crypto: ctr - convert to skcipher API

Convert the CTR template from the deprecated "blkcipher" API to the
"skcipher" API, taking advantage of skcipher_alloc_instance_simple() to
simplify it considerably.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 41 insertions, 119 deletions

diff --git a/crypto/ctr.c b/crypto/ctr.c
index 30f3946efc6d..4c743a96faa4 100644
--- a/crypto/ctr.c
+++ b/crypto/ctr.c
@@ -17,14 +17,8 @@
 #include <linux/init.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
-#include <linux/random.h>
-#include <linux/scatterlist.h>
 #include <linux/slab.h>
 
-struct crypto_ctr_ctx {
-        struct crypto_cipher *child;
-};
-
 struct crypto_rfc3686_ctx {
         struct crypto_skcipher *child;
         u8 nonce[CTR_RFC3686_NONCE_SIZE];
@@ -35,24 +29,7 @@ struct crypto_rfc3686_req_ctx {
         struct skcipher_request subreq CRYPTO_MINALIGN_ATTR;
 };
 
-static int crypto_ctr_setkey(struct crypto_tfm *parent, const u8 *key,
-                             unsigned int keylen)
-{
-        struct crypto_ctr_ctx *ctx = crypto_tfm_ctx(parent);
-        struct crypto_cipher *child = ctx->child;
-        int err;
-
-        crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
-        crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) &
-                                CRYPTO_TFM_REQ_MASK);
-        err = crypto_cipher_setkey(child, key, keylen);
-        crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) &
-                             CRYPTO_TFM_RES_MASK);
-
-        return err;
-}
-
-static void crypto_ctr_crypt_final(struct blkcipher_walk *walk,
+static void crypto_ctr_crypt_final(struct skcipher_walk *walk,
                                    struct crypto_cipher *tfm)
 {
         unsigned int bsize = crypto_cipher_blocksize(tfm);
@@ -70,7 +47,7 @@ static void crypto_ctr_crypt_final(struct blkcipher_walk *walk,
         crypto_inc(ctrblk, bsize);
 }
 
-static int crypto_ctr_crypt_segment(struct blkcipher_walk *walk,
+static int crypto_ctr_crypt_segment(struct skcipher_walk *walk,
                                     struct crypto_cipher *tfm)
 {
         void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
@@ -96,7 +73,7 @@ static int crypto_ctr_crypt_segment(struct blkcipher_walk *walk,
         return nbytes;
 }
 
-static int crypto_ctr_crypt_inplace(struct blkcipher_walk *walk,
+static int crypto_ctr_crypt_inplace(struct skcipher_walk *walk,
                                     struct crypto_cipher *tfm)
 {
         void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
@@ -123,135 +100,80 @@ static int crypto_ctr_crypt_inplace(struct blkcipher_walk *walk,
         return nbytes;
 }
 
-static int crypto_ctr_crypt(struct blkcipher_desc *desc,
-                              struct scatterlist *dst, struct scatterlist *src,
-                              unsigned int nbytes)
+static int crypto_ctr_crypt(struct skcipher_request *req)
 {
-        struct blkcipher_walk walk;
-        struct crypto_blkcipher *tfm = desc->tfm;
-        struct crypto_ctr_ctx *ctx = crypto_blkcipher_ctx(tfm);
-        struct crypto_cipher *child = ctx->child;
-        unsigned int bsize = crypto_cipher_blocksize(child);
+        struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
+        struct crypto_cipher *cipher = skcipher_cipher_simple(tfm);
+        const unsigned int bsize = crypto_cipher_blocksize(cipher);
+        struct skcipher_walk walk;
+        unsigned int nbytes;
         int err;
 
-        blkcipher_walk_init(&walk, dst, src, nbytes);
-        err = blkcipher_walk_virt_block(desc, &walk, bsize);
+        err = skcipher_walk_virt(&walk, req, false);
 
         while (walk.nbytes >= bsize) {
                 if (walk.src.virt.addr == walk.dst.virt.addr)
-                        nbytes = crypto_ctr_crypt_inplace(&walk, child);
+                        nbytes = crypto_ctr_crypt_inplace(&walk, cipher);
                 else
-                        nbytes = crypto_ctr_crypt_segment(&walk, child);
+                        nbytes = crypto_ctr_crypt_segment(&walk, cipher);
 
-                err = blkcipher_walk_done(desc, &walk, nbytes);
+                err = skcipher_walk_done(&walk, nbytes);
         }
 
         if (walk.nbytes) {
-                crypto_ctr_crypt_final(&walk, child);
-                err = blkcipher_walk_done(desc, &walk, 0);
+                crypto_ctr_crypt_final(&walk, cipher);
+                err = skcipher_walk_done(&walk, 0);
         }
 
         return err;
 }
 
-static int crypto_ctr_init_tfm(struct crypto_tfm *tfm)
+static int crypto_ctr_create(struct crypto_template *tmpl, struct rtattr **tb)
 {
-        struct crypto_instance *inst = (void *)tfm->__crt_alg;
-        struct crypto_spawn *spawn = crypto_instance_ctx(inst);
-        struct crypto_ctr_ctx *ctx = crypto_tfm_ctx(tfm);
-        struct crypto_cipher *cipher;
-
-        cipher = crypto_spawn_cipher(spawn);
-        if (IS_ERR(cipher))
-                return PTR_ERR(cipher);
-
-        ctx->child = cipher;
-
-        return 0;
-}
-
-static void crypto_ctr_exit_tfm(struct crypto_tfm *tfm)
-{
-        struct crypto_ctr_ctx *ctx = crypto_tfm_ctx(tfm);
-
-        crypto_free_cipher(ctx->child);
-}
-
-static struct crypto_instance *crypto_ctr_alloc(struct rtattr **tb)
-{
-        struct crypto_instance *inst;
-        struct crypto_attr_type *algt;
+        struct skcipher_instance *inst;
         struct crypto_alg *alg;
-        u32 mask;
         int err;
 
-        err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_BLKCIPHER);
-        if (err)
-                return ERR_PTR(err);
-
-        algt = crypto_get_attr_type(tb);
-        if (IS_ERR(algt))
-                return ERR_CAST(algt);
-
-        mask = CRYPTO_ALG_TYPE_MASK |
-                crypto_requires_off(algt->type, algt->mask,
-                                    CRYPTO_ALG_NEED_FALLBACK);
-
-        alg = crypto_attr_alg(tb[1], CRYPTO_ALG_TYPE_CIPHER, mask);
-        if (IS_ERR(alg))
-                return ERR_CAST(alg);
+        inst = skcipher_alloc_instance_simple(tmpl, tb, &alg);
+        if (IS_ERR(inst))
+                return PTR_ERR(inst);
 
         /* Block size must be >= 4 bytes. */
         err = -EINVAL;
         if (alg->cra_blocksize < 4)
-                goto out_put_alg;
+                goto out_free_inst;
 
         /* If this is false we'd fail the alignment of crypto_inc. */
         if (alg->cra_blocksize % 4)
-                goto out_put_alg;
-
-        inst = crypto_alloc_instance("ctr", alg);
-        if (IS_ERR(inst))
-                goto out;
-
-        inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER;
-        inst->alg.cra_priority = alg->cra_priority;
-        inst->alg.cra_blocksize = 1;
-        inst->alg.cra_alignmask = alg->cra_alignmask;
-        inst->alg.cra_type = &crypto_blkcipher_type;
+                goto out_free_inst;
 
-        inst->alg.cra_blkcipher.ivsize = alg->cra_blocksize;
-        inst->alg.cra_blkcipher.min_keysize = alg->cra_cipher.cia_min_keysize;
-        inst->alg.cra_blkcipher.max_keysize = alg->cra_cipher.cia_max_keysize;
-
-        inst->alg.cra_ctxsize = sizeof(struct crypto_ctr_ctx);
+        /* CTR mode is a stream cipher. */
+        inst->alg.base.cra_blocksize = 1;
 
-        inst->alg.cra_init = crypto_ctr_init_tfm;
-        inst->alg.cra_exit = crypto_ctr_exit_tfm;
+        /*
+         * To simplify the implementation, configure the skcipher walk to only
+         * give a partial block at the very end, never earlier.
+         */
+        inst->alg.chunksize = alg->cra_blocksize;
 
-        inst->alg.cra_blkcipher.setkey = crypto_ctr_setkey;
-        inst->alg.cra_blkcipher.encrypt = crypto_ctr_crypt;
-        inst->alg.cra_blkcipher.decrypt = crypto_ctr_crypt;
+        inst->alg.encrypt = crypto_ctr_crypt;
+        inst->alg.decrypt = crypto_ctr_crypt;
 
-out:
-        crypto_mod_put(alg);
-        return inst;
+        err = skcipher_register_instance(tmpl, inst);
+        if (err)
+                goto out_free_inst;
+        goto out_put_alg;
 
+out_free_inst:
+        inst->free(inst);
 out_put_alg:
-        inst = ERR_PTR(err);
-        goto out;
-}
-
-static void crypto_ctr_free(struct crypto_instance *inst)
-{
-        crypto_drop_spawn(crypto_instance_ctx(inst));
-        kfree(inst);
+        crypto_mod_put(alg);
+        return err;
 }
 
 static struct crypto_template crypto_ctr_tmpl = {
         .name = "ctr",
-        .alloc = crypto_ctr_alloc,
-        .free = crypto_ctr_free,
+        .create = crypto_ctr_create,
         .module = THIS_MODULE,
 };
 
@@ -480,6 +402,6 @@ module_init(crypto_ctr_module_init);
 module_exit(crypto_ctr_module_exit);
 
 MODULE_LICENSE("GPL");
-MODULE_DESCRIPTION("CTR Counter block mode");
+MODULE_DESCRIPTION("CTR block cipher mode of operation");
 MODULE_ALIAS_CRYPTO("rfc3686");
 MODULE_ALIAS_CRYPTO("ctr");