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-rw-r--r--crypto/cbc.c223
1 files changed, 223 insertions, 0 deletions
diff --git a/crypto/cbc.c b/crypto/cbc.c
new file mode 100644
index 000000000..6c03e96b9
--- /dev/null
+++ b/crypto/cbc.c
@@ -0,0 +1,223 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * CBC: Cipher Block Chaining mode
+ *
+ * Copyright (c) 2006-2016 Herbert Xu <herbert@gondor.apana.org.au>
+ */
+
+#include <crypto/algapi.h>
+#include <crypto/internal/cipher.h>
+#include <crypto/internal/skcipher.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/log2.h>
+#include <linux/module.h>
+
+static int crypto_cbc_encrypt_segment(struct skcipher_walk *walk,
+ struct crypto_skcipher *skcipher)
+{
+ unsigned int bsize = crypto_skcipher_blocksize(skcipher);
+ void (*fn)(struct crypto_tfm *, u8 *, const u8 *);
+ unsigned int nbytes = walk->nbytes;
+ u8 *src = walk->src.virt.addr;
+ u8 *dst = walk->dst.virt.addr;
+ struct crypto_cipher *cipher;
+ struct crypto_tfm *tfm;
+ u8 *iv = walk->iv;
+
+ cipher = skcipher_cipher_simple(skcipher);
+ tfm = crypto_cipher_tfm(cipher);
+ fn = crypto_cipher_alg(cipher)->cia_encrypt;
+
+ do {
+ crypto_xor(iv, src, bsize);
+ fn(tfm, dst, iv);
+ memcpy(iv, dst, bsize);
+
+ src += bsize;
+ dst += bsize;
+ } while ((nbytes -= bsize) >= bsize);
+
+ return nbytes;
+}
+
+static int crypto_cbc_encrypt_inplace(struct skcipher_walk *walk,
+ struct crypto_skcipher *skcipher)
+{
+ unsigned int bsize = crypto_skcipher_blocksize(skcipher);
+ void (*fn)(struct crypto_tfm *, u8 *, const u8 *);
+ unsigned int nbytes = walk->nbytes;
+ u8 *src = walk->src.virt.addr;
+ struct crypto_cipher *cipher;
+ struct crypto_tfm *tfm;
+ u8 *iv = walk->iv;
+
+ cipher = skcipher_cipher_simple(skcipher);
+ tfm = crypto_cipher_tfm(cipher);
+ fn = crypto_cipher_alg(cipher)->cia_encrypt;
+
+ do {
+ crypto_xor(src, iv, bsize);
+ fn(tfm, src, src);
+ iv = src;
+
+ src += bsize;
+ } while ((nbytes -= bsize) >= bsize);
+
+ memcpy(walk->iv, iv, bsize);
+
+ return nbytes;
+}
+
+static int crypto_cbc_encrypt(struct skcipher_request *req)
+{
+ struct crypto_skcipher *skcipher = crypto_skcipher_reqtfm(req);
+ struct skcipher_walk walk;
+ int err;
+
+ err = skcipher_walk_virt(&walk, req, false);
+
+ while (walk.nbytes) {
+ if (walk.src.virt.addr == walk.dst.virt.addr)
+ err = crypto_cbc_encrypt_inplace(&walk, skcipher);
+ else
+ err = crypto_cbc_encrypt_segment(&walk, skcipher);
+ err = skcipher_walk_done(&walk, err);
+ }
+
+ return err;
+}
+
+static int crypto_cbc_decrypt_segment(struct skcipher_walk *walk,
+ struct crypto_skcipher *skcipher)
+{
+ unsigned int bsize = crypto_skcipher_blocksize(skcipher);
+ void (*fn)(struct crypto_tfm *, u8 *, const u8 *);
+ unsigned int nbytes = walk->nbytes;
+ u8 *src = walk->src.virt.addr;
+ u8 *dst = walk->dst.virt.addr;
+ struct crypto_cipher *cipher;
+ struct crypto_tfm *tfm;
+ u8 *iv = walk->iv;
+
+ cipher = skcipher_cipher_simple(skcipher);
+ tfm = crypto_cipher_tfm(cipher);
+ fn = crypto_cipher_alg(cipher)->cia_decrypt;
+
+ do {
+ fn(tfm, dst, src);
+ crypto_xor(dst, iv, bsize);
+ iv = src;
+
+ src += bsize;
+ dst += bsize;
+ } while ((nbytes -= bsize) >= bsize);
+
+ memcpy(walk->iv, iv, bsize);
+
+ return nbytes;
+}
+
+static int crypto_cbc_decrypt_inplace(struct skcipher_walk *walk,
+ struct crypto_skcipher *skcipher)
+{
+ unsigned int bsize = crypto_skcipher_blocksize(skcipher);
+ void (*fn)(struct crypto_tfm *, u8 *, const u8 *);
+ unsigned int nbytes = walk->nbytes;
+ u8 *src = walk->src.virt.addr;
+ u8 last_iv[MAX_CIPHER_BLOCKSIZE];
+ struct crypto_cipher *cipher;
+ struct crypto_tfm *tfm;
+
+ cipher = skcipher_cipher_simple(skcipher);
+ tfm = crypto_cipher_tfm(cipher);
+ fn = crypto_cipher_alg(cipher)->cia_decrypt;
+
+ /* Start of the last block. */
+ src += nbytes - (nbytes & (bsize - 1)) - bsize;
+ memcpy(last_iv, src, bsize);
+
+ for (;;) {
+ fn(tfm, src, src);
+ if ((nbytes -= bsize) < bsize)
+ break;
+ crypto_xor(src, src - bsize, bsize);
+ src -= bsize;
+ }
+
+ crypto_xor(src, walk->iv, bsize);
+ memcpy(walk->iv, last_iv, bsize);
+
+ return nbytes;
+}
+
+static int crypto_cbc_decrypt(struct skcipher_request *req)
+{
+ struct crypto_skcipher *skcipher = crypto_skcipher_reqtfm(req);
+ struct skcipher_walk walk;
+ int err;
+
+ err = skcipher_walk_virt(&walk, req, false);
+
+ while (walk.nbytes) {
+ if (walk.src.virt.addr == walk.dst.virt.addr)
+ err = crypto_cbc_decrypt_inplace(&walk, skcipher);
+ else
+ err = crypto_cbc_decrypt_segment(&walk, skcipher);
+ err = skcipher_walk_done(&walk, err);
+ }
+
+ return err;
+}
+
+static int crypto_cbc_create(struct crypto_template *tmpl, struct rtattr **tb)
+{
+ struct skcipher_instance *inst;
+ struct crypto_alg *alg;
+ int err;
+
+ inst = skcipher_alloc_instance_simple(tmpl, tb);
+ if (IS_ERR(inst))
+ return PTR_ERR(inst);
+
+ alg = skcipher_ialg_simple(inst);
+
+ err = -EINVAL;
+ if (!is_power_of_2(alg->cra_blocksize))
+ goto out_free_inst;
+
+ inst->alg.encrypt = crypto_cbc_encrypt;
+ inst->alg.decrypt = crypto_cbc_decrypt;
+
+ err = skcipher_register_instance(tmpl, inst);
+ if (err) {
+out_free_inst:
+ inst->free(inst);
+ }
+
+ return err;
+}
+
+static struct crypto_template crypto_cbc_tmpl = {
+ .name = "cbc",
+ .create = crypto_cbc_create,
+ .module = THIS_MODULE,
+};
+
+static int __init crypto_cbc_module_init(void)
+{
+ return crypto_register_template(&crypto_cbc_tmpl);
+}
+
+static void __exit crypto_cbc_module_exit(void)
+{
+ crypto_unregister_template(&crypto_cbc_tmpl);
+}
+
+subsys_initcall(crypto_cbc_module_init);
+module_exit(crypto_cbc_module_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("CBC block cipher mode of operation");
+MODULE_ALIAS_CRYPTO("cbc");