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 <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_KEY_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  */
  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
  84 static void poly1305_simd_init(void *ctx, const u8 key[POLY1305_KEY_SIZE])
  85 {
  86         poly1305_init_x86_64(ctx, key);
  87 }
  88
  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
 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
 132 void poly1305_init_arch(struct poly1305_desc_ctx *dctx, const u8 *key)
 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
 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
 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
 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
 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
 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
 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
 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
 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");