518 lines
12 KiB
C
518 lines
12 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Accelerated GHASH implementation with ARMv8 PMULL instructions.
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*
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* Copyright (C) 2014 - 2018 Linaro Ltd. <ard.biesheuvel@linaro.org>
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*/
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#include <asm/neon.h>
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#include <asm/simd.h>
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#include <asm/unaligned.h>
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#include <crypto/aes.h>
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#include <crypto/algapi.h>
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#include <crypto/b128ops.h>
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#include <crypto/gf128mul.h>
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#include <crypto/internal/aead.h>
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#include <crypto/internal/hash.h>
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#include <crypto/internal/simd.h>
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#include <crypto/internal/skcipher.h>
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#include <crypto/scatterwalk.h>
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#include <linux/cpufeature.h>
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#include <linux/crypto.h>
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#include <linux/module.h>
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MODULE_DESCRIPTION("GHASH and AES-GCM using ARMv8 Crypto Extensions");
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MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>");
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MODULE_LICENSE("GPL v2");
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MODULE_ALIAS_CRYPTO("ghash");
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#define GHASH_BLOCK_SIZE 16
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#define GHASH_DIGEST_SIZE 16
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#define GCM_IV_SIZE 12
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struct ghash_key {
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be128 k;
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u64 h[][2];
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};
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struct ghash_desc_ctx {
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u64 digest[GHASH_DIGEST_SIZE/sizeof(u64)];
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u8 buf[GHASH_BLOCK_SIZE];
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u32 count;
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};
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struct gcm_aes_ctx {
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struct crypto_aes_ctx aes_key;
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struct ghash_key ghash_key;
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};
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asmlinkage void pmull_ghash_update_p64(int blocks, u64 dg[], const char *src,
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u64 const h[][2], const char *head);
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asmlinkage void pmull_ghash_update_p8(int blocks, u64 dg[], const char *src,
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u64 const h[][2], const char *head);
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asmlinkage void pmull_gcm_encrypt(int bytes, u8 dst[], const u8 src[],
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u64 const h[][2], u64 dg[], u8 ctr[],
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u32 const rk[], int rounds, u8 tag[]);
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asmlinkage int pmull_gcm_decrypt(int bytes, u8 dst[], const u8 src[],
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u64 const h[][2], u64 dg[], u8 ctr[],
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u32 const rk[], int rounds, const u8 l[],
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const u8 tag[], u64 authsize);
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static int ghash_init(struct shash_desc *desc)
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{
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struct ghash_desc_ctx *ctx = shash_desc_ctx(desc);
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*ctx = (struct ghash_desc_ctx){};
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return 0;
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}
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static void ghash_do_update(int blocks, u64 dg[], const char *src,
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struct ghash_key *key, const char *head)
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{
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be128 dst = { cpu_to_be64(dg[1]), cpu_to_be64(dg[0]) };
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do {
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const u8 *in = src;
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if (head) {
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in = head;
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blocks++;
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head = NULL;
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} else {
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src += GHASH_BLOCK_SIZE;
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}
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crypto_xor((u8 *)&dst, in, GHASH_BLOCK_SIZE);
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gf128mul_lle(&dst, &key->k);
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} while (--blocks);
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dg[0] = be64_to_cpu(dst.b);
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dg[1] = be64_to_cpu(dst.a);
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}
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static __always_inline
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void ghash_do_simd_update(int blocks, u64 dg[], const char *src,
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struct ghash_key *key, const char *head,
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void (*simd_update)(int blocks, u64 dg[],
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const char *src,
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u64 const h[][2],
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const char *head))
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{
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if (likely(crypto_simd_usable())) {
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kernel_neon_begin();
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simd_update(blocks, dg, src, key->h, head);
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kernel_neon_end();
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} else {
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ghash_do_update(blocks, dg, src, key, head);
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}
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}
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/* avoid hogging the CPU for too long */
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#define MAX_BLOCKS (SZ_64K / GHASH_BLOCK_SIZE)
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static int ghash_update(struct shash_desc *desc, const u8 *src,
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unsigned int len)
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{
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struct ghash_desc_ctx *ctx = shash_desc_ctx(desc);
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unsigned int partial = ctx->count % GHASH_BLOCK_SIZE;
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ctx->count += len;
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if ((partial + len) >= GHASH_BLOCK_SIZE) {
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struct ghash_key *key = crypto_shash_ctx(desc->tfm);
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int blocks;
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if (partial) {
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int p = GHASH_BLOCK_SIZE - partial;
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memcpy(ctx->buf + partial, src, p);
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src += p;
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len -= p;
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}
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blocks = len / GHASH_BLOCK_SIZE;
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len %= GHASH_BLOCK_SIZE;
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do {
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int chunk = min(blocks, MAX_BLOCKS);
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ghash_do_simd_update(chunk, ctx->digest, src, key,
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partial ? ctx->buf : NULL,
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pmull_ghash_update_p8);
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blocks -= chunk;
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src += chunk * GHASH_BLOCK_SIZE;
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partial = 0;
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} while (unlikely(blocks > 0));
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}
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if (len)
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memcpy(ctx->buf + partial, src, len);
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return 0;
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}
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static int ghash_final(struct shash_desc *desc, u8 *dst)
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{
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struct ghash_desc_ctx *ctx = shash_desc_ctx(desc);
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unsigned int partial = ctx->count % GHASH_BLOCK_SIZE;
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if (partial) {
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struct ghash_key *key = crypto_shash_ctx(desc->tfm);
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memset(ctx->buf + partial, 0, GHASH_BLOCK_SIZE - partial);
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ghash_do_simd_update(1, ctx->digest, ctx->buf, key, NULL,
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pmull_ghash_update_p8);
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}
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put_unaligned_be64(ctx->digest[1], dst);
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put_unaligned_be64(ctx->digest[0], dst + 8);
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memzero_explicit(ctx, sizeof(*ctx));
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return 0;
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}
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static void ghash_reflect(u64 h[], const be128 *k)
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{
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u64 carry = be64_to_cpu(k->a) & BIT(63) ? 1 : 0;
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h[0] = (be64_to_cpu(k->b) << 1) | carry;
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h[1] = (be64_to_cpu(k->a) << 1) | (be64_to_cpu(k->b) >> 63);
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if (carry)
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h[1] ^= 0xc200000000000000UL;
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}
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static int ghash_setkey(struct crypto_shash *tfm,
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const u8 *inkey, unsigned int keylen)
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{
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struct ghash_key *key = crypto_shash_ctx(tfm);
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if (keylen != GHASH_BLOCK_SIZE)
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return -EINVAL;
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/* needed for the fallback */
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memcpy(&key->k, inkey, GHASH_BLOCK_SIZE);
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ghash_reflect(key->h[0], &key->k);
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return 0;
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}
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static struct shash_alg ghash_alg = {
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.base.cra_name = "ghash",
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.base.cra_driver_name = "ghash-neon",
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.base.cra_priority = 150,
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.base.cra_blocksize = GHASH_BLOCK_SIZE,
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.base.cra_ctxsize = sizeof(struct ghash_key) + sizeof(u64[2]),
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.base.cra_module = THIS_MODULE,
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.digestsize = GHASH_DIGEST_SIZE,
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.init = ghash_init,
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.update = ghash_update,
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.final = ghash_final,
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.setkey = ghash_setkey,
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.descsize = sizeof(struct ghash_desc_ctx),
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};
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static int num_rounds(struct crypto_aes_ctx *ctx)
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{
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/*
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* # of rounds specified by AES:
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* 128 bit key 10 rounds
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* 192 bit key 12 rounds
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* 256 bit key 14 rounds
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* => n byte key => 6 + (n/4) rounds
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*/
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return 6 + ctx->key_length / 4;
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}
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static int gcm_setkey(struct crypto_aead *tfm, const u8 *inkey,
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unsigned int keylen)
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{
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struct gcm_aes_ctx *ctx = crypto_aead_ctx(tfm);
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u8 key[GHASH_BLOCK_SIZE];
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be128 h;
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int ret;
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ret = aes_expandkey(&ctx->aes_key, inkey, keylen);
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if (ret)
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return -EINVAL;
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aes_encrypt(&ctx->aes_key, key, (u8[AES_BLOCK_SIZE]){});
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/* needed for the fallback */
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memcpy(&ctx->ghash_key.k, key, GHASH_BLOCK_SIZE);
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ghash_reflect(ctx->ghash_key.h[0], &ctx->ghash_key.k);
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h = ctx->ghash_key.k;
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gf128mul_lle(&h, &ctx->ghash_key.k);
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ghash_reflect(ctx->ghash_key.h[1], &h);
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gf128mul_lle(&h, &ctx->ghash_key.k);
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ghash_reflect(ctx->ghash_key.h[2], &h);
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gf128mul_lle(&h, &ctx->ghash_key.k);
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ghash_reflect(ctx->ghash_key.h[3], &h);
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return 0;
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}
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static int gcm_setauthsize(struct crypto_aead *tfm, unsigned int authsize)
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{
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switch (authsize) {
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case 4:
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case 8:
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case 12 ... 16:
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break;
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default:
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return -EINVAL;
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}
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return 0;
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}
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static void gcm_update_mac(u64 dg[], const u8 *src, int count, u8 buf[],
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int *buf_count, struct gcm_aes_ctx *ctx)
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{
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if (*buf_count > 0) {
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int buf_added = min(count, GHASH_BLOCK_SIZE - *buf_count);
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memcpy(&buf[*buf_count], src, buf_added);
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*buf_count += buf_added;
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src += buf_added;
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count -= buf_added;
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}
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if (count >= GHASH_BLOCK_SIZE || *buf_count == GHASH_BLOCK_SIZE) {
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int blocks = count / GHASH_BLOCK_SIZE;
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ghash_do_simd_update(blocks, dg, src, &ctx->ghash_key,
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*buf_count ? buf : NULL,
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pmull_ghash_update_p64);
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src += blocks * GHASH_BLOCK_SIZE;
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count %= GHASH_BLOCK_SIZE;
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*buf_count = 0;
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}
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if (count > 0) {
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memcpy(buf, src, count);
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*buf_count = count;
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}
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}
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static void gcm_calculate_auth_mac(struct aead_request *req, u64 dg[])
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{
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struct crypto_aead *aead = crypto_aead_reqtfm(req);
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struct gcm_aes_ctx *ctx = crypto_aead_ctx(aead);
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u8 buf[GHASH_BLOCK_SIZE];
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struct scatter_walk walk;
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u32 len = req->assoclen;
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int buf_count = 0;
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scatterwalk_start(&walk, req->src);
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do {
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u32 n = scatterwalk_clamp(&walk, len);
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u8 *p;
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if (!n) {
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scatterwalk_start(&walk, sg_next(walk.sg));
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n = scatterwalk_clamp(&walk, len);
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}
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p = scatterwalk_map(&walk);
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gcm_update_mac(dg, p, n, buf, &buf_count, ctx);
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len -= n;
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scatterwalk_unmap(p);
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scatterwalk_advance(&walk, n);
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scatterwalk_done(&walk, 0, len);
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} while (len);
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if (buf_count) {
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memset(&buf[buf_count], 0, GHASH_BLOCK_SIZE - buf_count);
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ghash_do_simd_update(1, dg, buf, &ctx->ghash_key, NULL,
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pmull_ghash_update_p64);
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}
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}
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static int gcm_encrypt(struct aead_request *req)
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{
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struct crypto_aead *aead = crypto_aead_reqtfm(req);
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struct gcm_aes_ctx *ctx = crypto_aead_ctx(aead);
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int nrounds = num_rounds(&ctx->aes_key);
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struct skcipher_walk walk;
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u8 buf[AES_BLOCK_SIZE];
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u8 iv[AES_BLOCK_SIZE];
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u64 dg[2] = {};
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be128 lengths;
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u8 *tag;
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int err;
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lengths.a = cpu_to_be64(req->assoclen * 8);
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lengths.b = cpu_to_be64(req->cryptlen * 8);
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if (req->assoclen)
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gcm_calculate_auth_mac(req, dg);
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memcpy(iv, req->iv, GCM_IV_SIZE);
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put_unaligned_be32(2, iv + GCM_IV_SIZE);
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err = skcipher_walk_aead_encrypt(&walk, req, false);
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do {
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const u8 *src = walk.src.virt.addr;
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u8 *dst = walk.dst.virt.addr;
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int nbytes = walk.nbytes;
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tag = (u8 *)&lengths;
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if (unlikely(nbytes > 0 && nbytes < AES_BLOCK_SIZE)) {
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src = dst = memcpy(buf + sizeof(buf) - nbytes,
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src, nbytes);
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} else if (nbytes < walk.total) {
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nbytes &= ~(AES_BLOCK_SIZE - 1);
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tag = NULL;
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}
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kernel_neon_begin();
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pmull_gcm_encrypt(nbytes, dst, src, ctx->ghash_key.h,
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dg, iv, ctx->aes_key.key_enc, nrounds,
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tag);
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kernel_neon_end();
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if (unlikely(!nbytes))
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break;
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if (unlikely(nbytes > 0 && nbytes < AES_BLOCK_SIZE))
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memcpy(walk.dst.virt.addr,
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buf + sizeof(buf) - nbytes, nbytes);
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err = skcipher_walk_done(&walk, walk.nbytes - nbytes);
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} while (walk.nbytes);
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if (err)
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return err;
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/* copy authtag to end of dst */
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scatterwalk_map_and_copy(tag, req->dst, req->assoclen + req->cryptlen,
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crypto_aead_authsize(aead), 1);
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return 0;
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}
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static int gcm_decrypt(struct aead_request *req)
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{
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struct crypto_aead *aead = crypto_aead_reqtfm(req);
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struct gcm_aes_ctx *ctx = crypto_aead_ctx(aead);
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unsigned int authsize = crypto_aead_authsize(aead);
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int nrounds = num_rounds(&ctx->aes_key);
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struct skcipher_walk walk;
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u8 otag[AES_BLOCK_SIZE];
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u8 buf[AES_BLOCK_SIZE];
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u8 iv[AES_BLOCK_SIZE];
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u64 dg[2] = {};
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be128 lengths;
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u8 *tag;
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int ret;
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int err;
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lengths.a = cpu_to_be64(req->assoclen * 8);
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lengths.b = cpu_to_be64((req->cryptlen - authsize) * 8);
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if (req->assoclen)
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gcm_calculate_auth_mac(req, dg);
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memcpy(iv, req->iv, GCM_IV_SIZE);
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put_unaligned_be32(2, iv + GCM_IV_SIZE);
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scatterwalk_map_and_copy(otag, req->src,
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req->assoclen + req->cryptlen - authsize,
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authsize, 0);
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err = skcipher_walk_aead_decrypt(&walk, req, false);
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do {
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const u8 *src = walk.src.virt.addr;
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u8 *dst = walk.dst.virt.addr;
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int nbytes = walk.nbytes;
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tag = (u8 *)&lengths;
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if (unlikely(nbytes > 0 && nbytes < AES_BLOCK_SIZE)) {
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src = dst = memcpy(buf + sizeof(buf) - nbytes,
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src, nbytes);
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} else if (nbytes < walk.total) {
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nbytes &= ~(AES_BLOCK_SIZE - 1);
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tag = NULL;
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}
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kernel_neon_begin();
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ret = pmull_gcm_decrypt(nbytes, dst, src, ctx->ghash_key.h,
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dg, iv, ctx->aes_key.key_enc,
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nrounds, tag, otag, authsize);
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kernel_neon_end();
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if (unlikely(!nbytes))
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break;
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if (unlikely(nbytes > 0 && nbytes < AES_BLOCK_SIZE))
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memcpy(walk.dst.virt.addr,
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buf + sizeof(buf) - nbytes, nbytes);
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err = skcipher_walk_done(&walk, walk.nbytes - nbytes);
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} while (walk.nbytes);
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if (err)
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return err;
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return ret ? -EBADMSG : 0;
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}
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static struct aead_alg gcm_aes_alg = {
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.ivsize = GCM_IV_SIZE,
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.chunksize = AES_BLOCK_SIZE,
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.maxauthsize = AES_BLOCK_SIZE,
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.setkey = gcm_setkey,
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.setauthsize = gcm_setauthsize,
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.encrypt = gcm_encrypt,
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.decrypt = gcm_decrypt,
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.base.cra_name = "gcm(aes)",
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.base.cra_driver_name = "gcm-aes-ce",
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.base.cra_priority = 300,
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.base.cra_blocksize = 1,
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.base.cra_ctxsize = sizeof(struct gcm_aes_ctx) +
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4 * sizeof(u64[2]),
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.base.cra_module = THIS_MODULE,
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};
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static int __init ghash_ce_mod_init(void)
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{
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if (!cpu_have_named_feature(ASIMD))
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return -ENODEV;
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if (cpu_have_named_feature(PMULL))
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return crypto_register_aead(&gcm_aes_alg);
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return crypto_register_shash(&ghash_alg);
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}
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static void __exit ghash_ce_mod_exit(void)
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{
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if (cpu_have_named_feature(PMULL))
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crypto_unregister_aead(&gcm_aes_alg);
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else
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crypto_unregister_shash(&ghash_alg);
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}
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static const struct cpu_feature ghash_cpu_feature[] = {
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{ cpu_feature(PMULL) }, { }
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};
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MODULE_DEVICE_TABLE(cpu, ghash_cpu_feature);
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module_init(ghash_ce_mod_init);
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module_exit(ghash_ce_mod_exit);
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