* [PATCH 5.15 1/3] blk-mq: release crypto keyslot before reporting I/O complete
2023-05-04 4:03 [PATCH 5.15 0/3] blk-crypto fixes for 5.15 Eric Biggers
@ 2023-05-04 4:03 ` Eric Biggers
2023-05-04 4:03 ` [PATCH 5.15 2/3] blk-crypto: make blk_crypto_evict_key() return void Eric Biggers
2023-05-04 4:03 ` [PATCH 5.15 3/3] blk-crypto: make blk_crypto_evict_key() more robust Eric Biggers
2 siblings, 0 replies; 4+ messages in thread
From: Eric Biggers @ 2023-05-04 4:03 UTC (permalink / raw)
To: stable; +Cc: linux-block, Nathan Huckleberry, Christoph Hellwig, Jens Axboe
From: Eric Biggers <ebiggers@google.com>
commit 9cd1e566676bbcb8a126acd921e4e194e6339603 upstream.
Once all I/O using a blk_crypto_key has completed, filesystems can call
blk_crypto_evict_key(). However, the block layer currently doesn't call
blk_crypto_put_keyslot() until the request is being freed, which happens
after upper layers have been told (via bio_endio()) the I/O has
completed. This causes a race condition where blk_crypto_evict_key()
can see 'slot_refs != 0' without there being an actual bug.
This makes __blk_crypto_evict_key() hit the
'WARN_ON_ONCE(atomic_read(&slot->slot_refs) != 0)' and return without
doing anything, eventually causing a use-after-free in
blk_crypto_reprogram_all_keys(). (This is a very rare bug and has only
been seen when per-file keys are being used with fscrypt.)
There are two options to fix this: either release the keyslot before
bio_endio() is called on the request's last bio, or make
__blk_crypto_evict_key() ignore slot_refs. Let's go with the first
solution, since it preserves the ability to report bugs (via
WARN_ON_ONCE) where a key is evicted while still in-use.
Fixes: a892c8d52c02 ("block: Inline encryption support for blk-mq")
Cc: stable@vger.kernel.org
Reviewed-by: Nathan Huckleberry <nhuck@google.com>
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>
---
block/blk-core.c | 7 +++++++
block/blk-crypto-internal.h | 25 +++++++++++++++++++++----
block/blk-crypto.c | 24 ++++++++++++------------
block/blk-merge.c | 2 ++
block/blk-mq.c | 2 +-
5 files changed, 43 insertions(+), 17 deletions(-)
diff --git a/block/blk-core.c b/block/blk-core.c
index ed6271dcc1b16..0c4a4e42ad870 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1421,6 +1421,13 @@ bool blk_update_request(struct request *req, blk_status_t error,
req->q->integrity.profile->complete_fn(req, nr_bytes);
#endif
+ /*
+ * Upper layers may call blk_crypto_evict_key() anytime after the last
+ * bio_endio(). Therefore, the keyslot must be released before that.
+ */
+ if (blk_crypto_rq_has_keyslot(req) && nr_bytes >= blk_rq_bytes(req))
+ __blk_crypto_rq_put_keyslot(req);
+
if (unlikely(error && !blk_rq_is_passthrough(req) &&
!(req->rq_flags & RQF_QUIET)))
print_req_error(req, error, __func__);
diff --git a/block/blk-crypto-internal.h b/block/blk-crypto-internal.h
index 0d36aae538d7b..8e08345576203 100644
--- a/block/blk-crypto-internal.h
+++ b/block/blk-crypto-internal.h
@@ -60,6 +60,11 @@ static inline bool blk_crypto_rq_is_encrypted(struct request *rq)
return rq->crypt_ctx;
}
+static inline bool blk_crypto_rq_has_keyslot(struct request *rq)
+{
+ return rq->crypt_keyslot;
+}
+
#else /* CONFIG_BLK_INLINE_ENCRYPTION */
static inline bool bio_crypt_rq_ctx_compatible(struct request *rq,
@@ -93,6 +98,11 @@ static inline bool blk_crypto_rq_is_encrypted(struct request *rq)
return false;
}
+static inline bool blk_crypto_rq_has_keyslot(struct request *rq)
+{
+ return false;
+}
+
#endif /* CONFIG_BLK_INLINE_ENCRYPTION */
void __bio_crypt_advance(struct bio *bio, unsigned int bytes);
@@ -127,14 +137,21 @@ static inline bool blk_crypto_bio_prep(struct bio **bio_ptr)
return true;
}
-blk_status_t __blk_crypto_init_request(struct request *rq);
-static inline blk_status_t blk_crypto_init_request(struct request *rq)
+blk_status_t __blk_crypto_rq_get_keyslot(struct request *rq);
+static inline blk_status_t blk_crypto_rq_get_keyslot(struct request *rq)
{
if (blk_crypto_rq_is_encrypted(rq))
- return __blk_crypto_init_request(rq);
+ return __blk_crypto_rq_get_keyslot(rq);
return BLK_STS_OK;
}
+void __blk_crypto_rq_put_keyslot(struct request *rq);
+static inline void blk_crypto_rq_put_keyslot(struct request *rq)
+{
+ if (blk_crypto_rq_has_keyslot(rq))
+ __blk_crypto_rq_put_keyslot(rq);
+}
+
void __blk_crypto_free_request(struct request *rq);
static inline void blk_crypto_free_request(struct request *rq)
{
@@ -173,7 +190,7 @@ static inline blk_status_t blk_crypto_insert_cloned_request(struct request *rq)
{
if (blk_crypto_rq_is_encrypted(rq))
- return blk_crypto_init_request(rq);
+ return blk_crypto_rq_get_keyslot(rq);
return BLK_STS_OK;
}
diff --git a/block/blk-crypto.c b/block/blk-crypto.c
index 103c2e2d50d67..183d7439cf416 100644
--- a/block/blk-crypto.c
+++ b/block/blk-crypto.c
@@ -216,26 +216,26 @@ static bool bio_crypt_check_alignment(struct bio *bio)
return true;
}
-blk_status_t __blk_crypto_init_request(struct request *rq)
+blk_status_t __blk_crypto_rq_get_keyslot(struct request *rq)
{
return blk_ksm_get_slot_for_key(rq->q->ksm, rq->crypt_ctx->bc_key,
&rq->crypt_keyslot);
}
-/**
- * __blk_crypto_free_request - Uninitialize the crypto fields of a request.
- *
- * @rq: The request whose crypto fields to uninitialize.
- *
- * Completely uninitializes the crypto fields of a request. If a keyslot has
- * been programmed into some inline encryption hardware, that keyslot is
- * released. The rq->crypt_ctx is also freed.
- */
-void __blk_crypto_free_request(struct request *rq)
+void __blk_crypto_rq_put_keyslot(struct request *rq)
{
blk_ksm_put_slot(rq->crypt_keyslot);
+ rq->crypt_keyslot = NULL;
+}
+
+void __blk_crypto_free_request(struct request *rq)
+{
+ /* The keyslot, if one was needed, should have been released earlier. */
+ if (WARN_ON_ONCE(rq->crypt_keyslot))
+ __blk_crypto_rq_put_keyslot(rq);
+
mempool_free(rq->crypt_ctx, bio_crypt_ctx_pool);
- blk_crypto_rq_set_defaults(rq);
+ rq->crypt_ctx = NULL;
}
/**
diff --git a/block/blk-merge.c b/block/blk-merge.c
index d1435b6572977..1affc5fd35f0c 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -818,6 +818,8 @@ static struct request *attempt_merge(struct request_queue *q,
if (!blk_discard_mergable(req))
elv_merge_requests(q, req, next);
+ blk_crypto_rq_put_keyslot(next);
+
/*
* 'next' is going away, so update stats accordingly
*/
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 01e281801453d..bbbbcd2c19418 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -2228,7 +2228,7 @@ blk_qc_t blk_mq_submit_bio(struct bio *bio)
blk_mq_bio_to_request(rq, bio, nr_segs);
- ret = blk_crypto_init_request(rq);
+ ret = blk_crypto_rq_get_keyslot(rq);
if (ret != BLK_STS_OK) {
bio->bi_status = ret;
bio_endio(bio);
--
2.40.1
^ permalink raw reply related [flat|nested] 4+ messages in thread* [PATCH 5.15 2/3] blk-crypto: make blk_crypto_evict_key() return void
2023-05-04 4:03 [PATCH 5.15 0/3] blk-crypto fixes for 5.15 Eric Biggers
2023-05-04 4:03 ` [PATCH 5.15 1/3] blk-mq: release crypto keyslot before reporting I/O complete Eric Biggers
@ 2023-05-04 4:03 ` Eric Biggers
2023-05-04 4:03 ` [PATCH 5.15 3/3] blk-crypto: make blk_crypto_evict_key() more robust Eric Biggers
2 siblings, 0 replies; 4+ messages in thread
From: Eric Biggers @ 2023-05-04 4:03 UTC (permalink / raw)
To: stable; +Cc: linux-block, Christoph Hellwig, Jens Axboe
From: Eric Biggers <ebiggers@google.com>
commit 70493a63ba04f754f7a7dd53a4fcc82700181490 upstream.
blk_crypto_evict_key() is only called in contexts such as inode eviction
where failure is not an option. So there is nothing the caller can do
with errors except log them. (dm-table.c does "use" the error code, but
only to pass on to upper layers, so it doesn't really count.)
Just make blk_crypto_evict_key() return void and log errors itself.
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>
---
block/blk-crypto.c | 22 ++++++++++------------
drivers/md/dm-table.c | 19 +++++--------------
include/linux/blk-crypto.h | 4 ++--
3 files changed, 17 insertions(+), 28 deletions(-)
diff --git a/block/blk-crypto.c b/block/blk-crypto.c
index 183d7439cf416..686c657f91917 100644
--- a/block/blk-crypto.c
+++ b/block/blk-crypto.c
@@ -13,6 +13,7 @@
#include <linux/blkdev.h>
#include <linux/keyslot-manager.h>
#include <linux/module.h>
+#include <linux/ratelimit.h>
#include <linux/slab.h>
#include "blk-crypto-internal.h"
@@ -393,20 +394,17 @@ int blk_crypto_start_using_key(const struct blk_crypto_key *key,
* Upper layers (filesystems) must call this function to ensure that a key is
* evicted from any hardware that it might have been programmed into. The key
* must not be in use by any in-flight IO when this function is called.
- *
- * Return: 0 on success or if key is not present in the q's ksm, -err on error.
*/
-int blk_crypto_evict_key(struct request_queue *q,
- const struct blk_crypto_key *key)
+void blk_crypto_evict_key(struct request_queue *q,
+ const struct blk_crypto_key *key)
{
- if (blk_ksm_crypto_cfg_supported(q->ksm, &key->crypto_cfg))
- return blk_ksm_evict_key(q->ksm, key);
+ int err;
- /*
- * If the request queue's associated inline encryption hardware didn't
- * have support for the key, then the key might have been programmed
- * into the fallback keyslot manager, so try to evict from there.
- */
- return blk_crypto_fallback_evict_key(key);
+ if (blk_ksm_crypto_cfg_supported(q->ksm, &key->crypto_cfg))
+ err = blk_ksm_evict_key(q->ksm, key);
+ else
+ err = blk_crypto_fallback_evict_key(key);
+ if (err)
+ pr_warn_ratelimited("error %d evicting key\n", err);
}
EXPORT_SYMBOL_GPL(blk_crypto_evict_key);
diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index 2111daaacabaf..46ec4590f62f6 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -1191,21 +1191,12 @@ struct dm_keyslot_manager {
struct mapped_device *md;
};
-struct dm_keyslot_evict_args {
- const struct blk_crypto_key *key;
- int err;
-};
-
static int dm_keyslot_evict_callback(struct dm_target *ti, struct dm_dev *dev,
sector_t start, sector_t len, void *data)
{
- struct dm_keyslot_evict_args *args = data;
- int err;
+ const struct blk_crypto_key *key = data;
- err = blk_crypto_evict_key(bdev_get_queue(dev->bdev), args->key);
- if (!args->err)
- args->err = err;
- /* Always try to evict the key from all devices. */
+ blk_crypto_evict_key(bdev_get_queue(dev->bdev), key);
return 0;
}
@@ -1220,7 +1211,6 @@ static int dm_keyslot_evict(struct blk_keyslot_manager *ksm,
struct dm_keyslot_manager,
ksm);
struct mapped_device *md = dksm->md;
- struct dm_keyslot_evict_args args = { key };
struct dm_table *t;
int srcu_idx;
int i;
@@ -1233,10 +1223,11 @@ static int dm_keyslot_evict(struct blk_keyslot_manager *ksm,
ti = dm_table_get_target(t, i);
if (!ti->type->iterate_devices)
continue;
- ti->type->iterate_devices(ti, dm_keyslot_evict_callback, &args);
+ ti->type->iterate_devices(ti, dm_keyslot_evict_callback,
+ (void *)key);
}
dm_put_live_table(md, srcu_idx);
- return args.err;
+ return 0;
}
static const struct blk_ksm_ll_ops dm_ksm_ll_ops = {
diff --git a/include/linux/blk-crypto.h b/include/linux/blk-crypto.h
index 69b24fe92cbf1..5e96bad548047 100644
--- a/include/linux/blk-crypto.h
+++ b/include/linux/blk-crypto.h
@@ -97,8 +97,8 @@ int blk_crypto_init_key(struct blk_crypto_key *blk_key, const u8 *raw_key,
int blk_crypto_start_using_key(const struct blk_crypto_key *key,
struct request_queue *q);
-int blk_crypto_evict_key(struct request_queue *q,
- const struct blk_crypto_key *key);
+void blk_crypto_evict_key(struct request_queue *q,
+ const struct blk_crypto_key *key);
bool blk_crypto_config_supported(struct request_queue *q,
const struct blk_crypto_config *cfg);
--
2.40.1
^ permalink raw reply related [flat|nested] 4+ messages in thread* [PATCH 5.15 3/3] blk-crypto: make blk_crypto_evict_key() more robust
2023-05-04 4:03 [PATCH 5.15 0/3] blk-crypto fixes for 5.15 Eric Biggers
2023-05-04 4:03 ` [PATCH 5.15 1/3] blk-mq: release crypto keyslot before reporting I/O complete Eric Biggers
2023-05-04 4:03 ` [PATCH 5.15 2/3] blk-crypto: make blk_crypto_evict_key() return void Eric Biggers
@ 2023-05-04 4:03 ` Eric Biggers
2 siblings, 0 replies; 4+ messages in thread
From: Eric Biggers @ 2023-05-04 4:03 UTC (permalink / raw)
To: stable; +Cc: linux-block, Christoph Hellwig, Jens Axboe
From: Eric Biggers <ebiggers@google.com>
commit 5c7cb94452901a93e90c2230632e2c12a681bc92 upstream.
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>
---
block/blk-crypto.c | 29 +++++++++++++++++++--------
block/keyslot-manager.c | 43 ++++++++++++++++++++---------------------
2 files changed, 42 insertions(+), 30 deletions(-)
diff --git a/block/blk-crypto.c b/block/blk-crypto.c
index 686c657f91917..5029a50807d5d 100644
--- a/block/blk-crypto.c
+++ b/block/blk-crypto.c
@@ -385,15 +385,20 @@ int blk_crypto_start_using_key(const struct blk_crypto_key *key,
}
/**
- * blk_crypto_evict_key() - Evict a key from any inline encryption hardware
- * it may have been programmed into
- * @q: The request queue who's associated inline encryption hardware this key
- * might have been programmed into
- * @key: The key to evict
+ * blk_crypto_evict_key() - Evict a blk_crypto_key from a request_queue
+ * @q: a request_queue on which I/O using the key may have been done
+ * @key: the key to evict
*
- * Upper layers (filesystems) must call this function to ensure that a key is
- * evicted from any hardware that it might have been programmed into. The key
- * must not be in use by any in-flight IO when this function is called.
+ * For a given request_queue, this function removes the given blk_crypto_key
+ * from the keyslot management structures and evicts it from any underlying
+ * hardware keyslot(s) or blk-crypto-fallback keyslot it may have been
+ * programmed into.
+ *
+ * Upper layers must call this before freeing the blk_crypto_key. It must be
+ * called for every request_queue the key may have been used on. The key must
+ * no longer be in use by any I/O when this function is called.
+ *
+ * Context: May sleep.
*/
void blk_crypto_evict_key(struct request_queue *q,
const struct blk_crypto_key *key)
@@ -404,6 +409,14 @@ void blk_crypto_evict_key(struct request_queue *q,
err = blk_ksm_evict_key(q->ksm, key);
else
err = blk_crypto_fallback_evict_key(key);
+ /*
+ * An error can only occur here if the key failed to be evicted from a
+ * keyslot (due to a hardware or driver issue) or is allegedly still in
+ * use by I/O (due to a kernel bug). Even in these cases, the key is
+ * still unlinked from the keyslot management structures, and the caller
+ * is allowed and expected to free it right away. There's nothing
+ * callers can do to handle errors, so just log them and return void.
+ */
if (err)
pr_warn_ratelimited("error %d evicting key\n", err);
}
diff --git a/block/keyslot-manager.c b/block/keyslot-manager.c
index 2c4a55bea6ca1..2a7a36551cfae 100644
--- a/block/keyslot-manager.c
+++ b/block/keyslot-manager.c
@@ -343,25 +343,16 @@ bool blk_ksm_crypto_cfg_supported(struct blk_keyslot_manager *ksm,
return true;
}
-/**
- * blk_ksm_evict_key() - Evict a key from the lower layer device.
- * @ksm: The keyslot manager to evict from
- * @key: The key to evict
- *
- * Find the keyslot that the specified key was programmed into, and evict that
- * slot from the lower layer device. The slot must not be in use by any
- * in-flight IO when this function is called.
- *
- * Context: Process context. Takes and releases ksm->lock.
- * Return: 0 on success or if there's no keyslot with the specified key, -EBUSY
- * if the keyslot is still in use, or another -errno value on other
- * error.
+/*
+ * This is an internal function that evicts a key from an inline encryption
+ * device that can be either a real device or the blk-crypto-fallback "device".
+ * It is used only by blk_crypto_evict_key(); see that function for details.
*/
int blk_ksm_evict_key(struct blk_keyslot_manager *ksm,
const struct blk_crypto_key *key)
{
struct blk_ksm_keyslot *slot;
- int err = 0;
+ int err;
if (blk_ksm_is_passthrough(ksm)) {
if (ksm->ksm_ll_ops.keyslot_evict) {
@@ -375,22 +366,30 @@ int blk_ksm_evict_key(struct blk_keyslot_manager *ksm,
blk_ksm_hw_enter(ksm);
slot = blk_ksm_find_keyslot(ksm, key);
- if (!slot)
- goto out_unlock;
+ if (!slot) {
+ /*
+ * Not an error, since a key not in use by I/O is not guaranteed
+ * to be in a keyslot. There can be more keys than keyslots.
+ */
+ err = 0;
+ goto out;
+ }
if (WARN_ON_ONCE(atomic_read(&slot->slot_refs) != 0)) {
+ /* BUG: key is still in use by I/O */
err = -EBUSY;
- goto out_unlock;
+ goto out_remove;
}
err = ksm->ksm_ll_ops.keyslot_evict(ksm, key,
blk_ksm_get_slot_idx(slot));
- if (err)
- goto out_unlock;
-
+out_remove:
+ /*
+ * Callers free the key even on error, so unlink the key from the hash
+ * table and clear slot->key even on error.
+ */
hlist_del(&slot->hash_node);
slot->key = NULL;
- err = 0;
-out_unlock:
+out:
blk_ksm_hw_exit(ksm);
return err;
}
--
2.40.1
^ permalink raw reply related [flat|nested] 4+ messages in thread