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as well, in a way that permits the implementation to be superseded by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@xxxxxxxxxx>
---
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(-)
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");
--
2.20.1
