1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
2
3 /* Stolen from glibc and converted to our 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 #ifndef SD_BOOT
27 #include <string.h>
28 #endif
29
30 #include "macro-fundamental.h"
31 #include "sha256.h"
32
33 #if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
34 # define SWAP(n) \
35 (((n) << 24) | (((n) & 0xff00) << 8) | (((n) >> 8) & 0xff00) | ((n) >> 24))
36 # define SWAP64(n) \
37 (((n) << 56) \
38 | (((n) & 0xff00) << 40) \
39 | (((n) & 0xff0000) << 24) \
40 | (((n) & 0xff000000) << 8) \
41 | (((n) >> 8) & 0xff000000) \
42 | (((n) >> 24) & 0xff0000) \
43 | (((n) >> 40) & 0xff00) \
44 | ((n) >> 56))
45 #else
46 # define SWAP(n) (n)
47 # define SWAP64(n) (n)
48 #endif
49
50 /* This array contains the bytes used to pad the buffer to the next
51 64-byte boundary. (FIPS 180-2:5.1.1) */
52 static const uint8_t fillbuf[64] = {
53 0x80, 0 /* , 0, 0, ... */
54 };
55
56 /* Constants for SHA256 from FIPS 180-2:4.2.2. */
57 static const uint32_t K[64] = {
58 0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5,
59 0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
60 0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3,
61 0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
62 0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc,
63 0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
64 0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7,
65 0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
66 0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13,
67 0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
68 0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3,
69 0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
70 0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5,
71 0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
72 0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208,
73 0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2
74 };
75
76 static void sha256_process_block(const void *, size_t, struct sha256_ctx *);
77
78 /* Initialize structure containing state of computation.
79 (FIPS 180-2:5.3.2) */
sha256_init_ctx(struct sha256_ctx * ctx)80 void sha256_init_ctx(struct sha256_ctx *ctx) {
81 assert(ctx);
82
83 ctx->H[0] = 0x6a09e667;
84 ctx->H[1] = 0xbb67ae85;
85 ctx->H[2] = 0x3c6ef372;
86 ctx->H[3] = 0xa54ff53a;
87 ctx->H[4] = 0x510e527f;
88 ctx->H[5] = 0x9b05688c;
89 ctx->H[6] = 0x1f83d9ab;
90 ctx->H[7] = 0x5be0cd19;
91
92 ctx->total64 = 0;
93 ctx->buflen = 0;
94 }
95
96 /* Process the remaining bytes in the internal buffer and the usual
97 prolog according to the standard and write the result to RESBUF.
98
99 IMPORTANT: On some systems it is required that RESBUF is correctly
100 aligned for a 32 bits value. */
sha256_finish_ctx(struct sha256_ctx * ctx,void * resbuf)101 void *sha256_finish_ctx(struct sha256_ctx *ctx, void *resbuf) {
102 /* Take yet unprocessed bytes into account. */
103 uint32_t bytes = ctx->buflen;
104 size_t pad;
105
106 assert(ctx);
107 assert(resbuf);
108
109 /* Now count remaining bytes. */
110 ctx->total64 += bytes;
111
112 pad = bytes >= 56 ? 64 + 56 - bytes : 56 - bytes;
113 memcpy(&ctx->buffer[bytes], fillbuf, pad);
114
115 /* Put the 64-bit file length in *bits* at the end of the buffer. */
116 ctx->buffer32[(bytes + pad + 4) / 4] = SWAP(ctx->total[TOTAL64_low] << 3);
117 ctx->buffer32[(bytes + pad) / 4] = SWAP((ctx->total[TOTAL64_high] << 3)
118 | (ctx->total[TOTAL64_low] >> 29));
119
120 /* Process last bytes. */
121 sha256_process_block(ctx->buffer, bytes + pad + 8, ctx);
122
123 /* Put result from CTX in first 32 bytes following RESBUF. */
124 for (size_t i = 0; i < 8; ++i)
125 ((uint32_t *) resbuf)[i] = SWAP(ctx->H[i]);
126
127 return resbuf;
128 }
129
sha256_process_bytes(const void * buffer,size_t len,struct sha256_ctx * ctx)130 void sha256_process_bytes(const void *buffer, size_t len, struct sha256_ctx *ctx) {
131 assert(buffer);
132 assert(ctx);
133
134 /* When we already have some bits in our internal buffer concatenate
135 both inputs first. */
136
137 if (ctx->buflen != 0) {
138 size_t left_over = ctx->buflen;
139 size_t add = 128 - left_over > len ? len : 128 - left_over;
140
141 memcpy(&ctx->buffer[left_over], buffer, add);
142 ctx->buflen += add;
143
144 if (ctx->buflen > 64) {
145 sha256_process_block(ctx->buffer, ctx->buflen & ~63, ctx);
146
147 ctx->buflen &= 63;
148 /* The regions in the following copy operation cannot overlap. */
149 memcpy(ctx->buffer, &ctx->buffer[(left_over + add) & ~63],
150 ctx->buflen);
151 }
152
153 buffer = (const char *) buffer + add;
154 len -= add;
155 }
156
157 /* Process available complete blocks. */
158 if (len >= 64) {
159
160 /* The condition below is from glibc's string/string-inline.c.
161 * See definition of _STRING_INLINE_unaligned. */
162 #if !defined(__mc68020__) && !defined(__s390__) && !defined(__i386__)
163
164 /* To check alignment gcc has an appropriate operator. Other compilers don't. */
165 # if __GNUC__ >= 2
166 # define UNALIGNED_P(p) (((size_t) p) % __alignof__(uint32_t) != 0)
167 # else
168 # define UNALIGNED_P(p) (((size_t) p) % sizeof(uint32_t) != 0)
169 # endif
170 if (UNALIGNED_P(buffer))
171 while (len > 64) {
172 memcpy(ctx->buffer, buffer, 64);
173 sha256_process_block(ctx->buffer, 64, ctx);
174 buffer = (const char *) buffer + 64;
175 len -= 64;
176 }
177 else
178 #endif
179 {
180 sha256_process_block(buffer, len & ~63, ctx);
181 buffer = (const char *) buffer + (len & ~63);
182 len &= 63;
183 }
184 }
185
186 /* Move remaining bytes into internal buffer. */
187 if (len > 0) {
188 size_t left_over = ctx->buflen;
189
190 memcpy(&ctx->buffer[left_over], buffer, len);
191 left_over += len;
192 if (left_over >= 64) {
193 sha256_process_block(ctx->buffer, 64, ctx);
194 left_over -= 64;
195 memcpy(ctx->buffer, &ctx->buffer[64], left_over);
196 }
197 ctx->buflen = left_over;
198 }
199 }
200
201
202 /* Process LEN bytes of BUFFER, accumulating context into CTX.
203 It is assumed that LEN % 64 == 0. */
sha256_process_block(const void * buffer,size_t len,struct sha256_ctx * ctx)204 static void sha256_process_block(const void *buffer, size_t len, struct sha256_ctx *ctx) {
205 const uint32_t *words = buffer;
206 size_t nwords = len / sizeof(uint32_t);
207
208 assert(buffer);
209 assert(ctx);
210
211 uint32_t a = ctx->H[0];
212 uint32_t b = ctx->H[1];
213 uint32_t c = ctx->H[2];
214 uint32_t d = ctx->H[3];
215 uint32_t e = ctx->H[4];
216 uint32_t f = ctx->H[5];
217 uint32_t g = ctx->H[6];
218 uint32_t h = ctx->H[7];
219
220 /* First increment the byte count. FIPS 180-2 specifies the possible
221 length of the file up to 2^64 bits. Here we only compute the
222 number of bytes. */
223 ctx->total64 += len;
224
225 /* Process all bytes in the buffer with 64 bytes in each round of
226 the loop. */
227 while (nwords > 0) {
228 uint32_t W[64];
229 uint32_t a_save = a;
230 uint32_t b_save = b;
231 uint32_t c_save = c;
232 uint32_t d_save = d;
233 uint32_t e_save = e;
234 uint32_t f_save = f;
235 uint32_t g_save = g;
236 uint32_t h_save = h;
237
238 /* Operators defined in FIPS 180-2:4.1.2. */
239 #define Ch(x, y, z) ((x & y) ^ (~x & z))
240 #define Maj(x, y, z) ((x & y) ^ (x & z) ^ (y & z))
241 #define S0(x) (CYCLIC (x, 2) ^ CYCLIC (x, 13) ^ CYCLIC (x, 22))
242 #define S1(x) (CYCLIC (x, 6) ^ CYCLIC (x, 11) ^ CYCLIC (x, 25))
243 #define R0(x) (CYCLIC (x, 7) ^ CYCLIC (x, 18) ^ (x >> 3))
244 #define R1(x) (CYCLIC (x, 17) ^ CYCLIC (x, 19) ^ (x >> 10))
245
246 /* It is unfortunate that C does not provide an operator for
247 cyclic rotation. Hope the C compiler is smart enough. */
248 #define CYCLIC(w, s) ((w >> s) | (w << (32 - s)))
249
250 /* Compute the message schedule according to FIPS 180-2:6.2.2 step 2. */
251 for (size_t t = 0; t < 16; ++t) {
252 W[t] = SWAP (*words);
253 ++words;
254 }
255 for (size_t t = 16; t < 64; ++t)
256 W[t] = R1 (W[t - 2]) + W[t - 7] + R0 (W[t - 15]) + W[t - 16];
257
258 /* The actual computation according to FIPS 180-2:6.2.2 step 3. */
259 for (size_t t = 0; t < 64; ++t) {
260 uint32_t T1 = h + S1 (e) + Ch (e, f, g) + K[t] + W[t];
261 uint32_t T2 = S0 (a) + Maj (a, b, c);
262 h = g;
263 g = f;
264 f = e;
265 e = d + T1;
266 d = c;
267 c = b;
268 b = a;
269 a = T1 + T2;
270 }
271
272 /* Add the starting values of the context according to FIPS 180-2:6.2.2
273 step 4. */
274 a += a_save;
275 b += b_save;
276 c += c_save;
277 d += d_save;
278 e += e_save;
279 f += f_save;
280 g += g_save;
281 h += h_save;
282
283 /* Prepare for the next round. */
284 nwords -= 16;
285 }
286
287 /* Put checksum in context given as argument. */
288 ctx->H[0] = a;
289 ctx->H[1] = b;
290 ctx->H[2] = c;
291 ctx->H[3] = d;
292 ctx->H[4] = e;
293 ctx->H[5] = f;
294 ctx->H[6] = g;
295 ctx->H[7] = h;
296 }
297