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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>
168 lines
4.1 KiB
C
168 lines
4.1 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* Cryptographic API.
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*
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* CRC32C chksum
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*
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*@Article{castagnoli-crc,
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* author = { Guy Castagnoli and Stefan Braeuer and Martin Herrman},
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* title = {{Optimization of Cyclic Redundancy-Check Codes with 24
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* and 32 Parity Bits}},
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* journal = IEEE Transactions on Communication,
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* year = {1993},
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* volume = {41},
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* number = {6},
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* pages = {},
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* month = {June},
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*}
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* Used by the iSCSI driver, possibly others, and derived from the
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* the iscsi-crc.c module of the linux-iscsi driver at
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* http://linux-iscsi.sourceforge.net.
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*
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* Following the example of lib/crc32, this function is intended to be
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* flexible and useful for all users. Modules that currently have their
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* own crc32c, but hopefully may be able to use this one are:
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* net/sctp (please add all your doco to here if you change to
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* use this one!)
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* <endoflist>
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*
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* Copyright (c) 2004 Cisco Systems, Inc.
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* Copyright (c) 2008 Herbert Xu <herbert@gondor.apana.org.au>
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*/
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#include <asm/unaligned.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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#include <linux/crc32.h>
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#define CHKSUM_BLOCK_SIZE 1
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#define CHKSUM_DIGEST_SIZE 4
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struct chksum_ctx {
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u32 key;
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};
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struct chksum_desc_ctx {
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u32 crc;
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};
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/*
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* Steps through buffer one byte at at time, calculates reflected
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* crc using table.
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*/
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static int chksum_init(struct shash_desc *desc)
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{
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struct chksum_ctx *mctx = crypto_shash_ctx(desc->tfm);
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struct chksum_desc_ctx *ctx = shash_desc_ctx(desc);
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ctx->crc = mctx->key;
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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 chksum_setkey(struct crypto_shash *tfm, const u8 *key,
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unsigned int keylen)
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{
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struct chksum_ctx *mctx = crypto_shash_ctx(tfm);
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if (keylen != sizeof(mctx->key))
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return -EINVAL;
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mctx->key = get_unaligned_le32(key);
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return 0;
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}
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static int chksum_update(struct shash_desc *desc, const u8 *data,
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unsigned int length)
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{
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struct chksum_desc_ctx *ctx = shash_desc_ctx(desc);
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ctx->crc = __crc32c_le(ctx->crc, data, length);
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return 0;
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}
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static int chksum_final(struct shash_desc *desc, u8 *out)
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{
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struct chksum_desc_ctx *ctx = shash_desc_ctx(desc);
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put_unaligned_le32(~ctx->crc, out);
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return 0;
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}
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static int __chksum_finup(u32 *crcp, const u8 *data, unsigned int len, u8 *out)
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{
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put_unaligned_le32(~__crc32c_le(*crcp, data, len), out);
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return 0;
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}
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static int chksum_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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struct chksum_desc_ctx *ctx = shash_desc_ctx(desc);
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return __chksum_finup(&ctx->crc, data, len, out);
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}
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static int chksum_digest(struct shash_desc *desc, const u8 *data,
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unsigned int length, u8 *out)
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{
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struct chksum_ctx *mctx = crypto_shash_ctx(desc->tfm);
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return __chksum_finup(&mctx->key, data, length, out);
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}
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static int crc32c_cra_init(struct crypto_tfm *tfm)
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{
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struct chksum_ctx *mctx = crypto_tfm_ctx(tfm);
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mctx->key = ~0;
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return 0;
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}
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static struct shash_alg alg = {
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.digestsize = CHKSUM_DIGEST_SIZE,
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.setkey = chksum_setkey,
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.init = chksum_init,
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.update = chksum_update,
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.final = chksum_final,
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.finup = chksum_finup,
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.digest = chksum_digest,
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.descsize = sizeof(struct chksum_desc_ctx),
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.base = {
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.cra_name = "crc32c",
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.cra_driver_name = "crc32c-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(struct chksum_ctx),
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.cra_module = THIS_MODULE,
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.cra_init = crc32c_cra_init,
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}
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};
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static int __init crc32c_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 crc32c_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(crc32c_mod_init);
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module_exit(crc32c_mod_fini);
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MODULE_AUTHOR("Clay Haapala <chaapala@cisco.com>");
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MODULE_DESCRIPTION("CRC32c (Castagnoli) calculations wrapper for lib/crc32c");
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MODULE_LICENSE("GPL");
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MODULE_ALIAS_CRYPTO("crc32c");
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MODULE_ALIAS_CRYPTO("crc32c-generic");
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