blob: 6ffcf334f105ea09a746edba0bb5f010c85e164e [file] [log] [blame]
// SPDX-License-Identifier: GPL-2.0
/*
* Copyright 2018 Google LLC
*/
#include <linux/fs.h>
#include <linux/file.h>
#include <linux/types.h>
#include <linux/mutex.h>
#include <linux/mm.h>
#include <linux/falloc.h>
#include <linux/slab.h>
#include <linux/crc32.h>
#include <linux/kernel.h>
#include "format.h"
#include "data_mgmt.h"
struct backing_file_context *incfs_alloc_bfc(struct mount_info *mi,
struct file *backing_file)
{
struct backing_file_context *result = NULL;
result = kzalloc(sizeof(*result), GFP_NOFS);
if (!result)
return ERR_PTR(-ENOMEM);
result->bc_file = get_file(backing_file);
result->bc_cred = mi->mi_owner;
mutex_init(&result->bc_mutex);
return result;
}
void incfs_free_bfc(struct backing_file_context *bfc)
{
if (!bfc)
return;
if (bfc->bc_file)
fput(bfc->bc_file);
mutex_destroy(&bfc->bc_mutex);
kfree(bfc);
}
static loff_t incfs_get_end_offset(struct file *f)
{
/*
* This function assumes that file size and the end-offset
* are the same. This is not always true.
*/
return i_size_read(file_inode(f));
}
/*
* Truncate the tail of the file to the given length.
* Used to rollback partially successful multistep writes.
*/
static int truncate_backing_file(struct backing_file_context *bfc,
loff_t new_end)
{
struct inode *inode = NULL;
struct dentry *dentry = NULL;
loff_t old_end = 0;
struct iattr attr;
int result = 0;
if (!bfc)
return -EFAULT;
LOCK_REQUIRED(bfc->bc_mutex);
if (!bfc->bc_file)
return -EFAULT;
old_end = incfs_get_end_offset(bfc->bc_file);
if (old_end == new_end)
return 0;
if (old_end < new_end)
return -EINVAL;
inode = bfc->bc_file->f_inode;
dentry = bfc->bc_file->f_path.dentry;
attr.ia_size = new_end;
attr.ia_valid = ATTR_SIZE;
inode_lock(inode);
result = notify_change(&init_user_ns, dentry, &attr, NULL);
inode_unlock(inode);
return result;
}
static int write_to_bf(struct backing_file_context *bfc, const void *buf,
size_t count, loff_t pos)
{
ssize_t res = incfs_kwrite(bfc, buf, count, pos);
if (res < 0)
return res;
if (res != count)
return -EIO;
return 0;
}
static int append_zeros_no_fallocate(struct backing_file_context *bfc,
size_t file_size, size_t len)
{
u8 buffer[256] = {};
size_t i;
for (i = 0; i < len; i += sizeof(buffer)) {
int to_write = len - i > sizeof(buffer)
? sizeof(buffer) : len - i;
int err = write_to_bf(bfc, buffer, to_write, file_size + i);
if (err)
return err;
}
return 0;
}
/* Append a given number of zero bytes to the end of the backing file. */
static int append_zeros(struct backing_file_context *bfc, size_t len)
{
loff_t file_size = 0;
loff_t new_last_byte_offset = 0;
int result;
if (!bfc)
return -EFAULT;
if (len == 0)
return 0;
LOCK_REQUIRED(bfc->bc_mutex);
/*
* Allocate only one byte at the new desired end of the file.
* It will increase file size and create a zeroed area of
* a given size.
*/
file_size = incfs_get_end_offset(bfc->bc_file);
new_last_byte_offset = file_size + len - 1;
result = vfs_fallocate(bfc->bc_file, 0, new_last_byte_offset, 1);
if (result != -EOPNOTSUPP)
return result;
return append_zeros_no_fallocate(bfc, file_size, len);
}
/*
* Append a given metadata record to the backing file and update a previous
* record to add the new record the the metadata list.
*/
static int append_md_to_backing_file(struct backing_file_context *bfc,
struct incfs_md_header *record)
{
int result = 0;
loff_t record_offset;
loff_t file_pos;
__le64 new_md_offset;
size_t record_size;
if (!bfc || !record)
return -EFAULT;
if (bfc->bc_last_md_record_offset < 0)
return -EINVAL;
LOCK_REQUIRED(bfc->bc_mutex);
record_size = le16_to_cpu(record->h_record_size);
file_pos = incfs_get_end_offset(bfc->bc_file);
record->h_next_md_offset = 0;
/* Write the metadata record to the end of the backing file */
record_offset = file_pos;
new_md_offset = cpu_to_le64(record_offset);
result = write_to_bf(bfc, record, record_size, file_pos);
if (result)
return result;
/* Update next metadata offset in a previous record or a superblock. */
if (bfc->bc_last_md_record_offset) {
/*
* Find a place in the previous md record where new record's
* offset needs to be saved.
*/
file_pos = bfc->bc_last_md_record_offset +
offsetof(struct incfs_md_header, h_next_md_offset);
} else {
/*
* No metadata yet, file a place to update in the
* file_header.
*/
file_pos = offsetof(struct incfs_file_header,
fh_first_md_offset);
}
result = write_to_bf(bfc, &new_md_offset, sizeof(new_md_offset),
file_pos);
if (result)
return result;
bfc->bc_last_md_record_offset = record_offset;
return result;
}
/*
* Reserve 0-filled space for the blockmap body, and append
* incfs_blockmap metadata record pointing to it.
*/
int incfs_write_blockmap_to_backing_file(struct backing_file_context *bfc,
u32 block_count)
{
struct incfs_blockmap blockmap = {};
int result = 0;
loff_t file_end = 0;
size_t map_size = block_count * sizeof(struct incfs_blockmap_entry);
if (!bfc)
return -EFAULT;
blockmap.m_header.h_md_entry_type = INCFS_MD_BLOCK_MAP;
blockmap.m_header.h_record_size = cpu_to_le16(sizeof(blockmap));
blockmap.m_header.h_next_md_offset = cpu_to_le64(0);
blockmap.m_block_count = cpu_to_le32(block_count);
LOCK_REQUIRED(bfc->bc_mutex);
/* Reserve 0-filled space for the blockmap body in the backing file. */
file_end = incfs_get_end_offset(bfc->bc_file);
result = append_zeros(bfc, map_size);
if (result)
return result;
/* Write blockmap metadata record pointing to the body written above. */
blockmap.m_base_offset = cpu_to_le64(file_end);
result = append_md_to_backing_file(bfc, &blockmap.m_header);
if (result)
/* Error, rollback file changes */
truncate_backing_file(bfc, file_end);
return result;
}
int incfs_write_signature_to_backing_file(struct backing_file_context *bfc,
struct mem_range sig, u32 tree_size,
loff_t *tree_offset, loff_t *sig_offset)
{
struct incfs_file_signature sg = {};
int result = 0;
loff_t rollback_pos = 0;
loff_t tree_area_pos = 0;
size_t alignment = 0;
if (!bfc)
return -EFAULT;
LOCK_REQUIRED(bfc->bc_mutex);
rollback_pos = incfs_get_end_offset(bfc->bc_file);
sg.sg_header.h_md_entry_type = INCFS_MD_SIGNATURE;
sg.sg_header.h_record_size = cpu_to_le16(sizeof(sg));
sg.sg_header.h_next_md_offset = cpu_to_le64(0);
if (sig.data != NULL && sig.len > 0) {
sg.sg_sig_size = cpu_to_le32(sig.len);
sg.sg_sig_offset = cpu_to_le64(rollback_pos);
result = write_to_bf(bfc, sig.data, sig.len, rollback_pos);
if (result)
goto err;
}
tree_area_pos = incfs_get_end_offset(bfc->bc_file);
if (tree_size > 0) {
if (tree_size > 5 * INCFS_DATA_FILE_BLOCK_SIZE) {
/*
* If hash tree is big enough, it makes sense to
* align in the backing file for faster access.
*/
loff_t offset = round_up(tree_area_pos, PAGE_SIZE);
alignment = offset - tree_area_pos;
tree_area_pos = offset;
}
/*
* If root hash is not the only hash in the tree.
* reserve 0-filled space for the tree.
*/
result = append_zeros(bfc, tree_size + alignment);
if (result)
goto err;
sg.sg_hash_tree_size = cpu_to_le32(tree_size);
sg.sg_hash_tree_offset = cpu_to_le64(tree_area_pos);
}
/* Write a hash tree metadata record pointing to the hash tree above. */
result = append_md_to_backing_file(bfc, &sg.sg_header);
err:
if (result)
/* Error, rollback file changes */
truncate_backing_file(bfc, rollback_pos);
else {
if (tree_offset)
*tree_offset = tree_area_pos;
if (sig_offset)
*sig_offset = rollback_pos;
}
return result;
}
static int write_new_status_to_backing_file(struct backing_file_context *bfc,
u32 data_blocks_written,
u32 hash_blocks_written)
{
int result;
loff_t rollback_pos;
struct incfs_status is = {
.is_header = {
.h_md_entry_type = INCFS_MD_STATUS,
.h_record_size = cpu_to_le16(sizeof(is)),
},
.is_data_blocks_written = cpu_to_le32(data_blocks_written),
.is_hash_blocks_written = cpu_to_le32(hash_blocks_written),
};
LOCK_REQUIRED(bfc->bc_mutex);
rollback_pos = incfs_get_end_offset(bfc->bc_file);
result = append_md_to_backing_file(bfc, &is.is_header);
if (result)
truncate_backing_file(bfc, rollback_pos);
return result;
}
int incfs_write_status_to_backing_file(struct backing_file_context *bfc,
loff_t status_offset,
u32 data_blocks_written,
u32 hash_blocks_written)
{
struct incfs_status is;
int result;
if (!bfc)
return -EFAULT;
if (status_offset == 0)
return write_new_status_to_backing_file(bfc,
data_blocks_written, hash_blocks_written);
result = incfs_kread(bfc, &is, sizeof(is), status_offset);
if (result != sizeof(is))
return -EIO;
is.is_data_blocks_written = cpu_to_le32(data_blocks_written);
is.is_hash_blocks_written = cpu_to_le32(hash_blocks_written);
result = incfs_kwrite(bfc, &is, sizeof(is), status_offset);
if (result != sizeof(is))
return -EIO;
return 0;
}
int incfs_write_verity_signature_to_backing_file(
struct backing_file_context *bfc, struct mem_range signature,
loff_t *offset)
{
struct incfs_file_verity_signature vs = {};
int result;
loff_t pos;
/* No verity signature section is equivalent to an empty section */
if (signature.data == NULL || signature.len == 0)
return 0;
pos = incfs_get_end_offset(bfc->bc_file);
vs = (struct incfs_file_verity_signature) {
.vs_header = (struct incfs_md_header) {
.h_md_entry_type = INCFS_MD_VERITY_SIGNATURE,
.h_record_size = cpu_to_le16(sizeof(vs)),
.h_next_md_offset = cpu_to_le64(0),
},
.vs_size = cpu_to_le32(signature.len),
.vs_offset = cpu_to_le64(pos),
};
result = write_to_bf(bfc, signature.data, signature.len, pos);
if (result)
goto err;
result = append_md_to_backing_file(bfc, &vs.vs_header);
if (result)
goto err;
*offset = pos;
err:
if (result)
/* Error, rollback file changes */
truncate_backing_file(bfc, pos);
return result;
}
/*
* Write a backing file header
* It should always be called only on empty file.
* fh.fh_first_md_offset is 0 for now, but will be updated
* once first metadata record is added.
*/
int incfs_write_fh_to_backing_file(struct backing_file_context *bfc,
incfs_uuid_t *uuid, u64 file_size)
{
struct incfs_file_header fh = {};
loff_t file_pos = 0;
if (!bfc)
return -EFAULT;
fh.fh_magic = cpu_to_le64(INCFS_MAGIC_NUMBER);
fh.fh_version = cpu_to_le64(INCFS_FORMAT_CURRENT_VER);
fh.fh_header_size = cpu_to_le16(sizeof(fh));
fh.fh_first_md_offset = cpu_to_le64(0);
fh.fh_data_block_size = cpu_to_le16(INCFS_DATA_FILE_BLOCK_SIZE);
fh.fh_file_size = cpu_to_le64(file_size);
fh.fh_uuid = *uuid;
LOCK_REQUIRED(bfc->bc_mutex);
file_pos = incfs_get_end_offset(bfc->bc_file);
if (file_pos != 0)
return -EEXIST;
return write_to_bf(bfc, &fh, sizeof(fh), file_pos);
}
/*
* Write a backing file header for a mapping file
* It should always be called only on empty file.
*/
int incfs_write_mapping_fh_to_backing_file(struct backing_file_context *bfc,
incfs_uuid_t *uuid, u64 file_size, u64 offset)
{
struct incfs_file_header fh = {};
loff_t file_pos = 0;
if (!bfc)
return -EFAULT;
fh.fh_magic = cpu_to_le64(INCFS_MAGIC_NUMBER);
fh.fh_version = cpu_to_le64(INCFS_FORMAT_CURRENT_VER);
fh.fh_header_size = cpu_to_le16(sizeof(fh));
fh.fh_original_offset = cpu_to_le64(offset);
fh.fh_data_block_size = cpu_to_le16(INCFS_DATA_FILE_BLOCK_SIZE);
fh.fh_mapped_file_size = cpu_to_le64(file_size);
fh.fh_original_uuid = *uuid;
fh.fh_flags = cpu_to_le32(INCFS_FILE_MAPPED);
LOCK_REQUIRED(bfc->bc_mutex);
file_pos = incfs_get_end_offset(bfc->bc_file);
if (file_pos != 0)
return -EEXIST;
return write_to_bf(bfc, &fh, sizeof(fh), file_pos);
}
/* Write a given data block and update file's blockmap to point it. */
int incfs_write_data_block_to_backing_file(struct backing_file_context *bfc,
struct mem_range block, int block_index,
loff_t bm_base_off, u16 flags)
{
struct incfs_blockmap_entry bm_entry = {};
int result = 0;
loff_t data_offset = 0;
loff_t bm_entry_off =
bm_base_off + sizeof(struct incfs_blockmap_entry) * block_index;
if (!bfc)
return -EFAULT;
if (block.len >= (1 << 16) || block_index < 0)
return -EINVAL;
LOCK_REQUIRED(bfc->bc_mutex);
data_offset = incfs_get_end_offset(bfc->bc_file);
if (data_offset <= bm_entry_off) {
/* Blockmap entry is beyond the file's end. It is not normal. */
return -EINVAL;
}
/* Write the block data at the end of the backing file. */
result = write_to_bf(bfc, block.data, block.len, data_offset);
if (result)
return result;
/* Update the blockmap to point to the newly written data. */
bm_entry.me_data_offset_lo = cpu_to_le32((u32)data_offset);
bm_entry.me_data_offset_hi = cpu_to_le16((u16)(data_offset >> 32));
bm_entry.me_data_size = cpu_to_le16((u16)block.len);
bm_entry.me_flags = cpu_to_le16(flags);
return write_to_bf(bfc, &bm_entry, sizeof(bm_entry),
bm_entry_off);
}
int incfs_write_hash_block_to_backing_file(struct backing_file_context *bfc,
struct mem_range block,
int block_index,
loff_t hash_area_off,
loff_t bm_base_off,
loff_t file_size)
{
struct incfs_blockmap_entry bm_entry = {};
int result;
loff_t data_offset = 0;
loff_t file_end = 0;
loff_t bm_entry_off =
bm_base_off +
sizeof(struct incfs_blockmap_entry) *
(block_index + get_blocks_count_for_size(file_size));
if (!bfc)
return -EFAULT;
LOCK_REQUIRED(bfc->bc_mutex);
data_offset = hash_area_off + block_index * INCFS_DATA_FILE_BLOCK_SIZE;
file_end = incfs_get_end_offset(bfc->bc_file);
if (data_offset + block.len > file_end) {
/* Block is located beyond the file's end. It is not normal. */
return -EINVAL;
}
result = write_to_bf(bfc, block.data, block.len, data_offset);
if (result)
return result;
bm_entry.me_data_offset_lo = cpu_to_le32((u32)data_offset);
bm_entry.me_data_offset_hi = cpu_to_le16((u16)(data_offset >> 32));
bm_entry.me_data_size = cpu_to_le16(INCFS_DATA_FILE_BLOCK_SIZE);
return write_to_bf(bfc, &bm_entry, sizeof(bm_entry), bm_entry_off);
}
int incfs_read_blockmap_entry(struct backing_file_context *bfc, int block_index,
loff_t bm_base_off,
struct incfs_blockmap_entry *bm_entry)
{
int error = incfs_read_blockmap_entries(bfc, bm_entry, block_index, 1,
bm_base_off);
if (error < 0)
return error;
if (error == 0)
return -EIO;
if (error != 1)
return -EFAULT;
return 0;
}
int incfs_read_blockmap_entries(struct backing_file_context *bfc,
struct incfs_blockmap_entry *entries,
int start_index, int blocks_number,
loff_t bm_base_off)
{
loff_t bm_entry_off =
bm_base_off + sizeof(struct incfs_blockmap_entry) * start_index;
const size_t bytes_to_read = sizeof(struct incfs_blockmap_entry)
* blocks_number;
int result = 0;
if (!bfc || !entries)
return -EFAULT;
if (start_index < 0 || bm_base_off <= 0)
return -ENODATA;
result = incfs_kread(bfc, entries, bytes_to_read, bm_entry_off);
if (result < 0)
return result;
return result / sizeof(*entries);
}
int incfs_read_file_header(struct backing_file_context *bfc,
loff_t *first_md_off, incfs_uuid_t *uuid,
u64 *file_size, u32 *flags)
{
ssize_t bytes_read = 0;
struct incfs_file_header fh = {};
if (!bfc || !first_md_off)
return -EFAULT;
bytes_read = incfs_kread(bfc, &fh, sizeof(fh), 0);
if (bytes_read < 0)
return bytes_read;
if (bytes_read < sizeof(fh))
return -EBADMSG;
if (le64_to_cpu(fh.fh_magic) != INCFS_MAGIC_NUMBER)
return -EILSEQ;
if (le64_to_cpu(fh.fh_version) > INCFS_FORMAT_CURRENT_VER)
return -EILSEQ;
if (le16_to_cpu(fh.fh_data_block_size) != INCFS_DATA_FILE_BLOCK_SIZE)
return -EILSEQ;
if (le16_to_cpu(fh.fh_header_size) != sizeof(fh))
return -EILSEQ;
if (first_md_off)
*first_md_off = le64_to_cpu(fh.fh_first_md_offset);
if (uuid)
*uuid = fh.fh_uuid;
if (file_size)
*file_size = le64_to_cpu(fh.fh_file_size);
if (flags)
*flags = le32_to_cpu(fh.fh_flags);
return 0;
}
/*
* Read through metadata records from the backing file one by one
* and call provided metadata handlers.
*/
int incfs_read_next_metadata_record(struct backing_file_context *bfc,
struct metadata_handler *handler)
{
const ssize_t max_md_size = INCFS_MAX_METADATA_RECORD_SIZE;
ssize_t bytes_read = 0;
size_t md_record_size = 0;
loff_t next_record = 0;
int res = 0;
struct incfs_md_header *md_hdr = NULL;
if (!bfc || !handler)
return -EFAULT;
if (handler->md_record_offset == 0)
return -EPERM;
memset(&handler->md_buffer, 0, max_md_size);
bytes_read = incfs_kread(bfc, &handler->md_buffer, max_md_size,
handler->md_record_offset);
if (bytes_read < 0)
return bytes_read;
if (bytes_read < sizeof(*md_hdr))
return -EBADMSG;
md_hdr = &handler->md_buffer.md_header;
next_record = le64_to_cpu(md_hdr->h_next_md_offset);
md_record_size = le16_to_cpu(md_hdr->h_record_size);
if (md_record_size > max_md_size) {
pr_warn("incfs: The record is too large. Size: %zu",
md_record_size);
return -EBADMSG;
}
if (bytes_read < md_record_size) {
pr_warn("incfs: The record hasn't been fully read.");
return -EBADMSG;
}
if (next_record <= handler->md_record_offset && next_record != 0) {
pr_warn("incfs: Next record (%lld) points back in file.",
next_record);
return -EBADMSG;
}
switch (md_hdr->h_md_entry_type) {
case INCFS_MD_NONE:
break;
case INCFS_MD_BLOCK_MAP:
if (handler->handle_blockmap)
res = handler->handle_blockmap(
&handler->md_buffer.blockmap, handler);
break;
case INCFS_MD_FILE_ATTR:
/*
* File attrs no longer supported, ignore section for
* compatibility
*/
break;
case INCFS_MD_SIGNATURE:
if (handler->handle_signature)
res = handler->handle_signature(
&handler->md_buffer.signature, handler);
break;
case INCFS_MD_STATUS:
if (handler->handle_status)
res = handler->handle_status(
&handler->md_buffer.status, handler);
break;
case INCFS_MD_VERITY_SIGNATURE:
if (handler->handle_verity_signature)
res = handler->handle_verity_signature(
&handler->md_buffer.verity_signature, handler);
break;
default:
res = -ENOTSUPP;
break;
}
if (!res) {
if (next_record == 0) {
/*
* Zero offset for the next record means that the last
* metadata record has just been processed.
*/
bfc->bc_last_md_record_offset =
handler->md_record_offset;
}
handler->md_prev_record_offset = handler->md_record_offset;
handler->md_record_offset = next_record;
}
return res;
}
ssize_t incfs_kread(struct backing_file_context *bfc, void *buf, size_t size,
loff_t pos)
{
const struct cred *old_cred = override_creds(bfc->bc_cred);
int ret = kernel_read(bfc->bc_file, buf, size, &pos);
revert_creds(old_cred);
return ret;
}
ssize_t incfs_kwrite(struct backing_file_context *bfc, const void *buf,
size_t size, loff_t pos)
{
const struct cred *old_cred = override_creds(bfc->bc_cred);
int ret = kernel_write(bfc->bc_file, buf, size, &pos);
revert_creds(old_cred);
return ret;
}