From: Eric Biggers <ebiggers@xxxxxxxxxx> Add common functions for setting up and testing fs-verity, a new feature for read-only file-based authenticity protection. fs-verity will be supported by ext4 and f2fs, and perhaps by other filesystems later. Running the fs-verity tests requires: - A kernel with the fs-verity patches from https://git.kernel.org/pub/scm/linux/kernel/git/ebiggers/linux.git branch "fsverity" and configured with CONFIG_FS_VERITY. - The fsverity utility program from https://git.kernel.org/pub/scm/linux/kernel/git/ebiggers/fsverity-utils.git - e2fsprogs v1.45.2 or later for ext4 tests, or f2fs-tools v1.11.0 or later for f2fs tests. See the file Documentation/filesystems/fsverity.rst in the kernel tree for more information about fs-verity. Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx> --- common/config | 1 + common/verity | 199 ++++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 200 insertions(+) create mode 100644 common/verity diff --git a/common/config b/common/config index bd64be62..001ddc45 100644 --- a/common/config +++ b/common/config @@ -212,6 +212,7 @@ export CHECKBASHISMS_PROG="$(type -P checkbashisms)" export XFS_INFO_PROG="$(type -P xfs_info)" export DUPEREMOVE_PROG="$(type -P duperemove)" export CC_PROG="$(type -P cc)" +export FSVERITY_PROG="$(type -P fsverity)" # use 'udevadm settle' or 'udevsettle' to wait for lv to be settled. # newer systems have udevadm command but older systems like RHEL5 don't. diff --git a/common/verity b/common/verity new file mode 100644 index 00000000..a8aae51e --- /dev/null +++ b/common/verity @@ -0,0 +1,199 @@ +# SPDX-License-Identifier: GPL-2.0 +# Copyright 2018 Google LLC +# +# Functions for setting up and testing fs-verity + +_require_scratch_verity() +{ + _require_scratch + _require_command "$FSVERITY_PROG" fsverity + + if ! _scratch_mkfs_verity &>>$seqres.full; then + # ext4: need e2fsprogs v1.44.5 or later (but actually v1.45.2+ + # is needed for some tests to pass, due to an e2fsck bug) + # f2fs: need f2fs-tools v1.11.0 or later + _notrun "$FSTYP userspace tools don't support fs-verity" + fi + + # Try to mount the filesystem. If this fails then either the kernel + # isn't aware of fs-verity, or the mkfs options were not compatible with + # verity (e.g. ext4 with block size != PAGE_SIZE). + if ! _try_scratch_mount &>>$seqres.full; then + _notrun "kernel is unaware of $FSTYP verity feature," \ + "or mkfs options are not compatible with verity" + fi + + # The filesystem may be aware of fs-verity but have it disabled by + # CONFIG_FS_VERITY=n. Detect support via sysfs. + if [ ! -e /sys/fs/$FSTYP/features/verity ]; then + _notrun "kernel $FSTYP isn't configured with verity support" + fi + + # The filesystem may have fs-verity enabled but not actually usable by + # default. E.g., ext4 only supports verity on extent-based files, so it + # doesn't work on ext3-style filesystems. So, try actually using it. + echo foo > $SCRATCH_MNT/tmpfile + if ! _fsv_enable $SCRATCH_MNT/tmpfile; then + _notrun "$FSTYP verity isn't usable by default with these mkfs options" + fi + rm -f $SCRATCH_MNT/tmpfile + + _scratch_unmount + + # Merkle tree block size. Currently all filesystems only support + # PAGE_SIZE for this. This is also the default for 'fsverity enable'. + FSV_BLOCK_SIZE=$(get_page_size) +} + +_scratch_mkfs_verity() +{ + case $FSTYP in + ext4|f2fs) + _scratch_mkfs -O verity + ;; + *) + _notrun "No verity support for $FSTYP" + ;; + esac +} + +_scratch_mkfs_encrypted_verity() +{ + case $FSTYP in + ext4) + _scratch_mkfs -O encrypt,verity + ;; + f2fs) + # f2fs-tools as of v1.11.0 doesn't allow comma-separated + # features with -O. Instead -O must be supplied multiple times. + _scratch_mkfs -O encrypt -O verity + ;; + *) + _notrun "$FSTYP not supported in _scratch_mkfs_encrypted_verity" + ;; + esac +} + +_fsv_scratch_begin_subtest() +{ + local msg=$1 + + rm -rf "${SCRATCH_MNT:?}"/* + echo -e "\n# $msg" +} + +_fsv_enable() +{ + $FSVERITY_PROG enable "$@" +} + +_fsv_measure() +{ + $FSVERITY_PROG measure "$@" | awk '{print $1}' +} + +# Generate a file, then enable verity on it. +_fsv_create_enable_file() +{ + local file=$1 + shift + + head -c $((FSV_BLOCK_SIZE * 2)) /dev/zero > "$file" + _fsv_enable "$file" "$@" +} + +_fsv_have_hash_algorithm() +{ + local hash_alg=$1 + local test_file=$2 + + rm -f $test_file + head -c 4096 /dev/zero > $test_file + if ! _fsv_enable --hash-alg=$hash_alg $test_file &>> $seqres.full; then + # no kernel support + return 1 + fi + rm -f $test_file + return 0 +} + +# +# _fsv_scratch_corrupt_bytes - Write some bytes to a file, bypassing the filesystem +# +# Write the bytes sent on stdin to the given offset in the given file, but do so +# by writing directly to the extents on the block device, with the filesystem +# unmounted. This can be used to corrupt a verity file for testing purposes, +# bypassing the restrictions imposed by the filesystem. +# +# The file is assumed to be located on $SCRATCH_DEV. +# +_fsv_scratch_corrupt_bytes() +{ + local file=$1 + local offset=$2 + local lstart lend pstart pend + local dd_cmds=() + local cmd + + sync # Sync to avoid unwritten extents + + cat > $tmp.bytes + local end=$(( offset + $(stat -c %s $tmp.bytes ) )) + + # For each extent that intersects the requested range in order, add a + # command that writes the next part of the data to that extent. + while read -r lstart lend pstart pend; do + lstart=$((lstart * 512)) + lend=$(((lend + 1) * 512)) + pstart=$((pstart * 512)) + pend=$(((pend + 1) * 512)) + + if (( lend - lstart != pend - pstart )); then + _fail "Logical and physical extent lengths differ for file '$file'" + elif (( offset < lstart )); then + _fail "Hole in file '$file' at byte $offset. Next extent begins at byte $lstart" + elif (( offset < lend )); then + local len=$((lend - offset)) + local seek=$((pstart + (offset - lstart))) + dd_cmds+=("head -c $len | dd of=$SCRATCH_DEV oflag=seek_bytes seek=$seek status=none") + (( offset += len )) + fi + done < <($XFS_IO_PROG -r -c "fiemap $offset $((end - offset))" "$file" \ + | _filter_xfs_io_fiemap) + + if (( offset < end )); then + _fail "Extents of file '$file' ended at byte $offset, but needed until $end" + fi + + # Execute the commands to write the data + _scratch_unmount + for cmd in "${dd_cmds[@]}"; do + eval "$cmd" + done < $tmp.bytes + sync # Sync to flush the block device's pagecache + _scratch_mount +} + +# +# _fsv_scratch_corrupt_merkle_tree - Corrupt a file's Merkle tree +# +# Like _fsv_scratch_corrupt_bytes(), but this corrupts the file's fs-verity +# Merkle tree. The offset is given as a byte offset into the Merkle tree. +# +_fsv_scratch_corrupt_merkle_tree() +{ + local file=$1 + local offset=$2 + + case $FSTYP in + ext4|f2fs) + # ext4 and f2fs store the Merkle tree after the file contents + # itself, starting at the next 65536-byte aligned boundary. + (( offset += ($(stat -c %s $file) + 65535) & ~65535 )) + _fsv_scratch_corrupt_bytes $file $offset + ;; + *) + _fail "_fsv_scratch_corrupt_merkle_tree() unimplemented on $FSTYP" + ;; + esac +} -- 2.22.0.410.gd8fdbe21b5-goog
