[CRYPTO] ctr: Refactor into ctr and rfc3686

As discussed previously, this patch moves the basic CTR functionality
into a chainable algorithm called ctr.  The IPsec-specific variant of
it is now placed on top with the name rfc3686.

So ctr(aes) gives a chainable cipher with IV size 16 while the IPsec
variant will be called rfc3686(ctr(aes)).  This patch also adjusts
gcm accordingly.

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

1 files changed, 206 insertions, 128 deletions

diff --git a/crypto/ctr.c b/crypto/ctr.c
index 57da7d0affcb..1052b318aed2 100644
--- a/crypto/ctr.c
+++ b/crypto/ctr.c
@@ -11,6 +11,7 @@
  */
 
 #include <crypto/algapi.h>
+#include <crypto/ctr.h>
 #include <linux/err.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
@@ -19,16 +20,13 @@
 #include <linux/scatterlist.h>
 #include <linux/slab.h>
 
-struct ctr_instance_ctx {
-        struct crypto_spawn alg;
-        unsigned int noncesize;
-        unsigned int ivsize;
-        unsigned int countersize;
-};
-
 struct crypto_ctr_ctx {
         struct crypto_cipher *child;
-        u8 *nonce;
+};
+
+struct crypto_rfc3686_ctx {
+        struct crypto_blkcipher *child;
+        u8 nonce[CTR_RFC3686_NONCE_SIZE];
 };
 
 static int crypto_ctr_setkey(struct crypto_tfm *parent, const u8 *key,
@@ -36,18 +34,7 @@ static int crypto_ctr_setkey(struct crypto_tfm *parent, const u8 *key,
 {
         struct crypto_ctr_ctx *ctx = crypto_tfm_ctx(parent);
         struct crypto_cipher *child = ctx->child;
-        struct ctr_instance_ctx *ictx =
-                crypto_instance_ctx(crypto_tfm_alg_instance(parent));
-        unsigned int noncelen = ictx->noncesize;
-        int err = 0;
-
-        /* the nonce is stored in bytes at end of key */
-        if (keylen < noncelen)
-                return  -EINVAL;
-
-        memcpy(ctx->nonce, key + (keylen - noncelen), noncelen);
-
-        keylen -=  noncelen;
+        int err;
 
         crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
         crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) &
@@ -60,11 +47,13 @@ static int crypto_ctr_setkey(struct crypto_tfm *parent, const u8 *key,
 }
 
 static void crypto_ctr_crypt_final(struct blkcipher_walk *walk,
-                                   struct crypto_cipher *tfm, u8 *ctrblk,
-                                   unsigned int countersize)
+                                   struct crypto_cipher *tfm)
 {
         unsigned int bsize = crypto_cipher_blocksize(tfm);
-        u8 *keystream = ctrblk + bsize;
+        unsigned long alignmask = crypto_cipher_alignmask(tfm);
+        u8 *ctrblk = walk->iv;
+        u8 tmp[bsize + alignmask];
+        u8 *keystream = PTR_ALIGN(tmp + 0, alignmask + 1);
         u8 *src = walk->src.virt.addr;
         u8 *dst = walk->dst.virt.addr;
         unsigned int nbytes = walk->nbytes;
@@ -72,15 +61,17 @@ static void crypto_ctr_crypt_final(struct blkcipher_walk *walk,
         crypto_cipher_encrypt_one(tfm, keystream, ctrblk);
         crypto_xor(keystream, src, nbytes);
         memcpy(dst, keystream, nbytes);
+
+        crypto_inc(ctrblk, bsize);
 }
 
 static int crypto_ctr_crypt_segment(struct blkcipher_walk *walk,
-                                    struct crypto_cipher *tfm, u8 *ctrblk,
-                                    unsigned int countersize)
+                                    struct crypto_cipher *tfm)
 {
         void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
                    crypto_cipher_alg(tfm)->cia_encrypt;
         unsigned int bsize = crypto_cipher_blocksize(tfm);
+        u8 *ctrblk = walk->iv;
         u8 *src = walk->src.virt.addr;
         u8 *dst = walk->dst.virt.addr;
         unsigned int nbytes = walk->nbytes;
@@ -91,7 +82,7 @@ static int crypto_ctr_crypt_segment(struct blkcipher_walk *walk,
                 crypto_xor(dst, src, bsize);
 
                 /* increment counter in counterblock */
-                crypto_inc(ctrblk + bsize - countersize, countersize);
+                crypto_inc(ctrblk, bsize);
 
                 src += bsize;
                 dst += bsize;
@@ -101,15 +92,17 @@ static int crypto_ctr_crypt_segment(struct blkcipher_walk *walk,
 }
 
 static int crypto_ctr_crypt_inplace(struct blkcipher_walk *walk,
-                                    struct crypto_cipher *tfm, u8 *ctrblk,
-                                    unsigned int countersize)
+                                    struct crypto_cipher *tfm)
 {
         void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
                    crypto_cipher_alg(tfm)->cia_encrypt;
         unsigned int bsize = crypto_cipher_blocksize(tfm);
+        unsigned long alignmask = crypto_cipher_alignmask(tfm);
         unsigned int nbytes = walk->nbytes;
+        u8 *ctrblk = walk->iv;
         u8 *src = walk->src.virt.addr;
-        u8 *keystream = ctrblk + bsize;
+        u8 tmp[bsize + alignmask];
+        u8 *keystream = PTR_ALIGN(tmp + 0, alignmask + 1);
 
         do {
                 /* create keystream */
@@ -117,7 +110,7 @@ static int crypto_ctr_crypt_inplace(struct blkcipher_walk *walk,
                 crypto_xor(src, keystream, bsize);
 
                 /* increment counter in counterblock */
-                crypto_inc(ctrblk + bsize - countersize, countersize);
+                crypto_inc(ctrblk, bsize);
 
                 src += bsize;
         } while ((nbytes -= bsize) >= bsize);
@@ -134,41 +127,22 @@ static int crypto_ctr_crypt(struct blkcipher_desc *desc,
         struct crypto_ctr_ctx *ctx = crypto_blkcipher_ctx(tfm);
         struct crypto_cipher *child = ctx->child;
         unsigned int bsize = crypto_cipher_blocksize(child);
-        struct ctr_instance_ctx *ictx =
-                crypto_instance_ctx(crypto_tfm_alg_instance(&tfm->base));
-        unsigned long alignmask = crypto_cipher_alignmask(child) |
-                                  (__alignof__(u32) - 1);
-        u8 cblk[bsize * 2 + alignmask];
-        u8 *counterblk = (u8 *)ALIGN((unsigned long)cblk, alignmask + 1);
         int err;
 
         blkcipher_walk_init(&walk, dst, src, nbytes);
         err = blkcipher_walk_virt_block(desc, &walk, bsize);
 
-        /* set up counter block */
-        memset(counterblk, 0 , bsize);
-        memcpy(counterblk, ctx->nonce, ictx->noncesize);
-        memcpy(counterblk + ictx->noncesize, walk.iv, ictx->ivsize);
-
-        /* initialize counter portion of counter block */
-        crypto_inc(counterblk + bsize - ictx->countersize, ictx->countersize);
-
         while (walk.nbytes >= bsize) {
                 if (walk.src.virt.addr == walk.dst.virt.addr)
-                        nbytes = crypto_ctr_crypt_inplace(&walk, child,
-                                                          counterblk,
-                                                          ictx->countersize);
+                        nbytes = crypto_ctr_crypt_inplace(&walk, child);
                 else
-                        nbytes = crypto_ctr_crypt_segment(&walk, child,
-                                                          counterblk,
-                                                          ictx->countersize);
+                        nbytes = crypto_ctr_crypt_segment(&walk, child);
 
                 err = blkcipher_walk_done(desc, &walk, nbytes);
         }
 
         if (walk.nbytes) {
-                crypto_ctr_crypt_final(&walk, child, counterblk,
-                                       ictx->countersize);
+                crypto_ctr_crypt_final(&walk, child);
                 err = blkcipher_walk_done(desc, &walk, 0);
         }
 
@@ -178,15 +152,11 @@ static int crypto_ctr_crypt(struct blkcipher_desc *desc,
 static int crypto_ctr_init_tfm(struct crypto_tfm *tfm)
 {
         struct crypto_instance *inst = (void *)tfm->__crt_alg;
-        struct ctr_instance_ctx *ictx = crypto_instance_ctx(inst);
+        struct crypto_spawn *spawn = crypto_instance_ctx(inst);
         struct crypto_ctr_ctx *ctx = crypto_tfm_ctx(tfm);
         struct crypto_cipher *cipher;
 
-        ctx->nonce = kzalloc(ictx->noncesize, GFP_KERNEL);
-        if (!ctx->nonce)
-                return -ENOMEM;
-
-        cipher = crypto_spawn_cipher(&ictx->alg);
+        cipher = crypto_spawn_cipher(spawn);
         if (IS_ERR(cipher))
                 return PTR_ERR(cipher);
 
@@ -199,7 +169,6 @@ static void crypto_ctr_exit_tfm(struct crypto_tfm *tfm)
 {
         struct crypto_ctr_ctx *ctx = crypto_tfm_ctx(tfm);
 
-        kfree(ctx->nonce);
         crypto_free_cipher(ctx->child);
 }
 
@@ -207,10 +176,6 @@ static struct crypto_instance *crypto_ctr_alloc(struct rtattr **tb)
 {
         struct crypto_instance *inst;
         struct crypto_alg *alg;
-        struct ctr_instance_ctx *ictx;
-        unsigned int noncesize;
-        unsigned int ivsize;
-        unsigned int countersize;
         int err;
 
         err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_BLKCIPHER);
@@ -222,71 +187,28 @@ static struct crypto_instance *crypto_ctr_alloc(struct rtattr **tb)
         if (IS_ERR(alg))
                 return ERR_PTR(PTR_ERR(alg));
 
-        err = crypto_attr_u32(tb[2], &noncesize);
-        if (err)
-                goto out_put_alg;
-
-        err = crypto_attr_u32(tb[3], &ivsize);
-        if (err)
-                goto out_put_alg;
-
-        err = crypto_attr_u32(tb[4], &countersize);
-        if (err)
-                goto out_put_alg;
-
-        /* verify size of nonce + iv + counter
-         * counter must be >= 4 bytes.
-         */
+        /* Block size must be >= 4 bytes. */
         err = -EINVAL;
-        if (((noncesize + ivsize + countersize) < alg->cra_blocksize) ||
-            ((noncesize + ivsize) > alg->cra_blocksize) ||
-            (countersize > alg->cra_blocksize) || (countersize < 4))
+        if (alg->cra_blocksize < 4)
                 goto out_put_alg;
 
         /* If this is false we'd fail the alignment of crypto_inc. */
-        if ((alg->cra_blocksize - countersize) % 4)
+        if (alg->cra_blocksize % 4)
                 goto out_put_alg;
 
-        inst = kzalloc(sizeof(*inst) + sizeof(*ictx), GFP_KERNEL);
-        err = -ENOMEM;
-        if (!inst)
-                goto out_put_alg;
-
-        err = -ENAMETOOLONG;
-        if (snprintf(inst->alg.cra_name, CRYPTO_MAX_ALG_NAME,
-                     "ctr(%s,%u,%u,%u)", alg->cra_name, noncesize,
-                     ivsize, countersize) >= CRYPTO_MAX_ALG_NAME) {
-                goto err_free_inst;
-        }
-
-        if (snprintf(inst->alg.cra_driver_name, CRYPTO_MAX_ALG_NAME,
-                     "ctr(%s,%u,%u,%u)", alg->cra_driver_name, noncesize,
-                     ivsize, countersize) >= CRYPTO_MAX_ALG_NAME) {
-                goto err_free_inst;
-        }
-
-        ictx = crypto_instance_ctx(inst);
-        ictx->noncesize = noncesize;
-        ictx->ivsize = ivsize;
-        ictx->countersize = countersize;
-
-        err = crypto_init_spawn(&ictx->alg, alg, inst,
-                CRYPTO_ALG_TYPE_MASK | CRYPTO_ALG_ASYNC);
-        if (err)
-                goto err_free_inst;
+        inst = crypto_alloc_instance("ctr", alg);
+        if (IS_ERR(inst))
+                goto out;
 
-        err = 0;
         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 | (__alignof__(u32) - 1);
         inst->alg.cra_type = &crypto_blkcipher_type;
 
-        inst->alg.cra_blkcipher.ivsize = ivsize;
-        inst->alg.cra_blkcipher.min_keysize = alg->cra_cipher.cia_min_keysize
-                                              + noncesize;
-        inst->alg.cra_blkcipher.max_keysize = alg->cra_cipher.cia_max_keysize
-                                              + noncesize;
+        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);
 
@@ -297,24 +219,18 @@ static struct crypto_instance *crypto_ctr_alloc(struct rtattr **tb)
         inst->alg.cra_blkcipher.encrypt = crypto_ctr_crypt;
         inst->alg.cra_blkcipher.decrypt = crypto_ctr_crypt;
 
-err_free_inst:
-        if (err)
-                kfree(inst);
-
-out_put_alg:
+out:
         crypto_mod_put(alg);
-
-        if (err)
-                inst = ERR_PTR(err);
-
         return inst;
+
+out_put_alg:
+        inst = ERR_PTR(err);
+        goto out;
 }
 
 static void crypto_ctr_free(struct crypto_instance *inst)
 {
-        struct ctr_instance_ctx *ictx = crypto_instance_ctx(inst);
-
-        crypto_drop_spawn(&ictx->alg);
+        crypto_drop_spawn(crypto_instance_ctx(inst));
         kfree(inst);
 }
 
@@ -325,13 +241,174 @@ static struct crypto_template crypto_ctr_tmpl = {
         .module = THIS_MODULE,
 };
 
+static int crypto_rfc3686_setkey(struct crypto_tfm *parent, const u8 *key,
+                                 unsigned int keylen)
+{
+        struct crypto_rfc3686_ctx *ctx = crypto_tfm_ctx(parent);
+        struct crypto_blkcipher *child = ctx->child;
+        int err;
+
+        /* the nonce is stored in bytes at end of key */
+        if (keylen < CTR_RFC3686_NONCE_SIZE)
+                return -EINVAL;
+
+        memcpy(ctx->nonce, key + (keylen - CTR_RFC3686_NONCE_SIZE),
+               CTR_RFC3686_NONCE_SIZE);
+
+        keylen -= CTR_RFC3686_NONCE_SIZE;
+
+        crypto_blkcipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
+        crypto_blkcipher_set_flags(child, crypto_tfm_get_flags(parent) &
+                                          CRYPTO_TFM_REQ_MASK);
+        err = crypto_blkcipher_setkey(child, key, keylen);
+        crypto_tfm_set_flags(parent, crypto_blkcipher_get_flags(child) &
+                                     CRYPTO_TFM_RES_MASK);
+
+        return err;
+}
+
+static int crypto_rfc3686_crypt(struct blkcipher_desc *desc,
+                                struct scatterlist *dst,
+                                struct scatterlist *src, unsigned int nbytes)
+{
+        struct crypto_blkcipher *tfm = desc->tfm;
+        struct crypto_rfc3686_ctx *ctx = crypto_blkcipher_ctx(tfm);
+        struct crypto_blkcipher *child = ctx->child;
+        unsigned long alignmask = crypto_blkcipher_alignmask(tfm);
+        u8 ivblk[CTR_RFC3686_BLOCK_SIZE + alignmask];
+        u8 *iv = PTR_ALIGN(ivblk + 0, alignmask + 1);
+        u8 *info = desc->info;
+        int err;
+
+        /* set up counter block */
+        memcpy(iv, ctx->nonce, CTR_RFC3686_NONCE_SIZE);
+        memcpy(iv + CTR_RFC3686_NONCE_SIZE, info, CTR_RFC3686_IV_SIZE);
+
+        /* initialize counter portion of counter block */
+        *(__be32 *)(iv + CTR_RFC3686_NONCE_SIZE + CTR_RFC3686_IV_SIZE) =
+                cpu_to_be32(1);
+
+        desc->tfm = child;
+        desc->info = iv;
+        err = crypto_blkcipher_encrypt_iv(desc, dst, src, nbytes);
+        desc->tfm = tfm;
+        desc->info = info;
+
+        return err;
+}
+
+static int crypto_rfc3686_init_tfm(struct crypto_tfm *tfm)
+{
+        struct crypto_instance *inst = (void *)tfm->__crt_alg;
+        struct crypto_spawn *spawn = crypto_instance_ctx(inst);
+        struct crypto_rfc3686_ctx *ctx = crypto_tfm_ctx(tfm);
+        struct crypto_blkcipher *cipher;
+
+        cipher = crypto_spawn_blkcipher(spawn);
+        if (IS_ERR(cipher))
+                return PTR_ERR(cipher);
+
+        ctx->child = cipher;
+
+        return 0;
+}
+
+static void crypto_rfc3686_exit_tfm(struct crypto_tfm *tfm)
+{
+        struct crypto_rfc3686_ctx *ctx = crypto_tfm_ctx(tfm);
+
+        crypto_free_blkcipher(ctx->child);
+}
+
+static struct crypto_instance *crypto_rfc3686_alloc(struct rtattr **tb)
+{
+        struct crypto_instance *inst;
+        struct crypto_alg *alg;
+        int err;
+
+        err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_BLKCIPHER);
+        if (err)
+                return ERR_PTR(err);
+
+        alg = crypto_attr_alg(tb[1], CRYPTO_ALG_TYPE_BLKCIPHER,
+                                  CRYPTO_ALG_TYPE_MASK);
+        err = PTR_ERR(alg);
+        if (IS_ERR(alg))
+                return ERR_PTR(err);
+
+        /* We only support 16-byte blocks. */
+        err = -EINVAL;
+        if (alg->cra_blkcipher.ivsize != CTR_RFC3686_BLOCK_SIZE)
+                goto out_put_alg;
+
+        /* Not a stream cipher? */
+        if (alg->cra_blocksize != 1)
+                goto out_put_alg;
+
+        inst = crypto_alloc_instance("rfc3686", 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;
+
+        inst->alg.cra_blkcipher.ivsize = CTR_RFC3686_IV_SIZE;
+        inst->alg.cra_blkcipher.min_keysize = alg->cra_blkcipher.min_keysize
+                                              + CTR_RFC3686_NONCE_SIZE;
+        inst->alg.cra_blkcipher.max_keysize = alg->cra_blkcipher.max_keysize
+                                              + CTR_RFC3686_NONCE_SIZE;
+
+        inst->alg.cra_ctxsize = sizeof(struct crypto_rfc3686_ctx);
+
+        inst->alg.cra_init = crypto_rfc3686_init_tfm;
+        inst->alg.cra_exit = crypto_rfc3686_exit_tfm;
+
+        inst->alg.cra_blkcipher.setkey = crypto_rfc3686_setkey;
+        inst->alg.cra_blkcipher.encrypt = crypto_rfc3686_crypt;
+        inst->alg.cra_blkcipher.decrypt = crypto_rfc3686_crypt;
+
+out:
+        crypto_mod_put(alg);
+        return inst;
+
+out_put_alg:
+        inst = ERR_PTR(err);
+        goto out;
+}
+
+static struct crypto_template crypto_rfc3686_tmpl = {
+        .name = "rfc3686",
+        .alloc = crypto_rfc3686_alloc,
+        .free = crypto_ctr_free,
+        .module = THIS_MODULE,
+};
+
 static int __init crypto_ctr_module_init(void)
 {
-        return crypto_register_template(&crypto_ctr_tmpl);
+        int err;
+
+        err = crypto_register_template(&crypto_ctr_tmpl);
+        if (err)
+                goto out;
+
+        err = crypto_register_template(&crypto_rfc3686_tmpl);
+        if (err)
+                goto out_drop_ctr;
+
+out:
+        return err;
+
+out_drop_ctr:
+        crypto_unregister_template(&crypto_ctr_tmpl);
+        goto out;
 }
 
 static void __exit crypto_ctr_module_exit(void)
 {
+        crypto_unregister_template(&crypto_rfc3686_tmpl);
         crypto_unregister_template(&crypto_ctr_tmpl);
 }
 
@@ -340,3 +417,4 @@ module_exit(crypto_ctr_module_exit);
 
 MODULE_LICENSE("GPL");
 MODULE_DESCRIPTION("CTR Counter block mode");
+MODULE_ALIAS("rfc3686");