xref: /linux/arch/riscv/crypto/chacha-riscv64-glue.c (revision 42d37fc0c819b81f6f6afd108b55d04ba9d32d0f)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * ChaCha20 using the RISC-V vector crypto extensions
4  *
5  * Copyright (C) 2023 SiFive, Inc.
6  * Author: Jerry Shih <jerry.shih@sifive.com>
7  */
8 
9 #include <asm/simd.h>
10 #include <asm/vector.h>
11 #include <crypto/internal/chacha.h>
12 #include <crypto/internal/skcipher.h>
13 #include <linux/linkage.h>
14 #include <linux/module.h>
15 
16 asmlinkage void chacha20_zvkb(const u32 key[8], const u8 *in, u8 *out,
17 			      size_t len, const u32 iv[4]);
18 
19 static int riscv64_chacha20_crypt(struct skcipher_request *req)
20 {
21 	u32 iv[CHACHA_IV_SIZE / sizeof(u32)];
22 	u8 block_buffer[CHACHA_BLOCK_SIZE];
23 	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
24 	const struct chacha_ctx *ctx = crypto_skcipher_ctx(tfm);
25 	struct skcipher_walk walk;
26 	unsigned int nbytes;
27 	unsigned int tail_bytes;
28 	int err;
29 
30 	iv[0] = get_unaligned_le32(req->iv);
31 	iv[1] = get_unaligned_le32(req->iv + 4);
32 	iv[2] = get_unaligned_le32(req->iv + 8);
33 	iv[3] = get_unaligned_le32(req->iv + 12);
34 
35 	err = skcipher_walk_virt(&walk, req, false);
36 	while (walk.nbytes) {
37 		nbytes = walk.nbytes & ~(CHACHA_BLOCK_SIZE - 1);
38 		tail_bytes = walk.nbytes & (CHACHA_BLOCK_SIZE - 1);
39 		kernel_vector_begin();
40 		if (nbytes) {
41 			chacha20_zvkb(ctx->key, walk.src.virt.addr,
42 				      walk.dst.virt.addr, nbytes, iv);
43 			iv[0] += nbytes / CHACHA_BLOCK_SIZE;
44 		}
45 		if (walk.nbytes == walk.total && tail_bytes > 0) {
46 			memcpy(block_buffer, walk.src.virt.addr + nbytes,
47 			       tail_bytes);
48 			chacha20_zvkb(ctx->key, block_buffer, block_buffer,
49 				      CHACHA_BLOCK_SIZE, iv);
50 			memcpy(walk.dst.virt.addr + nbytes, block_buffer,
51 			       tail_bytes);
52 			tail_bytes = 0;
53 		}
54 		kernel_vector_end();
55 
56 		err = skcipher_walk_done(&walk, tail_bytes);
57 	}
58 
59 	return err;
60 }
61 
62 static struct skcipher_alg riscv64_chacha_alg = {
63 	.setkey = chacha20_setkey,
64 	.encrypt = riscv64_chacha20_crypt,
65 	.decrypt = riscv64_chacha20_crypt,
66 	.min_keysize = CHACHA_KEY_SIZE,
67 	.max_keysize = CHACHA_KEY_SIZE,
68 	.ivsize = CHACHA_IV_SIZE,
69 	.chunksize = CHACHA_BLOCK_SIZE,
70 	.walksize = 4 * CHACHA_BLOCK_SIZE,
71 	.base = {
72 		.cra_blocksize = 1,
73 		.cra_ctxsize = sizeof(struct chacha_ctx),
74 		.cra_priority = 300,
75 		.cra_name = "chacha20",
76 		.cra_driver_name = "chacha20-riscv64-zvkb",
77 		.cra_module = THIS_MODULE,
78 	},
79 };
80 
81 static int __init riscv64_chacha_mod_init(void)
82 {
83 	if (riscv_isa_extension_available(NULL, ZVKB) &&
84 	    riscv_vector_vlen() >= 128)
85 		return crypto_register_skcipher(&riscv64_chacha_alg);
86 
87 	return -ENODEV;
88 }
89 
90 static void __exit riscv64_chacha_mod_exit(void)
91 {
92 	crypto_unregister_skcipher(&riscv64_chacha_alg);
93 }
94 
95 module_init(riscv64_chacha_mod_init);
96 module_exit(riscv64_chacha_mod_exit);
97 
98 MODULE_DESCRIPTION("ChaCha20 (RISC-V accelerated)");
99 MODULE_AUTHOR("Jerry Shih <jerry.shih@sifive.com>");
100 MODULE_LICENSE("GPL");
101 MODULE_ALIAS_CRYPTO("chacha20");
102