block: cryptoloop: Remove VLA usage of skcipher

In the quest to remove all stack VLA usage from the kernel[1], this
replaces struct crypto_skcipher and SKCIPHER_REQUEST_ON_STACK() usage
with struct crypto_sync_skcipher and SYNC_SKCIPHER_REQUEST_ON_STACK(),
which uses a fixed stack size.

[1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com

Cc: Jens Axboe <axboe@kernel.dk>
Cc: linux-block@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/drivers/block/cryptoloop.c b/drivers/block/cryptoloop.c
index 7033a4b..254ee7d 100644 (file)
--- a/drivers/block/cryptoloop.c
+++ b/drivers/block/cryptoloop.c
@@ -45,7 +45,7 @@ cryptoloop_init(struct loop_device *lo, const struct loop_info64 *info)
        char cms[LO_NAME_SIZE];                 /* cipher-mode string */
        char *mode;
        char *cmsp = cms;                       /* c-m string pointer */
-       struct crypto_skcipher *tfm;
+       struct crypto_sync_skcipher *tfm;
 
        /* encryption breaks for non sector aligned offsets */
 
@@ -80,13 +80,13 @@ cryptoloop_init(struct loop_device *lo, const struct loop_info64 *info)
        *cmsp++ = ')';
        *cmsp = 0;
 
-       tfm = crypto_alloc_skcipher(cms, 0, CRYPTO_ALG_ASYNC);
+       tfm = crypto_alloc_sync_skcipher(cms, 0, 0);
        if (IS_ERR(tfm))
                return PTR_ERR(tfm);
 
-       err = crypto_skcipher_setkey(tfm, info->lo_encrypt_key,
-                                    info->lo_encrypt_key_size);
-       
+       err = crypto_sync_skcipher_setkey(tfm, info->lo_encrypt_key,
+                                         info->lo_encrypt_key_size);
+
        if (err != 0)
                goto out_free_tfm;
 
@@ -94,7 +94,7 @@ cryptoloop_init(struct loop_device *lo, const struct loop_info64 *info)
        return 0;
 
  out_free_tfm:
-       crypto_free_skcipher(tfm);
+       crypto_free_sync_skcipher(tfm);
 
  out:
        return err;
@@ -109,8 +109,8 @@ cryptoloop_transfer(struct loop_device *lo, int cmd,
                    struct page *loop_page, unsigned loop_off,
                    int size, sector_t IV)
 {
-       struct crypto_skcipher *tfm = lo->key_data;
-       SKCIPHER_REQUEST_ON_STACK(req, tfm);
+       struct crypto_sync_skcipher *tfm = lo->key_data;
+       SYNC_SKCIPHER_REQUEST_ON_STACK(req, tfm);
        struct scatterlist sg_out;
        struct scatterlist sg_in;
 
@@ -119,7 +119,7 @@ cryptoloop_transfer(struct loop_device *lo, int cmd,
        unsigned in_offs, out_offs;
        int err;
 
-       skcipher_request_set_tfm(req, tfm);
+       skcipher_request_set_sync_tfm(req, tfm);
        skcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP,
                                      NULL, NULL);
 
@@ -175,9 +175,9 @@ cryptoloop_ioctl(struct loop_device *lo, int cmd, unsigned long arg)
 static int
 cryptoloop_release(struct loop_device *lo)
 {
-       struct crypto_skcipher *tfm = lo->key_data;
+       struct crypto_sync_skcipher *tfm = lo->key_data;
        if (tfm != NULL) {
-               crypto_free_skcipher(tfm);
+               crypto_free_sync_skcipher(tfm);
                lo->key_data = NULL;
                return 0;
        }