xref: /openbmc/linux/arch/s390/crypto/chacha-glue.c (revision 8703dd6b)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * s390 ChaCha stream cipher.
4  *
5  * Copyright IBM Corp. 2021
6  */
7 
8 #define KMSG_COMPONENT "chacha_s390"
9 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
10 
11 #include <crypto/internal/chacha.h>
12 #include <crypto/internal/skcipher.h>
13 #include <crypto/algapi.h>
14 #include <linux/cpufeature.h>
15 #include <linux/kernel.h>
16 #include <linux/module.h>
17 #include <linux/sizes.h>
18 #include <asm/fpu/api.h>
19 #include "chacha-s390.h"
20 
chacha20_crypt_s390(u32 * state,u8 * dst,const u8 * src,unsigned int nbytes,const u32 * key,u32 * counter)21 static void chacha20_crypt_s390(u32 *state, u8 *dst, const u8 *src,
22 				unsigned int nbytes, const u32 *key,
23 				u32 *counter)
24 {
25 	struct kernel_fpu vxstate;
26 
27 	kernel_fpu_begin(&vxstate, KERNEL_VXR);
28 	chacha20_vx(dst, src, nbytes, key, counter);
29 	kernel_fpu_end(&vxstate, KERNEL_VXR);
30 
31 	*counter += round_up(nbytes, CHACHA_BLOCK_SIZE) / CHACHA_BLOCK_SIZE;
32 }
33 
chacha20_s390(struct skcipher_request * req)34 static int chacha20_s390(struct skcipher_request *req)
35 {
36 	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
37 	struct chacha_ctx *ctx = crypto_skcipher_ctx(tfm);
38 	u32 state[CHACHA_STATE_WORDS] __aligned(16);
39 	struct skcipher_walk walk;
40 	unsigned int nbytes;
41 	int rc;
42 
43 	rc = skcipher_walk_virt(&walk, req, false);
44 	chacha_init_generic(state, ctx->key, req->iv);
45 
46 	while (walk.nbytes > 0) {
47 		nbytes = walk.nbytes;
48 		if (nbytes < walk.total)
49 			nbytes = round_down(nbytes, walk.stride);
50 
51 		if (nbytes <= CHACHA_BLOCK_SIZE) {
52 			chacha_crypt_generic(state, walk.dst.virt.addr,
53 					     walk.src.virt.addr, nbytes,
54 					     ctx->nrounds);
55 		} else {
56 			chacha20_crypt_s390(state, walk.dst.virt.addr,
57 					    walk.src.virt.addr, nbytes,
58 					    &state[4], &state[12]);
59 		}
60 		rc = skcipher_walk_done(&walk, walk.nbytes - nbytes);
61 	}
62 	return rc;
63 }
64 
hchacha_block_arch(const u32 * state,u32 * stream,int nrounds)65 void hchacha_block_arch(const u32 *state, u32 *stream, int nrounds)
66 {
67 	/* TODO: implement hchacha_block_arch() in assembly */
68 	hchacha_block_generic(state, stream, nrounds);
69 }
70 EXPORT_SYMBOL(hchacha_block_arch);
71 
chacha_init_arch(u32 * state,const u32 * key,const u8 * iv)72 void chacha_init_arch(u32 *state, const u32 *key, const u8 *iv)
73 {
74 	chacha_init_generic(state, key, iv);
75 }
76 EXPORT_SYMBOL(chacha_init_arch);
77 
chacha_crypt_arch(u32 * state,u8 * dst,const u8 * src,unsigned int bytes,int nrounds)78 void chacha_crypt_arch(u32 *state, u8 *dst, const u8 *src,
79 		       unsigned int bytes, int nrounds)
80 {
81 	/* s390 chacha20 implementation has 20 rounds hard-coded,
82 	 * it cannot handle a block of data or less, but otherwise
83 	 * it can handle data of arbitrary size
84 	 */
85 	if (bytes <= CHACHA_BLOCK_SIZE || nrounds != 20 || !MACHINE_HAS_VX)
86 		chacha_crypt_generic(state, dst, src, bytes, nrounds);
87 	else
88 		chacha20_crypt_s390(state, dst, src, bytes,
89 				    &state[4], &state[12]);
90 }
91 EXPORT_SYMBOL(chacha_crypt_arch);
92 
93 static struct skcipher_alg chacha_algs[] = {
94 	{
95 		.base.cra_name		= "chacha20",
96 		.base.cra_driver_name	= "chacha20-s390",
97 		.base.cra_priority	= 900,
98 		.base.cra_blocksize	= 1,
99 		.base.cra_ctxsize	= sizeof(struct chacha_ctx),
100 		.base.cra_module	= THIS_MODULE,
101 
102 		.min_keysize		= CHACHA_KEY_SIZE,
103 		.max_keysize		= CHACHA_KEY_SIZE,
104 		.ivsize			= CHACHA_IV_SIZE,
105 		.chunksize		= CHACHA_BLOCK_SIZE,
106 		.setkey			= chacha20_setkey,
107 		.encrypt		= chacha20_s390,
108 		.decrypt		= chacha20_s390,
109 	}
110 };
111 
chacha_mod_init(void)112 static int __init chacha_mod_init(void)
113 {
114 	return IS_REACHABLE(CONFIG_CRYPTO_SKCIPHER) ?
115 		crypto_register_skciphers(chacha_algs, ARRAY_SIZE(chacha_algs)) : 0;
116 }
117 
chacha_mod_fini(void)118 static void __exit chacha_mod_fini(void)
119 {
120 	if (IS_REACHABLE(CONFIG_CRYPTO_SKCIPHER))
121 		crypto_unregister_skciphers(chacha_algs, ARRAY_SIZE(chacha_algs));
122 }
123 
124 module_cpu_feature_match(S390_CPU_FEATURE_VXRS, chacha_mod_init);
125 module_exit(chacha_mod_fini);
126 
127 MODULE_DESCRIPTION("ChaCha20 stream cipher");
128 MODULE_LICENSE("GPL v2");
129 
130 MODULE_ALIAS_CRYPTO("chacha20");
131