[PATCH 08/13] purgatory/sha256: Provide implementation of sha256 in purgaotory context

[Vivek Goyal <vgoyal@redhat.com>]

Next two patches provide code for purgatory. This is a code which does
not link against the kernel and runs stand alone. This code runs between
two kernels. One of the primary purpose of this code is to verify the
digest of newly loaded kernel and making sure it matches the digest
computed at kernel load time.

We use sha256 for calculating digest of kexec segmetns. Purgatory can't
use stanard crypto API as that API is not available in purgatory context.

Hence, I have copied code from crypto/sha256_generic.c and compiled it
with purgaotry code so that it could be used. I could not
#include sha256_generic.c file here as some of the function signature
requiered little tweaking. Original functions work with crypto API but
these ones don't

So instead of doing #include on sha256_generic.c I just copied relevant
portions of code into arch/x86/purgatory/sha256.c. Now we shouldn't have to
touch this code at all. Do let me know if there are better ways to handle it.

This patch does not enable compiling of this code. That happens in next
patch. I wanted to highlight this change in a separate patch for easy
review.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
---
 arch/x86/purgatory/sha256.c | 284 ++++++++++++++++++++++++++++++++++++++++++++
 arch/x86/purgatory/sha256.h |  22 ++++
 2 files changed, 306 insertions(+)
 create mode 100644 arch/x86/purgatory/sha256.c
 create mode 100644 arch/x86/purgatory/sha256.h

diff --git a/arch/x86/purgatory/sha256.c b/arch/x86/purgatory/sha256.c
new file mode 100644
index 0000000..1e814ca
--- /dev/null
+++ b/arch/x86/purgatory/sha256.c
@@ -0,0 +1,284 @@
+/*
+ * SHA-256, as specified in
+ * http://csrc.nist.gov/groups/STM/cavp/documents/shs/sha256-384-512.pdf
+ *
+ * SHA-256 code by Jean-Luc Cooke <jlcooke@certainkey.com>.
+ *
+ * Copyright (c) Jean-Luc Cooke <jlcooke@certainkey.com>
+ * Copyright (c) Andrew McDonald <andrew@mcdonald.org.uk>
+ * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
+ * Copyright (c) 2014 Red Hat Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ */
+
+#include <linux/bitops.h>
+#include <asm/byteorder.h>
+#include "sha256.h"
+#include "../boot/string.h"
+
+static inline u32 Ch(u32 x, u32 y, u32 z)
+{
+	return z ^ (x & (y ^ z));
+}
+
+static inline u32 Maj(u32 x, u32 y, u32 z)
+{
+	return (x & y) | (z & (x | y));
+}
+
+#define e0(x)       (ror32(x, 2) ^ ror32(x, 13) ^ ror32(x, 22))
+#define e1(x)       (ror32(x, 6) ^ ror32(x, 11) ^ ror32(x, 25))
+#define s0(x)       (ror32(x, 7) ^ ror32(x, 18) ^ (x >> 3))
+#define s1(x)       (ror32(x, 17) ^ ror32(x, 19) ^ (x >> 10))
+
+static inline void LOAD_OP(int I, u32 *W, const u8 *input)
+{
+	W[I] = __be32_to_cpu(((__be32 *)(input))[I]);
+}
+
+static inline void BLEND_OP(int I, u32 *W)
+{
+	W[I] = s1(W[I-2]) + W[I-7] + s0(W[I-15]) + W[I-16];
+}
+
+static void sha256_transform(u32 *state, const u8 *input)
+{
+	u32 a, b, c, d, e, f, g, h, t1, t2;
+	u32 W[64];
+	int i;
+
+	/* load the input */
+	for (i = 0; i < 16; i++)
+		LOAD_OP(i, W, input);
+
+	/* now blend */
+	for (i = 16; i < 64; i++)
+		BLEND_OP(i, W);
+
+	/* load the state into our registers */
+	a = state[0];  b = state[1];  c = state[2];  d = state[3];
+	e = state[4];  f = state[5];  g = state[6];  h = state[7];
+
+	/* now iterate */
+	t1 = h + e1(e) + Ch(e, f, g) + 0x428a2f98 + W[0];
+	t2 = e0(a) + Maj(a, b, c);    d += t1;    h = t1 + t2;
+	t1 = g + e1(d) + Ch(d, e, f) + 0x71374491 + W[1];
+	t2 = e0(h) + Maj(h, a, b);    c += t1;    g = t1 + t2;
+	t1 = f + e1(c) + Ch(c, d, e) + 0xb5c0fbcf + W[2];
+	t2 = e0(g) + Maj(g, h, a);    b += t1;    f = t1 + t2;
+	t1 = e + e1(b) + Ch(b, c, d) + 0xe9b5dba5 + W[3];
+	t2 = e0(f) + Maj(f, g, h);    a += t1;    e = t1 + t2;
+	t1 = d + e1(a) + Ch(a, b, c) + 0x3956c25b + W[4];
+	t2 = e0(e) + Maj(e, f, g);    h += t1;    d = t1 + t2;
+	t1 = c + e1(h) + Ch(h, a, b) + 0x59f111f1 + W[5];
+	t2 = e0(d) + Maj(d, e, f);    g += t1;    c = t1 + t2;
+	t1 = b + e1(g) + Ch(g, h, a) + 0x923f82a4 + W[6];
+	t2 = e0(c) + Maj(c, d, e);    f += t1;    b = t1 + t2;
+	t1 = a + e1(f) + Ch(f, g, h) + 0xab1c5ed5 + W[7];
+	t2 = e0(b) + Maj(b, c, d);    e += t1;    a = t1 + t2;
+
+	t1 = h + e1(e) + Ch(e, f, g) + 0xd807aa98 + W[8];
+	t2 = e0(a) + Maj(a, b, c);    d += t1;    h = t1 + t2;
+	t1 = g + e1(d) + Ch(d, e, f) + 0x12835b01 + W[9];
+	t2 = e0(h) + Maj(h, a, b);    c += t1;    g = t1 + t2;
+	t1 = f + e1(c) + Ch(c, d, e) + 0x243185be + W[10];
+	t2 = e0(g) + Maj(g, h, a);    b += t1;    f = t1 + t2;
+	t1 = e + e1(b) + Ch(b, c, d) + 0x550c7dc3 + W[11];
+	t2 = e0(f) + Maj(f, g, h);    a += t1;    e = t1 + t2;
+	t1 = d + e1(a) + Ch(a, b, c) + 0x72be5d74 + W[12];
+	t2 = e0(e) + Maj(e, f, g);    h += t1;    d = t1 + t2;
+	t1 = c + e1(h) + Ch(h, a, b) + 0x80deb1fe + W[13];
+	t2 = e0(d) + Maj(d, e, f);    g += t1;    c = t1 + t2;
+	t1 = b + e1(g) + Ch(g, h, a) + 0x9bdc06a7 + W[14];
+	t2 = e0(c) + Maj(c, d, e);    f += t1;    b = t1 + t2;
+	t1 = a + e1(f) + Ch(f, g, h) + 0xc19bf174 + W[15];
+	t2 = e0(b) + Maj(b, c, d);    e += t1;    a = t1+t2;
+
+	t1 = h + e1(e) + Ch(e, f, g) + 0xe49b69c1 + W[16];
+	t2 = e0(a) + Maj(a, b, c);    d += t1;    h = t1+t2;
+	t1 = g + e1(d) + Ch(d, e, f) + 0xefbe4786 + W[17];
+	t2 = e0(h) + Maj(h, a, b);    c += t1;    g = t1+t2;
+	t1 = f + e1(c) + Ch(c, d, e) + 0x0fc19dc6 + W[18];
+	t2 = e0(g) + Maj(g, h, a);    b += t1;    f = t1+t2;
+	t1 = e + e1(b) + Ch(b, c, d) + 0x240ca1cc + W[19];
+	t2 = e0(f) + Maj(f, g, h);    a += t1;    e = t1+t2;
+	t1 = d + e1(a) + Ch(a, b, c) + 0x2de92c6f + W[20];
+	t2 = e0(e) + Maj(e, f, g);    h += t1;    d = t1+t2;
+	t1 = c + e1(h) + Ch(h, a, b) + 0x4a7484aa + W[21];
+	t2 = e0(d) + Maj(d, e, f);    g += t1;    c = t1+t2;
+	t1 = b + e1(g) + Ch(g, h, a) + 0x5cb0a9dc + W[22];
+	t2 = e0(c) + Maj(c, d, e);    f += t1;    b = t1+t2;
+	t1 = a + e1(f) + Ch(f, g, h) + 0x76f988da + W[23];
+	t2 = e0(b) + Maj(b, c, d);    e += t1;    a = t1+t2;
+
+	t1 = h + e1(e) + Ch(e, f, g) + 0x983e5152 + W[24];
+	t2 = e0(a) + Maj(a, b, c);    d += t1;    h = t1+t2;
+	t1 = g + e1(d) + Ch(d, e, f) + 0xa831c66d + W[25];
+	t2 = e0(h) + Maj(h, a, b);    c += t1;    g = t1+t2;
+	t1 = f + e1(c) + Ch(c, d, e) + 0xb00327c8 + W[26];
+	t2 = e0(g) + Maj(g, h, a);    b += t1;    f = t1+t2;
+	t1 = e + e1(b) + Ch(b, c, d) + 0xbf597fc7 + W[27];
+	t2 = e0(f) + Maj(f, g, h);    a += t1;    e = t1+t2;
+	t1 = d + e1(a) + Ch(a, b, c) + 0xc6e00bf3 + W[28];
+	t2 = e0(e) + Maj(e, f, g);    h += t1;    d = t1+t2;
+	t1 = c + e1(h) + Ch(h, a, b) + 0xd5a79147 + W[29];
+	t2 = e0(d) + Maj(d, e, f);    g += t1;    c = t1+t2;
+	t1 = b + e1(g) + Ch(g, h, a) + 0x06ca6351 + W[30];
+	t2 = e0(c) + Maj(c, d, e);    f += t1;    b = t1+t2;
+	t1 = a + e1(f) + Ch(f, g, h) + 0x14292967 + W[31];
+	t2 = e0(b) + Maj(b, c, d);    e += t1;    a = t1+t2;
+
+	t1 = h + e1(e) + Ch(e, f, g) + 0x27b70a85 + W[32];
+	t2 = e0(a) + Maj(a, b, c);    d += t1;    h = t1+t2;
+	t1 = g + e1(d) + Ch(d, e, f) + 0x2e1b2138 + W[33];
+	t2 = e0(h) + Maj(h, a, b);    c += t1;    g = t1+t2;
+	t1 = f + e1(c) + Ch(c, d, e) + 0x4d2c6dfc + W[34];
+	t2 = e0(g) + Maj(g, h, a);    b += t1;    f = t1+t2;
+	t1 = e + e1(b) + Ch(b, c, d) + 0x53380d13 + W[35];
+	t2 = e0(f) + Maj(f, g, h);    a += t1;    e = t1+t2;
+	t1 = d + e1(a) + Ch(a, b, c) + 0x650a7354 + W[36];
+	t2 = e0(e) + Maj(e, f, g);    h += t1;    d = t1+t2;
+	t1 = c + e1(h) + Ch(h, a, b) + 0x766a0abb + W[37];
+	t2 = e0(d) + Maj(d, e, f);    g += t1;    c = t1+t2;
+	t1 = b + e1(g) + Ch(g, h, a) + 0x81c2c92e + W[38];
+	t2 = e0(c) + Maj(c, d, e);    f += t1;    b = t1+t2;
+	t1 = a + e1(f) + Ch(f, g, h) + 0x92722c85 + W[39];
+	t2 = e0(b) + Maj(b, c, d);    e += t1;    a = t1+t2;
+
+	t1 = h + e1(e) + Ch(e, f, g) + 0xa2bfe8a1 + W[40];
+	t2 = e0(a) + Maj(a, b, c);    d += t1;    h = t1+t2;
+	t1 = g + e1(d) + Ch(d, e, f) + 0xa81a664b + W[41];
+	t2 = e0(h) + Maj(h, a, b);    c += t1;    g = t1+t2;
+	t1 = f + e1(c) + Ch(c, d, e) + 0xc24b8b70 + W[42];
+	t2 = e0(g) + Maj(g, h, a);    b += t1;    f = t1+t2;
+	t1 = e + e1(b) + Ch(b, c, d) + 0xc76c51a3 + W[43];
+	t2 = e0(f) + Maj(f, g, h);    a += t1;    e = t1+t2;
+	t1 = d + e1(a) + Ch(a, b, c) + 0xd192e819 + W[44];
+	t2 = e0(e) + Maj(e, f, g);    h += t1;    d = t1+t2;
+	t1 = c + e1(h) + Ch(h, a, b) + 0xd6990624 + W[45];
+	t2 = e0(d) + Maj(d, e, f);    g += t1;    c = t1+t2;
+	t1 = b + e1(g) + Ch(g, h, a) + 0xf40e3585 + W[46];
+	t2 = e0(c) + Maj(c, d, e);    f += t1;    b = t1+t2;
+	t1 = a + e1(f) + Ch(f, g, h) + 0x106aa070 + W[47];
+	t2 = e0(b) + Maj(b, c, d);    e += t1;    a = t1+t2;
+
+	t1 = h + e1(e) + Ch(e, f, g) + 0x19a4c116 + W[48];
+	t2 = e0(a) + Maj(a, b, c);    d += t1;    h = t1+t2;
+	t1 = g + e1(d) + Ch(d, e, f) + 0x1e376c08 + W[49];
+	t2 = e0(h) + Maj(h, a, b);    c += t1;    g = t1+t2;
+	t1 = f + e1(c) + Ch(c, d, e) + 0x2748774c + W[50];
+	t2 = e0(g) + Maj(g, h, a);    b += t1;    f = t1+t2;
+	t1 = e + e1(b) + Ch(b, c, d) + 0x34b0bcb5 + W[51];
+	t2 = e0(f) + Maj(f, g, h);    a += t1;    e = t1+t2;
+	t1 = d + e1(a) + Ch(a, b, c) + 0x391c0cb3 + W[52];
+	t2 = e0(e) + Maj(e, f, g);    h += t1;    d = t1+t2;
+	t1 = c + e1(h) + Ch(h, a, b) + 0x4ed8aa4a + W[53];
+	t2 = e0(d) + Maj(d, e, f);    g += t1;    c = t1+t2;
+	t1 = b + e1(g) + Ch(g, h, a) + 0x5b9cca4f + W[54];
+	t2 = e0(c) + Maj(c, d, e);    f += t1;    b = t1+t2;
+	t1 = a + e1(f) + Ch(f, g, h) + 0x682e6ff3 + W[55];
+	t2 = e0(b) + Maj(b, c, d);    e += t1;    a = t1+t2;
+
+	t1 = h + e1(e) + Ch(e, f, g) + 0x748f82ee + W[56];
+	t2 = e0(a) + Maj(a, b, c);    d += t1;    h = t1+t2;
+	t1 = g + e1(d) + Ch(d, e, f) + 0x78a5636f + W[57];
+	t2 = e0(h) + Maj(h, a, b);    c += t1;    g = t1+t2;
+	t1 = f + e1(c) + Ch(c, d, e) + 0x84c87814 + W[58];
+	t2 = e0(g) + Maj(g, h, a);    b += t1;    f = t1+t2;
+	t1 = e + e1(b) + Ch(b, c, d) + 0x8cc70208 + W[59];
+	t2 = e0(f) + Maj(f, g, h);    a += t1;    e = t1+t2;
+	t1 = d + e1(a) + Ch(a, b, c) + 0x90befffa + W[60];
+	t2 = e0(e) + Maj(e, f, g);    h += t1;    d = t1+t2;
+	t1 = c + e1(h) + Ch(h, a, b) + 0xa4506ceb + W[61];
+	t2 = e0(d) + Maj(d, e, f);    g += t1;    c = t1+t2;
+	t1 = b + e1(g) + Ch(g, h, a) + 0xbef9a3f7 + W[62];
+	t2 = e0(c) + Maj(c, d, e);    f += t1;    b = t1+t2;
+	t1 = a + e1(f) + Ch(f, g, h) + 0xc67178f2 + W[63];
+	t2 = e0(b) + Maj(b, c, d);    e += t1;    a = t1+t2;
+
+	state[0] += a; state[1] += b; state[2] += c; state[3] += d;
+	state[4] += e; state[5] += f; state[6] += g; state[7] += h;
+
+	/* clear any sensitive info... */
+	a = b = c = d = e = f = g = h = t1 = t2 = 0;
+	memset(W, 0, 64 * sizeof(u32));
+}
+
+int sha256_init(struct sha256_state *sctx)
+{
+	sctx->state[0] = SHA256_H0;
+	sctx->state[1] = SHA256_H1;
+	sctx->state[2] = SHA256_H2;
+	sctx->state[3] = SHA256_H3;
+	sctx->state[4] = SHA256_H4;
+	sctx->state[5] = SHA256_H5;
+	sctx->state[6] = SHA256_H6;
+	sctx->state[7] = SHA256_H7;
+	sctx->count = 0;
+
+	return 0;
+}
+
+int sha256_update(struct sha256_state *sctx, const u8 *data,
+					unsigned int len)
+{
+	unsigned int partial, done;
+	const u8 *src;
+
+	partial = sctx->count & 0x3f;
+	sctx->count += len;
+	done = 0;
+	src = data;
+
+	if ((partial + len) > 63) {
+		if (partial) {
+			done = -partial;
+			memcpy(sctx->buf + partial, data, done + 64);
+			src = sctx->buf;
+		}
+
+		do {
+			sha256_transform(sctx->state, src);
+			done += 64;
+			src = data + done;
+		} while (done + 63 < len);
+
+		partial = 0;
+	}
+	memcpy(sctx->buf + partial, src, len - done);
+
+	return 0;
+}
+
+int sha256_final(struct sha256_state *sctx, u8 *out)
+{
+	__be32 *dst = (__be32 *)out;
+	__be64 bits;
+	unsigned int index, pad_len;
+	int i;
+	static const u8 padding[64] = { 0x80, };
+
+	/* Save number of bits */
+	bits = cpu_to_be64(sctx->count << 3);
+
+	/* Pad out to 56 mod 64. */
+	index = sctx->count & 0x3f;
+	pad_len = (index < 56) ? (56 - index) : ((64+56) - index);
+	sha256_update(sctx, padding, pad_len);
+
+	/* Append length (before padding) */
+	sha256_update(sctx, (const u8 *)&bits, sizeof(bits));
+
+	/* Store state in digest */
+	for (i = 0; i < 8; i++)
+		dst[i] = cpu_to_be32(sctx->state[i]);
+
+	/* Zeroize sensitive information. */
+	memset(sctx, 0, sizeof(*sctx));
+
+	return 0;
+}
diff --git a/arch/x86/purgatory/sha256.h b/arch/x86/purgatory/sha256.h
new file mode 100644
index 0000000..bd15a41
--- /dev/null
+++ b/arch/x86/purgatory/sha256.h
@@ -0,0 +1,22 @@
+/*
+ *  Copyright (C) 2014 Red Hat Inc.
+ *
+ *  Author: Vivek Goyal <vgoyal@redhat.com>
+ *
+ * This source code is licensed under the GNU General Public License,
+ * Version 2.  See the file COPYING for more details.
+ */
+
+#ifndef SHA256_H
+#define SHA256_H
+
+
+#include <linux/types.h>
+#include <crypto/sha.h>
+
+extern int sha256_init(struct sha256_state *sctx);
+extern int sha256_update(struct sha256_state *sctx, const u8 *input,
+				unsigned int length);
+extern int sha256_final(struct sha256_state *sctx, u8 *hash);
+
+#endif /* SHA256_H */
-- 
1.9.0