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![Eric Biggers](/assets/img/avatar_default.png)
CRYPTO_ALG_NEED_FALLBACK is handled inconsistently. When it's requested to be clear, some templates propagate that request to child algorithms, while others don't. It's apparently desired for NEED_FALLBACK to be propagated, to avoid deadlocks where a module tries to load itself while it's being initialized, and to avoid unnecessarily complex fallback chains where we have e.g. cbc-aes-$driver falling back to cbc(aes-$driver) where aes-$driver itself falls back to aes-generic, instead of cbc-aes-$driver simply falling back to cbc(aes-generic). There have been a number of fixes to this effect: commit89027579bc
("crypto: xts - Propagate NEED_FALLBACK bit") commitd2c2a85cfe
("crypto: ctr - Propagate NEED_FALLBACK bit") commite6c2e65c70
("crypto: cbc - Propagate NEED_FALLBACK bit") But it seems that other templates can have the same problems too. To avoid this whack-a-mole, just add NEED_FALLBACK to INHERITED_FLAGS so that it's always inherited. Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
360 lines
9.5 KiB
C
360 lines
9.5 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* CTR: Counter mode
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*
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* (C) Copyright IBM Corp. 2007 - Joy Latten <latten@us.ibm.com>
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*/
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#include <crypto/algapi.h>
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#include <crypto/ctr.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/module.h>
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#include <linux/slab.h>
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struct crypto_rfc3686_ctx {
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struct crypto_skcipher *child;
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u8 nonce[CTR_RFC3686_NONCE_SIZE];
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};
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struct crypto_rfc3686_req_ctx {
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u8 iv[CTR_RFC3686_BLOCK_SIZE];
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struct skcipher_request subreq CRYPTO_MINALIGN_ATTR;
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};
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static void crypto_ctr_crypt_final(struct skcipher_walk *walk,
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struct crypto_cipher *tfm)
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{
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unsigned int bsize = crypto_cipher_blocksize(tfm);
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unsigned long alignmask = crypto_cipher_alignmask(tfm);
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u8 *ctrblk = walk->iv;
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u8 tmp[MAX_CIPHER_BLOCKSIZE + MAX_CIPHER_ALIGNMASK];
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u8 *keystream = PTR_ALIGN(tmp + 0, alignmask + 1);
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u8 *src = walk->src.virt.addr;
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u8 *dst = walk->dst.virt.addr;
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unsigned int nbytes = walk->nbytes;
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crypto_cipher_encrypt_one(tfm, keystream, ctrblk);
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crypto_xor_cpy(dst, keystream, src, nbytes);
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crypto_inc(ctrblk, bsize);
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}
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static int crypto_ctr_crypt_segment(struct skcipher_walk *walk,
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struct crypto_cipher *tfm)
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{
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void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
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crypto_cipher_alg(tfm)->cia_encrypt;
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unsigned int bsize = crypto_cipher_blocksize(tfm);
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u8 *ctrblk = walk->iv;
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u8 *src = walk->src.virt.addr;
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u8 *dst = walk->dst.virt.addr;
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unsigned int nbytes = walk->nbytes;
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do {
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/* create keystream */
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fn(crypto_cipher_tfm(tfm), dst, ctrblk);
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crypto_xor(dst, src, bsize);
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/* increment counter in counterblock */
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crypto_inc(ctrblk, bsize);
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src += bsize;
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dst += bsize;
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} while ((nbytes -= bsize) >= bsize);
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return nbytes;
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}
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static int crypto_ctr_crypt_inplace(struct skcipher_walk *walk,
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struct crypto_cipher *tfm)
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{
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void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
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crypto_cipher_alg(tfm)->cia_encrypt;
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unsigned int bsize = crypto_cipher_blocksize(tfm);
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unsigned long alignmask = crypto_cipher_alignmask(tfm);
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unsigned int nbytes = walk->nbytes;
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u8 *ctrblk = walk->iv;
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u8 *src = walk->src.virt.addr;
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u8 tmp[MAX_CIPHER_BLOCKSIZE + MAX_CIPHER_ALIGNMASK];
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u8 *keystream = PTR_ALIGN(tmp + 0, alignmask + 1);
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do {
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/* create keystream */
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fn(crypto_cipher_tfm(tfm), keystream, ctrblk);
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crypto_xor(src, keystream, bsize);
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/* increment counter in counterblock */
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crypto_inc(ctrblk, bsize);
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src += bsize;
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} while ((nbytes -= bsize) >= bsize);
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return nbytes;
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}
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static int crypto_ctr_crypt(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_cipher *cipher = skcipher_cipher_simple(tfm);
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const unsigned int bsize = crypto_cipher_blocksize(cipher);
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struct skcipher_walk walk;
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unsigned int nbytes;
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int err;
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err = skcipher_walk_virt(&walk, req, false);
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while (walk.nbytes >= bsize) {
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if (walk.src.virt.addr == walk.dst.virt.addr)
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nbytes = crypto_ctr_crypt_inplace(&walk, cipher);
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else
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nbytes = crypto_ctr_crypt_segment(&walk, cipher);
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err = skcipher_walk_done(&walk, nbytes);
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}
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if (walk.nbytes) {
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crypto_ctr_crypt_final(&walk, cipher);
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err = skcipher_walk_done(&walk, 0);
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}
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return err;
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}
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static int crypto_ctr_create(struct crypto_template *tmpl, struct rtattr **tb)
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{
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struct skcipher_instance *inst;
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struct crypto_alg *alg;
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int err;
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inst = skcipher_alloc_instance_simple(tmpl, tb);
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if (IS_ERR(inst))
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return PTR_ERR(inst);
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alg = skcipher_ialg_simple(inst);
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/* Block size must be >= 4 bytes. */
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err = -EINVAL;
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if (alg->cra_blocksize < 4)
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goto out_free_inst;
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/* If this is false we'd fail the alignment of crypto_inc. */
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if (alg->cra_blocksize % 4)
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goto out_free_inst;
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/* CTR mode is a stream cipher. */
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inst->alg.base.cra_blocksize = 1;
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/*
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* To simplify the implementation, configure the skcipher walk to only
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* give a partial block at the very end, never earlier.
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*/
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inst->alg.chunksize = alg->cra_blocksize;
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inst->alg.encrypt = crypto_ctr_crypt;
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inst->alg.decrypt = crypto_ctr_crypt;
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err = skcipher_register_instance(tmpl, inst);
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if (err) {
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out_free_inst:
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inst->free(inst);
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}
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return err;
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}
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static int crypto_rfc3686_setkey(struct crypto_skcipher *parent,
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const u8 *key, unsigned int keylen)
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{
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struct crypto_rfc3686_ctx *ctx = crypto_skcipher_ctx(parent);
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struct crypto_skcipher *child = ctx->child;
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/* the nonce is stored in bytes at end of key */
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if (keylen < CTR_RFC3686_NONCE_SIZE)
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return -EINVAL;
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memcpy(ctx->nonce, key + (keylen - CTR_RFC3686_NONCE_SIZE),
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CTR_RFC3686_NONCE_SIZE);
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keylen -= CTR_RFC3686_NONCE_SIZE;
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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 int crypto_rfc3686_crypt(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_rfc3686_ctx *ctx = crypto_skcipher_ctx(tfm);
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struct crypto_skcipher *child = ctx->child;
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unsigned long align = crypto_skcipher_alignmask(tfm);
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struct crypto_rfc3686_req_ctx *rctx =
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(void *)PTR_ALIGN((u8 *)skcipher_request_ctx(req), align + 1);
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struct skcipher_request *subreq = &rctx->subreq;
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u8 *iv = rctx->iv;
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/* set up counter block */
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memcpy(iv, ctx->nonce, CTR_RFC3686_NONCE_SIZE);
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memcpy(iv + CTR_RFC3686_NONCE_SIZE, req->iv, CTR_RFC3686_IV_SIZE);
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/* initialize counter portion of counter block */
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*(__be32 *)(iv + CTR_RFC3686_NONCE_SIZE + CTR_RFC3686_IV_SIZE) =
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cpu_to_be32(1);
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skcipher_request_set_tfm(subreq, child);
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skcipher_request_set_callback(subreq, req->base.flags,
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req->base.complete, req->base.data);
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skcipher_request_set_crypt(subreq, req->src, req->dst,
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req->cryptlen, iv);
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return crypto_skcipher_encrypt(subreq);
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}
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static int crypto_rfc3686_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_rfc3686_ctx *ctx = crypto_skcipher_ctx(tfm);
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struct crypto_skcipher *cipher;
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unsigned long align;
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unsigned int reqsize;
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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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align &= ~(crypto_tfm_ctx_alignment() - 1);
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reqsize = align + sizeof(struct crypto_rfc3686_req_ctx) +
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crypto_skcipher_reqsize(cipher);
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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_rfc3686_exit_tfm(struct crypto_skcipher *tfm)
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{
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struct crypto_rfc3686_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_rfc3686_free(struct skcipher_instance *inst)
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{
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struct crypto_skcipher_spawn *spawn = skcipher_instance_ctx(inst);
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crypto_drop_skcipher(spawn);
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kfree(inst);
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}
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static int crypto_rfc3686_create(struct crypto_template *tmpl,
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struct rtattr **tb)
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{
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struct skcipher_instance *inst;
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struct skcipher_alg *alg;
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struct crypto_skcipher_spawn *spawn;
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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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/* We only support 16-byte blocks. */
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err = -EINVAL;
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if (crypto_skcipher_alg_ivsize(alg) != CTR_RFC3686_BLOCK_SIZE)
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goto err_free_inst;
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/* Not a stream cipher? */
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if (alg->base.cra_blocksize != 1)
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goto err_free_inst;
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err = -ENAMETOOLONG;
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if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
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"rfc3686(%s)", alg->base.cra_name) >= CRYPTO_MAX_ALG_NAME)
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goto err_free_inst;
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if (snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME,
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"rfc3686(%s)", alg->base.cra_driver_name) >=
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CRYPTO_MAX_ALG_NAME)
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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 = 1;
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inst->alg.base.cra_alignmask = alg->base.cra_alignmask;
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inst->alg.ivsize = CTR_RFC3686_IV_SIZE;
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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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CTR_RFC3686_NONCE_SIZE;
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inst->alg.max_keysize = crypto_skcipher_alg_max_keysize(alg) +
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CTR_RFC3686_NONCE_SIZE;
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inst->alg.setkey = crypto_rfc3686_setkey;
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inst->alg.encrypt = crypto_rfc3686_crypt;
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inst->alg.decrypt = crypto_rfc3686_crypt;
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inst->alg.base.cra_ctxsize = sizeof(struct crypto_rfc3686_ctx);
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inst->alg.init = crypto_rfc3686_init_tfm;
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inst->alg.exit = crypto_rfc3686_exit_tfm;
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inst->free = crypto_rfc3686_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_rfc3686_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_ctr_tmpls[] = {
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{
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.name = "ctr",
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.create = crypto_ctr_create,
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.module = THIS_MODULE,
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}, {
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.name = "rfc3686",
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.create = crypto_rfc3686_create,
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.module = THIS_MODULE,
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},
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};
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static int __init crypto_ctr_module_init(void)
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{
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return crypto_register_templates(crypto_ctr_tmpls,
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ARRAY_SIZE(crypto_ctr_tmpls));
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}
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static void __exit crypto_ctr_module_exit(void)
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{
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crypto_unregister_templates(crypto_ctr_tmpls,
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ARRAY_SIZE(crypto_ctr_tmpls));
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}
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subsys_initcall(crypto_ctr_module_init);
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module_exit(crypto_ctr_module_exit);
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MODULE_LICENSE("GPL");
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MODULE_DESCRIPTION("CTR block cipher mode of operation");
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MODULE_ALIAS_CRYPTO("rfc3686");
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MODULE_ALIAS_CRYPTO("ctr");
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