IV_INO_LBLK_32 policies introduced the possibility that logically
contiguous data blocks might not have contiguous DUNs (because of
potential DUN wraparound). As such, whenever a page is merged into a
bio, fscrypt_mergeable_bio() must be called to check DUN contiguity.
Further, fscrypt inline encryption does not handle the case when the DUN
wraps around within a page (which can happen when the data unit size !=
PAGE_SIZE). For now, we handle that by disallowing inline encryption
with IV_INO_LBLK_32 policies when the data unit size != PAGE_SIZE (and
dropping the now redundant check for this in fscrypt_dio_supported()).
Bug: 144046242
Change-Id: I9cb414fcc284b197b9d3d1b9643029c6b875df5a
Signed-off-by: Satya Tangirala <satyat@google.com>
This reverts commit 98261f39e992543a404353ba2d8f36cb739f329f
because it was only needed for sdcardfs, which has now been removed.
Bug: 157700134
Bug: 142275883
Change-Id: Iaf22521ef47d48ce9c9c0604a8b2412e3b8c1faa
Signed-off-by: Eric Biggers <ebiggers@google.com>
The eMMC inline crypto standard will only specify 32 DUN bits (a.k.a. IV
bits), unlike UFS's 64. IV_INO_LBLK_64 is therefore not applicable, but
an encryption format which uses one key per policy and permits the
moving of encrypted file contents (as f2fs's garbage collector requires)
is still desirable.
To support such hardware, add a new encryption format IV_INO_LBLK_32
that makes the best use of the 32 bits: the IV is set to
'SipHash-2-4(inode_number) + file_logical_block_number mod 2^32', where
the SipHash key is derived from the fscrypt master key. We hash only
the inode number and not also the block number, because we need to
maintain contiguity of DUNs to merge bios.
Unlike with IV_INO_LBLK_64, with this format IV reuse is possible; this
is unavoidable given the size of the DUN. This means this format should
only be used where the requirements of the first paragraph apply.
However, the hash spreads out the IVs in the whole usable range, and the
use of a keyed hash makes it difficult for an attacker to determine
which files use which IVs.
Besides the above differences, this flag works like IV_INO_LBLK_64 in
that on ext4 it is only allowed if the stable_inodes feature has been
enabled to prevent inode numbers and the filesystem UUID from changing.
Link: https://lore.kernel.org/r/20200515204141.251098-1-ebiggers@kernel.org
Reviewed-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Paul Crowley <paulcrowley@google.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Since v1 encryption policies are deprecated, make test_dummy_encryption
test v2 policies by default.
Note that this causes ext4/023 and ext4/028 to start failing due to
known bugs in those tests (see previous commit).
Link: https://lore.kernel.org/r/20200512233251.118314-5-ebiggers@kernel.org
Reviewed-by: Jaegeuk Kim <jaegeuk@kernel.org>
Reviewed-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Eric Biggers <ebiggers@google.com>
v1 encryption policies are deprecated in favor of v2, and some new
features (e.g. encryption+casefolding) are only being added for v2.
Therefore, the "test_dummy_encryption" mount option (which is used for
encryption I/O testing with xfstests) needs to support v2 policies.
To do this, extend its syntax to be "test_dummy_encryption=v1" or
"test_dummy_encryption=v2". The existing "test_dummy_encryption" (no
argument) also continues to be accepted, to specify the default setting
-- currently v1, but the next patch changes it to v2.
To cleanly support both v1 and v2 while also making it easy to support
specifying other encryption settings in the future (say, accepting
"$contents_mode:$filenames_mode:v2"), make ext4 and f2fs maintain a
pointer to the dummy fscrypt_context rather than using mount flags.
To avoid concurrency issues, don't allow test_dummy_encryption to be set
or changed during a remount. (The former restriction is new, but
xfstests doesn't run into it, so no one should notice.)
Tested with 'gce-xfstests -c {ext4,f2fs}/encrypt -g auto'. On ext4,
there are two regressions, both of which are test bugs: ext4/023 and
ext4/028 fail because they set an xattr and expect it to be stored
inline, but the increase in size of the fscrypt_context from
24 to 40 bytes causes this xattr to be spilled into an external block.
Link: https://lore.kernel.org/r/20200512233251.118314-4-ebiggers@kernel.org
Acked-by: Jaegeuk Kim <jaegeuk@kernel.org>
Reviewed-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Currently, the test_dummy_encryption mount option (which is used for
encryption I/O testing with xfstests) uses v1 encryption policies, and
it relies on userspace inserting a test key into the session keyring.
We need test_dummy_encryption to support v2 encryption policies too.
Requiring userspace to add the test key doesn't work well with v2
policies, since v2 policies only support the filesystem keyring (not the
session keyring), and keys in the filesystem keyring are lost when the
filesystem is unmounted. Hooking all test code that unmounts and
re-mounts the filesystem would be difficult.
Instead, let's make the filesystem automatically add the test key to its
keyring when test_dummy_encryption is enabled.
That puts the responsibility for choosing the test key on the kernel.
We could just hard-code a key. But out of paranoia, let's first try
using a per-boot random key, to prevent this code from being misused.
A per-boot key will work as long as no one expects dummy-encrypted files
to remain accessible after a reboot. (gce-xfstests doesn't.)
Therefore, this patch adds a function fscrypt_add_test_dummy_key() which
implements the above. The next patch will use it.
Link: https://lore.kernel.org/r/20200512233251.118314-3-ebiggers@kernel.org
Reviewed-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Remove the unnecessary 'extern' keywords from function declarations.
This makes it so that we don't have a mix of both styles, so it won't be
ambiguous what to use in new fscrypt patches. This also makes the code
shorter and matches the 'checkpatch --strict' expectation.
Link: https://lore.kernel.org/r/20200511191358.53096-4-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
Fix all kerneldoc warnings in fs/crypto/ and include/linux/fscrypt.h.
Most of these were due to missing documentation for function parameters.
Detected with:
scripts/kernel-doc -v -none fs/crypto/*.{c,h} include/linux/fscrypt.h
This cleanup makes it possible to check new patches for kerneldoc
warnings without having to filter out all the existing ones.
For consistency, also adjust some function "brief descriptions" to
include the parentheses and to wrap at 80 characters. (The latter
matches the checkpatch expectation.)
Link: https://lore.kernel.org/r/20200511191358.53096-2-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
With the existing fscrypt IV generation methods, each file's data blocks
have contiguous DUNs. Therefore the direct I/O code "just worked"
because it only submits logically contiguous bios. But with
IV_INO_LBLK_32, the direct I/O code breaks because the DUN can wrap from
0xffffffff to 0. We can't submit bios across such boundaries.
This is especially difficult to handle when block_size != PAGE_SIZE,
since in that case the DUN can wrap in the middle of a page. Punt on
this case for now and just handle block_size == PAGE_SIZE.
Add and use a new function fscrypt_dio_supported() to check whether a
direct I/O request is unsupported due to encryption constraints.
Then, update fs/direct-io.c (used by f2fs, and by ext4 in kernel v5.4
and earlier) and fs/iomap/direct-io.c (used by ext4 in kernel v5.5 and
later) to avoid submitting I/O across a DUN discontinuity.
(This is needed in ACK now because ACK already supports direct I/O with
inline crypto. I'll be sending this upstream along with the encrypted
direct I/O support itself once its prerequisites are closer to landing.)
(cherry picked from android-mainline commit
8d6c90c9d68b985fa809626d12f8c9aff3c9dcb1)
Conflicts:
fs/ext4/file.c
fs/iomap/direct-io.c
(Dropped the iomap changes because in kernel v5.4 and earlier,
ext4 doesn't use iomap for direct I/O)
Test: For now, just manually tested direct I/O on ext4 and f2fs in the
DUN discontinuity case.
Bug: 144046242
Change-Id: I0c0b0b20a73ade35c3660cc6f9c09d49d3853ba5
Signed-off-by: Eric Biggers <ebiggers@google.com>
The eMMC inline crypto standard will only specify 32 DUN bits (a.k.a. IV
bits), unlike UFS's 64. IV_INO_LBLK_64 is therefore not applicable, but
an encryption format which uses one key per policy and permits the
moving of encrypted file contents (as f2fs's garbage collector requires)
is still desirable.
To support such hardware, add a new encryption format IV_INO_LBLK_32
that makes the best use of the 32 bits: the IV is set to
'SipHash-2-4(inode_number) + file_logical_block_number mod 2^32', where
the SipHash key is derived from the fscrypt master key. We hash only
the inode number and not also the block number, because we need to
maintain contiguity of DUNs to merge bios.
Unlike with IV_INO_LBLK_64, with this format IV reuse is possible; this
is unavoidable given the size of the DUN. This means this format should
only be used where the requirements of the first paragraph apply.
However, the hash spreads out the IVs in the whole usable range, and the
use of a keyed hash makes it difficult for an attacker to determine
which files use which IVs.
Besides the above differences, this flag works like IV_INO_LBLK_64 in
that on ext4 it is only allowed if the stable_inodes feature has been
enabled to prevent inode numbers and the filesystem UUID from changing.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Link: https://lore.kernel.org/r/20200515204141.251098-1-ebiggers@kernel.org
(Resolved conflicts with inline encryption support. Besides the
necessary "straightforward" merge resolutions, also made
fscrypt_get_dun_bytes() aware of IV_INO_LBLK_32 and made IV_INO_LBLK_32
usable with wrapped keys.)
Test: 'atest vts_kernel_encryption_test' on Cuttlefish with
the IV_INO_LBLK_32 test added (http://aosp/1315024).
Also tested enabling this in the fstab for Cuttlefish
(using http://aosp/1315886).
Also ran 'kvm-xfstests -c ext4,f2fs -g encrypt', including my
work-in-progress xfstest for IV_INO_LBLK_32.
Bug: 144046242
Change-Id: I57df71d502bde0475efc906a0812102063ff2f2a
Signed-off-by: Eric Biggers <ebiggers@google.com>
Make fscrypt set dun_bytes to only what it actually needs, so that it
can make use of inline crypto hardware in more cases.
Bug: 144046242
Bug: 153512828
Change-Id: I36f90ea6b64ef51a9d58ffb069d2cba74965c239
Signed-off-by: Eric Biggers <ebiggers@google.com>
Backport a fix from the v7 inline crypto patchset which ensures that the
block layer knows the number of DUN bytes the inline encryption hardware
supports, so that hardware isn't used when it shouldn't be.
(This unfortunately means introducing some increasing long argument
lists; this was all already fixed up in later versions of the patchset.)
To avoid breaking the KMI for drivers, don't add a dun_bytes argument to
keyslot_manager_create() but rather allow drivers to call
keyslot_manager_set_max_dun_bytes() to override the default. Also,
don't add dun_bytes as a new field in 'struct blk_crypto_key' but rather
pack it into the existing 'hash' field which is for block layer use.
Bug: 144046242
Bug: 153512828
Change-Id: I285f36557fb3eafc5f2f64727ef1740938b59dd7
Signed-off-by: Eric Biggers <ebiggers@google.com>
In commit d16d9c0046eb ("FROMLIST: fscrypt: Have filesystems handle their d_ops")
a new symbol was exported, but it should have been set as a _GPL symbol.
Fix this up by properly.
Bug: 138322712
Cc: Daniel Rosenberg <drosen@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: I51e23761d3c898a0bf612048c8febd98a0817ae3
Add an ioctl FS_IOC_GET_ENCRYPTION_NONCE which retrieves the nonce from
an encrypted file or directory. The nonce is the 16-byte random value
stored in the inode's encryption xattr. It is normally used together
with the master key to derive the inode's actual encryption key.
The nonces are needed by automated tests that verify the correctness of
the ciphertext on-disk. Except for the IV_INO_LBLK_64 case, there's no
way to replicate a file's ciphertext without knowing that file's nonce.
The nonces aren't secret, and the existing ciphertext verification tests
in xfstests retrieve them from disk using debugfs or dump.f2fs. But in
environments that lack these debugging tools, getting the nonces by
manually parsing the filesystem structure would be very hard.
To make this important type of testing much easier, let's just add an
ioctl that retrieves the nonce.
Link: https://lore.kernel.org/r/20200314205052.93294-2-ebiggers@kernel.org
Reviewed-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Eric Biggers <ebiggers@google.com>
When the filesystem is mounted with '-o inlinecrypt', make fscrypt fall
back to filesystem-layer crypto when inline crypto won't work, e.g. due
to the hardware not supporting the encryption algorithm.
When blk-crypto-fallback is disabled, this fixes '-o inlinecrypt' to not
break any fscrypt policies that would otherwise work.
This is needed for VtsKernelEncryptionTest to pass on some devices.
Bug: 137270441
Bug: 151100202
Test: 'atest vts_kernel_encryption_test' on Pixel 4 with the
inline crypto patches backported, and also on Cuttlefish.
Change-Id: I3e730df4608efb12d7126d1a85faddcccb566764
Signed-off-by: Eric Biggers <ebiggers@google.com>
We need a way to tell which type of keys the inline crypto hardware
supports (standard, wrapped, or both), so that fallbacks can be used
when needed (either blk-crypto-fallback, or fscrypt fs-layer crypto).
We can't simply assume that
keyslot_mgmt_ll_ops::derive_raw_secret == NULL
means only standard keys are supported and that
keyslot_mgmt_ll_ops::derive_raw_secret != NULL
means that only wrapped keys are supported, because device-mapper
devices always implement this method. Also, hardware might support both
types of keys.
Therefore, add a field keyslot_manager::features which contains a
bitmask of flags which indicate the supported types of keys. Drivers
will need to fill this in. This patch makes the UFS standard crypto
code set BLK_CRYPTO_FEATURE_STANDARD_KEYS, but UFS variant drivers may
need to set BLK_CRYPTO_FEATURE_WRAPPED_KEYS instead.
Then, make keyslot_manager_crypto_mode_supported() take the key type
into account.
Bug: 137270441
Bug: 151100202
Test: 'atest vts_kernel_encryption_test' on Pixel 4 with the
inline crypto patches backported, and also on Cuttlefish.
Change-Id: Ied846c2767c1fd2f438792dcfd3649157e68b005
Signed-off-by: Eric Biggers <ebiggers@google.com>
Add an ioctl FS_IOC_GET_ENCRYPTION_NONCE which retrieves the nonce from
an encrypted file or directory. The nonce is the 16-byte random value
stored in the inode's encryption xattr. It is normally used together
with the master key to derive the inode's actual encryption key.
The nonces are needed by automated tests that verify the correctness of
the ciphertext on-disk. Except for the IV_INO_LBLK_64 case, there's no
way to replicate a file's ciphertext without knowing that file's nonce.
The nonces aren't secret, and the existing ciphertext verification tests
in xfstests retrieve them from disk using debugfs or dump.f2fs. But in
environments that lack these debugging tools, getting the nonces by
manually parsing the filesystem structure would be very hard.
To make this important type of testing much easier, let's just add an
ioctl that retrieves the nonce.
Link: https://lore.kernel.org/r/20200314205052.93294-2-ebiggers@kernel.org
Reviewed-by: Theodore Ts'o <tytso@mit.edu>
(cherry picked from commit e98ad464750c0894bc560d10503dae8ff90ccdac)
Bug: 151100202
Change-Id: Ieef2c57b9257ae38eb2e5c1a018ca6f325bb62dd
Signed-off-by: Eric Biggers <ebiggers@google.com>
After FS_IOC_REMOVE_ENCRYPTION_KEY removes a key, it syncs the
filesystem and tries to get and put all inodes that were unlocked by the
key so that unused inodes get evicted via fscrypt_drop_inode().
Normally, the inodes are all clean due to the sync.
However, after the filesystem is sync'ed, userspace can modify and close
one of the files. (Userspace is *supposed* to close the files before
removing the key. But it doesn't always happen, and the kernel can't
assume it.) This causes the inode to be dirtied and have i_count == 0.
Then, fscrypt_drop_inode() failed to consider this case and indicated
that the inode can be dropped, causing the write to be lost.
On f2fs, other problems such as a filesystem freeze could occur due to
the inode being freed while still on f2fs's dirty inode list.
Fix this bug by making fscrypt_drop_inode() only drop clean inodes.
I've written an xfstest which detects this bug on ext4, f2fs, and ubifs.
Fixes: b1c0ec3599f4 ("fscrypt: add FS_IOC_REMOVE_ENCRYPTION_KEY ioctl")
Cc: <stable@vger.kernel.org> # v5.4+
Link: https://lore.kernel.org/r/20200305084138.653498-1-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
After FS_IOC_REMOVE_ENCRYPTION_KEY removes a key, it syncs the
filesystem and tries to get and put all inodes that were unlocked by the
key so that unused inodes get evicted via fscrypt_drop_inode().
Normally, the inodes are all clean due to the sync.
However, after the filesystem is sync'ed, userspace can modify and close
one of the files. (Userspace is *supposed* to close the files before
removing the key. But it doesn't always happen, and the kernel can't
assume it.) This causes the inode to be dirtied and have i_count == 0.
Then, fscrypt_drop_inode() failed to consider this case and indicated
that the inode can be dropped, causing the write to be lost.
On f2fs, other problems such as a filesystem freeze could occur due to
the inode being freed while still on f2fs's dirty inode list.
Fix this bug by making fscrypt_drop_inode() only drop clean inodes.
I've written an xfstest which detects this bug on ext4, f2fs, and ubifs.
Fixes: b1c0ec3599f4 ("fscrypt: add FS_IOC_REMOVE_ENCRYPTION_KEY ioctl")
Cc: <stable@vger.kernel.org> # v5.4+
Link: https://lore.kernel.org/r/20200305084138.653498-1-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
(cherry picked from commit 2b4eae95c7361e0a147b838715c8baa1380a428f)
Bug: 150589360
Test: kvm-xfstests -c ext4,f2fs -g encrypt
Change-Id: Ia32db980c2fffb68caeaf9f38e5cfbe781b45011
Signed-off-by: Eric Biggers <ebiggers@google.com>
This shifts the responsibility of setting up dentry operations from
fscrypt to the individual filesystems, allowing them to have their own
operations while still setting fscrypt's d_revalidate as appropriate.
Also added helper function to libfs to unify ext4 and f2fs
implementations.
Signed-off-by: Daniel Rosenberg <drosen@google.com>
Test: Boots, /data/media is case insensitive
Bug: 138322712
Link: https://lore.kernel.org/linux-f2fs-devel/20200208013552.241832-1-drosen@google.com/T/#t
Change-Id: Iaf77f8c5961ecf22e22478701ab0b7fe2025225d
blk-crypto-fallback does not support wrapped keys, hence
prevent falling back when program_key fails. Add 'is_hw_wrapped'
flag to blk-crypto-key to mention if the key is wrapped
when the key is initialized.
Bug: 147209885
Test: Validate FBE, simulate a failure in the underlying blk
device and ensure the call fails without falling back
to blk-crypto-fallback.
Change-Id: I8bc301ca1ac9e55ba6ab622e8325486916b45c56
Signed-off-by: Barani Muthukumaran <bmuthuku@codeaurora.org>
* aosp/upstream-f2fs-stable-linux-4.19.y:
fs-verity: use u64_to_user_ptr()
fs-verity: use mempool for hash requests
fs-verity: implement readahead of Merkle tree pages
fs-verity: implement readahead for FS_IOC_ENABLE_VERITY
fscrypt: improve format of no-key names
ubifs: allow both hash and disk name to be provided in no-key names
ubifs: don't trigger assertion on invalid no-key filename
fscrypt: clarify what is meant by a per-file key
fscrypt: derive dirhash key for casefolded directories
fscrypt: don't allow v1 policies with casefolding
fscrypt: add "fscrypt_" prefix to fname_encrypt()
fscrypt: don't print name of busy file when removing key
fscrypt: document gfp_flags for bounce page allocation
fscrypt: optimize fscrypt_zeroout_range()
fscrypt: remove redundant bi_status check
fscrypt: Allow modular crypto algorithms
fscrypt: include <linux/ioctl.h> in UAPI header
fscrypt: don't check for ENOKEY from fscrypt_get_encryption_info()
fscrypt: remove fscrypt_is_direct_key_policy()
fscrypt: move fscrypt_valid_enc_modes() to policy.c
fscrypt: check for appropriate use of DIRECT_KEY flag earlier
fscrypt: split up fscrypt_supported_policy() by policy version
fscrypt: introduce fscrypt_needs_contents_encryption()
fscrypt: move fscrypt_d_revalidate() to fname.c
fscrypt: constify inode parameter to filename encryption functions
fscrypt: constify struct fscrypt_hkdf parameter to fscrypt_hkdf_expand()
fscrypt: verify that the crypto_skcipher has the correct ivsize
fscrypt: use crypto_skcipher_driver_name()
fscrypt: support passing a keyring key to FS_IOC_ADD_ENCRYPTION_KEY
keys: Export lookup_user_key to external users
Conflicts:
fs/crypto/Kconfig
fs/crypto/bio.c
fs/crypto/fname.c
fs/crypto/fscrypt_private.h
fs/crypto/keyring.c
fs/crypto/keysetup.c
fs/ubifs/dir.c
include/uapi/linux/fscrypt.h
Resolved the conflicts as per the corresponding android-mainline change,
Ib1e6b9eda8fb5dcfc6bdc8fa89d93f72b088c5f6.
Bug: 148667616
Change-Id: I5f8b846f0cd4d5403d8c61b9e12acb4581fac6f7
Signed-off-by: Eric Biggers <ebiggers@google.com>
When an encrypted directory is listed without the key, the filesystem
must show "no-key names" that uniquely identify directory entries, are
at most 255 (NAME_MAX) bytes long, and don't contain '/' or '\0'.
Currently, for short names the no-key name is the base64 encoding of the
ciphertext filename, while for long names it's the base64 encoding of
the ciphertext filename's dirhash and second-to-last 16-byte block.
This format has the following problems:
- Since it doesn't always include the dirhash, it's incompatible with
directories that will use a secret-keyed dirhash over the plaintext
filenames. In this case, the dirhash won't be computable from the
ciphertext name without the key, so it instead must be retrieved from
the directory entry and always included in the no-key name.
Casefolded encrypted directories will use this type of dirhash.
- It's ambiguous: it's possible to craft two filenames that map to the
same no-key name, since the method used to abbreviate long filenames
doesn't use a proper cryptographic hash function.
Solve both these problems by switching to a new no-key name format that
is the base64 encoding of a variable-length structure that contains the
dirhash, up to 149 bytes of the ciphertext filename, and (if any bytes
remain) the SHA-256 of the remaining bytes of the ciphertext filename.
This ensures that each no-key name contains everything needed to find
the directory entry again, contains only legal characters, doesn't
exceed NAME_MAX, is unambiguous unless there's a SHA-256 collision, and
that we only take the performance hit of SHA-256 on very long filenames.
Note: this change does *not* address the existing issue where users can
modify the 'dirhash' part of a no-key name and the filesystem may still
accept the name.
Signed-off-by: Daniel Rosenberg <drosen@google.com>
[EB: improved comments and commit message, fixed checking return value
of base64_decode(), check for SHA-256 error, continue to set disk_name
for short names to keep matching simpler, and many other cleanups]
Link: https://lore.kernel.org/r/20200120223201.241390-7-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
Now that there's sometimes a second type of per-file key (the dirhash
key), clarify some function names, macros, and documentation that
specifically deal with per-file *encryption* keys.
Link: https://lore.kernel.org/r/20200120223201.241390-4-ebiggers@kernel.org
Reviewed-by: Daniel Rosenberg <drosen@google.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
When we allow indexed directories to use both encryption and
casefolding, for the dirhash we can't just hash the ciphertext filenames
that are stored on-disk (as is done currently) because the dirhash must
be case insensitive, but the stored names are case-preserving. Nor can
we hash the plaintext names with an unkeyed hash (or a hash keyed with a
value stored on-disk like ext4's s_hash_seed), since that would leak
information about the names that encryption is meant to protect.
Instead, if we can accept a dirhash that's only computable when the
fscrypt key is available, we can hash the plaintext names with a keyed
hash using a secret key derived from the directory's fscrypt master key.
We'll use SipHash-2-4 for this purpose.
Prepare for this by deriving a SipHash key for each casefolded encrypted
directory. Make sure to handle deriving the key not only when setting
up the directory's fscrypt_info, but also in the case where the casefold
flag is enabled after the fscrypt_info was already set up. (We could
just always derive the key regardless of casefolding, but that would
introduce unnecessary overhead for people not using casefolding.)
Signed-off-by: Daniel Rosenberg <drosen@google.com>
[EB: improved commit message, updated fscrypt.rst, squashed with change
that avoids unnecessarily deriving the key, and many other cleanups]
Link: https://lore.kernel.org/r/20200120223201.241390-3-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
Casefolded encrypted directories will use a new dirhash method that
requires a secret key. If the directory uses a v2 encryption policy,
it's easy to derive this key from the master key using HKDF. However,
v1 encryption policies don't provide a way to derive additional keys.
Therefore, don't allow casefolding on directories that use a v1 policy.
Specifically, make it so that trying to enable casefolding on a
directory that has a v1 policy fails, trying to set a v1 policy on a
casefolded directory fails, and trying to open a casefolded directory
that has a v1 policy (if one somehow exists on-disk) fails.
Signed-off-by: Daniel Rosenberg <drosen@google.com>
[EB: improved commit message, updated fscrypt.rst, and other cleanups]
Link: https://lore.kernel.org/r/20200120223201.241390-2-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
fname_encrypt() is a global function, due to being used in both fname.c
and hooks.c. So it should be prefixed with "fscrypt_", like all the
other global functions in fs/crypto/.
Link: https://lore.kernel.org/r/20200120071736.45915-1-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
When an encryption key can't be fully removed due to file(s) protected
by it still being in-use, we shouldn't really print the path to one of
these files to the kernel log, since parts of this path are likely to be
encrypted on-disk, and (depending on how the system is set up) the
confidentiality of this path might be lost by printing it to the log.
This is a trade-off: a single file path often doesn't matter at all,
especially if it's a directory; the kernel log might still be protected
in some way; and I had originally hoped that any "inode(s) still busy"
bugs (which are security weaknesses in their own right) would be quickly
fixed and that to do so it would be super helpful to always know the
file path and not have to run 'find dir -inum $inum' after the fact.
But in practice, these bugs can be hard to fix (e.g. due to asynchronous
process killing that is difficult to eliminate, for performance
reasons), and also not tied to specific files, so knowing a file path
doesn't necessarily help.
So to be safe, for now let's just show the inode number, not the path.
If someone really wants to know a path they can use 'find -inum'.
Fixes: b1c0ec3599f4 ("fscrypt: add FS_IOC_REMOVE_ENCRYPTION_KEY ioctl")
Cc: <stable@vger.kernel.org> # v5.4+
Link: https://lore.kernel.org/r/20200120060732.390362-1-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
Document that fscrypt_encrypt_pagecache_blocks() allocates the bounce
page from a mempool, and document what this means for the @gfp_flags
argument.
Link: https://lore.kernel.org/r/20191231181026.47400-1-ebiggers@kernel.org
Reviewed-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Currently fscrypt_zeroout_range() issues and waits on a bio for each
block it writes, which makes it very slow.
Optimize it to write up to 16 pages at a time instead.
Also add a function comment, and improve reliability by allowing the
allocations of the bio and the first ciphertext page to wait on the
corresponding mempools.
Link: https://lore.kernel.org/r/20191226160813.53182-1-ebiggers@kernel.org
Reviewed-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Eric Biggers <ebiggers@google.com>
The commit 643fa9612bf1 ("fscrypt: remove filesystem specific
build config option") removed modular support for fs/crypto. This
causes the Crypto API to be built-in whenever fscrypt is enabled.
This makes it very difficult for me to test modular builds of
the Crypto API without disabling fscrypt which is a pain.
As fscrypt is still evolving and it's developing new ties with the
fs layer, it's hard to build it as a module for now.
However, the actual algorithms are not required until a filesystem
is mounted. Therefore we can allow them to be built as modules.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Link: https://lore.kernel.org/r/20191227024700.7vrzuux32uyfdgum@gondor.apana.org.au
Signed-off-by: Eric Biggers <ebiggers@google.com>
fscrypt_valid_enc_modes() is only used by policy.c, so move it to there.
Also adjust the order of the checks to be more natural, matching the
numerical order of the constants and also keeping AES-256 (the
recommended default) first in the list.
No change in behavior.
Link: https://lore.kernel.org/r/20191209211829.239800-4-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
FSCRYPT_POLICY_FLAG_DIRECT_KEY is currently only allowed with Adiantum
encryption. But FS_IOC_SET_ENCRYPTION_POLICY allowed it in combination
with other encryption modes, and an error wasn't reported until later
when the encrypted directory was actually used.
Fix it to report the error earlier by validating the correct use of the
DIRECT_KEY flag in fscrypt_supported_policy(), similar to how we
validate the IV_INO_LBLK_64 flag.
Link: https://lore.kernel.org/r/20191209211829.239800-3-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
Make fscrypt_supported_policy() call new functions
fscrypt_supported_v1_policy() and fscrypt_supported_v2_policy(), to
reduce the indentation level and make the code easier to read.
Also adjust the function comment to mention that whether the encryption
policy is supported can also depend on the inode.
No change in behavior.
Link: https://lore.kernel.org/r/20191209211829.239800-2-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
fscrypt_d_revalidate() and fscrypt_d_ops really belong in fname.c, since
they're specific to filenames encryption. crypto.c is for contents
encryption and general fs/crypto/ initialization and utilities.
Link: https://lore.kernel.org/r/20191209204359.228544-1-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
Constify the struct fscrypt_hkdf parameter to fscrypt_hkdf_expand().
This makes it clearer that struct fscrypt_hkdf contains the key only,
not any per-request state.
Link: https://lore.kernel.org/r/20191209204054.227736-1-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
As a sanity check, verify that the allocated crypto_skcipher actually
has the ivsize that fscrypt is assuming it has. This will always be the
case unless there's a bug. But if there ever is such a bug (e.g. like
there was in earlier versions of the ESSIV conversion patch [1]) it's
preferable for it to be immediately obvious, and not rely on the
ciphertext verification tests failing due to uninitialized IV bytes.
[1] https://lkml.kernel.org/linux-crypto/20190702215517.GA69157@gmail.com/
Link: https://lore.kernel.org/r/20191209203918.225691-1-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
Crypto API users shouldn't really be accessing struct skcipher_alg
directly. <crypto/skcipher.h> already has a function
crypto_skcipher_driver_name(), so use that instead.
No change in behavior.
Link: https://lore.kernel.org/r/20191209203810.225302-1-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
Extend the FS_IOC_ADD_ENCRYPTION_KEY ioctl to allow the raw key to be
specified by a Linux keyring key, rather than specified directly.
This is useful because fscrypt keys belong to a particular filesystem
instance, so they are destroyed when that filesystem is unmounted.
Usually this is desired. But in some cases, userspace may need to
unmount and re-mount the filesystem while keeping the keys, e.g. during
a system update. This requires keeping the keys somewhere else too.
The keys could be kept in memory in a userspace daemon. But depending
on the security architecture and assumptions, it can be preferable to
keep them only in kernel memory, where they are unreadable by userspace.
We also can't solve this by going back to the original fscrypt API
(where for each file, the master key was looked up in the process's
keyring hierarchy) because that caused lots of problems of its own.
Therefore, add the ability for FS_IOC_ADD_ENCRYPTION_KEY to accept a
Linux keyring key. This solves the problem by allowing userspace to (if
needed) save the keys securely in a Linux keyring for re-provisioning,
while still using the new fscrypt key management ioctls.
This is analogous to how dm-crypt accepts a Linux keyring key, but the
key is then stored internally in the dm-crypt data structures rather
than being looked up again each time the dm-crypt device is accessed.
Use a custom key type "fscrypt-provisioning" rather than one of the
existing key types such as "logon". This is strongly desired because it
enforces that these keys are only usable for a particular purpose: for
fscrypt as input to a particular KDF. Otherwise, the keys could also be
passed to any kernel API that accepts a "logon" key with any service
prefix, e.g. dm-crypt, UBIFS, or (recently proposed) AF_ALG. This would
risk leaking information about the raw key despite it ostensibly being
unreadable. Of course, this mistake has already been made for multiple
kernel APIs; but since this is a new API, let's do it right.
This patch has been tested using an xfstest which I wrote to test it.
Link: https://lore.kernel.org/r/20191119222447.226853-1-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
Add a device-mapper target "dm-default-key" which assigns an encryption
key to bios that aren't for the contents of an encrypted file.
This ensures that all blocks on-disk will be encrypted with some key,
without the performance hit of file contents being encrypted twice when
fscrypt (File-Based Encryption) is used.
It is only appropriate to use dm-default-key when key configuration is
tightly controlled, like it is in Android, such that all fscrypt keys
are at least as hard to compromise as the default key.
Compared to the original version of dm-default-key, this has been
modified to use the new vendor-independent inline encryption framework
(which works even when no inline encryption hardware is present), the
table syntax has been changed to match dm-crypt, and support for
specifying Adiantum encryption has been added. These changes also mean
that dm-default-key now always explicitly specifies the DUN (the IV).
Also, to handle f2fs moving blocks of encrypted files around without the
key, and to handle ext4 and f2fs filesystems mounted without
'-o inlinecrypt', the mapping logic is no longer "set a key on the bio
if it doesn't have one already", but rather "set a key on the bio unless
the bio has the bi_skip_dm_default_key flag set". Filesystems set this
flag on *all* bios for encrypted file contents, regardless of whether
they are encrypting/decrypting the file using inline encryption or the
traditional filesystem-layer encryption, or moving the raw data.
For the bi_skip_dm_default_key flag, a new field in struct bio is used
rather than a bit in bi_opf so that fscrypt_set_bio_crypt_ctx() can set
the flag, minimizing the changes needed to filesystems. (bi_opf is
usually overwritten after fscrypt_set_bio_crypt_ctx() is called.)
Bug: 137270441
Bug: 147814592
Change-Id: I69c9cd1e968ccf990e4ad96e5115b662237f5095
Signed-off-by: Eric Biggers <ebiggers@google.com>
To prevent keys from being compromised if an attacker acquires read
access to kernel memory, some inline encryption hardware supports
protecting the keys in hardware without software having access to or the
ability to set the plaintext keys. Instead, software only sees "wrapped
keys", which may differ on every boot. The keys can be initially
generated either by software (in which case they need to be imported to
hardware to be wrapped), or directly by the hardware.
Add support for this type of hardware by allowing keys to be flagged as
hardware-wrapped and encryption policies to be flagged as needing a
hardware-wrapped key. When used, fscrypt will pass the wrapped key
directly to the inline encryption hardware to encrypt file contents.
The hardware is responsible for internally unwrapping the key and
deriving the actual file contents encryption key.
fscrypt also asks the inline encryption hardware to derive a
cryptographically isolated software "secret", which fscrypt then uses as
the master key for all other purposes besides file contents encryption,
e.g. to derive filenames encryption keys and the key identifier.
Bug: 147209885
Change-Id: I7f4cc5c32f130709db3eb9ebdb1ebfff5751ca95
Co-developed-by: Gaurav Kashyap <gaurkash@codeaurora.org>
Signed-off-by: Gaurav Kashyap <gaurkash@codeaurora.org>
Signed-off-by: Barani Muthukumaran <bmuthuku@codeaurora.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Currently, blk-crypto uses the algorithm to determine the size of keys.
However, some inline encryption hardware supports protecting keys from
software by wrapping the storage keys with an ephemeral key. Since
these wrapped keys are not of a fixed size, add the capability to
provide the key size when initializing a blk_crypto_key, and update the
keyslot manager to take size into account when comparing keys.
Bug: 147209885
Change-Id: I9bf26d06d18a2d671c51111b4896abe4df303988
Co-developed-by: Gaurav Kashyap <gaurkash@codeaurora.org>
Signed-off-by: Gaurav Kashyap <gaurkash@codeaurora.org>
Signed-off-by: Barani Muthukumaran <bmuthuku@codeaurora.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Merged in v5.5-rc1.
* aosp/upstream-f2fs-stable-linux-4.19.y:
docs: fs-verity: mention statx() support
f2fs: support STATX_ATTR_VERITY
ext4: support STATX_ATTR_VERITY
statx: define STATX_ATTR_VERITY
docs: fs-verity: document first supported kernel version
f2fs: add support for IV_INO_LBLK_64 encryption policies
ext4: add support for IV_INO_LBLK_64 encryption policies
fscrypt: add support for IV_INO_LBLK_64 policies
fscrypt: avoid data race on fscrypt_mode::logged_impl_name
fscrypt: zeroize fscrypt_info before freeing
fscrypt: remove struct fscrypt_ctx
fscrypt: invoke crypto API for ESSIV handling
Change-Id: I9325127228fb82b67f064ce8b3bc8d40ac76e65b
Signed-off-by: Jaegeuk Kim <jaegeuk@google.com>
Changes v5 => v6:
- Blk-crypto's kernel crypto API fallback is no longer restricted to
8-byte DUNs. It's also now separately configurable from blk-crypto, and
can be disabled entirely, while still allowing the kernel to use inline
encryption hardware. Further, struct bio_crypt_ctx takes up less space,
and no longer contains the information needed by the crypto API
fallback - the fallback allocates the required memory when necessary.
- Blk-crypto now supports all file content encryption modes supported by
fscrypt.
- Fixed bio merging logic in blk-merge.c
- Fscrypt now supports inline encryption with the direct key policy, since
blk-crypto now has support for larger DUNs.
- Keyslot manager now uses a hashtable to lookup which keyslot contains
any particular key (thanks Eric!)
- Fscrypt support for inline encryption now handles filesystems with
multiple underlying block devices (thanks Eric!)
- Numerous cleanups
Bug: 137270441
Test: refer to I26376479ee38259b8c35732cb3a1d7e15f9b05a3
Change-Id: I13e2e327e0b4784b394cb1e7cf32a04856d95f01
Link: https://lore.kernel.org/linux-block/20191218145136.172774-1-satyat@google.com/
Signed-off-by: Satya Tangirala <satyat@google.com>
Inline encryption hardware compliant with the UFS v2.1 standard or with
the upcoming version of the eMMC standard has the following properties:
(1) Per I/O request, the encryption key is specified by a previously
loaded keyslot. There might be only a small number of keyslots.
(2) Per I/O request, the starting IV is specified by a 64-bit "data unit
number" (DUN). IV bits 64-127 are assumed to be 0. The hardware
automatically increments the DUN for each "data unit" of
configurable size in the request, e.g. for each filesystem block.
Property (1) makes it inefficient to use the traditional fscrypt
per-file keys. Property (2) precludes the use of the existing
DIRECT_KEY fscrypt policy flag, which needs at least 192 IV bits.
Therefore, add a new fscrypt policy flag IV_INO_LBLK_64 which causes the
encryption to modified as follows:
- The encryption keys are derived from the master key, encryption mode
number, and filesystem UUID.
- The IVs are chosen as (inode_number << 32) | file_logical_block_num.
For filenames encryption, file_logical_block_num is 0.
Since the file nonces aren't used in the key derivation, many files may
share the same encryption key. This is much more efficient on the
target hardware. Including the inode number in the IVs and mixing the
filesystem UUID into the keys ensures that data in different files is
nevertheless still encrypted differently.
Additionally, limiting the inode and block numbers to 32 bits and
placing the block number in the low bits maintains compatibility with
the 64-bit DUN convention (property (2) above).
Since this scheme assumes that inode numbers are stable (which may
preclude filesystem shrinking) and that inode and file logical block
numbers are at most 32-bit, IV_INO_LBLK_64 will only be allowed on
filesystems that meet these constraints. These are acceptable
limitations for the cases where this format would actually be used.
Note that IV_INO_LBLK_64 is an on-disk format, not an implementation.
This patch just adds support for it using the existing filesystem layer
encryption. A later patch will add support for inline encryption.
Reviewed-by: Paul Crowley <paulcrowley@google.com>
Co-developed-by: Satya Tangirala <satyat@google.com>
Signed-off-by: Satya Tangirala <satyat@google.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
The access to logged_impl_name is technically a data race, which tools
like KCSAN could complain about in the future. See:
https://github.com/google/ktsan/wiki/READ_ONCE-and-WRITE_ONCE
Fix by using xchg(), which also ensures that only one thread does the
logging.
This also required switching from bool to int, to avoid a build error on
the RISC-V architecture which doesn't implement xchg on bytes.
Signed-off-by: Eric Biggers <ebiggers@google.com>
