[PATCH 2/4] erofs-utils: introduce sha256

[Gao Xiang <hsiangkao@linux.alibaba.com>]

A simple sha256 approach copied from e2fsprogs.

Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
---
 lib/Makefile.am |   2 +-
 lib/sha256.c    | 248 ++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 249 insertions(+), 1 deletion(-)
 create mode 100644 lib/sha256.c

diff --git a/lib/Makefile.am b/lib/Makefile.am
index 0768d6aa5871..8e4ed37f9c70 100644
--- a/lib/Makefile.am
+++ b/lib/Makefile.am
@@ -22,7 +22,7 @@ noinst_HEADERS = $(top_srcdir)/include/erofs_fs.h \
 noinst_HEADERS += compressor.h
 liberofs_la_SOURCES = config.c io.c cache.c super.c inode.c xattr.c exclude.c \
 		      namei.c data.c compress.c compressor.c zmap.c decompress.c \
-		      hashmap.c
+		      hashmap.c sha256.c
 liberofs_la_CFLAGS = -Wall -Werror -I$(top_srcdir)/include
 if ENABLE_LZ4
 liberofs_la_CFLAGS += ${LZ4_CFLAGS}
diff --git a/lib/sha256.c b/lib/sha256.c
new file mode 100644
index 000000000000..68e039ab9c91
--- /dev/null
+++ b/lib/sha256.c
@@ -0,0 +1,248 @@
+/*
+ * sha256.c --- The sha256 algorithm
+ *
+ * Copyright (C) 2004 Sam Hocevar <sam@hocevar.net>
+ * (copied from libtomcrypt and then relicensed under GPLv2)
+ *
+ * %Begin-Header%
+ * This file may be redistributed under the terms of the GNU Library
+ * General Public License, version 2.
+ * %End-Header%
+ */
+#include "erofs/defs.h"
+#include <string.h>
+
+static const __u32 K[64] = {
+    0x428a2f98UL, 0x71374491UL, 0xb5c0fbcfUL, 0xe9b5dba5UL, 0x3956c25bUL,
+    0x59f111f1UL, 0x923f82a4UL, 0xab1c5ed5UL, 0xd807aa98UL, 0x12835b01UL,
+    0x243185beUL, 0x550c7dc3UL, 0x72be5d74UL, 0x80deb1feUL, 0x9bdc06a7UL,
+    0xc19bf174UL, 0xe49b69c1UL, 0xefbe4786UL, 0x0fc19dc6UL, 0x240ca1ccUL,
+    0x2de92c6fUL, 0x4a7484aaUL, 0x5cb0a9dcUL, 0x76f988daUL, 0x983e5152UL,
+    0xa831c66dUL, 0xb00327c8UL, 0xbf597fc7UL, 0xc6e00bf3UL, 0xd5a79147UL,
+    0x06ca6351UL, 0x14292967UL, 0x27b70a85UL, 0x2e1b2138UL, 0x4d2c6dfcUL,
+    0x53380d13UL, 0x650a7354UL, 0x766a0abbUL, 0x81c2c92eUL, 0x92722c85UL,
+    0xa2bfe8a1UL, 0xa81a664bUL, 0xc24b8b70UL, 0xc76c51a3UL, 0xd192e819UL,
+    0xd6990624UL, 0xf40e3585UL, 0x106aa070UL, 0x19a4c116UL, 0x1e376c08UL,
+    0x2748774cUL, 0x34b0bcb5UL, 0x391c0cb3UL, 0x4ed8aa4aUL, 0x5b9cca4fUL,
+    0x682e6ff3UL, 0x748f82eeUL, 0x78a5636fUL, 0x84c87814UL, 0x8cc70208UL,
+    0x90befffaUL, 0xa4506cebUL, 0xbef9a3f7UL, 0xc67178f2UL
+};
+
+/* Various logical functions */
+#define Ch(x,y,z)       (z ^ (x & (y ^ z)))
+#define Maj(x,y,z)      (((x | y) & z) | (x & y))
+#define S(x, n)         RORc((x),(n))
+#define R(x, n)         (((x)&0xFFFFFFFFUL)>>(n))
+#define Sigma0(x)       (S(x, 2) ^ S(x, 13) ^ S(x, 22))
+#define Sigma1(x)       (S(x, 6) ^ S(x, 11) ^ S(x, 25))
+#define Gamma0(x)       (S(x, 7) ^ S(x, 18) ^ R(x, 3))
+#define Gamma1(x)       (S(x, 17) ^ S(x, 19) ^ R(x, 10))
+#define RORc(x, y) ( ((((__u32)(x)&0xFFFFFFFFUL)>>(__u32)((y)&31)) | ((__u32)(x)<<(__u32)(32-((y)&31)))) & 0xFFFFFFFFUL)
+
+#define RND(a,b,c,d,e,f,g,h,i)                         \
+     t0 = h + Sigma1(e) + Ch(e, f, g) + K[i] + W[i];   \
+     t1 = Sigma0(a) + Maj(a, b, c);                    \
+     d += t0;                                          \
+     h  = t0 + t1;
+
+#define STORE64H(x, y) \
+	do { \
+		(y)[0] = (unsigned char)(((x)>>56)&255);\
+		(y)[1] = (unsigned char)(((x)>>48)&255);\
+		(y)[2] = (unsigned char)(((x)>>40)&255);\
+		(y)[3] = (unsigned char)(((x)>>32)&255);\
+		(y)[4] = (unsigned char)(((x)>>24)&255);\
+		(y)[5] = (unsigned char)(((x)>>16)&255);\
+		(y)[6] = (unsigned char)(((x)>>8)&255);\
+		(y)[7] = (unsigned char)((x)&255); } while(0)
+
+#define STORE32H(x, y)                                                                     \
+  do { (y)[0] = (unsigned char)(((x)>>24)&255); (y)[1] = (unsigned char)(((x)>>16)&255);   \
+       (y)[2] = (unsigned char)(((x)>>8)&255); (y)[3] = (unsigned char)((x)&255); } while(0)
+
+#define LOAD32H(x, y)                            \
+  do { x = ((__u32)((y)[0] & 255)<<24) | \
+           ((__u32)((y)[1] & 255)<<16) | \
+           ((__u32)((y)[2] & 255)<<8)  | \
+           ((__u32)((y)[3] & 255)); } while(0)
+
+struct sha256_state {
+    __u64 length;
+    __u32 state[8], curlen;
+    unsigned char buf[64];
+};
+
+/* This is a highly simplified version from libtomcrypt */
+struct hash_state {
+	struct sha256_state sha256;
+};
+
+static void sha256_compress(struct hash_state * md, const unsigned char *buf)
+{
+    __u32 S[8], W[64], t0, t1;
+    __u32 t;
+    int i;
+
+    /* copy state into S */
+    for (i = 0; i < 8; i++) {
+        S[i] = md->sha256.state[i];
+    }
+
+    /* copy the state into 512-bits into W[0..15] */
+    for (i = 0; i < 16; i++) {
+        LOAD32H(W[i], buf + (4*i));
+    }
+
+    /* fill W[16..63] */
+    for (i = 16; i < 64; i++) {
+        W[i] = Gamma1(W[i - 2]) + W[i - 7] + Gamma0(W[i - 15]) + W[i - 16];
+    }
+
+    /* Compress */
+     for (i = 0; i < 64; ++i) {
+         RND(S[0],S[1],S[2],S[3],S[4],S[5],S[6],S[7],i);
+         t = S[7]; S[7] = S[6]; S[6] = S[5]; S[5] = S[4];
+         S[4] = S[3]; S[3] = S[2]; S[2] = S[1]; S[1] = S[0]; S[0] = t;
+     }
+
+    /* feedback */
+    for (i = 0; i < 8; i++) {
+        md->sha256.state[i] = md->sha256.state[i] + S[i];
+    }
+}
+
+static void sha256_init(struct hash_state * md)
+{
+    md->sha256.curlen = 0;
+    md->sha256.length = 0;
+    md->sha256.state[0] = 0x6A09E667UL;
+    md->sha256.state[1] = 0xBB67AE85UL;
+    md->sha256.state[2] = 0x3C6EF372UL;
+    md->sha256.state[3] = 0xA54FF53AUL;
+    md->sha256.state[4] = 0x510E527FUL;
+    md->sha256.state[5] = 0x9B05688CUL;
+    md->sha256.state[6] = 0x1F83D9ABUL;
+    md->sha256.state[7] = 0x5BE0CD19UL;
+}
+
+#define MIN(x, y) ( ((x)<(y))?(x):(y) )
+#define SHA256_BLOCKSIZE 64
+static void sha256_process(struct hash_state * md, const unsigned char *in, unsigned long inlen)
+{
+    unsigned long n;
+
+    while (inlen > 0) {
+	    if (md->sha256.curlen == 0 && inlen >= SHA256_BLOCKSIZE) {
+		    sha256_compress(md, in);
+		    md->sha256.length += SHA256_BLOCKSIZE * 8;
+		    in += SHA256_BLOCKSIZE;
+		    inlen -= SHA256_BLOCKSIZE;
+	    } else {
+		    n = MIN(inlen, (SHA256_BLOCKSIZE - md->sha256.curlen));
+		    memcpy(md->sha256.buf + md->sha256.curlen, in, (size_t)n);
+		    md->sha256.curlen += n;
+		    in += n;
+		    inlen -= n;
+		    if (md->sha256.curlen == SHA256_BLOCKSIZE) {
+			    sha256_compress(md, md->sha256.buf);
+			    md->sha256.length += 8*SHA256_BLOCKSIZE;
+			    md->sha256.curlen = 0;
+		    }
+	    }
+    }
+}
+
+static void sha256_done(struct hash_state * md, unsigned char *out)
+{
+    int i;
+
+    /* increase the length of the message */
+    md->sha256.length += md->sha256.curlen * 8;
+
+    /* append the '1' bit */
+    md->sha256.buf[md->sha256.curlen++] = (unsigned char)0x80;
+
+    /* if the length is currently above 56 bytes we append zeros
+     * then compress.  Then we can fall back to padding zeros and length
+     * encoding like normal.
+     */
+    if (md->sha256.curlen > 56) {
+        while (md->sha256.curlen < 64) {
+            md->sha256.buf[md->sha256.curlen++] = (unsigned char)0;
+        }
+        sha256_compress(md, md->sha256.buf);
+        md->sha256.curlen = 0;
+    }
+
+    /* pad upto 56 bytes of zeroes */
+    while (md->sha256.curlen < 56) {
+        md->sha256.buf[md->sha256.curlen++] = (unsigned char)0;
+    }
+
+    /* store length */
+    STORE64H(md->sha256.length, md->sha256.buf+56);
+    sha256_compress(md, md->sha256.buf);
+
+    /* copy output */
+    for (i = 0; i < 8; i++) {
+        STORE32H(md->sha256.state[i], out+(4*i));
+    }
+}
+
+void erofs_sha256(const unsigned char *in, unsigned long in_size,
+		  unsigned char out[32])
+{
+	struct hash_state md;
+
+	sha256_init(&md);
+	sha256_process(&md, in, in_size);
+	sha256_done(&md, out);
+}
+
+#ifdef UNITTEST
+static const struct {
+	char *msg;
+	unsigned char hash[32];
+} tests[] = {
+	{ "",
+	  { 0xe3, 0xb0, 0xc4, 0x42, 0x98, 0xfc, 0x1c, 0x14,
+	    0x9a, 0xfb, 0xf4, 0xc8, 0x99, 0x6f, 0xb9, 0x24,
+	    0x27, 0xae, 0x41, 0xe4, 0x64, 0x9b, 0x93, 0x4c,
+	    0xa4, 0x95, 0x99, 0x1b, 0x78, 0x52, 0xb8, 0x55 }
+	},
+	{ "abc",
+	  { 0xba, 0x78, 0x16, 0xbf, 0x8f, 0x01, 0xcf, 0xea,
+	    0x41, 0x41, 0x40, 0xde, 0x5d, 0xae, 0x22, 0x23,
+	    0xb0, 0x03, 0x61, 0xa3, 0x96, 0x17, 0x7a, 0x9c,
+	    0xb4, 0x10, 0xff, 0x61, 0xf2, 0x00, 0x15, 0xad }
+	},
+	{ "abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq",
+	  { 0x24, 0x8d, 0x6a, 0x61, 0xd2, 0x06, 0x38, 0xb8,
+	    0xe5, 0xc0, 0x26, 0x93, 0x0c, 0x3e, 0x60, 0x39,
+	    0xa3, 0x3c, 0xe4, 0x59, 0x64, 0xff, 0x21, 0x67,
+	    0xf6, 0xec, 0xed, 0xd4, 0x19, 0xdb, 0x06, 0xc1 }
+	},
+};
+
+int main(int argc, char **argv)
+{
+	int i;
+	int errors = 0;
+	unsigned char tmp[32];
+
+	for (i = 0; i < (int)(sizeof(tests) / sizeof(tests[0])); i++) {
+		unsigned char *msg = (unsigned char *) tests[i].msg;
+		int len = strlen(tests[i].msg);
+
+		ext2fs_sha256(msg, len, tmp);
+		printf("SHA256 test message %d: ", i);
+		if (memcmp(tmp, tests[i].hash, 32) != 0) {
+			printf("FAILED\n");
+			errors++;
+		} else
+			printf("OK\n");
+	}
+	return errors;
+}
+
+#endif /* UNITTEST */
-- 
2.24.4