crypto: skcipher - Add skcipher walk interface

This patch adds the skcipher walk interface which replaces both
blkcipher walk and ablkcipher walk.  Just like blkcipher walk it
can also be used for AEAD algorithms.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

crypto/skcipher.c

@@ -14,9 +14,12 @@
  *
  */
 
+#include <crypto/internal/aead.h>
 #include <crypto/internal/skcipher.h>
+#include <crypto/scatterwalk.h>
 #include <linux/bug.h>
 #include <linux/cryptouser.h>
+#include <linux/list.h>
 #include <linux/module.h>
 #include <linux/rtnetlink.h>
 #include <linux/seq_file.h>
@@ -24,6 +27,514 @@
 
 #include "internal.h"
 
+enum {
+	SKCIPHER_WALK_PHYS = 1 << 0,
+	SKCIPHER_WALK_SLOW = 1 << 1,
+	SKCIPHER_WALK_COPY = 1 << 2,
+	SKCIPHER_WALK_DIFF = 1 << 3,
+	SKCIPHER_WALK_SLEEP = 1 << 4,
+};
+
+struct skcipher_walk_buffer {
+	struct list_head entry;
+	struct scatter_walk dst;
+	unsigned int len;
+	u8 *data;
+	u8 buffer[];
+};
+
+static int skcipher_walk_next(struct skcipher_walk *walk);
+
+static inline void skcipher_unmap(struct scatter_walk *walk, void *vaddr)
+{
+	if (PageHighMem(scatterwalk_page(walk)))
+		kunmap_atomic(vaddr);
+}
+
+static inline void *skcipher_map(struct scatter_walk *walk)
+{
+	struct page *page = scatterwalk_page(walk);
+
+	return (PageHighMem(page) ? kmap_atomic(page) : page_address(page)) +
+	       offset_in_page(walk->offset);
+}
+
+static inline void skcipher_map_src(struct skcipher_walk *walk)
+{
+	walk->src.virt.addr = skcipher_map(&walk->in);
+}
+
+static inline void skcipher_map_dst(struct skcipher_walk *walk)
+{
+	walk->dst.virt.addr = skcipher_map(&walk->out);
+}
+
+static inline void skcipher_unmap_src(struct skcipher_walk *walk)
+{
+	skcipher_unmap(&walk->in, walk->src.virt.addr);
+}
+
+static inline void skcipher_unmap_dst(struct skcipher_walk *walk)
+{
+	skcipher_unmap(&walk->out, walk->dst.virt.addr);
+}
+
+static inline gfp_t skcipher_walk_gfp(struct skcipher_walk *walk)
+{
+	return walk->flags & SKCIPHER_WALK_SLEEP ? GFP_KERNEL : GFP_ATOMIC;
+}
+
+/* Get a spot of the specified length that does not straddle a page.
+ * The caller needs to ensure that there is enough space for this operation.
+ */
+static inline u8 *skcipher_get_spot(u8 *start, unsigned int len)
+{
+	u8 *end_page = (u8 *)(((unsigned long)(start + len - 1)) & PAGE_MASK);
+
+	return max(start, end_page);
+}
+
+static int skcipher_done_slow(struct skcipher_walk *walk, unsigned int bsize)
+{
+	u8 *addr;
+
+	addr = (u8 *)ALIGN((unsigned long)walk->buffer, walk->alignmask + 1);
+	addr = skcipher_get_spot(addr, bsize);
+	scatterwalk_copychunks(addr, &walk->out, bsize,
+			       (walk->flags & SKCIPHER_WALK_PHYS) ? 2 : 1);
+	return 0;
+}
+
+int skcipher_walk_done(struct skcipher_walk *walk, int err)
+{
+	unsigned int n = walk->nbytes - err;
+	unsigned int nbytes;
+
+	nbytes = walk->total - n;
+
+	if (unlikely(err < 0)) {
+		nbytes = 0;
+		n = 0;
+	} else if (likely(!(walk->flags & (SKCIPHER_WALK_PHYS |
+					   SKCIPHER_WALK_SLOW |
+					   SKCIPHER_WALK_COPY |
+					   SKCIPHER_WALK_DIFF)))) {
+unmap_src:
+		skcipher_unmap_src(walk);
+	} else if (walk->flags & SKCIPHER_WALK_DIFF) {
+		skcipher_unmap_dst(walk);
+		goto unmap_src;
+	} else if (walk->flags & SKCIPHER_WALK_COPY) {
+		skcipher_map_dst(walk);
+		memcpy(walk->dst.virt.addr, walk->page, n);
+		skcipher_unmap_dst(walk);
+	} else if (unlikely(walk->flags & SKCIPHER_WALK_SLOW)) {
+		if (WARN_ON(err)) {
+			err = -EINVAL;
+			nbytes = 0;
+		} else
+			n = skcipher_done_slow(walk, n);
+	}
+
+	if (err > 0)
+		err = 0;
+
+	walk->total = nbytes;
+	walk->nbytes = nbytes;
+
+	scatterwalk_advance(&walk->in, n);
+	scatterwalk_advance(&walk->out, n);
+	scatterwalk_done(&walk->in, 0, nbytes);
+	scatterwalk_done(&walk->out, 1, nbytes);
+
+	if (nbytes) {
+		crypto_yield(walk->flags & SKCIPHER_WALK_SLEEP ?
+			     CRYPTO_TFM_REQ_MAY_SLEEP : 0);
+		return skcipher_walk_next(walk);
+	}
+
+	/* Short-circuit for the common/fast path. */
+	if (!((unsigned long)walk->buffer | (unsigned long)walk->page))
+		goto out;
+
+	if (walk->flags & SKCIPHER_WALK_PHYS)
+		goto out;
+
+	if (walk->iv != walk->oiv)
+		memcpy(walk->oiv, walk->iv, walk->ivsize);
+	if (walk->buffer != walk->page)
+		kfree(walk->buffer);
+	if (walk->page)
+		free_page((unsigned long)walk->page);
+
+out:
+	return err;
+}
+EXPORT_SYMBOL_GPL(skcipher_walk_done);
+
+void skcipher_walk_complete(struct skcipher_walk *walk, int err)
+{
+	struct skcipher_walk_buffer *p, *tmp;
+
+	list_for_each_entry_safe(p, tmp, &walk->buffers, entry) {
+		u8 *data;
+
+		if (err)
+			goto done;
+
+		data = p->data;
+		if (!data) {
+			data = PTR_ALIGN(&p->buffer[0], walk->alignmask + 1);
+			data = skcipher_get_spot(data, walk->chunksize);
+		}
+
+		scatterwalk_copychunks(data, &p->dst, p->len, 1);
+
+		if (offset_in_page(p->data) + p->len + walk->chunksize >
+		    PAGE_SIZE)
+			free_page((unsigned long)p->data);
+
+done:
+		list_del(&p->entry);
+		kfree(p);
+	}
+
+	if (!err && walk->iv != walk->oiv)
+		memcpy(walk->oiv, walk->iv, walk->ivsize);
+	if (walk->buffer != walk->page)
+		kfree(walk->buffer);
+	if (walk->page)
+		free_page((unsigned long)walk->page);
+}
+EXPORT_SYMBOL_GPL(skcipher_walk_complete);
+
+static void skcipher_queue_write(struct skcipher_walk *walk,
+				 struct skcipher_walk_buffer *p)
+{
+	p->dst = walk->out;
+	list_add_tail(&p->entry, &walk->buffers);
+}
+
+static int skcipher_next_slow(struct skcipher_walk *walk, unsigned int bsize)
+{
+	bool phys = walk->flags & SKCIPHER_WALK_PHYS;
+	unsigned alignmask = walk->alignmask;
+	struct skcipher_walk_buffer *p;
+	unsigned a;
+	unsigned n;
+	u8 *buffer;
+	void *v;
+
+	if (!phys) {
+		buffer = walk->buffer ?: walk->page;
+		if (buffer)
+			goto ok;
+	}
+
+	/* Start with the minimum alignment of kmalloc. */
+	a = crypto_tfm_ctx_alignment() - 1;
+	n = bsize;
+
+	if (phys) {
+		/* Calculate the minimum alignment of p->buffer. */
+		a &= (sizeof(*p) ^ (sizeof(*p) - 1)) >> 1;
+		n += sizeof(*p);
+	}
+
+	/* Minimum size to align p->buffer by alignmask. */
+	n += alignmask & ~a;
+
+	/* Minimum size to ensure p->buffer does not straddle a page. */
+	n += (bsize - 1) & ~(alignmask | a);
+
+	v = kzalloc(n, skcipher_walk_gfp(walk));
+	if (!v)
+		return skcipher_walk_done(walk, -ENOMEM);
+
+	if (phys) {
+		p = v;
+		p->len = bsize;
+		skcipher_queue_write(walk, p);
+		buffer = p->buffer;
+	} else {
+		walk->buffer = v;
+		buffer = v;
+	}
+
+ok:
+	walk->dst.virt.addr = PTR_ALIGN(buffer, alignmask + 1);
+	walk->dst.virt.addr = skcipher_get_spot(walk->dst.virt.addr, bsize);
+	walk->src.virt.addr = walk->dst.virt.addr;
+
+	scatterwalk_copychunks(walk->src.virt.addr, &walk->in, bsize, 0);
+
+	walk->nbytes = bsize;
+	walk->flags |= SKCIPHER_WALK_SLOW;
+
+	return 0;
+}
+
+static int skcipher_next_copy(struct skcipher_walk *walk)
+{
+	struct skcipher_walk_buffer *p;
+	u8 *tmp = walk->page;
+
+	skcipher_map_src(walk);
+	memcpy(tmp, walk->src.virt.addr, walk->nbytes);
+	skcipher_unmap_src(walk);
+
+	walk->src.virt.addr = tmp;
+	walk->dst.virt.addr = tmp;
+
+	if (!(walk->flags & SKCIPHER_WALK_PHYS))
+		return 0;
+
+	p = kmalloc(sizeof(*p), skcipher_walk_gfp(walk));
+	if (!p)
+		return -ENOMEM;
+
+	p->data = walk->page;
+	p->len = walk->nbytes;
+	skcipher_queue_write(walk, p);
+
+	if (offset_in_page(walk->page) + walk->nbytes + walk->chunksize >
+	    PAGE_SIZE)
+		walk->page = NULL;
+	else
+		walk->page += walk->nbytes;
+
+	return 0;
+}
+
+static int skcipher_next_fast(struct skcipher_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 & SKCIPHER_WALK_PHYS)
+		return 0;
+
+	diff = walk->src.phys.offset - walk->dst.phys.offset;
+	diff |= walk->src.virt.page - walk->dst.virt.page;
+
+	skcipher_map_src(walk);
+	walk->dst.virt.addr = walk->src.virt.addr;
+
+	if (diff) {
+		walk->flags |= SKCIPHER_WALK_DIFF;
+		skcipher_map_dst(walk);
+	}
+
+	return 0;
+}
+
+static int skcipher_walk_next(struct skcipher_walk *walk)
+{
+	unsigned int bsize;
+	unsigned int n;
+	int err;
+
+	walk->flags &= ~(SKCIPHER_WALK_SLOW | SKCIPHER_WALK_COPY |
+			 SKCIPHER_WALK_DIFF);
+
+	n = walk->total;
+	bsize = min(walk->chunksize, max(n, walk->blocksize));
+	n = scatterwalk_clamp(&walk->in, n);
+	n = scatterwalk_clamp(&walk->out, n);
+
+	if (unlikely(n < bsize)) {
+		if (unlikely(walk->total < walk->blocksize))
+			return skcipher_walk_done(walk, -EINVAL);
+
+slow_path:
+		err = skcipher_next_slow(walk, bsize);
+		goto set_phys_lowmem;
+	}
+
+	if (unlikely((walk->in.offset | walk->out.offset) & walk->alignmask)) {
+		if (!walk->page) {
+			gfp_t gfp = skcipher_walk_gfp(walk);
+
+			walk->page = (void *)__get_free_page(gfp);
+			if (!walk->page)
+				goto slow_path;
+		}
+
+		walk->nbytes = min_t(unsigned, n,
+				     PAGE_SIZE - offset_in_page(walk->page));
+		walk->flags |= SKCIPHER_WALK_COPY;
+		err = skcipher_next_copy(walk);
+		goto set_phys_lowmem;
+	}
+
+	walk->nbytes = n;
+
+	return skcipher_next_fast(walk);
+
+set_phys_lowmem:
+	if (!err && (walk->flags & SKCIPHER_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;
+}
+EXPORT_SYMBOL_GPL(skcipher_walk_next);
+
+static int skcipher_copy_iv(struct skcipher_walk *walk)
+{
+	unsigned a = crypto_tfm_ctx_alignment() - 1;
+	unsigned alignmask = walk->alignmask;
+	unsigned ivsize = walk->ivsize;
+	unsigned bs = walk->chunksize;
+	unsigned aligned_bs;
+	unsigned size;
+	u8 *iv;
+
+	aligned_bs = ALIGN(bs, alignmask);
+
+	/* Minimum size to align buffer by alignmask. */
+	size = alignmask & ~a;
+
+	if (walk->flags & SKCIPHER_WALK_PHYS)
+		size += ivsize;
+	else {
+		size += aligned_bs + ivsize;
+
+		/* Minimum size to ensure buffer does not straddle a page. */
+		size += (bs - 1) & ~(alignmask | a);
+	}
+
+	walk->buffer = kmalloc(size, skcipher_walk_gfp(walk));
+	if (!walk->buffer)
+		return -ENOMEM;
+
+	iv = PTR_ALIGN(walk->buffer, alignmask + 1);
+	iv = skcipher_get_spot(iv, bs) + aligned_bs;
+
+	walk->iv = memcpy(iv, walk->iv, walk->ivsize);
+	return 0;
+}
+
+static int skcipher_walk_first(struct skcipher_walk *walk)
+{
+	walk->nbytes = 0;
+
+	if (WARN_ON_ONCE(in_irq()))
+		return -EDEADLK;
+
+	if (unlikely(!walk->total))
+		return 0;
+
+	walk->buffer = NULL;
+	if (unlikely(((unsigned long)walk->iv & walk->alignmask))) {
+		int err = skcipher_copy_iv(walk);
+		if (err)
+			return err;
+	}
+
+	walk->page = NULL;
+	walk->nbytes = walk->total;
+
+	return skcipher_walk_next(walk);
+}
+
+static int skcipher_walk_skcipher(struct skcipher_walk *walk,
+				  struct skcipher_request *req)
+{
+	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
+
+	scatterwalk_start(&walk->in, req->src);
+	scatterwalk_start(&walk->out, req->dst);
+
+	walk->total = req->cryptlen;
+	walk->iv = req->iv;
+	walk->oiv = req->iv;
+
+	walk->flags &= ~SKCIPHER_WALK_SLEEP;
+	walk->flags |= req->base.flags & CRYPTO_TFM_REQ_MAY_SLEEP ?
+		       SKCIPHER_WALK_SLEEP : 0;
+
+	walk->blocksize = crypto_skcipher_blocksize(tfm);
+	walk->chunksize = crypto_skcipher_chunksize(tfm);
+	walk->ivsize = crypto_skcipher_ivsize(tfm);
+	walk->alignmask = crypto_skcipher_alignmask(tfm);
+
+	return skcipher_walk_first(walk);
+}
+
+int skcipher_walk_virt(struct skcipher_walk *walk,
+		       struct skcipher_request *req, bool atomic)
+{
+	int err;
+
+	walk->flags &= ~SKCIPHER_WALK_PHYS;
+
+	err = skcipher_walk_skcipher(walk, req);
+
+	walk->flags &= atomic ? ~SKCIPHER_WALK_SLEEP : ~0;
+
+	return err;
+}
+EXPORT_SYMBOL_GPL(skcipher_walk_virt);
+
+void skcipher_walk_atomise(struct skcipher_walk *walk)
+{
+	walk->flags &= ~SKCIPHER_WALK_SLEEP;
+}
+EXPORT_SYMBOL_GPL(skcipher_walk_atomise);
+
+int skcipher_walk_async(struct skcipher_walk *walk,
+			struct skcipher_request *req)
+{
+	walk->flags |= SKCIPHER_WALK_PHYS;
+
+	INIT_LIST_HEAD(&walk->buffers);
+
+	return skcipher_walk_skcipher(walk, req);
+}
+EXPORT_SYMBOL_GPL(skcipher_walk_async);
+
+int skcipher_walk_aead(struct skcipher_walk *walk, struct aead_request *req,
+		       bool atomic)
+{
+	struct crypto_aead *tfm = crypto_aead_reqtfm(req);
+	int err;
+
+	scatterwalk_start(&walk->in, req->src);
+	scatterwalk_start(&walk->out, req->dst);
+
+	scatterwalk_copychunks(NULL, &walk->in, req->assoclen, 2);
+	scatterwalk_copychunks(NULL, &walk->out, req->assoclen, 2);
+
+	walk->total = req->cryptlen;
+	walk->iv = req->iv;
+	walk->oiv = req->iv;
+
+	if (req->base.flags & CRYPTO_TFM_REQ_MAY_SLEEP)
+		walk->flags |= SKCIPHER_WALK_SLEEP;
+	else
+		walk->flags &= ~SKCIPHER_WALK_SLEEP;
+
+	walk->blocksize = crypto_aead_blocksize(tfm);
+	walk->chunksize = crypto_aead_chunksize(tfm);
+	walk->ivsize = crypto_aead_ivsize(tfm);
+	walk->alignmask = crypto_aead_alignmask(tfm);
+
+	err = skcipher_walk_first(walk);
+
+	if (atomic)
+		walk->flags &= ~SKCIPHER_WALK_SLEEP;
+
+	return err;
+}
+EXPORT_SYMBOL_GPL(skcipher_walk_aead);
+
 static unsigned int crypto_skcipher_extsize(struct crypto_alg *alg)
 {
 	if (alg->cra_type == &crypto_blkcipher_type)

include/crypto/internal/skcipher.h

@@ -15,8 +15,10 @@
 
 #include <crypto/algapi.h>
 #include <crypto/skcipher.h>
+#include <linux/list.h>
 #include <linux/types.h>
 
+struct aead_request;
 struct rtattr;
 
 struct skcipher_instance {
@@ -34,6 +36,40 @@ struct crypto_skcipher_spawn {
 	struct crypto_spawn base;
 };
 
+struct skcipher_walk {
+	union {
+		struct {
+			struct page *page;
+			unsigned long offset;
+		} phys;
+
+		struct {
+			u8 *page;
+			void *addr;
+		} virt;
+	} src, dst;
+
+	struct scatter_walk in;
+	unsigned int nbytes;
+
+	struct scatter_walk out;
+	unsigned int total;
+
+	struct list_head buffers;
+
+	u8 *page;
+	u8 *buffer;
+	u8 *oiv;
+	void *iv;
+
+	unsigned int ivsize;
+
+	int flags;
+	unsigned int blocksize;
+	unsigned int chunksize;
+	unsigned int alignmask;
+};
+
 extern const struct crypto_type crypto_givcipher_type;
 
 static inline struct crypto_instance *skcipher_crypto_instance(
@@ -104,6 +140,17 @@ void crypto_unregister_skciphers(struct skcipher_alg *algs, int count);
 int skcipher_register_instance(struct crypto_template *tmpl,
 			       struct skcipher_instance *inst);
 
+int skcipher_walk_done(struct skcipher_walk *walk, int err);
+int skcipher_walk_virt(struct skcipher_walk *walk,
+		       struct skcipher_request *req,
+		       bool atomic);
+void skcipher_walk_atomise(struct skcipher_walk *walk);
+int skcipher_walk_async(struct skcipher_walk *walk,
+			struct skcipher_request *req);
+int skcipher_walk_aead(struct skcipher_walk *walk, struct aead_request *req,
+		       bool atomic);
+void skcipher_walk_complete(struct skcipher_walk *walk, int err);
+
 static inline void ablkcipher_request_complete(struct ablkcipher_request *req,
 					       int err)
 {