crypto: chacha - constify ctx and iv arguments

Constify the ctx and iv arguments to crypto_chacha_init() and the
various chacha*_stream_xor() functions.  This makes it clear that they
are not modified.
Signed-off-by: NEric Biggers <ebiggers@google.com>
Acked-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

arch/arm/crypto/chacha-neon-glue.c

@@ -63,7 +63,7 @@ static void chacha_doneon(u32 *state, u8 *dst, const u8 *src,
 }
 
 static int chacha_neon_stream_xor(struct skcipher_request *req,
-				  struct chacha_ctx *ctx, u8 *iv)
+				  const struct chacha_ctx *ctx, const u8 *iv)
 {
 	struct skcipher_walk walk;
 	u32 state[16];

arch/arm64/crypto/chacha-neon-glue.c

@@ -60,7 +60,7 @@ static void chacha_doneon(u32 *state, u8 *dst, const u8 *src,
 }
 
 static int chacha_neon_stream_xor(struct skcipher_request *req,
-				  struct chacha_ctx *ctx, u8 *iv)
+				  const struct chacha_ctx *ctx, const u8 *iv)
 {
 	struct skcipher_walk walk;
 	u32 state[16];

arch/x86/crypto/chacha_glue.c

@@ -128,7 +128,7 @@ static void chacha_dosimd(u32 *state, u8 *dst, const u8 *src,
 }
 
 static int chacha_simd_stream_xor(struct skcipher_walk *walk,
-				  struct chacha_ctx *ctx, u8 *iv)
+				  const struct chacha_ctx *ctx, const u8 *iv)
 {
 	u32 *state, state_buf[16 + 2] __aligned(8);
 	int next_yield = 4096; /* bytes until next FPU yield */

crypto/chacha_generic.c

@@ -36,7 +36,7 @@ static void chacha_docrypt(u32 *state, u8 *dst, const u8 *src,
 }
 
 static int chacha_stream_xor(struct skcipher_request *req,
-			     struct chacha_ctx *ctx, u8 *iv)
+			     const struct chacha_ctx *ctx, const u8 *iv)
 {
 	struct skcipher_walk walk;
 	u32 state[16];
@@ -60,7 +60,7 @@ static int chacha_stream_xor(struct skcipher_request *req,
 	return err;
 }
 
-void crypto_chacha_init(u32 *state, struct chacha_ctx *ctx, u8 *iv)
+void crypto_chacha_init(u32 *state, const struct chacha_ctx *ctx, const u8 *iv)
 {
 	state[0]  = 0x61707865; /* "expa" */
 	state[1]  = 0x3320646e; /* "nd 3" */

include/crypto/chacha.h

@@ -41,7 +41,7 @@ static inline void chacha20_block(u32 *state, u8 *stream)
 }
 void hchacha_block(const u32 *in, u32 *out, int nrounds);
 
-void crypto_chacha_init(u32 *state, struct chacha_ctx *ctx, u8 *iv);
+void crypto_chacha_init(u32 *state, const struct chacha_ctx *ctx, const u8 *iv);
 
 int crypto_chacha20_setkey(struct crypto_skcipher *tfm, const u8 *key,
 			   unsigned int keysize);