On Tue, Nov 17, 2020 at 11:56:04PM -0800, Eric Biggers wrote: > This series fixes a longstanding race condition where a duplicate > filename can be created in an encrypted directory if a syscall that > creates a new filename (e.g. open() or mkdir()) races with the > directory's encryption key being added. > > To close this race, we need to prevent creating files if the dentry is > still marked as a no-key name. I.e. we need to fail the ->create() (or > other operation that creates a new filename) if the key wasn't available > when doing the dentry lookup earlier in the syscall, even if the key was > concurrently added between the dentry lookup and ->create(). > > See patch 1 for a more detailed explanation. > > Patch 1 introduces a helper function required for the fix. Patches 2-4 > fix the bug on ext4, f2fs, and ubifs. Patch 5 is a cleanup. > > This fixes xfstest generic/595 on ubifs, but that test was hitting this > bug only accidentally. I've also written a new xfstest which reproduces > this bug on both ext4 and ubifs. > > Eric Biggers (5): > fscrypt: add fscrypt_is_nokey_name() > ext4: prevent creating duplicate encrypted filenames > f2fs: prevent creating duplicate encrypted filenames > ubifs: prevent creating duplicate encrypted filenames > fscrypt: remove unnecessary calls to fscrypt_require_key() > > fs/crypto/hooks.c | 31 +++++++++++-------------------- > fs/ext4/namei.c | 3 +++ > fs/f2fs/f2fs.h | 2 ++ > fs/ubifs/dir.c | 17 +++++++++++++---- > include/linux/fscrypt.h | 37 +++++++++++++++++++++++++++++++++++-- > 5 files changed, 64 insertions(+), 26 deletions(-) > > > base-commit: 3ceb6543e9cf6ed87cc1fbc6f23ca2db903564cd All applied to fscrypt.git#master for 5.11. I'd still appreciate acks for ext4, f2fs, and ubifs though. - Eric
