82 lines
1.4 KiB
C
82 lines
1.4 KiB
C
/*
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* Checks if LibreSSL's PRNG is fork-safe on Linux.
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* From https://www.agwa.name/blog/post/libressls_prng_is_unsafe_on_linux
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*/
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#include <openssl/rand.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <sys/wait.h>
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static void random_bytes (unsigned char* p, size_t len)
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{
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if (RAND_bytes(p, len) != 1) {
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fprintf(stderr, "RAND_bytes failed\n");
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abort();
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}
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}
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static void random_stir (void)
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{
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if (RAND_poll() != 1) {
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fprintf(stderr, "RAND_poll failed\n");
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abort();
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}
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}
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static void print_buffer (unsigned char* p, size_t len)
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{
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while (len--) {
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printf("%02x", (unsigned int)*p++);
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}
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}
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int main ()
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{
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char c = 0;
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int pipefd[2];
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pipe(pipefd);
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setbuf(stdout, NULL);
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if (fork() == 0) {
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unsigned char buffer[32];
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pid_t grandparent_pid = getpid();
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random_bytes(buffer, sizeof(buffer));
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if (fork() == 0) {
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random_stir();
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setsid();
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while (1) {
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pid_t grandchild_pid = fork();
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if (grandchild_pid == 0) {
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random_stir();
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if (getpid() == grandparent_pid) {
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random_bytes(buffer, sizeof(buffer));
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print_buffer(buffer, sizeof(buffer));
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printf("\n");
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}
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_exit(0);
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}
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wait(NULL);
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if (grandchild_pid == grandparent_pid) {
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break;
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}
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}
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write(pipefd[1], &c, 1);
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_exit(0);
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}
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random_bytes(buffer, sizeof(buffer));
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print_buffer(buffer, sizeof(buffer));
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printf(" ");
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_exit(0);
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}
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wait(NULL);
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close(pipefd[1]);
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read(pipefd[0], &c, 1);
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return 0;
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}
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