BACKPORT, FROMGIT: crypto: chacha20-generic - refactor to allow varying number of rounds

In preparation for adding XChaCha12 support, rename/refactor
chacha20-generic to support different numbers of rounds.  The
justification for needing XChaCha12 support is explained in more detail
in the patch "crypto: chacha - add XChaCha12 support".

The only difference between ChaCha{8,12,20} are the number of rounds
itself; all other parts of the algorithm are the same.  Therefore,
remove the "20" from all definitions, structures, functions, files, etc.
that will be shared by all ChaCha versions.

Also make ->setkey() store the round count in the chacha_ctx (previously
chacha20_ctx).  The generic code then passes the round count through to
chacha_block().  There will be a ->setkey() function for each explicitly
allowed round count; the encrypt/decrypt functions will be the same.  I
decided not to do it the opposite way (same ->setkey() function for all
round counts, with different encrypt/decrypt functions) because that
would have required more boilerplate code in architecture-specific
implementations of ChaCha and XChaCha.

Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: Martin Willi <martin@strongswan.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

(cherry picked from commit 1ca1b917940c24ca3d1f490118c5474168622953
 https://git.kernel.org/pub/scm/linux/kernel/git/herbert/cryptodev-2.6.git master)

Conflicts:
	arch/arm/crypto/chacha20-neon-glue.c
	arch/arm64/crypto/chacha20-neon-glue.c
	arch/x86/crypto/chacha20_glue.c
	drivers/char/random.c
	drivers/crypto/caam/caamalg.c
	drivers/crypto/caam/caamalg_qi2.c
	drivers/crypto/caam/compat.h
	include/crypto/chacha20.h
	lib/Makefile

Bug: 112008522
Test: As series, see Ic61c13b53facfd2173065be715a7ee5f3af8760b
Change-Id: I7fa203ddc7095ce8675a32f49b8a5230cd0cf5f6
Signed-off-by: Eric Biggers <ebiggers@google.com>
diff --git a/crypto/chacha20poly1305.c b/crypto/chacha20poly1305.c
index cb1c3a3..c0f699c 100644
--- a/crypto/chacha20poly1305.c
+++ b/crypto/chacha20poly1305.c
@@ -13,7 +13,7 @@
 #include <crypto/internal/hash.h>
 #include <crypto/internal/skcipher.h>
 #include <crypto/scatterwalk.h>
-#include <crypto/chacha20.h>
+#include <crypto/chacha.h>
 #include <crypto/poly1305.h>
 #include <linux/err.h>
 #include <linux/init.h>
@@ -51,7 +51,7 @@
 };
 
 struct chacha_req {
-	u8 iv[CHACHA20_IV_SIZE];
+	u8 iv[CHACHA_IV_SIZE];
 	struct scatterlist src[1];
 	struct skcipher_request req; /* must be last member */
 };
@@ -91,7 +91,7 @@
 	memcpy(iv, &leicb, sizeof(leicb));
 	memcpy(iv + sizeof(leicb), ctx->salt, ctx->saltlen);
 	memcpy(iv + sizeof(leicb) + ctx->saltlen, req->iv,
-	       CHACHA20_IV_SIZE - sizeof(leicb) - ctx->saltlen);
+	       CHACHA_IV_SIZE - sizeof(leicb) - ctx->saltlen);
 }
 
 static int poly_verify_tag(struct aead_request *req)
@@ -494,7 +494,7 @@
 	struct chachapoly_ctx *ctx = crypto_aead_ctx(aead);
 	int err;
 
-	if (keylen != ctx->saltlen + CHACHA20_KEY_SIZE)
+	if (keylen != ctx->saltlen + CHACHA_KEY_SIZE)
 		return -EINVAL;
 
 	keylen -= ctx->saltlen;
@@ -639,7 +639,7 @@
 
 	err = -EINVAL;
 	/* Need 16-byte IV size, including Initial Block Counter value */
-	if (crypto_skcipher_alg_ivsize(chacha) != CHACHA20_IV_SIZE)
+	if (crypto_skcipher_alg_ivsize(chacha) != CHACHA_IV_SIZE)
 		goto out_drop_chacha;
 	/* Not a stream cipher? */
 	if (chacha->base.cra_blocksize != 1)