blob: b691fc36ac366260d105959484bed447fc490b30 [file] [log] [blame]
/* Copyright (c) 2013 The Chromium OS Authors. All rights reserved.
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*
* Common functions between firmware and kernel verified boot.
* (Firmware portion)
*/
#include "sysincludes.h"
#include "2sysincludes.h"
#include "2common.h"
#include "2sha.h"
#include "vboot_api.h"
#include "vboot_common.h"
#include "utility.h"
const char *kVbootErrors[VBOOT_ERROR_MAX] = {
"Success.",
"Key block invalid.",
"Key block signature failed.",
"Key block hash failed.",
"Public key invalid.",
"Preamble invalid.",
"Preamble signature check failed.",
"Shared data invalid."
};
uint64_t OffsetOf(const void *base, const void *ptr)
{
return (uint64_t)(size_t)ptr - (uint64_t)(size_t)base;
}
/* Helper functions to get data pointed to by a public key or signature. */
uint8_t *GetPublicKeyData(VbPublicKey *key)
{
return (uint8_t *)key + key->key_offset;
}
const uint8_t *GetPublicKeyDataC(const VbPublicKey *key)
{
return (const uint8_t *)key + key->key_offset;
}
uint8_t *GetSignatureData(VbSignature *sig)
{
return (uint8_t *)sig + sig->sig_offset;
}
const uint8_t *GetSignatureDataC(const VbSignature *sig)
{
return (const uint8_t *)sig + sig->sig_offset;
}
/*
* Helper functions to verify the data pointed to by a subfield is inside
* the parent data. Returns 0 if inside, 1 if error.
*/
int VerifyMemberInside(const void *parent, uint64_t parent_size,
const void *member, uint64_t member_size,
uint64_t member_data_offset,
uint64_t member_data_size)
{
uint64_t end = OffsetOf(parent, member);
if (end > parent_size)
return 1;
if (UINT64_MAX - end < member_size)
return 1; /* Detect wraparound in integer math */
if (end + member_size > parent_size)
return 1;
if (UINT64_MAX - end < member_data_offset)
return 1;
end += member_data_offset;
if (end > parent_size)
return 1;
if (UINT64_MAX - end < member_data_size)
return 1;
if (end + member_data_size > parent_size)
return 1;
return 0;
}
int VerifyPublicKeyInside(const void *parent, uint64_t parent_size,
const VbPublicKey *key)
{
return VerifyMemberInside(parent, parent_size,
key, sizeof(VbPublicKey),
key->key_offset, key->key_size);
}
int VerifySignatureInside(const void *parent, uint64_t parent_size,
const VbSignature *sig)
{
return VerifyMemberInside(parent, parent_size,
sig, sizeof(VbSignature),
sig->sig_offset, sig->sig_size);
}
void PublicKeyInit(VbPublicKey *key, uint8_t *key_data, uint64_t key_size)
{
key->key_offset = OffsetOf(key, key_data);
key->key_size = key_size;
key->algorithm = kNumAlgorithms; /* Key not present yet */
key->key_version = 0;
}
int PublicKeyCopy(VbPublicKey *dest, const VbPublicKey *src)
{
if (dest->key_size < src->key_size)
return 1;
dest->key_size = src->key_size;
dest->algorithm = src->algorithm;
dest->key_version = src->key_version;
memcpy(GetPublicKeyData(dest), GetPublicKeyDataC(src), src->key_size);
return 0;
}
RSAPublicKey *PublicKeyToRSA(const VbPublicKey *key)
{
RSAPublicKey *rsa;
uint64_t key_size;
if (kNumAlgorithms <= key->algorithm) {
VBDEBUG(("Invalid algorithm.\n"));
return NULL;
}
if (!RSAProcessedKeySize(key->algorithm, &key_size) ||
key_size != key->key_size) {
VBDEBUG(("Wrong key size for algorithm\n"));
return NULL;
}
rsa = RSAPublicKeyFromBuf(GetPublicKeyDataC(key), key->key_size);
if (!rsa)
return NULL;
rsa->algorithm = (unsigned int)key->algorithm;
return rsa;
}
int VerifyData(const uint8_t *data, uint64_t size, const VbSignature *sig,
const RSAPublicKey *key)
{
VBDEBUG((" - sig_size=%d, expecting %d for algorithm %d\n",
(unsigned)sig->sig_size, siglen_map[key->algorithm],
key->algorithm));
if (sig->sig_size != siglen_map[key->algorithm]) {
VBDEBUG(("Wrong data signature size for algorithm, "
"sig_size=%d, expected %d for algorithm %d.\n",
(int)sig->sig_size, siglen_map[key->algorithm],
key->algorithm));
return 1;
}
if (sig->data_size > size) {
VBDEBUG(("Data buffer smaller than length of signed data.\n"));
return 1;
}
if (!RSAVerifyBinary_f(NULL, key, data, sig->data_size,
GetSignatureDataC(sig), key->algorithm))
return 1;
return 0;
}
int VerifyDigest(const uint8_t *digest, const VbSignature *sig,
const RSAPublicKey *key)
{
if (sig->sig_size != siglen_map[key->algorithm]) {
VBDEBUG(("Wrong digest signature size for algorithm.\n"));
return 1;
}
if (!RSAVerifyBinaryWithDigest_f(NULL, key, digest,
GetSignatureDataC(sig),
key->algorithm))
return 1;
return 0;
}
int KeyBlockVerify(const VbKeyBlockHeader *block, uint64_t size,
const VbPublicKey *key, int hash_only)
{
const VbSignature *sig;
/* Sanity checks before attempting signature of data */
if(size < sizeof(VbKeyBlockHeader)) {
VBDEBUG(("Not enough space for key block header.\n"));
return VBOOT_KEY_BLOCK_INVALID;
}
if (SafeMemcmp(block->magic, KEY_BLOCK_MAGIC, KEY_BLOCK_MAGIC_SIZE)) {
VBDEBUG(("Not a valid verified boot key block.\n"));
return VBOOT_KEY_BLOCK_INVALID;
}
if (block->header_version_major != KEY_BLOCK_HEADER_VERSION_MAJOR) {
VBDEBUG(("Incompatible key block header version.\n"));
return VBOOT_KEY_BLOCK_INVALID;
}
if (size < block->key_block_size) {
VBDEBUG(("Not enough data for key block.\n"));
return VBOOT_KEY_BLOCK_INVALID;
}
if (!hash_only && !key) {
VBDEBUG(("Missing required public key.\n"));
return VBOOT_PUBLIC_KEY_INVALID;
}
/*
* Check signature or hash, depending on the hash_only parameter. Note
* that we don't require a key even if the keyblock has a signature,
* because the caller may not care if the keyblock itself is signed
* (for example, booting a Google-signed kernel in developer mode).
*/
if (hash_only) {
/* Check hash */
uint8_t header_checksum[VB2_SHA512_DIGEST_SIZE];
int rv;
sig = &block->key_block_checksum;
if (VerifySignatureInside(block, block->key_block_size, sig)) {
VBDEBUG(("Key block hash off end of block\n"));
return VBOOT_KEY_BLOCK_INVALID;
}
if (sig->sig_size != VB2_SHA512_DIGEST_SIZE) {
VBDEBUG(("Wrong hash size for key block.\n"));
return VBOOT_KEY_BLOCK_INVALID;
}
/* Make sure advertised signature data sizes are sane. */
if (block->key_block_size < sig->data_size) {
VBDEBUG(("Signature calculated past end of block\n"));
return VBOOT_KEY_BLOCK_INVALID;
}
VBDEBUG(("Checking key block hash only...\n"));
rv = vb2_digest_buffer((const uint8_t *)block,
sig->data_size,
VB2_HASH_SHA512,
header_checksum,
sizeof(header_checksum));
if (!rv)
rv = SafeMemcmp(header_checksum, GetSignatureDataC(sig),
sizeof(header_checksum));
if (rv) {
VBDEBUG(("Invalid key block hash.\n"));
return VBOOT_KEY_BLOCK_HASH;
}
} else {
/* Check signature */
RSAPublicKey *rsa;
int rv;
sig = &block->key_block_signature;
if (VerifySignatureInside(block, block->key_block_size, sig)) {
VBDEBUG(("Key block signature off end of block\n"));
return VBOOT_KEY_BLOCK_INVALID;
}
rsa = PublicKeyToRSA(key);
if (!rsa) {
VBDEBUG(("Invalid public key\n"));
return VBOOT_PUBLIC_KEY_INVALID;
}
/* Make sure advertised signature data sizes are sane. */
if (block->key_block_size < sig->data_size) {
VBDEBUG(("Signature calculated past end of block\n"));
RSAPublicKeyFree(rsa);
return VBOOT_KEY_BLOCK_INVALID;
}
VBDEBUG(("Checking key block signature...\n"));
rv = VerifyData((const uint8_t *)block, size, sig, rsa);
RSAPublicKeyFree(rsa);
if (rv) {
VBDEBUG(("Invalid key block signature.\n"));
return VBOOT_KEY_BLOCK_SIGNATURE;
}
}
/* Verify we signed enough data */
if (sig->data_size < sizeof(VbKeyBlockHeader)) {
VBDEBUG(("Didn't sign enough data\n"));
return VBOOT_KEY_BLOCK_INVALID;
}
/* Verify data key is inside the block and inside signed data */
if (VerifyPublicKeyInside(block, block->key_block_size,
&block->data_key)) {
VBDEBUG(("Data key off end of key block\n"));
return VBOOT_KEY_BLOCK_INVALID;
}
if (VerifyPublicKeyInside(block, sig->data_size, &block->data_key)) {
VBDEBUG(("Data key off end of signed data\n"));
return VBOOT_KEY_BLOCK_INVALID;
}
/* Success */
return VBOOT_SUCCESS;
}
int VerifyKernelPreamble(const VbKernelPreambleHeader *preamble,
uint64_t size, const RSAPublicKey *key)
{
const VbSignature *sig = &preamble->preamble_signature;
/* Sanity checks before attempting signature of data */
if(size < sizeof(VbKernelPreambleHeader)) {
VBDEBUG(("Not enough data for preamble header.\n"));
return VBOOT_PREAMBLE_INVALID;
}
if (preamble->header_version_major !=
KERNEL_PREAMBLE_HEADER_VERSION_MAJOR) {
VBDEBUG(("Incompatible kernel preamble header version.\n"));
return VBOOT_PREAMBLE_INVALID;
}
if (size < preamble->preamble_size) {
VBDEBUG(("Not enough data for preamble.\n"));
return VBOOT_PREAMBLE_INVALID;
}
/* Check signature */
if (VerifySignatureInside(preamble, preamble->preamble_size, sig)) {
VBDEBUG(("Preamble signature off end of preamble\n"));
return VBOOT_PREAMBLE_INVALID;
}
if (VerifyData((const uint8_t *)preamble, size, sig, key)) {
VBDEBUG(("Preamble signature validation failed\n"));
return VBOOT_PREAMBLE_SIGNATURE;
}
/* Verify we signed enough data */
if (sig->data_size < sizeof(VbKernelPreambleHeader)) {
VBDEBUG(("Didn't sign enough data\n"));
return VBOOT_PREAMBLE_INVALID;
}
/* Verify body signature is inside the signed data */
if (VerifySignatureInside(preamble, sig->data_size,
&preamble->body_signature)) {
VBDEBUG(("Kernel body signature off end of preamble\n"));
return VBOOT_PREAMBLE_INVALID;
}
/*
* If the preamble header version is at least 2.1, verify we have space
* for the added fields from >2.1.
*/
if (preamble->header_version_minor >= 1) {
if((preamble->header_version_minor == 1) &&
(size < EXPECTED_VBKERNELPREAMBLEHEADER2_1_SIZE)) {
VBDEBUG(("Not enough data for preamble header 2.1.\n"));
return VBOOT_PREAMBLE_INVALID;
}
if((preamble->header_version_minor == 2) &&
(size < EXPECTED_VBKERNELPREAMBLEHEADER2_2_SIZE)) {
VBDEBUG(("Not enough data for preamble header 2.2.\n"));
return VBOOT_PREAMBLE_INVALID;
}
}
/* Success */
return VBOOT_SUCCESS;
}
int VbGetKernelVmlinuzHeader(const VbKernelPreambleHeader *preamble,
uint64_t *vmlinuz_header_address,
uint64_t *vmlinuz_header_size)
{
*vmlinuz_header_address = 0;
*vmlinuz_header_size = 0;
if (preamble->header_version_minor > 0) {
/*
* Set header and size only if the preamble header version is >
* 2.1 as they don't exist in version 2.0 (Note that we don't
* need to check header_version_major; if that's not 2 then
* VerifyKernelPreamble() would have already failed.
*/
*vmlinuz_header_address = preamble->vmlinuz_header_address;
*vmlinuz_header_size = preamble->vmlinuz_header_size;
}
return VBOOT_SUCCESS;
}
int VbKernelHasFlags(const VbKernelPreambleHeader *preamble)
{
if (preamble->header_version_minor > 1)
return VBOOT_SUCCESS;
return VBOOT_KERNEL_PREAMBLE_NO_FLAGS;
}
int VerifyVmlinuzInsideKBlob(uint64_t kblob, uint64_t kblob_size,
uint64_t header, uint64_t header_size)
{
uint64_t end = header-kblob;
if (end > kblob_size)
return VBOOT_PREAMBLE_INVALID;
if (UINT64_MAX - end < header_size)
return VBOOT_PREAMBLE_INVALID;
if (end + header_size > kblob_size)
return VBOOT_PREAMBLE_INVALID;
return VBOOT_SUCCESS;
}
uint64_t VbSharedDataReserve(VbSharedDataHeader *header, uint64_t size)
{
if (!header || size > header->data_size - header->data_used) {
VBDEBUG(("VbSharedData buffer out of space.\n"));
return 0; /* Not initialized, or not enough space left. */
}
uint64_t offs = header->data_used;
VBDEBUG(("VbSharedDataReserve %d bytes at %d\n", (int)size, (int)offs));
header->data_used += size;
return offs;
}
int VbSharedDataSetKernelKey(VbSharedDataHeader *header, const VbPublicKey *src)
{
VbPublicKey *kdest;
if (!header)
return VBOOT_SHARED_DATA_INVALID;
if (!src)
return VBOOT_PUBLIC_KEY_INVALID;
kdest = &header->kernel_subkey;
VBDEBUG(("Saving kernel subkey to shared data: size %d, algo %d\n",
siglen_map[src->algorithm], (int)src->algorithm));
/* Attempt to allocate space for key, if it hasn't been allocated yet */
if (!header->kernel_subkey_data_offset) {
header->kernel_subkey_data_offset =
VbSharedDataReserve(header, src->key_size);
if (!header->kernel_subkey_data_offset)
return VBOOT_SHARED_DATA_INVALID;
header->kernel_subkey_data_size = src->key_size;
}
/* Copy the kernel sign key blob into the destination buffer */
PublicKeyInit(kdest,
(uint8_t *)header + header->kernel_subkey_data_offset,
header->kernel_subkey_data_size);
return PublicKeyCopy(kdest, src);
}