[CRYPTO] cipher: Added block cipher type

This patch adds the new type of block ciphers.  Unlike current cipher
algorithms which operate on a single block at a time, block ciphers
operate on an arbitrarily long linear area of data.  As it is block-based,
it will skip any data remaining at the end which cannot form a block.

The block cipher has one major difference when compared to the existing
block cipher implementation.  The sg walking is now performed by the
algorithm rather than the cipher mid-layer.  This is needed for drivers
that directly support sg lists.  It also improves performance for all
algorithms as it reduces the total number of indirect calls by one.

In future the existing cipher algorithm will be converted to only have
a single-block interface.  This will be done after all existing users
have switched over to the new block cipher type.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 405 insertions, 0 deletions

diff --git a/crypto/blkcipher.c b/crypto/blkcipher.c
new file mode 100644
index 0000000..034c939b
--- /dev/null
+++ b/crypto/blkcipher.c
@@ -0,0 +1,405 @@
+/*
+ * Block chaining cipher operations.
+ * 
+ * Generic encrypt/decrypt wrapper for ciphers, handles operations across
+ * multiple page boundaries by using temporary blocks.  In user context,
+ * the kernel is given a chance to schedule us once per page.
+ *
+ * Copyright (c) 2006 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 <linux/crypto.h>
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/scatterlist.h>
+#include <linux/seq_file.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+
+#include "internal.h"
+#include "scatterwalk.h"
+
+enum {
+	BLKCIPHER_WALK_PHYS = 1 << 0,
+	BLKCIPHER_WALK_SLOW = 1 << 1,
+	BLKCIPHER_WALK_COPY = 1 << 2,
+	BLKCIPHER_WALK_DIFF = 1 << 3,
+};
+
+static int blkcipher_walk_next(struct blkcipher_desc *desc,
+			       struct blkcipher_walk *walk);
+static int blkcipher_walk_first(struct blkcipher_desc *desc,
+				struct blkcipher_walk *walk);
+
+static inline void blkcipher_map_src(struct blkcipher_walk *walk)
+{
+	walk->src.virt.addr = scatterwalk_map(&walk->in, 0);
+}
+
+static inline void blkcipher_map_dst(struct blkcipher_walk *walk)
+{
+	walk->dst.virt.addr = scatterwalk_map(&walk->out, 1);
+}
+
+static inline void blkcipher_unmap_src(struct blkcipher_walk *walk)
+{
+	scatterwalk_unmap(walk->src.virt.addr, 0);
+}
+
+static inline void blkcipher_unmap_dst(struct blkcipher_walk *walk)
+{
+	scatterwalk_unmap(walk->dst.virt.addr, 1);
+}
+
+static inline u8 *blkcipher_get_spot(u8 *start, unsigned int len)
+{
+	if (offset_in_page(start + len) < len)
+		return (u8 *)((unsigned long)(start + len) & PAGE_MASK);
+	return start;
+}
+
+static inline unsigned int blkcipher_done_slow(struct crypto_blkcipher *tfm,
+					       struct blkcipher_walk *walk,
+					       unsigned int bsize)
+{
+	u8 *addr;
+	unsigned int alignmask = crypto_blkcipher_alignmask(tfm);
+
+	addr = (u8 *)ALIGN((unsigned long)walk->buffer, alignmask + 1);
+	addr = blkcipher_get_spot(addr, bsize);
+	scatterwalk_copychunks(addr, &walk->out, bsize, 1);
+	return bsize;
+}
+
+static inline unsigned int blkcipher_done_fast(struct blkcipher_walk *walk,
+					       unsigned int n)
+{
+	n = walk->nbytes - n;
+
+	if (walk->flags & BLKCIPHER_WALK_COPY) {
+		blkcipher_map_dst(walk);
+		memcpy(walk->dst.virt.addr, walk->page, n);
+		blkcipher_unmap_dst(walk);
+	} else if (!(walk->flags & BLKCIPHER_WALK_PHYS)) {
+		blkcipher_unmap_src(walk);
+		if (walk->flags & BLKCIPHER_WALK_DIFF)
+			blkcipher_unmap_dst(walk);
+	}
+
+	scatterwalk_advance(&walk->in, n);
+	scatterwalk_advance(&walk->out, n);
+
+	return n;
+}
+
+int blkcipher_walk_done(struct blkcipher_desc *desc,
+			struct blkcipher_walk *walk, int err)
+{
+	struct crypto_blkcipher *tfm = desc->tfm;
+	unsigned int nbytes = 0;
+
+	if (likely(err >= 0)) {
+		unsigned int bsize = crypto_blkcipher_blocksize(tfm);
+		unsigned int n;
+
+		if (likely(!(walk->flags & BLKCIPHER_WALK_SLOW)))
+			n = blkcipher_done_fast(walk, err);
+		else
+			n = blkcipher_done_slow(tfm, walk, bsize);
+
+		nbytes = walk->total - n;
+		err = 0;
+	}
+
+	scatterwalk_done(&walk->in, 0, nbytes);
+	scatterwalk_done(&walk->out, 1, nbytes);
+
+	walk->total = nbytes;
+	walk->nbytes = nbytes;
+
+	if (nbytes) {
+		crypto_yield(desc->flags);
+		return blkcipher_walk_next(desc, walk);
+	}
+
+	if (walk->iv != desc->info)
+		memcpy(desc->info, walk->iv, crypto_blkcipher_ivsize(tfm));
+	if (walk->buffer != walk->page)
+		kfree(walk->buffer);
+	if (walk->page)
+		free_page((unsigned long)walk->page);
+
+	return err;
+}
+EXPORT_SYMBOL_GPL(blkcipher_walk_done);
+
+static inline int blkcipher_next_slow(struct blkcipher_desc *desc,
+				      struct blkcipher_walk *walk,
+				      unsigned int bsize,
+				      unsigned int alignmask)
+{
+	unsigned int n;
+
+	if (walk->buffer)
+		goto ok;
+
+	walk->buffer = walk->page;
+	if (walk->buffer)
+		goto ok;
+
+	n = bsize * 2 + (alignmask & ~(crypto_tfm_ctx_alignment() - 1));
+	walk->buffer = kmalloc(n, GFP_ATOMIC);
+	if (!walk->buffer)
+		return blkcipher_walk_done(desc, walk, -ENOMEM);
+
+ok:
+	walk->dst.virt.addr = (u8 *)ALIGN((unsigned long)walk->buffer,
+					  alignmask + 1);
+	walk->dst.virt.addr = blkcipher_get_spot(walk->dst.virt.addr, bsize);
+	walk->src.virt.addr = blkcipher_get_spot(walk->dst.virt.addr + bsize,
+						 bsize);
+
+	scatterwalk_copychunks(walk->src.virt.addr, &walk->in, bsize, 0);
+
+	walk->nbytes = bsize;
+	walk->flags |= BLKCIPHER_WALK_SLOW;
+
+	return 0;
+}
+
+static inline int blkcipher_next_copy(struct blkcipher_walk *walk)
+{
+	u8 *tmp = walk->page;
+
+	blkcipher_map_src(walk);
+	memcpy(tmp, walk->src.virt.addr, walk->nbytes);
+	blkcipher_unmap_src(walk);
+
+	walk->src.virt.addr = tmp;
+	walk->dst.virt.addr = tmp;
+
+	return 0;
+}
+
+static inline int blkcipher_next_fast(struct blkcipher_desc *desc,
+				      struct blkcipher_walk *walk)
+{
+	unsigned long diff;
+
+	walk->src.phys.page = scatterwalk_page(&walk->in);
+	walk->src.phys.offset = offset_in_page(walk->in.offset);
+	walk->dst.phys.page = scatterwalk_page(&walk->out);
+	walk->dst.phys.offset = offset_in_page(walk->out.offset);
+
+	if (walk->flags & BLKCIPHER_WALK_PHYS)
+		return 0;
+
+	diff = walk->src.phys.offset - walk->dst.phys.offset;
+	diff |= walk->src.virt.page - walk->dst.virt.page;
+
+	blkcipher_map_src(walk);
+	walk->dst.virt.addr = walk->src.virt.addr;
+
+	if (diff) {
+		walk->flags |= BLKCIPHER_WALK_DIFF;
+		blkcipher_map_dst(walk);
+	}
+
+	return 0;
+}
+
+static int blkcipher_walk_next(struct blkcipher_desc *desc,
+			       struct blkcipher_walk *walk)
+{
+	struct crypto_blkcipher *tfm = desc->tfm;
+	unsigned int alignmask = crypto_blkcipher_alignmask(tfm);
+	unsigned int bsize = crypto_blkcipher_blocksize(tfm);
+	unsigned int n;
+	int err;
+
+	n = walk->total;
+	if (unlikely(n < bsize)) {
+		desc->flags |= CRYPTO_TFM_RES_BAD_BLOCK_LEN;
+		return blkcipher_walk_done(desc, walk, -EINVAL);
+	}
+
+	walk->flags &= ~(BLKCIPHER_WALK_SLOW | BLKCIPHER_WALK_COPY |
+			 BLKCIPHER_WALK_DIFF);
+	if (!scatterwalk_aligned(&walk->in, alignmask) ||
+	    !scatterwalk_aligned(&walk->out, alignmask)) {
+		walk->flags |= BLKCIPHER_WALK_COPY;
+		if (!walk->page) {
+			walk->page = (void *)__get_free_page(GFP_ATOMIC);
+			if (!walk->page)
+				n = 0;
+		}
+	}
+
+	n = scatterwalk_clamp(&walk->in, n);
+	n = scatterwalk_clamp(&walk->out, n);
+
+	if (unlikely(n < bsize)) {
+		err = blkcipher_next_slow(desc, walk, bsize, alignmask);
+		goto set_phys_lowmem;
+	}
+
+	walk->nbytes = n;
+	if (walk->flags & BLKCIPHER_WALK_COPY) {
+		err = blkcipher_next_copy(walk);
+		goto set_phys_lowmem;
+	}
+
+	return blkcipher_next_fast(desc, walk);
+
+set_phys_lowmem:
+	if (walk->flags & BLKCIPHER_WALK_PHYS) {
+		walk->src.phys.page = virt_to_page(walk->src.virt.addr);
+		walk->dst.phys.page = virt_to_page(walk->dst.virt.addr);
+		walk->src.phys.offset &= PAGE_SIZE - 1;
+		walk->dst.phys.offset &= PAGE_SIZE - 1;
+	}
+	return err;
+}
+
+static inline int blkcipher_copy_iv(struct blkcipher_walk *walk,
+				    struct crypto_blkcipher *tfm,
+				    unsigned int alignmask)
+{
+	unsigned bs = crypto_blkcipher_blocksize(tfm);
+	unsigned int ivsize = crypto_blkcipher_ivsize(tfm);
+	unsigned int size = bs * 2 + ivsize + max(bs, ivsize) - (alignmask + 1);
+	u8 *iv;
+
+	size += alignmask & ~(crypto_tfm_ctx_alignment() - 1);
+	walk->buffer = kmalloc(size, GFP_ATOMIC);
+	if (!walk->buffer)
+		return -ENOMEM;
+
+	iv = (u8 *)ALIGN((unsigned long)walk->buffer, alignmask + 1);
+	iv = blkcipher_get_spot(iv, bs) + bs;
+	iv = blkcipher_get_spot(iv, bs) + bs;
+	iv = blkcipher_get_spot(iv, ivsize);
+
+	walk->iv = memcpy(iv, walk->iv, ivsize);
+	return 0;
+}
+
+int blkcipher_walk_virt(struct blkcipher_desc *desc,
+			struct blkcipher_walk *walk)
+{
+	walk->flags &= ~BLKCIPHER_WALK_PHYS;
+	return blkcipher_walk_first(desc, walk);
+}
+EXPORT_SYMBOL_GPL(blkcipher_walk_virt);
+
+int blkcipher_walk_phys(struct blkcipher_desc *desc,
+			struct blkcipher_walk *walk)
+{
+	walk->flags |= BLKCIPHER_WALK_PHYS;
+	return blkcipher_walk_first(desc, walk);
+}
+EXPORT_SYMBOL_GPL(blkcipher_walk_phys);
+
+static int blkcipher_walk_first(struct blkcipher_desc *desc,
+				struct blkcipher_walk *walk)
+{
+	struct crypto_blkcipher *tfm = desc->tfm;
+	unsigned int alignmask = crypto_blkcipher_alignmask(tfm);
+
+	walk->nbytes = walk->total;
+	if (unlikely(!walk->total))
+		return 0;
+
+	walk->buffer = NULL;
+	walk->iv = desc->info;
+	if (unlikely(((unsigned long)walk->iv & alignmask))) {
+		int err = blkcipher_copy_iv(walk, tfm, alignmask);
+		if (err)
+			return err;
+	}
+
+	scatterwalk_start(&walk->in, walk->in.sg);
+	scatterwalk_start(&walk->out, walk->out.sg);
+	walk->page = NULL;
+
+	return blkcipher_walk_next(desc, walk);
+}
+
+static int setkey(struct crypto_tfm *tfm, const u8 *key,
+		  unsigned int keylen)
+{
+	struct blkcipher_alg *cipher = &tfm->__crt_alg->cra_blkcipher;
+
+	if (keylen < cipher->min_keysize || keylen > cipher->max_keysize) {
+		tfm->crt_flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
+		return -EINVAL;
+	}
+
+	return cipher->setkey(tfm, key, keylen);
+}
+
+static unsigned int crypto_blkcipher_ctxsize(struct crypto_alg *alg)
+{
+	struct blkcipher_alg *cipher = &alg->cra_blkcipher;
+	unsigned int len = alg->cra_ctxsize;
+
+	if (cipher->ivsize) {
+		len = ALIGN(len, (unsigned long)alg->cra_alignmask + 1);
+		len += cipher->ivsize;
+	}
+
+	return len;
+}
+
+static int crypto_init_blkcipher_ops(struct crypto_tfm *tfm)
+{
+	struct blkcipher_tfm *crt = &tfm->crt_blkcipher;
+	struct blkcipher_alg *alg = &tfm->__crt_alg->cra_blkcipher;
+	unsigned long align = crypto_tfm_alg_alignmask(tfm) + 1;
+	unsigned long addr;
+
+	if (alg->ivsize > PAGE_SIZE / 8)
+		return -EINVAL;
+
+	crt->setkey = setkey;
+	crt->encrypt = alg->encrypt;
+	crt->decrypt = alg->decrypt;
+
+	addr = (unsigned long)crypto_tfm_ctx(tfm);
+	addr = ALIGN(addr, align);
+	addr += ALIGN(tfm->__crt_alg->cra_ctxsize, align);
+	crt->iv = (void *)addr;
+
+	return 0;
+}
+
+static void crypto_blkcipher_show(struct seq_file *m, struct crypto_alg *alg)
+	__attribute_used__;
+static void crypto_blkcipher_show(struct seq_file *m, struct crypto_alg *alg)
+{
+	seq_printf(m, "type         : blkcipher\n");
+	seq_printf(m, "blocksize    : %u\n", alg->cra_blocksize);
+	seq_printf(m, "min keysize  : %u\n", alg->cra_blkcipher.min_keysize);
+	seq_printf(m, "max keysize  : %u\n", alg->cra_blkcipher.max_keysize);
+	seq_printf(m, "ivsize       : %u\n", alg->cra_blkcipher.ivsize);
+}
+
+const struct crypto_type crypto_blkcipher_type = {
+	.ctxsize = crypto_blkcipher_ctxsize,
+	.init = crypto_init_blkcipher_ops,
+#ifdef CONFIG_PROC_FS
+	.show = crypto_blkcipher_show,
+#endif
+};
+EXPORT_SYMBOL_GPL(crypto_blkcipher_type);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Generic block chaining cipher type");