[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 (file)
--- a/crypto/Kconfig
+++ b/crypto/Kconfig
@@ -32,6 +32,14 @@ config CRYPTO_BLKCIPHER
        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_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 968b796..1b99b3a 100644 (file)
--- 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 1052b31..2d7425f 100644 (file)
--- a/crypto/ctr.c
+++ b/crypto/ctr.c
@@ -361,6 +361,8 @@ static struct crypto_instance *crypto_rfc3686_alloc(struct rtattr **tb)
        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 (file)
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");