
+ * algorithm being used.
+ *
+ * @info: Specifies key and FIT information
+ * @keydest: Destination FDT blob for public key data
+ * @return: 0, on success, -ve on error
+*/
+int rsa_add_verify_data(struct image_sign_info *info, void *keydest);
+#else
+static inline int rsa_sign(struct image_sign_info *info,
+ const struct image_region region[], int region_count,
+ uint8_t **sigp, uint *sig_len)
+{
+ return -ENXIO;
+}
+
+static inline int rsa_add_verify_data(struct image_sign_info *info,
+ void *keydest)
+{
+ return -ENXIO;
+}
+#endif
+
+#if IMAGE_ENABLE_VERIFY
+/**
+ * rsa_verify() - Verify a signature against some data
+ *
+ * Verify a RSA PKCS1.5 signature against an expected hash.
+ *
+ * @info: Specifies key and FIT information
+ * @data: Pointer to the input data
+ * @data_len: Data length
+ * @sig: Signature
+ * @sig_len: Number of bytes in signature
+ * @return 0 if verified, -ve on error
+ */
+int rsa_verify(struct image_sign_info *info,
+ const struct image_region region[], int region_count,
+ uint8_t *sig, uint sig_len);
+#else
+static inline int rsa_verify(struct image_sign_info *info,
+ const struct image_region region[], int region_count,
+ uint8_t *sig, uint sig_len)
+{
+ return -ENXIO;
+}
+#endif
+
+#endif
diff --git a/lib/rsa/Makefile b/lib/rsa/Makefile
new file mode 100644
index 0000000..9eb3e40
--- /dev/null
+++ b/lib/rsa/Makefile
@@ -0,0 +1,48 @@
+#
+# Copyright (c) 2013, Google Inc.
+#
+# (C) Copyright 2000-2007
+# Wolfgang Denk, DENX Software Engineering, wd at denx.de.
+#
+# See file CREDITS for list of people who contributed to this
+# project.
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License as
+# published by the Free Software Foundation; either version 2 of
+# the License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+# MA 02111-1307 USA
+#
+
+include $(TOPDIR)/config.mk
+
+LIB = $(obj)librsa.o
+
+ifdef CONFIG_FIT_SIGNATURE
+COBJS-$(CONFIG_RSA) += rsa-verify.o
+endif
+
+COBJS := $(sort $(COBJS-y))
+SRCS := $(COBJS:.o=.c)
+OBJS := $(addprefix $(obj),$(COBJS))
+
+$(LIB): $(obj).depend $(OBJS)
+ $(call cmd_link_o_target, $(OBJS))
+
+#########################################################################
+
+# defines $(obj).depend target
+include $(SRCTREE)/rules.mk
+
+sinclude $(obj).depend
+
+#########################################################################
diff --git a/lib/rsa/rsa-sign.c b/lib/rsa/rsa-sign.c
new file mode 100644
index 0000000..a75ae24
--- /dev/null
+++ b/lib/rsa/rsa-sign.c
@@ -0,0 +1,460 @@
+/*
+ * Copyright (c) 2013, Google Inc.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+
+#include "mkimage.h"
+#include <stdio.h>
+#include <string.h>
+#include <error.h>
+#include <image.h>
+#include <time.h>
+#include <openssl/rsa.h>
+#include <openssl/pem.h>
+#include <openssl/err.h>
+#include <openssl/ssl.h>
+#include <openssl/evp.h>
+
+#if OPENSSL_VERSION_NUMBER >= 0x10000000L
+#define HAVE_ERR_REMOVE_THREAD_STATE
+#endif
+
+static int rsa_err(const char *msg)
+{
+ unsigned long sslErr = ERR_get_error();
+
+ fprintf(stderr, "%s", msg);
+ fprintf(stderr, ": %s\n",
+ ERR_error_string(sslErr, 0));
+
+ return -1;
+}
+
+/**
+ * rsa_get_pub_key() - read a public key from a .crt file
+ *
+ * @keydir: Directory containins the key
+ * @name Name of key file (will have a .crt extension)
+ * @rsap Returns RSA object, or NULL on failure
+ * @return 0 if ok, -ve on error (in which case *rsap will be set to NULL)
+ */
+static int rsa_get_pub_key(const char *keydir, const char *name, RSA **rsap)
+{
+ char path[1024];
+ EVP_PKEY *key;
+ X509 *cert;
+ RSA *rsa;
+ FILE *f;
+ int ret;
+
+ *rsap = NULL;
+ snprintf(path, sizeof(path), "%s/%s.crt", keydir, name);
+ f = fopen(path, "r");
+ if (!f) {
+ fprintf(stderr, "Couldn't open RSA certificate: '%s': %s\n",
+ path, strerror(errno));
+ return -EACCES;
+ }
+
+ /* Read the certificate */
+ cert = NULL;
+ if (!PEM_read_X509(f, &cert, NULL, NULL)) {
+ rsa_err("Couldn't read certificate");
+ ret = -EINVAL;
+ goto err_cert;
+ }
+
+ /* Get the public key from the certificate. */
+ key = X509_get_pubkey(cert);
+ if (!key) {
+ rsa_err("Couldn't read public key\n");
+ ret = -EINVAL;
+ goto err_pubkey;
+ }
+
+ /* Convert to a RSA_style key. */
+ rsa = EVP_PKEY_get1_RSA(key);
+ if (!rsa) {
+ rsa_err("Couldn't convert to a RSA style key");
+ goto err_rsa;
+ }
+ fclose(f);
+ EVP_PKEY_free(key);
+ X509_free(cert);
+ *rsap = rsa;
+
+ return 0;
+
+err_rsa:
+ EVP_PKEY_free(key);
+err_pubkey:
+ X509_free(cert);
+err_cert:
+ fclose(f);
+ return ret;
+}
+
+/**
+ * rsa_get_priv_key() - read a private key from a .key file
+ *
+ * @keydir: Directory containins the key
+ * @name Name of key file (will have a .key extension)
+ * @rsap Returns RSA object, or NULL on failure
+ * @return 0 if ok, -ve on error (in which case *rsap will be set to NULL)
+ */
+static int rsa_get_priv_key(const char *keydir, const char *name, RSA **rsap)
+{
+ char path[1024];
+ RSA *rsa;
+ FILE *f;
+
+ *rsap = NULL;
+ snprintf(path, sizeof(path), "%s/%s.key", keydir, name);
+ f = fopen(path, "r");
+ if (!f) {
+ fprintf(stderr, "Couldn't open RSA private key: '%s': %s\n",
+ path, strerror(errno));
+ return -ENOENT;
+ }
+
+ rsa = PEM_read_RSAPrivateKey(f, 0, NULL, path);
+ if (!rsa) {
+ rsa_err("Failure reading private key");
+ fclose(f);
+ return -EPROTO;
+ }
+ fclose(f);
+ *rsap = rsa;
+
+ return 0;
+}
+
+static int rsa_init(void)
+{
+ int ret;
+
+ ret = SSL_library_init();
+ if (!ret) {
+ fprintf(stderr, "Failure to init SSL library\n");
+ return -1;
+ }
+ SSL_load_error_strings();
+
+ OpenSSL_add_all_algorithms();
+ OpenSSL_add_all_digests();
+ OpenSSL_add_all_ciphers();
+
+ return 0;
+}
+
+static void rsa_remove(void)
+{
+ CRYPTO_cleanup_all_ex_data();
+ ERR_free_strings();
+#ifdef HAVE_ERR_REMOVE_THREAD_STATE
+ ERR_remove_thread_state(NULL);
+#else
+ ERR_remove_state(0);
+#endif
+ EVP_cleanup();
+}
+
+static int rsa_sign_with_key(RSA *rsa, const struct image_region region[],
+ int region_count, uint8_t **sigp, uint *sig_size)
+{
+ EVP_PKEY *key;
+ EVP_MD_CTX *context;
+ int size, ret = 0;
+ uint8_t *sig;
+ int i;
+
+ key = EVP_PKEY_new();
+ if (!key)
+ return rsa_err("EVP_PKEY object creation failed");
+
+ if (!EVP_PKEY_set1_RSA(key, rsa)) {
+ ret = rsa_err("EVP key setup failed");
+ goto err_set;
+ }
+
+ size = EVP_PKEY_size(key);
+ sig = malloc(size);
+ if (!sig) {
+ fprintf(stderr, "Out of memory for signature (%d bytes)\n",
+ size);
+ ret = -ENOMEM;
+ goto err_alloc;
+ }
+
+ context = EVP_MD_CTX_create();
+ if (!context) {
+ ret = rsa_err("EVP context creation failed");
+ goto err_create;
+ }
+ EVP_MD_CTX_init(context);
+ if (!EVP_SignInit(context, EVP_sha1())) {
+ ret = rsa_err("Signer setup failed");
+ goto err_sign;
+ }
+
+ for (i = 0; i < region_count; i++) {
+ if (!EVP_SignUpdate(context, region[i].data, region[i].size)) {
+ ret = rsa_err("Signing data failed");
+ goto err_sign;
+ }
+ }
+
+ if (!EVP_SignFinal(context, sig, sig_size, key)) {
+ ret = rsa_err("Could not obtain signature");
+ goto err_sign;
+ }
+ EVP_MD_CTX_cleanup(context);
+ EVP_MD_CTX_destroy(context);
+ EVP_PKEY_free(key);
+
+ debug("Got signature: %d bytes, expected %d\n", *sig_size, size);
+ *sigp = sig;
+ *sig_size = size;
+
+ return 0;
+
+err_sign:
+ EVP_MD_CTX_destroy(context);
+err_create:
+ free(sig);
+err_alloc:
+err_set:
+ EVP_PKEY_free(key);
+ return ret;
+}
+
+int rsa_sign(struct image_sign_info *info,
+ const struct image_region region[], int region_count,
+ uint8_t **sigp, uint *sig_len)
+{
+ RSA *rsa;
+ int ret;
+
+ ret = rsa_init();
+ if (ret)
+ return ret;
+
+ 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);
+ if (ret)
+ goto err_sign;
+
+ RSA_free(rsa);
+ rsa_remove();
+
+ return ret;
+
+err_sign:
+ RSA_free(rsa);
+err_priv:
+ rsa_remove();
+ return ret;
+}
+
+/*
+ * rsa_get_params(): - Get the important parameters of an RSA public key
+ */
+int rsa_get_params(RSA *key, uint32_t *n0_invp, BIGNUM **modulusp,
+ BIGNUM **r_squaredp)
+{
+ BIGNUM *big1, *big2, *big32, *big2_32;
+ BIGNUM *n, *r, *r_squared, *tmp;
+ BN_CTX *bn_ctx = BN_CTX_new();
+ int ret = 0;
+
+ /* Initialize BIGNUMs */
+ big1 = BN_new();
+ big2 = BN_new();
+ big32 = BN_new();
+ r = BN_new();
+ r_squared = BN_new();
+ tmp = BN_new();
+ big2_32 = BN_new();
+ n = BN_new();
+ if (!big1 || !big2 || !big32 || !r || !r_squared || !tmp || !big2_32 ||
+ !n) {
+ fprintf(stderr, "Out of memory (bignum)\n");
+ return -ENOMEM;
+ }
+
+ if (!BN_copy(n, key->n) || !BN_set_word(big1, 1L) ||
+ !BN_set_word(big2, 2L) || !BN_set_word(big32, 32L))
+ ret = -1;
+
+ /* big2_32 = 2^32 */
+ if (!BN_exp(big2_32, big2, big32, bn_ctx))
+ ret = -1;
+
+ /* Calculate n0_inv = -1 / n[0] mod 2^32 */
+ if (!BN_mod_inverse(tmp, n, big2_32, bn_ctx) ||
+ !BN_sub(tmp, big2_32, tmp))
+ ret = -1;
+ *n0_invp = BN_get_word(tmp);
+
+ /* Calculate R = 2^(# of key bits) */
+ if (!BN_set_word(tmp, BN_num_bits(n)) ||
+ !BN_exp(r, big2, tmp, bn_ctx))
+ ret = -1;
+
+ /* Calculate r_squared = R^2 mod n */
+ if (!BN_copy(r_squared, r) ||
+ !BN_mul(tmp, r_squared, r, bn_ctx) ||
+ !BN_mod(r_squared, tmp, n, bn_ctx))
+ ret = -1;
+
+ *modulusp = n;
+ *r_squaredp = r_squared;
+
+ BN_free(big1);
+ BN_free(big2);
+ BN_free(big32);
+ BN_free(r);
+ BN_free(tmp);
+ BN_free(big2_32);
+ if (ret) {
+ fprintf(stderr, "Bignum operations failed\n");
+ return -ENOMEM;
+ }
+
+ return ret;
+}
+
+static int fdt_add_bignum(void *blob, int noffset, const char *prop_name,
+ BIGNUM *num, int num_bits)
+{
+ int nwords = num_bits / 32;
+ int size;
+ uint32_t *buf, *ptr;
+ BIGNUM *tmp, *big2, *big32, *big2_32;
+ BN_CTX *ctx;
+ int ret;
+
+ tmp = BN_new();
+ big2 = BN_new();
+ big32 = BN_new();
+ big2_32 = BN_new();
+ if (!tmp || !big2 || !big32 || !big2_32) {
+ fprintf(stderr, "Out of memory (bignum)\n");
+ return -ENOMEM;
+ }
+ ctx = BN_CTX_new();
+ if (!tmp) {
+ fprintf(stderr, "Out of memory (bignum context)\n");
+ return -ENOMEM;
+ }
+ BN_set_word(big2, 2L);
+ BN_set_word(big32, 32L);
+ BN_exp(big2_32, big2, big32, ctx); /* B = 2^32 */
+
+ size = nwords * sizeof(uint32_t);
+ buf = malloc(size);
+ if (!buf) {
+ fprintf(stderr, "Out of memory (%d bytes)\n", size);
+ return -ENOMEM;
+ }
+
+ /* Write out modulus as big endian array of integers */
+ for (ptr = buf + nwords - 1; ptr >= buf; ptr--) {
+ BN_mod(tmp, num, big2_32, ctx); /* n = N mod B */
+ *ptr = cpu_to_fdt32(BN_get_word(tmp));
+ BN_rshift(num, num, 32); /* N = N/B */
+ }
+
+ ret = fdt_setprop(blob, noffset, prop_name, buf, size);
+ if (ret) {
+ fprintf(stderr, "Failed to write public key to FIT\n");
+ return -ENOSPC;
+ }
+ free(buf);
+ BN_free(tmp);
+ BN_free(big2);
+ BN_free(big32);
+ BN_free(big2_32);
+
+ return ret;
+}
+
+int rsa_add_verify_data(struct image_sign_info *info, void *keydest)
+{
+ BIGNUM *modulus, *r_squared;
+ uint32_t n0_inv;
+ int parent, node;
+ char name[100];
+ int ret;
+ int bits;
+ RSA *rsa;
+
+ debug("%s: Getting verification data\n", __func__);
+ ret = rsa_get_pub_key(info->keydir, info->keyname, &rsa);
+ if (ret)
+ return ret;
+ ret = rsa_get_params(rsa, &n0_inv, &modulus, &r_squared);
+ if (ret)
+ return ret;
+ bits = BN_num_bits(modulus);
+ parent = fdt_subnode_offset(keydest, 0, FIT_SIG_NODENAME);
+ if (parent == -FDT_ERR_NOTFOUND) {
+ parent = fdt_add_subnode(keydest, 0, FIT_SIG_NODENAME);
+ if (parent < 0) {
+ fprintf(stderr, "Couldn't create signature node: %s\n",
+ fdt_strerror(parent));
+ return -EINVAL;
+ }
+ }
+
+ /* Either create or overwrite the named key node */
+ snprintf(name, sizeof(name), "key-%s", info->keyname);
+ node = fdt_subnode_offset(keydest, parent, name);
+ if (node == -FDT_ERR_NOTFOUND) {
+ node = fdt_add_subnode(keydest, parent, name);
+ if (node < 0) {
+ fprintf(stderr, "Could not create key subnode: %s\n",
+ fdt_strerror(node));
+ return -EINVAL;
+ }
+ } else if (node < 0) {
+ fprintf(stderr, "Cannot select keys parent: %s\n",
+ fdt_strerror(node));
+ return -ENOSPC;
+ }
+
+ ret = fdt_setprop_string(keydest, node, "key-name-hint",
+ info->keyname);
+ ret |= fdt_setprop_u32(keydest, node, "rsa,num-bits", bits);
+ ret |= fdt_setprop_u32(keydest, node, "rsa,n0-inverse", n0_inv);
+ ret |= fdt_add_bignum(keydest, node, "rsa,modulus", modulus, bits);
+ ret |= fdt_add_bignum(keydest, node, "rsa,r-squared", r_squared, bits);
+ ret |= fdt_setprop_string(keydest, node, FIT_ALGO_PROP,
+ info->algo->name);
+ if (info->require_keys) {
+ fdt_setprop_string(keydest, node, "required",
+ info->require_keys);
+ }
+ BN_free(modulus);
+ BN_free(r_squared);
+ if (ret)
+ return -EIO;
+
+ return 0;
+}
diff --git a/lib/rsa/rsa-verify.c b/lib/rsa/rsa-verify.c
new file mode 100644
index 0000000..6a02689
--- /dev/null
+++ b/lib/rsa/rsa-verify.c
@@ -0,0 +1,385 @@
+/*
+ * Copyright (c) 2013, Google Inc.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+
+#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)
+
+/* This is the minimum/maximum key size we support, in bits */
+#define RSA_MIN_KEY_BITS 2048
+#define RSA_MAX_KEY_BITS 2048
+
+/* 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
+ *
+ * @key: Key containing modulus to subtract
+ * @num: Number to subtract modulus from, as little endian word array
+ */
+static void subtract_modulus(const struct rsa_public_key *key, uint32_t num[])
+{
+ int64_t acc = 0;
+ uint i;
+
+ for (i = 0; i < key->len; i++) {
+ acc += (uint64_t)num[i] - key->modulus[i];
+ num[i] = (uint32_t)acc;
+ acc >>= 32;
+ }
+}
+
+/**
+ * greater_equal_modulus() - check if a value is >= modulus
+ *
+ * @key: Key containing modulus to check
+ * @num: Number to check against modulus, as little endian word array
+ * @return 0 if num < modulus, 1 if num >= modulus
+ */
+static int greater_equal_modulus(const struct rsa_public_key *key,
+ uint32_t num[])
+{
+ uint32_t i;
+
+ for (i = key->len - 1; i >= 0; i--) {
+ if (num[i] < key->modulus[i])
+ return 0;
+ if (num[i] > key->modulus[i])
+ return 1;
+ }
+
+ return 1; /* equal */
+}
+
+/**
+ * montgomery_mul_add_step() - Perform montgomery multiply-add step
+ *
+ * Operation: montgomery result[] += a * b[] / n0inv % modulus
+ *
+ * @key: RSA key
+ * @result: Place to put result, as little endian word array
+ * @a: Multiplier
+ * @b: Multiplicand, as little endian word array
+ */
+static void montgomery_mul_add_step(const struct rsa_public_key *key,
+ uint32_t result[], const uint32_t a, const uint32_t b[])
+{
+ uint64_t acc_a, acc_b;
+ uint32_t d0;
+ uint i;
+
+ acc_a = (uint64_t)a * b[0] + result[0];
+ d0 = (uint32_t)acc_a * key->n0inv;
+ acc_b = (uint64_t)d0 * key->modulus[0] + (uint32_t)acc_a;
+ for (i = 1; i < key->len; i++) {
+ acc_a = (acc_a >> 32) + (uint64_t)a * b[i] + result[i];
+ acc_b = (acc_b >> 32) + (uint64_t)d0 * key->modulus[i] +
+ (uint32_t)acc_a;
+ result[i - 1] = (uint32_t)acc_b;
+ }
+
+ acc_a = (acc_a >> 32) + (acc_b >> 32);
+
+ result[i - 1] = (uint32_t)acc_a;
+
+ if (acc_a >> 32)
+ subtract_modulus(key, result);
+}
+
+/**
+ * montgomery_mul() - Perform montgomery mutitply
+ *
+ * Operation: montgomery result[] = a[] * b[] / n0inv % modulus
+ *
+ * @key: RSA key
+ * @result: Place to put result, as little endian word array
+ * @a: Multiplier, as little endian word array
+ * @b: Multiplicand, as little endian word array
+ */
+static void montgomery_mul(const struct rsa_public_key *key,
+ uint32_t result[], uint32_t a[], const uint32_t b[])
+{
+ uint i;
+
+ for (i = 0; i < key->len; ++i)
+ result[i] = 0;
+ for (i = 0; i < key->len; ++i)
+ montgomery_mul_add_step(key, result, a[i], b);
+}
+
+/**
+ * pow_mod() - in-place public exponentiation
+ *
+ * @key: RSA key
+ * @inout: Big-endian word array containing value and result
+ */
+static int pow_mod(const struct rsa_public_key *key, uint32_t *inout)
+{
+ uint32_t *result, *ptr;
+ uint i;
+
+ /* Sanity check for stack size - key->len is in 32-bit words */
+ if (key->len > RSA_MAX_KEY_BITS / 32) {
+ debug("RSA key words %u exceeds maximum %d\n", key->len,
+ RSA_MAX_KEY_BITS / 32);
+ return -EINVAL;
+ }
+
+ uint32_t val[key->len], acc[key->len], tmp[key->len];
+ result = tmp; /* Re-use location. */
+
+ /* Convert from big endian byte array to little endian word array. */
+ for (i = 0, ptr = inout + key->len - 1; i < key->len; i++, ptr--)
+ val[i] = get_unaligned_be32(ptr);
+
+ montgomery_mul(key, acc, val, key->rr); /* axx = a * RR / R mod M */
+ for (i = 0; i < 16; i += 2) {
+ montgomery_mul(key, tmp, acc, acc); /* tmp = acc^2 / R mod M */
+ montgomery_mul(key, acc, tmp, tmp); /* acc = tmp^2 / R mod M */
+ }
+ montgomery_mul(key, result, acc, val); /* result = XX * a / R mod M */
+
+ /* Make sure result < mod; result is at most 1x mod too large. */
+ if (greater_equal_modulus(key, result))
+ subtract_modulus(key, result);
+
+ /* Convert to bigendian byte array */
+ for (i = key->len - 1, ptr = inout; (int)i >= 0; i--, ptr++)
+ put_unaligned_be32(result[i], ptr);
+
+ return 0;
+}
+
+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 uint8_t *padding;
+ int pad_len;
+ int ret;
+
+ if (!key || !sig || !hash)
+ return -EIO;
+
+ if (sig_len != (key->len * sizeof(uint32_t))) {
+ debug("Signature is of incorrect length %d\n", sig_len);
+ return -EINVAL;
+ }
+
+ /* Sanity check for stack size */
+ if (sig_len > RSA_MAX_SIG_BITS / 8) {
+ debug("Signature length %u exceeds maximum %d\n", sig_len,
+ RSA_MAX_SIG_BITS / 8);
+ return -EINVAL;
+ }
+
+ uint32_t buf[sig_len / sizeof(uint32_t)];
+
+ memcpy(buf, sig, sig_len);
+
+ ret = pow_mod(key, buf);
+ if (ret)
+ return ret;
+
+ /* Determine padding to use depending on the signature type. */
+ padding = padding_sha1_rsa2048;
+ pad_len = RSA2048_BYTES - SHA1_SUM_LEN;
+
+ /* Check pkcs1.5 padding bytes. */
+ if (memcmp(buf, padding, pad_len)) {
+ debug("In RSAVerify(): Padding check failed!\n");
+ return -EINVAL;
+ }
+
+ /* Check hash. */
+ if (memcmp((uint8_t *)buf + pad_len, hash, sig_len - pad_len)) {
+ debug("In RSAVerify(): Hash check failed!\n");
+ return -EACCES;
+ }
+
+ return 0;
+}
+
+static void rsa_convert_big_endian(uint32_t *dst, const uint32_t *src, int len)
+{
+ int i;
+
+ for (i = 0; i < len; i++)
+ dst[i] = fdt32_to_cpu(src[len - 1 - i]);
+}
+
+static int rsa_verify_with_keynode(struct image_sign_info *info,
+ const void *hash, uint8_t *sig, uint sig_len, int node)
+{
+ const void *blob = info->fdt_blob;
+ struct rsa_public_key key;
+ const void *modulus, *rr;
+ int ret;
+
+ if (node < 0) {
+ debug("%s: Skipping invalid node", __func__);
+ return -EBADF;
+ }
+ if (!fdt_getprop(blob, node, "rsa,n0-inverse", NULL)) {
+ debug("%s: Missing rsa,n0-inverse", __func__);
+ return -EFAULT;
+ }
+ key.len = fdtdec_get_int(blob, node, "rsa,num-bits", 0);
+ key.n0inv = fdtdec_get_int(blob, node, "rsa,n0-inverse", 0);
+ modulus = fdt_getprop(blob, node, "rsa,modulus", NULL);
+ rr = fdt_getprop(blob, node, "rsa,r-squared", NULL);
+ if (!key.len || !modulus || !rr) {
+ debug("%s: Missing RSA key info", __func__);
+ return -EFAULT;
+ }
+
+ /* Sanity check for stack size */
+ if (key.len > RSA_MAX_KEY_BITS || key.len < RSA_MIN_KEY_BITS) {
+ debug("RSA key bits %u outside allowed range %d..%d\n",
+ key.len, RSA_MIN_KEY_BITS, RSA_MAX_KEY_BITS);
+ return -EFAULT;
+ }
+ key.len /= sizeof(uint32_t) * 8;
+ uint32_t key1[key.len], key2[key.len];
+
+ key.modulus = key1;
+ key.rr = key2;
+ rsa_convert_big_endian(key.modulus, modulus, key.len);
+ rsa_convert_big_endian(key.rr, rr, key.len);
+ if (!key.modulus || !key.rr) {
+ debug("%s: Out of memory", __func__);
+ return -ENOMEM;
+ }
+
+ debug("key length %d\n", key.len);
+ ret = rsa_verify_key(&key, sig, sig_len, hash);
+ if (ret) {
+ printf("%s: RSA failed to verify: %d\n", __func__, ret);
+ return ret;
+ }
+
+ return 0;
+}
+
+int rsa_verify(struct image_sign_info *info,
+ const struct image_region region[], int region_count,
+ uint8_t *sig, uint sig_len)
+{
+ const void *blob = info->fdt_blob;
+ uint8_t hash[SHA1_SUM_LEN];
+ int ndepth, noffset;
+ int sig_node, node;
+ char name[100];
+ sha1_context ctx;
+ int ret, i;
+
+ sig_node = fdt_subnode_offset(blob, 0, FIT_SIG_NODENAME);
+ if (sig_node < 0) {
+ debug("%s: No signature node found\n", __func__);
+ 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);
+
+ /* See if we must use a particular key */
+ if (info->required_keynode != -1) {
+ ret = rsa_verify_with_keynode(info, hash, sig, sig_len,
+ info->required_keynode);
+ if (!ret)
+ return ret;
+ }
+
+ /* Look for a key that matches our hint */
+ snprintf(name, sizeof(name), "key-%s", info->keyname);
+ node = fdt_subnode_offset(blob, sig_node, name);
+ ret = rsa_verify_with_keynode(info, hash, sig, sig_len, node);
+ if (!ret)
+ return ret;
+
+ /* No luck, so try each of the keys in turn */
+ for (ndepth = 0, noffset = fdt_next_node(info->fit, sig_node, &ndepth);
+ (noffset >= 0) && (ndepth > 0);
+ noffset = fdt_next_node(info->fit, noffset, &ndepth)) {
+ if (ndepth == 1 && noffset != node) {
+ ret = rsa_verify_with_keynode(info, hash, sig, sig_len,
+ noffset);
+ if (!ret)
+ break;
+ }
+ }
+
+ return ret;
+}
diff --git a/tools/Makefile b/tools/Makefile
index 38fd934..b589cae 100644
--- a/tools/Makefile
+++ b/tools/Makefile
@@ -125,6 +125,9 @@ LIBFDT_OBJ_FILES-y += fdt_rw.o
LIBFDT_OBJ_FILES-y += fdt_strerror.o
LIBFDT_OBJ_FILES-y += fdt_wip.o
+# RSA objects
+RSA_OBJ_FILES-y += rsa-sign.o
+
# Generated LCD/video logo
LOGO_H = $(OBJTREE)/include/bmp_logo.h
LOGO_DATA_H = $(OBJTREE)/include/bmp_logo_data.h
@@ -159,8 +162,10 @@ endif
HOSTSRCS += $(addprefix $(SRCTREE)/,$(EXT_OBJ_FILES-y:.o=.c))
HOSTSRCS += $(addprefix $(SRCTREE)/tools/,$(OBJ_FILES-y:.o=.c))
HOSTSRCS += $(addprefix $(SRCTREE)/lib/libfdt/,$(LIBFDT_OBJ_FILES-y:.o=.c))
+HOSTSRCS += $(addprefix $(SRCTREE)/lib/rsa/,$(RSA_OBJ_FILES-y:.o=.c))
BINS := $(addprefix $(obj),$(sort $(BIN_FILES-y)))
LIBFDT_OBJS := $(addprefix $(obj),$(LIBFDT_OBJ_FILES-y))
+RSA_OBJS := $(addprefix $(obj),$(RSA_OBJ_FILES-y))
# We cannot check CONFIG_FIT_SIGNATURE here since it is not set on the host
FIT_SIG_OBJ_FILES := image-sig.o
@@ -235,8 +240,9 @@ $(obj)mkimage$(SFX): $(obj)aisimage.o \
$(obj)omapimage.o \
$(obj)sha1.o \
$(obj)ublimage.o \
- $(LIBFDT_OBJS)
- $(HOSTCC) $(HOSTCFLAGS) $(HOSTLDFLAGS) -o $@ $^
+ $(LIBFDT_OBJS) \
+ $(RSA_OBJS)
+ $(HOSTCC) $(HOSTCFLAGS) $(HOSTLDFLAGS) -o $@ $^ $(HOSTLIBS)
$(HOSTSTRIP) $@
$(obj)mk$(BOARD)spl$(SFX): $(obj)mkexynosspl.o
@@ -272,6 +278,9 @@ $(obj)%.o: $(SRCTREE)/lib/%.c
$(obj)%.o: $(SRCTREE)/lib/libfdt/%.c
$(HOSTCC) -g $(HOSTCFLAGS_NOPED) -c -o $@ $<
+$(obj)%.o: $(SRCTREE)/lib/rsa/%.c
+ $(HOSTCC) -g $(HOSTCFLAGS_NOPED) -c -o $@ $<
+
subdirs:
ifeq ($(TOOLSUBDIRS),)
@:
--
1.8.3
More information about the U-Boot
mailing list