arch/x86/crypto/poly1305_glue.c

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