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![Eric Biggers](/assets/img/avatar_default.png)
The CRYPTO_TFM_RES_BAD_KEY_LEN flag was apparently meant as a way to make the ->setkey() functions provide more information about errors. However, no one actually checks for this flag, which makes it pointless. Also, many algorithms fail to set this flag when given a bad length key. Reviewing just the generic implementations, this is the case for aes-fixed-time, cbcmac, echainiv, nhpoly1305, pcrypt, rfc3686, rfc4309, rfc7539, rfc7539esp, salsa20, seqiv, and xcbc. But there are probably many more in arch/*/crypto/ and drivers/crypto/. Some algorithms can even set this flag when the key is the correct length. For example, authenc and authencesn set it when the key payload is malformed in any way (not just a bad length), the atmel-sha and ccree drivers can set it if a memory allocation fails, and the chelsio driver sets it for bad auth tag lengths, not just bad key lengths. So even if someone actually wanted to start checking this flag (which seems unlikely, since it's been unused for a long time), there would be a lot of work needed to get it working correctly. But it would probably be much better to go back to the drawing board and just define different return values, like -EINVAL if the key is invalid for the algorithm vs. -EKEYREJECTED if the key was rejected by a policy like "no weak keys". That would be much simpler, less error-prone, and easier to test. So just remove this flag. Signed-off-by: Eric Biggers <ebiggers@google.com> Reviewed-by: Horia Geantă <horia.geanta@nxp.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
154 lines
3.7 KiB
C
154 lines
3.7 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 <asm/unaligned.h>
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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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/** 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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return -EINVAL;
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*mctx = get_unaligned_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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put_unaligned_le32(crc32_le(*crcp, data, len), out);
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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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put_unaligned_le32(*crcp, out);
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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-generic",
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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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subsys_initcall(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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MODULE_ALIAS_CRYPTO("crc32-generic");
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