зеркало из https://github.com/github/putty.git
127 строки
3.0 KiB
C
127 строки
3.0 KiB
C
/*
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* sshrand.c: manage the global live PRNG instance.
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*/
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#include "putty.h"
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#include "ssh.h"
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#include <assert.h>
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/* Collect environmental noise every 5 minutes */
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#define NOISE_REGULAR_INTERVAL (5*60*TICKSPERSEC)
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int random_active = 0;
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#ifdef FUZZING
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/*
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* Special dummy version of the RNG for use when fuzzing.
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*/
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void random_add_noise(NoiseSourceId source, const void *noise, int length) { }
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void random_ref(void) { }
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void random_setup_special(void) { }
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void random_unref(void) { }
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void random_read(void *out, size_t size)
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{
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memset(out, 0x45, size); /* Chosen by eight fair coin tosses */
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}
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void random_get_savedata(void **data, int *len) { }
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#else /* !FUZZING */
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/* Dummy structure for the sake of having something to expire_timer_context */
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static struct random_timer_context { int dummy; } random_timer_ctx;
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static prng *global_prng;
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static unsigned long next_noise_collection;
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void random_add_noise(NoiseSourceId source, const void *noise, int length)
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{
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if (!random_active)
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return;
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prng_add_entropy(global_prng, source, make_ptrlen(noise, length));
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}
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static void random_timer(void *ctx, unsigned long now)
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{
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if (random_active > 0 && now == next_noise_collection) {
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noise_regular();
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next_noise_collection =
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schedule_timer(NOISE_REGULAR_INTERVAL, random_timer,
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&random_timer_ctx);
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}
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}
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static void random_seed_callback(void *noise, int length)
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{
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put_data(global_prng, noise, length);
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}
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static void random_create(const ssh_hashalg *hashalg)
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{
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assert(!global_prng);
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global_prng = prng_new(hashalg);
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prng_seed_begin(global_prng);
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noise_get_heavy(random_seed_callback);
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prng_seed_finish(global_prng);
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next_noise_collection =
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schedule_timer(NOISE_REGULAR_INTERVAL, random_timer,
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&random_timer_ctx);
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/* noise_get_heavy probably read our random seed file.
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* Therefore (in fact, even if it didn't), we should write a
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* fresh one, in case another instance of ourself starts up
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* before we finish, and also in case an attacker gets hold of
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* the seed data we used. */
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random_save_seed();
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}
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void random_ref(void)
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{
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if (!random_active++)
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random_create(&ssh_sha256);
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}
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void random_setup_special()
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{
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random_active++;
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random_create(&ssh_sha512);
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}
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void random_reseed(ptrlen seed)
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{
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prng_seed_begin(global_prng);
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put_datapl(global_prng, seed);
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prng_seed_finish(global_prng);
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}
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void random_unref(void)
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{
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assert(random_active > 0);
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if (random_active == 1) {
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random_save_seed();
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expire_timer_context(&random_timer_ctx);
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prng_free(global_prng);
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global_prng = NULL;
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}
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random_active--;
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}
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void random_read(void *buf, size_t size)
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{
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assert(random_active > 0);
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prng_read(global_prng, buf, size);
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}
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void random_get_savedata(void **data, int *len)
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{
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void *buf = snewn(global_prng->savesize, char);
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random_read(buf, global_prng->savesize);
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*len = global_prng->savesize;
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*data = buf;
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}
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#endif /* FUZZING */
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