xref: /openbmc/linux/arch/x86/crypto/poly1305_glue.c (revision 8d195e7a)
1 // SPDX-License-Identifier: GPL-2.0 OR MIT
2 /*
3  * Copyright (C) 2015-2019 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
4  */
5 
6 #include <crypto/algapi.h>
7 #include <crypto/internal/hash.h>
8 #include <crypto/internal/poly1305.h>
9 #include <crypto/internal/simd.h>
10 #include <linux/crypto.h>
11 #include <linux/jump_label.h>
12 #include <linux/kernel.h>
13 #include <linux/module.h>
14 #include <linux/sizes.h>
15 #include <asm/intel-family.h>
16 #include <asm/simd.h>
17 
18 asmlinkage void poly1305_init_x86_64(void *ctx,
19 				     const u8 key[POLY1305_BLOCK_SIZE]);
20 asmlinkage void poly1305_blocks_x86_64(void *ctx, const u8 *inp,
21 				       const size_t len, const u32 padbit);
22 asmlinkage void poly1305_emit_x86_64(void *ctx, u8 mac[POLY1305_DIGEST_SIZE],
23 				     const u32 nonce[4]);
24 asmlinkage void poly1305_emit_avx(void *ctx, u8 mac[POLY1305_DIGEST_SIZE],
25 				  const u32 nonce[4]);
26 asmlinkage void poly1305_blocks_avx(void *ctx, const u8 *inp, const size_t len,
27 				    const u32 padbit);
28 asmlinkage void poly1305_blocks_avx2(void *ctx, const u8 *inp, const size_t len,
29 				     const u32 padbit);
30 asmlinkage void poly1305_blocks_avx512(void *ctx, const u8 *inp,
31 				       const size_t len, const u32 padbit);
32 
33 static __ro_after_init DEFINE_STATIC_KEY_FALSE(poly1305_use_avx);
34 static __ro_after_init DEFINE_STATIC_KEY_FALSE(poly1305_use_avx2);
35 static __ro_after_init DEFINE_STATIC_KEY_FALSE(poly1305_use_avx512);
36 
37 struct poly1305_arch_internal {
38 	union {
39 		struct {
40 			u32 h[5];
41 			u32 is_base2_26;
42 		};
43 		u64 hs[3];
44 	};
45 	u64 r[2];
46 	u64 pad;
47 	struct { u32 r2, r1, r4, r3; } rn[9];
48 };
49 
50 /* The AVX code uses base 2^26, while the scalar code uses base 2^64. If we hit
51  * the unfortunate situation of using AVX and then having to go back to scalar
52  * -- because the user is silly and has called the update function from two
53  * separate contexts -- then we need to convert back to the original base before
54  * proceeding. It is possible to reason that the initial reduction below is
55  * sufficient given the implementation invariants. However, for an avoidance of
56  * doubt and because this is not performance critical, we do the full reduction
57  * anyway. Z3 proof of below function: https://xn--4db.cc/ltPtHCKN/py
58  */
convert_to_base2_64(void * ctx)59 static void convert_to_base2_64(void *ctx)
60 {
61 	struct poly1305_arch_internal *state = ctx;
62 	u32 cy;
63 
64 	if (!state->is_base2_26)
65 		return;
66 
67 	cy = state->h[0] >> 26; state->h[0] &= 0x3ffffff; state->h[1] += cy;
68 	cy = state->h[1] >> 26; state->h[1] &= 0x3ffffff; state->h[2] += cy;
69 	cy = state->h[2] >> 26; state->h[2] &= 0x3ffffff; state->h[3] += cy;
70 	cy = state->h[3] >> 26; state->h[3] &= 0x3ffffff; state->h[4] += cy;
71 	state->hs[0] = ((u64)state->h[2] << 52) | ((u64)state->h[1] << 26) | state->h[0];
72 	state->hs[1] = ((u64)state->h[4] << 40) | ((u64)state->h[3] << 14) | (state->h[2] >> 12);
73 	state->hs[2] = state->h[4] >> 24;
74 #define ULT(a, b) ((a ^ ((a ^ b) | ((a - b) ^ b))) >> (sizeof(a) * 8 - 1))
75 	cy = (state->hs[2] >> 2) + (state->hs[2] & ~3ULL);
76 	state->hs[2] &= 3;
77 	state->hs[0] += cy;
78 	state->hs[1] += (cy = ULT(state->hs[0], cy));
79 	state->hs[2] += ULT(state->hs[1], cy);
80 #undef ULT
81 	state->is_base2_26 = 0;
82 }
83 
poly1305_simd_init(void * ctx,const u8 key[POLY1305_BLOCK_SIZE])84 static void poly1305_simd_init(void *ctx, const u8 key[POLY1305_BLOCK_SIZE])
85 {
86 	poly1305_init_x86_64(ctx, key);
87 }
88 
poly1305_simd_blocks(void * ctx,const u8 * inp,size_t len,const u32 padbit)89 static void poly1305_simd_blocks(void *ctx, const u8 *inp, size_t len,
90 				 const u32 padbit)
91 {
92 	struct poly1305_arch_internal *state = ctx;
93 
94 	/* SIMD disables preemption, so relax after processing each page. */
95 	BUILD_BUG_ON(SZ_4K < POLY1305_BLOCK_SIZE ||
96 		     SZ_4K % POLY1305_BLOCK_SIZE);
97 
98 	if (!static_branch_likely(&poly1305_use_avx) ||
99 	    (len < (POLY1305_BLOCK_SIZE * 18) && !state->is_base2_26) ||
100 	    !crypto_simd_usable()) {
101 		convert_to_base2_64(ctx);
102 		poly1305_blocks_x86_64(ctx, inp, len, padbit);
103 		return;
104 	}
105 
106 	do {
107 		const size_t bytes = min_t(size_t, len, SZ_4K);
108 
109 		kernel_fpu_begin();
110 		if (IS_ENABLED(CONFIG_AS_AVX512) && static_branch_likely(&poly1305_use_avx512))
111 			poly1305_blocks_avx512(ctx, inp, bytes, padbit);
112 		else if (static_branch_likely(&poly1305_use_avx2))
113 			poly1305_blocks_avx2(ctx, inp, bytes, padbit);
114 		else
115 			poly1305_blocks_avx(ctx, inp, bytes, padbit);
116 		kernel_fpu_end();
117 
118 		len -= bytes;
119 		inp += bytes;
120 	} while (len);
121 }
122 
poly1305_simd_emit(void * ctx,u8 mac[POLY1305_DIGEST_SIZE],const u32 nonce[4])123 static void poly1305_simd_emit(void *ctx, u8 mac[POLY1305_DIGEST_SIZE],
124 			       const u32 nonce[4])
125 {
126 	if (!static_branch_likely(&poly1305_use_avx))
127 		poly1305_emit_x86_64(ctx, mac, nonce);
128 	else
129 		poly1305_emit_avx(ctx, mac, nonce);
130 }
131 
poly1305_init_arch(struct poly1305_desc_ctx * dctx,const u8 key[POLY1305_KEY_SIZE])132 void poly1305_init_arch(struct poly1305_desc_ctx *dctx, const u8 key[POLY1305_KEY_SIZE])
133 {
134 	poly1305_simd_init(&dctx->h, key);
135 	dctx->s[0] = get_unaligned_le32(&key[16]);
136 	dctx->s[1] = get_unaligned_le32(&key[20]);
137 	dctx->s[2] = get_unaligned_le32(&key[24]);
138 	dctx->s[3] = get_unaligned_le32(&key[28]);
139 	dctx->buflen = 0;
140 	dctx->sset = true;
141 }
142 EXPORT_SYMBOL(poly1305_init_arch);
143 
crypto_poly1305_setdctxkey(struct poly1305_desc_ctx * dctx,const u8 * inp,unsigned int len)144 static unsigned int crypto_poly1305_setdctxkey(struct poly1305_desc_ctx *dctx,
145 					       const u8 *inp, unsigned int len)
146 {
147 	unsigned int acc = 0;
148 	if (unlikely(!dctx->sset)) {
149 		if (!dctx->rset && len >= POLY1305_BLOCK_SIZE) {
150 			poly1305_simd_init(&dctx->h, inp);
151 			inp += POLY1305_BLOCK_SIZE;
152 			len -= POLY1305_BLOCK_SIZE;
153 			acc += POLY1305_BLOCK_SIZE;
154 			dctx->rset = 1;
155 		}
156 		if (len >= POLY1305_BLOCK_SIZE) {
157 			dctx->s[0] = get_unaligned_le32(&inp[0]);
158 			dctx->s[1] = get_unaligned_le32(&inp[4]);
159 			dctx->s[2] = get_unaligned_le32(&inp[8]);
160 			dctx->s[3] = get_unaligned_le32(&inp[12]);
161 			acc += POLY1305_BLOCK_SIZE;
162 			dctx->sset = true;
163 		}
164 	}
165 	return acc;
166 }
167 
poly1305_update_arch(struct poly1305_desc_ctx * dctx,const u8 * src,unsigned int srclen)168 void poly1305_update_arch(struct poly1305_desc_ctx *dctx, const u8 *src,
169 			  unsigned int srclen)
170 {
171 	unsigned int bytes, used;
172 
173 	if (unlikely(dctx->buflen)) {
174 		bytes = min(srclen, POLY1305_BLOCK_SIZE - dctx->buflen);
175 		memcpy(dctx->buf + dctx->buflen, src, bytes);
176 		src += bytes;
177 		srclen -= bytes;
178 		dctx->buflen += bytes;
179 
180 		if (dctx->buflen == POLY1305_BLOCK_SIZE) {
181 			if (likely(!crypto_poly1305_setdctxkey(dctx, dctx->buf, POLY1305_BLOCK_SIZE)))
182 				poly1305_simd_blocks(&dctx->h, dctx->buf, POLY1305_BLOCK_SIZE, 1);
183 			dctx->buflen = 0;
184 		}
185 	}
186 
187 	if (likely(srclen >= POLY1305_BLOCK_SIZE)) {
188 		bytes = round_down(srclen, POLY1305_BLOCK_SIZE);
189 		srclen -= bytes;
190 		used = crypto_poly1305_setdctxkey(dctx, src, bytes);
191 		if (likely(bytes - used))
192 			poly1305_simd_blocks(&dctx->h, src + used, bytes - used, 1);
193 		src += bytes;
194 	}
195 
196 	if (unlikely(srclen)) {
197 		dctx->buflen = srclen;
198 		memcpy(dctx->buf, src, srclen);
199 	}
200 }
201 EXPORT_SYMBOL(poly1305_update_arch);
202 
poly1305_final_arch(struct poly1305_desc_ctx * dctx,u8 * dst)203 void poly1305_final_arch(struct poly1305_desc_ctx *dctx, u8 *dst)
204 {
205 	if (unlikely(dctx->buflen)) {
206 		dctx->buf[dctx->buflen++] = 1;
207 		memset(dctx->buf + dctx->buflen, 0,
208 		       POLY1305_BLOCK_SIZE - dctx->buflen);
209 		poly1305_simd_blocks(&dctx->h, dctx->buf, POLY1305_BLOCK_SIZE, 0);
210 	}
211 
212 	poly1305_simd_emit(&dctx->h, dst, dctx->s);
213 	memzero_explicit(dctx, sizeof(*dctx));
214 }
215 EXPORT_SYMBOL(poly1305_final_arch);
216 
crypto_poly1305_init(struct shash_desc * desc)217 static int crypto_poly1305_init(struct shash_desc *desc)
218 {
219 	struct poly1305_desc_ctx *dctx = shash_desc_ctx(desc);
220 
221 	*dctx = (struct poly1305_desc_ctx){};
222 	return 0;
223 }
224 
crypto_poly1305_update(struct shash_desc * desc,const u8 * src,unsigned int srclen)225 static int crypto_poly1305_update(struct shash_desc *desc,
226 				  const u8 *src, unsigned int srclen)
227 {
228 	struct poly1305_desc_ctx *dctx = shash_desc_ctx(desc);
229 
230 	poly1305_update_arch(dctx, src, srclen);
231 	return 0;
232 }
233 
crypto_poly1305_final(struct shash_desc * desc,u8 * dst)234 static int crypto_poly1305_final(struct shash_desc *desc, u8 *dst)
235 {
236 	struct poly1305_desc_ctx *dctx = shash_desc_ctx(desc);
237 
238 	if (unlikely(!dctx->sset))
239 		return -ENOKEY;
240 
241 	poly1305_final_arch(dctx, dst);
242 	return 0;
243 }
244 
245 static struct shash_alg alg = {
246 	.digestsize	= POLY1305_DIGEST_SIZE,
247 	.init		= crypto_poly1305_init,
248 	.update		= crypto_poly1305_update,
249 	.final		= crypto_poly1305_final,
250 	.descsize	= sizeof(struct poly1305_desc_ctx),
251 	.base		= {
252 		.cra_name		= "poly1305",
253 		.cra_driver_name	= "poly1305-simd",
254 		.cra_priority		= 300,
255 		.cra_blocksize		= POLY1305_BLOCK_SIZE,
256 		.cra_module		= THIS_MODULE,
257 	},
258 };
259 
poly1305_simd_mod_init(void)260 static int __init poly1305_simd_mod_init(void)
261 {
262 	if (boot_cpu_has(X86_FEATURE_AVX) &&
263 	    cpu_has_xfeatures(XFEATURE_MASK_SSE | XFEATURE_MASK_YMM, NULL))
264 		static_branch_enable(&poly1305_use_avx);
265 	if (boot_cpu_has(X86_FEATURE_AVX) && boot_cpu_has(X86_FEATURE_AVX2) &&
266 	    cpu_has_xfeatures(XFEATURE_MASK_SSE | XFEATURE_MASK_YMM, NULL))
267 		static_branch_enable(&poly1305_use_avx2);
268 	if (IS_ENABLED(CONFIG_AS_AVX512) && boot_cpu_has(X86_FEATURE_AVX) &&
269 	    boot_cpu_has(X86_FEATURE_AVX2) && boot_cpu_has(X86_FEATURE_AVX512F) &&
270 	    cpu_has_xfeatures(XFEATURE_MASK_SSE | XFEATURE_MASK_YMM | XFEATURE_MASK_AVX512, NULL) &&
271 	    /* Skylake downclocks unacceptably much when using zmm, but later generations are fast. */
272 	    boot_cpu_data.x86_model != INTEL_FAM6_SKYLAKE_X)
273 		static_branch_enable(&poly1305_use_avx512);
274 	return IS_REACHABLE(CONFIG_CRYPTO_HASH) ? crypto_register_shash(&alg) : 0;
275 }
276 
poly1305_simd_mod_exit(void)277 static void __exit poly1305_simd_mod_exit(void)
278 {
279 	if (IS_REACHABLE(CONFIG_CRYPTO_HASH))
280 		crypto_unregister_shash(&alg);
281 }
282 
283 module_init(poly1305_simd_mod_init);
284 module_exit(poly1305_simd_mod_exit);
285 
286 MODULE_LICENSE("GPL");
287 MODULE_AUTHOR("Jason A. Donenfeld <Jason@zx2c4.com>");
288 MODULE_DESCRIPTION("Poly1305 authenticator");
289 MODULE_ALIAS_CRYPTO("poly1305");
290 MODULE_ALIAS_CRYPTO("poly1305-simd");
291