Commit 2b4d4ccb authored by Nick Mathewson's avatar Nick Mathewson 🦀
Browse files

Merge remote-tracking branch 'public/bug7801_v2'

parents d86a45f9 69ab7cd8

changes/bug7801

0 → 100644
+13 −0
Original line number Diff line number Diff line 
  o Minor bugfixes:

    - When choosing which stream on a formerly stalled circuit to wake

      first, make better use of the platform's weak RNG.  Previously, we

      had been using the % ("modulo") operator to try to generate a 1/N

      chance of picking each stream, but this behaves badly with many

      platforms' choice of weak RNG. Fix for bug 7801; bugfix on

      0.2.2.20-alpha.

    - Use our own weak RNG when we need a weak RNG. Windows's rand()

      and Irix's random() only return 15 bits; Solaris's random()

      returns more bits but its RAND_MAX says it only returns 15, and

      so on.  Fixes another aspect of bug 7801; bugfix on

      0.2.2.20-alpha.

src/common/compat.c

+0 −24
Original line number Diff line number Diff line
@@ -2059,30 +2059,6 @@ tor_lookup_hostname(const char *name, uint32_t *addr) 
  return -1;

}



/** Initialize the insecure libc RNG. */

void

tor_init_weak_random(unsigned seed)

{

#ifdef _WIN32

  srand(seed);

#else

  srandom(seed);

#endif

}



/** Return a randomly chosen value in the range 0..TOR_RAND_MAX.  This

 * entropy will not be cryptographically strong; do not rely on it

 * for anything an adversary should not be able to predict. */

long

tor_weak_random(void)

{

#ifdef _WIN32

  return rand();

#else

  return random();

#endif

}



/** Hold the result of our call to <b>uname</b>. */

static char uname_result[256];

/** True iff uname_result is set. */

src/common/compat.h

+0 −5
Original line number Diff line number Diff line
@@ -581,11 +581,6 @@ typedef enum { 
  SOCKS5_ADDRESS_TYPE_NOT_SUPPORTED = 0x08,

} socks5_reply_status_t;



/* ===== Insecure rng */

void tor_init_weak_random(unsigned seed);

long tor_weak_random(void);

#define TOR_RAND_MAX (RAND_MAX)



/* ===== OS compatibility */

const char *get_uname(void);

src/common/crypto.c

+4 −4
Original line number Diff line number Diff line
@@ -2337,12 +2337,12 @@ crypto_dh_free(crypto_dh_t *dh) 
  (OPENSSL_VERSION_NUMBER >= OPENSSL_V(0,9,8,'c'))



/** Set the seed of the weak RNG to a random value. */

static void

seed_weak_rng(void)

void

crypto_seed_weak_rng(tor_weak_rng_t *rng)

{

  unsigned seed;

  crypto_rand((void*)&seed, sizeof(seed));

  tor_init_weak_random(seed);

  tor_init_weak_random(rng, seed);

}



/** Try to get <b>out_len</b> bytes of the strongest entropy we can generate,
@@ -2426,7 +2426,7 @@ crypto_seed_rng(int startup) 
  }



  memwipe(buf, 0, sizeof(buf));

  seed_weak_rng();



  if (rand_poll_ok || load_entropy_ok)

    return 0;

  else

src/common/crypto.h

+2 −0
Original line number Diff line number Diff line
@@ -256,6 +256,8 @@ int crypto_strongest_rand(uint8_t *out, size_t out_len); 
int crypto_rand_int(unsigned int max);

uint64_t crypto_rand_uint64(uint64_t max);

double crypto_rand_double(void);

struct tor_weak_rng_t;

void crypto_seed_weak_rng(struct tor_weak_rng_t *rng);



char *crypto_random_hostname(int min_rand_len, int max_rand_len,

                             const char *prefix, const char *suffix);