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-rw-r--r--src/seedrng/seedrng.c249
1 files changed, 138 insertions, 111 deletions
diff --git a/src/seedrng/seedrng.c b/src/seedrng/seedrng.c
index 95fb947d..74804a92 100644
--- a/src/seedrng/seedrng.c
+++ b/src/seedrng/seedrng.c
@@ -44,40 +44,36 @@
#define GRND_INSECURE 0x0004 /* Apparently some headers don't ship with this yet. */
#endif
+#define DEFAULT_SEED_DIR "/var/lib/seedrng"
+#define CREDITABLE_SEED "seed.credit"
+#define NON_CREDITABLE_SEED "seed.no-credit"
+
/* 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,
+ /* This has to come first so following values stay in the 0x100+ range. */
+ LONGOPT_BASE = 0x100,
+ LONGOPT_SEED_DIR,
+ LONGOPT_SKIP_CREDIT,
};
const char *applet = NULL;
-const char *extraopts =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",
+ "Directory for seed files (default: " DEFAULT_SEED_DIR ")",
+ "Skip crediting entropy of seeds",
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;
-
enum blake2s_lengths {
BLAKE2S_BLOCK_LEN = 64,
BLAKE2S_HASH_LEN = 32,
@@ -109,7 +105,7 @@ struct blake2s_state {
static inline void cpu_to_le32_array(uint32_t *buf, unsigned int words)
{
- while (words--) {
+ while (words--) {
*buf = cpu_to_le32(*buf);
++buf;
}
@@ -117,10 +113,10 @@ static inline void cpu_to_le32_array(uint32_t *buf, unsigned int words)
static inline void le32_to_cpu_array(uint32_t *buf, unsigned int words)
{
- while (words--) {
+ while (words--) {
*buf = le32_to_cpup(buf);
++buf;
- }
+ }
}
static inline uint32_t ror32(uint32_t word, unsigned int shift)
@@ -269,15 +265,71 @@ static void blake2s_final(struct blake2s_state *state, uint8_t *out)
memcpy(out, state->h, state->outlen);
}
+static ssize_t getrandom_full(void *buf, size_t count, unsigned int flags)
+{
+ ssize_t ret, total = 0;
+ uint8_t *p = buf;
+
+ do {
+ ret = getrandom(p, count, flags);
+ if (ret < 0 && errno == EINTR)
+ continue;
+ else if (ret < 0)
+ return ret;
+ total += ret;
+ p += ret;
+ count -= ret;
+ } while (count);
+ return total;
+}
+
+static ssize_t read_full(int fd, void *buf, size_t count)
+{
+ ssize_t ret, total = 0;
+ uint8_t *p = buf;
+
+ do {
+ ret = read(fd, p, count);
+ if (ret < 0 && errno == EINTR)
+ continue;
+ else if (ret < 0)
+ return ret;
+ else if (ret == 0)
+ break;
+ total += ret;
+ p += ret;
+ count -= ret;
+ } while (count);
+ return total;
+}
+
+static ssize_t write_full(int fd, const void *buf, size_t count)
+{
+ ssize_t ret, total = 0;
+ const uint8_t *p = buf;
+
+ do {
+ ret = write(fd, p, count);
+ if (ret < 0 && errno == EINTR)
+ continue;
+ else if (ret < 0)
+ return ret;
+ total += ret;
+ p += ret;
+ count -= ret;
+ } while (count);
+ return total;
+}
+
static size_t determine_optimal_seed_len(void)
{
size_t ret = 0;
char poolsize_str[11] = { 0 };
int fd = open("/proc/sys/kernel/random/poolsize", O_RDONLY);
- if (fd < 0 || read(fd, poolsize_str, sizeof(poolsize_str) - 1) < 0) {
+ if (fd < 0 || read_full(fd, poolsize_str, sizeof(poolsize_str) - 1) < 0) {
ewarn("%s: Unable to determine pool size, falling back to %u bits: %s",
- applet, MIN_SEED_LEN * 8, strerror(errno));
+ applet, MIN_SEED_LEN * 8, strerror(errno));
ret = MIN_SEED_LEN;
} else
ret = DIV_ROUND_UP(strtoul(poolsize_str, NULL, 10), 8);
@@ -296,12 +348,11 @@ static int read_new_seed(uint8_t *seed, size_t len, bool *is_creditable)
int urandom_fd;
*is_creditable = false;
- ret = getrandom(seed, len, GRND_NONBLOCK);
+ ret = getrandom_full(seed, len, GRND_NONBLOCK);
if (ret == (ssize_t)len) {
*is_creditable = true;
return 0;
- }
- if (ret == -1 && errno == ENOSYS) {
+ } else if (ret < 0 && errno == ENOSYS) {
struct pollfd random_fd = {
.fd = open("/dev/random", O_RDONLY),
.events = POLLIN
@@ -310,18 +361,19 @@ static int read_new_seed(uint8_t *seed, size_t len, bool *is_creditable)
return -errno;
*is_creditable = poll(&random_fd, 1, 0) == 1;
close(random_fd.fd);
- } else if (getrandom(seed, len, GRND_INSECURE) == (ssize_t)len)
+ } else if (getrandom_full(seed, len, GRND_INSECURE) == (ssize_t)len)
return 0;
urandom_fd = open("/dev/urandom", O_RDONLY);
if (urandom_fd < 0)
- return -errno;
- ret = read(urandom_fd, seed, len);
+ return -1;
+ ret = read_full(urandom_fd, seed, len);
if (ret == (ssize_t)len)
ret = 0;
else
ret = -errno ? -errno : -EIO;
close(urandom_fd);
- return ret;
+ errno = -ret;
+ return ret ? -1 : 0;
}
static int seed_rng(uint8_t *seed, size_t len, bool credit)
@@ -336,96 +388,74 @@ static int seed_rng(uint8_t *seed, size_t len, bool credit)
};
int random_fd, ret;
- if (len > sizeof(req.buffer))
- return -EFBIG;
+ if (len > sizeof(req.buffer)) {
+ errno = EFBIG;
+ return -1;
+ }
memcpy(req.buffer, seed, len);
- random_fd = open("/dev/random", O_RDWR);
+ random_fd = open("/dev/urandom", O_RDONLY);
if (random_fd < 0)
- return -errno;
+ return -1;
ret = ioctl(random_fd, RNDADDENTROPY, &req);
if (ret)
ret = -errno ? -errno : -EIO;
close(random_fd);
- return ret;
+ errno = -ret;
+ return ret ? -1 : 0;
}
-static int seed_from_file_if_exists(const char *filename, bool credit, struct blake2s_state *hash)
+static int seed_from_file_if_exists(const char *filename, int dfd, bool credit, struct blake2s_state *hash)
{
uint8_t seed[MAX_SEED_LEN];
ssize_t seed_len;
- int fd, dfd, ret = 0;
+ int fd = -1, ret = 0;
- fd = open(filename, O_RDONLY);
+ fd = openat(dfd, filename, O_RDONLY);
if (fd < 0 && errno == ENOENT)
return 0;
else if (fd < 0) {
ret = -errno;
eerror("%s: Unable to open seed file: %s", applet, strerror(errno));
- return ret;
- }
- dfd = open(seed_dir, O_DIRECTORY | O_RDONLY);
- if (dfd < 0) {
- ret = -errno;
- close(fd);
- eerror("%s: Unable to open seed directory: %s", applet, strerror(errno));
- return ret;
+ goto out;
}
- seed_len = read(fd, seed, sizeof(seed));
+ seed_len = read_full(fd, seed, sizeof(seed));
if (seed_len < 0) {
ret = -errno;
eerror("%s: Unable to read seed file: %s", applet, strerror(errno));
+ goto out;
}
- close(fd);
- if (ret) {
- close(dfd);
- return ret;
- }
- if ((unlink(filename) < 0 || fsync(dfd) < 0) && seed_len) {
+ if ((unlinkat(dfd, filename, 0) < 0 || fsync(dfd) < 0) && seed_len) {
ret = -errno;
eerror("%s: Unable to remove seed after reading, so not seeding: %s",
- applet, strerror(errno));
+ applet, strerror(errno));
+ goto out;
}
- close(dfd);
- if (ret)
- return ret;
if (!seed_len)
- return 0;
+ goto out;
blake2s_update(hash, &seed_len, sizeof(seed_len));
blake2s_update(hash, seed, seed_len);
einfo("Seeding %zd bits %s crediting", seed_len * 8, credit ? "and" : "without");
- ret = seed_rng(seed, seed_len, credit);
- if (ret < 0)
- eerror("%s: Unable to seed: %s", applet, strerror(-ret));
- return ret;
-}
-
-static void populate_global_paths(void)
-{
- if (!lock_file)
- lock_file = xstrdup("/var/run/seedrng.lock");
- if (!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);
-}
+ if (seed_rng(seed, seed_len, credit) < 0) {
+ ret = -errno;
+ eerror("%s: Unable to seed: %s", applet, strerror(errno));
+ }
-static void cleanup(void)
-{
- free(lock_file);
- free(seed_dir);
- free(creditable_seed);
- free(non_creditable_seed);
+out:
+ if (fd >= 0)
+ close(fd);
+ errno = -ret;
+ return ret ? -1 : 0;
}
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;
+ int opt, fd = -1, dfd = -1, program_ret = 0;
+ char *seed_dir = NULL;
uint8_t new_seed[MAX_SEED_LEN];
size_t new_seed_len;
bool new_seed_creditable;
@@ -433,20 +463,11 @@ int main(int argc, char **argv)
struct blake2s_state hash;
bool skip_credit = false;
- atexit(cleanup);
applet = basename_c(argv[0]);
- if (geteuid())
- eerrorx("%s: superuser access is required", applet);
- umask(0077);
- while ((opt = getopt_long(argc, argv, getoptstring,
- longopts, (int *) 0)) != -1)
+ 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);
@@ -457,7 +478,15 @@ int main(int argc, char **argv)
case_RC_COMMON_GETOPT
}
}
- populate_global_paths();
+ if (!seed_dir)
+ seed_dir = xstrdup(DEFAULT_SEED_DIR);
+ if (getuid()) {
+ eerror("%s: superuser access is required", applet);
+ program_ret = 1;
+ goto out;
+ }
+ umask(0077);
+
blake2s_init(&hash, BLAKE2S_HASH_LEN);
blake2s_update(&hash, seedrng_prefix, strlen(seedrng_prefix));
clock_gettime(CLOCK_REALTIME, &realtime);
@@ -465,28 +494,27 @@ int main(int argc, char **argv)
blake2s_update(&hash, &realtime, sizeof(realtime));
blake2s_update(&hash, &boottime, sizeof(boottime));
- if (mkdir(seed_dir, 0700) < 0 && errno != EEXIST)
- eerrorx("%s: Unable to create \"%s\" directory: %s",
- applet, seed_dir, strerror(errno));
+ if (mkdir(seed_dir, 0700) < 0 && errno != EEXIST) {
+ eerror("%s: Unable to create seed directory: %s", applet, strerror(errno));
+ program_ret = 1;
+ goto out;
+ }
- lock = open(lock_file, O_WRONLY | O_CREAT, 0000);
- if (lock < 0 || flock(lock, LOCK_EX) < 0) {
- eerror("%s: Unable to open lock file: %s", applet, strerror(errno));
+ dfd = open(seed_dir, O_DIRECTORY | O_RDONLY);
+ if (dfd < 0 || flock(dfd, LOCK_EX) < 0) {
+ eerror("%s: Unable to lock seed directory: %s", applet, strerror(errno));
program_ret = 1;
goto out;
}
- ret = seed_from_file_if_exists(non_creditable_seed, false, &hash);
- if (ret < 0)
+ if (seed_from_file_if_exists(NON_CREDITABLE_SEED, dfd, false, &hash) < 0)
program_ret |= 1 << 1;
- ret = seed_from_file_if_exists(creditable_seed, !skip_credit, &hash);
- if (ret < 0)
+ if (seed_from_file_if_exists(CREDITABLE_SEED, dfd, !skip_credit, &hash) < 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("%s: Unable to read new seed: %s", applet, strerror(-ret));
+ if (read_new_seed(new_seed, new_seed_len, &new_seed_creditable) < 0) {
+ eerror("%s: Unable to read new seed: %s", applet, strerror(errno));
new_seed_len = BLAKE2S_HASH_LEN;
strncpy((char *)new_seed, seedrng_failure, new_seed_len);
program_ret |= 1 << 3;
@@ -496,27 +524,26 @@ int main(int argc, char **argv)
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 = openat(dfd, NON_CREDITABLE_SEED, O_WRONLY | O_CREAT | O_TRUNC, 0400);
if (fd < 0) {
- eerror("%s: Unable to open seed file for writing: %s",
- applet, 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) {
+ if (write_full(fd, new_seed, new_seed_len) != (ssize_t)new_seed_len || fsync(fd) < 0) {
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("%s: Unable to make new seed creditable: %s",
- applet, strerror(errno));
+ if (new_seed_creditable && renameat(dfd, NON_CREDITABLE_SEED, dfd, CREDITABLE_SEED) < 0) {
+ ewarn("%s: Unable to make new seed creditable: %s", applet, strerror(errno));
program_ret |= 1 << 6;
}
out:
if (fd >= 0)
close(fd);
- if (lock >= 0)
- close(lock);
+ if (dfd >= 0)
+ close(dfd);
+ free(seed_dir);
return program_ret;
}
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-27 05:29:07 +0000