[v3 PATCH 1/16] crypto: skcipher - Add skcipher walk interface

Herbert Xu
2016-11-22T12:08:25Z

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 | 511 +++++++++++++++++++++++++++++++++++++
include/crypto/internal/skcipher.h | 47 +++
2 files changed, 558 insertions(+)

diff --git a/crypto/skcipher.c b/crypto/skcipher.c
index f7d0018..0f30719 100644
--- a/crypto/skcipher.c
+++ b/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)
diff --git a/include/crypto/internal/skcipher.h b/include/crypto/internal/skcipher.h
index 7a7e815..d55041f 100644
--- a/include/crypto/internal/skcipher.h
+++ b/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 @@ static inline void crypto_skcipher_set_reqsize(
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)
{