Revision 35cdcbfc5cfc30012b790d9b077bd949ad46f1dd authored by Peng Wang on 26 February 2021, 01:21:44 UTC, committed by Linus Torvalds on 26 February 2021, 17:41:04 UTC
Some max_length wants to hold as large room as possible to ensure enough size to tackle with the biggest NR_CPUS. An example below: kernel/cgroup/cpuset.c: static struct cftype legacy_files[] = { { .name = "cpus", .seq_show = cpuset_common_seq_show, .write = cpuset_write_resmask, .max_write_len = (100U + 6 * NR_CPUS), .private = FILE_CPULIST, }, ... } Link: https://lkml.kernel.org/r/5d4998aa8a8ac7efada2c7daffa9e73559f8b186.1609331255.git.rocking@linux.alibaba.com Signed-off-by: Peng Wang <rocking@linux.alibaba.com> Acked-by: Joe Perches <joe@perches.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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chacha_generic.c
// SPDX-License-Identifier: GPL-2.0-or-later
/*
* ChaCha and XChaCha stream ciphers, including ChaCha20 (RFC7539)
*
* Copyright (C) 2015 Martin Willi
* Copyright (C) 2018 Google LLC
*/
#include <asm/unaligned.h>
#include <crypto/algapi.h>
#include <crypto/internal/chacha.h>
#include <crypto/internal/skcipher.h>
#include <linux/module.h>
static int chacha_stream_xor(struct skcipher_request *req,
const struct chacha_ctx *ctx, const u8 *iv)
{
struct skcipher_walk walk;
u32 state[16];
int err;
err = skcipher_walk_virt(&walk, req, false);
chacha_init_generic(state, ctx->key, iv);
while (walk.nbytes > 0) {
unsigned int nbytes = walk.nbytes;
if (nbytes < walk.total)
nbytes = round_down(nbytes, CHACHA_BLOCK_SIZE);
chacha_crypt_generic(state, walk.dst.virt.addr,
walk.src.virt.addr, nbytes, ctx->nrounds);
err = skcipher_walk_done(&walk, walk.nbytes - nbytes);
}
return err;
}
static int crypto_chacha_crypt(struct skcipher_request *req)
{
struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
struct chacha_ctx *ctx = crypto_skcipher_ctx(tfm);
return chacha_stream_xor(req, ctx, req->iv);
}
static int crypto_xchacha_crypt(struct skcipher_request *req)
{
struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
struct chacha_ctx *ctx = crypto_skcipher_ctx(tfm);
struct chacha_ctx subctx;
u32 state[16];
u8 real_iv[16];
/* Compute the subkey given the original key and first 128 nonce bits */
chacha_init_generic(state, ctx->key, req->iv);
hchacha_block_generic(state, subctx.key, ctx->nrounds);
subctx.nrounds = ctx->nrounds;
/* Build the real IV */
memcpy(&real_iv[0], req->iv + 24, 8); /* stream position */
memcpy(&real_iv[8], req->iv + 16, 8); /* remaining 64 nonce bits */
/* Generate the stream and XOR it with the data */
return chacha_stream_xor(req, &subctx, real_iv);
}
static struct skcipher_alg algs[] = {
{
.base.cra_name = "chacha20",
.base.cra_driver_name = "chacha20-generic",
.base.cra_priority = 100,
.base.cra_blocksize = 1,
.base.cra_ctxsize = sizeof(struct chacha_ctx),
.base.cra_module = THIS_MODULE,
.min_keysize = CHACHA_KEY_SIZE,
.max_keysize = CHACHA_KEY_SIZE,
.ivsize = CHACHA_IV_SIZE,
.chunksize = CHACHA_BLOCK_SIZE,
.setkey = chacha20_setkey,
.encrypt = crypto_chacha_crypt,
.decrypt = crypto_chacha_crypt,
}, {
.base.cra_name = "xchacha20",
.base.cra_driver_name = "xchacha20-generic",
.base.cra_priority = 100,
.base.cra_blocksize = 1,
.base.cra_ctxsize = sizeof(struct chacha_ctx),
.base.cra_module = THIS_MODULE,
.min_keysize = CHACHA_KEY_SIZE,
.max_keysize = CHACHA_KEY_SIZE,
.ivsize = XCHACHA_IV_SIZE,
.chunksize = CHACHA_BLOCK_SIZE,
.setkey = chacha20_setkey,
.encrypt = crypto_xchacha_crypt,
.decrypt = crypto_xchacha_crypt,
}, {
.base.cra_name = "xchacha12",
.base.cra_driver_name = "xchacha12-generic",
.base.cra_priority = 100,
.base.cra_blocksize = 1,
.base.cra_ctxsize = sizeof(struct chacha_ctx),
.base.cra_module = THIS_MODULE,
.min_keysize = CHACHA_KEY_SIZE,
.max_keysize = CHACHA_KEY_SIZE,
.ivsize = XCHACHA_IV_SIZE,
.chunksize = CHACHA_BLOCK_SIZE,
.setkey = chacha12_setkey,
.encrypt = crypto_xchacha_crypt,
.decrypt = crypto_xchacha_crypt,
}
};
static int __init chacha_generic_mod_init(void)
{
return crypto_register_skciphers(algs, ARRAY_SIZE(algs));
}
static void __exit chacha_generic_mod_fini(void)
{
crypto_unregister_skciphers(algs, ARRAY_SIZE(algs));
}
subsys_initcall(chacha_generic_mod_init);
module_exit(chacha_generic_mod_fini);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Martin Willi <martin@strongswan.org>");
MODULE_DESCRIPTION("ChaCha and XChaCha stream ciphers (generic)");
MODULE_ALIAS_CRYPTO("chacha20");
MODULE_ALIAS_CRYPTO("chacha20-generic");
MODULE_ALIAS_CRYPTO("xchacha20");
MODULE_ALIAS_CRYPTO("xchacha20-generic");
MODULE_ALIAS_CRYPTO("xchacha12");
MODULE_ALIAS_CRYPTO("xchacha12-generic");
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