/* SPDX-License-Identifier: LGPL-2.1-or-later */ /* Stolen from glibc and converted to our style. In glibc it comes with the following copyright blurb: */ /* Functions to compute SHA256 message digest of files or memory blocks. according to the definition of SHA256 in FIPS 180-2. Copyright (C) 2007-2022 Free Software Foundation, Inc. This file is part of the GNU C Library. The GNU C Library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. The GNU C Library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with the GNU C Library; if not, see <https://www.gnu.org/licenses/>. */ #include <stdbool.h> #if SD_BOOT # include "efi-string.h" #else # include <string.h> #endif #include "macro-fundamental.h" #include "sha256-fundamental.h" #include "unaligned-fundamental.h" #if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__ # define SWAP(n) \ __builtin_bswap32(n) # define SWAP64(n) \ __builtin_bswap64(n) #else # define SWAP(n) (n) # define SWAP64(n) (n) #endif /* This array contains the bytes used to pad the buffer to the next 64-byte boundary. (FIPS 180-2:5.1.1) */ static const uint8_t fillbuf[64] = { 0x80, 0 /* , 0, 0, ... */ }; /* Constants for SHA256 from FIPS 180-2:4.2.2. */ static const uint32_t K[64] = { 0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5, 0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5, 0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3, 0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174, 0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc, 0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da, 0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7, 0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967, 0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13, 0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85, 0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3, 0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070, 0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5, 0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3, 0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208, 0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2 }; static void sha256_process_block(const void *, size_t, struct sha256_ctx *); /* Initialize structure containing state of computation. (FIPS 180-2:5.3.2) */ void sha256_init_ctx(struct sha256_ctx *ctx) { assert(ctx); ctx->H[0] = 0x6a09e667; ctx->H[1] = 0xbb67ae85; ctx->H[2] = 0x3c6ef372; ctx->H[3] = 0xa54ff53a; ctx->H[4] = 0x510e527f; ctx->H[5] = 0x9b05688c; ctx->H[6] = 0x1f83d9ab; ctx->H[7] = 0x5be0cd19; ctx->total64 = 0; ctx->buflen = 0; } /* Process the remaining bytes in the internal buffer and the usual prolog according to the standard and write the result to RESBUF. */ uint8_t *sha256_finish_ctx(struct sha256_ctx *ctx, uint8_t resbuf[static SHA256_DIGEST_SIZE]) { /* Take yet unprocessed bytes into account. */ uint32_t bytes = ctx->buflen; size_t pad; assert(ctx); assert(resbuf); /* Now count remaining bytes. */ ctx->total64 += bytes; pad = bytes >= 56 ? 64 + 56 - bytes : 56 - bytes; memcpy(&ctx->buffer[bytes], fillbuf, pad); /* Put the 64-bit file length in *bits* at the end of the buffer. */ ctx->buffer32[(bytes + pad + 4) / 4] = SWAP(ctx->total[TOTAL64_low] << 3); ctx->buffer32[(bytes + pad) / 4] = SWAP((ctx->total[TOTAL64_high] << 3) | (ctx->total[TOTAL64_low] >> 29)); /* Process last bytes. */ sha256_process_block(ctx->buffer, bytes + pad + 8, ctx); /* Put result from CTX in first 32 bytes following RESBUF. */ for (size_t i = 0; i < 8; ++i) unaligned_write_ne32(resbuf + i * sizeof(uint32_t), SWAP(ctx->H[i])); return resbuf; } void sha256_process_bytes(const void *buffer, size_t len, struct sha256_ctx *ctx) { assert(buffer); assert(ctx); /* When we already have some bits in our internal buffer concatenate both inputs first. */ if (ctx->buflen != 0) { size_t left_over = ctx->buflen; size_t add = 128 - left_over > len ? len : 128 - left_over; memcpy(&ctx->buffer[left_over], buffer, add); ctx->buflen += add; if (ctx->buflen > 64) { sha256_process_block(ctx->buffer, ctx->buflen & ~63, ctx); ctx->buflen &= 63; /* The regions in the following copy operation cannot overlap. */ memcpy(ctx->buffer, &ctx->buffer[(left_over + add) & ~63], ctx->buflen); } buffer = (const char *) buffer + add; len -= add; } /* Process available complete blocks. */ if (len >= 64) { if (IS_ALIGNED32(buffer)) { sha256_process_block(buffer, len & ~63, ctx); buffer = (const char *) buffer + (len & ~63); len &= 63; } else while (len > 64) { memcpy(ctx->buffer, buffer, 64); sha256_process_block(ctx->buffer, 64, ctx); buffer = (const char *) buffer + 64; len -= 64; } } /* Move remaining bytes into internal buffer. */ if (len > 0) { size_t left_over = ctx->buflen; memcpy(&ctx->buffer[left_over], buffer, len); left_over += len; if (left_over >= 64) { sha256_process_block(ctx->buffer, 64, ctx); left_over -= 64; memcpy(ctx->buffer, &ctx->buffer[64], left_over); } ctx->buflen = left_over; } } /* Process LEN bytes of BUFFER, accumulating context into CTX. It is assumed that LEN % 64 == 0. */ static void sha256_process_block(const void *buffer, size_t len, struct sha256_ctx *ctx) { const uint32_t *words = ASSERT_PTR(buffer); size_t nwords = len / sizeof(uint32_t); assert(ctx); uint32_t a = ctx->H[0]; uint32_t b = ctx->H[1]; uint32_t c = ctx->H[2]; uint32_t d = ctx->H[3]; uint32_t e = ctx->H[4]; uint32_t f = ctx->H[5]; uint32_t g = ctx->H[6]; uint32_t h = ctx->H[7]; /* First increment the byte count. FIPS 180-2 specifies the possible length of the file up to 2^64 bits. Here we only compute the number of bytes. */ ctx->total64 += len; /* Process all bytes in the buffer with 64 bytes in each round of the loop. */ while (nwords > 0) { uint32_t W[64]; uint32_t a_save = a; uint32_t b_save = b; uint32_t c_save = c; uint32_t d_save = d; uint32_t e_save = e; uint32_t f_save = f; uint32_t g_save = g; uint32_t h_save = h; /* Operators defined in FIPS 180-2:4.1.2. */ #define Ch(x, y, z) ((x & y) ^ (~x & z)) #define Maj(x, y, z) ((x & y) ^ (x & z) ^ (y & z)) #define S0(x) (CYCLIC (x, 2) ^ CYCLIC (x, 13) ^ CYCLIC (x, 22)) #define S1(x) (CYCLIC (x, 6) ^ CYCLIC (x, 11) ^ CYCLIC (x, 25)) #define R0(x) (CYCLIC (x, 7) ^ CYCLIC (x, 18) ^ (x >> 3)) #define R1(x) (CYCLIC (x, 17) ^ CYCLIC (x, 19) ^ (x >> 10)) /* It is unfortunate that C does not provide an operator for cyclic rotation. Hope the C compiler is smart enough. */ #define CYCLIC(w, s) ((w >> s) | (w << (32 - s))) /* Compute the message schedule according to FIPS 180-2:6.2.2 step 2. */ for (size_t t = 0; t < 16; ++t) { W[t] = SWAP (*words); ++words; } for (size_t t = 16; t < 64; ++t) W[t] = R1 (W[t - 2]) + W[t - 7] + R0 (W[t - 15]) + W[t - 16]; /* The actual computation according to FIPS 180-2:6.2.2 step 3. */ for (size_t t = 0; t < 64; ++t) { uint32_t T1 = h + S1 (e) + Ch (e, f, g) + K[t] + W[t]; uint32_t T2 = S0 (a) + Maj (a, b, c); h = g; g = f; f = e; e = d + T1; d = c; c = b; b = a; a = T1 + T2; } /* Add the starting values of the context according to FIPS 180-2:6.2.2 step 4. */ a += a_save; b += b_save; c += c_save; d += d_save; e += e_save; f += f_save; g += g_save; h += h_save; /* Prepare for the next round. */ nwords -= 16; } /* Put checksum in context given as argument. */ ctx->H[0] = a; ctx->H[1] = b; ctx->H[2] = c; ctx->H[3] = d; ctx->H[4] = e; ctx->H[5] = f; ctx->H[6] = g; ctx->H[7] = h; } uint8_t* sha256_direct(const void *buffer, size_t sz, uint8_t result[static SHA256_DIGEST_SIZE]) { struct sha256_ctx ctx; sha256_init_ctx(&ctx); sha256_process_bytes(buffer, sz, &ctx); return sha256_finish_ctx(&ctx, result); }