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![Eric Biggers](/assets/img/avatar_default.png)
The flag CRYPTO_ALG_ASYNC is "inherited" in the sense that when a template is instantiated, the template will have CRYPTO_ALG_ASYNC set if any of the algorithms it uses has CRYPTO_ALG_ASYNC set. We'd like to add a second flag (CRYPTO_ALG_ALLOCATES_MEMORY) that gets "inherited" in the same way. This is difficult because the handling of CRYPTO_ALG_ASYNC is hardcoded everywhere. Address this by: - Add CRYPTO_ALG_INHERITED_FLAGS, which contains the set of flags that have these inheritance semantics. - Add crypto_algt_inherited_mask(), for use by template ->create() methods. It returns any of these flags that the user asked to be unset and thus must be passed in the 'mask' to crypto_grab_*(). - Also modify crypto_check_attr_type() to handle computing the 'mask' so that most templates can just use this. - Make crypto_grab_*() propagate these flags to the template instance being created so that templates don't have to do this themselves. Make crypto/simd.c propagate these flags too, since it "wraps" another algorithm, similar to a template. Based on a patch by Mikulas Patocka <mpatocka@redhat.com> (https://lore.kernel.org/r/alpine.LRH.2.02.2006301414580.30526@file01.intranet.prod.int.rdu2.redhat.com). Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
410 lines
12 KiB
C
410 lines
12 KiB
C
/*
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* CTS: Cipher Text Stealing mode
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*
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* COPYRIGHT (c) 2008
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* The Regents of the University of Michigan
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* ALL RIGHTS RESERVED
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*
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* Permission is granted to use, copy, create derivative works
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* and redistribute this software and such derivative works
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* for any purpose, so long as the name of The University of
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* Michigan is not used in any advertising or publicity
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* pertaining to the use of distribution of this software
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* without specific, written prior authorization. If the
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* above copyright notice or any other identification of the
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* University of Michigan is included in any copy of any
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* portion of this software, then the disclaimer below must
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* also be included.
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*
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* THIS SOFTWARE IS PROVIDED AS IS, WITHOUT REPRESENTATION
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* FROM THE UNIVERSITY OF MICHIGAN AS TO ITS FITNESS FOR ANY
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* PURPOSE, AND WITHOUT WARRANTY BY THE UNIVERSITY OF
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* MICHIGAN OF ANY KIND, EITHER EXPRESS OR IMPLIED, INCLUDING
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* WITHOUT LIMITATION THE IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE
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* REGENTS OF THE UNIVERSITY OF MICHIGAN SHALL NOT BE LIABLE
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* FOR ANY DAMAGES, INCLUDING SPECIAL, INDIRECT, INCIDENTAL, OR
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* CONSEQUENTIAL DAMAGES, WITH RESPECT TO ANY CLAIM ARISING
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* OUT OF OR IN CONNECTION WITH THE USE OF THE SOFTWARE, EVEN
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* IF IT HAS BEEN OR IS HEREAFTER ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGES.
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*/
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/* Derived from various:
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* Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au>
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*/
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/*
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* This is the Cipher Text Stealing mode as described by
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* Section 8 of rfc2040 and referenced by rfc3962.
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* rfc3962 includes errata information in its Appendix A.
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*/
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#include <crypto/algapi.h>
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#include <crypto/internal/skcipher.h>
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#include <linux/err.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/log2.h>
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#include <linux/module.h>
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#include <linux/scatterlist.h>
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#include <crypto/scatterwalk.h>
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#include <linux/slab.h>
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#include <linux/compiler.h>
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struct crypto_cts_ctx {
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struct crypto_skcipher *child;
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};
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struct crypto_cts_reqctx {
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struct scatterlist sg[2];
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unsigned offset;
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struct skcipher_request subreq;
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};
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static inline u8 *crypto_cts_reqctx_space(struct skcipher_request *req)
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{
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struct crypto_cts_reqctx *rctx = skcipher_request_ctx(req);
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struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
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struct crypto_cts_ctx *ctx = crypto_skcipher_ctx(tfm);
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struct crypto_skcipher *child = ctx->child;
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return PTR_ALIGN((u8 *)(rctx + 1) + crypto_skcipher_reqsize(child),
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crypto_skcipher_alignmask(tfm) + 1);
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}
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static int crypto_cts_setkey(struct crypto_skcipher *parent, const u8 *key,
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unsigned int keylen)
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{
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struct crypto_cts_ctx *ctx = crypto_skcipher_ctx(parent);
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struct crypto_skcipher *child = ctx->child;
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crypto_skcipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
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crypto_skcipher_set_flags(child, crypto_skcipher_get_flags(parent) &
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CRYPTO_TFM_REQ_MASK);
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return crypto_skcipher_setkey(child, key, keylen);
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}
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static void cts_cbc_crypt_done(struct crypto_async_request *areq, int err)
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{
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struct skcipher_request *req = areq->data;
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if (err == -EINPROGRESS)
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return;
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skcipher_request_complete(req, err);
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}
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static int cts_cbc_encrypt(struct skcipher_request *req)
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{
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struct crypto_cts_reqctx *rctx = skcipher_request_ctx(req);
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struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
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struct skcipher_request *subreq = &rctx->subreq;
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int bsize = crypto_skcipher_blocksize(tfm);
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u8 d[MAX_CIPHER_BLOCKSIZE * 2] __aligned(__alignof__(u32));
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struct scatterlist *sg;
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unsigned int offset;
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int lastn;
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offset = rctx->offset;
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lastn = req->cryptlen - offset;
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sg = scatterwalk_ffwd(rctx->sg, req->dst, offset - bsize);
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scatterwalk_map_and_copy(d + bsize, sg, 0, bsize, 0);
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memset(d, 0, bsize);
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scatterwalk_map_and_copy(d, req->src, offset, lastn, 0);
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scatterwalk_map_and_copy(d, sg, 0, bsize + lastn, 1);
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memzero_explicit(d, sizeof(d));
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skcipher_request_set_callback(subreq, req->base.flags &
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CRYPTO_TFM_REQ_MAY_BACKLOG,
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cts_cbc_crypt_done, req);
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skcipher_request_set_crypt(subreq, sg, sg, bsize, req->iv);
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return crypto_skcipher_encrypt(subreq);
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}
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static void crypto_cts_encrypt_done(struct crypto_async_request *areq, int err)
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{
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struct skcipher_request *req = areq->data;
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if (err)
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goto out;
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err = cts_cbc_encrypt(req);
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if (err == -EINPROGRESS || err == -EBUSY)
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return;
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out:
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skcipher_request_complete(req, err);
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}
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static int crypto_cts_encrypt(struct skcipher_request *req)
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{
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struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
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struct crypto_cts_reqctx *rctx = skcipher_request_ctx(req);
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struct crypto_cts_ctx *ctx = crypto_skcipher_ctx(tfm);
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struct skcipher_request *subreq = &rctx->subreq;
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int bsize = crypto_skcipher_blocksize(tfm);
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unsigned int nbytes = req->cryptlen;
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unsigned int offset;
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skcipher_request_set_tfm(subreq, ctx->child);
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if (nbytes < bsize)
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return -EINVAL;
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if (nbytes == bsize) {
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skcipher_request_set_callback(subreq, req->base.flags,
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req->base.complete,
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req->base.data);
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skcipher_request_set_crypt(subreq, req->src, req->dst, nbytes,
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req->iv);
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return crypto_skcipher_encrypt(subreq);
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}
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offset = rounddown(nbytes - 1, bsize);
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rctx->offset = offset;
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skcipher_request_set_callback(subreq, req->base.flags,
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crypto_cts_encrypt_done, req);
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skcipher_request_set_crypt(subreq, req->src, req->dst,
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offset, req->iv);
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return crypto_skcipher_encrypt(subreq) ?:
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cts_cbc_encrypt(req);
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}
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static int cts_cbc_decrypt(struct skcipher_request *req)
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{
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struct crypto_cts_reqctx *rctx = skcipher_request_ctx(req);
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struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
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struct skcipher_request *subreq = &rctx->subreq;
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int bsize = crypto_skcipher_blocksize(tfm);
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u8 d[MAX_CIPHER_BLOCKSIZE * 2] __aligned(__alignof__(u32));
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struct scatterlist *sg;
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unsigned int offset;
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u8 *space;
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int lastn;
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offset = rctx->offset;
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lastn = req->cryptlen - offset;
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sg = scatterwalk_ffwd(rctx->sg, req->dst, offset - bsize);
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/* 1. Decrypt Cn-1 (s) to create Dn */
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scatterwalk_map_and_copy(d + bsize, sg, 0, bsize, 0);
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space = crypto_cts_reqctx_space(req);
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crypto_xor(d + bsize, space, bsize);
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/* 2. Pad Cn with zeros at the end to create C of length BB */
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memset(d, 0, bsize);
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scatterwalk_map_and_copy(d, req->src, offset, lastn, 0);
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/* 3. Exclusive-or Dn with C to create Xn */
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/* 4. Select the first Ln bytes of Xn to create Pn */
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crypto_xor(d + bsize, d, lastn);
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/* 5. Append the tail (BB - Ln) bytes of Xn to Cn to create En */
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memcpy(d + lastn, d + bsize + lastn, bsize - lastn);
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/* 6. Decrypt En to create Pn-1 */
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scatterwalk_map_and_copy(d, sg, 0, bsize + lastn, 1);
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memzero_explicit(d, sizeof(d));
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skcipher_request_set_callback(subreq, req->base.flags &
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CRYPTO_TFM_REQ_MAY_BACKLOG,
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cts_cbc_crypt_done, req);
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skcipher_request_set_crypt(subreq, sg, sg, bsize, space);
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return crypto_skcipher_decrypt(subreq);
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}
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static void crypto_cts_decrypt_done(struct crypto_async_request *areq, int err)
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{
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struct skcipher_request *req = areq->data;
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if (err)
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goto out;
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err = cts_cbc_decrypt(req);
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if (err == -EINPROGRESS || err == -EBUSY)
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return;
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out:
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skcipher_request_complete(req, err);
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}
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static int crypto_cts_decrypt(struct skcipher_request *req)
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{
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struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
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struct crypto_cts_reqctx *rctx = skcipher_request_ctx(req);
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struct crypto_cts_ctx *ctx = crypto_skcipher_ctx(tfm);
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struct skcipher_request *subreq = &rctx->subreq;
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int bsize = crypto_skcipher_blocksize(tfm);
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unsigned int nbytes = req->cryptlen;
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unsigned int offset;
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u8 *space;
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skcipher_request_set_tfm(subreq, ctx->child);
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if (nbytes < bsize)
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return -EINVAL;
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if (nbytes == bsize) {
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skcipher_request_set_callback(subreq, req->base.flags,
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req->base.complete,
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req->base.data);
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skcipher_request_set_crypt(subreq, req->src, req->dst, nbytes,
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req->iv);
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return crypto_skcipher_decrypt(subreq);
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}
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skcipher_request_set_callback(subreq, req->base.flags,
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crypto_cts_decrypt_done, req);
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space = crypto_cts_reqctx_space(req);
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offset = rounddown(nbytes - 1, bsize);
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rctx->offset = offset;
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if (offset <= bsize)
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memcpy(space, req->iv, bsize);
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else
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scatterwalk_map_and_copy(space, req->src, offset - 2 * bsize,
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bsize, 0);
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skcipher_request_set_crypt(subreq, req->src, req->dst,
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offset, req->iv);
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return crypto_skcipher_decrypt(subreq) ?:
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cts_cbc_decrypt(req);
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}
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static int crypto_cts_init_tfm(struct crypto_skcipher *tfm)
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{
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struct skcipher_instance *inst = skcipher_alg_instance(tfm);
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struct crypto_skcipher_spawn *spawn = skcipher_instance_ctx(inst);
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struct crypto_cts_ctx *ctx = crypto_skcipher_ctx(tfm);
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struct crypto_skcipher *cipher;
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unsigned reqsize;
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unsigned bsize;
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unsigned align;
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cipher = crypto_spawn_skcipher(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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align = crypto_skcipher_alignmask(tfm);
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bsize = crypto_skcipher_blocksize(cipher);
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reqsize = ALIGN(sizeof(struct crypto_cts_reqctx) +
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crypto_skcipher_reqsize(cipher),
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crypto_tfm_ctx_alignment()) +
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(align & ~(crypto_tfm_ctx_alignment() - 1)) + bsize;
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crypto_skcipher_set_reqsize(tfm, reqsize);
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return 0;
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}
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static void crypto_cts_exit_tfm(struct crypto_skcipher *tfm)
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{
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struct crypto_cts_ctx *ctx = crypto_skcipher_ctx(tfm);
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crypto_free_skcipher(ctx->child);
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}
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static void crypto_cts_free(struct skcipher_instance *inst)
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{
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crypto_drop_skcipher(skcipher_instance_ctx(inst));
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kfree(inst);
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}
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static int crypto_cts_create(struct crypto_template *tmpl, struct rtattr **tb)
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{
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struct crypto_skcipher_spawn *spawn;
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struct skcipher_instance *inst;
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struct skcipher_alg *alg;
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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_SKCIPHER, &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 = skcipher_instance_ctx(inst);
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err = crypto_grab_skcipher(spawn, skcipher_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_skcipher_alg(spawn);
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err = -EINVAL;
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if (crypto_skcipher_alg_ivsize(alg) != alg->base.cra_blocksize)
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goto err_free_inst;
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if (strncmp(alg->base.cra_name, "cbc(", 4))
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goto err_free_inst;
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err = crypto_inst_setname(skcipher_crypto_instance(inst), "cts",
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&alg->base);
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if (err)
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goto err_free_inst;
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inst->alg.base.cra_priority = alg->base.cra_priority;
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inst->alg.base.cra_blocksize = alg->base.cra_blocksize;
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inst->alg.base.cra_alignmask = alg->base.cra_alignmask;
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inst->alg.ivsize = alg->base.cra_blocksize;
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inst->alg.chunksize = crypto_skcipher_alg_chunksize(alg);
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inst->alg.min_keysize = crypto_skcipher_alg_min_keysize(alg);
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inst->alg.max_keysize = crypto_skcipher_alg_max_keysize(alg);
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inst->alg.base.cra_ctxsize = sizeof(struct crypto_cts_ctx);
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inst->alg.init = crypto_cts_init_tfm;
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inst->alg.exit = crypto_cts_exit_tfm;
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inst->alg.setkey = crypto_cts_setkey;
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inst->alg.encrypt = crypto_cts_encrypt;
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inst->alg.decrypt = crypto_cts_decrypt;
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inst->free = crypto_cts_free;
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err = skcipher_register_instance(tmpl, inst);
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if (err) {
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err_free_inst:
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crypto_cts_free(inst);
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}
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return err;
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}
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static struct crypto_template crypto_cts_tmpl = {
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.name = "cts",
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.create = crypto_cts_create,
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.module = THIS_MODULE,
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};
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static int __init crypto_cts_module_init(void)
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{
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return crypto_register_template(&crypto_cts_tmpl);
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}
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static void __exit crypto_cts_module_exit(void)
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{
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crypto_unregister_template(&crypto_cts_tmpl);
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}
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subsys_initcall(crypto_cts_module_init);
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module_exit(crypto_cts_module_exit);
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MODULE_LICENSE("Dual BSD/GPL");
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MODULE_DESCRIPTION("CTS-CBC CipherText Stealing for CBC");
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MODULE_ALIAS_CRYPTO("cts");
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