| Herbert Xu | cc868d8 | 2016-11-22 20:08:42 +0800 | [diff] [blame] | 1 | /* |
| 2 | * CBC: Cipher Block Chaining mode |
| 3 | * |
| 4 | * Copyright (c) 2016 Herbert Xu <herbert@gondor.apana.org.au> |
| 5 | * |
| 6 | * This program is free software; you can redistribute it and/or modify it |
| 7 | * under the terms of the GNU General Public License as published by the Free |
| 8 | * Software Foundation; either version 2 of the License, or (at your option) |
| 9 | * any later version. |
| 10 | * |
| 11 | */ |
| 12 | |
| 13 | #ifndef _CRYPTO_CBC_H |
| 14 | #define _CRYPTO_CBC_H |
| 15 | |
| 16 | #include <crypto/internal/skcipher.h> |
| 17 | #include <linux/string.h> |
| 18 | #include <linux/types.h> |
| 19 | |
| 20 | static inline int crypto_cbc_encrypt_segment( |
| 21 | struct skcipher_walk *walk, struct crypto_skcipher *tfm, |
| 22 | void (*fn)(struct crypto_skcipher *, const u8 *, u8 *)) |
| 23 | { |
| 24 | unsigned int bsize = crypto_skcipher_blocksize(tfm); |
| 25 | unsigned int nbytes = walk->nbytes; |
| 26 | u8 *src = walk->src.virt.addr; |
| 27 | u8 *dst = walk->dst.virt.addr; |
| 28 | u8 *iv = walk->iv; |
| 29 | |
| 30 | do { |
| 31 | crypto_xor(iv, src, bsize); |
| 32 | fn(tfm, iv, dst); |
| 33 | memcpy(iv, dst, bsize); |
| 34 | |
| 35 | src += bsize; |
| 36 | dst += bsize; |
| 37 | } while ((nbytes -= bsize) >= bsize); |
| 38 | |
| 39 | return nbytes; |
| 40 | } |
| 41 | |
| 42 | static inline int crypto_cbc_encrypt_inplace( |
| 43 | struct skcipher_walk *walk, struct crypto_skcipher *tfm, |
| 44 | void (*fn)(struct crypto_skcipher *, const u8 *, u8 *)) |
| 45 | { |
| 46 | unsigned int bsize = crypto_skcipher_blocksize(tfm); |
| 47 | unsigned int nbytes = walk->nbytes; |
| 48 | u8 *src = walk->src.virt.addr; |
| 49 | u8 *iv = walk->iv; |
| 50 | |
| 51 | do { |
| 52 | crypto_xor(src, iv, bsize); |
| 53 | fn(tfm, src, src); |
| 54 | iv = src; |
| 55 | |
| 56 | src += bsize; |
| 57 | } while ((nbytes -= bsize) >= bsize); |
| 58 | |
| 59 | memcpy(walk->iv, iv, bsize); |
| 60 | |
| 61 | return nbytes; |
| 62 | } |
| 63 | |
| 64 | static inline int crypto_cbc_encrypt_walk(struct skcipher_request *req, |
| 65 | void (*fn)(struct crypto_skcipher *, |
| 66 | const u8 *, u8 *)) |
| 67 | { |
| 68 | struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req); |
| 69 | struct skcipher_walk walk; |
| 70 | int err; |
| 71 | |
| 72 | err = skcipher_walk_virt(&walk, req, false); |
| 73 | |
| 74 | while (walk.nbytes) { |
| 75 | if (walk.src.virt.addr == walk.dst.virt.addr) |
| 76 | err = crypto_cbc_encrypt_inplace(&walk, tfm, fn); |
| 77 | else |
| 78 | err = crypto_cbc_encrypt_segment(&walk, tfm, fn); |
| 79 | err = skcipher_walk_done(&walk, err); |
| 80 | } |
| 81 | |
| 82 | return err; |
| 83 | } |
| 84 | |
| 85 | static inline int crypto_cbc_decrypt_segment( |
| 86 | struct skcipher_walk *walk, struct crypto_skcipher *tfm, |
| 87 | void (*fn)(struct crypto_skcipher *, const u8 *, u8 *)) |
| 88 | { |
| 89 | unsigned int bsize = crypto_skcipher_blocksize(tfm); |
| 90 | unsigned int nbytes = walk->nbytes; |
| 91 | u8 *src = walk->src.virt.addr; |
| 92 | u8 *dst = walk->dst.virt.addr; |
| 93 | u8 *iv = walk->iv; |
| 94 | |
| 95 | do { |
| 96 | fn(tfm, src, dst); |
| 97 | crypto_xor(dst, iv, bsize); |
| 98 | iv = src; |
| 99 | |
| 100 | src += bsize; |
| 101 | dst += bsize; |
| 102 | } while ((nbytes -= bsize) >= bsize); |
| 103 | |
| 104 | memcpy(walk->iv, iv, bsize); |
| 105 | |
| 106 | return nbytes; |
| 107 | } |
| 108 | |
| 109 | static inline int crypto_cbc_decrypt_inplace( |
| 110 | struct skcipher_walk *walk, struct crypto_skcipher *tfm, |
| 111 | void (*fn)(struct crypto_skcipher *, const u8 *, u8 *)) |
| 112 | { |
| 113 | unsigned int bsize = crypto_skcipher_blocksize(tfm); |
| 114 | unsigned int nbytes = walk->nbytes; |
| 115 | u8 *src = walk->src.virt.addr; |
| 116 | u8 last_iv[bsize]; |
| 117 | |
| 118 | /* Start of the last block. */ |
| 119 | src += nbytes - (nbytes & (bsize - 1)) - bsize; |
| 120 | memcpy(last_iv, src, bsize); |
| 121 | |
| 122 | for (;;) { |
| 123 | fn(tfm, src, src); |
| 124 | if ((nbytes -= bsize) < bsize) |
| 125 | break; |
| 126 | crypto_xor(src, src - bsize, bsize); |
| 127 | src -= bsize; |
| 128 | } |
| 129 | |
| 130 | crypto_xor(src, walk->iv, bsize); |
| 131 | memcpy(walk->iv, last_iv, bsize); |
| 132 | |
| 133 | return nbytes; |
| 134 | } |
| 135 | |
| 136 | static inline int crypto_cbc_decrypt_blocks( |
| 137 | struct skcipher_walk *walk, struct crypto_skcipher *tfm, |
| 138 | void (*fn)(struct crypto_skcipher *, const u8 *, u8 *)) |
| 139 | { |
| 140 | if (walk->src.virt.addr == walk->dst.virt.addr) |
| 141 | return crypto_cbc_decrypt_inplace(walk, tfm, fn); |
| 142 | else |
| 143 | return crypto_cbc_decrypt_segment(walk, tfm, fn); |
| 144 | } |
| 145 | |
| 146 | #endif /* _CRYPTO_CBC_H */ |