crypto: xts: add interface for parallelized cipher implementations

Add xts_crypt() function that can be used by cipher implementations that can
benefit from parallelized cipher operations.

Signed-off-by: Jussi Kivilinna <jussi.kivilinna@mbnet.fi>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

2 files changed, 100 insertions, 2 deletions

diff --git a/crypto/xts.c b/crypto/xts.c
index 96f3f88d576e..ca1608f44cb5 100644
--- a/crypto/xts.c
+++ b/crypto/xts.c
@@ -21,11 +21,10 @@
 #include <linux/scatterlist.h>
 #include <linux/slab.h>
 
+#include <crypto/xts.h>
 #include <crypto/b128ops.h>
 #include <crypto/gf128mul.h>
 
-#define XTS_BLOCK_SIZE 16
-
 struct priv {
         struct crypto_cipher *child;
         struct crypto_cipher *tweak;
@@ -167,6 +166,78 @@ static int decrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
                      crypto_cipher_alg(ctx->child)->cia_decrypt);
 }
 
+int xts_crypt(struct blkcipher_desc *desc, struct scatterlist *sdst,
+              struct scatterlist *ssrc, unsigned int nbytes,
+              struct xts_crypt_req *req)
+{
+        const unsigned int bsize = XTS_BLOCK_SIZE;
+        const unsigned int max_blks = req->tbuflen / bsize;
+        struct blkcipher_walk walk;
+        unsigned int nblocks;
+        be128 *src, *dst, *t;
+        be128 *t_buf = req->tbuf;
+        int err, i;
+
+        BUG_ON(max_blks < 1);
+
+        blkcipher_walk_init(&walk, sdst, ssrc, nbytes);
+
+        err = blkcipher_walk_virt(desc, &walk);
+        nbytes = walk.nbytes;
+        if (!nbytes)
+                return err;
+
+        nblocks = min(nbytes / bsize, max_blks);
+        src = (be128 *)walk.src.virt.addr;
+        dst = (be128 *)walk.dst.virt.addr;
+
+        /* calculate first value of T */
+        req->tweak_fn(req->tweak_ctx, (u8 *)&t_buf[0], walk.iv);
+
+        i = 0;
+        goto first;
+
+        for (;;) {
+                do {
+                        for (i = 0; i < nblocks; i++) {
+                                gf128mul_x_ble(&t_buf[i], t);
+first:
+                                t = &t_buf[i];
+
+                                /* PP <- T xor P */
+                                be128_xor(dst + i, t, src + i);
+                        }
+
+                        /* CC <- E(Key2,PP) */
+                        req->crypt_fn(req->crypt_ctx, (u8 *)dst,
+                                      nblocks * bsize);
+
+                        /* C <- T xor CC */
+                        for (i = 0; i < nblocks; i++)
+                                be128_xor(dst + i, dst + i, &t_buf[i]);
+
+                        src += nblocks;
+                        dst += nblocks;
+                        nbytes -= nblocks * bsize;
+                        nblocks = min(nbytes / bsize, max_blks);
+                } while (nblocks > 0);
+
+                *(be128 *)walk.iv = *t;
+
+                err = blkcipher_walk_done(desc, &walk, nbytes);
+                nbytes = walk.nbytes;
+                if (!nbytes)
+                        break;
+
+                nblocks = min(nbytes / bsize, max_blks);
+                src = (be128 *)walk.src.virt.addr;
+                dst = (be128 *)walk.dst.virt.addr;
+        }
+
+        return err;
+}
+EXPORT_SYMBOL_GPL(xts_crypt);
+
 static int init_tfm(struct crypto_tfm *tfm)
 {
         struct crypto_cipher *cipher;
diff --git a/include/crypto/xts.h b/include/crypto/xts.h
new file mode 100644
index 000000000000..72c09eb56437
--- /dev/null
+++ b/include/crypto/xts.h
@@ -0,0 +1,27 @@
+#ifndef _CRYPTO_XTS_H
+#define _CRYPTO_XTS_H
+
+#include <crypto/b128ops.h>
+
+struct scatterlist;
+struct blkcipher_desc;
+
+#define XTS_BLOCK_SIZE 16
+
+struct xts_crypt_req {
+        be128 *tbuf;
+        unsigned int tbuflen;
+
+        void *tweak_ctx;
+        void (*tweak_fn)(void *ctx, u8* dst, const u8* src);
+        void *crypt_ctx;
+        void (*crypt_fn)(void *ctx, u8 *blks, unsigned int nbytes);
+};
+
+#define XTS_TWEAK_CAST(x) ((void (*)(void *, u8*, const u8*))(x))
+
+int xts_crypt(struct blkcipher_desc *desc, struct scatterlist *dst,
+              struct scatterlist *src, unsigned int nbytes,
+              struct xts_crypt_req *req);
+
+#endif  /* _CRYPTO_XTS_H */