--- /dev/null
+/*
+ * CTR: Counter mode
+ *
+ * (C) Copyright IBM Corp. 2007 - Joy Latten <latten@us.ibm.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ *
+ */
+
+#include <crypto/algapi.h>
+#include <linux/err.h>
+#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 ctr_instance_ctx {
+ struct crypto_spawn alg;
+ unsigned int noncesize;
+ unsigned int ivsize;
+};
+
+struct crypto_ctr_ctx {
+ struct crypto_cipher *child;
+ u8 *nonce;
+};
+
+static inline void __ctr_inc_byte(u8 *a, unsigned int size)
+{
+ u8 *b = (a + size);
+ u8 c;
+
+ for (; size; size--) {
+ c = *--b + 1;
+ *b = c;
+ if (c)
+ break;
+ }
+}
+
+static void ctr_inc_quad(u8 *a, unsigned int size)
+{
+ __be32 *b = (__be32 *)(a + size);
+ u32 c;
+
+ for (; size >= 4; size -=4) {
+ c = be32_to_cpu(*--b) + 1;
+ *b = cpu_to_be32(c);
+ if (c)
+ return;
+ }
+
+ __ctr_inc_byte(a, size);
+}
+
+static void xor_byte(u8 *a, const u8 *b, unsigned int bs)
+{
+ for (; bs; bs--)
+ *a++ ^= *b++;
+}
+
+static void xor_quad(u8 *dst, const u8 *src, unsigned int bs)
+{
+ u32 *a = (u32 *)dst;
+ u32 *b = (u32 *)src;
+
+ for (; bs >= 4; bs -= 4)
+ *a++ ^= *b++;
+
+ xor_byte((u8 *)a, (u8 *)b, bs);
+}
+
+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;
+ 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;
+
+ 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 int crypto_ctr_crypt_segment(struct blkcipher_walk *walk,
+ struct crypto_cipher *tfm, u8 *ctrblk,
+ unsigned int countersize)
+{
+ 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);
+ u8 ks[bsize + alignmask];
+ u8 *keystream = (u8 *)ALIGN((unsigned long)ks, alignmask + 1);
+ u8 *src = walk->src.virt.addr;
+ u8 *dst = walk->dst.virt.addr;
+ unsigned int nbytes = walk->nbytes;
+
+ do {
+ /* create keystream */
+ fn(crypto_cipher_tfm(tfm), keystream, ctrblk);
+ xor_quad(keystream, src, min(nbytes, bsize));
+
+ /* copy result into dst */
+ memcpy(dst, keystream, min(nbytes, bsize));
+
+ /* increment counter in counterblock */
+ ctr_inc_quad(ctrblk + (bsize - countersize), countersize);
+
+ if (nbytes < bsize)
+ break;
+
+ src += bsize;
+ dst += bsize;
+ nbytes -= bsize;
+
+ } while (nbytes);
+
+ return 0;
+}
+
+static int crypto_ctr_crypt_inplace(struct blkcipher_walk *walk,
+ struct crypto_cipher *tfm, u8 *ctrblk,
+ unsigned int countersize)
+{
+ 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 *src = walk->src.virt.addr;
+ u8 ks[bsize + alignmask];
+ u8 *keystream = (u8 *)ALIGN((unsigned long)ks, alignmask + 1);
+
+ do {
+ /* create keystream */
+ fn(crypto_cipher_tfm(tfm), keystream, ctrblk);
+ xor_quad(src, keystream, min(nbytes, bsize));
+
+ /* increment counter in counterblock */
+ ctr_inc_quad(ctrblk + (bsize - countersize), countersize);
+
+ if (nbytes < bsize)
+ break;
+
+ src += bsize;
+ nbytes -= bsize;
+
+ } while (nbytes);
+
+ return 0;
+}
+
+static int crypto_ctr_crypt(struct blkcipher_desc *desc,
+ struct scatterlist *dst, struct scatterlist *src,
+ unsigned int nbytes)
+{
+ 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 ctr_instance_ctx *ictx =
+ crypto_instance_ctx(crypto_tfm_alg_instance(&tfm->base));
+ unsigned long alignmask = crypto_cipher_alignmask(child);
+ u8 cblk[bsize + alignmask];
+ u8 *counterblk = (u8 *)ALIGN((unsigned long)cblk, alignmask + 1);
+ unsigned int countersize;
+ 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 */
+ countersize = bsize - ictx->noncesize - ictx->ivsize;
+ ctr_inc_quad(counterblk + (bsize - countersize), countersize);
+
+ while (walk.nbytes) {
+ if (walk.src.virt.addr == walk.dst.virt.addr)
+ nbytes = crypto_ctr_crypt_inplace(&walk, child,
+ counterblk,
+ countersize);
+ else
+ nbytes = crypto_ctr_crypt_segment(&walk, child,
+ counterblk,
+ countersize);
+
+ err = blkcipher_walk_done(desc, &walk, nbytes);
+ }
+ return err;
+}
+
+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_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);
+ 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);
+
+ kfree(ctx->nonce);
+ crypto_free_cipher(ctx->child);
+}
+
+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;
+ 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_CIPHER,
+ CRYPTO_ALG_TYPE_MASK);
+ 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;
+
+ /* verify size of nonce + iv + counter */
+ err = -EINVAL;
+ if ((noncesize + ivsize) >= alg->cra_blocksize)
+ 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)", alg->cra_name, noncesize,
+ ivsize) >= CRYPTO_MAX_ALG_NAME) {
+ goto err_free_inst;
+ }
+
+ if (snprintf(inst->alg.cra_driver_name, CRYPTO_MAX_ALG_NAME,
+ "ctr(%s,%u,%u)", alg->cra_driver_name, noncesize,
+ ivsize) >= CRYPTO_MAX_ALG_NAME) {
+ goto err_free_inst;
+ }
+
+ ictx = crypto_instance_ctx(inst);
+ ictx->noncesize = noncesize;
+ ictx->ivsize = ivsize;
+
+ err = crypto_init_spawn(&ictx->alg, alg, inst,
+ CRYPTO_ALG_TYPE_MASK | CRYPTO_ALG_ASYNC);
+ if (err)
+ goto err_free_inst;
+
+ 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 = 3;
+ 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_ctxsize = sizeof(struct crypto_ctr_ctx);
+
+ inst->alg.cra_init = crypto_ctr_init_tfm;
+ inst->alg.cra_exit = crypto_ctr_exit_tfm;
+
+ inst->alg.cra_blkcipher.setkey = crypto_ctr_setkey;
+ 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:
+ crypto_mod_put(alg);
+
+ if (err)
+ inst = ERR_PTR(err);
+
+ return inst;
+}
+
+static void crypto_ctr_free(struct crypto_instance *inst)
+{
+ struct ctr_instance_ctx *ictx = crypto_instance_ctx(inst);
+
+ crypto_drop_spawn(&ictx->alg);
+ kfree(inst);
+}
+
+static struct crypto_template crypto_ctr_tmpl = {
+ .name = "ctr",
+ .alloc = crypto_ctr_alloc,
+ .free = crypto_ctr_free,
+ .module = THIS_MODULE,
+};
+
+static int __init crypto_ctr_module_init(void)
+{
+ return crypto_register_template(&crypto_ctr_tmpl);
+}
+
+static void __exit crypto_ctr_module_exit(void)
+{
+ crypto_unregister_template(&crypto_ctr_tmpl);
+}
+
+module_init(crypto_ctr_module_init);
+module_exit(crypto_ctr_module_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("CTR Counter block mode");
git.openpandora.org / pandora-kernel.git / blobdiff