--- /dev/null
+/*
+ * Copyright (c) 2013, Google Inc.
+ *
+ * SPDX-License-Identifier: GPL-2.0+
+ */
+
+#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;
+}
projects / karo-tx-uboot.git / blobdiff