kernel/linux.git/fs/crypto, branch linux-6.0.y

fscrypt: fix keyring memory leak on mount failure

2022-11-10T17:17:30+00:00

commit ccd30a476f8e864732de220bd50e6f372f5ebcab upstream. Commit d7e7b9af104c ("fscrypt: stop using keyrings subsystem for fscrypt_master_key") moved the keyring destruction from __put_super() to generic_shutdown_super() so that the filesystem's block device(s) are still available. Unfortunately, this causes a memory leak in the case where a mount is attempted with the test_dummy_encryption mount option, but the mount fails after the option has already been processed. To fix this, attempt the keyring destruction in both places. Reported-by: syzbot+104c2a89561289cec13e@syzkaller.appspotmail.com Fixes: d7e7b9af104c ("fscrypt: stop using keyrings subsystem for fscrypt_master_key") Signed-off-by: Eric Biggers Reviewed-by: Christian Brauner (Microsoft) Link: https://lore.kernel.org/r/20221011213838.209879-1-ebiggers@kernel.org Signed-off-by: Greg Kroah-Hartman

fscrypt: stop using keyrings subsystem for fscrypt_master_key

2022-11-10T17:17:30+00:00

commit d7e7b9af104c7b389a0c21eb26532511bce4b510 upstream. The approach of fs/crypto/ internally managing the fscrypt_master_key structs as the payloads of "struct key" objects contained in a "struct key" keyring has outlived its usefulness. The original idea was to simplify the code by reusing code from the keyrings subsystem. However, several issues have arisen that can't easily be resolved: - When a master key struct is destroyed, blk_crypto_evict_key() must be called on any per-mode keys embedded in it. (This started being the case when inline encryption support was added.) Yet, the keyrings subsystem can arbitrarily delay the destruction of keys, even past the time the filesystem was unmounted. Therefore, currently there is no easy way to call blk_crypto_evict_key() when a master key is destroyed. Currently, this is worked around by holding an extra reference to the filesystem's request_queue(s). But it was overlooked that the request_queue reference is *not* guaranteed to pin the corresponding blk_crypto_profile too; for device-mapper devices that support inline crypto, it doesn't. This can cause a use-after-free. - When the last inode that was using an incompletely-removed master key is evicted, the master key removal is completed by removing the key struct from the keyring. Currently this is done via key_invalidate(). Yet, key_invalidate() takes the key semaphore. This can deadlock when called from the shrinker, since in fscrypt_ioctl_add_key(), memory is allocated with GFP_KERNEL under the same semaphore. - More generally, the fact that the keyrings subsystem can arbitrarily delay the destruction of keys (via garbage collection delay, or via random processes getting temporary key references) is undesirable, as it means we can't strictly guarantee that all secrets are ever wiped. - Doing the master key lookups via the keyrings subsystem results in the key_permission LSM hook being called. fscrypt doesn't want this, as all access control for encrypted files is designed to happen via the files themselves, like any other files. The workaround which SELinux users are using is to change their SELinux policy to grant key search access to all domains. This works, but it is an odd extra step that shouldn't really have to be done. The fix for all these issues is to change the implementation to what I should have done originally: don't use the keyrings subsystem to keep track of the filesystem's fscrypt_master_key structs. Instead, just store them in a regular kernel data structure, and rework the reference counting, locking, and lifetime accordingly. Retain support for RCU-mode key lookups by using a hash table. Replace fscrypt_sb_free() with fscrypt_sb_delete(), which releases the keys synchronously and runs a bit earlier during unmount, so that block devices are still available. A side effect of this patch is that neither the master keys themselves nor the filesystem keyrings will be listed in /proc/keys anymore. ("Master key users" and the master key users keyrings will still be listed.) However, this was mostly an implementation detail, and it was intended just for debugging purposes. I don't know of anyone using it. This patch does *not* change how "master key users" (->mk_users) works; that still uses the keyrings subsystem. That is still needed for key quotas, and changing that isn't necessary to solve the issues listed above. If we decide to change that too, it would be a separate patch. I've marked this as fixing the original commit that added the fscrypt keyring, but as noted above the most important issue that this patch fixes wasn't introduced until the addition of inline encryption support. Fixes: 22d94f493bfb ("fscrypt: add FS_IOC_ADD_ENCRYPTION_KEY ioctl") Signed-off-by: Eric Biggers Link: https://lore.kernel.org/r/20220901193208.138056-2-ebiggers@kernel.org Signed-off-by: Greg Kroah-Hartman

Merge tag 'ceph-for-5.20-rc1' of https://github.com/ceph/ceph-client

2022-08-11T19:41:07+00:00

Pull ceph updates from Ilya Dryomov: "We have a good pile of various fixes and cleanups from Xiubo, Jeff, Luis and others, almost exclusively in the filesystem. Several patches touch files outside of our normal purview to set the stage for bringing in Jeff's long awaited ceph+fscrypt series in the near future. All of them have appropriate acks and sat in linux-next for a while" * tag 'ceph-for-5.20-rc1' of https://github.com/ceph/ceph-client: (27 commits) libceph: clean up ceph_osdc_start_request prototype libceph: fix ceph_pagelist_reserve() comment typo ceph: remove useless check for the folio ceph: don't truncate file in atomic_open ceph: make f_bsize always equal to f_frsize ceph: flush the dirty caps immediatelly when quota is approaching libceph: print fsid and epoch with osd id libceph: check pointer before assigned to "c->rules[]" ceph: don't get the inline data for new creating files ceph: update the auth cap when the async create req is forwarded ceph: make change_auth_cap_ses a global symbol ceph: fix incorrect old_size length in ceph_mds_request_args ceph: switch back to testing for NULL folio->private in ceph_dirty_folio ceph: call netfs_subreq_terminated with was_async == false ceph: convert to generic_file_llseek ceph: fix the incorrect comment for the ceph_mds_caps struct ceph: don't leak snap_rwsem in handle_cap_grant ceph: prevent a client from exceeding the MDS maximum xattr size ceph: choose auth MDS for getxattr with the Xs caps ceph: add session already open notify support ...

fscrypt: add fscrypt_context_for_new_inode

2022-08-02T22:54:11+00:00

Most filesystems just call fscrypt_set_context on new inodes, which usually causes a setxattr. That's a bit late for ceph, which can send along a full set of attributes with the create request. Doing so allows it to avoid race windows that where the new inode could be seen by other clients without the crypto context attached. It also avoids the separate round trip to the server. Refactor the fscrypt code a bit to allow us to create a new crypto context, attach it to the inode, and write it to the buffer, but without calling set_context on it. ceph can later use this to marshal the context into the attributes we send along with the create request. Signed-off-by: Jeff Layton Reviewed-by: Xiubo Li Acked-by: Eric Biggers Signed-off-by: Ilya Dryomov

fscrypt: export fscrypt_fname_encrypt and fscrypt_fname_encrypted_size

2022-08-02T22:54:11+00:00

For ceph, we want to use our own scheme for handling filenames that are are longer than NAME_MAX after encryption and Base64 encoding. This allows us to have a consistent view of the encrypted filenames for clients that don't support fscrypt and clients that do but that don't have the key. Currently, fs/crypto only supports encrypting filenames using fscrypt_setup_filename, but that also handles encoding nokey names. Ceph can't use that because it handles nokey names in a different way. Export fscrypt_fname_encrypt. Rename fscrypt_fname_encrypted_size to __fscrypt_fname_encrypted_size and add a new wrapper called fscrypt_fname_encrypted_size that takes an inode argument rather than a pointer to a fscrypt_policy union. Signed-off-by: Jeff Layton Reviewed-by: Xiubo Li Acked-by: Eric Biggers Signed-off-by: Ilya Dryomov

fscrypt: Add HCTR2 support for filename encryption

2022-06-10T08:40:18+00:00

HCTR2 is a tweakable, length-preserving encryption mode that is intended for use on CPUs with dedicated crypto instructions. HCTR2 has the property that a bitflip in the plaintext changes the entire ciphertext. This property fixes a known weakness with filename encryption: when two filenames in the same directory share a prefix of >= 16 bytes, with AES-CTS-CBC their encrypted filenames share a common substring, leaking information. HCTR2 does not have this problem. More information on HCTR2 can be found here: "Length-preserving encryption with HCTR2": https://eprint.iacr.org/2021/1441.pdf Signed-off-by: Nathan Huckleberry Reviewed-by: Ard Biesheuvel Acked-by: Eric Biggers Signed-off-by: Herbert Xu

fscrypt: add new helper functions for test_dummy_encryption

2022-05-09T23:18:54+00:00

Unfortunately the design of fscrypt_set_test_dummy_encryption() doesn't work properly for the new mount API, as it combines too many steps into one function: - Parse the argument to test_dummy_encryption - Check the setting against the filesystem instance - Apply the setting to the filesystem instance The new mount API has split these into separate steps. ext4 partially worked around this by duplicating some of the logic, but it still had some bugs. To address this, add some new helper functions that split up the steps of fscrypt_set_test_dummy_encryption(): - fscrypt_parse_test_dummy_encryption() - fscrypt_dummy_policies_equal() - fscrypt_add_test_dummy_key() While we're add it, also add a function fscrypt_is_dummy_policy_set() which will be useful to avoid some #ifdef's. Signed-off-by: Eric Biggers Link: https://lore.kernel.org/r/20220501050857.538984-5-ebiggers@kernel.org

fscrypt: factor out fscrypt_policy_to_key_spec()

2022-05-09T23:18:54+00:00

Factor out a function that builds the fscrypt_key_specifier for an fscrypt_policy. Before this was only needed when finding the key for a file, but now it will also be needed for test_dummy_encryption support. Signed-off-by: Eric Biggers Link: https://lore.kernel.org/r/20220501050857.538984-4-ebiggers@kernel.org

fscrypt: log when starting to use inline encryption

2022-04-14T05:35:25+00:00

When inline encryption is used, the usual message "fscrypt: AES-256-XTS using implementation " doesn't appear in the kernel log. Add a similar message for the blk-crypto case that indicates that inline encryption was used, and whether blk-crypto-fallback was used or not. This can be useful for debugging performance problems. Signed-off-by: Eric Biggers Link: https://lore.kernel.org/r/20220414053415.158986-1-ebiggers@kernel.org

fscrypt: split up FS_CRYPTO_BLOCK_SIZE

2022-04-13T22:03:09+00:00

FS_CRYPTO_BLOCK_SIZE is neither the filesystem block size nor the granularity of encryption. Rather, it defines two logically separate constraints that both arise from the block size of the AES cipher: - The alignment required for the lengths of file contents blocks - The minimum input/output length for the filenames encryption modes Since there are way too many things called the "block size", and the connection with the AES block size is not easily understood, split FS_CRYPTO_BLOCK_SIZE into two constants FSCRYPT_CONTENTS_ALIGNMENT and FSCRYPT_FNAME_MIN_MSG_LEN that more clearly describe what they are. Signed-off-by: Eric Biggers Link: https://lore.kernel.org/r/20220405010914.18519-1-ebiggers@kernel.org