1 files changed, 135 insertions, 0 deletions
diff --git a/lib/sha1.c b/lib/sha1.c
new file mode 100644
index 000000000..bad466954
--- /dev/null
+++ b/lib/sha1.c
@@ -0,0 +1,135 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * SHA1 routine optimized to do word accesses rather than byte accesses,
+ * and to avoid unnecessary copies into the context array.
+ *
+ * This was based on the git SHA1 implementation.
+ */
+
+#include <linux/kernel.h>
+#include <linux/export.h>
+#include <linux/bitops.h>
+#include <linux/cryptohash.h>
+#include <linux/string.h>
+#include <asm/unaligned.h>
+
+/*
+ * If you have 32 registers or more, the compiler can (and should)
+ * try to change the array[] accesses into registers. However, on
+ * machines with less than ~25 registers, that won't really work,
+ * and at least gcc will make an unholy mess of it.
+ *
+ * So to avoid that mess which just slows things down, we force
+ * the stores to memory to actually happen (we might be better off
+ * with a 'W(t)=(val);asm("":"+m" (W(t))' there instead, as
+ * suggested by Artur Skawina - that will also make gcc unable to
+ * try to do the silly "optimize away loads" part because it won't
+ * see what the value will be).
+ *
+ * Ben Herrenschmidt reports that on PPC, the C version comes close
+ * to the optimized asm with this (ie on PPC you don't want that
+ * 'volatile', since there are lots of registers).
+ *
+ * On ARM we get the best code generation by forcing a full memory barrier
+ * between each SHA_ROUND, otherwise gcc happily get wild with spilling and
+ * the stack frame size simply explode and performance goes down the drain.
+ */
+
+#ifdef CONFIG_X86
+  #define setW(x, val) (*(volatile __u32 *)&W(x) = (val))
+#elif defined(CONFIG_ARM)
+  #define setW(x, val) do { W(x) = (val); __asm__("":::"memory"); } while (0)
+#else
+  #define setW(x, val) (W(x) = (val))
+#endif
+
+/* This "rolls" over the 512-bit array */
+#define W(x) (array[(x)&15])
+
+/*
+ * Where do we get the source from? The first 16 iterations get it from
+ * the input data, the next mix it from the 512-bit array.
+ */
+#define SHA_SRC(t) get_unaligned_be32((__u32 *)data + t)
+#define SHA_MIX(t) rol32(W(t+13) ^ W(t+8) ^ W(t+2) ^ W(t), 1)
+
+#define SHA_ROUND(t, input, fn, constant, A, B, C, D, E) do { \
+	__u32 TEMP = input(t); setW(t, TEMP); \
+	E += TEMP + rol32(A,5) + (fn) + (constant); \
+	B = ror32(B, 2); \
+	TEMP = E; E = D; D = C; C = B; B = A; A = TEMP; } while (0)
+
+#define T_0_15(t, A, B, C, D, E)  SHA_ROUND(t, SHA_SRC, (((C^D)&B)^D) , 0x5a827999, A, B, C, D, E )
+#define T_16_19(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, (((C^D)&B)^D) , 0x5a827999, A, B, C, D, E )
+#define T_20_39(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, (B^C^D) , 0x6ed9eba1, A, B, C, D, E )
+#define T_40_59(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, ((B&C)+(D&(B^C))) , 0x8f1bbcdc, A, B, C, D, E )
+#define T_60_79(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, (B^C^D) ,  0xca62c1d6, A, B, C, D, E )
+
+/**
+ * sha_transform - single block SHA1 transform
+ *
+ * @digest: 160 bit digest to update
+ * @data:   512 bits of data to hash
+ * @array:  16 words of workspace (see note)
+ *
+ * This function generates a SHA1 digest for a single 512-bit block.
+ * Be warned, it does not handle padding and message digest, do not
+ * confuse it with the full FIPS 180-1 digest algorithm for variable
+ * length messages.
+ *
+ * Note: If the hash is security sensitive, the caller should be sure
+ * to clear the workspace. This is left to the caller to avoid
+ * unnecessary clears between chained hashing operations.
+ */
+void sha_transform(__u32 *digest, const char *data, __u32 *array)
+{
+	__u32 A, B, C, D, E;
+	unsigned int i = 0;
+
+	A = digest[0];
+	B = digest[1];
+	C = digest[2];
+	D = digest[3];
+	E = digest[4];
+
+	/* Round 1 - iterations 0-16 take their input from 'data' */
+	for (; i < 16; ++i)
+		T_0_15(i, A, B, C, D, E);
+
+	/* Round 1 - tail. Input from 512-bit mixing array */
+	for (; i < 20; ++i)
+		T_16_19(i, A, B, C, D, E);
+
+	/* Round 2 */
+	for (; i < 40; ++i)
+		T_20_39(i, A, B, C, D, E);
+
+	/* Round 3 */
+	for (; i < 60; ++i)
+		T_40_59(i, A, B, C, D, E);
+
+	/* Round 4 */
+	for (; i < 80; ++i)
+		T_60_79(i, A, B, C, D, E);
+
+	digest[0] += A;
+	digest[1] += B;
+	digest[2] += C;
+	digest[3] += D;
+	digest[4] += E;
+}
+EXPORT_SYMBOL(sha_transform);
+
+/**
+ * sha_init - initialize the vectors for a SHA1 digest
+ * @buf: vector to initialize
+ */
+void sha_init(__u32 *buf)
+{
+	buf[0] = 0x67452301;
+	buf[1] = 0xefcdab89;
+	buf[2] = 0x98badcfe;
+	buf[3] = 0x10325476;
+	buf[4] = 0xc3d2e1f0;
+}
+EXPORT_SYMBOL(sha_init);