370 lines
9.8 KiB
C
370 lines
9.8 KiB
C
// SPDX-License-Identifier: GPL-2.0 OR MIT
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/*
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* Copyright (C) 2015-2019 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
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*
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* This is an implementation of the ChaCha20Poly1305 AEAD construction.
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*
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* Information: https://tools.ietf.org/html/rfc8439
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*/
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#include <crypto/algapi.h>
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#include <crypto/chacha20poly1305.h>
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#include <crypto/chacha.h>
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#include <crypto/poly1305.h>
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#include <crypto/scatterwalk.h>
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#include <asm/unaligned.h>
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#include <linux/kernel.h>
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#include <linux/init.h>
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#include <linux/mm.h>
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#include <linux/module.h>
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#define CHACHA_KEY_WORDS (CHACHA_KEY_SIZE / sizeof(u32))
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bool __init chacha20poly1305_selftest(void);
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static void chacha_load_key(u32 *k, const u8 *in)
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{
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k[0] = get_unaligned_le32(in);
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k[1] = get_unaligned_le32(in + 4);
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k[2] = get_unaligned_le32(in + 8);
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k[3] = get_unaligned_le32(in + 12);
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k[4] = get_unaligned_le32(in + 16);
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k[5] = get_unaligned_le32(in + 20);
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k[6] = get_unaligned_le32(in + 24);
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k[7] = get_unaligned_le32(in + 28);
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}
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static void xchacha_init(u32 *chacha_state, const u8 *key, const u8 *nonce)
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{
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u32 k[CHACHA_KEY_WORDS];
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u8 iv[CHACHA_IV_SIZE];
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memset(iv, 0, 8);
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memcpy(iv + 8, nonce + 16, 8);
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chacha_load_key(k, key);
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/* Compute the subkey given the original key and first 128 nonce bits */
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chacha_init(chacha_state, k, nonce);
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hchacha_block(chacha_state, k, 20);
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chacha_init(chacha_state, k, iv);
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memzero_explicit(k, sizeof(k));
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memzero_explicit(iv, sizeof(iv));
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}
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static void
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__chacha20poly1305_encrypt(u8 *dst, const u8 *src, const size_t src_len,
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const u8 *ad, const size_t ad_len, u32 *chacha_state)
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{
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const u8 *pad0 = page_address(ZERO_PAGE(0));
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struct poly1305_desc_ctx poly1305_state;
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union {
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u8 block0[POLY1305_KEY_SIZE];
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__le64 lens[2];
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} b;
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chacha20_crypt(chacha_state, b.block0, pad0, sizeof(b.block0));
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poly1305_init(&poly1305_state, b.block0);
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poly1305_update(&poly1305_state, ad, ad_len);
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if (ad_len & 0xf)
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poly1305_update(&poly1305_state, pad0, 0x10 - (ad_len & 0xf));
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chacha20_crypt(chacha_state, dst, src, src_len);
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poly1305_update(&poly1305_state, dst, src_len);
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if (src_len & 0xf)
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poly1305_update(&poly1305_state, pad0, 0x10 - (src_len & 0xf));
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b.lens[0] = cpu_to_le64(ad_len);
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b.lens[1] = cpu_to_le64(src_len);
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poly1305_update(&poly1305_state, (u8 *)b.lens, sizeof(b.lens));
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poly1305_final(&poly1305_state, dst + src_len);
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memzero_explicit(chacha_state, CHACHA_STATE_WORDS * sizeof(u32));
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memzero_explicit(&b, sizeof(b));
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}
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void chacha20poly1305_encrypt(u8 *dst, const u8 *src, const size_t src_len,
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const u8 *ad, const size_t ad_len,
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const u64 nonce,
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const u8 key[CHACHA20POLY1305_KEY_SIZE])
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{
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u32 chacha_state[CHACHA_STATE_WORDS];
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u32 k[CHACHA_KEY_WORDS];
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__le64 iv[2];
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chacha_load_key(k, key);
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iv[0] = 0;
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iv[1] = cpu_to_le64(nonce);
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chacha_init(chacha_state, k, (u8 *)iv);
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__chacha20poly1305_encrypt(dst, src, src_len, ad, ad_len, chacha_state);
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memzero_explicit(iv, sizeof(iv));
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memzero_explicit(k, sizeof(k));
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}
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EXPORT_SYMBOL(chacha20poly1305_encrypt);
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void xchacha20poly1305_encrypt(u8 *dst, const u8 *src, const size_t src_len,
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const u8 *ad, const size_t ad_len,
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const u8 nonce[XCHACHA20POLY1305_NONCE_SIZE],
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const u8 key[CHACHA20POLY1305_KEY_SIZE])
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{
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u32 chacha_state[CHACHA_STATE_WORDS];
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xchacha_init(chacha_state, key, nonce);
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__chacha20poly1305_encrypt(dst, src, src_len, ad, ad_len, chacha_state);
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}
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EXPORT_SYMBOL(xchacha20poly1305_encrypt);
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static bool
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__chacha20poly1305_decrypt(u8 *dst, const u8 *src, const size_t src_len,
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const u8 *ad, const size_t ad_len, u32 *chacha_state)
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{
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const u8 *pad0 = page_address(ZERO_PAGE(0));
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struct poly1305_desc_ctx poly1305_state;
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size_t dst_len;
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int ret;
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union {
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u8 block0[POLY1305_KEY_SIZE];
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u8 mac[POLY1305_DIGEST_SIZE];
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__le64 lens[2];
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} b;
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if (unlikely(src_len < POLY1305_DIGEST_SIZE))
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return false;
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chacha20_crypt(chacha_state, b.block0, pad0, sizeof(b.block0));
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poly1305_init(&poly1305_state, b.block0);
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poly1305_update(&poly1305_state, ad, ad_len);
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if (ad_len & 0xf)
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poly1305_update(&poly1305_state, pad0, 0x10 - (ad_len & 0xf));
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dst_len = src_len - POLY1305_DIGEST_SIZE;
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poly1305_update(&poly1305_state, src, dst_len);
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if (dst_len & 0xf)
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poly1305_update(&poly1305_state, pad0, 0x10 - (dst_len & 0xf));
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b.lens[0] = cpu_to_le64(ad_len);
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b.lens[1] = cpu_to_le64(dst_len);
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poly1305_update(&poly1305_state, (u8 *)b.lens, sizeof(b.lens));
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poly1305_final(&poly1305_state, b.mac);
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ret = crypto_memneq(b.mac, src + dst_len, POLY1305_DIGEST_SIZE);
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if (likely(!ret))
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chacha20_crypt(chacha_state, dst, src, dst_len);
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memzero_explicit(&b, sizeof(b));
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return !ret;
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}
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bool chacha20poly1305_decrypt(u8 *dst, const u8 *src, const size_t src_len,
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const u8 *ad, const size_t ad_len,
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const u64 nonce,
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const u8 key[CHACHA20POLY1305_KEY_SIZE])
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{
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u32 chacha_state[CHACHA_STATE_WORDS];
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u32 k[CHACHA_KEY_WORDS];
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__le64 iv[2];
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bool ret;
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chacha_load_key(k, key);
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iv[0] = 0;
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iv[1] = cpu_to_le64(nonce);
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chacha_init(chacha_state, k, (u8 *)iv);
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ret = __chacha20poly1305_decrypt(dst, src, src_len, ad, ad_len,
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chacha_state);
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memzero_explicit(chacha_state, sizeof(chacha_state));
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memzero_explicit(iv, sizeof(iv));
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memzero_explicit(k, sizeof(k));
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return ret;
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}
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EXPORT_SYMBOL(chacha20poly1305_decrypt);
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bool xchacha20poly1305_decrypt(u8 *dst, const u8 *src, const size_t src_len,
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const u8 *ad, const size_t ad_len,
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const u8 nonce[XCHACHA20POLY1305_NONCE_SIZE],
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const u8 key[CHACHA20POLY1305_KEY_SIZE])
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{
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u32 chacha_state[CHACHA_STATE_WORDS];
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xchacha_init(chacha_state, key, nonce);
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return __chacha20poly1305_decrypt(dst, src, src_len, ad, ad_len,
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chacha_state);
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}
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EXPORT_SYMBOL(xchacha20poly1305_decrypt);
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static
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bool chacha20poly1305_crypt_sg_inplace(struct scatterlist *src,
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const size_t src_len,
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const u8 *ad, const size_t ad_len,
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const u64 nonce,
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const u8 key[CHACHA20POLY1305_KEY_SIZE],
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int encrypt)
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{
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const u8 *pad0 = page_address(ZERO_PAGE(0));
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struct poly1305_desc_ctx poly1305_state;
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u32 chacha_state[CHACHA_STATE_WORDS];
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struct sg_mapping_iter miter;
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size_t partial = 0;
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unsigned int flags;
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bool ret = true;
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int sl;
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union {
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struct {
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u32 k[CHACHA_KEY_WORDS];
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__le64 iv[2];
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};
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u8 block0[POLY1305_KEY_SIZE];
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u8 chacha_stream[CHACHA_BLOCK_SIZE];
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struct {
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u8 mac[2][POLY1305_DIGEST_SIZE];
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};
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__le64 lens[2];
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} b __aligned(16);
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chacha_load_key(b.k, key);
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b.iv[0] = 0;
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b.iv[1] = cpu_to_le64(nonce);
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chacha_init(chacha_state, b.k, (u8 *)b.iv);
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chacha20_crypt(chacha_state, b.block0, pad0, sizeof(b.block0));
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poly1305_init(&poly1305_state, b.block0);
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if (unlikely(ad_len)) {
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poly1305_update(&poly1305_state, ad, ad_len);
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if (ad_len & 0xf)
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poly1305_update(&poly1305_state, pad0, 0x10 - (ad_len & 0xf));
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}
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flags = SG_MITER_TO_SG;
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if (!preemptible())
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flags |= SG_MITER_ATOMIC;
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sg_miter_start(&miter, src, sg_nents(src), flags);
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for (sl = src_len; sl > 0 && sg_miter_next(&miter); sl -= miter.length) {
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u8 *addr = miter.addr;
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size_t length = min_t(size_t, sl, miter.length);
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if (!encrypt)
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poly1305_update(&poly1305_state, addr, length);
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if (unlikely(partial)) {
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size_t l = min(length, CHACHA_BLOCK_SIZE - partial);
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crypto_xor(addr, b.chacha_stream + partial, l);
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partial = (partial + l) & (CHACHA_BLOCK_SIZE - 1);
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addr += l;
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length -= l;
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}
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if (likely(length >= CHACHA_BLOCK_SIZE || length == sl)) {
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size_t l = length;
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if (unlikely(length < sl))
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l &= ~(CHACHA_BLOCK_SIZE - 1);
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chacha20_crypt(chacha_state, addr, addr, l);
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addr += l;
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length -= l;
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}
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if (unlikely(length > 0)) {
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chacha20_crypt(chacha_state, b.chacha_stream, pad0,
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CHACHA_BLOCK_SIZE);
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crypto_xor(addr, b.chacha_stream, length);
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partial = length;
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}
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if (encrypt)
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poly1305_update(&poly1305_state, miter.addr,
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min_t(size_t, sl, miter.length));
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}
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if (src_len & 0xf)
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poly1305_update(&poly1305_state, pad0, 0x10 - (src_len & 0xf));
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b.lens[0] = cpu_to_le64(ad_len);
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b.lens[1] = cpu_to_le64(src_len);
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poly1305_update(&poly1305_state, (u8 *)b.lens, sizeof(b.lens));
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if (likely(sl <= -POLY1305_DIGEST_SIZE)) {
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if (encrypt) {
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poly1305_final(&poly1305_state,
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miter.addr + miter.length + sl);
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ret = true;
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} else {
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poly1305_final(&poly1305_state, b.mac[0]);
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ret = !crypto_memneq(b.mac[0],
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miter.addr + miter.length + sl,
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POLY1305_DIGEST_SIZE);
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}
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}
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sg_miter_stop(&miter);
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if (unlikely(sl > -POLY1305_DIGEST_SIZE)) {
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poly1305_final(&poly1305_state, b.mac[1]);
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scatterwalk_map_and_copy(b.mac[encrypt], src, src_len,
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sizeof(b.mac[1]), encrypt);
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ret = encrypt ||
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!crypto_memneq(b.mac[0], b.mac[1], POLY1305_DIGEST_SIZE);
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}
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memzero_explicit(chacha_state, sizeof(chacha_state));
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memzero_explicit(&b, sizeof(b));
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return ret;
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}
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bool chacha20poly1305_encrypt_sg_inplace(struct scatterlist *src, size_t src_len,
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const u8 *ad, const size_t ad_len,
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const u64 nonce,
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const u8 key[CHACHA20POLY1305_KEY_SIZE])
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{
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return chacha20poly1305_crypt_sg_inplace(src, src_len, ad, ad_len,
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nonce, key, 1);
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}
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EXPORT_SYMBOL(chacha20poly1305_encrypt_sg_inplace);
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bool chacha20poly1305_decrypt_sg_inplace(struct scatterlist *src, size_t src_len,
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const u8 *ad, const size_t ad_len,
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const u64 nonce,
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const u8 key[CHACHA20POLY1305_KEY_SIZE])
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{
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if (unlikely(src_len < POLY1305_DIGEST_SIZE))
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return false;
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return chacha20poly1305_crypt_sg_inplace(src,
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src_len - POLY1305_DIGEST_SIZE,
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ad, ad_len, nonce, key, 0);
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}
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EXPORT_SYMBOL(chacha20poly1305_decrypt_sg_inplace);
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static int __init mod_init(void)
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{
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if (!IS_ENABLED(CONFIG_CRYPTO_MANAGER_DISABLE_TESTS) &&
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WARN_ON(!chacha20poly1305_selftest()))
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return -ENODEV;
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return 0;
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}
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module_init(mod_init);
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MODULE_LICENSE("GPL v2");
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MODULE_DESCRIPTION("ChaCha20Poly1305 AEAD construction");
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MODULE_AUTHOR("Jason A. Donenfeld <Jason@zx2c4.com>");
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