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authorArd Biesheuvel <ard.biesheuvel@linaro.org>2019-07-02 21:41:34 +0200
committerHerbert Xu <herbert@gondor.apana.org.au>2019-07-26 14:56:07 +1000
commitd9ec772d9550b6e513c51bc4e6fa1e3ffb50181c (patch)
tree3d9aaca48f445128982d7acfe13916ddf00c22c9 /include/crypto
parent5bb12d7825adf0e80b849a273834f3131a6cc4e1 (diff)
crypto: ctr - add helper for performing a CTR encryption walk
Add a static inline helper modeled after crypto_cbc_encrypt_walk() that can be reused for SIMD algorithms that need to implement a non-SIMD fallback for performing CTR encryption. Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Diffstat (limited to 'include/crypto')
-rw-r--r--include/crypto/ctr.h50
1 files changed, 50 insertions, 0 deletions
diff --git a/include/crypto/ctr.h b/include/crypto/ctr.h
index 06984a26c8cf..a1c66d1001af 100644
--- a/include/crypto/ctr.h
+++ b/include/crypto/ctr.h
@@ -8,8 +8,58 @@
#ifndef _CRYPTO_CTR_H
#define _CRYPTO_CTR_H
+#include <crypto/algapi.h>
+#include <crypto/internal/skcipher.h>
+#include <linux/string.h>
+#include <linux/types.h>
+
#define CTR_RFC3686_NONCE_SIZE 4
#define CTR_RFC3686_IV_SIZE 8
#define CTR_RFC3686_BLOCK_SIZE 16
+static inline int crypto_ctr_encrypt_walk(struct skcipher_request *req,
+ void (*fn)(struct crypto_skcipher *,
+ const u8 *, u8 *))
+{
+ struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
+ int blocksize = crypto_skcipher_chunksize(tfm);
+ u8 buf[MAX_CIPHER_BLOCKSIZE];
+ struct skcipher_walk walk;
+ int err;
+
+ /* avoid integer division due to variable blocksize parameter */
+ if (WARN_ON_ONCE(!is_power_of_2(blocksize)))
+ return -EINVAL;
+
+ err = skcipher_walk_virt(&walk, req, false);
+
+ while (walk.nbytes > 0) {
+ u8 *dst = walk.dst.virt.addr;
+ u8 *src = walk.src.virt.addr;
+ int nbytes = walk.nbytes;
+ int tail = 0;
+
+ if (nbytes < walk.total) {
+ tail = walk.nbytes & (blocksize - 1);
+ nbytes -= tail;
+ }
+
+ do {
+ int bsize = min(nbytes, blocksize);
+
+ fn(tfm, walk.iv, buf);
+
+ crypto_xor_cpy(dst, src, buf, bsize);
+ crypto_inc(walk.iv, blocksize);
+
+ dst += bsize;
+ src += bsize;
+ nbytes -= bsize;
+ } while (nbytes > 0);
+
+ err = skcipher_walk_done(&walk, tail);
+ }
+ return err;
+}
+
#endif /* _CRYPTO_CTR_H */