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random-seed: use getopt()

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It's not really necessary since systemd-random-seed is an internal tool for the
moment but this might change in future (to allow system installers to
initialize a random seed file for example).

Also introducing new options will be easier.
This commit is contained in:
Franck Bui
2022-10-19 15:49:24 +02:00
parent 141d1da021
commit 0d0c6639d4
1 changed files with 103 additions and 13 deletions
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116
src/random-seed/random-seed.c
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@@ -2,6 +2,7 @@
#include <errno.h>
#include <fcntl.h>
#include <getopt.h>
#include <linux/random.h>
#include <sys/ioctl.h>
#if USE_SYS_RANDOM_H
@@ -22,20 +23,34 @@
#include "missing_random.h"
#include "missing_syscall.h"
#include "mkdir.h"
#include "parse-argument.h"
#include "parse-util.h"
#include "pretty-print.h"
#include "random-util.h"
#include "string-table.h"
#include "string-util.h"
#include "strv.h"
#include "sync-util.h"
#include "sha256.h"
#include "terminal-util.h"
#include "util.h"
#include "xattr-util.h"
typedef enum SeedAction {
ACTION_LOAD,
ACTION_SAVE,
_ACTION_MAX,
_ACTION_INVALID = -EINVAL,
} SeedAction;
typedef enum CreditEntropy {
CREDIT_ENTROPY_NO_WAY,
CREDIT_ENTROPY_YES_PLEASE,
CREDIT_ENTROPY_YES_FORCED,
} CreditEntropy;
static SeedAction arg_action = _ACTION_INVALID;
static CreditEntropy may_credit(int seed_fd) {
_cleanup_free_ char *creditable = NULL;
const char *e;
@@ -100,6 +115,78 @@ static CreditEntropy may_credit(int seed_fd) {
return CREDIT_ENTROPY_NO_WAY;
}
static int help(int argc, char *argv[], void *userdata) {
_cleanup_free_ char *link = NULL;
int r;
r = terminal_urlify_man("systemd-random-seed", "8", &link);
if (r < 0)
return log_oom();
printf("%1$s [OPTIONS...] COMMAND\n"
"\n%5$sLoad and save the system random seed at boot and shutdown.%6$s\n"
"\n%3$sCommands:%4$s\n"
" load Load a random seed saved on disk into the kernel entropy pool\n"
" save Save a new random seed on disk\n"
"\n%3$sOptions:%4$s\n"
" -h --help Show this help\n"
" --version Show package version\n"
"\nSee the %2$s for details.\n",
program_invocation_short_name,
link,
ansi_underline(),
ansi_normal(),
ansi_highlight(),
ansi_normal());
return 0;
}
static const char* const seed_action_table[_ACTION_MAX] = {
[ACTION_LOAD] = "load",
[ACTION_SAVE] = "save",
};
DEFINE_PRIVATE_STRING_TABLE_LOOKUP_FROM_STRING(seed_action, SeedAction);
static int parse_argv(int argc, char *argv[]) {
enum {
ARG_VERSION = 0x100,
};
static const struct option options[] = {
{ "help", no_argument, NULL, 'h' },
{ "version", no_argument, NULL, ARG_VERSION },
};
int c;
assert(argc >= 0);
assert(argv);
while ((c = getopt_long(argc, argv, "h", options, NULL)) >= 0)
switch (c) {
case 'h':
return help(0, NULL, NULL);
case ARG_VERSION:
return version();
case '?':
return -EINVAL;
default:
assert_not_reached();
}
if (optind + 1 != argc)
return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "This program requires one argument.");
arg_action = seed_action_from_string(argv[optind]);
if (arg_action < 0)
return log_error_errno(arg_action, "Unknown action '%s'", argv[optind]);
return 1;
}
static int run(int argc, char *argv[]) {
bool read_seed_file, write_seed_file, synchronous, hashed_old_seed = false;
_cleanup_close_ int seed_fd = -1, random_fd = -1;
@@ -112,9 +199,9 @@ static int run(int argc, char *argv[]) {
log_setup();
if (argc != 2)
return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
"This program requires one argument.");
r = parse_argv(argc, argv);
if (r <= 0)
return r;
umask(0022);
@@ -124,11 +211,11 @@ static int run(int argc, char *argv[]) {
if (r < 0)
return log_error_errno(r, "Failed to create directory " RANDOM_SEED_DIR ": %m");
/* When we load the seed we read it and write it to the device and then immediately update the saved seed with
* new data, to make sure the next boot gets seeded differently. */
if (streq(argv[1], "load")) {
/* When we load the seed we read it and write it to the device and then immediately update the saved
* seed with new data, to make sure the next boot gets seeded differently. */
switch (arg_action) {
case ACTION_LOAD:
seed_fd = open(RANDOM_SEED, O_RDWR|O_CLOEXEC|O_NOCTTY|O_CREAT, 0600);
if (seed_fd < 0) {
int open_rw_error = -errno;
@@ -154,9 +241,9 @@ static int run(int argc, char *argv[]) {
read_seed_file = true;
synchronous = true; /* make this invocation a synchronous barrier for random pool initialization */
break;
} else if (streq(argv[1], "save")) {
case ACTION_SAVE:
random_fd = open("/dev/urandom", O_RDONLY|O_CLOEXEC|O_NOCTTY);
if (random_fd < 0)
return log_error_errno(errno, "Failed to open /dev/urandom: %m");
@@ -168,14 +255,17 @@ static int run(int argc, char *argv[]) {
read_seed_file = false;
write_seed_file = true;
synchronous = false;
} else
return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
"Unknown verb '%s'.", argv[1]);
break;
default:
assert_not_reached();
}
if (fstat(seed_fd, &st) < 0)
return log_error_errno(errno, "Failed to stat() seed file " RANDOM_SEED ": %m");
/* If the seed file is larger than what we expect, then honour the existing size and save/restore as much as it says */
/* If the seed file is larger than what we expect, then honour the existing size and save/restore as
* much as it says */
if ((uint64_t) st.st_size > buf_size)
buf_size = MIN(st.st_size, RANDOM_POOL_SIZE_MAX);