RNG_SystemRNG should fail rather than falling back on rng_systemFromNoise

nss/lib/freebl/unix_rand.c

Index: nss/lib/freebl/unix_rand.c
===================================================================
--- nss/lib/freebl/unix_rand.c	(revision 206814)
+++ nss/lib/freebl/unix_rand.c	(working copy)
@@ -916,7 +916,7 @@
 #if defined(BSDI) || defined(FREEBSD) || defined(NETBSD) \
     || defined(OPENBSD) || defined(DARWIN) || defined(LINUX) \
     || defined(HPUX)
-    if (bytes)
+    if (bytes == SYSTEM_RNG_SEED_COUNT)
         return;
 
     /*
@@ -924,8 +924,9 @@
      *
      * See crbug.com/244661 for details.
      */
-    fprintf(stderr, "[ERROR:%s(%d)] NSS failed to read from /dev/urandom. "
-            "Abort process.\n", __FILE__, __LINE__);
+    fprintf(stderr, "[ERROR:%s(%d)] NSS read %d bytes (expected %d bytes) "
+            "from /dev/urandom. Abort process.\n", __FILE__, __LINE__,
+            (int)bytes, SYSTEM_RNG_SEED_COUNT);

[wtc, 2013/06/17 23:04:17]

|bytes| is a size_t, so we need the (int) cast to match the %d
format specifier.

[Ryan Sleevi, 2013/06/17 23:19:17]

Is NSS allowed to use C99, or is it limited to C89?

I'm wondering whether the C99 zu is sufficient here. Still, your int cast is
probably fine too.

     fflush(stderr);
     abort();
 #endif
@@ -1133,6 +1134,11 @@
    }
 }
 
+/*
+ * Modified to abort the process if it failed to read from /dev/urandom.
+ *
+ * See crbug.com/244661 for details.
+ */
 size_t RNG_SystemRNG(void *dest, size_t maxLen)
 {
     FILE *file;
@@ -1142,11 +1148,6 @@
 
     file = fopen("/dev/urandom", "r");
     if (file == NULL) {
-	/*
-	 * Modified to abort the process if it failed to read from /dev/urandom.
-	 *
-	 * See crbug.com/244661 for details.
-	 */
 	fprintf(stderr, "[ERROR:%s(%d)] NSS failed to read from /dev/urandom. "
 		"Abort process.\n", __FILE__, __LINE__);
 	fflush(stderr);
@@ -1162,8 +1163,10 @@
     }
     fclose(file);
     if (fileBytes != maxLen) {
-	PORT_SetError(SEC_ERROR_NEED_RANDOM);  /* system RNG failed */
-	fileBytes = 0;
+	fprintf(stderr, "[ERROR:%s(%d)] NSS failed to read from /dev/urandom. "
+		"Abort process.\n", __FILE__, __LINE__);
+	fflush(stderr);
+	abort();
     }
     return fileBytes;
 }