* Copyright (C) 2021, Huawei Technologies Co., Ltd
*/
#include <config.h>
#include <crypto/crypto.h>
#include <kernel/linker.h>
#include <kernel/pseudo_ta.h>
#include <kernel/ts_store.h>
#include <kernel/user_mode_ctx.h>
#include <mm/file.h>
#include <pta_attestation.h>
#include <stdlib.h>
#include <string.h>
#include <tee/entry_std.h>
#include <tee/tee_fs.h>
#include <tee/tee_pobj.h>
#include <tee/uuid.h>
#include <utee_defines.h>
#define PTA_NAME "attestation.pta"
#define MAX_KEY_SIZE 4096
static TEE_UUID pta_uuid = PTA_ATTESTATION_UUID;
static struct rsa_keypair *key;
static const uint8_t key_file_name[] = "key";
static TEE_Result allocate_key(void)
{
assert(!key);
key = calloc(1, sizeof(*key));
if (!key)
return TEE_ERROR_OUT_OF_MEMORY;
COMPILE_TIME_ASSERT(CFG_ATTESTATION_PTA_KEY_SIZE <= MAX_KEY_SIZE);
return crypto_acipher_alloc_rsa_keypair(key, MAX_KEY_SIZE);
}
static void free_key(void)
{
crypto_acipher_free_rsa_keypair(key);
free(key);
key = NULL;
}
static TEE_Result generate_key(void)
{
uint32_t e = TEE_U32_TO_BIG_ENDIAN(65537);
TEE_Result res = TEE_ERROR_GENERIC;
res = allocate_key();
if (res)
return res;
crypto_bignum_bin2bn((uint8_t *)&e, sizeof(e), key->e);
* For security reasons, the RSA modulus size has to be at least the
* size of the data to be signed.
*/
DMSG("Generating %u bit RSA key pair", CFG_ATTESTATION_PTA_KEY_SIZE);
COMPILE_TIME_ASSERT(CFG_ATTESTATION_PTA_KEY_SIZE >=
TEE_SHA256_HASH_SIZE);
res = crypto_acipher_gen_rsa_key(key, CFG_ATTESTATION_PTA_KEY_SIZE);
if (res)
free_key();
return res;
}
* Return values:
* > 0 : Number of bytes written to buf
* 0 : @sz too large (> UINT16_MAX) or @buf_sz too small
*/
static size_t serialize_bignum(uint8_t *buf, size_t buf_sz, struct bignum *bn)
{
uint8_t *p = buf;
size_t sz = crypto_bignum_num_bytes(bn);
uint16_t val = TEE_U16_TO_BIG_ENDIAN(sz);
size_t total_sz = sizeof(val) + sz;
if (sz > UINT16_MAX || total_sz > buf_sz)
return 0;
memcpy(p, &val, sizeof(val));
p += sizeof(val);
crypto_bignum_bn2bin(bn, p);
return total_sz;
}
static size_t bufsize(size_t e_sz, size_t d_sz, size_t n_sz)
{
* Serialized key pair is 3 bignums (e, p and n) plus their sizes
* encoded as uint16_t.
*/
return e_sz + d_sz + n_sz + 3 * sizeof(uint16_t);
}
static TEE_Result serialize_key(uint8_t *buf, size_t size)
{
TEE_Result res = TEE_ERROR_GENERIC;
uint8_t *p = buf;
size_t needed_sz = 0;
size_t e_sz = 0;
size_t d_sz = 0;
size_t n_sz = 0;
size_t sz = 0;
assert(key);
e_sz = crypto_bignum_num_bytes(key->e);
d_sz = crypto_bignum_num_bytes(key->d);
n_sz = crypto_bignum_num_bytes(key->n);
if (e_sz > UINT16_MAX || d_sz > UINT16_MAX || n_sz > UINT16_MAX)
goto err;
needed_sz = bufsize(e_sz, d_sz, n_sz);
if (size < needed_sz)
goto err;
sz = serialize_bignum(p, needed_sz, key->e);
if (!sz)
goto err;
p += sz;
needed_sz -= sz;
sz = serialize_bignum(p, needed_sz, key->d);
if (!sz)
goto err;
p += sz;
needed_sz -= sz;
sz = serialize_bignum(p, needed_sz, key->n);
if (!sz)
goto err;
needed_sz -= sz;
assert(!needed_sz);
return TEE_SUCCESS;
err:
return res;
}
static size_t deserialize_bignum(uint8_t *buf, size_t max_sz, struct bignum *bn)
{
TEE_Result res = TEE_ERROR_GENERIC;
uint8_t *p = buf;
uint16_t val = 0;
size_t sz = 0;
if (max_sz < sizeof(val))
return 0;
memcpy(&val, p, sizeof(val));
sz = TEE_U16_FROM_BIG_ENDIAN(val);
p += sizeof(val);
max_sz -= sizeof(val);
if (max_sz < sz)
return 0;
res = crypto_bignum_bin2bn(p, sz, bn);
if (res)
return 0;
return sizeof(val) + sz;
}
static TEE_Result deserialize_key(uint8_t *buf, size_t buf_sz)
{
TEE_Result res = TEE_ERROR_GENERIC;
uint8_t *p = buf;
size_t sz = 0;
res = allocate_key();
if (res)
return res;
sz = deserialize_bignum(p, buf_sz, key->e);
if (!sz)
goto err;
p += sz;
buf_sz -= sz;
sz = deserialize_bignum(p, buf_sz, key->d);
if (!sz)
goto err;
p += sz;
buf_sz -= sz;
sz = deserialize_bignum(p, buf_sz, key->n);
if (!sz)
goto err;
return TEE_SUCCESS;
err:
free_key();
return TEE_ERROR_GENERIC;
}
static TEE_Result sec_storage_obj_read(TEE_UUID *uuid, uint32_t storage_id,
const uint8_t *obj_id,
size_t obj_id_len,
uint8_t *data, size_t *len,
size_t offset, uint32_t flags)
{
const struct tee_file_operations *fops = NULL;
TEE_Result res = TEE_ERROR_BAD_STATE;
struct tee_file_handle *fh = NULL;
struct tee_pobj *po = NULL;
size_t file_size = 0;
size_t read_len = 0;
fops = tee_svc_storage_file_ops(storage_id);
if (!fops)
return TEE_ERROR_NOT_IMPLEMENTED;
if (obj_id_len > TEE_OBJECT_ID_MAX_LEN)
return TEE_ERROR_BAD_PARAMETERS;
res = tee_pobj_get(uuid, (void *)obj_id, obj_id_len, flags, false, fops,
&po);
if (res)
return res;
res = po->fops->open(po, &file_size, &fh);
if (res)
goto out;
read_len = *len;
res = po->fops->read(fh, offset, data, &read_len);
if (res == TEE_ERROR_CORRUPT_OBJECT) {
EMSG("Object corrupt");
po->fops->remove(po);
} else if (!res) {
*len = read_len;
}
po->fops->close(&fh);
out:
tee_pobj_release(po);
return res;
}
static TEE_Result sec_storage_obj_write(TEE_UUID *uuid, uint32_t storage_id,
const uint8_t *obj_id,
size_t obj_id_len,
const uint8_t *data, size_t len,
size_t offset, uint32_t flags)
{
const struct tee_file_operations *fops = NULL;
struct tee_file_handle *fh = NULL;
TEE_Result res = TEE_SUCCESS;
struct tee_pobj *po = NULL;
fops = tee_svc_storage_file_ops(storage_id);
if (!fops)
return TEE_ERROR_NOT_IMPLEMENTED;
if (obj_id_len > TEE_OBJECT_ID_MAX_LEN)
return TEE_ERROR_BAD_PARAMETERS;
res = tee_pobj_get(uuid, (void *)obj_id, obj_id_len, flags, false,
fops, &po);
if (res)
return res;
res = po->fops->open(po, NULL, &fh);
if (res == TEE_ERROR_ITEM_NOT_FOUND)
res = po->fops->create(po, false, NULL, 0, NULL, 0, NULL, 0,
&fh);
if (!res) {
res = po->fops->write(fh, offset, data, len);
po->fops->close(&fh);
}
tee_pobj_release(po);
return res;
}
static TEE_Result load_key(uint8_t *buf, size_t size)
{
TEE_Result res = TEE_ERROR_GENERIC;
DMSG("Loading RSA key pair from secure storage");
res = sec_storage_obj_read(&pta_uuid, TEE_STORAGE_PRIVATE,
key_file_name, sizeof(key_file_name) - 1,
buf, &size, 0, TEE_DATA_FLAG_ACCESS_READ);
if (res)
return res;
DMSG("Read %zu bytes", size);
res = deserialize_key(buf, size);
if (!res)
DMSG("Loaded %zu bit key pair", crypto_bignum_num_bits(key->n));
return res;
}
static TEE_Result write_key(uint8_t *buf, size_t size)
{
TEE_Result res = TEE_ERROR_GENERIC;
DMSG("Saving key pair");
res = serialize_key(buf, size);
if (res)
return res;
res = sec_storage_obj_write(&pta_uuid, TEE_STORAGE_PRIVATE,
key_file_name, sizeof(key_file_name) - 1,
buf, size, 0, TEE_DATA_FLAG_ACCESS_WRITE);
if (!res)
DMSG("Wrote %zu bytes", size);
return res;
}
static TEE_Result init_key(void)
{
TEE_Result res = TEE_SUCCESS;
uint8_t *buf = NULL;
size_t size = 0;
if (!key) {
* e is 65537 so its bignum size is 3 bytes. d and n can be up
* to MAX_KEY_SIZE bits.
*/
size = bufsize(3, MAX_KEY_SIZE / 8, MAX_KEY_SIZE / 8);
buf = calloc(1, size);
if (!buf) {
res = TEE_ERROR_OUT_OF_MEMORY;
goto out;
}
res = load_key(buf, size);
if (res == TEE_ERROR_ITEM_NOT_FOUND) {
res = generate_key();
if (res)
goto out;
res = write_key(buf, size);
}
}
out:
free(buf);
return res;
}
static TEE_Result cmd_get_pubkey(uint32_t param_types,
TEE_Param params[TEE_NUM_PARAMS])
{
TEE_Result res = TEE_ERROR_GENERIC;
uint8_t *e = params[0].memref.buffer;
size_t *e_out_sz = ¶ms[0].memref.size;
uint8_t *n = params[1].memref.buffer;
size_t *n_out_sz = ¶ms[1].memref.size;
size_t sz = 0;
if (param_types != TEE_PARAM_TYPES(TEE_PARAM_TYPE_MEMREF_OUTPUT,
TEE_PARAM_TYPE_MEMREF_OUTPUT,
TEE_PARAM_TYPE_VALUE_OUTPUT,
TEE_PARAM_TYPE_NONE))
return TEE_ERROR_BAD_PARAMETERS;
res = init_key();
if (res)
return res;
sz = crypto_bignum_num_bytes(key->e);
if (*e_out_sz >= sz)
crypto_bignum_bn2bin(key->e, e);
else
res = TEE_ERROR_SHORT_BUFFER;
*e_out_sz = sz;
sz = crypto_bignum_num_bytes(key->n);
if (*n_out_sz >= sz)
crypto_bignum_bn2bin(key->n, n);
else
res = TEE_ERROR_SHORT_BUFFER;
*n_out_sz = sz;
params[2].value.a = TEE_ALG_RSASSA_PKCS1_PSS_MGF1_SHA256;
return res;
}
static TEE_Result hash_binary(const TEE_UUID *uuid, uint8_t *hash)
{
TEE_Result res = TEE_ERROR_ITEM_NOT_FOUND;
unsigned int tag_len = FILE_TAG_SIZE;
const struct ts_store_ops *ops = NULL;
struct ts_store_handle *h = NULL;
SCATTERED_ARRAY_FOREACH(ops, ta_stores, struct ts_store_ops) {
res = ops->open(uuid, &h);
if (!res)
break;
}
if (res)
return res;
* Output hash size is assumed to be the same size as the file tag
* size which is the size of the digest in the TA shdr. If one or the
* other changes, additional hashing will be needed.
*/
COMPILE_TIME_ASSERT(FILE_TAG_SIZE == TEE_SHA256_HASH_SIZE);
assert(ops);
res = ops->get_tag(h, hash, &tag_len);
if (res)
goto out;
DMSG("TA %pUl hash:", uuid);
DHEXDUMP(hash, TEE_SHA256_HASH_SIZE);
out:
ops->close(h);
return res;
}
static TEE_Result digest_nonce_and_hash(uint8_t *digest, uint8_t *nonce,
size_t nonce_sz, uint8_t *hash)
{
TEE_Result res = TEE_SUCCESS;
void *ctx = NULL;
res = crypto_hash_alloc_ctx(&ctx, TEE_ALG_SHA256);
if (res)
return res;
res = crypto_hash_init(ctx);
if (res)
goto out;
res = crypto_hash_update(ctx, nonce, nonce_sz);
if (res)
goto out;
res = crypto_hash_update(ctx, hash, TEE_SHA256_HASH_SIZE);
if (res)
goto out;
res = crypto_hash_final(ctx, digest, TEE_SHA256_HASH_SIZE);
out:
crypto_hash_free_ctx(ctx);
return res;
}
static TEE_Result sign_digest(uint8_t *sig, size_t sig_len,
const uint8_t *digest)
{
return crypto_acipher_rsassa_sign(TEE_ALG_RSASSA_PKCS1_PSS_MGF1_SHA256,
key,
TEE_SHA256_HASH_SIZE,
digest, TEE_SHA256_HASH_SIZE,
sig, &sig_len);
}
* Sign the first 32 bytes contained in @buf and append signature
* out = [ hash | sig(sha256(nonce | hash)) ]
* ^^^^ ^^^^^^^^^^^^^^^^^^^^^^^^^
* 32B modulus size
*/
static TEE_Result sign_buffer(uint8_t *buf, size_t buf_sz, uint8_t *nonce,
size_t nonce_sz)
{
uint8_t digest[TEE_SHA256_HASH_SIZE] = { };
TEE_Result res = TEE_SUCCESS;
res = digest_nonce_and_hash(digest, nonce, nonce_sz, buf);
if (res)
return res;
return sign_digest(buf + TEE_SHA256_HASH_SIZE,
buf_sz - TEE_SHA256_HASH_SIZE, digest);
}
* Is region valid for hashing?
* Exclude writable regions as well as those that are not specific to the TA
* (ldelf, kernel or temporary mappings).
*/
static bool is_region_valid(struct vm_region *r)
{
uint32_t skip_flags = VM_FLAG_EPHEMERAL | VM_FLAG_PERMANENT |
VM_FLAG_LDELF;
return !(r->flags & skip_flags || r->attr & TEE_MATTR_UW);
}
* With this comparison function, we're hashing the smaller regions first.
* Regions of equal size are ordered based on their content (memcmp()).
* Identical regions can be in any order since they will yield the same hash
* anyways.
*/
static int cmp_regions(const void *a, const void *b)
{
const struct vm_region *r1 = *(const struct vm_region **)a;
const struct vm_region *r2 = *(const struct vm_region **)b;
if (r1->size < r2->size)
return -1;
if (r1->size > r2->size)
return 1;
return memcmp((void *)r1->va, (void *)r2->va, r1->size);
}
static TEE_Result hash_regions(struct vm_info *vm_info, uint8_t *hash)
{
TEE_Result res = TEE_SUCCESS;
struct vm_region *r = NULL;
struct vm_region **regions = NULL;
size_t nregions = 0;
void *ctx = NULL;
size_t i = 0;
res = crypto_hash_alloc_ctx(&ctx, TEE_ALG_SHA256);
if (res)
return res;
res = crypto_hash_init(ctx);
if (res)
goto out;
* Make an array of region pointers so we can use qsort() to order it.
*/
TAILQ_FOREACH(r, &vm_info->regions, link)
if (is_region_valid(r))
nregions++;
regions = malloc(nregions * sizeof(*regions));
if (!regions) {
res = TEE_ERROR_OUT_OF_MEMORY;
goto out;
}
TAILQ_FOREACH(r, &vm_info->regions, link)
if (is_region_valid(r))
regions[i++] = r;
* Sort regions so that they are in a consistent order even when TA ASLR
* is enabled.
*/
qsort(regions, nregions, sizeof(*regions), cmp_regions);
for (i = 0; i < nregions; i++) {
r = regions[i];
DMSG("va %p size %zu", (void *)r->va, r->size);
res = crypto_hash_update(ctx, (uint8_t *)r->va, r->size);
if (res)
goto out;
}
res = crypto_hash_final(ctx, hash, TEE_SHA256_HASH_SIZE);
out:
free(regions);
crypto_hash_free_ctx(ctx);
return res;
}
static TEE_Result cmd_get_ta_shdr_digest(uint32_t param_types,
TEE_Param params[TEE_NUM_PARAMS])
{
TEE_UUID *uuid = params[0].memref.buffer;
size_t uuid_sz = params[0].memref.size;
uint8_t *nonce = params[1].memref.buffer;
size_t nonce_sz = params[1].memref.size;
uint8_t *out = params[2].memref.buffer;
size_t out_sz = params[2].memref.size;
size_t min_out_sz = 0;
TEE_Result res = TEE_SUCCESS;
if (param_types != TEE_PARAM_TYPES(TEE_PARAM_TYPE_MEMREF_INPUT,
TEE_PARAM_TYPE_MEMREF_INPUT,
TEE_PARAM_TYPE_MEMREF_OUTPUT,
TEE_PARAM_TYPE_NONE))
return TEE_ERROR_BAD_PARAMETERS;
if (uuid_sz != sizeof(*uuid))
return TEE_ERROR_BAD_PARAMETERS;
if (!nonce || !nonce_sz)
return TEE_ERROR_BAD_PARAMETERS;
if (!out && out_sz)
return TEE_ERROR_BAD_PARAMETERS;
res = init_key();
if (res)
return res;
min_out_sz = TEE_SHA256_HASH_SIZE + crypto_bignum_num_bytes(key->n);
params[2].memref.size = min_out_sz;
if (out_sz < min_out_sz)
return TEE_ERROR_SHORT_BUFFER;
out_sz = min_out_sz;
res = hash_binary(uuid, out);
if (res)
return res;
return sign_buffer(out, out_sz, nonce, nonce_sz);
}
static TEE_Result cmd_hash_ta_memory(uint32_t param_types,
TEE_Param params[TEE_NUM_PARAMS])
{
uint8_t *nonce = params[0].memref.buffer;
size_t nonce_sz = params[0].memref.size;
uint8_t *out = params[1].memref.buffer;
size_t out_sz = params[1].memref.size;
struct user_mode_ctx *uctx = NULL;
TEE_Result res = TEE_SUCCESS;
struct ts_session *s = NULL;
size_t min_out_sz = 0;
if (param_types != TEE_PARAM_TYPES(TEE_PARAM_TYPE_MEMREF_INPUT,
TEE_PARAM_TYPE_MEMREF_OUTPUT,
TEE_PARAM_TYPE_NONE,
TEE_PARAM_TYPE_NONE))
return TEE_ERROR_BAD_PARAMETERS;
if (!nonce || !nonce_sz)
return TEE_ERROR_BAD_PARAMETERS;
if (!out && out_sz)
return TEE_ERROR_BAD_PARAMETERS;
s = ts_get_calling_session();
if (!s)
return TEE_ERROR_ACCESS_DENIED;
uctx = to_user_mode_ctx(s->ctx);
if (!uctx)
return TEE_ERROR_ACCESS_DENIED;
res = init_key();
if (res)
return res;
min_out_sz = TEE_SHA256_HASH_SIZE + crypto_bignum_num_bytes(key->n);
params[1].memref.size = min_out_sz;
if (out_sz < min_out_sz)
return TEE_ERROR_SHORT_BUFFER;
out_sz = min_out_sz;
s = ts_pop_current_session();
res = hash_regions(&uctx->vm_info, out);
ts_push_current_session(s);
if (res)
return res;
return sign_buffer(out, out_sz, nonce, nonce_sz);
}
static TEE_Result cmd_hash_tee_memory(uint32_t param_types,
TEE_Param params[TEE_NUM_PARAMS])
{
uint8_t *nonce = params[0].memref.buffer;
size_t nonce_sz = params[0].memref.size;
uint8_t *out = params[1].memref.buffer;
size_t out_sz = params[1].memref.size;
TEE_Result res = TEE_SUCCESS;
size_t min_out_sz = 0;
void *ctx = NULL;
if (param_types != TEE_PARAM_TYPES(TEE_PARAM_TYPE_MEMREF_INPUT,
TEE_PARAM_TYPE_MEMREF_OUTPUT,
TEE_PARAM_TYPE_NONE,
TEE_PARAM_TYPE_NONE))
return TEE_ERROR_BAD_PARAMETERS;
if (!nonce || !nonce_sz)
return TEE_ERROR_BAD_PARAMETERS;
if (!out && out_sz)
return TEE_ERROR_BAD_PARAMETERS;
res = init_key();
if (res)
return res;
min_out_sz = TEE_SHA256_HASH_SIZE + crypto_bignum_num_bytes(key->n);
params[1].memref.size = min_out_sz;
if (out_sz < min_out_sz)
return TEE_ERROR_SHORT_BUFFER;
out_sz = min_out_sz;
res = crypto_hash_alloc_ctx(&ctx, TEE_ALG_SHA256);
if (res)
return res;
res = crypto_hash_init(ctx);
if (res)
goto out;
res = crypto_hash_update(ctx, __text_start,
__text_data_start - __text_start);
if (res)
goto out;
res = crypto_hash_update(ctx, __text_data_end,
__text_end - __text_data_end);
if (IS_ENABLED(CFG_WITH_PAGER)) {
res = crypto_hash_update(ctx, __text_init_start,
__text_init_end - __text_init_start);
if (res)
goto out;
res = crypto_hash_update(ctx, __text_pageable_start,
__text_pageable_end -
__text_pageable_start);
if (res)
goto out;
}
if (res)
goto out;
res = crypto_hash_update(ctx, __rodata_start,
__rodata_end - __rodata_start);
if (res)
goto out;
if (IS_ENABLED(CFG_WITH_PAGER)) {
res = crypto_hash_update(ctx, __rodata_init_start,
__rodata_init_end -
__rodata_init_start);
if (res)
goto out;
res = crypto_hash_update(ctx, __rodata_pageable_start,
__rodata_pageable_end -
__rodata_pageable_start);
if (res)
goto out;
}
res = crypto_hash_final(ctx, out, TEE_SHA256_HASH_SIZE);
if (res)
goto out;
DHEXDUMP(out, TEE_SHA256_HASH_SIZE);
res = sign_buffer(out, out_sz, nonce, nonce_sz);
out:
crypto_hash_free_ctx(ctx);
return res;
}
static TEE_Result invoke_command(void *sess_ctx __unused, uint32_t cmd_id,
uint32_t param_types,
TEE_Param params[TEE_NUM_PARAMS])
{
switch (cmd_id) {
case PTA_ATTESTATION_GET_PUBKEY:
return cmd_get_pubkey(param_types, params);
case PTA_ATTESTATION_GET_TA_SHDR_DIGEST:
return cmd_get_ta_shdr_digest(param_types, params);
case PTA_ATTESTATION_HASH_TA_MEMORY:
return cmd_hash_ta_memory(param_types, params);
case PTA_ATTESTATION_HASH_TEE_MEMORY:
return cmd_hash_tee_memory(param_types, params);
default:
break;
}
return TEE_ERROR_BAD_PARAMETERS;
}
pseudo_ta_register(.uuid = PTA_ATTESTATION_UUID, .name = PTA_NAME,
.flags = PTA_DEFAULT_FLAGS,
.invoke_command_entry_point = invoke_command);