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Don't allow cloning root nodes

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The root nodes are /system and /vendor. Adding new files into these
directories, although works on some devices, mostly bootloops on many
devices out there. So don't allow it, which also makes the whole magic
mounting logic much easier and extensible.
This commit is contained in:
topjohnwu 2019-04-08 12:30:57 -04:00
parent dab32e1599
commit f24df4f43d
1 changed files with 41 additions and 39 deletions
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80
native/jni/core/bootstages.cpp
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@ -28,7 +28,6 @@ using namespace std;
static char buf[PATH_MAX], buf2[PATH_MAX];
static vector<string> module_list;
static bool seperate_vendor;
static bool no_secure_dir = false;
static int bind_mount(const char *from, const char *to, bool log = true);
@ -76,7 +75,8 @@ private:
this->parent = parent;
this->module = module;
}
bool is_vendor();
bool is_special();
bool is_root();
string get_path();
void insert(node_entry *&);
void clone_skeleton();
@ -88,10 +88,14 @@ node_entry::~node_entry() {
delete node;
}
bool node_entry::is_vendor() {
bool node_entry::is_special() {
return parent ? (parent->parent ? false : name == "vendor") : false;
}
bool node_entry::is_root() {
return parent ? (parent->parent ? false : name == "vendor") : true;
}
string node_entry::get_path() {
get_path(buf);
return buf;
@ -140,35 +144,45 @@ void node_entry::create_module_tree(const char *module) {
// buf = real path, buf2 = module path
snprintf(buf, PATH_MAX, "%s/%s", full_path.c_str(), entry->d_name);
int eo2 = snprintf(buf2, PATH_MAX, MODULEROOT "/%s%s/%s",
int eof = snprintf(buf2, PATH_MAX, MODULEROOT "/%s%s/%s",
module, full_path.c_str(), entry->d_name);
/*
* Clone the parent in the following condition:
* 1. File in module is a symlink
* 2. Target file do not exist
* 3. Target file is a symlink (exclude /system/vendor)
* Clone current node directory in the following condition:
* 1. We are not a root node
* 2. Target does not exist or
* 3. Module file is a symlink or
* 4. Target file is a symlink (exclude special nodes)
*/
bool clone = false;
if (IS_LNK(node) || access(buf, F_OK) == -1) {
clone = true;
} else if (!node->is_vendor()) {
} else if (!node->is_special()) {
struct stat s;
xstat(buf, &s);
xlstat(buf, &s);
if (S_ISLNK(s.st_mode))
clone = true;
}
if (clone && is_root()) {
// Remove both the new node and file that requires cloning ourselves
rm_rf(buf2);
delete node;
continue;
}
if (clone) {
// Mark self as a skeleton
status |= IS_SKEL; /* This will not overwrite if parent is module */
node->status = IS_MODULE;
} else if (node->is_special()) {
// Special nodes will be pulled out as root nodes later
node->status = IS_INTER;
} else {
// Clone attributes from real path
clone_attr(buf, buf2);
if (IS_DIR(node)) {
// Check if marked as replace
strcpy(buf2 + eo2, "/.replace");
strcpy(buf2 + eof, "/.replace");
if (access(buf2, F_OK) == 0) {
// Replace everything, mark as leaf
node->status = IS_MODULE;
@ -227,14 +241,7 @@ void node_entry::clone_skeleton() {
close(creat(buf, 0644));
// Links will be handled later
if (child->is_vendor()) {
if (seperate_vendor) {
cp_afc(MIRRDIR "/system/vendor", "/system/vendor");
VLOGI("copy_link ", "/system/vendor", MIRRDIR "/system/vendor");
}
// Skip
continue;
} else if (child->status & IS_MODULE) {
if (child->status & IS_MODULE) {
// Mount from module file to dummy file
snprintf(buf2, PATH_MAX, "%s/%s%s/%s", MODULEMNT,
child->module, full_path.c_str(), child->name.c_str());
@ -272,19 +279,16 @@ void node_entry::magic_mount() {
for (auto &child : children)
child->magic_mount();
}
// The only thing goes here should be placeholder nodes
// There should be no dummies, so don't need to handle it here
}
node_entry *node_entry::extract(const char *name) {
node_entry *node = nullptr;
// Extract the node out and swap with placeholder
for (auto &child : children) {
if (child->name == name) {
node = child;
child = new node_entry(name);
child->parent = node->parent;
// Extract the node out of the tree
for (auto it = children.begin(); it != children.end(); ++it) {
if ((*it)->name == name) {
node = *it;
node->parent = nullptr;
children.erase(it);
break;
}
}
@ -364,12 +368,12 @@ static bool magisk_env() {
if (str_contains(line, " /system_root ")) {
mount_mirror(system_root, MS_RDONLY);
xsymlink(MIRRMNT(system_root) "/system", MIRRMNT(system));
VLOGI("link", MIRRMNT(system_root) "/system", MIRRMNT(system));
system_as_root = true;
} else if (!system_as_root && str_contains(line, " /system ")) {
mount_mirror(system, MS_RDONLY);
} else if (str_contains(line, " /vendor ")) {
mount_mirror(vendor, MS_RDONLY);
seperate_vendor = true;
} else if (str_contains(line, " /data ")) {
mount_mirror(data, 0);
} else if (SDK_INT >= 24 &&
@ -379,9 +383,9 @@ static bool magisk_env() {
}
return true;
});
if (!seperate_vendor) {
xsymlink(MIRRDIR "/system/vendor", MIRRDIR "/vendor");
VLOGI("link", MIRRDIR "/system/vendor", MIRRDIR "/vendor");
if (access(MIRRMNT(vendor), F_OK) != 0) {
xsymlink(MIRRMNT(system) "/vendor", MIRRMNT(vendor));
VLOGI("link", MIRRMNT(system) "/vendor", MIRRMNT(vendor));
}
// Disable/remove magiskhide, resetprop, and modules
@ -622,9 +626,6 @@ void post_fs_data(int client) {
// Create the system root entry
auto sys_root = new node_entry("system", IS_INTER);
// Vendor root entry
node_entry *ven_root = nullptr;
bool has_modules = false;
LOGI("* Loading modules\n");
@ -659,17 +660,18 @@ void post_fs_data(int client) {
}
if (has_modules) {
// Pull out /system/vendor node if exist
ven_root = sys_root->extract("vendor");
// Pull out special nodes if exist
node_entry *special;
if ((special = sys_root->extract("vendor"))) {
special->magic_mount();
delete special;
}
// Magic!!
sys_root->magic_mount();
if (ven_root) ven_root->magic_mount();
}
// Cleanup memory
delete sys_root;
delete ven_root;
core_only();
}