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