342 lines
8.5 KiB
C
342 lines
8.5 KiB
C
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/*
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* Cryptographic API.
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*
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* Cipher operations.
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*
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* Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the Free
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* Software Foundation; either version 2 of the License, or (at your option)
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* any later version.
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*
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*/
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#include <linux/compiler.h>
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#include <linux/kernel.h>
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#include <linux/crypto.h>
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#include <linux/errno.h>
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#include <linux/mm.h>
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#include <linux/slab.h>
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#include <linux/string.h>
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#include <asm/scatterlist.h>
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#include "internal.h"
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#include "scatterwalk.h"
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typedef void (cryptfn_t)(void *, u8 *, const u8 *);
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typedef void (procfn_t)(struct crypto_tfm *, u8 *,
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u8*, cryptfn_t, void *);
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static inline void xor_64(u8 *a, const u8 *b)
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{
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((u32 *)a)[0] ^= ((u32 *)b)[0];
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((u32 *)a)[1] ^= ((u32 *)b)[1];
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}
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static inline void xor_128(u8 *a, const u8 *b)
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{
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((u32 *)a)[0] ^= ((u32 *)b)[0];
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((u32 *)a)[1] ^= ((u32 *)b)[1];
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((u32 *)a)[2] ^= ((u32 *)b)[2];
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((u32 *)a)[3] ^= ((u32 *)b)[3];
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}
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static inline void *prepare_src(struct scatter_walk *walk, int bsize,
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void *tmp, int in_place)
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{
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void *src = walk->data;
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int n = bsize;
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if (unlikely(scatterwalk_across_pages(walk, bsize))) {
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src = tmp;
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n = scatterwalk_copychunks(src, walk, bsize, 0);
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}
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scatterwalk_advance(walk, n);
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return src;
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}
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static inline void *prepare_dst(struct scatter_walk *walk, int bsize,
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void *tmp, int in_place)
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{
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void *dst = walk->data;
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if (unlikely(scatterwalk_across_pages(walk, bsize)) || in_place)
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dst = tmp;
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return dst;
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}
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static inline void complete_src(struct scatter_walk *walk, int bsize,
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void *src, int in_place)
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{
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}
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static inline void complete_dst(struct scatter_walk *walk, int bsize,
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void *dst, int in_place)
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{
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int n = bsize;
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if (unlikely(scatterwalk_across_pages(walk, bsize)))
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n = scatterwalk_copychunks(dst, walk, bsize, 1);
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else if (in_place)
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memcpy(walk->data, dst, bsize);
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scatterwalk_advance(walk, n);
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}
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/*
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* Generic encrypt/decrypt wrapper for ciphers, handles operations across
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* multiple page boundaries by using temporary blocks. In user context,
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* the kernel is given a chance to schedule us once per block.
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*/
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static int crypt(struct crypto_tfm *tfm,
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struct scatterlist *dst,
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struct scatterlist *src,
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unsigned int nbytes, cryptfn_t crfn,
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procfn_t prfn, void *info)
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{
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struct scatter_walk walk_in, walk_out;
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const unsigned int bsize = crypto_tfm_alg_blocksize(tfm);
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u8 tmp_src[bsize];
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u8 tmp_dst[bsize];
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if (!nbytes)
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return 0;
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if (nbytes % bsize) {
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tfm->crt_flags |= CRYPTO_TFM_RES_BAD_BLOCK_LEN;
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return -EINVAL;
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}
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scatterwalk_start(&walk_in, src);
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scatterwalk_start(&walk_out, dst);
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for(;;) {
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u8 *src_p, *dst_p;
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int in_place;
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scatterwalk_map(&walk_in, 0);
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scatterwalk_map(&walk_out, 1);
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in_place = scatterwalk_samebuf(&walk_in, &walk_out);
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do {
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src_p = prepare_src(&walk_in, bsize, tmp_src,
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in_place);
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dst_p = prepare_dst(&walk_out, bsize, tmp_dst,
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in_place);
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prfn(tfm, dst_p, src_p, crfn, info);
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complete_src(&walk_in, bsize, src_p, in_place);
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complete_dst(&walk_out, bsize, dst_p, in_place);
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nbytes -= bsize;
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} while (nbytes &&
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!scatterwalk_across_pages(&walk_in, bsize) &&
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!scatterwalk_across_pages(&walk_out, bsize));
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scatterwalk_done(&walk_in, 0, nbytes);
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scatterwalk_done(&walk_out, 1, nbytes);
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if (!nbytes)
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return 0;
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crypto_yield(tfm);
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}
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}
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static void cbc_process_encrypt(struct crypto_tfm *tfm, u8 *dst, u8 *src,
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cryptfn_t fn, void *info)
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{
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u8 *iv = info;
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tfm->crt_u.cipher.cit_xor_block(iv, src);
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fn(crypto_tfm_ctx(tfm), dst, iv);
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memcpy(iv, dst, crypto_tfm_alg_blocksize(tfm));
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}
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static void cbc_process_decrypt(struct crypto_tfm *tfm, u8 *dst, u8 *src,
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cryptfn_t fn, void *info)
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{
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u8 *iv = info;
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fn(crypto_tfm_ctx(tfm), dst, src);
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tfm->crt_u.cipher.cit_xor_block(dst, iv);
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memcpy(iv, src, crypto_tfm_alg_blocksize(tfm));
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}
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static void ecb_process(struct crypto_tfm *tfm, u8 *dst, u8 *src,
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cryptfn_t fn, void *info)
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{
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fn(crypto_tfm_ctx(tfm), dst, src);
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}
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static int setkey(struct crypto_tfm *tfm, const u8 *key, unsigned int keylen)
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{
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struct cipher_alg *cia = &tfm->__crt_alg->cra_cipher;
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if (keylen < cia->cia_min_keysize || keylen > cia->cia_max_keysize) {
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tfm->crt_flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
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return -EINVAL;
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} else
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return cia->cia_setkey(crypto_tfm_ctx(tfm), key, keylen,
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&tfm->crt_flags);
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}
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static int ecb_encrypt(struct crypto_tfm *tfm,
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struct scatterlist *dst,
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struct scatterlist *src, unsigned int nbytes)
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{
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return crypt(tfm, dst, src, nbytes,
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tfm->__crt_alg->cra_cipher.cia_encrypt,
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ecb_process, NULL);
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}
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static int ecb_decrypt(struct crypto_tfm *tfm,
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struct scatterlist *dst,
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struct scatterlist *src,
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unsigned int nbytes)
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{
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return crypt(tfm, dst, src, nbytes,
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tfm->__crt_alg->cra_cipher.cia_decrypt,
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ecb_process, NULL);
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}
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static int cbc_encrypt(struct crypto_tfm *tfm,
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struct scatterlist *dst,
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struct scatterlist *src,
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unsigned int nbytes)
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{
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return crypt(tfm, dst, src, nbytes,
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tfm->__crt_alg->cra_cipher.cia_encrypt,
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cbc_process_encrypt, tfm->crt_cipher.cit_iv);
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}
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static int cbc_encrypt_iv(struct crypto_tfm *tfm,
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struct scatterlist *dst,
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struct scatterlist *src,
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unsigned int nbytes, u8 *iv)
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{
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return crypt(tfm, dst, src, nbytes,
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tfm->__crt_alg->cra_cipher.cia_encrypt,
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cbc_process_encrypt, iv);
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}
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static int cbc_decrypt(struct crypto_tfm *tfm,
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struct scatterlist *dst,
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struct scatterlist *src,
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unsigned int nbytes)
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{
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return crypt(tfm, dst, src, nbytes,
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tfm->__crt_alg->cra_cipher.cia_decrypt,
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cbc_process_decrypt, tfm->crt_cipher.cit_iv);
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}
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static int cbc_decrypt_iv(struct crypto_tfm *tfm,
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struct scatterlist *dst,
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struct scatterlist *src,
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unsigned int nbytes, u8 *iv)
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{
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return crypt(tfm, dst, src, nbytes,
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tfm->__crt_alg->cra_cipher.cia_decrypt,
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cbc_process_decrypt, iv);
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}
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static int nocrypt(struct crypto_tfm *tfm,
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struct scatterlist *dst,
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struct scatterlist *src,
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unsigned int nbytes)
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{
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return -ENOSYS;
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}
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static int nocrypt_iv(struct crypto_tfm *tfm,
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struct scatterlist *dst,
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struct scatterlist *src,
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unsigned int nbytes, u8 *iv)
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{
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return -ENOSYS;
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}
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int crypto_init_cipher_flags(struct crypto_tfm *tfm, u32 flags)
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{
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u32 mode = flags & CRYPTO_TFM_MODE_MASK;
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tfm->crt_cipher.cit_mode = mode ? mode : CRYPTO_TFM_MODE_ECB;
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if (flags & CRYPTO_TFM_REQ_WEAK_KEY)
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tfm->crt_flags = CRYPTO_TFM_REQ_WEAK_KEY;
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return 0;
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}
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int crypto_init_cipher_ops(struct crypto_tfm *tfm)
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{
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int ret = 0;
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struct cipher_tfm *ops = &tfm->crt_cipher;
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ops->cit_setkey = setkey;
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switch (tfm->crt_cipher.cit_mode) {
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case CRYPTO_TFM_MODE_ECB:
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ops->cit_encrypt = ecb_encrypt;
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ops->cit_decrypt = ecb_decrypt;
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break;
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case CRYPTO_TFM_MODE_CBC:
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ops->cit_encrypt = cbc_encrypt;
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ops->cit_decrypt = cbc_decrypt;
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ops->cit_encrypt_iv = cbc_encrypt_iv;
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ops->cit_decrypt_iv = cbc_decrypt_iv;
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break;
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case CRYPTO_TFM_MODE_CFB:
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ops->cit_encrypt = nocrypt;
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ops->cit_decrypt = nocrypt;
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ops->cit_encrypt_iv = nocrypt_iv;
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ops->cit_decrypt_iv = nocrypt_iv;
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break;
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case CRYPTO_TFM_MODE_CTR:
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ops->cit_encrypt = nocrypt;
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ops->cit_decrypt = nocrypt;
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ops->cit_encrypt_iv = nocrypt_iv;
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ops->cit_decrypt_iv = nocrypt_iv;
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break;
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default:
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BUG();
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}
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if (ops->cit_mode == CRYPTO_TFM_MODE_CBC) {
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switch (crypto_tfm_alg_blocksize(tfm)) {
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case 8:
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ops->cit_xor_block = xor_64;
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break;
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case 16:
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ops->cit_xor_block = xor_128;
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break;
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default:
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printk(KERN_WARNING "%s: block size %u not supported\n",
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crypto_tfm_alg_name(tfm),
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crypto_tfm_alg_blocksize(tfm));
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ret = -EINVAL;
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goto out;
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}
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ops->cit_ivsize = crypto_tfm_alg_blocksize(tfm);
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ops->cit_iv = kmalloc(ops->cit_ivsize, GFP_KERNEL);
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if (ops->cit_iv == NULL)
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ret = -ENOMEM;
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}
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out:
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return ret;
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}
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void crypto_exit_cipher_ops(struct crypto_tfm *tfm)
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{
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if (tfm->crt_cipher.cit_iv)
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kfree(tfm->crt_cipher.cit_iv);
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}
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