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-rw-r--r--crypto/crc32c_generic.c168
1 files changed, 168 insertions, 0 deletions
diff --git a/crypto/crc32c_generic.c b/crypto/crc32c_generic.c
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+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Cryptographic API.
+ *
+ * CRC32C chksum
+ *
+ *@Article{castagnoli-crc,
+ * author = { Guy Castagnoli and Stefan Braeuer and Martin Herrman},
+ * title = {{Optimization of Cyclic Redundancy-Check Codes with 24
+ * and 32 Parity Bits}},
+ * journal = IEEE Transactions on Communication,
+ * year = {1993},
+ * volume = {41},
+ * number = {6},
+ * pages = {},
+ * month = {June},
+ *}
+ * Used by the iSCSI driver, possibly others, and derived from
+ * the iscsi-crc.c module of the linux-iscsi driver at
+ * http://linux-iscsi.sourceforge.net.
+ *
+ * Following the example of lib/crc32, this function is intended to be
+ * flexible and useful for all users. Modules that currently have their
+ * own crc32c, but hopefully may be able to use this one are:
+ * net/sctp (please add all your doco to here if you change to
+ * use this one!)
+ * <endoflist>
+ *
+ * Copyright (c) 2004 Cisco Systems, Inc.
+ * Copyright (c) 2008 Herbert Xu <herbert@gondor.apana.org.au>
+ */
+
+#include <asm/unaligned.h>
+#include <crypto/internal/hash.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/string.h>
+#include <linux/kernel.h>
+#include <linux/crc32.h>
+
+#define CHKSUM_BLOCK_SIZE 1
+#define CHKSUM_DIGEST_SIZE 4
+
+struct chksum_ctx {
+ u32 key;
+};
+
+struct chksum_desc_ctx {
+ u32 crc;
+};
+
+/*
+ * Steps through buffer one byte at a time, calculates reflected
+ * crc using table.
+ */
+
+static int chksum_init(struct shash_desc *desc)
+{
+ struct chksum_ctx *mctx = crypto_shash_ctx(desc->tfm);
+ struct chksum_desc_ctx *ctx = shash_desc_ctx(desc);
+
+ ctx->crc = mctx->key;
+
+ return 0;
+}
+
+/*
+ * Setting the seed allows arbitrary accumulators and flexible XOR policy
+ * If your algorithm starts with ~0, then XOR with ~0 before you set
+ * the seed.
+ */
+static int chksum_setkey(struct crypto_shash *tfm, const u8 *key,
+ unsigned int keylen)
+{
+ struct chksum_ctx *mctx = crypto_shash_ctx(tfm);
+
+ if (keylen != sizeof(mctx->key))
+ return -EINVAL;
+ mctx->key = get_unaligned_le32(key);
+ return 0;
+}
+
+static int chksum_update(struct shash_desc *desc, const u8 *data,
+ unsigned int length)
+{
+ struct chksum_desc_ctx *ctx = shash_desc_ctx(desc);
+
+ ctx->crc = __crc32c_le(ctx->crc, data, length);
+ return 0;
+}
+
+static int chksum_final(struct shash_desc *desc, u8 *out)
+{
+ struct chksum_desc_ctx *ctx = shash_desc_ctx(desc);
+
+ put_unaligned_le32(~ctx->crc, out);
+ return 0;
+}
+
+static int __chksum_finup(u32 *crcp, const u8 *data, unsigned int len, u8 *out)
+{
+ put_unaligned_le32(~__crc32c_le(*crcp, data, len), out);
+ return 0;
+}
+
+static int chksum_finup(struct shash_desc *desc, const u8 *data,
+ unsigned int len, u8 *out)
+{
+ struct chksum_desc_ctx *ctx = shash_desc_ctx(desc);
+
+ return __chksum_finup(&ctx->crc, data, len, out);
+}
+
+static int chksum_digest(struct shash_desc *desc, const u8 *data,
+ unsigned int length, u8 *out)
+{
+ struct chksum_ctx *mctx = crypto_shash_ctx(desc->tfm);
+
+ return __chksum_finup(&mctx->key, data, length, out);
+}
+
+static int crc32c_cra_init(struct crypto_tfm *tfm)
+{
+ struct chksum_ctx *mctx = crypto_tfm_ctx(tfm);
+
+ mctx->key = ~0;
+ return 0;
+}
+
+static struct shash_alg alg = {
+ .digestsize = CHKSUM_DIGEST_SIZE,
+ .setkey = chksum_setkey,
+ .init = chksum_init,
+ .update = chksum_update,
+ .final = chksum_final,
+ .finup = chksum_finup,
+ .digest = chksum_digest,
+ .descsize = sizeof(struct chksum_desc_ctx),
+ .base = {
+ .cra_name = "crc32c",
+ .cra_driver_name = "crc32c-generic",
+ .cra_priority = 100,
+ .cra_flags = CRYPTO_ALG_OPTIONAL_KEY,
+ .cra_blocksize = CHKSUM_BLOCK_SIZE,
+ .cra_ctxsize = sizeof(struct chksum_ctx),
+ .cra_module = THIS_MODULE,
+ .cra_init = crc32c_cra_init,
+ }
+};
+
+static int __init crc32c_mod_init(void)
+{
+ return crypto_register_shash(&alg);
+}
+
+static void __exit crc32c_mod_fini(void)
+{
+ crypto_unregister_shash(&alg);
+}
+
+subsys_initcall(crc32c_mod_init);
+module_exit(crc32c_mod_fini);
+
+MODULE_AUTHOR("Clay Haapala <chaapala@cisco.com>");
+MODULE_DESCRIPTION("CRC32c (Castagnoli) calculations wrapper for lib/crc32c");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_CRYPTO("crc32c");
+MODULE_ALIAS_CRYPTO("crc32c-generic");