Add linux sha2 support

The upstream ZFS code has correctly moved to a faster native sha2
implementation.  Unfortunately, under Linux that's going to be a little
problematic so we revert the code to the more portable version contained
in earlier ZFS releases.  Using the native sha2 implementation in Linux
is possible but the API is slightly different in kernel version user
space depending on which libraries are used.  Ideally, we need a fast
implementation of SHA256 which builds as part of ZFS this shouldn't be
that hard to do but it will take some effort.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>

lib/libzfs/libzfs_sendrecv.c

@@ -43,7 +43,6 @@
 #include "zfs_prop.h"
 #include "zfs_fletcher.h"
 #include "libzfs_impl.h"
-#include <sha2.h>
 #include <sys/zio_checksum.h>
 #include <sys/ddt.h>
 
@@ -336,12 +335,11 @@ cksummer(void *arg)
 			if (ZIO_CHECKSUM_EQUAL(drrw->drr_key.ddk_cksum,
 			    zero_cksum) ||
 			    !DRR_IS_DEDUP_CAPABLE(drrw->drr_checksumflags)) {
-				SHA256_CTX	ctx;
-				zio_cksum_t	tmpsha256;
+				zio_cksum_t tmpsha256;
+
+				zio_checksum_SHA256(buf,
+				    drrw->drr_length, &tmpsha256);
 
-				SHA256Init(&ctx);
-				SHA256Update(&ctx, buf, drrw->drr_length);
-				SHA256Final(&tmpsha256, &ctx);
 				drrw->drr_key.ddk_cksum.zc_word[0] =
 				    BE_64(tmpsha256.zc_word[0]);
 				drrw->drr_key.ddk_cksum.zc_word[1] =

module/zfs/sha256.c

@@ -19,32 +19,109 @@
  * CDDL HEADER END
  */
 /*
- * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
+ * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
  * Use is subject to license terms.
  */
+
 #include <sys/zfs_context.h>
 #include <sys/zio.h>
-#include <sys/sha2.h>
+#include <sys/zio_checksum.h>
+
+/*
+ * SHA-256 checksum, as specified in FIPS 180-3, available at:
+ * http://csrc.nist.gov/publications/PubsFIPS.html
+ *
+ * This is a very compact implementation of SHA-256.
+ * It is designed to be simple and portable, not to be fast.
+ */
+
+/*
+ * The literal definitions of Ch() and Maj() according to FIPS 180-3 are:
+ *
+ * 	Ch(x, y, z)     (x & y) ^ (~x & z)
+ * 	Maj(x, y, z)    (x & y) ^ (x & z) ^ (y & z)
+ *
+ * We use equivalent logical reductions here that require one less op.
+ */
+#define	Ch(x, y, z)	((z) ^ ((x) & ((y) ^ (z))))
+#define	Maj(x, y, z)	(((x) & (y)) ^ ((z) & ((x) ^ (y))))
+#define	Rot32(x, s)	(((x) >> s) | ((x) << (32 - s)))
+#define	SIGMA0(x)	(Rot32(x, 2) ^ Rot32(x, 13) ^ Rot32(x, 22))
+#define	SIGMA1(x)	(Rot32(x, 6) ^ Rot32(x, 11) ^ Rot32(x, 25))
+#define	sigma0(x)	(Rot32(x, 7) ^ Rot32(x, 18) ^ ((x) >> 3))
+#define	sigma1(x)	(Rot32(x, 17) ^ Rot32(x, 19) ^ ((x) >> 10))
+
+static const uint32_t SHA256_K[64] = {
+	0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5,
+	0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
+	0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3,
+	0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
+	0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc,
+	0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
+	0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7,
+	0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
+	0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13,
+	0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
+	0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3,
+	0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
+	0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5,
+	0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
+	0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208,
+	0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2
+};
+
+static void
+SHA256Transform(uint32_t *H, const uint8_t *cp)
+{
+	uint32_t a, b, c, d, e, f, g, h, t, T1, T2, W[64];
+
+	for (t = 0; t < 16; t++, cp += 4)
+		W[t] = (cp[0] << 24) | (cp[1] << 16) | (cp[2] << 8) | cp[3];
+
+	for (t = 16; t < 64; t++)
+		W[t] = sigma1(W[t - 2]) + W[t - 7] +
+		    sigma0(W[t - 15]) + W[t - 16];
+
+	a = H[0]; b = H[1]; c = H[2]; d = H[3];
+	e = H[4]; f = H[5]; g = H[6]; h = H[7];
+
+	for (t = 0; t < 64; t++) {
+		T1 = h + SIGMA1(e) + Ch(e, f, g) + SHA256_K[t] + W[t];
+		T2 = SIGMA0(a) + Maj(a, b, c);
+		h = g; g = f; f = e; e = d + T1;
+		d = c; c = b; b = a; a = T1 + T2;
+	}
+
+	H[0] += a; H[1] += b; H[2] += c; H[3] += d;
+	H[4] += e; H[5] += f; H[6] += g; H[7] += h;
+}
 
 void
 zio_checksum_SHA256(const void *buf, uint64_t size, zio_cksum_t *zcp)
 {
-	SHA2_CTX ctx;
-	zio_cksum_t tmp;
+	uint32_t H[8] = { 0x6a09e667, 0xbb67ae85, 0x3c6ef372, 0xa54ff53a,
+	    0x510e527f, 0x9b05688c, 0x1f83d9ab, 0x5be0cd19 };
+	uint8_t pad[128];
+	int i, padsize;
 
-	SHA2Init(SHA256, &ctx);
-	SHA2Update(&ctx, buf, size);
-	SHA2Final(&tmp, &ctx);
+	for (i = 0; i < (size & ~63ULL); i += 64)
+		SHA256Transform(H, (uint8_t *)buf + i);
 
-	/*
-	 * A prior implementation of this function had a
-	 * private SHA256 implementation always wrote things out in
-	 * Big Endian and there wasn't a byteswap variant of it.
-	 * To preseve on disk compatibility we need to force that
-	 * behaviour.
-	 */
-	zcp->zc_word[0] = BE_64(tmp.zc_word[0]);
-	zcp->zc_word[1] = BE_64(tmp.zc_word[1]);
-	zcp->zc_word[2] = BE_64(tmp.zc_word[2]);
-	zcp->zc_word[3] = BE_64(tmp.zc_word[3]);
+	for (padsize = 0; i < size; i++)
+		pad[padsize++] = *((uint8_t *)buf + i);
+
+	for (pad[padsize++] = 0x80; (padsize & 63) != 56; padsize++)
+		pad[padsize] = 0;
+
+	for (i = 56; i >= 0; i -= 8)
+		pad[padsize++] = (size << 3) >> i;
+
+	for (i = 0; i < padsize; i += 64)
+		SHA256Transform(H, pad + i);
+
+	ZIO_SET_CHECKSUM(zcp,
+	    (uint64_t)H[0] << 32 | H[1],
+	    (uint64_t)H[2] << 32 | H[3],
+	    (uint64_t)H[4] << 32 | H[5],
+	    (uint64_t)H[6] << 32 | H[7]);
 }