diff mbox series

dm crypt: Avoid using MAX_CIPHER_BLOCKSIZE

Message ID ZHhbL+SbWRnTW4b7@gondor.apana.org.au
State Accepted
Commit e3023094dffb41540330fb0c74cd3a019cd525c2
Headers show
Series dm crypt: Avoid using MAX_CIPHER_BLOCKSIZE | expand

Commit Message

Herbert Xu June 1, 2023, 8:47 a.m. UTC 
MAX_CIPHER_BLOCKSIZE is an internal implementation detail and should
not be relied on by users of the Crypto API.

Instead of storing the IV on the stack, allocate it together with
the crypto request.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
---

 drivers/md/dm-crypt.c |   15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

Comments

Herbert Xu June 9, 2023, 9:25 a.m. UTC | #1 
On Thu, Jun 01, 2023 at 03:10:18PM -0400, Mike Snitzer wrote:
>
> Strikes me as strange that open-coding skcipher_request_{alloc,free}
> is ideal, but dm-crypt is the only non-crypto consumer of
> MAX_CIPHER_BLOCKSIZE so really not worth standing up yet another
> interface wrapper.

It is pretty standard when you need to allocate data alongside the
request.  But yes if we could improve the helpers to handle this
that would be nice.

> Anyway, this code is certainly better for dm-crypt's needs.  I'm happy
> with you applying this change via your crypto tree.
> 
> Reviewed-by: Mike Snitzer <snitzer@kernel.org>

Thanks!
diff mbox series

Patch

diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index 40cb1719ae4d..0e7e443dde11 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -31,10 +31,10 @@ 
 #include <asm/unaligned.h>
 #include <crypto/hash.h>
 #include <crypto/md5.h>
-#include <crypto/algapi.h>
 #include <crypto/skcipher.h>
 #include <crypto/aead.h>
 #include <crypto/authenc.h>
+#include <crypto/utils.h>
 #include <linux/rtnetlink.h> /* for struct rtattr and RTA macros only */
 #include <linux/key-type.h>
 #include <keys/user-type.h>
@@ -743,16 +743,23 @@  static int crypt_iv_eboiv_ctr(struct crypt_config *cc, struct dm_target *ti,
 static int crypt_iv_eboiv_gen(struct crypt_config *cc, u8 *iv,
 			    struct dm_crypt_request *dmreq)
 {
-	u8 buf[MAX_CIPHER_BLOCKSIZE] __aligned(__alignof__(__le64));
+	struct crypto_skcipher *tfm = any_tfm(cc);
 	struct skcipher_request *req;
 	struct scatterlist src, dst;
 	DECLARE_CRYPTO_WAIT(wait);
+	unsigned int reqsize;
 	int err;
+	u8 *buf;
 
-	req = skcipher_request_alloc(any_tfm(cc), GFP_NOIO);
+	reqsize = ALIGN(crypto_skcipher_reqsize(tfm), __alignof__(__le64));
+
+	req = kmalloc(reqsize + cc->iv_size, GFP_NOIO);
 	if (!req)
 		return -ENOMEM;
 
+	skcipher_request_set_tfm(req, tfm);
+
+	buf = (u8 *)req + reqsize;
 	memset(buf, 0, cc->iv_size);
 	*(__le64 *)buf = cpu_to_le64(dmreq->iv_sector * cc->sector_size);
 
@@ -761,7 +768,7 @@  static int crypt_iv_eboiv_gen(struct crypt_config *cc, u8 *iv,
 	skcipher_request_set_crypt(req, &src, &dst, cc->iv_size, buf);
 	skcipher_request_set_callback(req, 0, crypto_req_done, &wait);
 	err = crypto_wait_req(crypto_skcipher_encrypt(req), &wait);
-	skcipher_request_free(req);
+	kfree_sensitive(req);
 
 	return err;
 }