Public exponentiation which is required in rsa verify functionality is
tightly integrated with verification code in rsa_verify.c. The patch
splits the file into twp separating the modular exponentiation.
1. rsa-verify.c
- The file parses device tree keys node to fill a keyprop structure.
The keyprop structure can then be converted to implementation specific
format.
(struct rsa_pub_key for sw implementation)
- The parsed device tree node is then passed to a generic rsa_mod_exp
function.
2. rsa-mod-exp.c
Move the software specific functions related to modular exponentiation
from rsa-verify.c to this file.
Signed-off-by: Ruchika Gupta <ruchika.gupta(a)freescale.com>
CC: Simon Glass <sjg(a)chromium.org>
---
Changes in v4:
Modified rsa_mod_exp_sw function to add pointer to output length
Changes in v3:
Kconfig moved to separate patch. This patch just splits the file now
Changes in v2:
Addressed few of Simon Glass's comments:
- Kconfig option added for RSA
- Comments added for new keyprop struct
include/u-boot/rsa-mod-exp.h | 49 +++++++
lib/rsa/Makefile | 2 +-
lib/rsa/rsa-mod-exp.c | 309 ++++++++++++++++++++++++++++++++++++++
lib/rsa/rsa-verify.c | 343 +++++++++----------------------------------
tools/Makefile | 3 +-
5 files changed, 429 insertions(+), 277 deletions(-)
create mode 100644 include/u-boot/rsa-mod-exp.h
create mode 100644 lib/rsa/rsa-mod-exp.c
diff --git a/include/u-boot/rsa-mod-exp.h b/include/u-boot/rsa-mod-exp.h
new file mode 100644
index 0000000..7b74f3c
--- /dev/null
+++ b/include/u-boot/rsa-mod-exp.h
@@ -0,0 +1,49 @@
+/*
+ * Copyright (c) 2014, Ruchika Gupta.
+ *
+ * SPDX-License-Identifier: GPL-2.0+
+*/
+
+#ifndef _RSA_MOD_EXP_H
+#define _RSA_MOD_EXP_H
+
+#include <errno.h>
+#include <image.h>
+
+/**
+ * struct key_prop - holder for a public key properties
+ *
+ * The struct has pointers to modulus (Typically called N),
+ * The inverse, R^2, exponent. These can be typecasted and
+ * used as byte arrays or converted to the required format
+ * as per requirement of RSA implementation.
+ */
+struct key_prop {
+ const void *rr; /* R^2 can be treated as byte array */
+ const void *modulus; /* modulus as byte array */
+ const void *public_exponent; /* public exponent as byte array */
+ uint32_t n0inv; /* -1 / modulus[0] mod 2^32 */
+ int num_bits; /* Key length in bits */
+ uint32_t exp_len; /* Exponent length in number of uint8_t */
+};
+
+/**
+ * rsa_mod_exp_sw() - Perform RSA Modular Exponentiation in sw
+ *
+ * Operation: result[] = sig ^ exponent % modulus
+ *
+ * @sig: RSA PKCS1.5 signature
+ * @sig_len: Length of signature in number of bytes
+ * @node: Node with RSA key elements like modulus, exponent, R^2, n0inv
+ * @outp: Set to an allocated buffer holding the output hash
+ * @out_len: Set to length of hash(outp) calculated after exponentiation
+ *
+ * This computes exponentiation over the signature. Resulting hash value is
+ * placed in an allocated buffer, the pointer is returned as *outp. The
+ * length of calulated hash is returned via the out_len pointer argument. The
+ * caller should free *outp
+ */
+int rsa_mod_exp_sw(const uint8_t *sig, uint32_t sig_len,
+ struct key_prop *node, uint8_t **outp, uint32_t *out_len);
+
+#endif
diff --git a/lib/rsa/Makefile b/lib/rsa/Makefile
index a5a96cb6..cc25b3c 100644
--- a/lib/rsa/Makefile
+++ b/lib/rsa/Makefile
@@ -7,4 +7,4 @@
# SPDX-License-Identifier: GPL-2.0+
#
-obj-$(CONFIG_FIT_SIGNATURE) += rsa-verify.o rsa-checksum.o
+obj-$(CONFIG_FIT_SIGNATURE) += rsa-verify.o rsa-checksum.o rsa-mod-exp.o
diff --git a/lib/rsa/rsa-mod-exp.c b/lib/rsa/rsa-mod-exp.c
new file mode 100644
index 0000000..af01b74
--- /dev/null
+++ b/lib/rsa/rsa-mod-exp.c
@@ -0,0 +1,309 @@
+/*
+ * Copyright (c) 2013, Google Inc.
+ *
+ * SPDX-License-Identifier: GPL-2.0+
+ */
+
+#ifndef USE_HOSTCC
+#include <common.h>
+#include <fdtdec.h>
+#include <asm/types.h>
+#include <asm/byteorder.h>
+#include <asm/errno.h>
+#include <asm/types.h>
+#include <asm/unaligned.h>
+#else
+#include "fdt_host.h"
+#include "mkimage.h"
+#include <fdt_support.h>
+#endif
+#include <malloc.h>
+#include <u-boot/rsa.h>
+#include <u-boot/rsa-mod-exp.h>
+
+#define UINT64_MULT32(v, multby) (((uint64_t)(v)) * ((uint32_t)(multby)))
+
+#define get_unaligned_be32(a) fdt32_to_cpu(*(uint32_t *)a)
+#define put_unaligned_be32(a, b) (*(uint32_t *)(b) = cpu_to_fdt32(a))
+
+/* Default public exponent for backward compatibility */
+#define RSA_DEFAULT_PUBEXP 65537
+
+/**
+ * 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[])
+{
+ int i;
+
+ for (i = (int)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);
+}
+
+/**
+ * num_pub_exponent_bits() - Number of bits in the public exponent
+ *
+ * @key: RSA key
+ * @num_bits: Storage for the number of public exponent bits
+ */
+static int num_public_exponent_bits(const struct rsa_public_key *key,
+ int *num_bits)
+{
+ uint64_t exponent;
+ int exponent_bits;
+ const uint max_bits = (sizeof(exponent) * 8);
+
+ exponent = key->exponent;
+ exponent_bits = 0;
+
+ if (!exponent) {
+ *num_bits = exponent_bits;
+ return 0;
+ }
+
+ for (exponent_bits = 1; exponent_bits < max_bits + 1; ++exponent_bits)
+ if (!(exponent >>= 1)) {
+ *num_bits = exponent_bits;
+ return 0;
+ }
+
+ return -EINVAL;
+}
+
+/**
+ * is_public_exponent_bit_set() - Check if a bit in the public exponent is set
+ *
+ * @key: RSA key
+ * @pos: The bit position to check
+ */
+static int is_public_exponent_bit_set(const struct rsa_public_key *key,
+ int pos)
+{
+ return key->exponent & (1ULL << pos);
+}
+
+/**
+ * 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;
+ int j, k;
+
+ /* 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];
+ uint32_t a_scaled[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);
+
+ if (0 != num_public_exponent_bits(key, &k))
+ return -EINVAL;
+
+ if (k < 2) {
+ debug("Public exponent is too short (%d bits, minimum 2)\n",
+ k);
+ return -EINVAL;
+ }
+
+ if (!is_public_exponent_bit_set(key, 0)) {
+ debug("LSB of RSA public exponent must be set.\n");
+ return -EINVAL;
+ }
+
+ /* the bit at e[k-1] is 1 by definition, so start with: C := M */
+ montgomery_mul(key, acc, val, key->rr); /* acc = a * RR / R mod n */
+ /* retain scaled version for intermediate use */
+ memcpy(a_scaled, acc, key->len * sizeof(a_scaled[0]));
+
+ for (j = k - 2; j > 0; --j) {
+ montgomery_mul(key, tmp, acc, acc); /* tmp = acc^2 / R mod n */
+
+ if (is_public_exponent_bit_set(key, j)) {
+ /* acc = tmp * val / R mod n */
+ montgomery_mul(key, acc, tmp, a_scaled);
+ } else {
+ /* e[j] == 0, copy tmp back to acc for next operation */
+ memcpy(acc, tmp, key->len * sizeof(acc[0]));
+ }
+ }
+
+ /* the bit at e[0] is always 1 */
+ montgomery_mul(key, tmp, acc, acc); /* tmp = acc^2 / R mod n */
+ montgomery_mul(key, acc, tmp, val); /* acc = tmp * a / R mod M */
+ memcpy(result, acc, key->len * sizeof(result[0]));
+
+ /* 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 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]);
+}
+
+int rsa_mod_exp_sw(const uint8_t *sig, uint32_t sig_len,
+ struct key_prop *prop, uint8_t **out, uint32_t *len)
+{
+ struct rsa_public_key key;
+ int ret;
+
+ if (!prop) {
+ debug("%s: Skipping invalid prop", __func__);
+ return -EBADF;
+ }
+ if (!prop->n0inv) {
+ debug("%s: Missing rsa,n0-inverse", __func__);
+ return -EFAULT;
+ }
+ key.n0inv = prop->n0inv;
+ key.len = prop->num_bits;
+
+ if (!prop->public_exponent)
+ key.exponent = RSA_DEFAULT_PUBEXP;
+ else
+ key.exponent =
+ fdt64_to_cpu(*((uint64_t *)(prop->public_exponent)));
+
+ if (!key.len || !prop->modulus || !prop->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, (uint32_t *)prop->modulus, key.len);
+ rsa_convert_big_endian(key.rr, (uint32_t *)prop->rr, key.len);
+ if (!key.modulus || !key.rr) {
+ debug("%s: Out of memory", __func__);
+ return -ENOMEM;
+ }
+
+ uint32_t *buf = malloc(sig_len);
+
+ memcpy(buf, sig, sig_len);
+
+ ret = pow_mod(&key, buf);
+ if (ret)
+ return ret;
+
+ *out = (uint8_t *)buf;
+ *len = sig_len;
+
+ return 0;
+}
diff --git a/lib/rsa/rsa-verify.c b/lib/rsa/rsa-verify.c
index 4ef19b6..1d2e707 100644
--- a/lib/rsa/rsa-verify.c
+++ b/lib/rsa/rsa-verify.c
@@ -17,230 +17,27 @@
#include "mkimage.h"
#include <fdt_support.h>
#endif
+#include <malloc.h>
+#include <u-boot/rsa-mod-exp.h>
#include <u-boot/rsa.h>
-#include <u-boot/sha1.h>
-#include <u-boot/sha256.h>
-
-#define UINT64_MULT32(v, multby) (((uint64_t)(v)) * ((uint32_t)(multby)))
-
-#define get_unaligned_be32(a) fdt32_to_cpu(*(uint32_t *)a)
-#define put_unaligned_be32(a, b) (*(uint32_t *)(b) = cpu_to_fdt32(a))
/* Default public exponent for backward compatibility */
#define RSA_DEFAULT_PUBEXP 65537
/**
- * subtract_modulus() - subtract modulus from the given value
+ * rsa_verify_key() - Verify a signature against some data using RSA Key
*
- * @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
+ * Verify a RSA PKCS1.5 signature against an expected hash using
+ * the RSA Key properties in prop structure.
*
- * @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
+ * @prop: Specifies key
+ * @sig: Signature
+ * @sig_len: Number of bytes in signature
+ * @hash: Pointer to the expected hash
+ * @algo: Checksum algo structure having information on RSA padding etc.
+ * @return 0 if verified, -ve on error
*/
-static int greater_equal_modulus(const struct rsa_public_key *key,
- uint32_t num[])
-{
- int i;
-
- for (i = (int)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);
-}
-
-/**
- * num_pub_exponent_bits() - Number of bits in the public exponent
- *
- * @key: RSA key
- * @num_bits: Storage for the number of public exponent bits
- */
-static int num_public_exponent_bits(const struct rsa_public_key *key,
- int *num_bits)
-{
- uint64_t exponent;
- int exponent_bits;
- const uint max_bits = (sizeof(exponent) * 8);
-
- exponent = key->exponent;
- exponent_bits = 0;
-
- if (!exponent) {
- *num_bits = exponent_bits;
- return 0;
- }
-
- for (exponent_bits = 1; exponent_bits < max_bits + 1; ++exponent_bits)
- if (!(exponent >>= 1)) {
- *num_bits = exponent_bits;
- return 0;
- }
-
- return -EINVAL;
-}
-
-/**
- * is_public_exponent_bit_set() - Check if a bit in the public exponent is set
- *
- * @key: RSA key
- * @pos: The bit position to check
- */
-static int is_public_exponent_bit_set(const struct rsa_public_key *key,
- int pos)
-{
- return key->exponent & (1ULL << pos);
-}
-
-/**
- * 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;
- int j, k;
-
- /* 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];
- uint32_t a_scaled[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);
-
- if (0 != num_public_exponent_bits(key, &k))
- return -EINVAL;
-
- if (k < 2) {
- debug("Public exponent is too short (%d bits, minimum 2)\n",
- k);
- return -EINVAL;
- }
-
- if (!is_public_exponent_bit_set(key, 0)) {
- debug("LSB of RSA public exponent must be set.\n");
- return -EINVAL;
- }
-
- /* the bit at e[k-1] is 1 by definition, so start with: C := M */
- montgomery_mul(key, acc, val, key->rr); /* acc = a * RR / R mod n */
- /* retain scaled version for intermediate use */
- memcpy(a_scaled, acc, key->len * sizeof(a_scaled[0]));
-
- for (j = k - 2; j > 0; --j) {
- montgomery_mul(key, tmp, acc, acc); /* tmp = acc^2 / R mod n */
-
- if (is_public_exponent_bit_set(key, j)) {
- /* acc = tmp * val / R mod n */
- montgomery_mul(key, acc, tmp, a_scaled);
- } else {
- /* e[j] == 0, copy tmp back to acc for next operation */
- memcpy(acc, tmp, key->len * sizeof(acc[0]));
- }
- }
-
- /* the bit at e[0] is always 1 */
- montgomery_mul(key, tmp, acc, acc); /* tmp = acc^2 / R mod n */
- montgomery_mul(key, acc, tmp, val); /* acc = tmp * a / R mod M */
- memcpy(result, acc, key->len * sizeof(result[0]));
-
- /* 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,
+static int rsa_verify_key(struct key_prop *prop, const uint8_t *sig,
const uint32_t sig_len, const uint8_t *hash,
struct checksum_algo *algo)
{
@@ -248,10 +45,10 @@ static int rsa_verify_key(const struct rsa_public_key *key, const uint8_t *sig,
int pad_len;
int ret;
- if (!key || !sig || !hash || !algo)
+ if (!prop || !sig || !hash || !algo)
return -EIO;
- if (sig_len != (key->len * sizeof(uint32_t))) {
+ if (sig_len != (prop->num_bits / 8)) {
debug("Signature is of incorrect length %d\n", sig_len);
return -EINVAL;
}
@@ -265,13 +62,20 @@ static int rsa_verify_key(const struct rsa_public_key *key, const uint8_t *sig,
return -EINVAL;
}
- uint32_t buf[sig_len / sizeof(uint32_t)];
+ uint8_t *buf;
+ uint32_t buf_len;
- memcpy(buf, sig, sig_len);
-
- ret = pow_mod(key, buf);
- if (ret)
+ ret = rsa_mod_exp_sw(sig, sig_len, prop, &buf, &buf_len);
+ if (ret) {
+ debug("Error in Modular exponentation\n");
return ret;
+ }
+
+ if (buf_len != sig_len) {
+ debug("In RSAVerify(): hash length not same as sig len\n");
+ free(buf);
+ return -EINVAL;
+ }
padding = algo->rsa_padding;
pad_len = algo->pad_len - algo->checksum_len;
@@ -279,84 +83,73 @@ static int rsa_verify_key(const struct rsa_public_key *key, const uint8_t *sig,
/* Check pkcs1.5 padding bytes. */
if (memcmp(buf, padding, pad_len)) {
debug("In RSAVerify(): Padding check failed!\n");
+ free(buf);
return -EINVAL;
}
/* Check hash. */
- if (memcmp((uint8_t *)buf + pad_len, hash, sig_len - pad_len)) {
+ if (memcmp(buf + pad_len, hash, sig_len - pad_len)) {
debug("In RSAVerify(): Hash check failed!\n");
+ free(buf);
return -EACCES;
}
- return 0;
-}
-
-static void rsa_convert_big_endian(uint32_t *dst, const uint32_t *src, int len)
-{
- int i;
+ free(buf);
- for (i = 0; i < len; i++)
- dst[i] = fdt32_to_cpu(src[len - 1 - i]);
+ return 0;
}
+/**
+ * rsa_verify_with_keynode() - Verify a signature against some data using
+ * information in node with prperties of RSA Key like modulus, exponent etc.
+ *
+ * Parse sign-node and fill a key_prop structure with properties of the
+ * key. Verify a RSA PKCS1.5 signature against an expected hash using
+ * the properties parsed
+ *
+ * @info: Specifies key and FIT information
+ * @hash: Pointer to the expected hash
+ * @sig: Signature
+ * @sig_len: Number of bytes in signature
+ * @node: Node having the RSA Key properties
+ * @return 0 if verified, -ve on error
+ */
static int rsa_verify_with_keynode(struct image_sign_info *info,
- const void *hash, uint8_t *sig, uint sig_len, int node)
+ 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;
- const uint64_t *public_exponent;
+ struct key_prop prop;
int length;
- int ret;
+ int ret = 0;
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);
- public_exponent = fdt_getprop(blob, node, "rsa,exponent", &length);
- if (!public_exponent || length < sizeof(*public_exponent))
- key.exponent = RSA_DEFAULT_PUBEXP;
- else
- key.exponent = fdt64_to_cpu(*public_exponent);
- 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);
+ prop.num_bits = fdtdec_get_int(blob, node, "rsa,num-bits", 0);
+
+ prop.n0inv = fdtdec_get_int(blob, node, "rsa,n0-inverse", 0);
+
+ prop.public_exponent = fdt_getprop(blob, node, "rsa,exponent", &length);
+ if (!prop.public_exponent || length < sizeof(uint64_t))
+ prop.public_exponent = NULL;
+
+ prop.exp_len = sizeof(uint64_t);
+
+ prop.modulus = fdt_getprop(blob, node, "rsa,modulus", NULL);
+
+ prop.rr = fdt_getprop(blob, node, "rsa,r-squared", NULL);
+
+ if (!prop.num_bits || !prop.modulus) {
+ debug("%s: Missing RSA key info", __func__);
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, info->algo->checksum);
- if (ret) {
- printf("%s: RSA failed to verify: %d\n", __func__, ret);
- return ret;
- }
+ ret = rsa_verify_key(&prop, sig, sig_len, hash, info->algo->checksum);
- return 0;
+ return ret;
}
int rsa_verify(struct image_sign_info *info,
diff --git a/tools/Makefile b/tools/Makefile
index a4216a1..0b981da 100644
--- a/tools/Makefile
+++ b/tools/Makefile
@@ -60,7 +60,8 @@ FIT_SIG_OBJS-$(CONFIG_FIT_SIGNATURE) := common/image-sig.o
LIBFDT_OBJS := $(addprefix lib/libfdt/, \
fdt.o fdt_ro.o fdt_rw.o fdt_strerror.o fdt_wip.o)
RSA_OBJS-$(CONFIG_FIT_SIGNATURE) := $(addprefix lib/rsa/, \
- rsa-sign.o rsa-verify.o rsa-checksum.o)
+ rsa-sign.o rsa-verify.o rsa-checksum.o \
+ rsa-mod-exp.o)
# common objs for dumpimage and mkimage
dumpimage-mkimage-objs := aisimage.o \
--
1.8.1.4
