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annotate pws-random.c @ 9:ec5c1b653ee6

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Prevent NULL pointer dereference Creating the end field may fail, thus try to allocate it in advance.
author Guido Berhoerster <guido+libpws@berhoerster.name>
date Tue, 30 Jul 2019 14:52:29 +0200
parents d541e748cfd8
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1 /*
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2 * Copyright (C) 2015 Guido Berhoerster <guido+libpws@berhoerster.name>
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3 *
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4 * Permission is hereby granted, free of charge, to any person obtaining
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5 * a copy of this software and associated documentation files (the
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6 * "Software"), to deal in the Software without restriction, including
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7 * without limitation the rights to use, copy, modify, merge, publish,
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8 * distribute, sublicense, and/or sell copies of the Software, and to
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9 * permit persons to whom the Software is furnished to do so, subject to
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10 * the following conditions:
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11 *
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12 * The above copyright notice and this permission notice shall be included
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13 * in all copies or substantial portions of the Software.
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14 *
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15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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16 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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17 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
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18 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
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19 * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
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20 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
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21 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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22 */
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23
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24 #include "compat.h"
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25 #include "pws-internal.h"
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26
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27 #ifdef HAVE_ARC4RANDOM
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28 /* prefer system arc4random(3) implementation */
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29 #include <stdlib.h>
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30 #else /* HAVE_ARC4RANDOM */
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31 #ifdef HAVE_GETENTROPY
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32 /*
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33 * otherwise use system getentropy(2) implementation or fallback to seed
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34 * Yarrow-256 PRNG from libnettle
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35 */
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36 #include <unistd.h>
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37 #endif /* HAVE_GETENTROPY */
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38 #include <nettle/yarrow.h>
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39 #endif /* HAVE_ARC4RANDOM */
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40
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41 #include "pws-internal.h"
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42
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43 int
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44 pws_random_bytes(void *buf, size_t buf_size)
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45 {
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46 #ifdef HAVE_ARC4RANDOM
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47 arc4random_buf(buf, buf_size);
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48 #else /* HAVE_ARC4RANDOM */
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49 struct yarrow256_ctx ctx;
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50 unsigned char seed_buf[YARROW256_SEED_FILE_SIZE];
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51
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52 if (getentropy(&seed_buf, sizeof (seed_buf)) != 0) {
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53 return (-1);
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54 }
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55 yarrow256_init(&ctx, 0, NULL);
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56 yarrow256_seed(&ctx, sizeof (seed_buf), seed_buf);
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57 yarrow256_random(&ctx, buf_size, buf);
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58 #endif /* HAVE_ARC4RANDOM */
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59
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60 return (0);
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61 }