| Message ID | 20210522004132.2142563-1-drosen@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | ext4: Fix no-key deletion for encrypt+casefold | expand |
On Sat, May 22, 2021 at 12:41:32AM +0000, Daniel Rosenberg wrote: > commit 471fbbea7ff7 ("ext4: handle casefolding with encryption") is > missing a few checks for the encryption key which are needed to > support deleting enrypted casefolded files when the key is not > present. > > Note from ebiggers: > (These checks for the encryption key are still racy since they happen > too late, but apparently they worked well enough...) > > This bug made it impossible to delete encrypted+casefolded directories > without the encryption key, due to errors like: > > W : EXT4-fs warning (device vdc): __ext4fs_dirhash:270: inode #49202: comm Binder:378_4: Siphash requires key > > Repro steps in kvm-xfstests test appliance: > mkfs.ext4 -F -E encoding=utf8 -O encrypt /dev/vdc > mount /vdc > mkdir /vdc/dir > chattr +F /vdc/dir > keyid=$(head -c 64 /dev/zero | xfs_io -c add_enckey /vdc | awk '{print $NF}') > xfs_io -c "set_encpolicy $keyid" /vdc/dir > for i in `seq 1 100`; do > mkdir /vdc/dir/$i > done > xfs_io -c "rm_enckey $keyid" /vdc > rm -rf /vdc/dir # fails with the bug Looks fine, but can you please turn this reproducer into an xfstest? I'm also wondering if you've done any investigation into fixing ext4 to handle filenames properly like f2fs does, so that the above-mentioned race condition is eliminated. In particular, we should decide whether the user-supplied filename is a no-key name, and whether it needs casefolding or not, just once -- rather than separately for each directory entry compared in ext4_match(). - Eric
On Sat, May 22, 2021 at 12:41:32AM +0000, Daniel Rosenberg wrote: > commit 471fbbea7ff7 ("ext4: handle casefolding with encryption") is > missing a few checks for the encryption key which are needed to > support deleting enrypted casefolded files when the key is not > present. > > Note from ebiggers: > (These checks for the encryption key are still racy since they happen > too late, but apparently they worked well enough...) > > This bug made it impossible to delete encrypted+casefolded directories > without the encryption key, due to errors like: > > W : EXT4-fs warning (device vdc): __ext4fs_dirhash:270: inode #49202: comm Binder:378_4: Siphash requires key > > Repro steps in kvm-xfstests test appliance: > mkfs.ext4 -F -E encoding=utf8 -O encrypt /dev/vdc > mount /vdc > mkdir /vdc/dir > chattr +F /vdc/dir > keyid=$(head -c 64 /dev/zero | xfs_io -c add_enckey /vdc | awk '{print $NF}') > xfs_io -c "set_encpolicy $keyid" /vdc/dir > for i in `seq 1 100`; do > mkdir /vdc/dir/$i > done > xfs_io -c "rm_enckey $keyid" /vdc > rm -rf /vdc/dir # fails with the bug > > Fixes: 471fbbea7ff7 ("ext4: handle casefolding with encryption") > Signed-off-by: Daniel Rosenberg <drosen@google.com> Applied, thanks. - Ted
diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c index afb9d05a99ba..a4af26d4459a 100644 --- a/fs/ext4/namei.c +++ b/fs/ext4/namei.c @@ -1376,7 +1376,8 @@ int ext4_fname_setup_ci_filename(struct inode *dir, const struct qstr *iname, struct dx_hash_info *hinfo = &name->hinfo; int len; - if (!IS_CASEFOLDED(dir) || !dir->i_sb->s_encoding) { + if (!IS_CASEFOLDED(dir) || !dir->i_sb->s_encoding || + (IS_ENCRYPTED(dir) && !fscrypt_has_encryption_key(dir))) { cf_name->name = NULL; return 0; } @@ -1427,7 +1428,8 @@ static bool ext4_match(struct inode *parent, #endif #ifdef CONFIG_UNICODE - if (parent->i_sb->s_encoding && IS_CASEFOLDED(parent)) { + if (parent->i_sb->s_encoding && IS_CASEFOLDED(parent) && + (!IS_ENCRYPTED(parent) || fscrypt_has_encryption_key(parent))) { if (fname->cf_name.name) { struct qstr cf = {.name = fname->cf_name.name, .len = fname->cf_name.len};
commit 471fbbea7ff7 ("ext4: handle casefolding with encryption") is missing a few checks for the encryption key which are needed to support deleting enrypted casefolded files when the key is not present. Note from ebiggers: (These checks for the encryption key are still racy since they happen too late, but apparently they worked well enough...) This bug made it impossible to delete encrypted+casefolded directories without the encryption key, due to errors like: W : EXT4-fs warning (device vdc): __ext4fs_dirhash:270: inode #49202: comm Binder:378_4: Siphash requires key Repro steps in kvm-xfstests test appliance: mkfs.ext4 -F -E encoding=utf8 -O encrypt /dev/vdc mount /vdc mkdir /vdc/dir chattr +F /vdc/dir keyid=$(head -c 64 /dev/zero | xfs_io -c add_enckey /vdc | awk '{print $NF}') xfs_io -c "set_encpolicy $keyid" /vdc/dir for i in `seq 1 100`; do mkdir /vdc/dir/$i done xfs_io -c "rm_enckey $keyid" /vdc rm -rf /vdc/dir # fails with the bug Fixes: 471fbbea7ff7 ("ext4: handle casefolding with encryption") Signed-off-by: Daniel Rosenberg <drosen@google.com> --- fs/ext4/namei.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)