[v4,02/35] crypto: chacha - move existing library code into lib/crypto

Message ID 20191017190932.1947-3-ard.biesheuvel@linaro.org
State New
Headers show
Series
  • crypto: crypto API library interfaces for WireGuard
Related show

Commit Message

Ard Biesheuvel Oct. 17, 2019, 7:08 p.m.
Currently, our generic ChaCha implementation consists of a permute
function in lib/chacha.c that operates on the 64-byte ChaCha state
directly [and which is always included into the core kernel since it
is used by the /dev/random driver], and the crypto API plumbing to
expose it as a skcipher.

In order to support in-kernel users that need the ChaCha streamcipher
but have no need [or tolerance] for going through the abstractions of
the crypto API, let's expose the streamcipher bits via a library API
as well, in a way that permits the implementation to be superseded by
an architecture specific one if provided.

So move the streamcipher code into a separate module in lib/crypto,
and expose the init() and crypt() routines to users of the library.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>

---
 arch/arm/crypto/chacha-neon-glue.c   |  2 +-
 arch/arm64/crypto/chacha-neon-glue.c |  2 +-
 arch/x86/crypto/chacha_glue.c        |  2 +-
 crypto/Kconfig                       |  1 +
 crypto/chacha_generic.c              | 60 ++---------------
 include/crypto/chacha.h              | 71 +++++++++++++++-----
 include/crypto/internal/chacha.h     | 41 +++++++++++
 lib/Makefile                         |  3 +-
 lib/crypto/Kconfig                   | 26 +++++++
 lib/crypto/Makefile                  |  4 ++
 lib/{ => crypto}/chacha.c            | 20 +++---
 lib/crypto/libchacha.c               | 35 ++++++++++
 12 files changed, 181 insertions(+), 86 deletions(-)

-- 
2.20.1

Comments

Eric Biggers Oct. 23, 2019, 3:05 a.m. | #1
On Thu, Oct 17, 2019 at 09:08:59PM +0200, Ard Biesheuvel wrote:
> +static inline void chacha_crypt(u32 *state, u8 *dst, const u8 *src,

> +				unsigned int bytes, int nrounds)

> +{

> +	if (IS_ENABLED(CONFIG_CRYPTO_ARCH_HAVE_LIB_CHACHA))

> +		chacha_crypt_arch(state, dst, src, bytes, nrounds);

> +	else

> +		chacha_crypt_generic(state, dst, src, bytes, nrounds);

> +}


How about also providing chacha20_crypt() which calls chacha_crypt(..., 20)?
The 'nrounds' parameter is really for implementations, rather than users of the
library API.  Users don't really have any business specifying the number of
rounds as an int.

> +static inline int chacha_setkey(struct crypto_skcipher *tfm, const u8 *key,

> +				unsigned int keysize, int nrounds)

> +{

> +	struct chacha_ctx *ctx = crypto_skcipher_ctx(tfm);

> +	int i;

> +

> +	if (keysize != CHACHA_KEY_SIZE)

> +		return -EINVAL;

> +

> +	for (i = 0; i < ARRAY_SIZE(ctx->key); i++)

> +		ctx->key[i] = get_unaligned_le32(key + i * sizeof(u32));

> +

> +	ctx->nrounds = nrounds;

> +	return 0;

> +}


At the end of this patch series there are 5 drivers which wrap chacha_setkey()
with chacha20_setkey() and chacha12_setkey() -- all 5 pairs identical.  How
about providing those as inline functions here?

> +config CRYPTO_LIB_CHACHA

> +	tristate "ChaCha library interface"

> +	depends on CRYPTO_ARCH_HAVE_LIB_CHACHA || !CRYPTO_ARCH_HAVE_LIB_CHACHA

> +	select CRYPTO_LIB_CHACHA_GENERIC if CRYPTO_ARCH_HAVE_LIB_CHACHA=n

> +	help

> +	  Enable the ChaCha library interface. This interface may be fulfilled

> +	  by either the generic implementation or an arch-specific one, if one

> +	  is available and enabled.


Since this is a library for use within the kernel, and not a user-visible
feature, I don't think it should be explicitly selectable.  I.e. it should just
be "tristate", without the prompt string.

- Eric
Eric Biggers Oct. 23, 2019, 3:12 a.m. | #2
On Thu, Oct 17, 2019 at 09:08:59PM +0200, Ard Biesheuvel wrote:
> diff --git a/lib/crypto/libchacha.c b/lib/crypto/libchacha.c

> new file mode 100644

> index 000000000000..7b4b97811f71

> --- /dev/null

> +++ b/lib/crypto/libchacha.c

> @@ -0,0 +1,35 @@

> +// SPDX-License-Identifier: GPL-2.0-or-later

> +/*

> + * The "hash function" used as the core of the ChaCha stream cipher (RFC7539)

> + *

> + * Copyright (C) 2015 Martin Willi

> + */


This new file actually contains the ChaCha stream cipher, not the ChaCha core.
So this file comment is incorrect.

- Eric
Ard Biesheuvel Nov. 4, 2019, 9:06 a.m. | #3
On Wed, 23 Oct 2019 at 05:05, Eric Biggers <ebiggers@kernel.org> wrote:
>

> On Thu, Oct 17, 2019 at 09:08:59PM +0200, Ard Biesheuvel wrote:

> > +static inline void chacha_crypt(u32 *state, u8 *dst, const u8 *src,

> > +                             unsigned int bytes, int nrounds)

> > +{

> > +     if (IS_ENABLED(CONFIG_CRYPTO_ARCH_HAVE_LIB_CHACHA))

> > +             chacha_crypt_arch(state, dst, src, bytes, nrounds);

> > +     else

> > +             chacha_crypt_generic(state, dst, src, bytes, nrounds);

> > +}

>

> How about also providing chacha20_crypt() which calls chacha_crypt(..., 20)?

> The 'nrounds' parameter is really for implementations, rather than users of the

> library API.  Users don't really have any business specifying the number of

> rounds as an int.

>


OK

> > +static inline int chacha_setkey(struct crypto_skcipher *tfm, const u8 *key,

> > +                             unsigned int keysize, int nrounds)

> > +{

> > +     struct chacha_ctx *ctx = crypto_skcipher_ctx(tfm);

> > +     int i;

> > +

> > +     if (keysize != CHACHA_KEY_SIZE)

> > +             return -EINVAL;

> > +

> > +     for (i = 0; i < ARRAY_SIZE(ctx->key); i++)

> > +             ctx->key[i] = get_unaligned_le32(key + i * sizeof(u32));

> > +

> > +     ctx->nrounds = nrounds;

> > +     return 0;

> > +}

>

> At the end of this patch series there are 5 drivers which wrap chacha_setkey()

> with chacha20_setkey() and chacha12_setkey() -- all 5 pairs identical.  How

> about providing those as inline functions here?

>


The reason I avoided this is because they are only invoked via
indirect calls, but actually, there's nothing wrong with letting the
compiler instantiate it where needed, so I'll change this.

> > +config CRYPTO_LIB_CHACHA

> > +     tristate "ChaCha library interface"

> > +     depends on CRYPTO_ARCH_HAVE_LIB_CHACHA || !CRYPTO_ARCH_HAVE_LIB_CHACHA

> > +     select CRYPTO_LIB_CHACHA_GENERIC if CRYPTO_ARCH_HAVE_LIB_CHACHA=n

> > +     help

> > +       Enable the ChaCha library interface. This interface may be fulfilled

> > +       by either the generic implementation or an arch-specific one, if one

> > +       is available and enabled.

>

> Since this is a library for use within the kernel, and not a user-visible

> feature, I don't think it should be explicitly selectable.  I.e. it should just

> be "tristate", without the prompt string.

>


The issue here is that it is not implicitly selectable either due to
the dependencies. E.g, if you select the generic version as a builtin
and the accelerated version as a module, you could enable the
chachapoly library interface as a builtin but it won't use the
accelerated code at all. So either we declare here that both need to
be either builtin or modules, or we ignore that and allow people to
create suboptimal Kconfigs.

Patch

diff --git a/arch/arm/crypto/chacha-neon-glue.c b/arch/arm/crypto/chacha-neon-glue.c
index a8e9b534c8da..26576772f18b 100644
--- a/arch/arm/crypto/chacha-neon-glue.c
+++ b/arch/arm/crypto/chacha-neon-glue.c
@@ -20,7 +20,7 @@ 
  */
 
 #include <crypto/algapi.h>
-#include <crypto/chacha.h>
+#include <crypto/internal/chacha.h>
 #include <crypto/internal/simd.h>
 #include <crypto/internal/skcipher.h>
 #include <linux/kernel.h>
diff --git a/arch/arm64/crypto/chacha-neon-glue.c b/arch/arm64/crypto/chacha-neon-glue.c
index 1495d2b18518..d4cc61bfe79d 100644
--- a/arch/arm64/crypto/chacha-neon-glue.c
+++ b/arch/arm64/crypto/chacha-neon-glue.c
@@ -20,7 +20,7 @@ 
  */
 
 #include <crypto/algapi.h>
-#include <crypto/chacha.h>
+#include <crypto/internal/chacha.h>
 #include <crypto/internal/simd.h>
 #include <crypto/internal/skcipher.h>
 #include <linux/kernel.h>
diff --git a/arch/x86/crypto/chacha_glue.c b/arch/x86/crypto/chacha_glue.c
index 388f95a4ec24..bc62daa8dafd 100644
--- a/arch/x86/crypto/chacha_glue.c
+++ b/arch/x86/crypto/chacha_glue.c
@@ -7,7 +7,7 @@ 
  */
 
 #include <crypto/algapi.h>
-#include <crypto/chacha.h>
+#include <crypto/internal/chacha.h>
 #include <crypto/internal/simd.h>
 #include <crypto/internal/skcipher.h>
 #include <linux/kernel.h>
diff --git a/crypto/Kconfig b/crypto/Kconfig
index 70b4f7b238fc..153cdefcbd78 100644
--- a/crypto/Kconfig
+++ b/crypto/Kconfig
@@ -1393,6 +1393,7 @@  config CRYPTO_SALSA20
 
 config CRYPTO_CHACHA20
 	tristate "ChaCha stream cipher algorithms"
+	select CRYPTO_LIB_CHACHA_GENERIC
 	select CRYPTO_BLKCIPHER
 	help
 	  The ChaCha20, XChaCha20, and XChaCha12 stream cipher algorithms.
diff --git a/crypto/chacha_generic.c b/crypto/chacha_generic.c
index 085d8d219987..ebae6d9d9b32 100644
--- a/crypto/chacha_generic.c
+++ b/crypto/chacha_generic.c
@@ -8,29 +8,10 @@ 
 
 #include <asm/unaligned.h>
 #include <crypto/algapi.h>
-#include <crypto/chacha.h>
+#include <crypto/internal/chacha.h>
 #include <crypto/internal/skcipher.h>
 #include <linux/module.h>
 
-static void chacha_docrypt(u32 *state, u8 *dst, const u8 *src,
-			   unsigned int bytes, int nrounds)
-{
-	/* aligned to potentially speed up crypto_xor() */
-	u8 stream[CHACHA_BLOCK_SIZE] __aligned(sizeof(long));
-
-	while (bytes >= CHACHA_BLOCK_SIZE) {
-		chacha_block(state, stream, nrounds);
-		crypto_xor_cpy(dst, src, stream, CHACHA_BLOCK_SIZE);
-		bytes -= CHACHA_BLOCK_SIZE;
-		dst += CHACHA_BLOCK_SIZE;
-		src += CHACHA_BLOCK_SIZE;
-	}
-	if (bytes) {
-		chacha_block(state, stream, nrounds);
-		crypto_xor_cpy(dst, src, stream, bytes);
-	}
-}
-
 static int chacha_stream_xor(struct skcipher_request *req,
 			     const struct chacha_ctx *ctx, const u8 *iv)
 {
@@ -48,8 +29,8 @@  static int chacha_stream_xor(struct skcipher_request *req,
 		if (nbytes < walk.total)
 			nbytes = round_down(nbytes, CHACHA_BLOCK_SIZE);
 
-		chacha_docrypt(state, walk.dst.virt.addr, walk.src.virt.addr,
-			       nbytes, ctx->nrounds);
+		chacha_crypt_generic(state, walk.dst.virt.addr,
+				     walk.src.virt.addr, nbytes, ctx->nrounds);
 		err = skcipher_walk_done(&walk, walk.nbytes - nbytes);
 	}
 
@@ -58,41 +39,10 @@  static int chacha_stream_xor(struct skcipher_request *req,
 
 void crypto_chacha_init(u32 *state, const struct chacha_ctx *ctx, const u8 *iv)
 {
-	state[0]  = 0x61707865; /* "expa" */
-	state[1]  = 0x3320646e; /* "nd 3" */
-	state[2]  = 0x79622d32; /* "2-by" */
-	state[3]  = 0x6b206574; /* "te k" */
-	state[4]  = ctx->key[0];
-	state[5]  = ctx->key[1];
-	state[6]  = ctx->key[2];
-	state[7]  = ctx->key[3];
-	state[8]  = ctx->key[4];
-	state[9]  = ctx->key[5];
-	state[10] = ctx->key[6];
-	state[11] = ctx->key[7];
-	state[12] = get_unaligned_le32(iv +  0);
-	state[13] = get_unaligned_le32(iv +  4);
-	state[14] = get_unaligned_le32(iv +  8);
-	state[15] = get_unaligned_le32(iv + 12);
+	chacha_init_generic(state, ctx->key, iv);
 }
 EXPORT_SYMBOL_GPL(crypto_chacha_init);
 
-static int chacha_setkey(struct crypto_skcipher *tfm, const u8 *key,
-			 unsigned int keysize, int nrounds)
-{
-	struct chacha_ctx *ctx = crypto_skcipher_ctx(tfm);
-	int i;
-
-	if (keysize != CHACHA_KEY_SIZE)
-		return -EINVAL;
-
-	for (i = 0; i < ARRAY_SIZE(ctx->key); i++)
-		ctx->key[i] = get_unaligned_le32(key + i * sizeof(u32));
-
-	ctx->nrounds = nrounds;
-	return 0;
-}
-
 int crypto_chacha20_setkey(struct crypto_skcipher *tfm, const u8 *key,
 			   unsigned int keysize)
 {
@@ -126,7 +76,7 @@  int crypto_xchacha_crypt(struct skcipher_request *req)
 
 	/* Compute the subkey given the original key and first 128 nonce bits */
 	crypto_chacha_init(state, ctx, req->iv);
-	hchacha_block(state, subctx.key, ctx->nrounds);
+	hchacha_block_generic(state, subctx.key, ctx->nrounds);
 	subctx.nrounds = ctx->nrounds;
 
 	/* Build the real IV */
diff --git a/include/crypto/chacha.h b/include/crypto/chacha.h
index d1e723c6a37d..78cb9d549b1b 100644
--- a/include/crypto/chacha.h
+++ b/include/crypto/chacha.h
@@ -15,9 +15,8 @@ 
 #ifndef _CRYPTO_CHACHA_H
 #define _CRYPTO_CHACHA_H
 
-#include <crypto/skcipher.h>
+#include <asm/unaligned.h>
 #include <linux/types.h>
-#include <linux/crypto.h>
 
 /* 32-bit stream position, then 96-bit nonce (RFC7539 convention) */
 #define CHACHA_IV_SIZE		16
@@ -29,26 +28,64 @@ 
 /* 192-bit nonce, then 64-bit stream position */
 #define XCHACHA_IV_SIZE		32
 
-struct chacha_ctx {
-	u32 key[8];
-	int nrounds;
-};
-
-void chacha_block(u32 *state, u8 *stream, int nrounds);
+void chacha_block_generic(u32 *state, u8 *stream, int nrounds);
 static inline void chacha20_block(u32 *state, u8 *stream)
 {
-	chacha_block(state, stream, 20);
+	chacha_block_generic(state, stream, 20);
+}
+
+void hchacha_block_arch(const u32 *state, u32 *out, int nrounds);
+void hchacha_block_generic(const u32 *state, u32 *out, int nrounds);
+
+static inline void hchacha_block(const u32 *state, u32 *out, int nrounds)
+{
+	if (IS_ENABLED(CONFIG_CRYPTO_ARCH_HAVE_LIB_CHACHA))
+		hchacha_block_arch(state, out, nrounds);
+	else
+		hchacha_block_generic(state, out, nrounds);
+}
+
+void chacha_init_arch(u32 *state, const u32 *key, const u8 *iv);
+static inline void chacha_init_generic(u32 *state, const u32 *key, const u8 *iv)
+{
+	state[0]  = 0x61707865; /* "expa" */
+	state[1]  = 0x3320646e; /* "nd 3" */
+	state[2]  = 0x79622d32; /* "2-by" */
+	state[3]  = 0x6b206574; /* "te k" */
+	state[4]  = key[0];
+	state[5]  = key[1];
+	state[6]  = key[2];
+	state[7]  = key[3];
+	state[8]  = key[4];
+	state[9]  = key[5];
+	state[10] = key[6];
+	state[11] = key[7];
+	state[12] = get_unaligned_le32(iv +  0);
+	state[13] = get_unaligned_le32(iv +  4);
+	state[14] = get_unaligned_le32(iv +  8);
+	state[15] = get_unaligned_le32(iv + 12);
 }
-void hchacha_block(const u32 *in, u32 *out, int nrounds);
 
-void crypto_chacha_init(u32 *state, const struct chacha_ctx *ctx, const u8 *iv);
+static inline void chacha_init(u32 *state, const u32 *key, const u8 *iv)
+{
+	if (IS_ENABLED(CONFIG_CRYPTO_ARCH_HAVE_LIB_CHACHA))
+		chacha_init_arch(state, key, iv);
+	else
+		chacha_init_generic(state, key, iv);
+}
 
-int crypto_chacha20_setkey(struct crypto_skcipher *tfm, const u8 *key,
-			   unsigned int keysize);
-int crypto_chacha12_setkey(struct crypto_skcipher *tfm, const u8 *key,
-			   unsigned int keysize);
+void chacha_crypt_arch(u32 *state, u8 *dst, const u8 *src,
+		       unsigned int bytes, int nrounds);
+void chacha_crypt_generic(u32 *state, u8 *dst, const u8 *src,
+			  unsigned int bytes, int nrounds);
 
-int crypto_chacha_crypt(struct skcipher_request *req);
-int crypto_xchacha_crypt(struct skcipher_request *req);
+static inline void chacha_crypt(u32 *state, u8 *dst, const u8 *src,
+				unsigned int bytes, int nrounds)
+{
+	if (IS_ENABLED(CONFIG_CRYPTO_ARCH_HAVE_LIB_CHACHA))
+		chacha_crypt_arch(state, dst, src, bytes, nrounds);
+	else
+		chacha_crypt_generic(state, dst, src, bytes, nrounds);
+}
 
 #endif /* _CRYPTO_CHACHA_H */
diff --git a/include/crypto/internal/chacha.h b/include/crypto/internal/chacha.h
new file mode 100644
index 000000000000..8724545bc959
--- /dev/null
+++ b/include/crypto/internal/chacha.h
@@ -0,0 +1,41 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef _CRYPTO_INTERNAL_CHACHA_H
+#define _CRYPTO_INTERNAL_CHACHA_H
+
+#include <crypto/chacha.h>
+#include <crypto/internal/skcipher.h>
+#include <linux/crypto.h>
+
+struct chacha_ctx {
+	u32 key[8];
+	int nrounds;
+};
+
+void crypto_chacha_init(u32 *state, const struct chacha_ctx *ctx, const u8 *iv);
+
+static inline int chacha_setkey(struct crypto_skcipher *tfm, const u8 *key,
+				unsigned int keysize, int nrounds)
+{
+	struct chacha_ctx *ctx = crypto_skcipher_ctx(tfm);
+	int i;
+
+	if (keysize != CHACHA_KEY_SIZE)
+		return -EINVAL;
+
+	for (i = 0; i < ARRAY_SIZE(ctx->key); i++)
+		ctx->key[i] = get_unaligned_le32(key + i * sizeof(u32));
+
+	ctx->nrounds = nrounds;
+	return 0;
+}
+
+int crypto_chacha20_setkey(struct crypto_skcipher *tfm, const u8 *key,
+			   unsigned int keysize);
+int crypto_chacha12_setkey(struct crypto_skcipher *tfm, const u8 *key,
+			   unsigned int keysize);
+
+int crypto_chacha_crypt(struct skcipher_request *req);
+int crypto_xchacha_crypt(struct skcipher_request *req);
+
+#endif /* _CRYPTO_CHACHA_H */
diff --git a/lib/Makefile b/lib/Makefile
index c5892807e06f..5af38fd5cc60 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -26,8 +26,7 @@  endif
 
 lib-y := ctype.o string.o vsprintf.o cmdline.o \
 	 rbtree.o radix-tree.o timerqueue.o xarray.o \
-	 idr.o extable.o \
-	 sha1.o chacha.o irq_regs.o argv_split.o \
+	 idr.o extable.o sha1.o irq_regs.o argv_split.o \
 	 flex_proportions.o ratelimit.o show_mem.o \
 	 is_single_threaded.o plist.o decompress.o kobject_uevent.o \
 	 earlycpio.o seq_buf.o siphash.o dec_and_lock.o \
diff --git a/lib/crypto/Kconfig b/lib/crypto/Kconfig
index 261430051595..6a11931ae105 100644
--- a/lib/crypto/Kconfig
+++ b/lib/crypto/Kconfig
@@ -8,6 +8,32 @@  config CRYPTO_LIB_AES
 config CRYPTO_LIB_ARC4
 	tristate
 
+config CRYPTO_ARCH_HAVE_LIB_CHACHA
+	tristate
+	help
+	  Declares whether the architecture provides an arch-specific
+	  accelerated implementation of the ChaCha library interface,
+	  either builtin or as a module.
+
+config CRYPTO_LIB_CHACHA_GENERIC
+	tristate
+	select CRYPTO_ALGAPI
+	help
+	  This symbol can be depended upon by arch implementations of the
+	  ChaCha library interface that require the generic code as a
+	  fallback, e.g., for SIMD implementations. If no arch specific
+	  implementation is enabled, this implementation serves the users
+	  of CRYPTO_LIB_CHACHA.
+
+config CRYPTO_LIB_CHACHA
+	tristate "ChaCha library interface"
+	depends on CRYPTO_ARCH_HAVE_LIB_CHACHA || !CRYPTO_ARCH_HAVE_LIB_CHACHA
+	select CRYPTO_LIB_CHACHA_GENERIC if CRYPTO_ARCH_HAVE_LIB_CHACHA=n
+	help
+	  Enable the ChaCha library interface. This interface may be fulfilled
+	  by either the generic implementation or an arch-specific one, if one
+	  is available and enabled.
+
 config CRYPTO_LIB_DES
 	tristate
 
diff --git a/lib/crypto/Makefile b/lib/crypto/Makefile
index 63de4cb3fcf8..0ce40604e104 100644
--- a/lib/crypto/Makefile
+++ b/lib/crypto/Makefile
@@ -1,5 +1,9 @@ 
 # SPDX-License-Identifier: GPL-2.0
 
+# chacha is used by the /dev/random driver which is always builtin
+obj-y						+= chacha.o
+obj-$(CONFIG_CRYPTO_LIB_CHACHA_GENERIC)		+= libchacha.o
+
 obj-$(CONFIG_CRYPTO_LIB_AES)			+= libaes.o
 libaes-y					:= aes.o
 
diff --git a/lib/chacha.c b/lib/crypto/chacha.c
similarity index 88%
rename from lib/chacha.c
rename to lib/crypto/chacha.c
index c7c9826564d3..65ead6b0c7e0 100644
--- a/lib/chacha.c
+++ b/lib/crypto/chacha.c
@@ -5,9 +5,11 @@ 
  * Copyright (C) 2015 Martin Willi
  */
 
+#include <linux/bug.h>
 #include <linux/kernel.h>
 #include <linux/export.h>
 #include <linux/bitops.h>
+#include <linux/string.h>
 #include <linux/cryptohash.h>
 #include <asm/unaligned.h>
 #include <crypto/chacha.h>
@@ -72,7 +74,7 @@  static void chacha_permute(u32 *x, int nrounds)
  * The caller has already converted the endianness of the input.  This function
  * also handles incrementing the block counter in the input matrix.
  */
-void chacha_block(u32 *state, u8 *stream, int nrounds)
+void chacha_block_generic(u32 *state, u8 *stream, int nrounds)
 {
 	u32 x[16];
 	int i;
@@ -86,11 +88,11 @@  void chacha_block(u32 *state, u8 *stream, int nrounds)
 
 	state[12]++;
 }
-EXPORT_SYMBOL(chacha_block);
+EXPORT_SYMBOL(chacha_block_generic);
 
 /**
- * hchacha_block - abbreviated ChaCha core, for XChaCha
- * @in: input state matrix (16 32-bit words)
+ * hchacha_block_generic - abbreviated ChaCha core, for XChaCha
+ * @state: input state matrix (16 32-bit words)
  * @out: output (8 32-bit words)
  * @nrounds: number of rounds (20 or 12; 20 is recommended)
  *
@@ -99,15 +101,15 @@  EXPORT_SYMBOL(chacha_block);
  * skips the final addition of the initial state, and outputs only certain words
  * of the state.  It should not be used for streaming directly.
  */
-void hchacha_block(const u32 *in, u32 *out, int nrounds)
+void hchacha_block_generic(const u32 *state, u32 *stream, int nrounds)
 {
 	u32 x[16];
 
-	memcpy(x, in, 64);
+	memcpy(x, state, 64);
 
 	chacha_permute(x, nrounds);
 
-	memcpy(&out[0], &x[0], 16);
-	memcpy(&out[4], &x[12], 16);
+	memcpy(&stream[0], &x[0], 16);
+	memcpy(&stream[4], &x[12], 16);
 }
-EXPORT_SYMBOL(hchacha_block);
+EXPORT_SYMBOL(hchacha_block_generic);
diff --git a/lib/crypto/libchacha.c b/lib/crypto/libchacha.c
new file mode 100644
index 000000000000..7b4b97811f71
--- /dev/null
+++ b/lib/crypto/libchacha.c
@@ -0,0 +1,35 @@ 
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * The "hash function" used as the core of the ChaCha stream cipher (RFC7539)
+ *
+ * Copyright (C) 2015 Martin Willi
+ */
+
+#include <linux/kernel.h>
+#include <linux/export.h>
+#include <linux/module.h>
+
+#include <crypto/algapi.h> // for crypto_xor_cpy
+#include <crypto/chacha.h>
+
+void chacha_crypt_generic(u32 *state, u8 *dst, const u8 *src,
+			  unsigned int bytes, int nrounds)
+{
+	/* aligned to potentially speed up crypto_xor() */
+	u8 stream[CHACHA_BLOCK_SIZE] __aligned(sizeof(long));
+
+	while (bytes >= CHACHA_BLOCK_SIZE) {
+		chacha_block_generic(state, stream, nrounds);
+		crypto_xor_cpy(dst, src, stream, CHACHA_BLOCK_SIZE);
+		bytes -= CHACHA_BLOCK_SIZE;
+		dst += CHACHA_BLOCK_SIZE;
+		src += CHACHA_BLOCK_SIZE;
+	}
+	if (bytes) {
+		chacha_block_generic(state, stream, nrounds);
+		crypto_xor_cpy(dst, src, stream, bytes);
+	}
+}
+EXPORT_SYMBOL(chacha_crypt_generic);
+
+MODULE_LICENSE("GPL");