mirror of https://github.com/Qortal/Brooklyn
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
294 lines
8.1 KiB
294 lines
8.1 KiB
// SPDX-License-Identifier: GPL-2.0 |
|
/* |
|
* fs/f2fs/verity.c: fs-verity support for f2fs |
|
* |
|
* Copyright 2019 Google LLC |
|
*/ |
|
|
|
/* |
|
* Implementation of fsverity_operations for f2fs. |
|
* |
|
* Like ext4, f2fs stores the verity metadata (Merkle tree and |
|
* fsverity_descriptor) past the end of the file, starting at the first 64K |
|
* boundary beyond i_size. This approach works because (a) verity files are |
|
* readonly, and (b) pages fully beyond i_size aren't visible to userspace but |
|
* can be read/written internally by f2fs with only some relatively small |
|
* changes to f2fs. Extended attributes cannot be used because (a) f2fs limits |
|
* the total size of an inode's xattr entries to 4096 bytes, which wouldn't be |
|
* enough for even a single Merkle tree block, and (b) f2fs encryption doesn't |
|
* encrypt xattrs, yet the verity metadata *must* be encrypted when the file is |
|
* because it contains hashes of the plaintext data. |
|
* |
|
* Using a 64K boundary rather than a 4K one keeps things ready for |
|
* architectures with 64K pages, and it doesn't necessarily waste space on-disk |
|
* since there can be a hole between i_size and the start of the Merkle tree. |
|
*/ |
|
|
|
#include <linux/f2fs_fs.h> |
|
|
|
#include "f2fs.h" |
|
#include "xattr.h" |
|
|
|
#define F2FS_VERIFY_VER (1) |
|
|
|
static inline loff_t f2fs_verity_metadata_pos(const struct inode *inode) |
|
{ |
|
return round_up(inode->i_size, 65536); |
|
} |
|
|
|
/* |
|
* Read some verity metadata from the inode. __vfs_read() can't be used because |
|
* we need to read beyond i_size. |
|
*/ |
|
static int pagecache_read(struct inode *inode, void *buf, size_t count, |
|
loff_t pos) |
|
{ |
|
while (count) { |
|
size_t n = min_t(size_t, count, |
|
PAGE_SIZE - offset_in_page(pos)); |
|
struct page *page; |
|
void *addr; |
|
|
|
page = read_mapping_page(inode->i_mapping, pos >> PAGE_SHIFT, |
|
NULL); |
|
if (IS_ERR(page)) |
|
return PTR_ERR(page); |
|
|
|
addr = kmap_atomic(page); |
|
memcpy(buf, addr + offset_in_page(pos), n); |
|
kunmap_atomic(addr); |
|
|
|
put_page(page); |
|
|
|
buf += n; |
|
pos += n; |
|
count -= n; |
|
} |
|
return 0; |
|
} |
|
|
|
/* |
|
* Write some verity metadata to the inode for FS_IOC_ENABLE_VERITY. |
|
* kernel_write() can't be used because the file descriptor is readonly. |
|
*/ |
|
static int pagecache_write(struct inode *inode, const void *buf, size_t count, |
|
loff_t pos) |
|
{ |
|
if (pos + count > inode->i_sb->s_maxbytes) |
|
return -EFBIG; |
|
|
|
while (count) { |
|
size_t n = min_t(size_t, count, |
|
PAGE_SIZE - offset_in_page(pos)); |
|
struct page *page; |
|
void *fsdata; |
|
void *addr; |
|
int res; |
|
|
|
res = pagecache_write_begin(NULL, inode->i_mapping, pos, n, 0, |
|
&page, &fsdata); |
|
if (res) |
|
return res; |
|
|
|
addr = kmap_atomic(page); |
|
memcpy(addr + offset_in_page(pos), buf, n); |
|
kunmap_atomic(addr); |
|
|
|
res = pagecache_write_end(NULL, inode->i_mapping, pos, n, n, |
|
page, fsdata); |
|
if (res < 0) |
|
return res; |
|
if (res != n) |
|
return -EIO; |
|
|
|
buf += n; |
|
pos += n; |
|
count -= n; |
|
} |
|
return 0; |
|
} |
|
|
|
/* |
|
* Format of f2fs verity xattr. This points to the location of the verity |
|
* descriptor within the file data rather than containing it directly because |
|
* the verity descriptor *must* be encrypted when f2fs encryption is used. But, |
|
* f2fs encryption does not encrypt xattrs. |
|
*/ |
|
struct fsverity_descriptor_location { |
|
__le32 version; |
|
__le32 size; |
|
__le64 pos; |
|
}; |
|
|
|
static int f2fs_begin_enable_verity(struct file *filp) |
|
{ |
|
struct inode *inode = file_inode(filp); |
|
int err; |
|
|
|
if (f2fs_verity_in_progress(inode)) |
|
return -EBUSY; |
|
|
|
if (f2fs_is_atomic_file(inode) || f2fs_is_volatile_file(inode)) |
|
return -EOPNOTSUPP; |
|
|
|
/* |
|
* Since the file was opened readonly, we have to initialize the quotas |
|
* here and not rely on ->open() doing it. This must be done before |
|
* evicting the inline data. |
|
*/ |
|
err = dquot_initialize(inode); |
|
if (err) |
|
return err; |
|
|
|
err = f2fs_convert_inline_inode(inode); |
|
if (err) |
|
return err; |
|
|
|
set_inode_flag(inode, FI_VERITY_IN_PROGRESS); |
|
return 0; |
|
} |
|
|
|
static int f2fs_end_enable_verity(struct file *filp, const void *desc, |
|
size_t desc_size, u64 merkle_tree_size) |
|
{ |
|
struct inode *inode = file_inode(filp); |
|
struct f2fs_sb_info *sbi = F2FS_I_SB(inode); |
|
u64 desc_pos = f2fs_verity_metadata_pos(inode) + merkle_tree_size; |
|
struct fsverity_descriptor_location dloc = { |
|
.version = cpu_to_le32(F2FS_VERIFY_VER), |
|
.size = cpu_to_le32(desc_size), |
|
.pos = cpu_to_le64(desc_pos), |
|
}; |
|
int err = 0, err2 = 0; |
|
|
|
/* |
|
* If an error already occurred (which fs/verity/ signals by passing |
|
* desc == NULL), then only clean-up is needed. |
|
*/ |
|
if (desc == NULL) |
|
goto cleanup; |
|
|
|
/* Append the verity descriptor. */ |
|
err = pagecache_write(inode, desc, desc_size, desc_pos); |
|
if (err) |
|
goto cleanup; |
|
|
|
/* |
|
* Write all pages (both data and verity metadata). Note that this must |
|
* happen before clearing FI_VERITY_IN_PROGRESS; otherwise pages beyond |
|
* i_size won't be written properly. For crash consistency, this also |
|
* must happen before the verity inode flag gets persisted. |
|
*/ |
|
err = filemap_write_and_wait(inode->i_mapping); |
|
if (err) |
|
goto cleanup; |
|
|
|
/* Set the verity xattr. */ |
|
err = f2fs_setxattr(inode, F2FS_XATTR_INDEX_VERITY, |
|
F2FS_XATTR_NAME_VERITY, &dloc, sizeof(dloc), |
|
NULL, XATTR_CREATE); |
|
if (err) |
|
goto cleanup; |
|
|
|
/* Finally, set the verity inode flag. */ |
|
file_set_verity(inode); |
|
f2fs_set_inode_flags(inode); |
|
f2fs_mark_inode_dirty_sync(inode, true); |
|
|
|
clear_inode_flag(inode, FI_VERITY_IN_PROGRESS); |
|
return 0; |
|
|
|
cleanup: |
|
/* |
|
* Verity failed to be enabled, so clean up by truncating any verity |
|
* metadata that was written beyond i_size (both from cache and from |
|
* disk) and clearing FI_VERITY_IN_PROGRESS. |
|
* |
|
* Taking i_gc_rwsem[WRITE] is needed to stop f2fs garbage collection |
|
* from re-instantiating cached pages we are truncating (since unlike |
|
* normal file accesses, garbage collection isn't limited by i_size). |
|
*/ |
|
down_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]); |
|
truncate_inode_pages(inode->i_mapping, inode->i_size); |
|
err2 = f2fs_truncate(inode); |
|
if (err2) { |
|
f2fs_err(sbi, "Truncating verity metadata failed (errno=%d)", |
|
err2); |
|
set_sbi_flag(sbi, SBI_NEED_FSCK); |
|
} |
|
up_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]); |
|
clear_inode_flag(inode, FI_VERITY_IN_PROGRESS); |
|
return err ?: err2; |
|
} |
|
|
|
static int f2fs_get_verity_descriptor(struct inode *inode, void *buf, |
|
size_t buf_size) |
|
{ |
|
struct fsverity_descriptor_location dloc; |
|
int res; |
|
u32 size; |
|
u64 pos; |
|
|
|
/* Get the descriptor location */ |
|
res = f2fs_getxattr(inode, F2FS_XATTR_INDEX_VERITY, |
|
F2FS_XATTR_NAME_VERITY, &dloc, sizeof(dloc), NULL); |
|
if (res < 0 && res != -ERANGE) |
|
return res; |
|
if (res != sizeof(dloc) || dloc.version != cpu_to_le32(F2FS_VERIFY_VER)) { |
|
f2fs_warn(F2FS_I_SB(inode), "unknown verity xattr format"); |
|
return -EINVAL; |
|
} |
|
size = le32_to_cpu(dloc.size); |
|
pos = le64_to_cpu(dloc.pos); |
|
|
|
/* Get the descriptor */ |
|
if (pos + size < pos || pos + size > inode->i_sb->s_maxbytes || |
|
pos < f2fs_verity_metadata_pos(inode) || size > INT_MAX) { |
|
f2fs_warn(F2FS_I_SB(inode), "invalid verity xattr"); |
|
return -EFSCORRUPTED; |
|
} |
|
if (buf_size) { |
|
if (size > buf_size) |
|
return -ERANGE; |
|
res = pagecache_read(inode, buf, size, pos); |
|
if (res) |
|
return res; |
|
} |
|
return size; |
|
} |
|
|
|
static struct page *f2fs_read_merkle_tree_page(struct inode *inode, |
|
pgoff_t index, |
|
unsigned long num_ra_pages) |
|
{ |
|
DEFINE_READAHEAD(ractl, NULL, NULL, inode->i_mapping, index); |
|
struct page *page; |
|
|
|
index += f2fs_verity_metadata_pos(inode) >> PAGE_SHIFT; |
|
|
|
page = find_get_page_flags(inode->i_mapping, index, FGP_ACCESSED); |
|
if (!page || !PageUptodate(page)) { |
|
if (page) |
|
put_page(page); |
|
else if (num_ra_pages > 1) |
|
page_cache_ra_unbounded(&ractl, num_ra_pages, 0); |
|
page = read_mapping_page(inode->i_mapping, index, NULL); |
|
} |
|
return page; |
|
} |
|
|
|
static int f2fs_write_merkle_tree_block(struct inode *inode, const void *buf, |
|
u64 index, int log_blocksize) |
|
{ |
|
loff_t pos = f2fs_verity_metadata_pos(inode) + (index << log_blocksize); |
|
|
|
return pagecache_write(inode, buf, 1 << log_blocksize, pos); |
|
} |
|
|
|
const struct fsverity_operations f2fs_verityops = { |
|
.begin_enable_verity = f2fs_begin_enable_verity, |
|
.end_enable_verity = f2fs_end_enable_verity, |
|
.get_verity_descriptor = f2fs_get_verity_descriptor, |
|
.read_merkle_tree_page = f2fs_read_merkle_tree_page, |
|
.write_merkle_tree_block = f2fs_write_merkle_tree_block, |
|
};
|
|
|