return rval;
}
+static int
+seed_from_prngd(unsigned char *buf, size_t bytes)
+{
+#ifdef PRNGD_PORT
+ debug("trying egd/prngd port %d", PRNGD_PORT);
+ if (get_random_bytes_prngd(buf, bytes, PRNGD_PORT, NULL) == 0)
+ return 0;
+#endif
+#ifdef PRNGD_SOCKET
+ debug("trying egd/prngd socket %s", PRNGD_SOCKET);
+ if (get_random_bytes_prngd(buf, bytes, 0, PRNGD_SOCKET) == 0)
+ return 0;
+#endif
+ return -1;
+}
+
double
stir_gettimeofday(double entropy_estimate)
{
void
prng_write_seedfile(void)
{
- int fd;
+ int fd, save_errno;
unsigned char seed[SEED_FILE_SIZE];
- char filename[MAXPATHLEN];
+ char filename[MAXPATHLEN], tmpseed[MAXPATHLEN];
struct passwd *pw;
+ mode_t old_umask;
pw = getpwuid(getuid());
if (pw == NULL)
snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir,
SSH_PRNG_SEED_FILE);
- debug("writing PRNG seed to file %.100s", filename);
+ strlcpy(tmpseed, filename, sizeof(tmpseed));
+ if (strlcat(tmpseed, ".XXXXXXXXXX", sizeof(tmpseed)) >=
+ sizeof(tmpseed))
+ fatal("PRNG seed filename too long");
if (RAND_bytes(seed, sizeof(seed)) <= 0)
fatal("PRNG seed extraction failed");
/* Don't care if the seed doesn't exist */
prng_check_seedfile(filename);
- if ((fd = open(filename, O_WRONLY|O_TRUNC|O_CREAT, 0600)) == -1) {
- debug("WARNING: couldn't access PRNG seedfile %.100s "
- "(%.100s)", filename, strerror(errno));
+ old_umask = umask(0177);
+
+ if ((fd = mkstemp(tmpseed)) == -1) {
+ debug("WARNING: couldn't make temporary PRNG seedfile %.100s "
+ "(%.100s)", tmpseed, strerror(errno));
} else {
- if (atomicio(vwrite, fd, &seed, sizeof(seed)) < sizeof(seed))
+ debug("writing PRNG seed to file %.100s", tmpseed);
+ if (atomicio(vwrite, fd, &seed, sizeof(seed)) < sizeof(seed)) {
+ save_errno = errno;
+ close(fd);
+ unlink(tmpseed);
fatal("problem writing PRNG seedfile %.100s "
- "(%.100s)", filename, strerror(errno));
+ "(%.100s)", filename, strerror(save_errno));
+ }
close(fd);
+ debug("moving temporary PRNG seed to file %.100s", filename);
+ if (rename(tmpseed, filename) == -1) {
+ save_errno = errno;
+ unlink(tmpseed);
+ fatal("problem renaming PRNG seedfile from %.100s "
+ "to %.100s (%.100s)", tmpseed, filename,
+ strerror(save_errno));
+ }
}
+ umask(old_umask);
}
void
debug("Seeded RNG with %i bytes from system calls",
(int)stir_from_system());
-#ifdef PRNGD_PORT
- if (get_random_bytes_prngd(buf, bytes, PRNGD_PORT, NULL) == -1)
- fatal("Entropy collection failed");
- RAND_add(buf, bytes, bytes);
-#elif defined(PRNGD_SOCKET)
- if (get_random_bytes_prngd(buf, bytes, 0, PRNGD_SOCKET) == -1)
- fatal("Entropy collection failed");
- RAND_add(buf, bytes, bytes);
-#else
- /* Read in collection commands */
- if (prng_read_commands(SSH_PRNG_COMMAND_FILE) == -1)
- fatal("PRNG initialisation failed -- exiting.");
- debug("Seeded RNG with %i bytes from programs",
- (int)stir_from_programs());
-#endif
+ /* try prngd, fall back to commands if prngd fails or not configured */
+ if (seed_from_prngd(buf, bytes) == 0) {
+ RAND_add(buf, bytes, bytes);
+ } else {
+ /* Read in collection commands */
+ if (prng_read_commands(SSH_PRNG_COMMAND_FILE) == -1)
+ fatal("PRNG initialisation failed -- exiting.");
+ debug("Seeded RNG with %i bytes from programs",
+ (int)stir_from_programs());
+ }
#ifdef USE_SEED_FILES
prng_write_seedfile();
return ret == bytes ? 0 : 1;
}
+
+/*
+ * We may attempt to re-seed during mkstemp if we are using the one in the
+ * compat library (via mkstemp -> _gettemp -> arc4random -> seed_rng) so we
+ * need our own seed_rng(). We must also check that we have enough entropy.
+ */
+void
+seed_rng(void)
+{
+ if (!RAND_status())
+ fatal("Not enough entropy in RNG");
+}