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protected_files.c
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protected_files.c
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/* SPDX-License-Identifier: LGPL-3.0-or-later */
/* Copyright (C) 2019-2020 Invisible Things Lab
* Rafal Wojdyla <omeg@invisiblethingslab.com>
* Copyright (C) 2011-2019 Intel Corporation
*/
#ifndef IN_PAL
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define USE_STDLIB
#endif
#include "protected_files.h"
#include "protected_files_format.h"
#include "protected_files_internal.h"
#include "api.h"
/* Function for scrubbing sensitive memory buffers.
* memset() can be optimized away and memset_s() is not available in PAL.
* FIXME: this implementation is inefficient (and used in perf-critical functions),
* replace with a better one.
* TODO: is this really needed? Intel's implementation uses similar function as "defense in depth".
*/
static void erase_memory(void* buffer, size_t size) {
volatile unsigned char* p = buffer;
while (size--)
*p++ = 0;
}
/* Host callbacks */
static pf_read_f g_cb_read = NULL;
static pf_write_f g_cb_write = NULL;
static pf_truncate_f g_cb_truncate = NULL;
static pf_debug_f g_cb_debug = NULL;
static pf_aes_gcm_encrypt_f g_cb_aes_gcm_encrypt = NULL;
static pf_aes_gcm_decrypt_f g_cb_aes_gcm_decrypt = NULL;
static pf_random_f g_cb_random = NULL;
#ifdef DEBUG
#define PF_DEBUG_PRINT_SIZE_MAX 4096
/* Debug print without function name prefix. Implicit param: pf (context pointer). */
#define __DEBUG_PF(format, ...) \
do { \
if (g_cb_debug) { \
snprintf(pf->debug_buffer, PF_DEBUG_PRINT_SIZE_MAX, format, ##__VA_ARGS__); \
g_cb_debug(pf->debug_buffer); \
} \
} while (0)
/* Debug print with function name prefix. Implicit param: pf (context pointer). */
#define DEBUG_PF(format, ...) \
do { \
if (g_cb_debug) { \
snprintf(pf->debug_buffer, PF_DEBUG_PRINT_SIZE_MAX, "%s: " format, __FUNCTION__, \
##__VA_ARGS__); \
g_cb_debug(pf->debug_buffer); \
} \
} while (0)
#else /* DEBUG */
#define DEBUG_PF(...)
#define __DEBUG_PF(...)
#endif /* DEBUG */
static pf_iv_t g_empty_iv = {0};
static bool g_initialized = false;
// The key derivation function follow recommendations from NIST Special Publication 800-108:
// Recommendation for Key Derivation Using Pseudorandom Functions
// https://nvlpubs.nist.gov/nistpubs/Legacy/SP/nistspecialpublication800-108.pdf
// derive a metadata key from user key (if restore is false, the derived key is randomized)
static bool ipf_import_metadata_key(pf_context_t* pf, bool restore, pf_key_t* output) {
kdf_input_t buf = {0};
pf_status_t status;
buf.index = 1;
if (!strcpy_static(buf.label, METADATA_KEY_NAME, MAX_LABEL_SIZE))
return false;
if (!restore) {
status = g_cb_random((uint8_t*)&buf.nonce, sizeof(buf.nonce));
if (PF_FAILURE(status)) {
pf->last_error = status;
return false;
}
} else {
COPY_ARRAY(buf.nonce, pf->file_metadata.plain_part.metadata_key_id);
}
// length of output (128 bits)
buf.output_len = 0x80;
status = g_cb_aes_gcm_encrypt(&pf->user_kdk_key, &g_empty_iv, &buf, sizeof(buf), NULL, 0, NULL,
output);
if (PF_FAILURE(status)) {
pf->last_error = status;
return false;
}
if (!restore) {
COPY_ARRAY(pf->file_metadata.plain_part.metadata_key_id, buf.nonce);
}
erase_memory(&buf, sizeof(buf));
return true;
}
static bool ipf_generate_random_key(pf_context_t* pf, pf_key_t* output) {
pf_status_t status = g_cb_random((uint8_t*)output, sizeof(*output));
if (PF_FAILURE(status)) {
pf->last_error = status;
return false;
}
return true;
}
static bool ipf_generate_random_metadata_key(pf_context_t* pf, pf_key_t* output) {
return ipf_import_metadata_key(pf, /*restore=*/false, output);
}
static bool ipf_restore_current_metadata_key(pf_context_t* pf, pf_key_t* output) {
return ipf_import_metadata_key(pf, /*restore=*/true, output);
}
static bool ipf_init_fields(pf_context_t* pf) {
#ifdef DEBUG
pf->debug_buffer = malloc(PF_DEBUG_PRINT_SIZE_MAX);
if (!pf->debug_buffer) {
pf->last_error = PF_STATUS_NO_MEMORY;
return false;
}
#endif
memset(&pf->file_metadata, 0, sizeof(pf->file_metadata));
memset(&pf->encrypted_part_plain, 0, sizeof(pf->encrypted_part_plain));
memset(&g_empty_iv, 0, sizeof(g_empty_iv));
memset(&pf->root_mht, 0, sizeof(pf->root_mht));
pf->root_mht.type = FILE_MHT_NODE_TYPE;
pf->root_mht.physical_node_number = 1;
pf->root_mht.node_number = 0;
pf->root_mht.new_node = true;
pf->root_mht.need_writing = false;
pf->offset = 0;
pf->file = NULL;
pf->end_of_file = false;
pf->need_writing = false;
pf->file_status = PF_STATUS_UNINITIALIZED;
pf->last_error = PF_STATUS_SUCCESS;
pf->real_file_size = 0;
pf->cache = lruc_create();
return true;
}
static pf_context_t* ipf_open(const char* path, pf_file_mode_t mode, bool create, pf_handle_t file,
uint64_t real_size, const pf_key_t* kdk_key, pf_status_t* status) {
*status = PF_STATUS_NO_MEMORY;
pf_context_t* pf = calloc(1, sizeof(*pf));
if (!pf)
goto out;
if (!ipf_init_fields(pf))
goto out;
DEBUG_PF("handle: %d, path: '%s', real size: %lu, mode: 0x%x\n", *(int*)file, path, real_size,
mode);
if (kdk_key == NULL) {
DEBUG_PF("no key specified\n");
pf->last_error = PF_STATUS_INVALID_PARAMETER;
goto out;
}
if (path && strlen(path) > PATH_MAX_SIZE - 1) {
pf->last_error = PF_STATUS_PATH_TOO_LONG;
goto out;
}
// for new file, this value will later be saved in the meta data plain part (init_new_file)
// for existing file, we will later compare this value with the value from the file
// (init_existing_file)
COPY_ARRAY(pf->user_kdk_key, *kdk_key);
// omeg: we require a canonical full path to file, so no stripping path to filename only
// omeg: Intel's implementation opens the file, we get the fd and size from the Graphene handler
if (!file) {
DEBUG_PF("invalid handle\n");
pf->last_error = PF_STATUS_INVALID_PARAMETER;
goto out;
}
if (real_size % PF_NODE_SIZE != 0) {
pf->last_error = PF_STATUS_INVALID_HEADER;
goto out;
}
pf->file = file;
pf->real_file_size = real_size;
pf->mode = mode;
if (!create) {
// existing file
if (!ipf_init_existing_file(pf, path))
goto out;
} else {
// new file
if (!ipf_init_new_file(pf, path))
goto out;
}
pf->last_error = pf->file_status = PF_STATUS_SUCCESS;
DEBUG_PF("OK (data size %lu)\n", pf->encrypted_part_plain.size);
out:
if (pf && PF_FAILURE(pf->last_error)) {
DEBUG_PF("failed: %d\n", pf->last_error);
free(pf);
pf = NULL;
}
if (pf)
*status = pf->last_error;
return pf;
}
static bool ipf_read_node(pf_context_t* pf, pf_handle_t handle, uint64_t node_number, void* buffer,
uint32_t node_size) {
uint64_t offset = node_number * node_size;
pf_status_t status = g_cb_read(handle, buffer, offset, node_size);
if (PF_FAILURE(status)) {
pf->last_error = status;
return false;
}
return true;
}
static bool ipf_write_file(pf_context_t* pf, pf_handle_t handle, uint64_t offset, void* buffer,
uint32_t size) {
pf_status_t status = g_cb_write(handle, buffer, offset, size);
if (PF_FAILURE(status)) {
pf->last_error = status;
return false;
}
return true;
}
static bool ipf_write_node(pf_context_t* pf, pf_handle_t handle, uint64_t node_number, void* buffer,
uint32_t node_size) {
return ipf_write_file(pf, handle, node_number * node_size, buffer, node_size);
}
static bool ipf_init_existing_file(pf_context_t* pf, const char* path) {
pf_status_t status;
// read meta-data node
if (!ipf_read_node(pf, pf->file, /*node_number=*/0, (uint8_t*)&pf->file_metadata,
PF_NODE_SIZE)) {
return false;
}
if (pf->file_metadata.plain_part.file_id != PF_FILE_ID) {
// such a file exists, but it is not a protected file
pf->last_error = PF_STATUS_INVALID_HEADER;
return false;
}
if (pf->file_metadata.plain_part.major_version != PF_MAJOR_VERSION) {
pf->last_error = PF_STATUS_INVALID_VERSION;
return false;
}
pf_key_t key;
if (!ipf_restore_current_metadata_key(pf, &key))
return false;
// decrypt the encrypted part of the meta-data
status = g_cb_aes_gcm_decrypt(&key, &g_empty_iv, NULL, 0,
&pf->file_metadata.encrypted_part,
sizeof(pf->file_metadata.encrypted_part),
&pf->encrypted_part_plain,
&pf->file_metadata.plain_part.metadata_gmac);
if (PF_FAILURE(status)) {
pf->last_error = status;
DEBUG_PF("failed to decrypt metadata: %d\n", status);
return false;
}
DEBUG_PF("data size %lu\n", pf->encrypted_part_plain.size);
if (path) {
size_t path_len = strlen(pf->encrypted_part_plain.path);
if (path_len != strlen(path)
|| memcmp(path, pf->encrypted_part_plain.path, path_len) != 0) {
pf->last_error = PF_STATUS_INVALID_PATH;
return false;
}
}
if (pf->encrypted_part_plain.size > MD_USER_DATA_SIZE) {
// read the root node of the mht
if (!ipf_read_node(pf, pf->file, /*node_number=*/1, &pf->root_mht.encrypted.cipher,
PF_NODE_SIZE))
return false;
// this also verifies the root mht gmac against the gmac in the meta-data encrypted part
status = g_cb_aes_gcm_decrypt(&pf->encrypted_part_plain.mht_key, &g_empty_iv,
NULL, 0, // aad
&pf->root_mht.encrypted.cipher, PF_NODE_SIZE,
&pf->root_mht.decrypted.mht,
&pf->encrypted_part_plain.mht_gmac);
if (PF_FAILURE(status)) {
pf->last_error = status;
return false;
}
pf->root_mht.new_node = false;
}
return true;
}
static bool ipf_init_new_file(pf_context_t* pf, const char* path) {
pf->file_metadata.plain_part.file_id = PF_FILE_ID;
pf->file_metadata.plain_part.major_version = PF_MAJOR_VERSION;
pf->file_metadata.plain_part.minor_version = PF_MINOR_VERSION;
// path length is checked in ipf_open()
memcpy(pf->encrypted_part_plain.path, path, strlen(path) + 1);
pf->need_writing = true;
return true;
}
static bool ipf_close(pf_context_t* pf) {
void* data;
bool retval = true;
if (pf->file_status != PF_STATUS_SUCCESS) {
ipf_try_clear_error(pf); // last attempt to fix it
retval = false;
} else {
if (!ipf_internal_flush(pf)) {
DEBUG_PF("internal flush failed\n");
retval = false;
}
}
// omeg: fs close is done by Graphene handler
pf->file_status = PF_STATUS_UNINITIALIZED;
while ((data = lruc_get_last(pf->cache)) != NULL) {
file_node_t* file_node = (file_node_t*)data;
erase_memory(&file_node->decrypted, sizeof(file_node->decrypted));
free(file_node);
lruc_remove_last(pf->cache);
}
// scrub first MD_USER_DATA_SIZE of file data and the gmac_key
erase_memory(&pf->encrypted_part_plain, sizeof(pf->encrypted_part_plain));
lruc_destroy(pf->cache);
#ifdef DEBUG
free(pf->debug_buffer);
#endif
erase_memory(pf, sizeof(struct pf_context));
free(pf);
return retval;
}
static bool ipf_internal_flush(pf_context_t* pf) {
if (!pf->need_writing) {
// no changes at all
DEBUG_PF("no need to write\n");
return true;
}
if (pf->encrypted_part_plain.size > MD_USER_DATA_SIZE && pf->root_mht.need_writing) {
// otherwise it's just one write - the meta-data node
if (!ipf_update_all_data_and_mht_nodes(pf)) {
// this is something that shouldn't happen, can't fix this...
pf->file_status = PF_STATUS_CRYPTO_ERROR;
DEBUG_PF("failed to update data nodes\n");
return false;
}
}
if (!ipf_update_metadata_node(pf)) {
// this is something that shouldn't happen, can't fix this...
pf->file_status = PF_STATUS_CRYPTO_ERROR;
DEBUG_PF("failed to update metadata nodes\n");
return false;
}
if (!ipf_write_all_changes_to_disk(pf)) {
pf->file_status = PF_STATUS_WRITE_TO_DISK_FAILED;
DEBUG_PF("failed to write changes to disk\n");
return false;
}
pf->need_writing = false;
return true;
}
static void swap_nodes(file_node_t** data, size_t idx1, size_t idx2) {
file_node_t* tmp = data[idx1];
data[idx1] = data[idx2];
data[idx2] = tmp;
}
// TODO: better sort?
static size_t partition(file_node_t** data, size_t low, size_t high) {
assert(low <= high);
file_node_t* pivot = data[(low + high) / 2];
size_t i = low;
size_t j = high;
while (true) {
while (data[i]->node_number < pivot->node_number)
i++;
while (data[j]->node_number > pivot->node_number)
j--;
if (i >= j)
return j;
swap_nodes(data, i, j);
i++;
j--;
}
}
static void sort_nodes(file_node_t** data, size_t low, size_t high) {
if (high - low == 1) {
if (data[low]->node_number > data[high]->node_number)
swap_nodes(data, low, high);
return;
}
if (low < high) {
size_t pi = partition(data, low, high);
if (pi > 0)
sort_nodes(data, low, pi);
sort_nodes(data, pi + 1, high);
}
}
static bool ipf_update_all_data_and_mht_nodes(pf_context_t* pf) {
bool ret = false;
file_node_t** mht_array = NULL;
file_node_t* file_mht_node;
pf_status_t status;
void* data = lruc_get_first(pf->cache);
// 1. encrypt the changed data
// 2. set the IV+GMAC in the parent MHT
// [3. set the need_writing flag for all the parents]
while (data != NULL) {
if (((file_node_t*)data)->type == FILE_DATA_NODE_TYPE) {
file_node_t* data_node = (file_node_t*)data;
if (data_node->need_writing) {
gcm_crypto_data_t* gcm_crypto_data =
&data_node->parent->decrypted.mht
.data_nodes_crypto[data_node->node_number % ATTACHED_DATA_NODES_COUNT];
if (!ipf_generate_random_key(pf, &gcm_crypto_data->key))
goto out;
// encrypt the data, this also saves the gmac of the operation in the mht crypto
// node
status = g_cb_aes_gcm_encrypt(&gcm_crypto_data->key, &g_empty_iv, NULL, 0, // aad
data_node->decrypted.data.data, PF_NODE_SIZE,
data_node->encrypted.cipher, &gcm_crypto_data->gmac);
if (PF_FAILURE(status)) {
pf->last_error = status;
goto out;
}
file_mht_node = data_node->parent;
#ifdef DEBUG
// this loop should do nothing, add it here just to be safe
while (file_mht_node->node_number != 0) {
assert(file_mht_node->need_writing == true);
file_mht_node = file_mht_node->parent;
}
#endif
}
}
data = lruc_get_next(pf->cache);
}
size_t dirty_count = 0;
// count dirty mht nodes
data = lruc_get_first(pf->cache);
while (data != NULL) {
if (((file_node_t*)data)->type == FILE_MHT_NODE_TYPE) {
if (((file_node_t*)data)->need_writing)
dirty_count++;
}
data = lruc_get_next(pf->cache);
}
// add all the mht nodes that needs writing to a list
mht_array = malloc(dirty_count * sizeof(*mht_array));
if (!mht_array) {
pf->last_error = PF_STATUS_NO_MEMORY;
goto out;
}
data = lruc_get_first(pf->cache);
uint64_t dirty_idx = 0;
while (data != NULL) {
if (((file_node_t*)data)->type == FILE_MHT_NODE_TYPE) {
file_mht_node = (file_node_t*)data;
if (file_mht_node->need_writing)
mht_array[dirty_idx++] = file_mht_node;
}
data = lruc_get_next(pf->cache);
}
if (dirty_count > 0)
sort_nodes(mht_array, 0, dirty_count - 1);
// update the gmacs in the parents from last node to first (bottom layers first)
for (dirty_idx = dirty_count; dirty_idx > 0; dirty_idx--) {
file_mht_node = mht_array[dirty_idx - 1];
gcm_crypto_data_t* gcm_crypto_data =
&file_mht_node->parent->decrypted.mht
.mht_nodes_crypto[(file_mht_node->node_number - 1) % CHILD_MHT_NODES_COUNT];
if (!ipf_generate_random_key(pf, &gcm_crypto_data->key)) {
goto out;
}
status = g_cb_aes_gcm_encrypt(&gcm_crypto_data->key, &g_empty_iv, NULL, 0,
&file_mht_node->decrypted.mht, PF_NODE_SIZE,
&file_mht_node->encrypted.cipher, &gcm_crypto_data->gmac);
if (PF_FAILURE(status)) {
pf->last_error = status;
goto out;
}
}
// update mht root gmac in the meta data node
if (!ipf_generate_random_key(pf, &pf->encrypted_part_plain.mht_key))
goto out;
status = g_cb_aes_gcm_encrypt(&pf->encrypted_part_plain.mht_key, &g_empty_iv,
NULL, 0,
&pf->root_mht.decrypted.mht, PF_NODE_SIZE,
&pf->root_mht.encrypted.cipher,
&pf->encrypted_part_plain.mht_gmac);
if (PF_FAILURE(status)) {
pf->last_error = status;
goto out;
}
ret = true;
out:
free(mht_array);
return ret;
}
static bool ipf_update_metadata_node(pf_context_t* pf) {
pf_status_t status;
pf_key_t key;
// randomize a new key, saves the key _id_ in the meta data plain part
if (!ipf_generate_random_metadata_key(pf, &key)) {
// last error already set
return false;
}
// encrypt meta data encrypted part, also updates the gmac in the meta data plain part
status = g_cb_aes_gcm_encrypt(&key, &g_empty_iv, NULL, 0, &pf->encrypted_part_plain,
sizeof(metadata_encrypted_t), &pf->file_metadata.encrypted_part,
&pf->file_metadata.plain_part.metadata_gmac);
if (PF_FAILURE(status)) {
pf->last_error = status;
return false;
}
return true;
}
static bool ipf_write_all_changes_to_disk(pf_context_t* pf) {
if (pf->encrypted_part_plain.size > MD_USER_DATA_SIZE && pf->root_mht.need_writing) {
void* data = NULL;
uint8_t* data_to_write;
uint64_t node_number;
file_node_t* file_node;
for (data = lruc_get_first(pf->cache); data != NULL; data = lruc_get_next(pf->cache)) {
file_node = (file_node_t*)data;
if (!file_node->need_writing)
continue;
data_to_write = (uint8_t*)&file_node->encrypted;
node_number = file_node->physical_node_number;
if (!ipf_write_node(pf, pf->file, node_number, data_to_write, PF_NODE_SIZE)) {
return false;
}
file_node->need_writing = false;
file_node->new_node = false;
}
if (!ipf_write_node(pf, pf->file, /*node_number=*/1, &pf->root_mht.encrypted,
PF_NODE_SIZE)) {
return false;
}
pf->root_mht.need_writing = false;
pf->root_mht.new_node = false;
}
if (!ipf_write_node(pf, pf->file, /*node_number=*/0, &pf->file_metadata, PF_NODE_SIZE)) {
return false;
}
return true;
}
// seek to a specified file offset from the beginning
// seek beyond the current size is supported if the file is writable,
// the file is then extended with zeros (Intel SGX SDK implementation didn't support extending)
static bool ipf_seek(pf_context_t* pf, uint64_t new_offset) {
if (PF_FAILURE(pf->file_status)) {
pf->last_error = pf->file_status;
return false;
}
bool result = false;
if (new_offset <= pf->encrypted_part_plain.size) {
pf->offset = new_offset;
result = true;
} else if (pf->mode & PF_FILE_MODE_WRITE) {
// need to extend the file
result = PF_SUCCESS(pf_set_size(pf, new_offset));
}
if (result)
pf->end_of_file = false;
else
pf->last_error = PF_STATUS_INVALID_PARAMETER;
return result;
}
static void ipf_try_clear_error(pf_context_t* pf) {
if (pf->file_status == PF_STATUS_UNINITIALIZED ||
pf->file_status == PF_STATUS_CRYPTO_ERROR ||
pf->file_status == PF_STATUS_CORRUPTED) {
// can't fix these...
DEBUG_PF("Unrecoverable file status: %d\n", pf->file_status);
return;
}
if (pf->file_status == PF_STATUS_FLUSH_ERROR) {
if (ipf_internal_flush(pf))
pf->file_status = PF_STATUS_SUCCESS;
}
if (pf->file_status == PF_STATUS_WRITE_TO_DISK_FAILED) {
if (ipf_write_all_changes_to_disk(pf)) {
pf->need_writing = false;
pf->file_status = PF_STATUS_SUCCESS;
}
}
if (pf->file_status == PF_STATUS_SUCCESS) {
pf->last_error = PF_STATUS_SUCCESS;
pf->end_of_file = false;
}
}
// memcpy src->dest if src is not NULL, zero dest otherwise
static void memcpy_or_zero_initialize(void* dest, const void* src, size_t size) {
if (src)
memcpy(dest, src, size);
else
memset(dest, 0, size);
}
// write zeros if `ptr` is NULL
static size_t ipf_write(pf_context_t* pf, const void* ptr, size_t size) {
if (size == 0) {
pf->last_error = PF_STATUS_INVALID_PARAMETER;
return 0;
}
size_t data_left_to_write = size;
if (PF_FAILURE(pf->file_status)) {
pf->last_error = pf->file_status;
DEBUG_PF("bad file status %d\n", pf->last_error);
return 0;
}
if (!(pf->mode & PF_FILE_MODE_WRITE)) {
pf->last_error = PF_STATUS_INVALID_MODE;
DEBUG_PF("File is read-only\n");
return 0;
}
const unsigned char* data_to_write = (const unsigned char*)ptr;
// the first block of user data is written in the meta-data encrypted part
if (pf->offset < MD_USER_DATA_SIZE) {
// offset is smaller than MD_USER_DATA_SIZE
size_t empty_place_left_in_md = MD_USER_DATA_SIZE - (size_t)pf->offset;
size_t size_to_write = MIN(data_left_to_write, empty_place_left_in_md);
memcpy_or_zero_initialize(&pf->encrypted_part_plain.data[pf->offset], data_to_write,
size_to_write);
pf->offset += size_to_write;
if (data_to_write)
data_to_write += size_to_write;
data_left_to_write -= size_to_write;
if (pf->offset > pf->encrypted_part_plain.size)
pf->encrypted_part_plain.size = pf->offset; // file grew, update the new file size
pf->need_writing = true;
}
while (data_left_to_write > 0) {
file_node_t* file_data_node = NULL;
// return the data node of the current offset, will read it from disk or create new one
// if needed (and also the mht node if needed)
file_data_node = ipf_get_data_node(pf);
if (file_data_node == NULL) {
DEBUG_PF("failed to get data node\n");
break;
}
size_t offset_in_node = (size_t)((pf->offset - MD_USER_DATA_SIZE) % PF_NODE_SIZE);
size_t empty_place_left_in_node = PF_NODE_SIZE - offset_in_node;
size_t size_to_write = MIN(data_left_to_write, empty_place_left_in_node);
memcpy_or_zero_initialize(&file_data_node->decrypted.data.data[offset_in_node],
data_to_write, size_to_write);
pf->offset += size_to_write;
if (data_to_write)
data_to_write += size_to_write;
data_left_to_write -= size_to_write;
if (pf->offset > pf->encrypted_part_plain.size) {
pf->encrypted_part_plain.size = pf->offset; // file grew, update the new file size
}
if (!file_data_node->need_writing) {
file_data_node->need_writing = true;
file_node_t* file_mht_node = file_data_node->parent;
while (file_mht_node->node_number != 0) {
// set all the mht parent nodes as 'need writing'
file_mht_node->need_writing = true;
file_mht_node = file_mht_node->parent;
}
pf->root_mht.need_writing = true;
pf->need_writing = true;
}
}
return size - data_left_to_write;
}
static size_t ipf_read(pf_context_t* pf, void* ptr, size_t size) {
if (ptr == NULL) {
pf->last_error = PF_STATUS_INVALID_PARAMETER;
return 0;
}
if (PF_FAILURE(pf->file_status)) {
pf->last_error = pf->file_status;
return 0;
}
if (!(pf->mode & PF_FILE_MODE_READ)) {
pf->last_error = PF_STATUS_INVALID_MODE;
return 0;
}
size_t data_left_to_read = size;
if (((uint64_t)data_left_to_read) > (uint64_t)(pf->encrypted_part_plain.size - pf->offset)) {
// the request is bigger than what's left in the file
data_left_to_read = (size_t)(pf->encrypted_part_plain.size - pf->offset);
}
// used at the end to return how much we actually read
size_t data_attempted_to_read = data_left_to_read;
unsigned char* out_buffer = (unsigned char*)ptr;
// the first block of user data is read from the meta-data encrypted part
if (pf->offset < MD_USER_DATA_SIZE) {
// offset is smaller than MD_USER_DATA_SIZE
size_t data_left_in_md = MD_USER_DATA_SIZE - (size_t)pf->offset;
size_t size_to_read = MIN(data_left_to_read, data_left_in_md);
memcpy(out_buffer, &pf->encrypted_part_plain.data[pf->offset], size_to_read);
pf->offset += size_to_read;
out_buffer += size_to_read;
data_left_to_read -= size_to_read;
}
while (data_left_to_read > 0) {
file_node_t* file_data_node = NULL;
// return the data node of the current offset, will read it from disk if needed
// (and also the mht node if needed)
file_data_node = ipf_get_data_node(pf);
if (file_data_node == NULL)
break;
size_t offset_in_node = (pf->offset - MD_USER_DATA_SIZE) % PF_NODE_SIZE;
size_t data_left_in_node = PF_NODE_SIZE - offset_in_node;
size_t size_to_read = MIN(data_left_to_read, data_left_in_node);
memcpy(out_buffer, &file_data_node->decrypted.data.data[offset_in_node], size_to_read);
pf->offset += size_to_read;
out_buffer += size_to_read;
data_left_to_read -= size_to_read;
}
if (data_left_to_read == 0 && data_attempted_to_read != size) {
// user wanted to read more and we had to shrink the request
assert(pf->offset == pf->encrypted_part_plain.size);
pf->end_of_file = true;
}
return data_attempted_to_read - data_left_to_read;
}
// this is a very 'specific' function, tied to the architecture of the file layout,
// returning the node numbers according to the data offset in the file
static void get_node_numbers(uint64_t offset, uint64_t* mht_node_number, uint64_t* data_node_number,
uint64_t* physical_mht_node_number,
uint64_t* physical_data_node_number) {
// physical nodes (file layout):
// node 0 - meta data node
// node 1 - mht
// nodes 2-97 - data (ATTACHED_DATA_NODES_COUNT == 96)
// node 98 - mht
// node 99-195 - data
// etc.
uint64_t _physical_mht_node_number;
uint64_t _physical_data_node_number;
// "logical" nodes: sequential index of the corresponding mht/data node in all mht/data nodes
uint64_t _mht_node_number;
uint64_t _data_node_number;
assert(offset >= MD_USER_DATA_SIZE);
_data_node_number = (offset - MD_USER_DATA_SIZE) / PF_NODE_SIZE;
_mht_node_number = _data_node_number / ATTACHED_DATA_NODES_COUNT;
_physical_data_node_number = _data_node_number
+ 1 // meta data node
+ 1 // mht root
+ _mht_node_number; // number of mht nodes in the middle
// (the root mht mht_node_number is 0)
_physical_mht_node_number = _physical_data_node_number
- _data_node_number % ATTACHED_DATA_NODES_COUNT // now we are at
// the first data node attached to this mht node
- 1; // and now at the mht node itself!
if (mht_node_number != NULL)
*mht_node_number = _mht_node_number;
if (data_node_number != NULL)
*data_node_number = _data_node_number;
if (physical_mht_node_number != NULL)
*physical_mht_node_number = _physical_mht_node_number;
if (physical_data_node_number != NULL)
*physical_data_node_number = _physical_data_node_number;
}
static file_node_t* ipf_get_data_node(pf_context_t* pf) {
file_node_t* file_data_node = NULL;
if (pf->offset < MD_USER_DATA_SIZE) {
pf->last_error = PF_STATUS_UNKNOWN_ERROR;
return NULL;
}
if ((pf->offset - MD_USER_DATA_SIZE) % PF_NODE_SIZE == 0
&& pf->offset == pf->encrypted_part_plain.size) {
// new node
file_data_node = ipf_append_data_node(pf);
} else {
// existing node
file_data_node = ipf_read_data_node(pf);
}
// bump all the parents mht to reside before the data node in the cache
if (file_data_node != NULL) {
file_node_t* file_mht_node = file_data_node->parent;
while (file_mht_node->node_number != 0) {
// bump the mht node to the head of the lru
lruc_get(pf->cache, file_mht_node->physical_node_number);
file_mht_node = file_mht_node->parent;
}
}
// even if we didn't get the required data_node, we might have read other nodes in the process
while (lruc_size(pf->cache) > MAX_PAGES_IN_CACHE) {
void* data = lruc_get_last(pf->cache);
assert(data != NULL);
// for production -
if (data == NULL) {
pf->last_error = PF_STATUS_UNKNOWN_ERROR;
return NULL;
}
if (!((file_node_t*)data)->need_writing) {
lruc_remove_last(pf->cache);
// before deleting the memory, need to scrub the plain secrets
file_node_t* file_node = (file_node_t*)data;
erase_memory(&file_node->decrypted, sizeof(file_node->decrypted));
free(file_node);
} else {
if (!ipf_internal_flush(pf)) {
// error, can't flush cache, file status changed to error
assert(pf->file_status != PF_STATUS_SUCCESS);
if (pf->file_status == PF_STATUS_SUCCESS)
pf->file_status = PF_STATUS_FLUSH_ERROR; // for release set this anyway
return NULL; // even if we got the data_node!
}
}
}
return file_data_node;
}
static file_node_t* ipf_append_data_node(pf_context_t* pf) {
file_node_t* file_mht_node = ipf_get_mht_node(pf);
if (file_mht_node == NULL) // some error happened
return NULL;
file_node_t* new_file_data_node = NULL;
new_file_data_node = calloc(1, sizeof(*new_file_data_node));
if (!new_file_data_node) {
pf->last_error = PF_STATUS_NO_MEMORY;
return NULL;
}
new_file_data_node->type = FILE_DATA_NODE_TYPE;
new_file_data_node->new_node = true;
new_file_data_node->parent = file_mht_node;
get_node_numbers(pf->offset, NULL, &new_file_data_node->node_number, NULL,
&new_file_data_node->physical_node_number);
if (!lruc_add(pf->cache, new_file_data_node->physical_node_number, new_file_data_node)) {
free(new_file_data_node);
pf->last_error = PF_STATUS_NO_MEMORY;
return NULL;
}
return new_file_data_node;
}
static file_node_t* ipf_read_data_node(pf_context_t* pf) {
uint64_t data_node_number;
uint64_t physical_node_number;
file_node_t* file_mht_node;
pf_status_t status;
get_node_numbers(pf->offset, NULL, &data_node_number, NULL, &physical_node_number);
file_node_t* file_data_node = (file_node_t*)lruc_get(pf->cache, physical_node_number);
if (file_data_node != NULL)
return file_data_node;
// need to read the data node from the disk