It missed to hold i_gc_rwsem and i_map_sem around f2fs_truncate()
in f2fs_file_write_iter() to avoid racing with background GC and
mmap, fix it.
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Once we introduced checkpoint_merge, we've seen some contention w/o the option.
In order to avoid it, let's set it by default.
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
In the cache writing process, if it is an atomic file, increase the page
count of F2FS_WB_CP_DATA, otherwise increase the page count of
F2FS_WB_DATA.
When you step into the hook branch due to insufficient memory in
f2fs_write_begin, f2fs_drop_inmem_pages_all will be called to traverse
all atomic inodes and clear the FI_ATOMIC_FILE mark of all atomic files.
In f2fs_drop_inmem_pages，first acquire the inmem_lock , revoke all the
inmem_pages, and then clear the FI_ATOMIC_FILE mark. Before this mark is
cleared, other threads may hold inmem_lock to add inmem_pages to the inode
that has just been emptied inmem_pages, and increase the page count of
F2FS_WB_CP_DATA.
When the IO returns, it is found that the FI_ATOMIC_FILE flag is cleared
by f2fs_drop_inmem_pages_all, and f2fs_is_atomic_file returns false,which
causes the page count of F2FS_WB_DATA to be decremented. The page count of
F2FS_WB_CP_DATA cannot be cleared. Finally, hungtask is triggered in
f2fs_wait_on_all_pages because get_pages will never return zero.
process A: process B:
f2fs_drop_inmem_pages_all
->f2fs_drop_inmem_pages of inode#1
->mutex_lock(&fi->inmem_lock)
->__revoke_inmem_pages of inode#1 f2fs_ioc_commit_atomic_write
->mutex_unlock(&fi->inmem_lock) ->f2fs_commit_inmem_pages of inode#1
->mutex_lock(&fi->inmem_lock)
->__f2fs_commit_inmem_pages
->f2fs_do_write_data_page
->f2fs_outplace_write_data
->do_write_page
->f2fs_submit_page_write
->inc_page_count(sbi, F2FS_WB_CP_DATA )
->mutex_unlock(&fi->inmem_lock)
->spin_lock(&sbi->inode_lock[ATOMIC_FILE]);
->clear_inode_flag(inode, FI_ATOMIC_FILE)
->spin_unlock(&sbi->inode_lock[ATOMIC_FILE])
f2fs_write_end_io
->dec_page_count(sbi, F2FS_WB_DATA );
We can fix the problem by putting the action of clearing the FI_ATOMIC_FILE
mark into the inmem_lock lock. This operation can ensure that no one will
submit the inmem pages before the FI_ATOMIC_FILE mark is cleared, so that
there will be no atomic writes waiting for writeback.
Fixes: 57864ae5ce ("f2fs: limit # of inmemory pages")
Signed-off-by: Yi Zhuang <zhuangyi1@huawei.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
When we mount an unclean f2fs image in a readonly block device, let's
make mount() succeed only when there is no recoverable data in that
image, otherwise after mount(), file fsyned won't be recovered as user
expected.
Fixes: 938a184265 ("f2fs: give a warning only for readonly partition")
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
In this patch, we will add two new mount options: "gc_merge" and
"nogc_merge", when background_gc is on, "gc_merge" option can be
set to let background GC thread to handle foreground GC requests,
it can eliminate the sluggish issue caused by slow foreground GC
operation when GC is triggered from a process with limited I/O
and CPU resources.
Original idea is from Xiang.
Signed-off-by: Gao Xiang <xiang@kernel.org>
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
In order to avoid race with f2fs_do_replace_block().
Fixes: f5a53edcf0 ("f2fs: support aligned pinned file")
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
If the alloc_type of the original curseg is LFS,
when we change_curseg and then do recover curseg,
the alloc_type becomes SSR.
Signed-off-by: Wang Xiaojun <wangxiaojun11@huawei.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
With the default DPOLICY_BG discard thread is ioaware, which prevents
the discard thread from issuing the discard commands. On low RAM setups,
it is observed that these discard commands in the cache are consuming
high memory. This patch aims to relax the memory pressure on the system
due to f2fs pending discard cmds by changing the policy to DPOLICY_FORCE
based on the nm_i->ram_thresh configured.
Signed-off-by: Sahitya Tummala <stummala@codeaurora.org>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
In CP disabling mode, there are two issues when using LFS or SSR | AT_SSR
mode to select victim:
1. LFS is set to find source section during GC, the victim should have
no checkpointed data, since after GC, section could not be set free for
reuse.
Previously, we only check valid chpt blocks in current segment rather
than section, fix it.
2. SSR | AT_SSR are set to find target segment for writes which can be
fully filled by checkpointed and newly written blocks, we should never
select such segment, otherwise it can cause panic or data corruption
during allocation, potential case is described as below:
a) target segment has 128 ckpt valid blocks
b) GC migrates 'n' (n < 512) valid blocks to other segment (segment is
still in dirty list)
c) GC migrates '512 - n' blocks to target segment (segment has 'n'
cp_vblocks and '512 - n' vblocks)
d) If GC selects target segment via {AT,}SSR allocator, however there
is no free space in targe segment.
Fixes: 4354994f09 ("f2fs: checkpoint disabling")
Fixes: 093749e296 ("f2fs: support age threshold based garbage collection")
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
In the case of expanding pinned file, map.m_lblk and map.m_len
will update in each round of section allocation, so in error
path, last i_size will be calculated with wrong m_lblk and m_len,
fix it.
Fixes: f5a53edcf0 ("f2fs: support aligned pinned file")
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
In error path of f2fs_remount(), it missed to restart/stop kernel thread
or enable/disable checkpoint, then mount option status may not be
consistent with real condition of filesystem, so let's reorder remount
flow a bit as below and do recovery correctly in error path:
1) handle gc thread
2) handle ckpt thread
3) handle flush thread
4) handle checkpoint disabling
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
butt3rflyh4ck <butterflyhuangxx@gmail.com> reported a bug found by
syzkaller fuzzer with custom modifications in 5.12.0-rc3+ [1]:
dump_stack+0xfa/0x151 lib/dump_stack.c:120
print_address_description.constprop.0.cold+0x82/0x32c mm/kasan/report.c:232
__kasan_report mm/kasan/report.c:399 [inline]
kasan_report.cold+0x7c/0xd8 mm/kasan/report.c:416
f2fs_test_bit fs/f2fs/f2fs.h:2572 [inline]
current_nat_addr fs/f2fs/node.h:213 [inline]
get_next_nat_page fs/f2fs/node.c:123 [inline]
__flush_nat_entry_set fs/f2fs/node.c:2888 [inline]
f2fs_flush_nat_entries+0x258e/0x2960 fs/f2fs/node.c:2991
f2fs_write_checkpoint+0x1372/0x6a70 fs/f2fs/checkpoint.c:1640
f2fs_issue_checkpoint+0x149/0x410 fs/f2fs/checkpoint.c:1807
f2fs_sync_fs+0x20f/0x420 fs/f2fs/super.c:1454
__sync_filesystem fs/sync.c:39 [inline]
sync_filesystem fs/sync.c:67 [inline]
sync_filesystem+0x1b5/0x260 fs/sync.c:48
generic_shutdown_super+0x70/0x370 fs/super.c:448
kill_block_super+0x97/0xf0 fs/super.c:1394
The root cause is, if nat entry in checkpoint journal area is corrupted,
e.g. nid of journalled nat entry exceeds max nid value, during checkpoint,
once it tries to flush nat journal to NAT area, get_next_nat_page() may
access out-of-bounds memory on nat_bitmap due to it uses wrong nid value
as bitmap offset.
[1] https://lore.kernel.org/lkml/CAFcO6XOMWdr8pObek6eN6-fs58KG9doRFadgJj-FnF-1x43s2g@mail.gmail.com/T/#u
Reported-and-tested-by: butt3rflyh4ck <butterflyhuangxx@gmail.com>
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
In readonly mountpoint, there should be no write IOs include checkpoint
IO, so that it's not needed to create kernel checkpoint thread.
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
AT_SSR mode is introduced by age threshold based GC for better
hot/cold data seperation and avoiding free segment cost. However,
LFS write mode is preferred in the scenario of foreground or high
urgent GC, which should be finished ASAP. Let's only use AT_SSR
in background GC and not high urgent GC modes.
Signed-off-by: Weichao Guo <guoweichao@oppo.com>
Signed-off-by: Huang Jianan <huangjianan@oppo.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
I've added new sysfs nodes to show runtime compression stat since mount.
compr_written_block - show the block count written after compression
compr_saved_block - show the saved block count with compression
compr_new_inode - show the count of inode newly enabled for compression
Signed-off-by: Daeho Jeong <daehojeong@google.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Now, fallocate() on a pinned file only allocates blocks which aligns
to segment rather than section, so GC may try to migrate pinned file's
block, and after several times of failure, pinned file's block could
be migrated to other place, however user won't be aware of such
condition, and then old obsolete block address may be readed/written
incorrectly.
To avoid such condition, let's try to allocate pinned file's blocks
with section alignment.
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This is useful when checking conditions during checkpoint=disable in Android.
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
f2fs didn't properly clean up if verity failed to be enabled on a file:
- It left verity metadata (pages past EOF) in the page cache, which
would be exposed to userspace if the file was later extended.
- It didn't truncate the verity metadata at all (either from cache or
from disk) if an error occurred while setting the verity bit.
Fix these bugs by adding a call to truncate_inode_pages() and ensuring
that we truncate the verity metadata (both from cache and from disk) in
all error paths. Also rework the code to cleanly separate the success
path from the error paths, which makes it much easier to understand.
Finally, log a message if f2fs_truncate() fails, since it might
otherwise fail silently.
Reported-by: Yunlei He <heyunlei@hihonor.com>
Fixes: 95ae251fe8 ("f2fs: add fs-verity support")
Cc: <stable@vger.kernel.org> # v5.4+
Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
The uninitialized variable dn.node_changed does not get set when a
call to f2fs_get_node_page fails. This uninitialized value gets used
in the call to f2fs_balance_fs() that may or not may not balances
dirty node and dentry pages depending on the uninitialized state of
the variable. Fix this by only calling f2fs_balance_fs if err is
not set.
Thanks to Jaegeuk Kim for suggesting an appropriate fix.
Addresses-Coverity: ("Uninitialized scalar variable")
Fixes: 2a34076070 ("f2fs: call f2fs_balance_fs only when node was changed")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
- file_clear_encrypt() was never be used, remove it.
- In addition, relocating macros for cleanup.
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
If the swapfile isn't created by pin and fallocate, it can't be
guaranteed section-aligned, so it may be selected by f2fs gc. When
gc_pin_file_threshold is reached, the address of swapfile may change,
but won't be synchronized to swap_extent, so swap will write to wrong
address, which will cause data corruption.
Signed-off-by: Huang Jianan <huangjianan@oppo.com>
Signed-off-by: Guo Weichao <guoweichao@oppo.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Because page_no < sis->max guarantees that the while loop break out
normally, the wrong check contidion here doesn't cause a problem.
Signed-off-by: Huang Jianan <huangjianan@oppo.com>
Signed-off-by: Guo Weichao <guoweichao@oppo.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Now swapfile in f2fs directly submit IO to blockdev according to
swapfile extents reported by f2fs when swapon, therefore there is
no need to check IS_SWAPFILE when exec filesystem operation.
Signed-off-by: Huang Jianan <huangjianan@oppo.com>
Signed-off-by: Guo Weichao <guoweichao@oppo.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
There is a regular need in the kernel to provide a way to declare having
a dynamically sized set of trailing elements in a structure. Kernel code
should always use “flexible array members”[1] for these cases. The older
style of one-element or zero-length arrays should no longer be used[2].
Refactor the code according to the use of a flexible-array member in
struct f2fs_checkpoint, instead of a one-element arrays.
Notice that a temporary pointer to void '*tmp_ptr' was used in order to
fix the following errors when using a flexible array instead of a one
element array in struct f2fs_checkpoint:
CC [M] fs/f2fs/dir.o
In file included from fs/f2fs/dir.c:13:
fs/f2fs/f2fs.h: In function ‘__bitmap_ptr’:
fs/f2fs/f2fs.h:2227:40: error: invalid use of flexible array member
2227 | return &ckpt->sit_nat_version_bitmap + offset + sizeof(__le32);
| ^
fs/f2fs/f2fs.h:2227:49: error: invalid use of flexible array member
2227 | return &ckpt->sit_nat_version_bitmap + offset + sizeof(__le32);
| ^
fs/f2fs/f2fs.h:2238:40: error: invalid use of flexible array member
2238 | return &ckpt->sit_nat_version_bitmap + offset;
| ^
make[2]: *** [scripts/Makefile.build:287: fs/f2fs/dir.o] Error 1
make[1]: *** [scripts/Makefile.build:530: fs/f2fs] Error 2
make: *** [Makefile:1819: fs] Error 2
[1] https://en.wikipedia.org/wiki/Flexible_array_member
[2] https://www.kernel.org/doc/html/v5.9/process/deprecated.html#zero-length-and-one-element-arrays
Link: https://github.com/KSPP/linux/issues/79
Build-tested-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/lkml/603647e4.DeEFbl4eqljuwAUe%25lkp@intel.com/
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
If F2FS_FS is modular, enabling the compressions options
F2FS_FS_{LZ4,LZ4HZ,LZO,LZORLE,ZSTD} will make the (de)compression
algorithms {LZ4,LZ4HC,LZO,ZSTD}_{,DE}COMPRESS builtin instead of
modular, as the former depend on an intermediate boolean
F2FS_FS_COMPRESSION, which in-turn depends on tristate F2FS_FS.
Indeed, if a boolean symbol A depends directly on a tristate symbol B
and selects another tristate symbol C:
tristate B
tristate C
bool A
depends on B
select C
and B is modular, then C will also be modular.
However, if there is an intermediate boolean D in the dependency chain
between A and B:
tristate B
tristate C
bool D
depends on B
bool A
depends on D
select C
then the modular state won't propagate from B to C, and C will be
builtin instead of modular.
As modular dependency propagation through intermediate symbols is
obscure, fix this in a robust way by moving the selection of tristate
(de)compression algorithms from the boolean compression options to the
tristate main F2FS_FS option.
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Reviewed-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
In trim thread, let's add a condition to check discard command number
before traversing discard pending list, it can avoid unneeded traversing
if there is no discard command.
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Add more detailed comments for explicit memory barrier used by
f2fs, in order to enhance code readability.
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
FORCE_FG_GC was introduced by commit 6aefd93b01 ("f2fs: introduce
background_gc=sync mount option"), but never be used, remove it.
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
LKP reports:
fs/f2fs/super.c:1516:20: warning: unused function 'f2fs_show_compress_options' [-Wunused-function]
static inline void f2fs_show_compress_options(struct seq_file *seq,
Fix this issue by covering f2fs_show_compress_options() with
CONFIG_F2FS_FS_COMPRESSION macro.
Fixes: 4c8ff7095b ("f2fs: support data compression")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
f2fs_resize_fs() hangs in below callstack with testcase:
- mkfs 16GB image & mount image
- dd 8GB fileA
- dd 8GB fileB
- sync
- rm fileA
- sync
- resize filesystem to 8GB
kernel BUG at segment.c:2484!
Call Trace:
allocate_segment_by_default+0x92/0xf0 [f2fs]
f2fs_allocate_data_block+0x44b/0x7e0 [f2fs]
do_write_page+0x5a/0x110 [f2fs]
f2fs_outplace_write_data+0x55/0x100 [f2fs]
f2fs_do_write_data_page+0x392/0x850 [f2fs]
move_data_page+0x233/0x320 [f2fs]
do_garbage_collect+0x14d9/0x1660 [f2fs]
free_segment_range+0x1f7/0x310 [f2fs]
f2fs_resize_fs+0x118/0x330 [f2fs]
__f2fs_ioctl+0x487/0x3680 [f2fs]
__x64_sys_ioctl+0x8e/0xd0
do_syscall_64+0x33/0x80
entry_SYSCALL_64_after_hwframe+0x44/0xa9
The root cause is we forgot to check that whether we have enough space
in resized filesystem to store all valid blocks in before-resizing
filesystem, then allocator will run out-of-space during block migration
in free_segment_range().
Fixes: b4b10061ef ("f2fs: refactor resize_fs to avoid meta updates in progress")
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
F2FS_IOC_FLUSH_DEVICE/F2FS_IOC_RESIZE_FS needs to migrate all blocks of
target segment to other place, no matter the segment has partially or fully
valid blocks.
However, after commit 803e74be04 ("f2fs: stop GC when the victim becomes
fully valid"), we may skip migration due to target segment is fully valid,
result in failing the ioctl interface, fix this.
Fixes: 803e74be04 ("f2fs: stop GC when the victim becomes fully valid")
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Add support for FS_VERITY_METADATA_TYPE_SIGNATURE to
FS_IOC_READ_VERITY_METADATA. This allows a userspace server program to
retrieve the built-in signature (if present) of a verity file for
serving to a client which implements fs-verity compatible verification.
See the patch which introduced FS_IOC_READ_VERITY_METADATA for more
details.
The ability for userspace to read the built-in signatures is also useful
because it allows a system that is using the in-kernel signature
verification to migrate to userspace signature verification.
This has been tested using a new xfstest which calls this ioctl via a
new subcommand for the 'fsverity' program from fsverity-utils.
Link: https://lore.kernel.org/r/20210115181819.34732-7-ebiggers@kernel.org
Reviewed-by: Victor Hsieh <victorhsieh@google.com>
Reviewed-by: Jaegeuk Kim <jaegeuk@kernel.org>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Add support for FS_VERITY_METADATA_TYPE_DESCRIPTOR to
FS_IOC_READ_VERITY_METADATA. This allows a userspace server program to
retrieve the fs-verity descriptor of a file for serving to a client
which implements fs-verity compatible verification. See the patch which
introduced FS_IOC_READ_VERITY_METADATA for more details.
"fs-verity descriptor" here means only the part that userspace cares
about because it is hashed to produce the file digest. It doesn't
include the signature which ext4 and f2fs append to the
fsverity_descriptor struct when storing it on-disk, since that way of
storing the signature is an implementation detail. The next patch adds
a separate metadata_type value for retrieving the signature separately.
This has been tested using a new xfstest which calls this ioctl via a
new subcommand for the 'fsverity' program from fsverity-utils.
Link: https://lore.kernel.org/r/20210115181819.34732-6-ebiggers@kernel.org
Reviewed-by: Victor Hsieh <victorhsieh@google.com>
Reviewed-by: Jaegeuk Kim <jaegeuk@kernel.org>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Add support for FS_VERITY_METADATA_TYPE_MERKLE_TREE to
FS_IOC_READ_VERITY_METADATA. This allows a userspace server program to
retrieve the Merkle tree of a verity file for serving to a client which
implements fs-verity compatible verification. See the patch which
introduced FS_IOC_READ_VERITY_METADATA for more details.
This has been tested using a new xfstest which calls this ioctl via a
new subcommand for the 'fsverity' program from fsverity-utils.
Link: https://lore.kernel.org/r/20210115181819.34732-5-ebiggers@kernel.org
Reviewed-by: Victor Hsieh <victorhsieh@google.com>
Reviewed-by: Jaegeuk Kim <jaegeuk@kernel.org>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Add an ioctl FS_IOC_READ_VERITY_METADATA which will allow reading verity
metadata from a file that has fs-verity enabled, including:
- The Merkle tree
- The fsverity_descriptor (not including the signature if present)
- The built-in signature, if present
This ioctl has similar semantics to pread(). It is passed the type of
metadata to read (one of the above three), and a buffer, offset, and
size. It returns the number of bytes read or an error.
Separate patches will add support for each of the above metadata types.
This patch just adds the ioctl itself.
This ioctl doesn't make any assumption about where the metadata is
stored on-disk. It does assume the metadata is in a stable format, but
that's basically already the case:
- The Merkle tree and fsverity_descriptor are defined by how fs-verity
file digests are computed; see the "File digest computation" section
of Documentation/filesystems/fsverity.rst. Technically, the way in
which the levels of the tree are ordered relative to each other wasn't
previously specified, but it's logical to put the root level first.
- The built-in signature is the value passed to FS_IOC_ENABLE_VERITY.
This ioctl is useful because it allows writing a server program that
takes a verity file and serves it to a client program, such that the
client can do its own fs-verity compatible verification of the file.
This only makes sense if the client doesn't trust the server and if the
server needs to provide the storage for the client.
More concretely, there is interest in using this ability in Android to
export APK files (which are protected by fs-verity) to "protected VMs".
This would use Protected KVM (https://lwn.net/Articles/836693), which
provides an isolated execution environment without having to trust the
traditional "host". A "guest" VM can boot from a signed image and
perform specific tasks in a minimum trusted environment using files that
have fs-verity enabled on the host, without trusting the host or
requiring that the guest has its own trusted storage.
Technically, it would be possible to duplicate the metadata and store it
in separate files for serving. However, that would be less efficient
and would require extra care in userspace to maintain file consistency.
In addition to the above, the ability to read the built-in signatures is
useful because it allows a system that is using the in-kernel signature
verification to migrate to userspace signature verification.
Link: https://lore.kernel.org/r/20210115181819.34732-4-ebiggers@kernel.org
Reviewed-by: Victor Hsieh <victorhsieh@google.com>
Acked-by: Jaegeuk Kim <jaegeuk@kernel.org>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
The FS_IOC_READ_VERITY_METADATA ioctl will need to return the fs-verity
descriptor (and signature) to userspace.
There are a few ways we could implement this:
- Save a copy of the descriptor (and signature) in the fsverity_info
struct that hangs off of the in-memory inode. However, this would
waste memory since most of the time it wouldn't be needed.
- Regenerate the descriptor from the merkle_tree_params in the
fsverity_info. However, this wouldn't work for the signature, nor for
the salt which the merkle_tree_params only contains indirectly as part
of the 'hashstate'. It would also be error-prone.
- Just get them from the filesystem again. The disadvantage is that in
general we can't trust that they haven't been maliciously changed
since the file has opened. However, the use cases for
FS_IOC_READ_VERITY_METADATA don't require that it verifies the chain
of trust. So this is okay as long as we do some basic validation.
In preparation for implementing the third option, factor out a helper
function fsverity_get_descriptor() which gets the descriptor (and
appended signature) from the filesystem and does some basic validation.
As part of this, start checking the sig_size field for overflow.
Currently fsverity_verify_signature() does this. But the new ioctl will
need this too, so do it earlier.
Link: https://lore.kernel.org/r/20210115181819.34732-2-ebiggers@kernel.org
Reviewed-by: Victor Hsieh <victorhsieh@google.com>
Reviewed-by: Jaegeuk Kim <jaegeuk@kernel.org>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Store the frozen superblock in struct block_device to avoid the awkward
interface that can return a sb only used a cookie, an ERR_PTR or NULL.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Chao Yu <yuchao0@huawei.com> [f2fs]
Signed-off-by: Jens Axboe <axboe@kernel.dk>
bd_part is never NULL for a block device in use by a file system, so
remove the checks.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Let's allow mounting readonly partition. We're able to recovery later once we
have it as read-write back.
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
