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