Commit b5b77f8b authored by Nick Mathewson's avatar Nick Mathewson 🌉
Browse files

r19004@catbus: nickm | 2008-03-21 15:18:43 -0400

 Use RAND_poll() again: the bug that made us stop using it has been fixed.

parent 64f38f21
......@@ -24,6 +24,13 @@ Changes in version - 2008-??-??
- Add a couple of extra warnings to --enable-gcc-warnings for GCC 4.3,
and stop using a warning that had become unfixably verbose under GCC
- Start using OpenSSL's RAND_poll() for better (and more portable)
cross-platform entropy collection again. We used to use it, then
stopped using it because of a bug that could crash systems that called
RAND_poll when they had a lot of fds open. It looks like the bug got
fixed in late 2006. Our new behavior is to call RAND_poll() at
startup, and to call RAND_poll() when we reseed later only if we
have a non-buggy OpenSSL version.
o Code simplifications and refactoring:
- Refactor code using connection_ap_handshake_attach_circuit() to
......@@ -1667,19 +1667,29 @@ crypto_dh_free(crypto_dh_env_t *dh)
/* Use RAND_poll if openssl is 0.9.6 release or later. (The "f" means
"release".) */
//#define USE_RAND_POLL (OPENSSL_VERSION_NUMBER >= 0x0090600fl)
#define USE_RAND_POLL 0
/* XXX Somehow setting USE_RAND_POLL on causes stack smashes. We're
* not sure where. This was the big bug with Tor */
/** Seed OpenSSL's random number generator with bytes from the
* operating system. Return 0 on success, -1 on failure.
/* Versions of openssl prior to 0.9.7k and 0.9.8c had a bug where RAND_poll
* would allocate an fd_set on the stack, open a new file, and try to FD_SET
* that fd without checking whether it fit in the fd_set. Thus, if the
* system has not just been started up, it is unsafe to call */
((OPENSSL_VERSION_NUMBER >= 0x009070afl && \
OPENSSL_VERSION_NUMBER <= 0x00907fffl) || \
(OPENSSL_VERSION_NUMBER >= 0x0090803fl))
/* We could actually get away with calling RAND_poll */
/** Seed OpenSSL's random number generator with bytes from the operating
* system. <b>startup</b> should be true iff we have just started Tor and
* have not yet allocated a bunch of fds. Return 0 on success, -1 on failure.
crypto_seed_rng(int startup)
char buf[ADD_ENTROPY];
int rand_poll_status;
int rand_poll_status = 0;
/* local variables */
......@@ -1693,15 +1703,15 @@ crypto_seed_rng(void)
size_t n;
/* OpenSSL 0.9.6 adds a RAND_poll function that knows about more kinds of
* entropy than we do. We'll try calling that, *and* calling our own entropy
* functions. If one succeeds, we'll accept the RNG as seeded. */
rand_poll_status = RAND_poll();
if (rand_poll_status == 0)
log_warn(LD_CRYPTO, "RAND_poll() failed.");
rand_poll_status = 0;
if (startup || RAND_POLL_IS_SAFE) {
rand_poll_status = RAND_poll();
if (rand_poll_status == 0)
log_warn(LD_CRYPTO, "RAND_poll() failed.");
......@@ -166,7 +166,7 @@ int crypto_expand_key_material(const char *key_in, size_t in_len,
char *key_out, size_t key_out_len);
/* random numbers */
int crypto_seed_rng(void);
int crypto_seed_rng(int startup);
int crypto_rand(char *to, size_t n);
int crypto_rand_int(unsigned int max);
uint64_t crypto_rand_uint64(uint64_t max);
......@@ -900,7 +900,7 @@ run_scheduled_events(time_t now)
if (time_to_add_entropy < now) {
if (time_to_add_entropy) {
/* We already seeded once, so don't die on failure. */
/** How often do we add more entropy to OpenSSL's RNG pool? */
#define ENTROPY_INTERVAL (60*60)
......@@ -1810,7 +1810,7 @@ tor_init(int argc, char *argv[])
if (crypto_seed_rng()) {
if (crypto_seed_rng(1)) {
log_err(LD_BUG, "Unable to seed random number generator. Exiting.");
return -1;
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