DivestOS/Patches/LineageOS-20.0/android_bionic/0002-Graphene_Bionic_Hardening-3.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Daniel Micay <danielmicay@gmail.com>
Date: Mon, 4 Mar 2019 04:26:04 -0500
Subject: [PATCH] use blocking getrandom and avoid urandom fallback

Signed-off-by: anupritaisno1 <www.anuprita804@gmail.com>
---
 libc/bionic/getentropy.cpp | 28 +++-------------------------
 1 file changed, 3 insertions(+), 25 deletions(-)

diff --git a/libc/bionic/getentropy.cpp b/libc/bionic/getentropy.cpp
index 9c93e713b..c9438ad2b 100644
--- a/libc/bionic/getentropy.cpp
+++ b/libc/bionic/getentropy.cpp
@@ -33,22 +33,6 @@
 
 #include "private/ScopedFd.h"
 
-static int getentropy_urandom(void* buffer, size_t buffer_size, int saved_errno) {
-  ScopedFd fd(TEMP_FAILURE_RETRY(open("/dev/urandom", O_RDONLY | O_NOFOLLOW | O_CLOEXEC, 0)));
-  if (fd.get() == -1) return -1;
-
-  size_t collected = 0;
-  while (collected < buffer_size) {
-    ssize_t count = TEMP_FAILURE_RETRY(read(fd.get(), static_cast<char*>(buffer) + collected,
-                                            buffer_size - collected));
-    if (count == -1) return -1;
-    collected += count;
-  }
-
-  errno = saved_errno;
-  return 0;
-}
-
 int getentropy(void* buffer, size_t buffer_size) {
   if (buffer_size > 256) {
     errno = EIO;
@@ -59,16 +43,10 @@ int getentropy(void* buffer, size_t buffer_size) {
 
   size_t collected = 0;
   while (collected < buffer_size) {
-    long count = TEMP_FAILURE_RETRY(getrandom(static_cast<char*>(buffer) + collected,
-                                              buffer_size - collected, GRND_NONBLOCK));
+    long count = TEMP_FAILURE_RETRY(
+        getrandom(static_cast<char*>(buffer) + collected, buffer_size - collected, 0));
     if (count == -1) {
-      // EAGAIN: there isn't enough entropy right now.
-      // ENOSYS/EINVAL: getrandom(2) or GRND_NONBLOCK isn't supported.
-      // EFAULT: `buffer` is invalid.
-      // Try /dev/urandom regardless because it can't hurt,
-      // and we don't need to optimize the EFAULT case.
-      // See http://b/33059407 and http://b/67015565.
-      return getentropy_urandom(buffer, buffer_size, saved_errno);
+      return -1;
     }
     collected += count;
   }