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// Copyright 2015 The Weave Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "src/macaroon.h"
#include <string.h>
#include "src/crypto_utils.h"
#include "src/macaroon_caveat.h"
#include "src/macaroon_encoding.h"
static bool create_mac_tag_(const uint8_t* key, size_t key_len,
const UwMacaroonCaveat* caveats, size_t num_caveats,
uint8_t mac_tag[UW_MACAROON_MAC_LEN]) {
if (key == NULL || key_len == 0 || caveats == NULL || num_caveats == 0 ||
mac_tag == NULL) {
return false;
}
// Store the intermediate MAC tags in an internal buffer before we finish the
// whole computation.
// If we use the output buffer mac_tag directly and certain errors happen in
// the middle of this computation, mac_tag will probably contain a valid
// macaroon tag with large scope than expected.
uint8_t mac_tag_buff[UW_MACAROON_MAC_LEN];
// Compute the first tag by using the key
if (!uw_macaroon_caveat_sign_(key, key_len, &(caveats[0]), mac_tag_buff,
UW_MACAROON_MAC_LEN)) {
return false;
}
// Compute the rest of the tags by using the tag as the key
for (size_t i = 1; i < num_caveats; i++) {
if (!uw_macaroon_caveat_sign_(mac_tag_buff, UW_MACAROON_MAC_LEN,
&(caveats[i]), mac_tag_buff,
UW_MACAROON_MAC_LEN)) {
return false;
}
}
memcpy(mac_tag, mac_tag_buff, UW_MACAROON_MAC_LEN);
return true;
}
bool uw_macaroon_new_from_mac_tag_(UwMacaroon* new_macaroon,
const uint8_t mac_tag[UW_MACAROON_MAC_LEN],
const UwMacaroonCaveat* caveats,
size_t num_caveats) {
if (new_macaroon == NULL || mac_tag == NULL || caveats == NULL ||
num_caveats == 0) {
return false;
}
memcpy(new_macaroon->mac_tag, mac_tag, UW_MACAROON_MAC_LEN);
new_macaroon->num_caveats = num_caveats;
new_macaroon->caveats = caveats;
return true;
}
bool uw_macaroon_new_from_root_key_(UwMacaroon* new_macaroon,
const uint8_t* root_key,
size_t root_key_len,
const UwMacaroonCaveat* caveats,
size_t num_caveats) {
if (new_macaroon == NULL || root_key == NULL || root_key_len == 0 ||
caveats == NULL || num_caveats == 0) {
return false;
}
if (!create_mac_tag_(root_key, root_key_len, caveats, num_caveats,
new_macaroon->mac_tag)) {
return false;
}
new_macaroon->num_caveats = num_caveats;
new_macaroon->caveats = caveats;
return true;
}
bool uw_macaroon_verify_(const UwMacaroon* macaroon,
const uint8_t* root_key,
size_t root_key_len) {
if (macaroon == NULL || root_key == NULL) {
return false;
}
uint8_t mac_tag[UW_MACAROON_MAC_LEN] = {0};
if (!create_mac_tag_(root_key, root_key_len, macaroon->caveats,
macaroon->num_caveats, mac_tag)) {
return false;
}
return uw_crypto_utils_equal_(mac_tag, macaroon->mac_tag,
UW_MACAROON_MAC_LEN);
}
bool uw_macaroon_extend_(const UwMacaroon* old_macaroon,
UwMacaroon* new_macaroon,
const UwMacaroonCaveat* additional_caveat,
uint8_t* buffer, size_t buffer_size) {
if (old_macaroon == NULL || new_macaroon == NULL ||
additional_caveat == NULL || buffer == NULL || buffer_size == 0) {
return false;
}
new_macaroon->num_caveats = old_macaroon->num_caveats + 1;
// Extend the caveat list
if ((new_macaroon->num_caveats) * sizeof(UwMacaroonCaveat) > buffer_size) {
// Not enough memory to store the extended caveat list
return false;
}
UwMacaroonCaveat* extended_list = (UwMacaroonCaveat*)buffer;
if (old_macaroon->caveats != NULL && extended_list != old_macaroon->caveats) {
memcpy(extended_list, old_macaroon->caveats,
(old_macaroon->num_caveats) * sizeof(UwMacaroonCaveat));
}
extended_list[old_macaroon->num_caveats] = *additional_caveat;
new_macaroon->caveats = extended_list;
// Compute the new MAC tag
return create_mac_tag_(old_macaroon->mac_tag, UW_MACAROON_MAC_LEN,
additional_caveat, 1, new_macaroon->mac_tag);
}
// Encode a Macaroon to a byte string
bool uw_macaroon_dump_(const UwMacaroon* macaroon,
uint8_t* out,
size_t out_len,
size_t* resulting_str_len) {
if (macaroon == NULL || out == NULL || out_len == 0 ||
resulting_str_len == NULL) {
return false;
}
size_t offset = 0, item_len;
if (!uw_macaroon_encoding_encode_byte_str_(
macaroon->mac_tag, UW_MACAROON_MAC_LEN, out, out_len, &item_len)) {
return false;
}
offset += item_len;
if (!uw_macaroon_encoding_encode_array_len_(
(uint32_t)(macaroon->num_caveats), out + offset, out_len - offset, &item_len)) {
return false;
}
offset += item_len;
for (size_t i = 0; i < macaroon->num_caveats; i++) {
if (!uw_macaroon_encoding_encode_byte_str_(
macaroon->caveats[i].bytes, macaroon->caveats[i].num_bytes,
out + offset, out_len - offset, &item_len)) {
return false;
}
offset += item_len;
}
*resulting_str_len = offset;
return true;
}
// Decode a byte string to a Macaroon
bool uw_macaroon_load_(const uint8_t* in,
size_t in_len,
uint8_t* caveats_buffer,
size_t caveats_buffer_size,
UwMacaroon* macaroon) {
if (in == NULL || in_len == 0 || caveats_buffer == NULL ||
caveats_buffer_size == 0 || macaroon == NULL) {
return false;
}
const uint8_t* tag;
size_t tag_len;
if (!uw_macaroon_encoding_decode_byte_str_(in, in_len, &tag, &tag_len) ||
tag_len != UW_MACAROON_MAC_LEN) {
return false;
}
memcpy(macaroon->mac_tag, tag, UW_MACAROON_MAC_LEN);
size_t offset = 0, cbor_item_len;
if (!uw_macaroon_encoding_get_item_len_(in, in_len, &cbor_item_len)) {
return false;
}
offset += cbor_item_len;
uint32_t array_len;
if (!uw_macaroon_encoding_decode_array_len_(in + offset, in_len - offset,
&array_len)) {
return false;
}
macaroon->num_caveats = (size_t)array_len;
if (caveats_buffer_size < array_len * sizeof(UwMacaroonCaveat)) {
return false;
}
UwMacaroonCaveat* caveats = (UwMacaroonCaveat*)caveats_buffer;
for (size_t i = 0; i < array_len; i++) {
if (!uw_macaroon_encoding_get_item_len_(in + offset, in_len - offset,
&cbor_item_len)) {
return false;
}
offset += cbor_item_len;
if (!uw_macaroon_encoding_decode_byte_str_(in + offset, in_len - offset,
&(caveats[i].bytes),
&(caveats[i].num_bytes))) {
return false;
}
}
macaroon->caveats = caveats;
return true;
}
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