From: Eric Biggers <ebiggers@xxxxxxxxxx> Add a test which verifies that dentries in an encrypted directory are invalidated when an encryption key is added --- which should cause the plaintext filenames to be visible and accessible, replacing the encoded ciphertext filenames and any negative dentries for the plaintext names. This primarily tests for a bug which was fixed in the v4.5 kernel, plus a v4.6 fix for incorrect RCU usage in the earlier fix. Cc: linux-fscrypt@xxxxxxxxxxxxxxx Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx> --- .gitignore | 1 + common/encrypt | 42 ++++++++--- src/Makefile | 2 +- src/t_encrypted_d_revalidate.c | 122 ++++++++++++++++++++++++++++++++ tests/generic/600 | 154 +++++++++++++++++++++++++++++++++++++++++ tests/generic/600.out | 37 ++++++++++ tests/generic/group | 1 + 7 files changed, 349 insertions(+), 10 deletions(-) create mode 100644 src/t_encrypted_d_revalidate.c create mode 100755 tests/generic/600 create mode 100644 tests/generic/600.out diff --git a/.gitignore b/.gitignore index b609f10f..38f3a001 100644 --- a/.gitignore +++ b/.gitignore @@ -112,6 +112,7 @@ /src/t_dir_offset /src/t_dir_offset2 /src/t_dir_type +/src/t_encrypted_d_revalidate /src/t_futimens /src/t_getcwd /src/t_holes diff --git a/common/encrypt b/common/encrypt index 85f71d5b..723f1b11 100644 --- a/common/encrypt +++ b/common/encrypt @@ -84,25 +84,34 @@ _new_session_keyring() $KEYCTL_PROG new_session >>$seqres.full } -# -# Generate a random encryption key, add it to the session keyring, and print out -# the resulting key descriptor (example: "8bf798e1a494e1ec"). Requires the -# keyctl program. It's assumed the caller has already set up a test-scoped -# session keyring using _new_session_keyring. -# -_generate_encryption_key() +# Generate a key descriptor (16 character hex string) +_generate_key_descriptor() { - # Generate a key descriptor (16 character hex string) local keydesc="" + local i for ((i = 0; i < 8; i++)); do keydesc="${keydesc}$(printf "%02x" $(( $RANDOM % 256 )))" done + echo $keydesc +} - # Generate the actual encryption key (64 bytes) +# Generate a raw encryption key, but don't add it to the keyring yet. +_generate_raw_encryption_key() +{ local raw="" + local i for ((i = 0; i < 64; i++)); do raw="${raw}\\x$(printf "%02x" $(( $RANDOM % 256 )))" done + echo $raw +} + +# Add the specified raw encryption key to the session keyring, using the +# specified key descriptor. +_add_encryption_key() +{ + local keydesc=$1 + local raw=$2 # # Add the key to the session keyring. The required structure is: @@ -134,6 +143,21 @@ _generate_encryption_key() fi echo -n -e "${mode}${raw}${size}" | $KEYCTL_PROG padd logon $FSTYP:$keydesc @s >>$seqres.full +} + +# +# Generate a random encryption key, add it to the session keyring, and print out +# the resulting key descriptor (example: "8bf798e1a494e1ec"). Requires the +# keyctl program. It's assumed the caller has already set up a test-scoped +# session keyring using _new_session_keyring. +# +_generate_encryption_key() +{ + local keydesc=$(_generate_key_descriptor) + local raw=$(_generate_raw_encryption_key) + + _add_encryption_key $keydesc $raw + echo $keydesc } diff --git a/src/Makefile b/src/Makefile index f1338ca9..e5042c9b 100644 --- a/src/Makefile +++ b/src/Makefile @@ -22,7 +22,7 @@ LINUX_TARGETS = xfsctl bstat t_mtab getdevicesize preallo_rw_pattern_reader \ seek_copy_test t_readdir_1 t_readdir_2 fsync-tester nsexec cloner \ renameat2 t_getcwd e4compact test-nextquota punch-alternating \ attr-list-by-handle-cursor-test listxattr dio-interleaved t_dir_type \ - dio-invalidate-cache stat_test + dio-invalidate-cache stat_test t_encrypted_d_revalidate SUBDIRS = diff --git a/src/t_encrypted_d_revalidate.c b/src/t_encrypted_d_revalidate.c new file mode 100644 index 00000000..2cfd9834 --- /dev/null +++ b/src/t_encrypted_d_revalidate.c @@ -0,0 +1,122 @@ +/* + * t_encrypted_d_revalidate + * + * Test that ->d_revalidate() for encrypted dentries doesn't oops the + * kernel by incorrectly not dropping out of RCU mode. To do this, try + * to look up a negative dentry while another thread deletes its parent + * directory. Fixed by commit 03a8bb0e53d9 ("ext4/fscrypto: avoid RCU + * lookup in d_revalidate"). + * + * This doesn't always reproduce reliably, but we give it a few seconds. + * + * ---------------------------------------------------------------------------- + * + * Copyright (c) 2017 Google, Inc. All Rights Reserved. + * + * Author: Eric Biggers <ebiggers@xxxxxxxxxx> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public Licence as published by + * the Free Software Foundation; either version 2 of the Licence, or (at + * your option) any later version. + * + * This program is distributed in the hope that it would be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, see <http://www.gnu.org/licenses/>. + */ + +#include <errno.h> +#include <pthread.h> +#include <signal.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <sys/stat.h> +#include <unistd.h> + +#define TIMEOUT 10 +#define DIR_NAME "dir" +#define FILE_NAME DIR_NAME "/file" + +static volatile sig_atomic_t timed_out = 0; + +static void alarm_handler(int sig) +{ + timed_out = 1; +} + +static void __attribute__((noreturn)) +die(int err, const char *msg) +{ + fprintf(stderr, "ERROR: %s", msg); + if (err) + fprintf(stderr, ": %s", strerror(err)); + fputc('\n', stderr); + exit(1); +} + +static void *stat_thread(void *_arg) +{ + struct stat stbuf; + + for (;;) { + if (stat(FILE_NAME, &stbuf) == 0) + die(0, "stat should have failed"); + if (errno != ENOENT) + die(errno, "stat"); + } +} + +int main(int argc, char *argv[]) +{ + long ncpus; + long num_stat_threads; + long i; + struct stat stbuf; + + if (argc != 2) { + fprintf(stderr, "Usage: %s DIR\n", argv[0]); + return 2; + } + + if (chdir(argv[1]) != 0) + die(errno, "chdir"); + + ncpus = sysconf(_SC_NPROCESSORS_ONLN); + if (ncpus > 1) + num_stat_threads = ncpus - 1; + else + num_stat_threads = 1; + + for (i = 0; i < num_stat_threads; i++) { + pthread_t thread; + int err; + + err = pthread_create(&thread, NULL, stat_thread, NULL); + if (err) + die(err, "pthread_create"); + } + + if (signal(SIGALRM, alarm_handler) == SIG_ERR) + die(errno, "signal"); + + alarm(TIMEOUT); + + while (!timed_out) { + if (mkdir(DIR_NAME, 0777) != 0) + die(errno, "mkdir"); + if (stat(FILE_NAME, &stbuf) == 0) + die(0, "stat should have failed"); + if (errno != ENOENT) + die(errno, "stat"); + if (rmdir(DIR_NAME) != 0) + die(errno, "rmdir"); + } + + printf("t_encrypted_d_revalidate finished\n"); + return 0; +} diff --git a/tests/generic/600 b/tests/generic/600 new file mode 100755 index 00000000..135f9f29 --- /dev/null +++ b/tests/generic/600 @@ -0,0 +1,154 @@ +#! /bin/bash +# FS QA Test generic/600 +# +# Test that encrypted dentries are revalidated after adding a key. +# Regression test for: +# 28b4c263961c ("ext4 crypto: revalidate dentry after adding or removing the key") +# +# Furthermore, test that encrypted directories are *not* revalidated after +# "revoking" a key. This used to be done, but it was broken and was removed by: +# 1b53cf9815bb ("fscrypt: remove broken support for detecting keyring key revocation") +# +# Also test for a race condition bug in 28b4c263961c, fixed by: +# 03a8bb0e53d9 ("ext4/fscrypto: avoid RCU lookup in d_revalidate") +# +# Note: the following fix for another race in 28b4c263961c should be applied as +# well, though we don't test for it because it's very difficult to reproduce: +# 3d43bcfef5f0 ("ext4 crypto: use dget_parent() in ext4_d_revalidate()") +# +#----------------------------------------------------------------------- +# Copyright (c) 2017 Google, Inc. All Rights Reserved. +# +# Author: Eric Biggers <ebiggers@xxxxxxxxxx> +# +# This program is free software; you can redistribute it and/or +# modify it under the terms of the GNU General Public License as +# published by the Free Software Foundation. +# +# This program is distributed in the hope that it would be useful, +# but WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +# GNU General Public License for more details. +# +# You should have received a copy of the GNU General Public License +# along with this program; if not, write the Free Software Foundation, +# Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA +#----------------------------------------------------------------------- +# + +seq=`basename $0` +seqres=$RESULT_DIR/$seq +echo "QA output created by $seq" + +here=`pwd` +tmp=/tmp/$$ +status=1 # failure is the default! +trap "_cleanup; exit \$status" 0 1 2 3 15 + +_cleanup() +{ + cd / + rm -f $tmp.* +} + +# get standard environment, filters and checks +. ./common/rc +. ./common/filter +. ./common/encrypt + +# remove previous $seqres.full before test +rm -f $seqres.full + +# real QA test starts here +_supported_fs generic +_supported_os Linux +_require_scratch_encryption +_require_xfs_io_command "set_encpolicy" +_require_command "$KEYCTL_PROG" keyctl +_require_test_program "t_encrypted_d_revalidate" + +# Set up an encrypted directory +_scratch_mkfs_encrypted &>> $seqres.full +_scratch_mount +_new_session_keyring +keydesc=$(_generate_key_descriptor) +raw_key=$(_generate_raw_encryption_key) +mkdir $SCRATCH_MNT/edir +_add_encryption_key $keydesc $raw_key +$XFS_IO_PROG -c "set_encpolicy $keydesc" $SCRATCH_MNT/edir + +# Create two files in the directory: one whose name is valid in the base64 +# format used for encoding ciphertext filenames, and one whose name is not. The +# exact filenames *should* be irrelevant, but due to yet another bug, ->lookup() +# in an encrypted directory without the key returned ERR_PTR(-ENOENT) rather +# than NULL if the name was not valid ciphertext, causing a negative dentry to +# not be created. For the purpose of this test, we want at least one negative +# dentry to be created, so just create both types of name. +echo contents_@@@ > $SCRATCH_MNT/edir/@@@ # not valid base64 +echo contents_abcd > $SCRATCH_MNT/edir/abcd # valid base64 + +_filter_ciphertext_filenames() +{ + _filter_scratch | sed 's|edir/[a-zA-Z0-9+,_]\+|edir/ENCRYPTED_NAME|g' +} + +_show_file_contents() +{ + echo "--- Contents of files using plaintext names:" + cat $SCRATCH_MNT/edir/@@@ |& _filter_scratch + cat $SCRATCH_MNT/edir/abcd |& _filter_scratch + echo "--- Contents of files using ciphertext names:" + cat ${ciphertext_names[@]} |& _filter_ciphertext_filenames +} + +_show_directory_with_key() +{ + echo "--- Directory listing:" + find $SCRATCH_MNT/edir -mindepth 1 | sort | _filter_scratch + _show_file_contents +} + +# View the directory without the encryption key. The plaintext names shouldn't +# exist, but 'cat' each to verify this, which also should create negative +# dentries. The ciphertext names are unpredictable by design, but verify that +# the correct number of them are listed by readdir, and save them for later. +echo +echo "***** Without encryption key *****" +_unlink_encryption_key $keydesc +_scratch_cycle_mount +echo "--- Directory listing:" +ciphertext_names=( $(find $SCRATCH_MNT/edir -mindepth 1 | sort) ) +printf '%s\n' "${ciphertext_names[@]}" | _filter_ciphertext_filenames +_show_file_contents + +# Without remounting or dropping caches, add the encryption key and view the +# directory again. Now the plaintext names should all be there, and the +# ciphertext names should be gone. Make sure to 'cat' all the names to test for +# stale dentries. +echo +echo "***** With encryption key *****" +_add_encryption_key $keydesc $raw_key +_show_directory_with_key + +# Test for ->d_revalidate() race conditions. +echo +echo "***** Race conditions *****" +$here/src/t_encrypted_d_revalidate $SCRATCH_MNT/edir +rm -rf $SCRATCH_MNT/edir/dir + +# Now open the files to pin them in the inode cache (needed to make the test +# reliable), then revoke the encryption key. This should no longer cause the +# files to be presented in ciphertext form immediately. +echo +echo "***** After key revocation *****" +( + exec 3<$SCRATCH_MNT/edir + exec 4<$SCRATCH_MNT/edir/@@@ + exec 5<$SCRATCH_MNT/edir/abcd + _revoke_encryption_key $keydesc + _show_directory_with_key +) + +# success, all done +status=0 +exit diff --git a/tests/generic/600.out b/tests/generic/600.out new file mode 100644 index 00000000..34bf6aab --- /dev/null +++ b/tests/generic/600.out @@ -0,0 +1,37 @@ +QA output created by 600 + +***** Without encryption key ***** +--- Directory listing: +SCRATCH_MNT/edir/ENCRYPTED_NAME +SCRATCH_MNT/edir/ENCRYPTED_NAME +--- Contents of files using plaintext names: +cat: SCRATCH_MNT/edir/@@@: No such file or directory +cat: SCRATCH_MNT/edir/abcd: No such file or directory +--- Contents of files using ciphertext names: +cat: SCRATCH_MNT/edir/ENCRYPTED_NAME: Required key not available +cat: SCRATCH_MNT/edir/ENCRYPTED_NAME: Required key not available + +***** With encryption key ***** +--- Directory listing: +SCRATCH_MNT/edir/@@@ +SCRATCH_MNT/edir/abcd +--- Contents of files using plaintext names: +contents_@@@ +contents_abcd +--- Contents of files using ciphertext names: +cat: SCRATCH_MNT/edir/ENCRYPTED_NAME: No such file or directory +cat: SCRATCH_MNT/edir/ENCRYPTED_NAME: No such file or directory + +***** Race conditions ***** +t_encrypted_d_revalidate finished + +***** After key revocation ***** +--- Directory listing: +SCRATCH_MNT/edir/@@@ +SCRATCH_MNT/edir/abcd +--- Contents of files using plaintext names: +contents_@@@ +contents_abcd +--- Contents of files using ciphertext names: +cat: SCRATCH_MNT/edir/ENCRYPTED_NAME: No such file or directory +cat: SCRATCH_MNT/edir/ENCRYPTED_NAME: No such file or directory diff --git a/tests/generic/group b/tests/generic/group index b3051752..edfc99a6 100644 --- a/tests/generic/group +++ b/tests/generic/group @@ -431,3 +431,4 @@ 426 auto quick exportfs 427 auto quick aio rw 428 auto quick +600 auto encrypt -- 2.13.0.rc1.294.g07d810a77f-goog -- To unsubscribe from this list: send the line "unsubscribe linux-fscrypt" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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