summaryrefslogtreecommitdiffstats
path: root/lib
diff options
context:
space:
mode:
authorArd Biesheuvel <ardb@kernel.org>2019-11-08 13:22:08 +0100
committerHerbert Xu <herbert@gondor.apana.org.au>2019-11-17 09:02:39 +0800
commit5fb8ef25803ef33e2eb60b626435828b937bed75 (patch)
tree156401ad072c1acc18f74cbdf8eb31859191b9ac /lib
parent746b2e024c67aa605ac12d135cd7085a49cf9dc4 (diff)
downloadlinux-5fb8ef25803ef33e2eb60b626435828b937bed75.tar.bz2
crypto: chacha - move existing library code into lib/crypto
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API, let's expose the streamcipher bits via a library API as well, in a way that permits the implementation to be superseded by an architecture specific one if provided.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 <ardb@kernel.org> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Diffstat (limited to 'lib')
-rw-r--r--lib/Makefile3
-rw-r--r--lib/crypto/Kconfig26
-rw-r--r--lib/crypto/Makefile4
-rw-r--r--lib/crypto/chacha.c (renamed from lib/chacha.c)20
-rw-r--r--lib/crypto/libchacha.c35
5 files changed, 77 insertions, 11 deletions
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
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..dabc3accae05
--- /dev/null
+++ b/lib/crypto/libchacha.c
@@ -0,0 +1,35 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * 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");