kosaki	2015-12-01 05:31:31 +0900 (Tue, 01 Dec 2015)

  New Revision: 52815

  http://svn.ruby-lang.org/cgi-bin/viewvc.cgi?view=revision&revision=52815

  Log:
    * random.c (Init_RandomSeed): move all Random::DEFAULT
      construction bits to Init_RandomSeed2. Random::DEFAULT
      and Ruby internal hashes are no longer shared their seed.
    * random.c (Init_RandomSeed2): ditto. And, kill evil
      rb_obj_reveal() stuff.
    * random.c (init_hashseed): add MT argument.
    * random.c: (init_siphash): ditto.
    * test/ruby/test_rand.rb (TestRand#test_default_seed): new
      test for Random::DEFAULT::seed.

  Modified files:
    trunk/ChangeLog
    trunk/random.c
    trunk/test/ruby/test_rand.rb
Index: ChangeLog
===================================================================
--- ChangeLog	(revision 52814)
+++ ChangeLog	(revision 52815)
@@ -1,3 +1,17 @@ https://github.com/ruby/ruby/blob/trunk/ChangeLog#L1
+Thu Oct 22 06:20:48 2015  KOSAKI Motohiro  <kosaki.motohiro@g...>
+
+	* random.c (Init_RandomSeed): move all Random::DEFAULT
+	  construction bits to Init_RandomSeed2. Random::DEFAULT
+	  and Ruby internal hashes are no longer shared their seed.
+	* random.c (Init_RandomSeed2): ditto. And, kill evil
+	  rb_obj_reveal() stuff.
+
+	* random.c (init_hashseed): add MT argument.
+	* random.c: (init_siphash): ditto.
+
+	* test/ruby/test_rand.rb (TestRand#test_default_seed): new
+	  test for Random::DEFAULT::seed.
+
 Thu Oct 22 05:23:48 2015  KOSAKI Motohiro  <kosaki.motohiro@g...>
 
 	* random.c (init_hashseed, init_siphash): extract initialize
Index: test/ruby/test_rand.rb
===================================================================
--- test/ruby/test_rand.rb	(revision 52814)
+++ test/ruby/test_rand.rb	(revision 52815)
@@ -524,4 +524,13 @@ END https://github.com/ruby/ruby/blob/trunk/test/ruby/test_rand.rb#L524
     [1, 2].sample(1, random: gen)
     assert_equal(2, gen.limit, bug7935)
   end
+
+  def test_default_seed
+    assert_separately([], <<-End)
+      seed = Random::DEFAULT::seed
+      rand1 = Random::DEFAULT::rand
+      rand2 = Random.new(seed).rand
+      assert_equal(rand1, rand2)
+    End
+  end
 end
Index: random.c
===================================================================
--- random.c	(revision 52814)
+++ random.c	(revision 52815)
@@ -1452,24 +1452,9 @@ static union { https://github.com/ruby/ruby/blob/trunk/random.c#L1452
     uint32_t u32[(16 * sizeof(uint8_t) - 1) / sizeof(uint32_t)];
 } sipseed;
 
-static VALUE
-init_randomseed(struct MT *mt)
-{
-    uint32_t initial[DEFAULT_SEED_CNT];
-    VALUE seed;
-
-    fill_random_seed(initial);
-    init_by_array(mt, initial, DEFAULT_SEED_CNT);
-    seed = make_seed_value(initial);
-    explicit_bzero(initial, DEFAULT_SEED_LEN);
-    return seed;
-}
-
 static void
-init_hashseed(void)
+init_hashseed(struct MT *mt)
 {
-    struct MT *mt = default_mt();
-
     hashseed = genrand_int32(mt);
 #if SIZEOF_ST_INDEX_T*CHAR_BIT > 4*8
     hashseed <<= 32;
@@ -1486,9 +1471,8 @@ init_hashseed(void) https://github.com/ruby/ruby/blob/trunk/random.c#L1471
 }
 
 static void
-init_siphash(void)
+init_siphash(struct MT *mt)
 {
-    struct MT *mt = default_mt();
     int i;
 
     for (i = 0; i < numberof(sipseed.u32); ++i)
@@ -1512,28 +1496,48 @@ rb_memhash(const void *ptr, long len) https://github.com/ruby/ruby/blob/trunk/random.c#L1496
 #endif
 }
 
+/* Initialize Ruby internal seeds */
 void
 Init_RandomSeed(void)
 {
-    rb_random_t *r = &default_rand;
-    struct MT *mt = &r->mt;
-    VALUE seed = init_randomseed(mt);
+    /*
+      Don't reuse this MT for Random::DEFAULT. Random::DEFAULT::seed shouldn't
+      provide a hint that an attacker guess siphash's seed.
+    */
+    struct MT mt;
+    uint32_t initial_seed[DEFAULT_SEED_CNT];
 
-    init_hashseed();
-    init_siphash();
+    fill_random_seed(initial_seed);
+    init_by_array(&mt, initial_seed, DEFAULT_SEED_CNT);
 
-    rb_global_variable(&r->seed);
-    r->seed = seed;
+    init_hashseed(&mt);
+    init_siphash(&mt);
+
+    explicit_bzero(initial_seed, DEFAULT_SEED_LEN);
 }
 
+static VALUE
+init_randomseed(struct MT *mt)
+{
+    uint32_t initial[DEFAULT_SEED_CNT];
+    VALUE seed;
+
+    fill_random_seed(initial);
+    init_by_array(mt, initial, DEFAULT_SEED_CNT);
+    seed = make_seed_value(initial);
+    explicit_bzero(initial, DEFAULT_SEED_LEN);
+    return seed;
+}
+
+/* construct Random::DEFAULT bits */
 static void
 Init_RandomSeed2(void)
 {
-    VALUE seed = default_rand.seed;
+    rb_random_t *r = &default_rand;
+    struct MT *mt = &r->mt;
 
-    if (RB_TYPE_P(seed, T_BIGNUM)) {
-	rb_obj_reveal(seed, rb_cBignum);
-    }
+    r->seed = init_randomseed(mt);
+    rb_global_variable(&r->seed);
 }
 
 void

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