[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 <[email protected]>
---
crypto/Kconfig | 5 +
crypto/Makefile | 1
crypto/ctr.c | 2
crypto/seqiv.c | 202 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
4 files changed, 210 insertions(+)
diff --git a/crypto/Kconfig b/crypto/Kconfig
index 0528702..d2e1ae6 100644
--- a/crypto/Kconfig
+++ b/crypto/Kconfig
@@ -32,6 +32,10 @@ config CRYPTO_BLKCIPHER
tristate
select CRYPTO_ALGAPI
+config CRYPTO_SEQIV
+ tristate
+ select CRYPTO_BLKCIPHER
+
config CRYPTO_HASH
tristate
select CRYPTO_ALGAPI
@@ -197,6 +201,7 @@ config CRYPTO_XTS
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 4d50435..2770ad8 100644
--- a/crypto/Makefile
+++ b/crypto/Makefile
@@ -15,6 +15,7 @@ crypto_blkcipher-objs += blkcipher.o
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 b816e95..47e044a 100644
--- a/crypto/ctr.c
+++ b/crypto/ctr.c
@@ -286,6 +286,8 @@ static struct crypto_instance *crypto_ctr_alloc(struct rtattr **tb)
inst->alg.cra_blkcipher.max_keysize = alg->cra_cipher.cia_max_keysize
+ noncesize;
+ memcpy(inst->alg.cra_blkcipher.geniv, "seqiv", sizeof("seqiv"));
+
inst->alg.cra_ctxsize = sizeof(struct crypto_ctr_ctx);
inst->alg.cra_init = crypto_ctr_init_tfm;
diff --git a/crypto/seqiv.c b/crypto/seqiv.c
new file mode 100644
index 0000000..77277d2
--- /dev/null
+++ b/crypto/seqiv.c
@@ -0,0 +1,202 @@
+/*
+ * 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 <[email protected]>
+ *
+ * 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/spinlock.h>
+#include <linux/string.h>
+
+struct seqiv_ctx {
+ struct crypto_ablkcipher *cipher;
+ spinlock_t lock;
+ u8 salt[] __attribute__ ((aligned(__alignof__(u32))));
+};
+
+static void seqiv_complete2(struct ablkcipher_request *req, int err)
+{
+ struct ablkcipher_request *subreq = ablkcipher_request_ctx(req);
+ struct crypto_ablkcipher *geniv;
+
+ if (err == -EINPROGRESS)
+ return;
+
+ if (err)
+ goto out;
+
+ geniv = crypto_ablkcipher_reqtfm(req);
+ memcpy(req->info, subreq->info, crypto_ablkcipher_ivsize(geniv));
+
+out:
+ kfree(subreq->info);
+}
+
+static void seqiv_complete(struct crypto_async_request *base, int err)
+{
+ struct ablkcipher_request *req = base->data;
+
+ seqiv_complete2(req, err);
+ ablkcipher_request_complete(req, err);
+}
+
+static int seqiv_givcrypt(struct ablkcipher_request *req)
+{
+ struct crypto_ablkcipher *geniv = crypto_ablkcipher_reqtfm(req);
+ struct seqiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
+ struct ablkcipher_request *subreq = ablkcipher_request_ctx(req);
+ crypto_completion_t complete;
+ void *data;
+ u8 *info;
+ __be64 seq;
+ unsigned int ivsize;
+ unsigned int len;
+ int err;
+
+ ablkcipher_request_set_tfm(subreq, ctx->cipher);
+
+ complete = req->base.complete;
+ data = req->base.data;
+ info = req->info;
+
+ ivsize = crypto_ablkcipher_ivsize(geniv);
+
+ if (!IS_ALIGNED((unsigned long)info,
+ crypto_ablkcipher_alignmask(geniv) + 1)) {
+ info = kmalloc(ivsize, req->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->base.flags, complete,
+ data);
+ ablkcipher_request_set_crypt(subreq, req->src, req->dst, req->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 (info != req->info)
+ seqiv_complete2(req, err);
+ return err;
+}
+
+static int seqiv_givcrypt_first(struct ablkcipher_request *req)
+{
+ struct crypto_ablkcipher *geniv = crypto_ablkcipher_reqtfm(req);
+ struct seqiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
+ struct crypto_ablkcipher *cipher = ctx->cipher;
+
+ spin_lock_bh(&ctx->lock);
+ if (crypto_ablkcipher_crt(cipher)->givcrypt != seqiv_givcrypt_first)
+ goto unlock;
+
+ crypto_ablkcipher_crt(cipher)->givcrypt = seqiv_givcrypt;
+ get_random_bytes(ctx->salt, crypto_ablkcipher_ivsize(geniv));
+
+unlock:
+ spin_unlock_bh(&ctx->lock);
+
+ return seqiv_givcrypt(req);
+}
+
+static int seqiv_init(struct crypto_tfm *tfm)
+{
+ struct crypto_instance *inst = (void *)tfm->__crt_alg;
+ struct crypto_spawn *spawn = crypto_instance_ctx(inst);
+ struct seqiv_ctx *ctx = crypto_tfm_ctx(tfm);
+ struct crypto_ablkcipher *cipher;
+
+ cipher = crypto_spawn_nivcipher(spawn);
+ if (IS_ERR(cipher))
+ return PTR_ERR(cipher);
+
+ ctx->cipher = cipher;
+ spin_lock_init(&ctx->lock);
+
+ tfm->crt_ablkcipher.reqsize = sizeof(struct ablkcipher_request) +
+ crypto_ablkcipher_reqsize(cipher);
+
+ return 0;
+}
+
+static void seqiv_exit(struct crypto_tfm *tfm)
+{
+ struct seqiv_ctx *ctx = crypto_tfm_ctx(tfm);
+ crypto_free_ablkcipher(ctx->cipher);
+}
+
+static struct crypto_template crypto_seqiv_tmpl;
+
+static struct crypto_instance *seqiv_alloc(struct rtattr **tb)
+{
+ struct crypto_instance *inst;
+
+ inst = givcipher_alloc_inst(&crypto_seqiv_tmpl, tb, 0, 0);
+ if (IS_ERR(inst))
+ goto out;
+
+ inst->alg.cra_ablkcipher.givcrypt = seqiv_givcrypt_first;
+
+ inst->alg.cra_init = seqiv_init;
+ inst->alg.cra_exit = seqiv_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 = givcipher_free_inst,
+ .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");