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authorGilad Ben-Yossef <gilad@benyossef.com>2018-09-20 14:18:39 +0100
committerHerbert Xu <herbert@gondor.apana.org.au>2018-09-28 12:46:26 +0800
commite497c51896b3babfb14a36e497fd36a15f56cfa4 (patch)
treef8f77c55ceea579c373c7b08c15ebfdbb714771e /crypto
parent95ba597367ddc26c1062c7ee9697c9aee53d04d0 (diff)
downloadlinux-stericsson-e497c51896b3babfb14a36e497fd36a15f56cfa4.tar.gz
crypto: ofb - add output feedback mode
Add a generic version of output feedback mode. We already have support of several hardware based transformations of this mode and the needed test vectors but we somehow missed adding a generic software one. Fix this now. Signed-off-by: Gilad Ben-Yossef <gilad@benyossef.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Diffstat (limited to 'crypto')
-rw-r--r--crypto/Kconfig12
-rw-r--r--crypto/Makefile1
-rw-r--r--crypto/ofb.c225
3 files changed, 238 insertions, 0 deletions
diff --git a/crypto/Kconfig b/crypto/Kconfig
index 4ef95b0b25a3..63ef279322d2 100644
--- a/crypto/Kconfig
+++ b/crypto/Kconfig
@@ -456,6 +456,18 @@ config CRYPTO_LRW
The first 128, 192 or 256 bits in the key are used for AES and the
rest is used to tie each cipher block to its logical position.
+config CRYPTO_OFB
+ tristate "OFB support"
+ select CRYPTO_BLKCIPHER
+ select CRYPTO_MANAGER
+ help
+ OFB: the Output Feedback mode makes a block cipher into a synchronous
+ stream cipher. It generates keystream blocks, which are then XORed
+ with the plaintext blocks to get the ciphertext. Flipping a bit in the
+ ciphertext produces a flipped bit in the plaintext at the same
+ location. This property allows many error correcting codes to function
+ normally even when applied before encryption.
+
config CRYPTO_PCBC
tristate "PCBC support"
select CRYPTO_BLKCIPHER
diff --git a/crypto/Makefile b/crypto/Makefile
index ff5c2bbda04a..5c207c76abf7 100644
--- a/crypto/Makefile
+++ b/crypto/Makefile
@@ -142,6 +142,7 @@ obj-$(CONFIG_CRYPTO_USER_API_SKCIPHER) += algif_skcipher.o
obj-$(CONFIG_CRYPTO_USER_API_RNG) += algif_rng.o
obj-$(CONFIG_CRYPTO_USER_API_AEAD) += algif_aead.o
obj-$(CONFIG_CRYPTO_ZSTD) += zstd.o
+obj-$(CONFIG_CRYPTO_OFB) += ofb.o
ecdh_generic-y := ecc.o
ecdh_generic-y += ecdh.o
diff --git a/crypto/ofb.c b/crypto/ofb.c
new file mode 100644
index 000000000000..886631708c5e
--- /dev/null
+++ b/crypto/ofb.c
@@ -0,0 +1,225 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * OFB: Output FeedBack mode
+ *
+ * Copyright (C) 2018 ARM Limited or its affiliates.
+ * All rights reserved.
+ *
+ * Based loosely on public domain code gleaned from libtomcrypt
+ * (https://github.com/libtom/libtomcrypt).
+ */
+
+#include <crypto/algapi.h>
+#include <crypto/internal/skcipher.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/scatterlist.h>
+#include <linux/slab.h>
+
+struct crypto_ofb_ctx {
+ struct crypto_cipher *child;
+ int cnt;
+};
+
+
+static int crypto_ofb_setkey(struct crypto_skcipher *parent, const u8 *key,
+ unsigned int keylen)
+{
+ struct crypto_ofb_ctx *ctx = crypto_skcipher_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_skcipher_get_flags(parent) &
+ CRYPTO_TFM_REQ_MASK);
+ err = crypto_cipher_setkey(child, key, keylen);
+ crypto_skcipher_set_flags(parent, crypto_cipher_get_flags(child) &
+ CRYPTO_TFM_RES_MASK);
+ return err;
+}
+
+static int crypto_ofb_encrypt_segment(struct crypto_ofb_ctx *ctx,
+ struct skcipher_walk *walk,
+ struct crypto_cipher *tfm)
+{
+ int bsize = crypto_cipher_blocksize(tfm);
+ int nbytes = walk->nbytes;
+
+ u8 *src = walk->src.virt.addr;
+ u8 *dst = walk->dst.virt.addr;
+ u8 *iv = walk->iv;
+
+ do {
+ if (ctx->cnt == bsize) {
+ if (nbytes < bsize)
+ break;
+ crypto_cipher_encrypt_one(tfm, iv, iv);
+ ctx->cnt = 0;
+ }
+ *dst = *src ^ iv[ctx->cnt];
+ src++;
+ dst++;
+ ctx->cnt++;
+ } while (--nbytes);
+ return nbytes;
+}
+
+static int crypto_ofb_encrypt(struct skcipher_request *req)
+{
+ struct skcipher_walk walk;
+ struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
+ unsigned int bsize;
+ struct crypto_ofb_ctx *ctx = crypto_skcipher_ctx(tfm);
+ struct crypto_cipher *child = ctx->child;
+ int ret = 0;
+
+ bsize = crypto_cipher_blocksize(child);
+ ctx->cnt = bsize;
+
+ ret = skcipher_walk_virt(&walk, req, false);
+
+ while (walk.nbytes) {
+ ret = crypto_ofb_encrypt_segment(ctx, &walk, child);
+ ret = skcipher_walk_done(&walk, ret);
+ }
+
+ return ret;
+}
+
+/* OFB encrypt and decrypt are identical */
+static int crypto_ofb_decrypt(struct skcipher_request *req)
+{
+ return crypto_ofb_encrypt(req);
+}
+
+static int crypto_ofb_init_tfm(struct crypto_skcipher *tfm)
+{
+ struct skcipher_instance *inst = skcipher_alg_instance(tfm);
+ struct crypto_spawn *spawn = skcipher_instance_ctx(inst);
+ struct crypto_ofb_ctx *ctx = crypto_skcipher_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_ofb_exit_tfm(struct crypto_skcipher *tfm)
+{
+ struct crypto_ofb_ctx *ctx = crypto_skcipher_ctx(tfm);
+
+ crypto_free_cipher(ctx->child);
+}
+
+static void crypto_ofb_free(struct skcipher_instance *inst)
+{
+ crypto_drop_skcipher(skcipher_instance_ctx(inst));
+ kfree(inst);
+}
+
+static int crypto_ofb_create(struct crypto_template *tmpl, struct rtattr **tb)
+{
+ struct skcipher_instance *inst;
+ struct crypto_attr_type *algt;
+ struct crypto_spawn *spawn;
+ struct crypto_alg *alg;
+ u32 mask;
+ int err;
+
+ err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SKCIPHER);
+ if (err)
+ return err;
+
+ inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL);
+ if (!inst)
+ return -ENOMEM;
+
+ algt = crypto_get_attr_type(tb);
+ err = PTR_ERR(algt);
+ if (IS_ERR(algt))
+ goto err_free_inst;
+
+ mask = CRYPTO_ALG_TYPE_MASK |
+ crypto_requires_off(algt->type, algt->mask,
+ CRYPTO_ALG_NEED_FALLBACK);
+
+ alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER, mask);
+ err = PTR_ERR(alg);
+ if (IS_ERR(alg))
+ goto err_free_inst;
+
+ spawn = skcipher_instance_ctx(inst);
+ err = crypto_init_spawn(spawn, alg, skcipher_crypto_instance(inst),
+ CRYPTO_ALG_TYPE_MASK);
+ crypto_mod_put(alg);
+ if (err)
+ goto err_free_inst;
+
+ err = crypto_inst_setname(skcipher_crypto_instance(inst), "ofb", alg);
+ if (err)
+ goto err_drop_spawn;
+
+ inst->alg.base.cra_priority = alg->cra_priority;
+ inst->alg.base.cra_blocksize = alg->cra_blocksize;
+ inst->alg.base.cra_alignmask = alg->cra_alignmask;
+
+ /* We access the data as u32s when xoring. */
+ inst->alg.base.cra_alignmask |= __alignof__(u32) - 1;
+
+ inst->alg.ivsize = alg->cra_blocksize;
+ inst->alg.min_keysize = alg->cra_cipher.cia_min_keysize;
+ inst->alg.max_keysize = alg->cra_cipher.cia_max_keysize;
+
+ inst->alg.base.cra_ctxsize = sizeof(struct crypto_ofb_ctx);
+
+ inst->alg.init = crypto_ofb_init_tfm;
+ inst->alg.exit = crypto_ofb_exit_tfm;
+
+ inst->alg.setkey = crypto_ofb_setkey;
+ inst->alg.encrypt = crypto_ofb_encrypt;
+ inst->alg.decrypt = crypto_ofb_decrypt;
+
+ inst->free = crypto_ofb_free;
+
+ err = skcipher_register_instance(tmpl, inst);
+ if (err)
+ goto err_drop_spawn;
+
+out:
+ return err;
+
+err_drop_spawn:
+ crypto_drop_spawn(spawn);
+err_free_inst:
+ kfree(inst);
+ goto out;
+}
+
+static struct crypto_template crypto_ofb_tmpl = {
+ .name = "ofb",
+ .create = crypto_ofb_create,
+ .module = THIS_MODULE,
+};
+
+static int __init crypto_ofb_module_init(void)
+{
+ return crypto_register_template(&crypto_ofb_tmpl);
+}
+
+static void __exit crypto_ofb_module_exit(void)
+{
+ crypto_unregister_template(&crypto_ofb_tmpl);
+}
+
+module_init(crypto_ofb_module_init);
+module_exit(crypto_ofb_module_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("OFB block cipher algorithm");
+MODULE_ALIAS_CRYPTO("ofb");