src/boot/efi/sha256.c

   1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
   2
   3 /* Stolen from glibc and converted to UEFI style. In glibc it comes with the following copyright blurb: */
   4
   5 /* Functions to compute SHA256 message digest of files or memory blocks.
   6    according to the definition of SHA256 in FIPS 180-2.
   7    Copyright (C) 2007-2019 Free Software Foundation, Inc.
   8    This file is part of the GNU C Library.
   9
  10    The GNU C Library is free software; you can redistribute it and/or
  11    modify it under the terms of the GNU Lesser General Public
  12    License as published by the Free Software Foundation; either
  13    version 2.1 of the License, or (at your option) any later version.
  14
  15    The GNU C Library is distributed in the hope that it will be useful,
  16    but WITHOUT ANY WARRANTY; without even the implied warranty of
  17    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  18    Lesser General Public License for more details.
  19
  20    You should have received a copy of the GNU Lesser General Public
  21    License along with the GNU C Library; if not, see
  22    <http://www.gnu.org/licenses/>.  */
  23
  24 /* Written by Ulrich Drepper <drepper@redhat.com>, 2007.  */
  25
  26 #include "sha256.h"
  27
  28 #if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
  29 # define SWAP(n)                                                        \
  30         (((n) << 24) | (((n) & 0xff00) << 8) | (((n) >> 8) & 0xff00) | ((n) >> 24))
  31 # define SWAP64(n)                              \
  32         (((n) << 56)                            \
  33          | (((n) & 0xff00) << 40)               \
  34          | (((n) & 0xff0000) << 24)             \
  35          | (((n) & 0xff000000) << 8)            \
  36          | (((n) >> 8) & 0xff000000)            \
  37          | (((n) >> 24) & 0xff0000)             \
  38          | (((n) >> 40) & 0xff00)               \
  39          | ((n) >> 56))
  40 #else
  41 # define SWAP(n) (n)
  42 # define SWAP64(n) (n)
  43 #endif
  44
  45 /* This array contains the bytes used to pad the buffer to the next
  46    64-byte boundary.  (FIPS 180-2:5.1.1)  */
  47 static const UINT8 fillbuf[64] = {
  48         0x80, 0 /* , 0, 0, ...  */
  49 };
  50
  51 /* Constants for SHA256 from FIPS 180-2:4.2.2.  */
  52 static const UINT32 K[64] = {
  53         0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5,
  54         0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
  55         0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3,
  56         0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
  57         0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc,
  58         0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
  59         0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7,
  60         0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
  61         0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13,
  62         0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
  63         0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3,
  64         0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
  65         0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5,
  66         0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
  67         0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208,
  68         0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2
  69 };
  70
  71 static void sha256_process_block(const void *, UINTN, struct sha256_ctx *);
  72
  73 /* Initialize structure containing state of computation.
  74    (FIPS 180-2:5.3.2)  */
  75 void sha256_init_ctx(struct sha256_ctx *ctx) {
  76         ctx->H[0] = 0x6a09e667;
  77         ctx->H[1] = 0xbb67ae85;
  78         ctx->H[2] = 0x3c6ef372;
  79         ctx->H[3] = 0xa54ff53a;
  80         ctx->H[4] = 0x510e527f;
  81         ctx->H[5] = 0x9b05688c;
  82         ctx->H[6] = 0x1f83d9ab;
  83         ctx->H[7] = 0x5be0cd19;
  84
  85         ctx->total64 = 0;
  86         ctx->buflen = 0;
  87 }
  88
  89 /* Process the remaining bytes in the internal buffer and the usual
  90    prolog according to the standard and write the result to RESBUF.
  91
  92    IMPORTANT: On some systems it is required that RESBUF is correctly
  93    aligned for a 32 bits value.  */
  94 void *sha256_finish_ctx(struct sha256_ctx *ctx, void *resbuf) {
  95         /* Take yet unprocessed bytes into account.  */
  96         UINT32 bytes = ctx->buflen;
  97         UINTN pad;
  98
  99         /* Now count remaining bytes.  */
 100         ctx->total64 += bytes;
 101
 102         pad = bytes >= 56 ? 64 + 56 - bytes : 56 - bytes;
 103         CopyMem (&ctx->buffer[bytes], fillbuf, pad);
 104
 105         /* Put the 64-bit file length in *bits* at the end of the buffer.  */
 106         ctx->buffer32[(bytes + pad + 4) / 4] = SWAP (ctx->total[TOTAL64_low] << 3);
 107         ctx->buffer32[(bytes + pad) / 4] = SWAP ((ctx->total[TOTAL64_high] << 3)
 108                                                  | (ctx->total[TOTAL64_low] >> 29));
 109
 110         /* Process last bytes.  */
 111         sha256_process_block (ctx->buffer, bytes + pad + 8, ctx);
 112
 113         /* Put result from CTX in first 32 bytes following RESBUF.  */
 114         for (UINTN i = 0; i < 8; ++i)
 115                 ((UINT32 *) resbuf)[i] = SWAP (ctx->H[i]);
 116
 117         return resbuf;
 118 }
 119
 120 void sha256_process_bytes(const void *buffer, UINTN len, struct sha256_ctx *ctx) {
 121         /* When we already have some bits in our internal buffer concatenate
 122            both inputs first.  */
 123
 124         if (ctx->buflen != 0) {
 125                 UINTN left_over = ctx->buflen;
 126                 UINTN add = 128 - left_over > len ? len : 128 - left_over;
 127
 128                 CopyMem (&ctx->buffer[left_over], buffer, add);
 129                 ctx->buflen += add;
 130
 131                 if (ctx->buflen > 64) {
 132                         sha256_process_block (ctx->buffer, ctx->buflen & ~63, ctx);
 133
 134                         ctx->buflen &= 63;
 135                         /* The regions in the following copy operation cannot overlap.  */
 136                         CopyMem (ctx->buffer, &ctx->buffer[(left_over + add) & ~63],
 137                                 ctx->buflen);
 138                 }
 139
 140                 buffer = (const char *) buffer + add;
 141                 len -= add;
 142         }
 143
 144         /* Process available complete blocks.  */
 145         if (len >= 64) {
 146
 147 /* The condition below is from glibc's string/string-inline.c.
 148  * See definition of _STRING_INLINE_unaligned. */
 149 #if !defined(__mc68020__) && !defined(__s390__) && !defined(__i386__)
 150
 151 /* To check alignment gcc has an appropriate operator. Other compilers don't.  */
 152 # if __GNUC__ >= 2
 153 #  define UNALIGNED_P(p) (((UINTN) p) % __alignof__ (UINT32) != 0)
 154 # else
 155 #  define UNALIGNED_P(p) (((UINTN) p) % sizeof (UINT32) != 0)
 156 # endif
 157                 if (UNALIGNED_P (buffer))
 158                         while (len > 64) {
 159                                 CopyMem (ctx->buffer, buffer, 64);
 160                                 sha256_process_block (ctx->buffer, 64, ctx);
 161                                 buffer = (const char *) buffer + 64;
 162                                 len -= 64;
 163                         }
 164                 else
 165 #endif
 166                 {
 167                         sha256_process_block (buffer, len & ~63, ctx);
 168                         buffer = (const char *) buffer + (len & ~63);
 169                         len &= 63;
 170                 }
 171         }
 172
 173         /* Move remaining bytes into internal buffer.  */
 174         if (len > 0) {
 175                 UINTN left_over = ctx->buflen;
 176
 177                 CopyMem (&ctx->buffer[left_over], buffer, len);
 178                 left_over += len;
 179                 if (left_over >= 64) {
 180                         sha256_process_block (ctx->buffer, 64, ctx);
 181                         left_over -= 64;
 182                         CopyMem (ctx->buffer, &ctx->buffer[64], left_over);
 183                 }
 184                 ctx->buflen = left_over;
 185         }
 186 }
 187
 188
 189 /* Process LEN bytes of BUFFER, accumulating context into CTX.
 190    It is assumed that LEN % 64 == 0.  */
 191 static void sha256_process_block(const void *buffer, UINTN len, struct sha256_ctx *ctx) {
 192         const UINT32 *words = buffer;
 193         UINTN nwords = len / sizeof (UINT32);
 194         UINT32 a = ctx->H[0];
 195         UINT32 b = ctx->H[1];
 196         UINT32 c = ctx->H[2];
 197         UINT32 d = ctx->H[3];
 198         UINT32 e = ctx->H[4];
 199         UINT32 f = ctx->H[5];
 200         UINT32 g = ctx->H[6];
 201         UINT32 h = ctx->H[7];
 202
 203         /* First increment the byte count.  FIPS 180-2 specifies the possible
 204            length of the file up to 2^64 bits.  Here we only compute the
 205            number of bytes.  */
 206         ctx->total64 += len;
 207
 208         /* Process all bytes in the buffer with 64 bytes in each round of
 209            the loop.  */
 210         while (nwords > 0) {
 211                 UINT32 W[64];
 212                 UINT32 a_save = a;
 213                 UINT32 b_save = b;
 214                 UINT32 c_save = c;
 215                 UINT32 d_save = d;
 216                 UINT32 e_save = e;
 217                 UINT32 f_save = f;
 218                 UINT32 g_save = g;
 219                 UINT32 h_save = h;
 220
 221                 /* Operators defined in FIPS 180-2:4.1.2.  */
 222 #define Ch(x, y, z) ((x & y) ^ (~x & z))
 223 #define Maj(x, y, z) ((x & y) ^ (x & z) ^ (y & z))
 224 #define S0(x) (CYCLIC (x, 2) ^ CYCLIC (x, 13) ^ CYCLIC (x, 22))
 225 #define S1(x) (CYCLIC (x, 6) ^ CYCLIC (x, 11) ^ CYCLIC (x, 25))
 226 #define R0(x) (CYCLIC (x, 7) ^ CYCLIC (x, 18) ^ (x >> 3))
 227 #define R1(x) (CYCLIC (x, 17) ^ CYCLIC (x, 19) ^ (x >> 10))
 228
 229                 /* It is unfortunate that C does not provide an operator for
 230                    cyclic rotation.  Hope the C compiler is smart enough.  */
 231 #define CYCLIC(w, s) ((w >> s) | (w << (32 - s)))
 232
 233                 /* Compute the message schedule according to FIPS 180-2:6.2.2 step 2.  */
 234                 for (UINTN t = 0; t < 16; ++t) {
 235                         W[t] = SWAP (*words);
 236                         ++words;
 237                 }
 238                 for (UINTN t = 16; t < 64; ++t)
 239                         W[t] = R1 (W[t - 2]) + W[t - 7] + R0 (W[t - 15]) + W[t - 16];
 240
 241                 /* The actual computation according to FIPS 180-2:6.2.2 step 3.  */
 242                 for (UINTN t = 0; t < 64; ++t) {
 243                         UINT32 T1 = h + S1 (e) + Ch (e, f, g) + K[t] + W[t];
 244                         UINT32 T2 = S0 (a) + Maj (a, b, c);
 245                         h = g;
 246                         g = f;
 247                         f = e;
 248                         e = d + T1;
 249                         d = c;
 250                         c = b;
 251                         b = a;
 252                         a = T1 + T2;
 253                 }
 254
 255                 /* Add the starting values of the context according to FIPS 180-2:6.2.2
 256                    step 4.  */
 257                 a += a_save;
 258                 b += b_save;
 259                 c += c_save;
 260                 d += d_save;
 261                 e += e_save;
 262                 f += f_save;
 263                 g += g_save;
 264                 h += h_save;
 265
 266                 /* Prepare for the next round.  */
 267                 nwords -= 16;
 268         }
 269
 270         /* Put checksum in context given as argument.  */
 271         ctx->H[0] = a;
 272         ctx->H[1] = b;
 273         ctx->H[2] = c;
 274         ctx->H[3] = d;
 275         ctx->H[4] = e;
 276         ctx->H[5] = f;
 277         ctx->H[6] = g;
 278         ctx->H[7] = h;
 279 }