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seedrng.c: multiple cleanups

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This fixes #508.
This commit is contained in:
William Hubbs 2022-03-30 13:49:28 -05:00
parent 5e1f180f0b
commit df18158e60
3 changed files with 112 additions and 36 deletions
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2
src/rc/Makefile
View File

@ -182,5 +182,5 @@ shell_var: shell_var.o
swclock: swclock.o _usage.o rc-misc.o
${CC} ${LOCAL_CFLAGS} ${LOCAL_LDFLAGS} ${CFLAGS} ${LDFLAGS} -o $@ $^ ${LDADD}
seedrng: seedrng.o
seedrng: seedrng.o _usage.o
${CC} ${LOCAL_CFLAGS} ${LOCAL_LDFLAGS} ${CFLAGS} ${LDFLAGS} -o $@ $^ ${LDADD}

2
src/rc/meson.build
View File

@ -270,7 +270,7 @@ if os == 'Linux'
install_dir: rc_bindir)
executable('seedrng',
['seedrng.c'],
['seedrng.c', usage_c, version_h],
c_args : cc_branding_flags,
include_directories: [incdir, einfo_incdir, rc_incdir],
link_with: [libeinfo, librc],

144
src/rc/seedrng.c
View File

@ -23,6 +23,7 @@
#include <sys/stat.h>
#include <sys/types.h>
#include <fcntl.h>
#include <getopt.h>
#include <poll.h>
#include <unistd.h>
#include <time.h>
@ -37,15 +38,46 @@
#include "rc.h"
#include "einfo.h"
#include "helpers.h"
#include "_usage.h"
#ifndef GRND_INSECURE
#define GRND_INSECURE 0x0004 /* Apparently some headers don't ship with this yet. */
#endif
static const char *SEED_DIR;
static const char *LOCK_FILE;
static char *CREDITABLE_SEED;
static char *NON_CREDITABLE_SEED;
/* Use long option value that is out of range for 8 bit getopt values.
* The exact enum value is internal and can freely change, so we keep the
* options sorted.
*/
enum long_opts {
/* This has to come first so following values stay in the 0x100+ range. */
LONGOPT_BASE = 0x100,
LONGOPT_LOCK_FILE,
LONGOPT_SEED_DIR,
LONGOPT_SKIP_CREDIT,
};
const char *applet = NULL;
const char *extraopts =NULL;
const char getoptstring[] = getoptstring_COMMON;
const struct option longopts[] = {
{ "lock-file", 1, NULL, LONGOPT_LOCK_FILE },
{ "seed-dir", 1, NULL, LONGOPT_SEED_DIR },
{ "skip-credit", 0, NULL, LONGOPT_SKIP_CREDIT },
longopts_COMMON
};
const char * const longopts_help[] = {
"lock file",
"directory for seed files",
"skip credit",
longopts_help_COMMON
};
const char *usagestring = NULL;
static char *lock_file = NULL;
static char *seed_dir = NULL;
static char *creditable_seed = NULL;
static char *non_creditable_seed = NULL;
static bool skip_credit = false;
enum blake2s_lengths {
BLAKE2S_BLOCK_LEN = 64,
@ -245,7 +277,8 @@ static size_t determine_optimal_seed_len(void)
int fd = open("/proc/sys/kernel/random/poolsize", O_RDONLY);
if (fd < 0 || read(fd, poolsize_str, sizeof(poolsize_str) - 1) < 0) {
ewarn("Unable to determine pool size, falling back to %u bits: %s", MIN_SEED_LEN * 8, strerror(errno));
ewarn("%s: Unable to determine pool size, falling back to %u bits: %s",
applet, MIN_SEED_LEN * 8, strerror(errno));
ret = MIN_SEED_LEN;
} else
ret = DIV_ROUND_UP(strtoul(poolsize_str, NULL, 10), 8);
@ -329,20 +362,20 @@ static int seed_from_file_if_exists(const char *filename, bool credit, struct bl
return 0;
else if (fd < 0) {
ret = -errno;
eerror("Unable to open seed file: %s", strerror(errno));
eerror("%s: Unable to open seed file: %s", applet, strerror(errno));
return ret;
}
dfd = open(SEED_DIR, O_DIRECTORY | O_RDONLY);
dfd = open(seed_dir, O_DIRECTORY | O_RDONLY);
if (dfd < 0) {
ret = -errno;
close(fd);
eerror("Unable to open seed directory: %s", strerror(errno));
eerror("%s: Unable to open seed directory: %s", applet, strerror(errno));
return ret;
}
seed_len = read(fd, seed, sizeof(seed));
if (seed_len < 0) {
ret = -errno;
eerror("Unable to read seed file: %s", strerror(errno));
eerror("%s: Unable to read seed file: %s", applet, strerror(errno));
}
close(fd);
if (ret) {
@ -351,7 +384,8 @@ static int seed_from_file_if_exists(const char *filename, bool credit, struct bl
}
if ((unlink(filename) < 0 || fsync(dfd) < 0) && seed_len) {
ret = -errno;
eerror("Unable to remove seed after reading, so not seeding: %s", strerror(errno));
eerror("%s: Unable to remove seed after reading, so not seeding: %s",
applet, strerror(errno));
}
close(dfd);
if (ret)
@ -365,24 +399,41 @@ static int seed_from_file_if_exists(const char *filename, bool credit, struct bl
einfo("Seeding %zd bits %s crediting", seed_len * 8, credit ? "and" : "without");
ret = seed_rng(seed, seed_len, credit);
if (ret < 0)
eerror("Unable to seed: %s", strerror(-ret));
eerror("%s: Unable to seed: %s", applet, strerror(-ret));
return ret;
}
static void populate_global_paths(void)
{
SEED_DIR = getenv("SEEDRNG_SEED_DIR");
if (!SEED_DIR || !*SEED_DIR)
SEED_DIR = "/var/lib/seedrng";
LOCK_FILE = getenv("SEEDRNG_LOCK_FILE");
if (!LOCK_FILE || !*LOCK_FILE)
LOCK_FILE = "/var/run/seedrng.lock";
xasprintf(&CREDITABLE_SEED, "%s/seed.credit", SEED_DIR);
xasprintf(&NON_CREDITABLE_SEED, "%s/seed.no-credit", SEED_DIR);
if (!lock_file) {
lock_file = xstrdup(getenv("SEEDRNG_LOCK_FILE"));
if (!lock_file || !*lock_file) {
free(lock_file);
lock_file = xstrdup("/var/run/seedrng.lock");
}
}
if (!seed_dir) {
seed_dir = xstrdup(getenv("SEEDRNG_SEED_DIR"));
if (!seed_dir || !*seed_dir) {
free(seed_dir);
seed_dir = xstrdup("/var/lib/seedrng");
}
}
xasprintf(&creditable_seed, "%s/seed.credit", seed_dir);
xasprintf(&non_creditable_seed, "%s/seed.no-credit", seed_dir);
}
int main(int argc _unused, char *argv[] _unused)
static void cleanup(void)
{
free(lock_file);
free(seed_dir);
free(creditable_seed);
free(non_creditable_seed);
}
int main(int argc, char **argv)
{
int opt;
static const char seedrng_prefix[] = "SeedRNG v1 Old+New Prefix";
static const char seedrng_failure[] = "SeedRNG v1 No New Seed Failure";
int ret, fd = -1, lock, program_ret = 0;
@ -392,10 +443,30 @@ int main(int argc _unused, char *argv[] _unused)
struct timespec realtime = { 0 }, boottime = { 0 };
struct blake2s_state hash;
atexit(cleanup);
applet = basename_c(argv[0]);
if (geteuid())
eerrorx("%s: superuser access is required", applet);
umask(0077);
if (getuid())
eerrorx("This rc helper program requires root");
while ((opt = getopt_long(argc, argv, getoptstring,
longopts, (int *) 0)) != -1)
{
switch (opt) {
case LONGOPT_LOCK_FILE:
if (!lock_file)
lock_file = xstrdup(optarg);
break;
case LONGOPT_SEED_DIR:
if (!seed_dir)
seed_dir = xstrdup(optarg);
break;
case LONGOPT_SKIP_CREDIT:
skip_credit = true;
break;
case_RC_COMMON_GETOPT
}
}
populate_global_paths();
blake2s_init(&hash, BLAKE2S_HASH_LEN);
blake2s_update(&hash, seedrng_prefix, strlen(seedrng_prefix));
@ -404,27 +475,30 @@ int main(int argc _unused, char *argv[] _unused)
blake2s_update(&hash, &realtime, sizeof(realtime));
blake2s_update(&hash, &boottime, sizeof(boottime));
if (mkdir(SEED_DIR, 0700) < 0 && errno != EEXIST)
eerrorx("Unable to create \"%s\" directory: %s", SEED_DIR, strerror(errno));
if (mkdir(seed_dir, 0700) < 0 && errno != EEXIST)
eerrorx("%s: Unable to create \"%s\" directory: %s",
applet, seed_dir, strerror(errno));
lock = open(LOCK_FILE, O_WRONLY | O_CREAT, 0000);
lock = open(lock_file, O_WRONLY | O_CREAT, 0000);
if (lock < 0 || flock(lock, LOCK_EX) < 0) {
eerror("Unable to open lock file: %s", strerror(errno));
eerror("%s: Unable to open lock file: %s", applet, strerror(errno));
program_ret = 1;
goto out;
}
ret = seed_from_file_if_exists(NON_CREDITABLE_SEED, false, &hash);
ret = seed_from_file_if_exists(non_creditable_seed, false, &hash);
if (ret < 0)
program_ret |= 1 << 1;
ret = seed_from_file_if_exists(CREDITABLE_SEED, !rc_yesno(getenv("SEEDRNG_SKIP_CREDIT")), &hash);
ret = seed_from_file_if_exists(creditable_seed,
skip_credit ? !skip_credit : !rc_yesno(getenv("SEEDRNG_SKIP_CREDIT")),
&hash);
if (ret < 0)
program_ret |= 1 << 2;
new_seed_len = determine_optimal_seed_len();
ret = read_new_seed(new_seed, new_seed_len, &new_seed_creditable);
if (ret < 0) {
eerror("Unable to read new seed: %s", strerror(-ret));
eerror("%s: Unable to read new seed: %s", applet, strerror(-ret));
new_seed_len = BLAKE2S_HASH_LEN;
strncpy((char *)new_seed, seedrng_failure, new_seed_len);
program_ret |= 1 << 3;
@ -434,19 +508,21 @@ int main(int argc _unused, char *argv[] _unused)
blake2s_final(&hash, new_seed + new_seed_len - BLAKE2S_HASH_LEN);
einfo("Saving %zu bits of %s seed for next boot", new_seed_len * 8, new_seed_creditable ? "creditable" : "non-creditable");
fd = open(NON_CREDITABLE_SEED, O_WRONLY | O_CREAT | O_TRUNC, 0400);
fd = open(non_creditable_seed, O_WRONLY | O_CREAT | O_TRUNC, 0400);
if (fd < 0) {
eerror("Unable to open seed file for writing: %s", strerror(errno));
eerror("%s: Unable to open seed file for writing: %s",
applet, strerror(errno));
program_ret |= 1 << 4;
goto out;
}
if (write(fd, new_seed, new_seed_len) != (ssize_t)new_seed_len || fsync(fd) < 0) {
eerror("Unable to write seed file: %s", strerror(errno));
eerror("%s: Unable to write seed file: %s", applet, strerror(errno));
program_ret |= 1 << 5;
goto out;
}
if (new_seed_creditable && rename(NON_CREDITABLE_SEED, CREDITABLE_SEED) < 0) {
ewarn("Unable to make new seed creditable: %s", strerror(errno));
if (new_seed_creditable && rename(non_creditable_seed, creditable_seed) < 0) {
ewarn("%s: Unable to make new seed creditable: %s",
applet, strerror(errno));
program_ret |= 1 << 6;
}
out: