[PATCH v3 2/3] crypto: lib - move __crypto_xor into utils

Eric Biggers
2022-07-25T18:36:59Z

From: Eric Biggers <ebiggers@google.com>

CRYPTO_LIB_CHACHA depends on CRYPTO for __crypto_xor, defined in
crypto/algapi.c. This is a layering violation because the dependencies
should only go in the other direction (crypto/ => lib/crypto/). Also
the correct dependency would be CRYPTO_ALGAPI, not CRYPTO. Fix this by
moving __crypto_xor into the utils module in lib/crypto/.

Note that CRYPTO_LIB_CHACHA_GENERIC selected XOR_BLOCKS, which is
unrelated and unnecessary. It was perhaps thought that XOR_BLOCKS was
needed for __crypto_xor, but that's not the case.

Signed-off-by: Eric Biggers <ebiggers@google.com>
---
crypto/algapi.c | 71 ------------------------------------
lib/crypto/Kconfig | 3 +-
lib/crypto/Makefile | 2 +-
lib/crypto/memneq.c | 2 --
lib/crypto/utils.c | 88 +++++++++++++++++++++++++++++++++++++++++++++
5 files changed, 90 insertions(+), 76 deletions(-)
create mode 100644 lib/crypto/utils.c

diff --git a/crypto/algapi.c b/crypto/algapi.c
index d1c99288af3e0d..5c69ff8e8fa5c1 100644
--- a/crypto/algapi.c
+++ b/crypto/algapi.c
@@ -997,77 +997,6 @@ void crypto_inc(u8 *a, unsigned int size)
}
EXPORT_SYMBOL_GPL(crypto_inc);

-void __crypto_xor(u8 *dst, const u8 *src1, const u8 *src2, unsigned int len)
-{
- int relalign = 0;
-
- if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) {
- int size = sizeof(unsigned long);
- int d = (((unsigned long)dst ^ (unsigned long)src1) |
- ((unsigned long)dst ^ (unsigned long)src2)) &
- (size - 1);
-
- relalign = d ? 1 << __ffs(d) : size;
-
- /*
- * If we care about alignment, process as many bytes as
- * needed to advance dst and src to values whose alignments
- * equal their relative alignment. This will allow us to
- * process the remainder of the input using optimal strides.
- */
- while (((unsigned long)dst & (relalign - 1)) && len > 0) {
- *dst++ = *src1++ ^ *src2++;
- len--;
- }
- }
-
- while (IS_ENABLED(CONFIG_64BIT) && len >= 8 && !(relalign & 7)) {
- if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) {
- u64 l = get_unaligned((u64 *)src1) ^
- get_unaligned((u64 *)src2);
- put_unaligned(l, (u64 *)dst);
- } else {
- *(u64 *)dst = *(u64 *)src1 ^ *(u64 *)src2;
- }
- dst += 8;
- src1 += 8;
- src2 += 8;
- len -= 8;
- }
-
- while (len >= 4 && !(relalign & 3)) {
- if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) {
- u32 l = get_unaligned((u32 *)src1) ^
- get_unaligned((u32 *)src2);
- put_unaligned(l, (u32 *)dst);
- } else {
- *(u32 *)dst = *(u32 *)src1 ^ *(u32 *)src2;
- }
- dst += 4;
- src1 += 4;
- src2 += 4;
- len -= 4;
- }
-
- while (len >= 2 && !(relalign & 1)) {
- if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) {
- u16 l = get_unaligned((u16 *)src1) ^
- get_unaligned((u16 *)src2);
- put_unaligned(l, (u16 *)dst);
- } else {
- *(u16 *)dst = *(u16 *)src1 ^ *(u16 *)src2;
- }
- dst += 2;
- src1 += 2;
- src2 += 2;
- len -= 2;
- }
-
- while (len--)
- *dst++ = *src1++ ^ *src2++;
-}
-EXPORT_SYMBOL_GPL(__crypto_xor);
-
unsigned int crypto_alg_extsize(struct crypto_alg *alg)
{
return alg->cra_ctxsize +
diff --git a/lib/crypto/Kconfig b/lib/crypto/Kconfig
index b09d9d6546cbc3..7e9683e9f5c636 100644
--- a/lib/crypto/Kconfig
+++ b/lib/crypto/Kconfig
@@ -36,7 +36,7 @@ config CRYPTO_ARCH_HAVE_LIB_CHACHA

config CRYPTO_LIB_CHACHA_GENERIC
tristate
- select XOR_BLOCKS
+ select CRYPTO_LIB_UTILS
help
This symbol can be depended upon by arch implementations of the
ChaCha library interface that require the generic code as a
@@ -46,7 +46,6 @@ config CRYPTO_LIB_CHACHA_GENERIC

config CRYPTO_LIB_CHACHA
tristate "ChaCha library interface"
- depends on CRYPTO
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
diff --git a/lib/crypto/Makefile b/lib/crypto/Makefile
index b956b3bae26aaf..c852f067ab0601 100644
--- a/lib/crypto/Makefile
+++ b/lib/crypto/Makefile
@@ -1,7 +1,7 @@
# SPDX-License-Identifier: GPL-2.0

obj-$(CONFIG_CRYPTO_LIB_UTILS) += libcryptoutils.o
-libcryptoutils-y := memneq.o
+libcryptoutils-y := memneq.o utils.o

# chacha is used by the /dev/random driver which is always builtin
obj-y += chacha.o
diff --git a/lib/crypto/memneq.c b/lib/crypto/memneq.c
index f2098318428478..d1e8c86fbb0fcf 100644
--- a/lib/crypto/memneq.c
+++ b/lib/crypto/memneq.c
@@ -175,5 +175,3 @@ noinline unsigned long __crypto_memneq(const void *a, const void *b,
EXPORT_SYMBOL(__crypto_memneq);

#endif /* __HAVE_ARCH_CRYPTO_MEMNEQ */
-
-MODULE_LICENSE("GPL");
diff --git a/lib/crypto/utils.c b/lib/crypto/utils.c
new file mode 100644
index 00000000000000..53230ab1b19576
--- /dev/null
+++ b/lib/crypto/utils.c
@@ -0,0 +1,88 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Crypto library utility functions
+ *
+ * Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au>
+ */
+
+#include <asm/unaligned.h>
+#include <crypto/algapi.h>
+#include <linux/module.h>
+
+/*
+ * XOR @len bytes from @src1 and @src2 together, writing the result to @dst
+ * (which may alias one of the sources). Don't call this directly; call
+ * crypto_xor() or crypto_xor_cpy() instead.
+ */
+void __crypto_xor(u8 *dst, const u8 *src1, const u8 *src2, unsigned int len)
+{
+ int relalign = 0;
+
+ if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) {
+ int size = sizeof(unsigned long);
+ int d = (((unsigned long)dst ^ (unsigned long)src1) |
+ ((unsigned long)dst ^ (unsigned long)src2)) &
+ (size - 1);
+
+ relalign = d ? 1 << __ffs(d) : size;
+
+ /*
+ * If we care about alignment, process as many bytes as
+ * needed to advance dst and src to values whose alignments
+ * equal their relative alignment. This will allow us to
+ * process the remainder of the input using optimal strides.
+ */
+ while (((unsigned long)dst & (relalign - 1)) && len > 0) {
+ *dst++ = *src1++ ^ *src2++;
+ len--;
+ }
+ }
+
+ while (IS_ENABLED(CONFIG_64BIT) && len >= 8 && !(relalign & 7)) {
+ if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) {
+ u64 l = get_unaligned((u64 *)src1) ^
+ get_unaligned((u64 *)src2);
+ put_unaligned(l, (u64 *)dst);
+ } else {
+ *(u64 *)dst = *(u64 *)src1 ^ *(u64 *)src2;
+ }
+ dst += 8;
+ src1 += 8;
+ src2 += 8;
+ len -= 8;
+ }
+
+ while (len >= 4 && !(relalign & 3)) {
+ if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) {
+ u32 l = get_unaligned((u32 *)src1) ^
+ get_unaligned((u32 *)src2);
+ put_unaligned(l, (u32 *)dst);
+ } else {
+ *(u32 *)dst = *(u32 *)src1 ^ *(u32 *)src2;
+ }
+ dst += 4;
+ src1 += 4;
+ src2 += 4;
+ len -= 4;
+ }
+
+ while (len >= 2 && !(relalign & 1)) {
+ if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) {
+ u16 l = get_unaligned((u16 *)src1) ^
+ get_unaligned((u16 *)src2);
+ put_unaligned(l, (u16 *)dst);
+ } else {
+ *(u16 *)dst = *(u16 *)src1 ^ *(u16 *)src2;
+ }
+ dst += 2;
+ src1 += 2;
+ src2 += 2;
+ len -= 2;
+ }
+
+ while (len--)
+ *dst++ = *src1++ ^ *src2++;
+}
+EXPORT_SYMBOL_GPL(__crypto_xor);
+
+MODULE_LICENSE("GPL");
--
2.37.0