crypto: move gf128mul library into lib/crypto

The gf128mul library does not depend on the crypto API at all, so it can
be moved into lib/crypto. This will allow us to use it in other library
code in a subsequent patch without having to depend on CONFIG_CRYPTO.

While at it, change the Kconfig symbol name to align with other crypto
library implementations. However, the source file name is retained, as
it is reflected in the module .ko filename, and changing this might
break things for users.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

3 files changed, 421 insertions, 0 deletions

diff --git a/lib/crypto/Kconfig b/lib/crypto/Kconfig
index 7e9683e9f5c6..6767d86959de 100644
--- a/lib/crypto/Kconfig
+++ b/lib/crypto/Kconfig
@@ -11,6 +11,9 @@ config CRYPTO_LIB_AES
 config CRYPTO_LIB_ARC4
 	tristate
 
+config CRYPTO_LIB_GF128MUL
+	tristate
+
 config CRYPTO_ARCH_HAVE_LIB_BLAKE2S
 	bool
 	help
diff --git a/lib/crypto/Makefile b/lib/crypto/Makefile
index c852f067ab06..7000eeb72286 100644
--- a/lib/crypto/Makefile
+++ b/lib/crypto/Makefile
@@ -13,6 +13,8 @@ libaes-y					:= aes.o
 obj-$(CONFIG_CRYPTO_LIB_ARC4)			+= libarc4.o
 libarc4-y					:= arc4.o
 
+obj-$(CONFIG_CRYPTO_LIB_GF128MUL)		+= gf128mul.o
+
 # blake2s is used by the /dev/random driver which is always builtin
 obj-y						+= libblake2s.o
 libblake2s-y					:= blake2s.o
diff --git a/lib/crypto/gf128mul.c b/lib/crypto/gf128mul.c
new file mode 100644
index 000000000000..a69ae3e6c16c
--- /dev/null
+++ b/lib/crypto/gf128mul.c
@@ -0,0 +1,416 @@
+/* gf128mul.c - GF(2^128) multiplication functions
+ *
+ * Copyright (c) 2003, Dr Brian Gladman, Worcester, UK.
+ * Copyright (c) 2006, Rik Snel <rsnel@cube.dyndns.org>
+ *
+ * Based on Dr Brian Gladman's (GPL'd) work published at
+ * http://gladman.plushost.co.uk/oldsite/cryptography_technology/index.php
+ * See the original copyright notice below.
+ *
+ * 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.
+ */
+
+/*
+ ---------------------------------------------------------------------------
+ Copyright (c) 2003, Dr Brian Gladman, Worcester, UK.   All rights reserved.
+
+ LICENSE TERMS
+
+ The free distribution and use of this software in both source and binary
+ form is allowed (with or without changes) provided that:
+
+   1. distributions of this source code include the above copyright
+      notice, this list of conditions and the following disclaimer;
+
+   2. distributions in binary form include the above copyright
+      notice, this list of conditions and the following disclaimer
+      in the documentation and/or other associated materials;
+
+   3. the copyright holder's name is not used to endorse products
+      built using this software without specific written permission.
+
+ ALTERNATIVELY, provided that this notice is retained in full, this product
+ may be distributed under the terms of the GNU General Public License (GPL),
+ in which case the provisions of the GPL apply INSTEAD OF those given above.
+
+ DISCLAIMER
+
+ This software is provided 'as is' with no explicit or implied warranties
+ in respect of its properties, including, but not limited to, correctness
+ and/or fitness for purpose.
+ ---------------------------------------------------------------------------
+ Issue 31/01/2006
+
+ This file provides fast multiplication in GF(2^128) as required by several
+ cryptographic authentication modes
+*/
+
+#include <crypto/gf128mul.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+
+#define gf128mul_dat(q) { \
+	q(0x00), q(0x01), q(0x02), q(0x03), q(0x04), q(0x05), q(0x06), q(0x07),\
+	q(0x08), q(0x09), q(0x0a), q(0x0b), q(0x0c), q(0x0d), q(0x0e), q(0x0f),\
+	q(0x10), q(0x11), q(0x12), q(0x13), q(0x14), q(0x15), q(0x16), q(0x17),\
+	q(0x18), q(0x19), q(0x1a), q(0x1b), q(0x1c), q(0x1d), q(0x1e), q(0x1f),\
+	q(0x20), q(0x21), q(0x22), q(0x23), q(0x24), q(0x25), q(0x26), q(0x27),\
+	q(0x28), q(0x29), q(0x2a), q(0x2b), q(0x2c), q(0x2d), q(0x2e), q(0x2f),\
+	q(0x30), q(0x31), q(0x32), q(0x33), q(0x34), q(0x35), q(0x36), q(0x37),\
+	q(0x38), q(0x39), q(0x3a), q(0x3b), q(0x3c), q(0x3d), q(0x3e), q(0x3f),\
+	q(0x40), q(0x41), q(0x42), q(0x43), q(0x44), q(0x45), q(0x46), q(0x47),\
+	q(0x48), q(0x49), q(0x4a), q(0x4b), q(0x4c), q(0x4d), q(0x4e), q(0x4f),\
+	q(0x50), q(0x51), q(0x52), q(0x53), q(0x54), q(0x55), q(0x56), q(0x57),\
+	q(0x58), q(0x59), q(0x5a), q(0x5b), q(0x5c), q(0x5d), q(0x5e), q(0x5f),\
+	q(0x60), q(0x61), q(0x62), q(0x63), q(0x64), q(0x65), q(0x66), q(0x67),\
+	q(0x68), q(0x69), q(0x6a), q(0x6b), q(0x6c), q(0x6d), q(0x6e), q(0x6f),\
+	q(0x70), q(0x71), q(0x72), q(0x73), q(0x74), q(0x75), q(0x76), q(0x77),\
+	q(0x78), q(0x79), q(0x7a), q(0x7b), q(0x7c), q(0x7d), q(0x7e), q(0x7f),\
+	q(0x80), q(0x81), q(0x82), q(0x83), q(0x84), q(0x85), q(0x86), q(0x87),\
+	q(0x88), q(0x89), q(0x8a), q(0x8b), q(0x8c), q(0x8d), q(0x8e), q(0x8f),\
+	q(0x90), q(0x91), q(0x92), q(0x93), q(0x94), q(0x95), q(0x96), q(0x97),\
+	q(0x98), q(0x99), q(0x9a), q(0x9b), q(0x9c), q(0x9d), q(0x9e), q(0x9f),\
+	q(0xa0), q(0xa1), q(0xa2), q(0xa3), q(0xa4), q(0xa5), q(0xa6), q(0xa7),\
+	q(0xa8), q(0xa9), q(0xaa), q(0xab), q(0xac), q(0xad), q(0xae), q(0xaf),\
+	q(0xb0), q(0xb1), q(0xb2), q(0xb3), q(0xb4), q(0xb5), q(0xb6), q(0xb7),\
+	q(0xb8), q(0xb9), q(0xba), q(0xbb), q(0xbc), q(0xbd), q(0xbe), q(0xbf),\
+	q(0xc0), q(0xc1), q(0xc2), q(0xc3), q(0xc4), q(0xc5), q(0xc6), q(0xc7),\
+	q(0xc8), q(0xc9), q(0xca), q(0xcb), q(0xcc), q(0xcd), q(0xce), q(0xcf),\
+	q(0xd0), q(0xd1), q(0xd2), q(0xd3), q(0xd4), q(0xd5), q(0xd6), q(0xd7),\
+	q(0xd8), q(0xd9), q(0xda), q(0xdb), q(0xdc), q(0xdd), q(0xde), q(0xdf),\
+	q(0xe0), q(0xe1), q(0xe2), q(0xe3), q(0xe4), q(0xe5), q(0xe6), q(0xe7),\
+	q(0xe8), q(0xe9), q(0xea), q(0xeb), q(0xec), q(0xed), q(0xee), q(0xef),\
+	q(0xf0), q(0xf1), q(0xf2), q(0xf3), q(0xf4), q(0xf5), q(0xf6), q(0xf7),\
+	q(0xf8), q(0xf9), q(0xfa), q(0xfb), q(0xfc), q(0xfd), q(0xfe), q(0xff) \
+}
+
+/*
+ * Given a value i in 0..255 as the byte overflow when a field element
+ * in GF(2^128) is multiplied by x^8, the following macro returns the
+ * 16-bit value that must be XOR-ed into the low-degree end of the
+ * product to reduce it modulo the polynomial x^128 + x^7 + x^2 + x + 1.
+ *
+ * There are two versions of the macro, and hence two tables: one for
+ * the "be" convention where the highest-order bit is the coefficient of
+ * the highest-degree polynomial term, and one for the "le" convention
+ * where the highest-order bit is the coefficient of the lowest-degree
+ * polynomial term.  In both cases the values are stored in CPU byte
+ * endianness such that the coefficients are ordered consistently across
+ * bytes, i.e. in the "be" table bits 15..0 of the stored value
+ * correspond to the coefficients of x^15..x^0, and in the "le" table
+ * bits 15..0 correspond to the coefficients of x^0..x^15.
+ *
+ * Therefore, provided that the appropriate byte endianness conversions
+ * are done by the multiplication functions (and these must be in place
+ * anyway to support both little endian and big endian CPUs), the "be"
+ * table can be used for multiplications of both "bbe" and "ble"
+ * elements, and the "le" table can be used for multiplications of both
+ * "lle" and "lbe" elements.
+ */
+
+#define xda_be(i) ( \
+	(i & 0x80 ? 0x4380 : 0) ^ (i & 0x40 ? 0x21c0 : 0) ^ \
+	(i & 0x20 ? 0x10e0 : 0) ^ (i & 0x10 ? 0x0870 : 0) ^ \
+	(i & 0x08 ? 0x0438 : 0) ^ (i & 0x04 ? 0x021c : 0) ^ \
+	(i & 0x02 ? 0x010e : 0) ^ (i & 0x01 ? 0x0087 : 0) \
+)
+
+#define xda_le(i) ( \
+	(i & 0x80 ? 0xe100 : 0) ^ (i & 0x40 ? 0x7080 : 0) ^ \
+	(i & 0x20 ? 0x3840 : 0) ^ (i & 0x10 ? 0x1c20 : 0) ^ \
+	(i & 0x08 ? 0x0e10 : 0) ^ (i & 0x04 ? 0x0708 : 0) ^ \
+	(i & 0x02 ? 0x0384 : 0) ^ (i & 0x01 ? 0x01c2 : 0) \
+)
+
+static const u16 gf128mul_table_le[256] = gf128mul_dat(xda_le);
+static const u16 gf128mul_table_be[256] = gf128mul_dat(xda_be);
+
+/*
+ * The following functions multiply a field element by x^8 in
+ * the polynomial field representation.  They use 64-bit word operations
+ * to gain speed but compensate for machine endianness and hence work
+ * correctly on both styles of machine.
+ */
+
+static void gf128mul_x8_lle(be128 *x)
+{
+	u64 a = be64_to_cpu(x->a);
+	u64 b = be64_to_cpu(x->b);
+	u64 _tt = gf128mul_table_le[b & 0xff];
+
+	x->b = cpu_to_be64((b >> 8) | (a << 56));
+	x->a = cpu_to_be64((a >> 8) ^ (_tt << 48));
+}
+
+static void gf128mul_x8_bbe(be128 *x)
+{
+	u64 a = be64_to_cpu(x->a);
+	u64 b = be64_to_cpu(x->b);
+	u64 _tt = gf128mul_table_be[a >> 56];
+
+	x->a = cpu_to_be64((a << 8) | (b >> 56));
+	x->b = cpu_to_be64((b << 8) ^ _tt);
+}
+
+void gf128mul_x8_ble(le128 *r, const le128 *x)
+{
+	u64 a = le64_to_cpu(x->a);
+	u64 b = le64_to_cpu(x->b);
+	u64 _tt = gf128mul_table_be[a >> 56];
+
+	r->a = cpu_to_le64((a << 8) | (b >> 56));
+	r->b = cpu_to_le64((b << 8) ^ _tt);
+}
+EXPORT_SYMBOL(gf128mul_x8_ble);
+
+void gf128mul_lle(be128 *r, const be128 *b)
+{
+	be128 p[8];
+	int i;
+
+	p[0] = *r;
+	for (i = 0; i < 7; ++i)
+		gf128mul_x_lle(&p[i + 1], &p[i]);
+
+	memset(r, 0, sizeof(*r));
+	for (i = 0;;) {
+		u8 ch = ((u8 *)b)[15 - i];
+
+		if (ch & 0x80)
+			be128_xor(r, r, &p[0]);
+		if (ch & 0x40)
+			be128_xor(r, r, &p[1]);
+		if (ch & 0x20)
+			be128_xor(r, r, &p[2]);
+		if (ch & 0x10)
+			be128_xor(r, r, &p[3]);
+		if (ch & 0x08)
+			be128_xor(r, r, &p[4]);
+		if (ch & 0x04)
+			be128_xor(r, r, &p[5]);
+		if (ch & 0x02)
+			be128_xor(r, r, &p[6]);
+		if (ch & 0x01)
+			be128_xor(r, r, &p[7]);
+
+		if (++i >= 16)
+			break;
+
+		gf128mul_x8_lle(r);
+	}
+}
+EXPORT_SYMBOL(gf128mul_lle);
+
+void gf128mul_bbe(be128 *r, const be128 *b)
+{
+	be128 p[8];
+	int i;
+
+	p[0] = *r;
+	for (i = 0; i < 7; ++i)
+		gf128mul_x_bbe(&p[i + 1], &p[i]);
+
+	memset(r, 0, sizeof(*r));
+	for (i = 0;;) {
+		u8 ch = ((u8 *)b)[i];
+
+		if (ch & 0x80)
+			be128_xor(r, r, &p[7]);
+		if (ch & 0x40)
+			be128_xor(r, r, &p[6]);
+		if (ch & 0x20)
+			be128_xor(r, r, &p[5]);
+		if (ch & 0x10)
+			be128_xor(r, r, &p[4]);
+		if (ch & 0x08)
+			be128_xor(r, r, &p[3]);
+		if (ch & 0x04)
+			be128_xor(r, r, &p[2]);
+		if (ch & 0x02)
+			be128_xor(r, r, &p[1]);
+		if (ch & 0x01)
+			be128_xor(r, r, &p[0]);
+
+		if (++i >= 16)
+			break;
+
+		gf128mul_x8_bbe(r);
+	}
+}
+EXPORT_SYMBOL(gf128mul_bbe);
+
+/*      This version uses 64k bytes of table space.
+    A 16 byte buffer has to be multiplied by a 16 byte key
+    value in GF(2^128).  If we consider a GF(2^128) value in
+    the buffer's lowest byte, we can construct a table of
+    the 256 16 byte values that result from the 256 values
+    of this byte.  This requires 4096 bytes. But we also
+    need tables for each of the 16 higher bytes in the
+    buffer as well, which makes 64 kbytes in total.
+*/
+/* additional explanation
+ * t[0][BYTE] contains g*BYTE
+ * t[1][BYTE] contains g*x^8*BYTE
+ *  ..
+ * t[15][BYTE] contains g*x^120*BYTE */
+struct gf128mul_64k *gf128mul_init_64k_bbe(const be128 *g)
+{
+	struct gf128mul_64k *t;
+	int i, j, k;
+
+	t = kzalloc(sizeof(*t), GFP_KERNEL);
+	if (!t)
+		goto out;
+
+	for (i = 0; i < 16; i++) {
+		t->t[i] = kzalloc(sizeof(*t->t[i]), GFP_KERNEL);
+		if (!t->t[i]) {
+			gf128mul_free_64k(t);
+			t = NULL;
+			goto out;
+		}
+	}
+
+	t->t[0]->t[1] = *g;
+	for (j = 1; j <= 64; j <<= 1)
+		gf128mul_x_bbe(&t->t[0]->t[j + j], &t->t[0]->t[j]);
+
+	for (i = 0;;) {
+		for (j = 2; j < 256; j += j)
+			for (k = 1; k < j; ++k)
+				be128_xor(&t->t[i]->t[j + k],
+					  &t->t[i]->t[j], &t->t[i]->t[k]);
+
+		if (++i >= 16)
+			break;
+
+		for (j = 128; j > 0; j >>= 1) {
+			t->t[i]->t[j] = t->t[i - 1]->t[j];
+			gf128mul_x8_bbe(&t->t[i]->t[j]);
+		}
+	}
+
+out:
+	return t;
+}
+EXPORT_SYMBOL(gf128mul_init_64k_bbe);
+
+void gf128mul_free_64k(struct gf128mul_64k *t)
+{
+	int i;
+
+	for (i = 0; i < 16; i++)
+		kfree_sensitive(t->t[i]);
+	kfree_sensitive(t);
+}
+EXPORT_SYMBOL(gf128mul_free_64k);
+
+void gf128mul_64k_bbe(be128 *a, const struct gf128mul_64k *t)
+{
+	u8 *ap = (u8 *)a;
+	be128 r[1];
+	int i;
+
+	*r = t->t[0]->t[ap[15]];
+	for (i = 1; i < 16; ++i)
+		be128_xor(r, r, &t->t[i]->t[ap[15 - i]]);
+	*a = *r;
+}
+EXPORT_SYMBOL(gf128mul_64k_bbe);
+
+/*      This version uses 4k bytes of table space.
+    A 16 byte buffer has to be multiplied by a 16 byte key
+    value in GF(2^128).  If we consider a GF(2^128) value in a
+    single byte, we can construct a table of the 256 16 byte
+    values that result from the 256 values of this byte.
+    This requires 4096 bytes. If we take the highest byte in
+    the buffer and use this table to get the result, we then
+    have to multiply by x^120 to get the final value. For the
+    next highest byte the result has to be multiplied by x^112
+    and so on. But we can do this by accumulating the result
+    in an accumulator starting with the result for the top
+    byte.  We repeatedly multiply the accumulator value by
+    x^8 and then add in (i.e. xor) the 16 bytes of the next
+    lower byte in the buffer, stopping when we reach the
+    lowest byte. This requires a 4096 byte table.
+*/
+struct gf128mul_4k *gf128mul_init_4k_lle(const be128 *g)
+{
+	struct gf128mul_4k *t;
+	int j, k;
+
+	t = kzalloc(sizeof(*t), GFP_KERNEL);
+	if (!t)
+		goto out;
+
+	t->t[128] = *g;
+	for (j = 64; j > 0; j >>= 1)
+		gf128mul_x_lle(&t->t[j], &t->t[j+j]);
+
+	for (j = 2; j < 256; j += j)
+		for (k = 1; k < j; ++k)
+			be128_xor(&t->t[j + k], &t->t[j], &t->t[k]);
+
+out:
+	return t;
+}
+EXPORT_SYMBOL(gf128mul_init_4k_lle);
+
+struct gf128mul_4k *gf128mul_init_4k_bbe(const be128 *g)
+{
+	struct gf128mul_4k *t;
+	int j, k;
+
+	t = kzalloc(sizeof(*t), GFP_KERNEL);
+	if (!t)
+		goto out;
+
+	t->t[1] = *g;
+	for (j = 1; j <= 64; j <<= 1)
+		gf128mul_x_bbe(&t->t[j + j], &t->t[j]);
+
+	for (j = 2; j < 256; j += j)
+		for (k = 1; k < j; ++k)
+			be128_xor(&t->t[j + k], &t->t[j], &t->t[k]);
+
+out:
+	return t;
+}
+EXPORT_SYMBOL(gf128mul_init_4k_bbe);
+
+void gf128mul_4k_lle(be128 *a, const struct gf128mul_4k *t)
+{
+	u8 *ap = (u8 *)a;
+	be128 r[1];
+	int i = 15;
+
+	*r = t->t[ap[15]];
+	while (i--) {
+		gf128mul_x8_lle(r);
+		be128_xor(r, r, &t->t[ap[i]]);
+	}
+	*a = *r;
+}
+EXPORT_SYMBOL(gf128mul_4k_lle);
+
+void gf128mul_4k_bbe(be128 *a, const struct gf128mul_4k *t)
+{
+	u8 *ap = (u8 *)a;
+	be128 r[1];
+	int i = 0;
+
+	*r = t->t[ap[0]];
+	while (++i < 16) {
+		gf128mul_x8_bbe(r);
+		be128_xor(r, r, &t->t[ap[i]]);
+	}
+	*a = *r;
+}
+EXPORT_SYMBOL(gf128mul_4k_bbe);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Functions for multiplying elements of GF(2^128)");