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feat(core): introduce streaming access to storage items

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[no changelog]
pull/3604/head
tychovrahe 2 months ago
parent 1909d1ebdb
commit 832e2c1452
5 changed files with 155 additions and 27 deletions
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131
storage/storage.c
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@ -170,8 +170,10 @@ static secbool storage_upgrade_unlocked(const uint8_t *pin, size_t pin_len,
const uint8_t *ext_salt);
static secbool storage_set_encrypted(const uint16_t key, const void *val,
const uint16_t len);
static secbool storage_get_encrypted(const uint16_t key, void *val_dest,
const uint16_t max_len, uint16_t *len);
static secbool storage_get_encrypted(const uint16_t key, const uint16_t offset,
void *val_dest, const uint16_t max_len,
uint16_t *len, uint16_t *slice_len,
secbool slice);
#include "flash.h"
#ifdef FLASH_BIT_ACCESS
@ -763,8 +765,8 @@ static uint32_t get_lock_version(void) {
secbool check_storage_version(void) {
uint32_t version = 0;
uint16_t len = 0;
if (sectrue !=
storage_get_encrypted(VERSION_KEY, &version, sizeof(version), &len) ||
if (sectrue != storage_get_encrypted(VERSION_KEY, 0, &version,
sizeof(version), &len, NULL, secfalse) ||
len != sizeof(version)) {
handle_fault("storage version check");
return secfalse;
@ -1002,40 +1004,85 @@ secbool storage_unlock(const uint8_t *pin, size_t pin_len,
* If val_dest is not NULL and max_len >= len, then the data is decrypted
* to val_dest using cached_dek as the decryption key.
*/
static secbool storage_get_encrypted(const uint16_t key, void *val_dest,
const uint16_t max_len, uint16_t *len) {
static secbool storage_get_encrypted(const uint16_t key, const uint16_t offset,
void *val_dest, const uint16_t max_len,
uint16_t *total_len, uint16_t *slice_len,
secbool slice) {
const void *val_stored = NULL;
if (sectrue != auth_get(key, &val_stored, len)) {
if (sectrue != auth_get(key, &val_stored, total_len)) {
return secfalse;
}
if (*len < CHACHA20_IV_SIZE + POLY1305_TAG_SIZE) {
if (*total_len < CHACHA20_IV_SIZE + POLY1305_TAG_SIZE) {
handle_fault("ciphertext length check");
return secfalse;
}
*len -= CHACHA20_IV_SIZE + POLY1305_TAG_SIZE;
*total_len -= CHACHA20_IV_SIZE + POLY1305_TAG_SIZE;
if (val_dest == NULL) {
return sectrue;
}
if (*len > max_len) {
return secfalse;
if (slice) {
if (*total_len < offset) {
return secfalse;
}
} else {
if (*total_len > max_len) {
return secfalse;
}
}
uint16_t remaining_len = *total_len - offset;
uint16_t copy_remaining = remaining_len > max_len ? max_len : remaining_len;
uint16_t dest_offset = 0;
uint16_t src_offset = 0;
uint16_t copy_data_start = offset;
uint16_t copy_data_end = offset + copy_remaining;
const uint8_t *iv = (const uint8_t *)val_stored;
const uint8_t *tag_stored =
(const uint8_t *)val_stored + CHACHA20_IV_SIZE + *len;
(const uint8_t *)val_stored + CHACHA20_IV_SIZE + *total_len;
const uint8_t *ciphertext = (const uint8_t *)val_stored + CHACHA20_IV_SIZE;
uint8_t tag_computed[POLY1305_TAG_SIZE] = {0};
chacha20poly1305_ctx ctx = {0};
rfc7539_init(&ctx, cached_dek, iv);
rfc7539_auth(&ctx, (const uint8_t *)&key, sizeof(key));
chacha20poly1305_decrypt(&ctx, ciphertext, (uint8_t *)val_dest, *len);
rfc7539_finish(&ctx, sizeof(key), *len, tag_computed);
uint16_t tmp_len = *total_len;
while (tmp_len > 0) {
uint8_t val_dest_block[CHACHA20_BLOCK_SIZE] = {0};
uint16_t decrypt_len =
tmp_len > CHACHA20_BLOCK_SIZE ? CHACHA20_BLOCK_SIZE : tmp_len;
chacha20poly1305_decrypt(&ctx, ciphertext + src_offset, val_dest_block,
decrypt_len);
tmp_len -= decrypt_len;
if ((src_offset + decrypt_len) > copy_data_start &&
src_offset < copy_data_end) {
uint16_t dest_block_offset =
offset > src_offset ? offset - src_offset : 0;
uint16_t available = (decrypt_len - dest_block_offset);
uint16_t copy_len =
available > copy_remaining ? copy_remaining : available;
memcpy(((uint8_t *)val_dest) + dest_offset,
&val_dest_block[dest_block_offset], copy_len);
dest_offset += copy_len;
copy_remaining -= copy_len;
memzero(val_dest_block, sizeof(val_dest_block));
}
src_offset += decrypt_len;
}
rfc7539_finish(&ctx, sizeof(key), *total_len, tag_computed);
memzero(&ctx, sizeof(ctx));
if (slice_len != NULL) {
*slice_len = dest_offset;
}
// Verify authentication tag.
if (secequal(tag_computed, tag_stored, POLY1305_TAG_SIZE) != sectrue) {
memzero(val_dest, max_len);
@ -1053,12 +1100,10 @@ secbool storage_has(const uint16_t key) {
return storage_get(key, NULL, 0, &len);
}
/*
* Finds the data stored under key and writes its length to len. If val_dest is
* not NULL and max_len >= len, then the data is copied to val_dest.
*/
secbool storage_get(const uint16_t key, void *val_dest, const uint16_t max_len,
uint16_t *len) {
static secbool storage_get_uni(const uint16_t key, uint16_t offset,
void *val_dest, const uint16_t max_len,
uint16_t *total_len, uint16_t *slice_len,
secbool slice) {
const uint8_t app = key >> 8;
// APP == 0 is reserved for PIN related values
if (sectrue != initialized || app == APP_STORAGE) {
@ -1069,25 +1114,57 @@ secbool storage_get(const uint16_t key, void *val_dest, const uint16_t max_len,
// read from a locked device.
if ((app & FLAG_PUBLIC) != 0) {
const void *val_stored = NULL;
if (sectrue != norcow_get(key, &val_stored, len)) {
if (sectrue != norcow_get(key, &val_stored, total_len)) {
return secfalse;
}
if (val_dest == NULL) {
return sectrue;
}
if (*len > max_len) {
return secfalse;
if (slice) {
if (*total_len < offset) {
return secfalse;
}
} else {
if (*total_len > max_len) {
return secfalse;
}
}
memcpy(val_dest, val_stored, *len);
uint16_t remaining_len = *total_len - offset;
uint16_t copy_len = remaining_len > max_len ? max_len : remaining_len;
memcpy(val_dest, ((uint8_t *)val_stored) + offset, copy_len);
if (slice_len != NULL) {
*slice_len = copy_len;
}
return sectrue;
} else {
if (sectrue != unlocked) {
return secfalse;
}
return storage_get_encrypted(key, val_dest, max_len, len);
return storage_get_encrypted(key, offset, val_dest, max_len, total_len,
slice_len, slice);
}
}
secbool storage_get_slice(const uint16_t key, uint16_t offset, void *val_dest,
const uint16_t max_len, uint16_t *total_len,
uint16_t *slice_len) {
return storage_get_uni(key, offset, val_dest, max_len, total_len, slice_len,
sectrue);
}
/*
* Finds the data stored under key and writes its length to len. If val_dest is
* not NULL and max_len >= len, then the data is copied to val_dest.
*/
secbool storage_get(const uint16_t key, void *val_dest, const uint16_t max_len,
uint16_t *len) {
return storage_get_uni(key, 0, val_dest, max_len, len, NULL, secfalse);
}
/*
* Encrypts the data at val using cached_dek as the encryption key and stores
* the ciphertext under key.
@ -1592,8 +1669,8 @@ static secbool storage_upgrade_unlocked(const uint8_t *pin, size_t pin_len,
const uint8_t *ext_salt) {
uint32_t version = 0;
uint16_t len = 0;
if (sectrue !=
storage_get_encrypted(VERSION_KEY, &version, sizeof(version), &len) ||
if (sectrue != storage_get_encrypted(VERSION_KEY, 0, &version,
sizeof(version), &len, NULL, secfalse) ||
len != sizeof(version)) {
handle_fault("storage version check");
return secfalse;

3
storage/storage.h
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@ -79,6 +79,9 @@ secbool storage_change_wipe_code(const uint8_t *pin, size_t pin_len,
secbool storage_has(const uint16_t key);
secbool storage_get(const uint16_t key, void *val, const uint16_t max_len,
uint16_t *len);
secbool storage_get_slice(const uint16_t key, uint16_t offset, void *val,
const uint16_t max_len, uint16_t *total_len,
uint16_t *slice_len);
secbool storage_set(const uint16_t key, const void *val, const uint16_t len);
secbool storage_delete(const uint16_t key);
secbool storage_set_counter(const uint16_t key, const uint32_t count);

14
storage/tests/c/storage.py
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@ -74,6 +74,20 @@ class Storage:
raise RuntimeError("Failed to get value from storage.")
return s.raw
def get_slice(self, key: int, offset: int, len: int) -> bytes:
val_len = c.c_uint16()
slice_len = c.c_uint16()
if sectrue != self.lib.storage_get(c.c_uint16(key), None, 0, c.byref(val_len)):
raise RuntimeError("Failed to find key in storage.")
if len > val_len.value - offset > 0:
len = val_len.value - offset
s = c.create_string_buffer(len)
if sectrue != self.lib.storage_get_slice(
c.c_uint16(key), offset, s, len, c.byref(val_len), c.byref(slice_len)
):
raise RuntimeError("Failed to get value from storage.")
return s.raw
def set(self, key: int, val: bytes) -> None:
if sectrue != self.lib.storage_set(c.c_uint16(key), val, c.c_uint16(len(val))):
raise RuntimeError("Failed to set value in storage.")

8
storage/tests/python/src/storage.py
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@ -136,6 +136,14 @@ class Storage:
raise RuntimeError("Failed to find key in storage.")
return value
def get_slice(self, key: int, offset: int, max_len: int) -> bytes:
value = self.get(key)
if offset + max_len > len(value):
end = len(value)
else:
end = offset + max_len
return value[offset:end]
def set(self, key: int, val: bytes) -> bool:
app = key >> 8
self._check_lock(app)

26
storage/tests/tests/test_set_get.py
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@ -284,3 +284,29 @@ def test_counter(nc_class):
s.next_counter(0xC001)
assert common.memory_equals(sc, sp)
@pytest.mark.parametrize("nc_class", NC_CLASSES)
def test_streaming(nc_class):
sc, sp = common.init(nc_class, unlock=True)
test_data = [
b"HelloString",
b"HelloSomeVeryVeryVeryVeryLongString",
bytes([j % 256 for j in range(0, 133)]),
]
for s in (sc, sp):
for data in test_data:
s.set(0x0101, data)
s.set(0x8102, data)
for j in range(1, len(data)):
for i in range(0, len(data), j):
assert s.get_slice(0x0101, i, j) == data[i : i + j]
for j in range(1, len(data)):
for i in range(0, len(data), j):
assert s.get_slice(0x8102, i, j) == data[i : i + j]

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