Commit dedea28c authored by Nick Mathewson's avatar Nick Mathewson 🦀
Browse files

Make crypto_seed_rng() and crypto_rand() less scary. 

These functions must really never fail; so have crypto_rand() assert
that it's working okay, and have crypto_seed_rng() demand that
callers check its return value.  Also have crypto_seed_rng() check
RAND_status() before returning.
parent 232ccc18

src/common/compat.h

+2 −0
Original line number Diff line number Diff line
@@ -118,6 +118,7 @@ 
#define ATTR_CONST __attribute__((const))

#define ATTR_MALLOC __attribute__((malloc))

#define ATTR_NORETURN __attribute__((noreturn))

#define ATTR_WUR __attribute__((warn_unused_result))

/* Alas, nonnull is not at present a good idea for us.  We'd like to get

 * warnings when we pass NULL where we shouldn't (which nonnull does, albeit

 * spottily), but we don't want to tell the compiler to make optimizations
@@ -153,6 +154,7 @@ 
#define ATTR_NORETURN

#define ATTR_NONNULL(x)

#define ATTR_UNUSED

#define ATTR_WUR

#define PREDICT_LIKELY(exp) (exp)

#define PREDICT_UNLIKELY(exp) (exp)

#endif

src/common/crypto.c

+6 −4
Original line number Diff line number Diff line
@@ -2358,7 +2358,7 @@ crypto_seed_rng(void) 


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



  if (rand_poll_ok || load_entropy_ok)

  if ((rand_poll_ok || load_entropy_ok) && RAND_status() == 1)

    return 0;

  else

    return -1;
@@ -2380,12 +2380,14 @@ int 
crypto_rand_unmocked(char *to, size_t n)

{

  int r;

  if (n == 0)

    return 0;



  tor_assert(n < INT_MAX);

  tor_assert(to);

  r = RAND_bytes((unsigned char*)to, (int)n);

  if (r == 0)

    crypto_log_errors(LOG_WARN, "generating random data");

  return (r == 1) ? 0 : -1;

  tor_assert(r >= 0);

  return 0;

}



/** Return a pseudorandom integer, chosen uniformly from the values

src/common/crypto.h

+2 −1
Original line number Diff line number Diff line
@@ -16,6 +16,7 @@ 
#include <stdio.h>

#include "torint.h"

#include "testsupport.h"

#include "compat.h"



/*

  Macro to create an arbitrary OpenSSL version number as used by
@@ -258,7 +259,7 @@ int crypto_expand_key_material_rfc5869_sha256( 
                                    uint8_t *key_out, size_t key_out_len);



/* random numbers */

int crypto_seed_rng(void);

int crypto_seed_rng(void) ATTR_WUR;

MOCK_DECL(int,crypto_rand,(char *to, size_t n));

int crypto_rand_unmocked(char *to, size_t n);

int crypto_strongest_rand(uint8_t *out, size_t out_len);

src/or/main.c

+4 −1
Original line number Diff line number Diff line
@@ -1389,7 +1389,10 @@ 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. */

      crypto_seed_rng();

      if (crypto_seed_rng() < 0) {

        log_warn(LD_GENERAL, "Tried to re-seed RNG, but failed. We already "

                 "seeded once, though, so we won't exit here.");

      }

    }

/** How often do we add more entropy to OpenSSL's RNG pool? */

#define ENTROPY_INTERVAL (60*60)

src/test/bench.c

+4 −1
Original line number Diff line number Diff line
@@ -643,7 +643,10 @@ main(int argc, const char **argv) 


  reset_perftime();



  crypto_seed_rng();

  if (crypto_seed_rng() < 0) {

    printf("Couldn't seed RNG; exiting.\n");

    return 1;

  }

  crypto_init_siphash_key();

  options = options_new();

  init_logging(1);