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e17fe6579d
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Eric Biggers e17fe6579d fs-verity: add FS_IOC_READ_VERITY_METADATA ioctl 
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>
2021-02-07 14:51:11 -08:00
..
9p 9p for 5.11-rc1 2020-12-21 10:28:02 -08:00
adfs Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-10-24 12:26:05 -07:00
affs Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-10-24 12:26:05 -07:00
afs afs: Fix directory entry size calculation 2021-01-04 12:25:19 +00:00
autofs file: Replace ksys_close with close_fd 2020-12-10 12:42:59 -06:00
befs [PATCH] reduce boilerplate in fsid handling 2020-09-18 16:45:50 -04:00
bfs bfs: don't use WARNING: string when it's just info. 2020-12-15 22:46:18 -08:00
btrfs for-5.11-rc4-tag 2021-01-20 14:15:33 -08:00
cachefiles cachefiles: Drop superfluous readpages aops NULL check 2021-01-20 11:33:51 -08:00
ceph libceph, ceph: disambiguate ceph_connection_operations handlers 2021-01-04 17:31:32 +01:00
cifs cifs: do not fail __smb_send_rqst if non-fatal signals are pending 2021-01-23 01:28:20 -06:00
coda docs: filesystems: convert coda.txt to ReST 2020-05-05 09:22:21 -06:00
configfs configfs: fix kernel-doc markup issue 2020-11-14 10:22:45 +01:00
cramfs [PATCH] reduce boilerplate in fsid handling 2020-09-18 16:45:50 -04:00
crypto f2fs-for-5.11-rc1 2020-12-17 11:18:00 -08:00
debugfs debugfs: remove return value of debugfs_create_devm_seqfile() 2020-10-30 08:37:39 +01:00
devpts
dlm fs: dlm: check on existing node address 2020-11-10 12:14:20 -06:00
ecryptfs mm, treewide: rename kzfree() to kfree_sensitive() 2020-08-07 11:33:22 -07:00
efivarfs efivarfs: revert "fix memory leak in efivarfs_create()" 2020-11-25 16:55:02 +01:00
efs [PATCH] reduce boilerplate in fsid handling 2020-09-18 16:45:50 -04:00
erofs erofs: avoid using generic_block_bmap 2020-12-10 11:07:40 +08:00
exfat exfat: Avoid allocating upcase table using kcalloc() 2020-12-22 12:31:17 +09:00
exportfs exportfs: Add a function to return the raw output from fh_to_dentry() 2020-12-09 09:39:38 -05:00
ext2 ext2: Fix fall-through warnings for Clang 2020-11-23 10:36:53 +01:00
ext4 fs-verity: add FS_IOC_READ_VERITY_METADATA ioctl 2021-02-07 14:51:11 -08:00
f2fs fs-verity: add FS_IOC_READ_VERITY_METADATA ioctl 2021-02-07 14:51:11 -08:00
fat [PATCH] reduce boilerplate in fsid handling 2020-09-18 16:45:50 -04:00
freevxfs
fscache Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next 2020-06-03 16:27:18 -07:00
fuse fuse: fix bad inode 2020-12-10 15:33:14 +01:00
gfs2 gfs2: in signal_our_withdraw wait for unfreeze of _this_ fs only 2020-12-03 17:04:41 +01:00
hfs fs: Replace zero-length array with flexible-array member 2020-10-29 17:22:59 -05:00
hfsplus fs: Replace zero-length array with flexible-array member 2020-10-29 17:22:59 -05:00
hostfs fix hostfs_open() use of ->f_path.dentry 2020-12-21 21:42:29 -05:00
hpfs [PATCH] reduce boilerplate in fsid handling 2020-09-18 16:45:50 -04:00
hugetlbfs hugetlbfs: prevent filesystem stacking of hugetlbfs 2020-08-12 10:57:56 -07:00
iomap mm: memcontrol: Use helpers to read page's memcg data 2020-12-02 18:28:05 -08:00
isofs fs: Replace zero-length array with flexible-array member 2020-10-29 17:22:59 -05:00
jbd2 jbd2: add a helper to find out number of fast commit blocks 2020-12-17 13:30:45 -05:00
jffs2 jffs2: Fix NULL pointer dereference in rp_size fs option parsing 2020-12-13 21:57:21 +01:00
jfs jfs: Fix array index bounds check in dbAdjTree 2020-11-13 16:03:07 -06:00
kernfs kernfs: wire up ->splice_read and ->splice_write 2021-01-21 18:30:28 +01:00
lockd fs/lockd: convert comma to semicolon 2020-12-16 07:57:37 -05:00
minix [PATCH] reduce boilerplate in fsid handling 2020-09-18 16:45:50 -04:00
nfs NFS: nfs_igrab_and_active must first reference the superblock 2021-01-10 16:29:28 -05:00
nfs_common nfs_common: need lock during iterate through the list 2020-12-09 09:38:34 -05:00
nfsd nfsd4: readdirplus shouldn't return parent of export 2021-01-12 08:54:14 -05:00
nilfs2 fs/nilfs2: remove some unused macros to tame gcc 2020-12-15 22:46:17 -08:00
nls treewide: replace '---help---' in Kconfig files with 'help' 2020-06-14 01:57:21 +09:00
notify fanotify: Fix sys_fanotify_mark() on native x86-32 2020-12-28 11:58:59 +01:00
ntfs fs/ntfs: remove unused variable attr_len 2020-12-15 12:13:37 -08:00
ocfs2 ocfs2: ratelimit the 'max lookup times reached' notice 2020-12-15 12:13:37 -08:00
omfs fs: omfs: use kmemdup() rather than kmalloc+memcpy 2020-09-22 23:39:45 -04:00
openpromfs
orangefs orangefs: add splice file operations 2020-12-16 16:14:08 -05:00
overlayfs ovl: unprivieged mounts 2020-12-14 15:26:14 +01:00
proc proc_sysctl: fix oops caused by incorrect command parameters 2021-01-24 10:34:53 -08:00
pstore Tracing updates for 5.11 2020-12-17 13:22:17 -08:00
qnx4 [PATCH] reduce boilerplate in fsid handling 2020-09-18 16:45:50 -04:00
qnx6 [PATCH] reduce boilerplate in fsid handling 2020-09-18 16:45:50 -04:00
quota \n 2020-12-17 11:00:37 -08:00
ramfs ramfs: fix nommu mmap with gaps in the page cache 2020-10-16 11:11:22 -07:00
reiserfs reiserfs: add check for an invalid ih_entry_count 2020-11-26 16:57:28 +01:00
romfs Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-10-24 12:26:05 -07:00
squashfs Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-10-24 12:26:05 -07:00
sysfs sysfs: Add sysfs_emit and sysfs_emit_at to format sysfs output 2020-10-02 12:02:30 +02:00
sysv [PATCH] reduce boilerplate in fsid handling 2020-09-18 16:45:50 -04:00
tracefs
ubifs This pull request contains changes for JFFS2, UBI and UBIFS: 2020-12-17 17:46:34 -08:00
udf udf: fix the problem that the disc content is not displayed 2021-01-18 12:06:33 +01:00
ufs Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-10-24 12:26:05 -07:00
unicode unicode: Add utf8_casefold_hash 2020-09-10 14:03:31 -07:00
vboxsf Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2020-10-15 15:11:56 -07:00
verity fs-verity: add FS_IOC_READ_VERITY_METADATA ioctl 2021-02-07 14:51:11 -08:00
xfs New code for 5.11: 2020-12-18 12:50:18 -08:00
zonefs zonefs: select CONFIG_CRC32 2021-01-04 09:06:42 +09:00
aio.c Merge branch 'akpm' (patches from Andrew) 2020-12-15 12:53:37 -08:00
anon_inodes.c
attr.c
bad_inode.c fs: move the fiemap definitions out of fs.h 2020-06-03 23:16:55 -04:00
binfmt_aout.c exec: Rename flush_old_exec begin_new_exec 2020-05-07 16:55:47 -05:00
binfmt_elf_fdpic.c binfmt_elf, binfmt_elf_fdpic: use a VMA list snapshot 2020-10-16 11:11:21 -07:00
binfmt_elf.c Merge branch 'exec-for-v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2020-12-15 19:29:43 -08:00
binfmt_em86.c Merge branch 'akpm' (patches from Andrew) 2020-06-04 19:18:29 -07:00
binfmt_flat.c binfmt_flat: revert "binfmt_flat: don't offset the data start" 2020-08-24 08:49:13 +10:00
binfmt_misc.c Merge branch 'akpm' (patches from Andrew) 2020-06-04 19:18:29 -07:00
binfmt_script.c Merge branch 'akpm' (patches from Andrew) 2020-06-04 19:18:29 -07:00
block_dev.c block: pre-initialize struct block_device in bdev_alloc_inode 2021-01-07 20:57:53 -07:00
buffer.c for-5.11/block-2020-12-14 2020-12-16 12:57:51 -08:00
char_dev.c vfs: allow unprivileged whiteout creation 2020-05-14 16:44:23 +02:00
compat_binfmt_elf.c elf: Expose ELF header on arch_setup_additional_pages() 2020-10-26 13:46:47 +01:00
coredump.c Merge branch 'exec-for-v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2020-12-15 19:29:43 -08:00
d_path.c fs: fix NULL dereference due to data race in prepend_path() 2020-10-14 14:54:45 -07:00
dax.c mm: simplify follow_pte{,pmd} 2020-12-15 22:46:19 -08:00
dcache.c fs: Kill DCACHE_DONTCACHE dentry even if DCACHE_REFERENCED is set 2020-12-10 17:33:17 -05:00
dcookies.c
direct-io.c \n 2020-10-15 15:03:10 -07:00
drop_caches.c sysctl: pass kernel pointers to ->proc_handler 2020-04-27 02:07:40 -04:00
eventfd.c eventfd: Export eventfd_ctx_do_read() 2020-11-15 09:49:10 -05:00
eventpoll.c epoll: add syscall epoll_pwait2 2020-12-19 11:18:38 -08:00
exec.c Merge branch 'parisc-5.11-1' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux 2020-12-16 12:10:40 -08:00
fcntl.c fcntl: Fix potential deadlock in send_sig{io, urg}() 2020-11-05 07:44:15 -05:00
fhandle.c
file_table.c epoll: take epitem list out of struct file 2020-10-25 20:02:08 -04:00
file.c kernel/io_uring: cancel io_uring before task works 2020-12-30 19:36:54 -07:00
filesystems.c fs/filesystems.c: downgrade user-reachable WARN_ONCE() to pr_warn_once() 2020-04-10 15:36:22 -07:00
fs_context.c treewide: Use fallthrough pseudo-keyword 2020-08-23 17:36:59 -05:00
fs_parser.c fs_parse: mark fs_param_bad_value() as static 2020-10-13 18:38:27 -07:00
fs_pin.c
fs_struct.c vfs: Use sequence counter with associated spinlock 2020-07-29 16:14:27 +02:00
fs_types.c
fs-writeback.c fs: fix lazytime expiration handling in __writeback_single_inode() 2021-01-13 17:26:21 +01:00
fsopen.c treewide: Use fallthrough pseudo-keyword 2020-08-23 17:36:59 -05:00
init.c init: add an init_dup helper 2020-08-04 21:02:38 -04:00
inode.c Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-12-25 10:54:29 -08:00
internal.h for-5.11/block-2020-12-14 2020-12-16 12:57:51 -08:00
io_uring.c io_uring: account io_uring internal files as REQ_F_INFLIGHT 2021-01-24 10:15:33 -07:00
io-wq.c io-wq: kill now unused io_wq_cancel_all() 2020-12-20 10:47:42 -07:00
io-wq.h io-wq: kill now unused io_wq_cancel_all() 2020-12-20 10:47:42 -07:00
ioctl.c fs: remove ksys_ioctl 2020-07-31 08:16:01 +02:00
Kconfig tmpfs: support 64-bit inums per-sb 2020-08-07 11:33:24 -07:00
Kconfig.binfmt treewide: replace '---help---' in Kconfig files with 'help' 2020-06-14 01:57:21 +09:00
kernel_read_file.c fs/kernel_file_read: Add "offset" arg for partial reads 2020-10-05 13:37:04 +02:00
libfs.c f2fs-for-5.11-rc1 2020-12-17 11:18:00 -08:00
locks.c Merge branch 'exec-for-v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2020-12-15 19:29:43 -08:00
Makefile Refactored code for 5.10: 2020-10-23 11:33:41 -07:00
mbcache.c
mount.h mnt: Use generic ns_common::count 2020-08-19 14:14:19 +02:00
mpage.c fs: convert mpage_readpages to mpage_readahead 2020-06-02 10:59:07 -07:00
namei.c Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-12-25 10:54:29 -08:00
namespace.c umount(2): move the flag validity checks first 2021-01-04 15:31:58 -05:00
no-block.c
nsfs.c nsproxy: attach to namespaces via pidfds 2020-05-13 11:41:22 +02:00
open.c Merge branch 'exec-for-v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2020-12-15 19:29:43 -08:00
pipe.c block: remove i_bdev 2020-12-01 14:53:39 -07:00
pnode.c propagate_one(): mnt_set_mountpoint() needs mount_lock 2020-04-27 10:37:14 -04:00
pnode.h fs/namespace.c: WARN if mnt_count has become negative 2020-12-10 17:33:17 -05:00
posix_acl.c vfs: clean up posix_acl_permission() logic aroudn MAY_NOT_BLOCK 2020-06-08 11:04:19 -07:00
proc_namespace.c proc mountinfo: make splice available again 2020-12-27 12:00:36 -08:00
read_write.c Refactored code for 5.10: 2020-10-23 11:33:41 -07:00
readdir.c fs: remove ksys_getdents64 2020-07-31 08:16:00 +02:00
remap_range.c vfs: verify source area in vfs_dedupe_file_range_one() 2020-12-14 15:26:13 +01:00
select.c poll: fix performance regression due to out-of-line __put_user() 2021-01-08 11:06:29 -08:00
seq_file.c fix return values of seq_read_iter() 2020-11-15 22:12:53 -05:00
signalfd.c treewide: Use fallthrough pseudo-keyword 2020-08-23 17:36:59 -05:00
splice.c io_uring-5.10-2020-10-24 2020-10-24 12:40:18 -07:00
stack.c
stat.c fs: remove KSTAT_QUERY_FLAGS 2020-09-26 22:55:05 -04:00
statfs.c block: remove i_bdev 2020-12-01 14:53:39 -07:00
super.c block: remove i_bdev 2020-12-01 14:53:39 -07:00
sync.c overlayfs update for 5.8 2020-06-09 15:40:50 -07:00
timerfd.c
userfaultfd.c userfaultfd: add user-mode only option to unprivileged_userfaultfd sysctl knob 2020-12-15 12:13:46 -08:00
utimes.c fs: expose utimes_common 2020-07-31 08:16:01 +02:00
xattr.c vfs: move cap_convert_nscap() call into vfs_setxattr() 2020-12-14 15:26:13 +01:00