[CRYPTO] seqiv: Add Sequence Number IV Generator
This generator generates an IV based on a sequence number by xoring it
with a salt. This algorithm is mainly useful for CTR and similar modes.
This patch also sets it as the default IV generator for ctr.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
diff --git a/crypto/Kconfig b/crypto/Kconfig
index c4b6c91..7ad9711 100644
--- a/crypto/Kconfig
+++ b/crypto/Kconfig
@@ -32,6 +32,14 @@
tristate
select CRYPTO_ALGAPI
+config CRYPTO_SEQIV
+ tristate "Sequence Number IV Generator"
+ select CRYPTO_BLKCIPHER
+ help
+ This IV generator generates an IV based on a sequence number by
+ xoring it with a salt. This algorithm is mainly useful for CTR
+ and similar modes.
+
config CRYPTO_HASH
tristate
select CRYPTO_ALGAPI
@@ -197,6 +205,7 @@
config CRYPTO_CTR
tristate "CTR support"
select CRYPTO_BLKCIPHER
+ select CRYPTO_SEQIV
select CRYPTO_MANAGER
help
CTR: Counter mode
diff --git a/crypto/Makefile b/crypto/Makefile
index 968b796..1b99b3a 100644
--- a/crypto/Makefile
+++ b/crypto/Makefile
@@ -15,6 +15,7 @@
obj-$(CONFIG_CRYPTO_BLKCIPHER) += crypto_blkcipher.o
obj-$(CONFIG_CRYPTO_BLKCIPHER) += chainiv.o
obj-$(CONFIG_CRYPTO_BLKCIPHER) += eseqiv.o
+obj-$(CONFIG_CRYPTO_SEQIV) += seqiv.o
crypto_hash-objs := hash.o
obj-$(CONFIG_CRYPTO_HASH) += crypto_hash.o
diff --git a/crypto/ctr.c b/crypto/ctr.c
index 1052b31..2d7425f 100644
--- a/crypto/ctr.c
+++ b/crypto/ctr.c
@@ -361,6 +361,8 @@
inst->alg.cra_blkcipher.max_keysize = alg->cra_blkcipher.max_keysize
+ CTR_RFC3686_NONCE_SIZE;
+ inst->alg.cra_blkcipher.geniv = "seqiv";
+
inst->alg.cra_ctxsize = sizeof(struct crypto_rfc3686_ctx);
inst->alg.cra_init = crypto_rfc3686_init_tfm;
diff --git a/crypto/seqiv.c b/crypto/seqiv.c
new file mode 100644
index 0000000..9c2d80d
--- /dev/null
+++ b/crypto/seqiv.c
@@ -0,0 +1,186 @@
+/*
+ * seqiv: Sequence Number IV Generator
+ *
+ * This generator generates an IV based on a sequence number by xoring it
+ * with a salt. This algorithm is mainly useful for CTR and similar modes.
+ *
+ * Copyright (c) 2007 Herbert Xu <herbert@gondor.apana.org.au>
+ *
+ * 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/internal/skcipher.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/random.h>
+#include <linux/spinlock.h>
+#include <linux/string.h>
+
+struct seqiv_ctx {
+ spinlock_t lock;
+ u8 salt[] __attribute__ ((aligned(__alignof__(u32))));
+};
+
+static void seqiv_complete2(struct skcipher_givcrypt_request *req, int err)
+{
+ struct ablkcipher_request *subreq = skcipher_givcrypt_reqctx(req);
+ struct crypto_ablkcipher *geniv;
+
+ if (err == -EINPROGRESS)
+ return;
+
+ if (err)
+ goto out;
+
+ geniv = skcipher_givcrypt_reqtfm(req);
+ memcpy(req->creq.info, subreq->info, crypto_ablkcipher_ivsize(geniv));
+
+out:
+ kfree(subreq->info);
+}
+
+static void seqiv_complete(struct crypto_async_request *base, int err)
+{
+ struct skcipher_givcrypt_request *req = base->data;
+
+ seqiv_complete2(req, err);
+ skcipher_givcrypt_complete(req, err);
+}
+
+static int seqiv_givencrypt(struct skcipher_givcrypt_request *req)
+{
+ struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
+ struct seqiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
+ struct ablkcipher_request *subreq = skcipher_givcrypt_reqctx(req);
+ crypto_completion_t complete;
+ void *data;
+ u8 *info;
+ __be64 seq;
+ unsigned int ivsize;
+ unsigned int len;
+ int err;
+
+ ablkcipher_request_set_tfm(subreq, skcipher_geniv_cipher(geniv));
+
+ complete = req->creq.base.complete;
+ data = req->creq.base.data;
+ info = req->creq.info;
+
+ ivsize = crypto_ablkcipher_ivsize(geniv);
+
+ if (unlikely(!IS_ALIGNED((unsigned long)info,
+ crypto_ablkcipher_alignmask(geniv) + 1))) {
+ info = kmalloc(ivsize, req->creq.base.flags &
+ CRYPTO_TFM_REQ_MAY_SLEEP ? GFP_KERNEL:
+ GFP_ATOMIC);
+ if (!info)
+ return -ENOMEM;
+
+ complete = seqiv_complete;
+ data = req;
+ }
+
+ ablkcipher_request_set_callback(subreq, req->creq.base.flags, complete,
+ data);
+ ablkcipher_request_set_crypt(subreq, req->creq.src, req->creq.dst,
+ req->creq.nbytes, info);
+
+ len = ivsize;
+ if (ivsize > sizeof(u64)) {
+ memset(info, 0, ivsize - sizeof(u64));
+ len = sizeof(u64);
+ }
+ seq = cpu_to_be64(req->seq);
+ memcpy(info + ivsize - len, &seq, len);
+ crypto_xor(info, ctx->salt, ivsize);
+
+ memcpy(req->giv, info, ivsize);
+
+ err = crypto_ablkcipher_encrypt(subreq);
+ if (unlikely(info != req->creq.info))
+ seqiv_complete2(req, err);
+ return err;
+}
+
+static int seqiv_givencrypt_first(struct skcipher_givcrypt_request *req)
+{
+ struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
+ struct seqiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
+
+ spin_lock_bh(&ctx->lock);
+ if (crypto_ablkcipher_crt(geniv)->givencrypt != seqiv_givencrypt_first)
+ goto unlock;
+
+ crypto_ablkcipher_crt(geniv)->givencrypt = seqiv_givencrypt;
+ get_random_bytes(ctx->salt, crypto_ablkcipher_ivsize(geniv));
+
+unlock:
+ spin_unlock_bh(&ctx->lock);
+
+ return seqiv_givencrypt(req);
+}
+
+static int seqiv_init(struct crypto_tfm *tfm)
+{
+ struct crypto_ablkcipher *geniv = __crypto_ablkcipher_cast(tfm);
+ struct seqiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
+
+ spin_lock_init(&ctx->lock);
+
+ tfm->crt_ablkcipher.reqsize = sizeof(struct ablkcipher_request);
+
+ return skcipher_geniv_init(tfm);
+}
+
+static struct crypto_template seqiv_tmpl;
+
+static struct crypto_instance *seqiv_alloc(struct rtattr **tb)
+{
+ struct crypto_instance *inst;
+
+ inst = skcipher_geniv_alloc(&seqiv_tmpl, tb, 0, 0);
+ if (IS_ERR(inst))
+ goto out;
+
+ inst->alg.cra_ablkcipher.givencrypt = seqiv_givencrypt_first;
+
+ inst->alg.cra_init = seqiv_init;
+ inst->alg.cra_exit = skcipher_geniv_exit;
+
+ inst->alg.cra_alignmask |= __alignof__(u32) - 1;
+
+ inst->alg.cra_ctxsize = sizeof(struct seqiv_ctx);
+ inst->alg.cra_ctxsize += inst->alg.cra_ablkcipher.ivsize;
+
+out:
+ return inst;
+}
+
+static struct crypto_template seqiv_tmpl = {
+ .name = "seqiv",
+ .alloc = seqiv_alloc,
+ .free = skcipher_geniv_free,
+ .module = THIS_MODULE,
+};
+
+static int __init seqiv_module_init(void)
+{
+ return crypto_register_template(&seqiv_tmpl);
+}
+
+static void __exit seqiv_module_exit(void)
+{
+ crypto_unregister_template(&seqiv_tmpl);
+}
+
+module_init(seqiv_module_init);
+module_exit(seqiv_module_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Sequence Number IV Generator");