269 lines
6.5 KiB
C
269 lines
6.5 KiB
C
/*
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Linux loop encryption enabling module
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Copyright (C) 2002 Herbert Valerio Riedel <hvr@gnu.org>
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Copyright (C) 2003 Fruhwirth Clemens <clemens@endorphin.org>
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This module is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This module is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this module; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/string.h>
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#include <linux/crypto.h>
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#include <linux/blkdev.h>
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#include <linux/loop.h>
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#include <asm/semaphore.h>
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#include <asm/uaccess.h>
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MODULE_LICENSE("GPL");
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MODULE_DESCRIPTION("loop blockdevice transferfunction adaptor / CryptoAPI");
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MODULE_AUTHOR("Herbert Valerio Riedel <hvr@gnu.org>");
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#define LOOP_IV_SECTOR_BITS 9
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#define LOOP_IV_SECTOR_SIZE (1 << LOOP_IV_SECTOR_BITS)
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static int
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cryptoloop_init(struct loop_device *lo, const struct loop_info64 *info)
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{
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int err = -EINVAL;
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char cms[LO_NAME_SIZE]; /* cipher-mode string */
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char *cipher;
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char *mode;
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char *cmsp = cms; /* c-m string pointer */
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struct crypto_tfm *tfm = NULL;
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/* encryption breaks for non sector aligned offsets */
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if (info->lo_offset % LOOP_IV_SECTOR_SIZE)
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goto out;
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strncpy(cms, info->lo_crypt_name, LO_NAME_SIZE);
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cms[LO_NAME_SIZE - 1] = 0;
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cipher = strsep(&cmsp, "-");
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mode = strsep(&cmsp, "-");
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if (mode == NULL || strcmp(mode, "cbc") == 0)
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tfm = crypto_alloc_tfm(cipher, CRYPTO_TFM_MODE_CBC);
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else if (strcmp(mode, "ecb") == 0)
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tfm = crypto_alloc_tfm(cipher, CRYPTO_TFM_MODE_ECB);
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if (tfm == NULL)
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return -EINVAL;
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err = tfm->crt_u.cipher.cit_setkey(tfm, info->lo_encrypt_key,
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info->lo_encrypt_key_size);
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if (err != 0)
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goto out_free_tfm;
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lo->key_data = tfm;
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return 0;
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out_free_tfm:
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crypto_free_tfm(tfm);
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out:
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return err;
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}
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typedef int (*encdec_ecb_t)(struct crypto_tfm *tfm,
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struct scatterlist *sg_out,
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struct scatterlist *sg_in,
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unsigned int nsg);
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static int
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cryptoloop_transfer_ecb(struct loop_device *lo, int cmd,
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struct page *raw_page, unsigned raw_off,
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struct page *loop_page, unsigned loop_off,
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int size, sector_t IV)
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{
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struct crypto_tfm *tfm = (struct crypto_tfm *) lo->key_data;
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struct scatterlist sg_out = { NULL, };
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struct scatterlist sg_in = { NULL, };
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encdec_ecb_t encdecfunc;
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struct page *in_page, *out_page;
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unsigned in_offs, out_offs;
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if (cmd == READ) {
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in_page = raw_page;
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in_offs = raw_off;
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out_page = loop_page;
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out_offs = loop_off;
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encdecfunc = tfm->crt_u.cipher.cit_decrypt;
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} else {
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in_page = loop_page;
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in_offs = loop_off;
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out_page = raw_page;
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out_offs = raw_off;
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encdecfunc = tfm->crt_u.cipher.cit_encrypt;
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}
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while (size > 0) {
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const int sz = min(size, LOOP_IV_SECTOR_SIZE);
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sg_in.page = in_page;
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sg_in.offset = in_offs;
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sg_in.length = sz;
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sg_out.page = out_page;
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sg_out.offset = out_offs;
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sg_out.length = sz;
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encdecfunc(tfm, &sg_out, &sg_in, sz);
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size -= sz;
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in_offs += sz;
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out_offs += sz;
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}
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return 0;
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}
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typedef int (*encdec_cbc_t)(struct crypto_tfm *tfm,
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struct scatterlist *sg_out,
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struct scatterlist *sg_in,
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unsigned int nsg, u8 *iv);
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static int
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cryptoloop_transfer_cbc(struct loop_device *lo, int cmd,
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struct page *raw_page, unsigned raw_off,
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struct page *loop_page, unsigned loop_off,
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int size, sector_t IV)
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{
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struct crypto_tfm *tfm = (struct crypto_tfm *) lo->key_data;
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struct scatterlist sg_out = { NULL, };
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struct scatterlist sg_in = { NULL, };
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encdec_cbc_t encdecfunc;
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struct page *in_page, *out_page;
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unsigned in_offs, out_offs;
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if (cmd == READ) {
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in_page = raw_page;
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in_offs = raw_off;
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out_page = loop_page;
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out_offs = loop_off;
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encdecfunc = tfm->crt_u.cipher.cit_decrypt_iv;
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} else {
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in_page = loop_page;
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in_offs = loop_off;
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out_page = raw_page;
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out_offs = raw_off;
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encdecfunc = tfm->crt_u.cipher.cit_encrypt_iv;
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}
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while (size > 0) {
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const int sz = min(size, LOOP_IV_SECTOR_SIZE);
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u32 iv[4] = { 0, };
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iv[0] = cpu_to_le32(IV & 0xffffffff);
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sg_in.page = in_page;
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sg_in.offset = in_offs;
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sg_in.length = sz;
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sg_out.page = out_page;
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sg_out.offset = out_offs;
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sg_out.length = sz;
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encdecfunc(tfm, &sg_out, &sg_in, sz, (u8 *)iv);
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IV++;
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size -= sz;
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in_offs += sz;
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out_offs += sz;
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}
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return 0;
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}
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static int
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cryptoloop_transfer(struct loop_device *lo, int cmd,
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struct page *raw_page, unsigned raw_off,
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struct page *loop_page, unsigned loop_off,
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int size, sector_t IV)
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{
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struct crypto_tfm *tfm = (struct crypto_tfm *) lo->key_data;
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if(tfm->crt_cipher.cit_mode == CRYPTO_TFM_MODE_ECB)
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{
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lo->transfer = cryptoloop_transfer_ecb;
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return cryptoloop_transfer_ecb(lo, cmd, raw_page, raw_off,
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loop_page, loop_off, size, IV);
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}
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if(tfm->crt_cipher.cit_mode == CRYPTO_TFM_MODE_CBC)
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{
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lo->transfer = cryptoloop_transfer_cbc;
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return cryptoloop_transfer_cbc(lo, cmd, raw_page, raw_off,
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loop_page, loop_off, size, IV);
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}
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/* This is not supposed to happen */
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printk( KERN_ERR "cryptoloop: unsupported cipher mode in cryptoloop_transfer!\n");
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return -EINVAL;
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}
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static int
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cryptoloop_ioctl(struct loop_device *lo, int cmd, unsigned long arg)
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{
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return -EINVAL;
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}
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static int
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cryptoloop_release(struct loop_device *lo)
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{
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struct crypto_tfm *tfm = (struct crypto_tfm *) lo->key_data;
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if (tfm != NULL) {
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crypto_free_tfm(tfm);
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lo->key_data = NULL;
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return 0;
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}
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printk(KERN_ERR "cryptoloop_release(): tfm == NULL?\n");
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return -EINVAL;
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}
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static struct loop_func_table cryptoloop_funcs = {
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.number = LO_CRYPT_CRYPTOAPI,
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.init = cryptoloop_init,
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.ioctl = cryptoloop_ioctl,
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.transfer = cryptoloop_transfer,
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.release = cryptoloop_release,
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.owner = THIS_MODULE
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};
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static int __init
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init_cryptoloop(void)
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{
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int rc = loop_register_transfer(&cryptoloop_funcs);
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if (rc)
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printk(KERN_ERR "cryptoloop: loop_register_transfer failed\n");
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return rc;
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}
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static void __exit
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cleanup_cryptoloop(void)
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{
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if (loop_unregister_transfer(LO_CRYPT_CRYPTOAPI))
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printk(KERN_ERR
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"cryptoloop: loop_unregister_transfer failed\n");
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}
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module_init(init_cryptoloop);
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module_exit(cleanup_cryptoloop);
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