mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-11-24 02:50:53 +07:00
crypto: ofb - fix handling partial blocks and make thread-safe
Fix multiple bugs in the OFB implementation:
1. It stored the per-request state 'cnt' in the tfm context, which can be
used by multiple threads concurrently (e.g. via AF_ALG).
2. It didn't support messages not a multiple of the block cipher size,
despite being a stream cipher.
3. It didn't set cra_blocksize to 1 to indicate it is a stream cipher.
To fix these, set the 'chunksize' property to the cipher block size to
guarantee that when walking through the scatterlist, a partial block can
only occur at the end. Then change the implementation to XOR a block at
a time at first, then XOR the partial block at the end if needed. This
is the same way CTR and CFB are implemented. As a bonus, this also
improves performance in most cases over the current approach.
Fixes: e497c51896 ("crypto: ofb - add output feedback mode")
Cc: <stable@vger.kernel.org> # v4.20+
Cc: Gilad Ben-Yossef <gilad@benyossef.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Gilad Ben-Yossef <gilad@benyossef.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Eric Biggers
Herbert Xu
parent
6c2e322b36
commit
b3e3e2db7d
93
crypto/ofb.c
93
crypto/ofb.c
@ -5,9 +5,6 @@
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*
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* Copyright (C) 2018 ARM Limited or its affiliates.
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* All rights reserved.
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*
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* Based loosely on public domain code gleaned from libtomcrypt
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* (https://github.com/libtom/libtomcrypt).
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*/
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#include <crypto/algapi.h>
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@ -21,7 +18,6 @@
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struct crypto_ofb_ctx {
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struct crypto_cipher *child;
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int cnt;
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};
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@ -41,58 +37,40 @@ static int crypto_ofb_setkey(struct crypto_skcipher *parent, const u8 *key,
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return err;
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}
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static int crypto_ofb_encrypt_segment(struct crypto_ofb_ctx *ctx,
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struct skcipher_walk *walk,
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struct crypto_cipher *tfm)
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static int crypto_ofb_crypt(struct skcipher_request *req)
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{
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int bsize = crypto_cipher_blocksize(tfm);
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int nbytes = walk->nbytes;
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u8 *src = walk->src.virt.addr;
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u8 *dst = walk->dst.virt.addr;
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u8 *iv = walk->iv;
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do {
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if (ctx->cnt == bsize) {
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if (nbytes < bsize)
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break;
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crypto_cipher_encrypt_one(tfm, iv, iv);
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ctx->cnt = 0;
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}
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*dst = *src ^ iv[ctx->cnt];
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src++;
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dst++;
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ctx->cnt++;
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} while (--nbytes);
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return nbytes;
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}
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static int crypto_ofb_encrypt(struct skcipher_request *req)
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{
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struct skcipher_walk walk;
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struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
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unsigned int bsize;
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struct crypto_ofb_ctx *ctx = crypto_skcipher_ctx(tfm);
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struct crypto_cipher *child = ctx->child;
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int ret = 0;
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struct crypto_cipher *cipher = ctx->child;
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const unsigned int bsize = crypto_cipher_blocksize(cipher);
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struct skcipher_walk walk;
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int err;
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bsize = crypto_cipher_blocksize(child);
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ctx->cnt = bsize;
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err = skcipher_walk_virt(&walk, req, false);
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ret = skcipher_walk_virt(&walk, req, false);
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while (walk.nbytes >= bsize) {
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const u8 *src = walk.src.virt.addr;
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u8 *dst = walk.dst.virt.addr;
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u8 * const iv = walk.iv;
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unsigned int nbytes = walk.nbytes;
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while (walk.nbytes) {
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ret = crypto_ofb_encrypt_segment(ctx, &walk, child);
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ret = skcipher_walk_done(&walk, ret);
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do {
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crypto_cipher_encrypt_one(cipher, iv, iv);
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crypto_xor_cpy(dst, src, iv, bsize);
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dst += bsize;
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src += bsize;
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} while ((nbytes -= bsize) >= bsize);
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err = skcipher_walk_done(&walk, nbytes);
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}
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return ret;
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}
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/* OFB encrypt and decrypt are identical */
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static int crypto_ofb_decrypt(struct skcipher_request *req)
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{
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return crypto_ofb_encrypt(req);
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if (walk.nbytes) {
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crypto_cipher_encrypt_one(cipher, walk.iv, walk.iv);
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crypto_xor_cpy(walk.dst.virt.addr, walk.src.virt.addr, walk.iv,
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walk.nbytes);
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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_ofb_init_tfm(struct crypto_skcipher *tfm)
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@ -165,12 +143,17 @@ static int crypto_ofb_create(struct crypto_template *tmpl, struct rtattr **tb)
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if (err)
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goto err_drop_spawn;
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inst->alg.base.cra_priority = alg->cra_priority;
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inst->alg.base.cra_blocksize = alg->cra_blocksize;
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inst->alg.base.cra_alignmask = alg->cra_alignmask;
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/* OFB mode is a stream cipher. */
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inst->alg.base.cra_blocksize = 1;
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/* We access the data as u32s when xoring. */
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inst->alg.base.cra_alignmask |= __alignof__(u32) - 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.base.cra_priority = alg->cra_priority;
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inst->alg.base.cra_alignmask = alg->cra_alignmask;
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inst->alg.ivsize = alg->cra_blocksize;
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inst->alg.min_keysize = alg->cra_cipher.cia_min_keysize;
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@ -182,8 +165,8 @@ static int crypto_ofb_create(struct crypto_template *tmpl, struct rtattr **tb)
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inst->alg.exit = crypto_ofb_exit_tfm;
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inst->alg.setkey = crypto_ofb_setkey;
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inst->alg.encrypt = crypto_ofb_encrypt;
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inst->alg.decrypt = crypto_ofb_decrypt;
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inst->alg.encrypt = crypto_ofb_crypt;
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inst->alg.decrypt = crypto_ofb_crypt;
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inst->free = crypto_ofb_free;
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@ -16681,8 +16681,7 @@ static const struct cipher_testvec aes_ctr_rfc3686_tv_template[] = {
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};
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static const struct cipher_testvec aes_ofb_tv_template[] = {
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/* From NIST Special Publication 800-38A, Appendix F.5 */
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{
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{ /* From NIST Special Publication 800-38A, Appendix F.5 */
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.key = "\x2b\x7e\x15\x16\x28\xae\xd2\xa6"
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"\xab\xf7\x15\x88\x09\xcf\x4f\x3c",
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.klen = 16,
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@ -16705,6 +16704,31 @@ static const struct cipher_testvec aes_ofb_tv_template[] = {
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"\x30\x4c\x65\x28\xf6\x59\xc7\x78"
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"\x66\xa5\x10\xd9\xc1\xd6\xae\x5e",
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.len = 64,
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.also_non_np = 1,
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.np = 2,
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.tap = { 31, 33 },
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}, { /* > 16 bytes, not a multiple of 16 bytes */
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.key = "\x2b\x7e\x15\x16\x28\xae\xd2\xa6"
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"\xab\xf7\x15\x88\x09\xcf\x4f\x3c",
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.klen = 16,
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.iv = "\x00\x01\x02\x03\x04\x05\x06\x07"
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"\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f",
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.ptext = "\x6b\xc1\xbe\xe2\x2e\x40\x9f\x96"
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"\xe9\x3d\x7e\x11\x73\x93\x17\x2a"
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"\xae",
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.ctext = "\x3b\x3f\xd9\x2e\xb7\x2d\xad\x20"
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"\x33\x34\x49\xf8\xe8\x3c\xfb\x4a"
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"\x77",
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.len = 17,
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}, { /* < 16 bytes */
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.key = "\x2b\x7e\x15\x16\x28\xae\xd2\xa6"
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"\xab\xf7\x15\x88\x09\xcf\x4f\x3c",
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.klen = 16,
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.iv = "\x00\x01\x02\x03\x04\x05\x06\x07"
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"\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f",
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.ptext = "\x6b\xc1\xbe\xe2\x2e\x40\x9f",
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.ctext = "\x3b\x3f\xd9\x2e\xb7\x2d\xad",
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.len = 7,
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}
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};
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