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79bd202987
commit a208fa8f33031b9e0aba44c7d1b7e68eb0cbd29e upstream. We need to consistently enforce that keyed hashes cannot be used without setting the key. To do this we need a reliable way to determine whether a given hash algorithm is keyed or not. AF_ALG currently does this by checking for the presence of a ->setkey() method. However, this is actually slightly broken because the CRC-32 algorithms implement ->setkey() but can also be used without a key. (The CRC-32 "key" is not actually a cryptographic key but rather represents the initial state. If not overridden, then a default initial state is used.) Prepare to fix this by introducing a flag CRYPTO_ALG_OPTIONAL_KEY which indicates that the algorithm has a ->setkey() method, but it is not required to be called. Then set it on all the CRC-32 algorithms. The same also applies to the Adler-32 implementation in Lustre. Also, the cryptd and mcryptd templates have to pass through the flag from their underlying algorithm. Change-Id: Ie0547047b828f276d967e8979cd9176e57c99ac8 Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> [bwh: Backported to 3.2: - Drop changes to nonexistent drivers - There's no CRYPTO_ALG_INTERNAL flag - Adjust filenames] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
160 lines
3.8 KiB
C
160 lines
3.8 KiB
C
/* GPL HEADER START
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*
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 only,
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* as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License version 2 for more details (a copy is included
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* in the LICENSE file that accompanied this code).
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*
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* You should have received a copy of the GNU General Public License
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* version 2 along with this program; If not, see http://www.gnu.org/licenses
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*
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* Please visit http://www.xyratex.com/contact if you need additional
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* information or have any questions.
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*
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* GPL HEADER END
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*/
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/*
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* Copyright 2012 Xyratex Technology Limited
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*/
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/*
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* This is crypto api shash wrappers to crc32_le.
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*/
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#include <linux/crc32.h>
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#include <crypto/internal/hash.h>
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/string.h>
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#include <linux/kernel.h>
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#define CHKSUM_BLOCK_SIZE 1
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#define CHKSUM_DIGEST_SIZE 4
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static u32 __crc32_le(u32 crc, unsigned char const *p, size_t len)
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{
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return crc32_le(crc, p, len);
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}
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/** No default init with ~0 */
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static int crc32_cra_init(struct crypto_tfm *tfm)
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{
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u32 *key = crypto_tfm_ctx(tfm);
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*key = 0;
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return 0;
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}
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/*
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* Setting the seed allows arbitrary accumulators and flexible XOR policy
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* If your algorithm starts with ~0, then XOR with ~0 before you set
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* the seed.
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*/
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static int crc32_setkey(struct crypto_shash *hash, const u8 *key,
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unsigned int keylen)
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{
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u32 *mctx = crypto_shash_ctx(hash);
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if (keylen != sizeof(u32)) {
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crypto_shash_set_flags(hash, CRYPTO_TFM_RES_BAD_KEY_LEN);
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return -EINVAL;
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}
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*mctx = le32_to_cpup((__le32 *)key);
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return 0;
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}
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static int crc32_init(struct shash_desc *desc)
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{
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u32 *mctx = crypto_shash_ctx(desc->tfm);
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u32 *crcp = shash_desc_ctx(desc);
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*crcp = *mctx;
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return 0;
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}
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static int crc32_update(struct shash_desc *desc, const u8 *data,
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unsigned int len)
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{
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u32 *crcp = shash_desc_ctx(desc);
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*crcp = __crc32_le(*crcp, data, len);
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return 0;
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}
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/* No final XOR 0xFFFFFFFF, like crc32_le */
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static int __crc32_finup(u32 *crcp, const u8 *data, unsigned int len,
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u8 *out)
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{
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*(__le32 *)out = cpu_to_le32(__crc32_le(*crcp, data, len));
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return 0;
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}
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static int crc32_finup(struct shash_desc *desc, const u8 *data,
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unsigned int len, u8 *out)
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{
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return __crc32_finup(shash_desc_ctx(desc), data, len, out);
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}
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static int crc32_final(struct shash_desc *desc, u8 *out)
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{
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u32 *crcp = shash_desc_ctx(desc);
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*(__le32 *)out = cpu_to_le32p(crcp);
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return 0;
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}
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static int crc32_digest(struct shash_desc *desc, const u8 *data,
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unsigned int len, u8 *out)
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{
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return __crc32_finup(crypto_shash_ctx(desc->tfm), data, len,
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out);
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}
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static struct shash_alg alg = {
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.setkey = crc32_setkey,
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.init = crc32_init,
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.update = crc32_update,
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.final = crc32_final,
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.finup = crc32_finup,
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.digest = crc32_digest,
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.descsize = sizeof(u32),
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.digestsize = CHKSUM_DIGEST_SIZE,
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.base = {
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.cra_name = "crc32",
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.cra_driver_name = "crc32-table",
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.cra_priority = 100,
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.cra_flags = CRYPTO_ALG_OPTIONAL_KEY,
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.cra_blocksize = CHKSUM_BLOCK_SIZE,
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.cra_ctxsize = sizeof(u32),
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.cra_module = THIS_MODULE,
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.cra_init = crc32_cra_init,
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}
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};
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static int __init crc32_mod_init(void)
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{
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return crypto_register_shash(&alg);
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}
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static void __exit crc32_mod_fini(void)
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{
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crypto_unregister_shash(&alg);
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}
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module_init(crc32_mod_init);
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module_exit(crc32_mod_fini);
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MODULE_AUTHOR("Alexander Boyko <alexander_boyko@xyratex.com>");
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MODULE_DESCRIPTION("CRC32 calculations wrapper for lib/crc32");
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MODULE_LICENSE("GPL");
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MODULE_ALIAS_CRYPTO("crc32");
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