crypto: arm/poly1305 - incorporate OpenSSL/CRYPTOGAMS NEON implementation

This is a straight import of the OpenSSL/CRYPTOGAMS Poly1305 implementation
for NEON authored by Andy Polyakov, and contributed by him to the OpenSSL
project. The file 'poly1305-armv4.pl' is taken straight from this upstream
GitHub repository [0] at commit ec55a08dc0244ce570c4fc7cade330c60798952f,
and already contains all the changes required to build it as part of a
Linux kernel module.

[0] https://github.com/dot-asm/cryptogams

Co-developed-by: Andy Polyakov <appro@cryptogams.org>
Signed-off-by: Andy Polyakov <appro@cryptogams.org>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

arch/arm/crypto/Kconfig

@@ -132,6 +132,11 @@ config CRYPTO_CHACHA20_NEON
 	select CRYPTO_SKCIPHER
 	select CRYPTO_ARCH_HAVE_LIB_CHACHA
 
+config CRYPTO_POLY1305_ARM
+	tristate "Accelerated scalar and SIMD Poly1305 hash implementations"
+	select CRYPTO_HASH
+	select CRYPTO_ARCH_HAVE_LIB_POLY1305
+
 config CRYPTO_NHPOLY1305_NEON
 	tristate "NEON accelerated NHPoly1305 hash function (for Adiantum)"
 	depends on KERNEL_MODE_NEON

arch/arm/crypto/Makefile

@@ -10,6 +10,7 @@ obj-$(CONFIG_CRYPTO_SHA1_ARM_NEON) += sha1-arm-neon.o
 obj-$(CONFIG_CRYPTO_SHA256_ARM) += sha256-arm.o
 obj-$(CONFIG_CRYPTO_SHA512_ARM) += sha512-arm.o
 obj-$(CONFIG_CRYPTO_CHACHA20_NEON) += chacha-neon.o
+obj-$(CONFIG_CRYPTO_POLY1305_ARM) += poly1305-arm.o
 obj-$(CONFIG_CRYPTO_NHPOLY1305_NEON) += nhpoly1305-neon.o
 
 obj-$(CONFIG_CRYPTO_AES_ARM_CE) += aes-arm-ce.o
@@ -35,12 +36,16 @@ crct10dif-arm-ce-y	:= crct10dif-ce-core.o crct10dif-ce-glue.o
 crc32-arm-ce-y:= crc32-ce-core.o crc32-ce-glue.o
 chacha-neon-y := chacha-scalar-core.o chacha-glue.o
 chacha-neon-$(CONFIG_KERNEL_MODE_NEON) += chacha-neon-core.o
+poly1305-arm-y := poly1305-core.o poly1305-glue.o
 nhpoly1305-neon-y := nh-neon-core.o nhpoly1305-neon-glue.o
 
 ifdef REGENERATE_ARM_CRYPTO
 quiet_cmd_perl = PERL    $@
       cmd_perl = $(PERL) $(<) > $(@)
 
+$(src)/poly1305-core.S_shipped: $(src)/poly1305-armv4.pl
+	$(call cmd,perl)
+
 $(src)/sha256-core.S_shipped: $(src)/sha256-armv4.pl
 	$(call cmd,perl)
 
@@ -48,4 +53,9 @@ $(src)/sha512-core.S_shipped: $(src)/sha512-armv4.pl
 	$(call cmd,perl)
 endif
 
-clean-files += sha256-core.S sha512-core.S
+clean-files += poly1305-core.S sha256-core.S sha512-core.S
+
+# massage the perlasm code a bit so we only get the NEON routine if we need it
+poly1305-aflags-$(CONFIG_CPU_V7) := -U__LINUX_ARM_ARCH__ -D__LINUX_ARM_ARCH__=5
+poly1305-aflags-$(CONFIG_KERNEL_MODE_NEON) := -U__LINUX_ARM_ARCH__ -D__LINUX_ARM_ARCH__=7
+AFLAGS_poly1305-core.o += $(poly1305-aflags-y)

arch/arm/crypto/poly1305-glue.c

@@ -0,0 +1,276 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * OpenSSL/Cryptogams accelerated Poly1305 transform for ARM
+ *
+ * Copyright (C) 2019 Linaro Ltd. <ard.biesheuvel@linaro.org>
+ */
+
+#include <asm/hwcap.h>
+#include <asm/neon.h>
+#include <asm/simd.h>
+#include <asm/unaligned.h>
+#include <crypto/algapi.h>
+#include <crypto/internal/hash.h>
+#include <crypto/internal/poly1305.h>
+#include <crypto/internal/simd.h>
+#include <linux/cpufeature.h>
+#include <linux/crypto.h>
+#include <linux/jump_label.h>
+#include <linux/module.h>
+
+void poly1305_init_arm(void *state, const u8 *key);
+void poly1305_blocks_arm(void *state, const u8 *src, u32 len, u32 hibit);
+void poly1305_emit_arm(void *state, __le32 *digest, const u32 *nonce);
+
+void __weak poly1305_blocks_neon(void *state, const u8 *src, u32 len, u32 hibit)
+{
+}
+
+static __ro_after_init DEFINE_STATIC_KEY_FALSE(have_neon);
+
+void poly1305_init_arch(struct poly1305_desc_ctx *dctx, const u8 *key)
+{
+	poly1305_init_arm(&dctx->h, key);
+	dctx->s[0] = get_unaligned_le32(key + 16);
+	dctx->s[1] = get_unaligned_le32(key + 20);
+	dctx->s[2] = get_unaligned_le32(key + 24);
+	dctx->s[3] = get_unaligned_le32(key + 28);
+	dctx->buflen = 0;
+}
+EXPORT_SYMBOL(poly1305_init_arch);
+
+static int arm_poly1305_init(struct shash_desc *desc)
+{
+	struct poly1305_desc_ctx *dctx = shash_desc_ctx(desc);
+
+	dctx->buflen = 0;
+	dctx->rset = 0;
+	dctx->sset = false;
+
+	return 0;
+}
+
+static void arm_poly1305_blocks(struct poly1305_desc_ctx *dctx, const u8 *src,
+				 u32 len, u32 hibit, bool do_neon)
+{
+	if (unlikely(!dctx->sset)) {
+		if (!dctx->rset) {
+			poly1305_init_arm(&dctx->h, src);
+			src += POLY1305_BLOCK_SIZE;
+			len -= POLY1305_BLOCK_SIZE;
+			dctx->rset = 1;
+		}
+		if (len >= POLY1305_BLOCK_SIZE) {
+			dctx->s[0] = get_unaligned_le32(src +  0);
+			dctx->s[1] = get_unaligned_le32(src +  4);
+			dctx->s[2] = get_unaligned_le32(src +  8);
+			dctx->s[3] = get_unaligned_le32(src + 12);
+			src += POLY1305_BLOCK_SIZE;
+			len -= POLY1305_BLOCK_SIZE;
+			dctx->sset = true;
+		}
+		if (len < POLY1305_BLOCK_SIZE)
+			return;
+	}
+
+	len &= ~(POLY1305_BLOCK_SIZE - 1);
+
+	if (static_branch_likely(&have_neon) && likely(do_neon))
+		poly1305_blocks_neon(&dctx->h, src, len, hibit);
+	else
+		poly1305_blocks_arm(&dctx->h, src, len, hibit);
+}
+
+static void arm_poly1305_do_update(struct poly1305_desc_ctx *dctx,
+				    const u8 *src, u32 len, bool do_neon)
+{
+	if (unlikely(dctx->buflen)) {
+		u32 bytes = min(len, POLY1305_BLOCK_SIZE - dctx->buflen);
+
+		memcpy(dctx->buf + dctx->buflen, src, bytes);
+		src += bytes;
+		len -= bytes;
+		dctx->buflen += bytes;
+
+		if (dctx->buflen == POLY1305_BLOCK_SIZE) {
+			arm_poly1305_blocks(dctx, dctx->buf,
+					    POLY1305_BLOCK_SIZE, 1, false);
+			dctx->buflen = 0;
+		}
+	}
+
+	if (likely(len >= POLY1305_BLOCK_SIZE)) {
+		arm_poly1305_blocks(dctx, src, len, 1, do_neon);
+		src += round_down(len, POLY1305_BLOCK_SIZE);
+		len %= POLY1305_BLOCK_SIZE;
+	}
+
+	if (unlikely(len)) {
+		dctx->buflen = len;
+		memcpy(dctx->buf, src, len);
+	}
+}
+
+static int arm_poly1305_update(struct shash_desc *desc,
+			       const u8 *src, unsigned int srclen)
+{
+	struct poly1305_desc_ctx *dctx = shash_desc_ctx(desc);
+
+	arm_poly1305_do_update(dctx, src, srclen, false);
+	return 0;
+}
+
+static int __maybe_unused arm_poly1305_update_neon(struct shash_desc *desc,
+						   const u8 *src,
+						   unsigned int srclen)
+{
+	struct poly1305_desc_ctx *dctx = shash_desc_ctx(desc);
+	bool do_neon = crypto_simd_usable() && srclen > 128;
+
+	if (static_branch_likely(&have_neon) && do_neon)
+		kernel_neon_begin();
+	arm_poly1305_do_update(dctx, src, srclen, do_neon);
+	if (static_branch_likely(&have_neon) && do_neon)
+		kernel_neon_end();
+	return 0;
+}
+
+void poly1305_update_arch(struct poly1305_desc_ctx *dctx, const u8 *src,
+			  unsigned int nbytes)
+{
+	bool do_neon = IS_ENABLED(CONFIG_KERNEL_MODE_NEON) &&
+		       crypto_simd_usable();
+
+	if (unlikely(dctx->buflen)) {
+		u32 bytes = min(nbytes, POLY1305_BLOCK_SIZE - dctx->buflen);
+
+		memcpy(dctx->buf + dctx->buflen, src, bytes);
+		src += bytes;
+		nbytes -= bytes;
+		dctx->buflen += bytes;
+
+		if (dctx->buflen == POLY1305_BLOCK_SIZE) {
+			poly1305_blocks_arm(&dctx->h, dctx->buf,
+					    POLY1305_BLOCK_SIZE, 1);
+			dctx->buflen = 0;
+		}
+	}
+
+	if (likely(nbytes >= POLY1305_BLOCK_SIZE)) {
+		unsigned int len = round_down(nbytes, POLY1305_BLOCK_SIZE);
+
+		if (static_branch_likely(&have_neon) && do_neon) {
+			kernel_neon_begin();
+			poly1305_blocks_neon(&dctx->h, src, len, 1);
+			kernel_neon_end();
+		} else {
+			poly1305_blocks_arm(&dctx->h, src, len, 1);
+		}
+		src += len;
+		nbytes %= POLY1305_BLOCK_SIZE;
+	}
+
+	if (unlikely(nbytes)) {
+		dctx->buflen = nbytes;
+		memcpy(dctx->buf, src, nbytes);
+	}
+}
+EXPORT_SYMBOL(poly1305_update_arch);
+
+void poly1305_final_arch(struct poly1305_desc_ctx *dctx, u8 *dst)
+{
+	__le32 digest[4];
+	u64 f = 0;
+
+	if (unlikely(dctx->buflen)) {
+		dctx->buf[dctx->buflen++] = 1;
+		memset(dctx->buf + dctx->buflen, 0,
+		       POLY1305_BLOCK_SIZE - dctx->buflen);
+		poly1305_blocks_arm(&dctx->h, dctx->buf, POLY1305_BLOCK_SIZE, 0);
+	}
+
+	poly1305_emit_arm(&dctx->h, digest, dctx->s);
+
+	/* mac = (h + s) % (2^128) */
+	f = (f >> 32) + le32_to_cpu(digest[0]);
+	put_unaligned_le32(f, dst);
+	f = (f >> 32) + le32_to_cpu(digest[1]);
+	put_unaligned_le32(f, dst + 4);
+	f = (f >> 32) + le32_to_cpu(digest[2]);
+	put_unaligned_le32(f, dst + 8);
+	f = (f >> 32) + le32_to_cpu(digest[3]);
+	put_unaligned_le32(f, dst + 12);
+
+	*dctx = (struct poly1305_desc_ctx){};
+}
+EXPORT_SYMBOL(poly1305_final_arch);
+
+static int arm_poly1305_final(struct shash_desc *desc, u8 *dst)
+{
+	struct poly1305_desc_ctx *dctx = shash_desc_ctx(desc);
+
+	if (unlikely(!dctx->sset))
+		return -ENOKEY;
+
+	poly1305_final_arch(dctx, dst);
+	return 0;
+}
+
+static struct shash_alg arm_poly1305_algs[] = {{
+	.init			= arm_poly1305_init,
+	.update			= arm_poly1305_update,
+	.final			= arm_poly1305_final,
+	.digestsize		= POLY1305_DIGEST_SIZE,
+	.descsize		= sizeof(struct poly1305_desc_ctx),
+
+	.base.cra_name		= "poly1305",
+	.base.cra_driver_name	= "poly1305-arm",
+	.base.cra_priority	= 150,
+	.base.cra_blocksize	= POLY1305_BLOCK_SIZE,
+	.base.cra_module	= THIS_MODULE,
+#ifdef CONFIG_KERNEL_MODE_NEON
+}, {
+	.init			= arm_poly1305_init,
+	.update			= arm_poly1305_update_neon,
+	.final			= arm_poly1305_final,
+	.digestsize		= POLY1305_DIGEST_SIZE,
+	.descsize		= sizeof(struct poly1305_desc_ctx),
+
+	.base.cra_name		= "poly1305",
+	.base.cra_driver_name	= "poly1305-neon",
+	.base.cra_priority	= 200,
+	.base.cra_blocksize	= POLY1305_BLOCK_SIZE,
+	.base.cra_module	= THIS_MODULE,
+#endif
+}};
+
+static int __init arm_poly1305_mod_init(void)
+{
+	if (IS_ENABLED(CONFIG_KERNEL_MODE_NEON) &&
+	    (elf_hwcap & HWCAP_NEON))
+		static_branch_enable(&have_neon);
+	else
+		/* register only the first entry */
+		return crypto_register_shash(&arm_poly1305_algs[0]);
+
+	return crypto_register_shashes(arm_poly1305_algs,
+				       ARRAY_SIZE(arm_poly1305_algs));
+}
+
+static void __exit arm_poly1305_mod_exit(void)
+{
+	if (!static_branch_likely(&have_neon)) {
+		crypto_unregister_shash(&arm_poly1305_algs[0]);
+		return;
+	}
+	crypto_unregister_shashes(arm_poly1305_algs,
+				  ARRAY_SIZE(arm_poly1305_algs));
+}
+
+module_init(arm_poly1305_mod_init);
+module_exit(arm_poly1305_mod_exit);
+
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS_CRYPTO("poly1305");
+MODULE_ALIAS_CRYPTO("poly1305-arm");
+MODULE_ALIAS_CRYPTO("poly1305-neon");

lib/crypto/Kconfig

@@ -40,7 +40,7 @@ config CRYPTO_LIB_DES
 config CRYPTO_LIB_POLY1305_RSIZE
 	int
 	default 4 if X86_64
-	default 9 if ARM64
+	default 9 if ARM || ARM64
 	default 1
 
 config CRYPTO_ARCH_HAVE_LIB_POLY1305