From b5b77f8bf37a193f23c5b68f688f6175266a612f Mon Sep 17 00:00:00 2001 From: Nick Mathewson Date: Fri, 21 Mar 2008 19:18:57 +0000 Subject: 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. svn:r14150 --- src/common/crypto.c | 38 ++++++++++++++++++++++++-------------- 1 file changed, 24 insertions(+), 14 deletions(-) (limited to 'src/common/crypto.c') diff --git a/src/common/crypto.c b/src/common/crypto.c index ea70aad4ab..44fa3b2b40 100644 --- a/src/common/crypto.c +++ b/src/common/crypto.c @@ -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 0.1.1.9-alpha. */ +#define HAVE_RAND_POLL (OPENSSL_VERSION_NUMBER >= 0x0090600fl) -/** 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 */ +#define RAND_POLL_IS_SAFE \ + ((OPENSSL_VERSION_NUMBER >= 0x009070afl && \ + OPENSSL_VERSION_NUMBER <= 0x00907fffl) || \ + (OPENSSL_VERSION_NUMBER >= 0x0090803fl)) + +/* We could actually get away with calling RAND_poll */ +#define USE_RAND_POLL (HAVE_RAND_POLL && RAND_POLL_IS_SAFE) + +/** Seed OpenSSL's random number generator with bytes from the operating + * system. startup 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. */ int -crypto_seed_rng(void) +crypto_seed_rng(int startup) { char buf[ADD_ENTROPY]; - int rand_poll_status; + int rand_poll_status = 0; /* local variables */ #ifdef MS_WINDOWS @@ -1693,15 +1703,15 @@ crypto_seed_rng(void) size_t n; #endif -#if USE_RAND_POLL +#if HAVE_RAND_POLL /* 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."); -#else - 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."); + } #endif #ifdef MS_WINDOWS -- cgit v1.2.3-54-g00ecf