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Merge "init: improve mmap ASLR failure reporting"

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This commit is contained in:
Kees Cook 2016-03-24 02:44:25 +00:00 • committed by Gerrit Code Review
commit b27026f925
1 changed files with 18 additions and 4 deletions
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22
init/init.cpp
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@ -310,6 +310,7 @@ static bool __attribute__((unused)) set_mmap_rnd_bits_min(int start, int min, bo
} }
std::ifstream inf(path, std::fstream::in); std::ifstream inf(path, std::fstream::in);
if (!inf) { if (!inf) {
ERROR("Cannot open for reading: %s!\n", path.c_str());
return false; return false;
} }
while (start >= min) { while (start >= min) {
@ -317,6 +318,7 @@ static bool __attribute__((unused)) set_mmap_rnd_bits_min(int start, int min, bo
std::string str_val = std::to_string(start); std::string str_val = std::to_string(start);
std::ofstream of(path, std::fstream::out); std::ofstream of(path, std::fstream::out);
if (!of) { if (!of) {
ERROR("Cannot open for writing: %s!\n", path.c_str());
return false; return false;
} }
of << str_val << std::endl; of << str_val << std::endl;
@ -332,15 +334,27 @@ static bool __attribute__((unused)) set_mmap_rnd_bits_min(int start, int min, bo
start--; start--;
} }
inf.close(); 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 * Set /proc/sys/vm/mmap_rnd_bits and potentially
* /proc/sys/vm/mmap_rnd_compat_bits to the maximum supported values. * /proc/sys/vm/mmap_rnd_compat_bits to the maximum supported values.
* Returns -1 if unable to set these to an acceptable value. Apply * Returns -1 if unable to set these to an acceptable value.
* upstream patch-sets https://lkml.org/lkml/2015/12/21/337 and *
* https://lkml.org/lkml/2016/2/4/831 to enable this. * 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) static int set_mmap_rnd_bits_action(const std::vector<std::string>& args)
{ {