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fs_mgr: overlayfs deal with verity detection issues

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Stop checking verity on each entry in the fstab, collect the verity
list whole and use in the loop.  Open code verity detection for
"system" for cases where device table is incompletely specified, does
not specify a "/" or a "/system" entry.

Test: manual, /system on system-as-root overlays correctly.
Bug: 109821005
Change-Id: I7bc5fbef6577bb0823cb5deb26c370219e4e597b
This commit is contained in:
Mark Salyzyn 2018-08-29 10:44:33 -07:00
parent 8ddded2f96
commit 54e47908c3
1 changed files with 42 additions and 16 deletions
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58
fs_mgr/fs_mgr_overlayfs.cpp
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@ -29,6 +29,7 @@
#include <sys/vfs.h>
#include <unistd.h>
#include <algorithm>
#include <map>
#include <memory>
#include <string>
@ -42,10 +43,12 @@
#include <ext4_utils/ext4_utils.h>
#include <fs_mgr_overlayfs.h>
#include <fstab/fstab.h>
#include <libdm/dm.h>
#include "fs_mgr_priv.h"
using namespace std::literals;
using namespace android::dm;
#if ALLOW_ADBD_DISABLE_VERITY == 0 // If we are a user build, provide stubs
@ -222,13 +225,12 @@ bool fs_mgr_overlayfs_already_mounted(const std::string& mount_point) {
return false;
}
bool fs_mgr_overlayfs_verity_enabled(const std::string& basename_mount_point) {
auto found = false;
fs_mgr_update_verity_state(
[&basename_mount_point, &found](fstab_rec*, const char* mount_point, int, int) {
if (mount_point && (basename_mount_point == mount_point)) found = true;
});
return found;
std::vector<std::string> fs_mgr_overlayfs_verity_enabled_list() {
std::vector<std::string> ret;
fs_mgr_update_verity_state([&ret](fstab_rec*, const char* mount_point, int, int) {
ret.emplace_back(mount_point);
});
return ret;
}
bool fs_mgr_wants_overlayfs(const fstab_rec* fsrec) {
@ -254,7 +256,7 @@ bool fs_mgr_wants_overlayfs(const fstab_rec* fsrec) {
if (!fs_mgr_overlayfs_enabled(fsrec)) return false;
return !fs_mgr_overlayfs_verity_enabled(android::base::Basename(fsrec_mount_point));
return true;
}
bool fs_mgr_rm_all(const std::string& path, bool* change = nullptr) {
@ -445,11 +447,16 @@ std::vector<std::string> fs_mgr_candidate_list(const fstab* fstab,
std::vector<std::string> mounts;
if (!fstab) return mounts;
auto verity = fs_mgr_overlayfs_verity_enabled_list();
for (auto i = 0; i < fstab->num_entries; i++) {
const auto fsrec = &fstab->recs[i];
if (!fs_mgr_wants_overlayfs(fsrec)) continue;
std::string new_mount_point(fs_mgr_mount_point(fstab, fsrec->mount_point));
if (mount_point && (new_mount_point != mount_point)) continue;
if (std::find(verity.begin(), verity.end(), android::base::Basename(new_mount_point)) !=
verity.end()) {
continue;
}
auto duplicate_or_more_specific = false;
for (auto it = mounts.begin(); it != mounts.end();) {
if ((*it == new_mount_point) ||
@ -465,16 +472,35 @@ std::vector<std::string> fs_mgr_candidate_list(const fstab* fstab,
}
if (!duplicate_or_more_specific) mounts.emplace_back(new_mount_point);
}
// if not itemized /system or /, system as root, fake up
// fs_mgr_wants_overlayfs evaluation of /system as candidate.
if ((std::find(mounts.begin(), mounts.end(), "/system") == mounts.end()) &&
!fs_mgr_get_entry_for_mount_point(const_cast<struct fstab*>(fstab), "/") &&
!fs_mgr_get_entry_for_mount_point(const_cast<struct fstab*>(fstab), "/system") &&
(!mount_point || ("/system"s == mount_point)) &&
!fs_mgr_overlayfs_verity_enabled("system")) {
mounts.emplace_back("/system");
// if not itemized /system or /, system as root, fake one up?
// do we want or need to?
if (mount_point && ("/system"s != mount_point)) return mounts;
if (std::find(mounts.begin(), mounts.end(), "/system") != mounts.end()) return mounts;
// fs_mgr_overlayfs_verity_enabled_list says not to?
if (std::find(verity.begin(), verity.end(), "system") != verity.end()) return mounts;
// confirm that fstab is missing system
if (fs_mgr_get_entry_for_mount_point(const_cast<struct fstab*>(fstab), "/")) {
return mounts;
}
if (fs_mgr_get_entry_for_mount_point(const_cast<struct fstab*>(fstab), "/system")) {
return mounts;
}
// Manually check dm state because stunted fstab (w/o system as root) borken
auto& dm = DeviceMapper::Instance();
auto found = false;
for (auto& system : {"system", "vroot"}) {
if (dm.GetState(system) == DmDeviceState::INVALID) continue;
std::vector<DeviceMapper::TargetInfo> table;
found = !dm.GetTableStatus(system, &table) || table.empty() || table[0].data.empty() ||
(table[0].data[0] == 'C') || (table[0].data[0] == 'V');
if (found) break;
}
if (!found) mounts.emplace_back("/system");
return mounts;
}