Files
Eric Biggers e95d36bd87 fs-verity: prototype implementation
Add the fs-verity shared code in fs/verity/, along with supporting
fields in struct inode and struct super_block.  Filesystems can hook
into this library to implement efficient file-level integrity and/or
authenticity for read-only files.  It works by implementing the
dm-verity mechanism at a file-granular level, using a Merkle tree to
verify any block in the file in log(file size) time.

fs-verity is a major new VFS feature that will take some time to get
right.  This prototype may be incompatible with the version that
eventually gets upstreamed.  If you would like to participate in the
design and implementation, please do so on the linux-fscrypt mailing
list [1].  Note that this will be a topic of discussion at LSF/MM 2018.

The Merkle tree is stored in-line with the file contents, starting at
the block past the original i_size.  A footer is stored after the Merkle
tree describing the original i_size, properties of the Merkle tree, and
other information.  The metadata is generated using a userspace tool;
then, an ioctl tells the kernel to enable fs-verity.  The metadata is
not stored in an xattr because the Merkle tree may be much larger than
XATTR_SIZE_MAX, and in the case of fs-verity combined with fscrypt it's
desirable for the metadata to be encrypted to avoid leaking plaintext
hashes.

In this prototype, an ioctl FS_IOC_SET_VERITY_MEASUREMENT tells the
kernel which measurement (hash of root hash + fs-verity footer) to
expect for a given inode, pinning it into memory.  Future work will
replace or supplement this with support for signature verification.

The i_size in the in-memory VFS inode is overridden so that userspace
only sees the original data, not the fs-verity metadata.  However, the
i_size stored on-disk remains the full i_size.

[1] http://vger.kernel.org/vger-lists.html#linux-fscrypt

Co-developed-by: Michael Halcrow <mhalcrow@google.com>
Signed-off-by: Michael Halcrow <mhalcrow@google.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>

(Backported to bluecross.  Tested full series with
 'android-xfstests -c f2fs -g verity')

Conflicts:
	fs/inode.c
	include/linux/fs.h

Bug: 30972906
Bug: 67380979
Change-Id: Idab791615fe06f4f64496f94b01edbc74f4849c4
2018-04-26 21:50:58 +00:00

316 lines
7.2 KiB
Plaintext

#
# File system configuration
#
menu "File systems"
# Use unaligned word dcache accesses
config DCACHE_WORD_ACCESS
bool
if BLOCK
config FS_IOMAP
bool
source "fs/ext2/Kconfig"
source "fs/ext4/Kconfig"
source "fs/jbd2/Kconfig"
config FS_MBCACHE
# Meta block cache for Extended Attributes (ext2/ext3/ext4)
tristate
default y if EXT2_FS=y && EXT2_FS_XATTR
default y if EXT4_FS=y
default m if EXT2_FS_XATTR || EXT4_FS
source "fs/reiserfs/Kconfig"
source "fs/jfs/Kconfig"
source "fs/xfs/Kconfig"
source "fs/gfs2/Kconfig"
source "fs/ocfs2/Kconfig"
source "fs/btrfs/Kconfig"
source "fs/nilfs2/Kconfig"
source "fs/f2fs/Kconfig"
config FS_DAX
bool "Direct Access (DAX) support"
depends on MMU
depends on !(ARM || MIPS || SPARC)
help
Direct Access (DAX) can be used on memory-backed block devices.
If the block device supports DAX and the filesystem supports DAX,
then you can avoid using the pagecache to buffer I/Os. Turning
on this option will compile in support for DAX; you will need to
mount the filesystem using the -o dax option.
If you do not have a block device that is capable of using this,
or if unsure, say N. Saying Y will increase the size of the kernel
by about 5kB.
config FS_DAX_PMD
bool
default FS_DAX
depends on FS_DAX
depends on ZONE_DEVICE
depends on TRANSPARENT_HUGEPAGE
depends on BROKEN
endif # BLOCK
# Posix ACL utility routines
#
# Note: Posix ACLs can be implemented without these helpers. Never use
# this symbol for ifdefs in core code.
#
config FS_POSIX_ACL
def_bool n
config EXPORTFS
tristate
config EXPORTFS_BLOCK_OPS
bool "Enable filesystem export operations for block IO"
help
This option enables the export operations for a filesystem to support
external block IO.
config FILE_LOCKING
bool "Enable POSIX file locking API" if EXPERT
default y
select PERCPU_RWSEM
help
This option enables standard file locking support, required
for filesystems like NFS and for the flock() system
call. Disabling this option saves about 11k.
config MANDATORY_FILE_LOCKING
bool "Enable Mandatory file locking"
depends on FILE_LOCKING
default y
help
This option enables files appropriately marked files on appropriely
mounted filesystems to support mandatory locking.
To the best of my knowledge this is dead code that no one cares about.
source "fs/crypto/Kconfig"
source "fs/verity/Kconfig"
source "fs/notify/Kconfig"
source "fs/quota/Kconfig"
source "fs/autofs4/Kconfig"
source "fs/fuse/Kconfig"
source "fs/overlayfs/Kconfig"
menu "Caches"
source "fs/fscache/Kconfig"
source "fs/cachefiles/Kconfig"
endmenu
if BLOCK
menu "CD-ROM/DVD Filesystems"
source "fs/isofs/Kconfig"
source "fs/udf/Kconfig"
endmenu
endif # BLOCK
if BLOCK
menu "DOS/FAT/NT Filesystems"
source "fs/fat/Kconfig"
source "fs/ntfs/Kconfig"
endmenu
endif # BLOCK
menu "Pseudo filesystems"
source "fs/proc/Kconfig"
source "fs/kernfs/Kconfig"
source "fs/sysfs/Kconfig"
config TMPFS
bool "Tmpfs virtual memory file system support (former shm fs)"
depends on SHMEM
help
Tmpfs is a file system which keeps all files in virtual memory.
Everything in tmpfs is temporary in the sense that no files will be
created on your hard drive. The files live in memory and swap
space. If you unmount a tmpfs instance, everything stored therein is
lost.
See <file:Documentation/filesystems/tmpfs.txt> for details.
config TMPFS_POSIX_ACL
bool "Tmpfs POSIX Access Control Lists"
depends on TMPFS
select TMPFS_XATTR
select FS_POSIX_ACL
help
POSIX Access Control Lists (ACLs) support additional access rights
for users and groups beyond the standard owner/group/world scheme,
and this option selects support for ACLs specifically for tmpfs
filesystems.
If you've selected TMPFS, it's possible that you'll also need
this option as there are a number of Linux distros that require
POSIX ACL support under /dev for certain features to work properly.
For example, some distros need this feature for ALSA-related /dev
files for sound to work properly. In short, if you're not sure,
say Y.
To learn more about Access Control Lists, visit the POSIX ACLs for
Linux website <http://acl.bestbits.at/>.
config TMPFS_XATTR
bool "Tmpfs extended attributes"
depends on TMPFS
default n
help
Extended attributes are name:value pairs associated with inodes by
the kernel or by users (see the attr(5) manual page, or visit
<http://acl.bestbits.at/> for details).
Currently this enables support for the trusted.* and
security.* namespaces.
You need this for POSIX ACL support on tmpfs.
If unsure, say N.
config HUGETLBFS
bool "HugeTLB file system support"
depends on X86 || IA64 || SPARC64 || (S390 && 64BIT) || \
SYS_SUPPORTS_HUGETLBFS || BROKEN
help
hugetlbfs is a filesystem backing for HugeTLB pages, based on
ramfs. For architectures that support it, say Y here and read
<file:Documentation/vm/hugetlbpage.txt> for details.
If unsure, say N.
config HUGETLB_PAGE
def_bool HUGETLBFS
config ARCH_HAS_GIGANTIC_PAGE
bool
source "fs/configfs/Kconfig"
source "fs/efivarfs/Kconfig"
endmenu
menuconfig MISC_FILESYSTEMS
bool "Miscellaneous filesystems"
default y
---help---
Say Y here to get to see options for various miscellaneous
filesystems, such as filesystems that came from other
operating systems.
This option alone does not add any kernel code.
If you say N, all options in this submenu will be skipped and
disabled; if unsure, say Y here.
if MISC_FILESYSTEMS
source "fs/orangefs/Kconfig"
source "fs/adfs/Kconfig"
source "fs/affs/Kconfig"
source "fs/ecryptfs/Kconfig"
source "fs/sdcardfs/Kconfig"
source "fs/hfs/Kconfig"
source "fs/hfsplus/Kconfig"
source "fs/befs/Kconfig"
source "fs/bfs/Kconfig"
source "fs/efs/Kconfig"
source "fs/jffs2/Kconfig"
# UBIFS File system configuration
source "fs/ubifs/Kconfig"
source "fs/logfs/Kconfig"
source "fs/cramfs/Kconfig"
source "fs/squashfs/Kconfig"
source "fs/freevxfs/Kconfig"
source "fs/minix/Kconfig"
source "fs/omfs/Kconfig"
source "fs/hpfs/Kconfig"
source "fs/qnx4/Kconfig"
source "fs/qnx6/Kconfig"
source "fs/romfs/Kconfig"
source "fs/pstore/Kconfig"
source "fs/sysv/Kconfig"
source "fs/ufs/Kconfig"
source "fs/exofs/Kconfig"
endif # MISC_FILESYSTEMS
source "fs/exofs/Kconfig.ore"
menuconfig NETWORK_FILESYSTEMS
bool "Network File Systems"
default y
depends on NET
---help---
Say Y here to get to see options for network filesystems and
filesystem-related networking code, such as NFS daemon and
RPCSEC security modules.
This option alone does not add any kernel code.
If you say N, all options in this submenu will be skipped and
disabled; if unsure, say Y here.
if NETWORK_FILESYSTEMS
source "fs/nfs/Kconfig"
source "fs/nfsd/Kconfig"
config GRACE_PERIOD
tristate
config LOCKD
tristate
depends on FILE_LOCKING
select GRACE_PERIOD
config LOCKD_V4
bool
depends on NFSD_V3 || NFS_V3
depends on FILE_LOCKING
default y
config NFS_ACL_SUPPORT
tristate
select FS_POSIX_ACL
config NFS_COMMON
bool
depends on NFSD || NFS_FS || LOCKD
default y
source "net/sunrpc/Kconfig"
source "fs/ceph/Kconfig"
source "fs/cifs/Kconfig"
source "fs/ncpfs/Kconfig"
source "fs/coda/Kconfig"
source "fs/afs/Kconfig"
source "fs/9p/Kconfig"
endif # NETWORK_FILESYSTEMS
source "fs/nls/Kconfig"
source "fs/dlm/Kconfig"
endmenu