ext4: move halfmd4 into hash.c directly

The "half md4" transform should not be used by any new code. And
fortunately, it's only used now by ext4. Since ext4 supports several
hashing methods, at some point it might be desirable to move to
something like SipHash. As an intermediate step, remove half md4 from
cryptohash.h and lib, and make it just a local function in ext4's
hash.c. There's precedent for doing this; the other function ext can use
for its hashes -- TEA -- is also implemented in the same place. Also, by
being a local function, this might allow gcc to perform some additional
optimizations.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

2 files changed, 1 insertions, 68 deletions

diff --git a/lib/Makefile b/lib/Makefile
index bc4073a8cd08..19ea76149a37 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -31,7 +31,7 @@ lib-$(CONFIG_HAS_DMA) += dma-noop.o
 lib-y	+= kobject.o klist.o
 obj-y	+= lockref.o
 
-obj-y += bcd.o div64.o sort.o parser.o halfmd4.o debug_locks.o random32.o \
+obj-y += bcd.o div64.o sort.o parser.o debug_locks.o random32.o \
 	 bust_spinlocks.o kasprintf.o bitmap.o scatterlist.o \
 	 gcd.o lcm.o list_sort.o uuid.o flex_array.o iov_iter.o clz_ctz.o \
 	 bsearch.o find_bit.o llist.o memweight.o kfifo.o \
diff --git a/lib/halfmd4.c b/lib/halfmd4.c
deleted file mode 100644
index 137e861d9690..000000000000
--- a/lib/halfmd4.c
+++ /dev/null
@@ -1,67 +0,0 @@
-#include <linux/compiler.h>
-#include <linux/export.h>
-#include <linux/cryptohash.h>
-#include <linux/bitops.h>
-
-/* F, G and H are basic MD4 functions: selection, majority, parity */
-#define F(x, y, z) ((z) ^ ((x) & ((y) ^ (z))))
-#define G(x, y, z) (((x) & (y)) + (((x) ^ (y)) & (z)))
-#define H(x, y, z) ((x) ^ (y) ^ (z))
-
-/*
- * The generic round function.  The application is so specific that
- * we don't bother protecting all the arguments with parens, as is generally
- * good macro practice, in favor of extra legibility.
- * Rotation is separate from addition to prevent recomputation
- */
-#define ROUND(f, a, b, c, d, x, s)	\
-	(a += f(b, c, d) + x, a = rol32(a, s))
-#define K1 0
-#define K2 013240474631UL
-#define K3 015666365641UL
-
-/*
- * Basic cut-down MD4 transform.  Returns only 32 bits of result.
- */
-__u32 half_md4_transform(__u32 buf[4], __u32 const in[8])
-{
-	__u32 a = buf[0], b = buf[1], c = buf[2], d = buf[3];
-
-	/* Round 1 */
-	ROUND(F, a, b, c, d, in[0] + K1,  3);
-	ROUND(F, d, a, b, c, in[1] + K1,  7);
-	ROUND(F, c, d, a, b, in[2] + K1, 11);
-	ROUND(F, b, c, d, a, in[3] + K1, 19);
-	ROUND(F, a, b, c, d, in[4] + K1,  3);
-	ROUND(F, d, a, b, c, in[5] + K1,  7);
-	ROUND(F, c, d, a, b, in[6] + K1, 11);
-	ROUND(F, b, c, d, a, in[7] + K1, 19);
-
-	/* Round 2 */
-	ROUND(G, a, b, c, d, in[1] + K2,  3);
-	ROUND(G, d, a, b, c, in[3] + K2,  5);
-	ROUND(G, c, d, a, b, in[5] + K2,  9);
-	ROUND(G, b, c, d, a, in[7] + K2, 13);
-	ROUND(G, a, b, c, d, in[0] + K2,  3);
-	ROUND(G, d, a, b, c, in[2] + K2,  5);
-	ROUND(G, c, d, a, b, in[4] + K2,  9);
-	ROUND(G, b, c, d, a, in[6] + K2, 13);
-
-	/* Round 3 */
-	ROUND(H, a, b, c, d, in[3] + K3,  3);
-	ROUND(H, d, a, b, c, in[7] + K3,  9);
-	ROUND(H, c, d, a, b, in[2] + K3, 11);
-	ROUND(H, b, c, d, a, in[6] + K3, 15);
-	ROUND(H, a, b, c, d, in[1] + K3,  3);
-	ROUND(H, d, a, b, c, in[5] + K3,  9);
-	ROUND(H, c, d, a, b, in[0] + K3, 11);
-	ROUND(H, b, c, d, a, in[4] + K3, 15);
-
-	buf[0] += a;
-	buf[1] += b;
-	buf[2] += c;
-	buf[3] += d;
-
-	return buf[1]; /* "most hashed" word */
-}
-EXPORT_SYMBOL(half_md4_transform);