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https://github.com/morgan9e/systemd
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d328346944
The actual minimum size of the pool across supported kernel versions is 32 bytes. So adjust this minimum. I've audited every single usage of random_pool_size(), and cannot see anywhere that this would have any impact at all on anything. We could actually just not change the constant and everything would be fine, or we could change it here and that's fine too. From both a functionality and crypto perspective, it doesn't really seem to make a substantive difference any which way, so long as the value is ≥32. However, it's better to be correct and have the function do what it says, so clamp it to the right minimum.
39 lines
1.3 KiB
C
39 lines
1.3 KiB
C
/* SPDX-License-Identifier: LGPL-2.1-or-later */
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#pragma once
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#include <stdbool.h>
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#include <stddef.h>
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#include <stdint.h>
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typedef enum RandomFlags {
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RANDOM_BLOCK = 1 << 0, /* Rather block than return crap randomness (only if the kernel supports that) */
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} RandomFlags;
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int genuine_random_bytes(void *p, size_t n, RandomFlags flags); /* returns "genuine" randomness, optionally filled up with pseudo random, if not enough is available */
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void pseudo_random_bytes(void *p, size_t n); /* returns only pseudo-randommess (but possibly seeded from something better) */
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void random_bytes(void *p, size_t n); /* returns genuine randomness if cheaply available, and pseudo randomness if not. */
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void initialize_srand(void);
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static inline uint64_t random_u64(void) {
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uint64_t u;
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random_bytes(&u, sizeof(u));
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return u;
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}
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static inline uint32_t random_u32(void) {
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uint32_t u;
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random_bytes(&u, sizeof(u));
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return u;
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}
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/* Some limits on the pool sizes when we deal with the kernel random pool */
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#define RANDOM_POOL_SIZE_MIN 32U
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#define RANDOM_POOL_SIZE_MAX (10U*1024U*1024U)
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size_t random_pool_size(void);
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int random_write_entropy(int fd, const void *seed, size_t size, bool credit);
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uint64_t random_u64_range(uint64_t max);
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