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Make sure patch_rootdir does not cause crashes

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topjohnwu 2020-12-06 02:19:57 -08:00
parent 2a694596b5
commit ae0d605310
1 changed files with 31 additions and 29 deletions
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38
native/jni/init/rootdir.cpp
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@ -189,39 +189,40 @@ static void magic_mount(const string &sdir, const string &ddir = "") {
#define NEW_INITRC "/system/etc/init/hw/init.rc"
void SARBase::patch_rootdir() {
char tmp_dir[32];
string tmp_dir;
const char *sepol;
char *p;
if (access("/sbin", F_OK) == 0) {
p = tmp_dir + sprintf(tmp_dir, "%s", "/sbin");
tmp_dir = "/sbin";
sepol = "/sbin/.se";
} else {
p = tmp_dir + sprintf(tmp_dir, "%s", "/dev/");
p += gen_rand_str(p, 8);
xmkdir(tmp_dir, 0);
char buf[8];
gen_rand_str(buf, sizeof(buf));
tmp_dir = "/dev/"s + buf;
xmkdir(tmp_dir.data(), 0);
sepol = "/dev/.se";
}
setup_tmp(tmp_dir);
chdir(tmp_dir);
setup_tmp(tmp_dir.data());
chdir(tmp_dir.data());
mount_rules_dir(BLOCKDIR, MIRRDIR);
// Mount system_root mirror
xmkdir(ROOTMIR, 0755);
xmount("/", ROOTMIR, nullptr, MS_BIND, nullptr);
strcpy(p, "/" ROOTMIR);
mount_list.emplace_back(tmp_dir);
*p = '\0';
mount_list.emplace_back(tmp_dir + "/" ROOTMIR);
// Recreate original sbin structure if necessary
if (tmp_dir == "/sbin"sv)
if (tmp_dir == "/sbin")
recreate_sbin(ROOTMIR "/sbin", true);
// Patch init
int patch_count;
{
int src = xopen("/init", O_RDONLY | O_CLOEXEC);
auto init = raw_data::read(src);
int patch_count = init.patch({
patch_count = init.patch({
make_pair(SPLIT_PLAT_CIL, "xxx"), /* Force loading monolithic sepolicy */
make_pair(MONOPOLICY, sepol) /* Redirect /sepolicy to custom path */
});
@ -231,13 +232,14 @@ void SARBase::patch_rootdir() {
fclone_attr(src, dest);
close(src);
close(dest);
}
if (patch_count != 2 && access(LIBSELINUX, F_OK) == 0) {
// init is dynamically linked, need to patch libselinux
auto lib = raw_data::read(LIBSELINUX);
lib.patch({make_pair(MONOPOLICY, sepol)});
xmkdirs(dirname(ROOTOVL LIBSELINUX), 0755);
dest = xopen(ROOTOVL LIBSELINUX, O_CREAT | O_WRONLY | O_CLOEXEC, 0);
int dest = xopen(ROOTOVL LIBSELINUX, O_CREAT | O_WRONLY | O_CLOEXEC, 0);
xwrite(dest, lib.buf, lib.sz);
close(dest);
clone_attr(LIBSELINUX, ROOTOVL LIBSELINUX);
@ -252,7 +254,7 @@ void SARBase::patch_rootdir() {
if (connect(sockfd, (struct sockaddr*) &sun, setup_sockaddr(&sun, INIT_SOCKET)) == 0) {
LOGD("ACK init daemon to write backup files\n");
// Let daemon know where tmp_dir is
write_string(sockfd, tmp_dir);
write_string(sockfd, tmp_dir.data());
// Wait for daemon to finish restoring files
int ack;
read(sockfd, &ack, sizeof(ack));
@ -272,16 +274,16 @@ void SARBase::patch_rootdir() {
// Patch init.rc
if (access("/init.rc", F_OK) == 0) {
patch_init_rc("/init.rc", ROOTOVL "/init.rc", tmp_dir);
patch_init_rc("/init.rc", ROOTOVL "/init.rc", tmp_dir.data());
} else {
// Android 11's new init.rc
xmkdirs(dirname(ROOTOVL NEW_INITRC), 0755);
patch_init_rc(NEW_INITRC, ROOTOVL NEW_INITRC, tmp_dir);
patch_init_rc(NEW_INITRC, ROOTOVL NEW_INITRC, tmp_dir.data());
}
// Mount rootdir
magic_mount(ROOTOVL);
dest = xopen(ROOTMNT, O_WRONLY | O_CREAT | O_CLOEXEC, 0);
int dest = xopen(ROOTMNT, O_WRONLY | O_CREAT | O_CLOEXEC, 0);
write(dest, magic_mount_list.data(), magic_mount_list.length());
close(dest);