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When a device-mapper device is passing through the inline encryption
support of an underlying device, calls to blk_crypto_evict_key() take
the blk_crypto_profile::lock of the device-mapper device, then take the
blk_crypto_profile::lock of the underlying device (nested). This isn't
a real deadlock, but it causes a lockdep report because there is only
one lock class for all instances of this lock.
Lockdep subclasses don't really work here because the hierarchy of block
devices is dynamic and could have more than 2 levels.
Instead, register a dynamic lock class for each blk_crypto_profile, and
associate that with the lock.
This avoids false-positive lockdep reports like the following:
============================================
WARNING: possible recursive locking detected
6.4.0-rc5 #2 Not tainted
--------------------------------------------
fscryptctl/1421 is trying to acquire lock:
ffffff80829ca418 (&profile->lock){++++}-{3:3}, at: __blk_crypto_evict_key+0x44/0x1c0
but task is already holding lock:
ffffff8086b68ca8 (&profile->lock){++++}-{3:3}, at: __blk_crypto_evict_key+0xc8/0x1c0
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(&profile->lock);
lock(&profile->lock);
*** DEADLOCK ***
May be due to missing lock nesting notation
Fixes: 1b2628397058 ("block: Keyslot Manager for Inline Encryption")
Reported-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20230610061139.212085-1-ebiggers@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Now that all callers of blk_crypto_put_keyslot() check for NULL before
calling it, there is no need for blk_crypto_put_keyslot() to do the NULL
check itself.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Link: https://lore.kernel.org/r/20230315183907.53675-2-ebiggers@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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If blk_crypto_evict_key() sees that the key is still in-use (due to a
bug) or that ->keyslot_evict failed, it currently just returns while
leaving the key linked into the keyslot management structures.
However, blk_crypto_evict_key() is only called in contexts such as inode
eviction where failure is not an option. So actually the caller
proceeds with freeing the blk_crypto_key regardless of the return value
of blk_crypto_evict_key().
These two assumptions don't match, and the result is that there can be a
use-after-free in blk_crypto_reprogram_all_keys() after one of these
errors occurs. (Note, these errors *shouldn't* happen; we're just
talking about what happens if they do anyway.)
Fix this by making blk_crypto_evict_key() unlink the key from the
keyslot management structures even on failure.
Also improve some comments.
Fixes: 1b2628397058 ("block: Keyslot Manager for Inline Encryption")
Cc: stable@vger.kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20230315183907.53675-2-ebiggers@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Allow the compiler to verify consistency of function declarations and
function definitions. This patch fixes the following sparse errors:
block/blk-crypto-profile.c:241:14: error: no previous prototype for ‘blk_crypto_get_keyslot’ [-Werror=missing-prototypes]
241 | blk_status_t blk_crypto_get_keyslot(struct blk_crypto_profile *profile,
| ^~~~~~~~~~~~~~~~~~~~~~
block/blk-crypto-profile.c:318:6: error: no previous prototype for ‘blk_crypto_put_keyslot’ [-Werror=missing-prototypes]
318 | void blk_crypto_put_keyslot(struct blk_crypto_keyslot *slot)
| ^~~~~~~~~~~~~~~~~~~~~~
block/blk-crypto-profile.c:344:6: error: no previous prototype for ‘__blk_crypto_cfg_supported’ [-Werror=missing-prototypes]
344 | bool __blk_crypto_cfg_supported(struct blk_crypto_profile *profile,
| ^~~~~~~~~~~~~~~~~~~~~~~~~~
block/blk-crypto-profile.c:373:5: error: no previous prototype for ‘__blk_crypto_evict_key’ [-Werror=missing-prototypes]
373 | int __blk_crypto_evict_key(struct blk_crypto_profile *profile,
| ^~~~~~~~~~~~~~~~~~~~~~
Cc: Eric Biggers <ebiggers@google.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20221123172923.434339-1-bvanassche@acm.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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This function is trivial and is only used in one place. Having this
function is misleading because it implies that blk_crypto_register()
needs to be paired with blk_crypto_unregister(), which is not the case.
Just set disk->queue->crypto_profile to NULL directly.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211124013733.347612-1-ebiggers@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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blk_keyslot_manager is misnamed because it doesn't necessarily manage
keyslots. It actually does several different things:
- Contains the crypto capabilities of the device.
- Provides functions to control the inline encryption hardware.
Originally these were just for programming/evicting keyslots;
however, new functionality (hardware-wrapped keys) will require new
functions here which are unrelated to keyslots. Moreover,
device-mapper devices already (ab)use "keyslot_evict" to pass key
eviction requests to their underlying devices even though
device-mapper devices don't have any keyslots themselves (so it
really should be "evict_key", not "keyslot_evict").
- Sometimes (but not always!) it manages keyslots. Originally it
always did, but device-mapper devices don't have keyslots
themselves, so they use a "passthrough keyslot manager" which
doesn't actually manage keyslots. This hack works, but the
terminology is unnatural. Also, some hardware doesn't have keyslots
and thus also uses a "passthrough keyslot manager" (support for such
hardware is yet to be upstreamed, but it will happen eventually).
Let's stop having keyslot managers which don't actually manage keyslots.
Instead, rename blk_keyslot_manager to blk_crypto_profile.
This is a fairly big change, since for consistency it also has to update
keyslot manager-related function names, variable names, and comments --
not just the actual struct name. However it's still a fairly
straightforward change, as it doesn't change any actual functionality.
Acked-by: Ulf Hansson <ulf.hansson@linaro.org> # For MMC
Reviewed-by: Mike Snitzer <snitzer@redhat.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Link: https://lore.kernel.org/r/20211018180453.40441-4-ebiggers@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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In preparation for renaming struct blk_keyslot_manager to struct
blk_crypto_profile, rename the keyslot-manager.h and keyslot-manager.c
source files. Renaming these files separately before making a lot of
changes to their contents makes it easier for git to understand that
they were renamed.
Acked-by: Ulf Hansson <ulf.hansson@linaro.org> # For MMC
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Mike Snitzer <snitzer@redhat.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Link: https://lore.kernel.org/r/20211018180453.40441-3-ebiggers@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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