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#include "id.h"
#include "musl-libgen-c.h"
#include "random-seed.h"
#include "util.h"
#include <assert.h>
#include <errno.h>
#include <fcntl.h>
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
static const char *HEX_CHARS = "0123456789abcdef";
/** Encode hex.
*
* \param dest where to store the encoded data (must have at least size*2+1 bytes)
* \param src the data to encode
* \param size the number of bytes to encode
*/
static void mem2hex(char *dest, const void *src, size_t size) {
size_t i;
for (i = 0; i < size; i++) {
unsigned char c = *((const unsigned char *)src + i);
dest[2*i] = HEX_CHARS[c >> 4];
dest[2*i+1] = HEX_CHARS[c & 0xf];
}
dest[2*i] = '\0';
}
static bool get_rand_pool(unsigned char *buf) {
size_t rand_bytes_gotten = 0;
do {
long this_rand_bytes_gotten = random_get(buf + rand_bytes_gotten, RAND_POOL_SIZE - rand_bytes_gotten, 0);
if (this_rand_bytes_gotten == -1) {
switch (errno) {
case EAGAIN: continue;
case EINTR: return false;
default:
perror("getrandom");
exit(1);
}
} else {
rand_bytes_gotten += (size_t)this_rand_bytes_gotten;
}
} while (rand_bytes_gotten < RAND_POOL_SIZE);
return true;
}
static void hash_str(const unsigned char salt[static SALT_LEN], char hash_out[static HASH_STR_LEN], const void *buf, size_t buflen) {
unsigned char digest[HASH_LEN];
hash(salt, digest, buf, buflen);
mem2hex(hash_out, digest, HASH_LEN);
}
/**
* Save entropy to disk.
*
* \param seed_path the seed file path
* \param random_buf the random buffer. if NULL, get our own entropy.
* \return true means saved successfully, false means received EINTR
*/
bool save(const char *seed_path, const unsigned char *random_ptr) {
assert(seed_path);
bool rv = false;
unsigned char random_buf[RAND_POOL_SIZE];
if (!random_ptr) {
if (!get_rand_pool(random_buf))
return false;
random_ptr = random_buf;
}
const char *machine_id = get_machine_id(&machine_id);
if (!machine_id)
return false;
char machine_id_hash[HASH_STR_LEN];
hash_str(random_ptr, machine_id_hash, machine_id, strlen(machine_id));
struct random_seed rs = {0};
char *seed_path_tmp = strdup(seed_path);
const char *seed_dir, *seed_name;
char *seed_path_last_slash = strrchr(seed_path_tmp, '/');
if (seed_path_last_slash) {
*seed_path_last_slash = '\0';
seed_dir = seed_path_tmp;
seed_name = seed_path_last_slash + 1;
} else {
free(seed_path_tmp);
seed_path_tmp = NULL;
seed_dir = ".";
seed_name = seed_path;
}
char *seed_name_new = NULL;
if (asprintf(&seed_name_new, ".%s.new", seed_name) == -1) {
fputs("out of memory\n", stderr);
goto out;
}
int seed_dir_fd = open(seed_dir, O_RDONLY | O_DIRECTORY);
if (seed_dir_fd == -1) {
perror("error opening seed directory");
goto out;
}
fsid_t fs_id;
bool have_fs_id = get_fs_id(&fs_id, seed_dir_fd);
#ifdef HAVE_FS_UUID
(void)have_fs_id;
#else
if (!have_fs_id) {
fputs("error getting fs id\n", stderr);
return false;
}
#endif
char fs_id_hash[HASH_STR_LEN];
hash_str(random_ptr, fs_id_hash, &fs_id, sizeof(fs_id));
#ifdef HAVE_FS_UUID
ensure_rs_device(&rs, seed_dir_fd);
char fs_uuid_hash[HASH_STR_LEN];
{
const char *fs_uuid = get_fs_uuid(&rs);
if (!fs_uuid) {
fputs("error getting fs uuid\n", stderr);
return false;
}
hash_str(random_ptr, fs_uuid_hash, fs_uuid, strlen(fs_uuid));
}
#endif
#ifdef HAVE_LIBUDEV
bool have_drive_id = false;
char drive_id_hash[HASH_STR_LEN];
{
const char *drive_id = get_drive_id(&rs);
if (drive_id) {
have_drive_id = true;
hash_str(random_ptr, drive_id_hash, drive_id, strlen(drive_id));
}
}
#endif
{
int seed_fd = openat(seed_dir_fd, seed_name_new, O_WRONLY | O_CREAT | O_TRUNC, 0600);
if (seed_fd == -1) {
perror("error opening new seed file");
goto err;
}
rs.file = fdopen(seed_fd, "w");
if (!rs.file) {
perror("error converting seed file fd to stream");
goto err;
}
}
if (fwrite(random_ptr, 1, RAND_POOL_SIZE, rs.file) != RAND_POOL_SIZE
|| fputs(MAGIC, rs.file) == EOF
|| fputs("machine-id ", rs.file) == EOF
|| fputs(machine_id_hash, rs.file) == EOF
#ifdef HAVE_FS_UUID
|| fputs("\nfs-uuid ", rs.file) == EOF
|| fputs(fs_uuid_hash, rs.file) == EOF
|| fputs("\nfs-id ", rs.file) == EOF
|| fputs(fs_id_hash, rs.file) == EOF
#else
|| (have_fs_id ? fputs("\nfs-id ", rs.file) == EOF : 0)
|| (have_fs_id ? fputs(fs_id_hash, rs.file) == EOF : 0)
#endif
#ifdef HAVE_LIBUDEV
|| (have_drive_id ? fputs("\ndrive-id ", rs.file) == EOF : 0)
|| (have_drive_id ? fputs(drive_id_hash, rs.file) == EOF : 0)
#endif
|| fputs("\ndone\n", rs.file) == EOF) {
fputs("error writing new seed file\n", stderr);
goto err;
}
if (fflush(rs.file) == EOF) {
perror("error flushing new seed file");
goto err;
}
if (fsync(fileno(rs.file)) == -1) {
perror("error syncing new seed file");
goto err;
}
if (renameat(seed_dir_fd, seed_name_new, seed_dir_fd, seed_name) == -1) {
perror("error installing new seed file");
goto err;
}
if (fclose(rs.file) == EOF) {
perror("error closing new seed file");
goto err;
}
if (fsync(seed_dir_fd) == -1) {
perror("error syncing seed directory");
goto out;
}
rv = true;
goto out;
err:
if (rs.file) {
fclose(rs.file);
if (unlinkat(seed_dir_fd, seed_name_new, 0) == -1) {
perror("error removing temporary seed file");
rv = false;
}
}
out:
if (seed_dir_fd != -1) {
if (close(seed_dir_fd) == -1) {
perror("error closing seed directory");
rv = false;
}
}
free(seed_path_tmp);
free(seed_name_new);
return rv;
}
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