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317 lines
7.6 KiB
317 lines
7.6 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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/* |
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* CMAC: Cipher Block Mode for Authentication |
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* |
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* Copyright © 2013 Jussi Kivilinna <[email protected]> |
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* |
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* Based on work by: |
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* Copyright © 2013 Tom St Denis <[email protected]> |
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* Based on crypto/xcbc.c: |
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* Copyright © 2006 USAGI/WIDE Project, |
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* Author: Kazunori Miyazawa <[email protected]> |
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*/ |
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#include <crypto/internal/cipher.h> |
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#include <crypto/internal/hash.h> |
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#include <linux/err.h> |
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#include <linux/kernel.h> |
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#include <linux/module.h> |
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/* |
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* +------------------------ |
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* | <parent tfm> |
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* +------------------------ |
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* | cmac_tfm_ctx |
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* +------------------------ |
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* | consts (block size * 2) |
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* +------------------------ |
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*/ |
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struct cmac_tfm_ctx { |
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struct crypto_cipher *child; |
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u8 ctx[]; |
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}; |
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/* |
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* +------------------------ |
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* | <shash desc> |
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* +------------------------ |
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* | cmac_desc_ctx |
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* +------------------------ |
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* | odds (block size) |
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* +------------------------ |
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* | prev (block size) |
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* +------------------------ |
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*/ |
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struct cmac_desc_ctx { |
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unsigned int len; |
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u8 ctx[]; |
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}; |
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static int crypto_cmac_digest_setkey(struct crypto_shash *parent, |
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const u8 *inkey, unsigned int keylen) |
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{ |
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unsigned long alignmask = crypto_shash_alignmask(parent); |
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struct cmac_tfm_ctx *ctx = crypto_shash_ctx(parent); |
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unsigned int bs = crypto_shash_blocksize(parent); |
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__be64 *consts = PTR_ALIGN((void *)ctx->ctx, |
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(alignmask | (__alignof__(__be64) - 1)) + 1); |
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u64 _const[2]; |
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int i, err = 0; |
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u8 msb_mask, gfmask; |
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err = crypto_cipher_setkey(ctx->child, inkey, keylen); |
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if (err) |
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return err; |
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/* encrypt the zero block */ |
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memset(consts, 0, bs); |
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crypto_cipher_encrypt_one(ctx->child, (u8 *)consts, (u8 *)consts); |
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switch (bs) { |
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case 16: |
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gfmask = 0x87; |
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_const[0] = be64_to_cpu(consts[1]); |
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_const[1] = be64_to_cpu(consts[0]); |
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/* gf(2^128) multiply zero-ciphertext with u and u^2 */ |
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for (i = 0; i < 4; i += 2) { |
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msb_mask = ((s64)_const[1] >> 63) & gfmask; |
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_const[1] = (_const[1] << 1) | (_const[0] >> 63); |
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_const[0] = (_const[0] << 1) ^ msb_mask; |
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consts[i + 0] = cpu_to_be64(_const[1]); |
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consts[i + 1] = cpu_to_be64(_const[0]); |
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} |
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break; |
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case 8: |
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gfmask = 0x1B; |
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_const[0] = be64_to_cpu(consts[0]); |
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/* gf(2^64) multiply zero-ciphertext with u and u^2 */ |
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for (i = 0; i < 2; i++) { |
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msb_mask = ((s64)_const[0] >> 63) & gfmask; |
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_const[0] = (_const[0] << 1) ^ msb_mask; |
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consts[i] = cpu_to_be64(_const[0]); |
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} |
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break; |
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} |
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return 0; |
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} |
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static int crypto_cmac_digest_init(struct shash_desc *pdesc) |
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{ |
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unsigned long alignmask = crypto_shash_alignmask(pdesc->tfm); |
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struct cmac_desc_ctx *ctx = shash_desc_ctx(pdesc); |
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int bs = crypto_shash_blocksize(pdesc->tfm); |
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u8 *prev = PTR_ALIGN((void *)ctx->ctx, alignmask + 1) + bs; |
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ctx->len = 0; |
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memset(prev, 0, bs); |
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return 0; |
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} |
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static int crypto_cmac_digest_update(struct shash_desc *pdesc, const u8 *p, |
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unsigned int len) |
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{ |
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struct crypto_shash *parent = pdesc->tfm; |
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unsigned long alignmask = crypto_shash_alignmask(parent); |
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struct cmac_tfm_ctx *tctx = crypto_shash_ctx(parent); |
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struct cmac_desc_ctx *ctx = shash_desc_ctx(pdesc); |
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struct crypto_cipher *tfm = tctx->child; |
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int bs = crypto_shash_blocksize(parent); |
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u8 *odds = PTR_ALIGN((void *)ctx->ctx, alignmask + 1); |
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u8 *prev = odds + bs; |
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/* checking the data can fill the block */ |
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if ((ctx->len + len) <= bs) { |
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memcpy(odds + ctx->len, p, len); |
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ctx->len += len; |
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return 0; |
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} |
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/* filling odds with new data and encrypting it */ |
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memcpy(odds + ctx->len, p, bs - ctx->len); |
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len -= bs - ctx->len; |
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p += bs - ctx->len; |
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crypto_xor(prev, odds, bs); |
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crypto_cipher_encrypt_one(tfm, prev, prev); |
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/* clearing the length */ |
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ctx->len = 0; |
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/* encrypting the rest of data */ |
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while (len > bs) { |
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crypto_xor(prev, p, bs); |
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crypto_cipher_encrypt_one(tfm, prev, prev); |
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p += bs; |
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len -= bs; |
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} |
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/* keeping the surplus of blocksize */ |
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if (len) { |
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memcpy(odds, p, len); |
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ctx->len = len; |
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} |
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return 0; |
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} |
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static int crypto_cmac_digest_final(struct shash_desc *pdesc, u8 *out) |
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{ |
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struct crypto_shash *parent = pdesc->tfm; |
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unsigned long alignmask = crypto_shash_alignmask(parent); |
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struct cmac_tfm_ctx *tctx = crypto_shash_ctx(parent); |
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struct cmac_desc_ctx *ctx = shash_desc_ctx(pdesc); |
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struct crypto_cipher *tfm = tctx->child; |
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int bs = crypto_shash_blocksize(parent); |
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u8 *consts = PTR_ALIGN((void *)tctx->ctx, |
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(alignmask | (__alignof__(__be64) - 1)) + 1); |
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u8 *odds = PTR_ALIGN((void *)ctx->ctx, alignmask + 1); |
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u8 *prev = odds + bs; |
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unsigned int offset = 0; |
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if (ctx->len != bs) { |
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unsigned int rlen; |
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u8 *p = odds + ctx->len; |
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*p = 0x80; |
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p++; |
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rlen = bs - ctx->len - 1; |
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if (rlen) |
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memset(p, 0, rlen); |
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offset += bs; |
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} |
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crypto_xor(prev, odds, bs); |
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crypto_xor(prev, consts + offset, bs); |
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crypto_cipher_encrypt_one(tfm, out, prev); |
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return 0; |
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} |
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static int cmac_init_tfm(struct crypto_tfm *tfm) |
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{ |
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struct crypto_cipher *cipher; |
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struct crypto_instance *inst = (void *)tfm->__crt_alg; |
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struct crypto_cipher_spawn *spawn = crypto_instance_ctx(inst); |
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struct cmac_tfm_ctx *ctx = crypto_tfm_ctx(tfm); |
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cipher = crypto_spawn_cipher(spawn); |
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if (IS_ERR(cipher)) |
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return PTR_ERR(cipher); |
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ctx->child = cipher; |
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return 0; |
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}; |
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static void cmac_exit_tfm(struct crypto_tfm *tfm) |
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{ |
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struct cmac_tfm_ctx *ctx = crypto_tfm_ctx(tfm); |
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crypto_free_cipher(ctx->child); |
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} |
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static int cmac_create(struct crypto_template *tmpl, struct rtattr **tb) |
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{ |
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struct shash_instance *inst; |
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struct crypto_cipher_spawn *spawn; |
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struct crypto_alg *alg; |
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unsigned long alignmask; |
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u32 mask; |
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int err; |
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err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SHASH, &mask); |
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if (err) |
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return err; |
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inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL); |
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if (!inst) |
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return -ENOMEM; |
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spawn = shash_instance_ctx(inst); |
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err = crypto_grab_cipher(spawn, shash_crypto_instance(inst), |
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crypto_attr_alg_name(tb[1]), 0, mask); |
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if (err) |
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goto err_free_inst; |
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alg = crypto_spawn_cipher_alg(spawn); |
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switch (alg->cra_blocksize) { |
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case 16: |
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case 8: |
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break; |
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default: |
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err = -EINVAL; |
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goto err_free_inst; |
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} |
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err = crypto_inst_setname(shash_crypto_instance(inst), tmpl->name, alg); |
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if (err) |
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goto err_free_inst; |
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alignmask = alg->cra_alignmask; |
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inst->alg.base.cra_alignmask = alignmask; |
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inst->alg.base.cra_priority = alg->cra_priority; |
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inst->alg.base.cra_blocksize = alg->cra_blocksize; |
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inst->alg.digestsize = alg->cra_blocksize; |
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inst->alg.descsize = |
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ALIGN(sizeof(struct cmac_desc_ctx), crypto_tfm_ctx_alignment()) |
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+ (alignmask & ~(crypto_tfm_ctx_alignment() - 1)) |
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+ alg->cra_blocksize * 2; |
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inst->alg.base.cra_ctxsize = |
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ALIGN(sizeof(struct cmac_tfm_ctx), crypto_tfm_ctx_alignment()) |
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+ ((alignmask | (__alignof__(__be64) - 1)) & |
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~(crypto_tfm_ctx_alignment() - 1)) |
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+ alg->cra_blocksize * 2; |
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inst->alg.base.cra_init = cmac_init_tfm; |
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inst->alg.base.cra_exit = cmac_exit_tfm; |
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inst->alg.init = crypto_cmac_digest_init; |
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inst->alg.update = crypto_cmac_digest_update; |
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inst->alg.final = crypto_cmac_digest_final; |
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inst->alg.setkey = crypto_cmac_digest_setkey; |
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inst->free = shash_free_singlespawn_instance; |
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err = shash_register_instance(tmpl, inst); |
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if (err) { |
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err_free_inst: |
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shash_free_singlespawn_instance(inst); |
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} |
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return err; |
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} |
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static struct crypto_template crypto_cmac_tmpl = { |
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.name = "cmac", |
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.create = cmac_create, |
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.module = THIS_MODULE, |
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}; |
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static int __init crypto_cmac_module_init(void) |
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{ |
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return crypto_register_template(&crypto_cmac_tmpl); |
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} |
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static void __exit crypto_cmac_module_exit(void) |
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{ |
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crypto_unregister_template(&crypto_cmac_tmpl); |
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} |
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subsys_initcall(crypto_cmac_module_init); |
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module_exit(crypto_cmac_module_exit); |
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MODULE_LICENSE("GPL"); |
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MODULE_DESCRIPTION("CMAC keyed hash algorithm"); |
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MODULE_ALIAS_CRYPTO("cmac"); |
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MODULE_IMPORT_NS(CRYPTO_INTERNAL);
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