init: improve mmap ASLR failure reporting
This should help people track down the reason for entropy setting
failures.
Bug: 27681085
Change-Id: I6bde342ca0215e32c1f851365a1723630c7d4372
diff --git a/init/init.cpp b/init/init.cpp
index 69f0595..a1e659d 100644
--- a/init/init.cpp
+++ b/init/init.cpp
@@ -310,6 +310,7 @@
}
std::ifstream inf(path, std::fstream::in);
if (!inf) {
+ ERROR("Cannot open for reading: %s!\n", path.c_str());
return false;
}
while (start >= min) {
@@ -317,6 +318,7 @@
std::string str_val = std::to_string(start);
std::ofstream of(path, std::fstream::out);
if (!of) {
+ ERROR("Cannot open for writing: %s!\n", path.c_str());
return false;
}
of << str_val << std::endl;
@@ -332,15 +334,27 @@
start--;
}
inf.close();
- return (start >= min);
+ if (start < min) {
+ ERROR("Unable to set minimum required entropy %d in %s!\n",
+ min, path.c_str());
+ return false;
+ }
+ return true;
}
/*
* Set /proc/sys/vm/mmap_rnd_bits and potentially
* /proc/sys/vm/mmap_rnd_compat_bits to the maximum supported values.
- * Returns -1 if unable to set these to an acceptable value. Apply
- * upstream patch-sets https://lkml.org/lkml/2015/12/21/337 and
- * https://lkml.org/lkml/2016/2/4/831 to enable this.
+ * Returns -1 if unable to set these to an acceptable value.
+ *
+ * To support this sysctl, the following upstream commits are needed:
+ *
+ * d07e22597d1d mm: mmap: add new /proc tunable for mmap_base ASLR
+ * e0c25d958f78 arm: mm: support ARCH_MMAP_RND_BITS
+ * 8f0d3aa9de57 arm64: mm: support ARCH_MMAP_RND_BITS
+ * 9e08f57d684a x86: mm: support ARCH_MMAP_RND_BITS
+ * ec9ee4acd97c drivers: char: random: add get_random_long()
+ * 5ef11c35ce86 mm: ASLR: use get_random_long()
*/
static int set_mmap_rnd_bits_action(const std::vector<std::string>& args)
{