Merge "Revert "Set mmap_rnd_bits to maximum value.""
am: bb296fd
* commit 'bb296fdaecb3c90c21797dab6abb3add4f84d938':
Revert "Set mmap_rnd_bits to maximum value."
This commit is contained in:
Daniel Cashman
android-build-merger
commit
2a1c430ff4
116
init/init.cpp
116
init/init.cpp
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@ -18,7 +18,6 @@
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#include <dirent.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <fstream>
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#include <libgen.h>
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#include <paths.h>
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#include <signal.h>
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@ -290,114 +289,6 @@ ret:
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return result;
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}
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static void security_failure() {
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ERROR("Security failure; rebooting into recovery mode...\n");
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android_reboot(ANDROID_RB_RESTART2, 0, "recovery");
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while (true) { pause(); } // never reached
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}
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#define MMAP_RND_PATH "/proc/sys/vm/mmap_rnd_bits"
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#define MMAP_RND_COMPAT_PATH "/proc/sys/vm/mmap_rnd_compat_bits"
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/* __attribute__((unused)) due to lack of mips support: see mips block
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* in set_mmap_rnd_bits_action */
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static bool __attribute__((unused)) set_mmap_rnd_bits_min(int start, int min, bool compat) {
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std::string path;
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if (compat) {
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path = MMAP_RND_COMPAT_PATH;
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} else {
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path = MMAP_RND_PATH;
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}
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std::ifstream inf(path, std::fstream::in);
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if (!inf) {
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ERROR("Cannot open for reading: %s!\n", path.c_str());
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return false;
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}
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while (start >= min) {
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// try to write out new value
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std::string str_val = std::to_string(start);
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std::ofstream of(path, std::fstream::out);
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if (!of) {
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ERROR("Cannot open for writing: %s!\n", path.c_str());
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return false;
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}
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of << str_val << std::endl;
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of.close();
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// check to make sure it was recorded
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inf.seekg(0);
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std::string str_rec;
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inf >> str_rec;
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if (str_val.compare(str_rec) == 0) {
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break;
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}
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start--;
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}
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inf.close();
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if (start < min) {
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ERROR("Unable to set minimum required entropy %d in %s!\n",
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min, path.c_str());
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return false;
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}
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return true;
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}
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/*
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* Set /proc/sys/vm/mmap_rnd_bits and potentially
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* /proc/sys/vm/mmap_rnd_compat_bits to the maximum supported values.
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* Returns -1 if unable to set these to an acceptable value.
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*
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* To support this sysctl, the following upstream commits are needed:
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*
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* d07e22597d1d mm: mmap: add new /proc tunable for mmap_base ASLR
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* e0c25d958f78 arm: mm: support ARCH_MMAP_RND_BITS
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* 8f0d3aa9de57 arm64: mm: support ARCH_MMAP_RND_BITS
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* 9e08f57d684a x86: mm: support ARCH_MMAP_RND_BITS
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* ec9ee4acd97c drivers: char: random: add get_random_long()
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* 5ef11c35ce86 mm: ASLR: use get_random_long()
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*/
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static int set_mmap_rnd_bits_action(const std::vector<std::string>& args)
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{
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int ret = -1;
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/* values are arch-dependent */
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#if defined(__aarch64__)
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/* arm64 supports 18 - 33 bits depending on pagesize and VA_SIZE */
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if (set_mmap_rnd_bits_min(33, 24, false)
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&& set_mmap_rnd_bits_min(16, 16, true)) {
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ret = 0;
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}
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#elif defined(__x86_64__)
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/* x86_64 supports 28 - 32 bits */
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if (set_mmap_rnd_bits_min(32, 32, false)
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&& set_mmap_rnd_bits_min(16, 16, true)) {
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ret = 0;
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}
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#elif defined(__arm__) || defined(__i386__)
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/* check to see if we're running on 64-bit kernel */
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bool h64 = !access(MMAP_RND_COMPAT_PATH, F_OK);
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/* supported 32-bit architecture must have 16 bits set */
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if (set_mmap_rnd_bits_min(16, 16, h64)) {
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ret = 0;
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}
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#elif defined(__mips__) || defined(__mips64__)
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// TODO: add mips support b/27788820
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ret = 0;
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#else
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ERROR("Unknown architecture\n");
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#endif
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#ifdef __BRILLO__
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// TODO: b/27794137
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ret = 0;
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#endif
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if (ret == -1) {
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ERROR("Unable to set adequate mmap entropy value!\n");
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security_failure();
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}
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return ret;
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}
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static int keychord_init_action(const std::vector<std::string>& args)
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{
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keychord_init();
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@ -554,6 +445,12 @@ static int audit_callback(void *data, security_class_t /*cls*/, char *buf, size_
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return 0;
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}
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static void security_failure() {
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ERROR("Security failure; rebooting into recovery mode...\n");
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android_reboot(ANDROID_RB_RESTART2, 0, "recovery");
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while (true) { pause(); } // never reached
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}
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static void selinux_initialize(bool in_kernel_domain) {
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Timer t;
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@ -703,7 +600,6 @@ int main(int argc, char** argv) {
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am.QueueBuiltinAction(wait_for_coldboot_done_action, "wait_for_coldboot_done");
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// ... so that we can start queuing up actions that require stuff from /dev.
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am.QueueBuiltinAction(mix_hwrng_into_linux_rng_action, "mix_hwrng_into_linux_rng");
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am.QueueBuiltinAction(set_mmap_rnd_bits_action, "set_mmap_rnd_bits");
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am.QueueBuiltinAction(keychord_init_action, "keychord_init");
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am.QueueBuiltinAction(console_init_action, "console_init");
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