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Move sbin overlay creation to magiskinit

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This commit is contained in:
topjohnwu
2019-02-09 01:51:46 -05:00
parent 08e3405394
commit c8491d008f
8 changed files with 214 additions and 163 deletions
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159
native/jni/core/init.cpp
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@@ -42,6 +42,7 @@
#include "magiskrc.h"
#include "magisk.h"
#include "magiskpolicy.h"
#include "selinux.h"
#include "utils.h"
#include "flags.h"
@@ -49,10 +50,12 @@
int (*init_applet_main[]) (int, char *[]) = { magiskpolicy_main, magiskpolicy_main, nullptr };
static int root = -1;
static bool mnt_system = false;
static bool mnt_vendor = false;
static void *self, *config;
static size_t self_sz, config_sz;
struct cmdline {
bool early_boot;
char slot[3];
@@ -344,9 +347,104 @@ static void patch_socket_name(const char *path) {
munmap(buf, size);
}
static void setup_rc() {
// Patch init.rc to load magisk scripts
bool injected = false;
char line[4096];
FILE *fp = xfopen("/init.rc", "r");
int fd = open("/init.rc.new", O_WRONLY | O_CREAT | O_CLOEXEC, 0750);
while(fgets(line, sizeof(line), fp)) {
if (!injected && strncmp(line, "import", 6) == 0) {
if (strstr(line, "init.magisk.rc")) {
injected = true;
} else {
xwrite(fd, "import /init.magisk.rc\n", 23);
injected = true;
}
} else if (strstr(line, "selinux.reload_policy")) {
// Do not allow sepolicy patch
continue;
}
xwrite(fd, line, strlen(line));
}
fclose(fp);
close(fd);
rename("/init.rc.new", "/init.rc");
dump_magiskrc(MAGISKRC, 0750);
}
static const char wrapper[] =
"#!/system/bin/sh\n"
"unset LD_LIBRARY_PATH\n"
"unset LD_PRELOAD\n"
"exec /sbin/magisk.bin \"${0##*/}\" \"$@\"\n";
static void setup_overlay() {
char buf[128];
int fd;
while (access(EARLYINIT, F_OK) != 0)
usleep(10);
selinux_builtin_impl();
setcon("u:r:" SEPOL_PROC_DOMAIN ":s0");
unlink(EARLYINIT);
fd = open("/dev/null", O_RDWR);
xdup2(fd, STDIN_FILENO);
xdup2(fd, STDOUT_FILENO);
xdup2(fd, STDERR_FILENO);
// Mount the /sbin tmpfs overlay
xmount("tmpfs", "/sbin", "tmpfs", 0, nullptr);
chmod("/sbin", 0755);
setfilecon("/sbin", "u:object_r:rootfs:s0");
// Dump binaries
mkdir(MAGISKTMP, 0755);
fd = open(MAGISKTMP "/config", O_WRONLY | O_CREAT, 0000);
write(fd, config, config_sz);
close(fd);
fd = open("/sbin/magiskinit", O_WRONLY | O_CREAT, 0755);
write(fd, self, self_sz);
close(fd);
fd = open("/sbin/magisk", O_WRONLY | O_CREAT, 0755);
write(fd, wrapper, sizeof(wrapper));
close(fd);
dump_magisk("/sbin/magisk.bin", 0755);
patch_socket_name("/sbin/magisk.bin");
setfilecon("/sbin/magisk", "u:object_r:" SEPOL_FILE_DOMAIN ":s0");
setfilecon("/sbin/magisk.bin", "u:object_r:" SEPOL_FILE_DOMAIN ":s0");
setfilecon("/sbin/magiskinit", "u:object_r:" SEPOL_FILE_DOMAIN ":s0");
// Create applet symlinks
for (int i = 0; applet_names[i]; ++i) {
sprintf(buf, "/sbin/%s", applet_names[i]);
xsymlink("/sbin/magisk", buf);
}
for (int i = 0; init_applet[i]; ++i) {
sprintf(buf, "/sbin/%s", init_applet[i]);
xsymlink("/sbin/magiskinit", buf);
}
// Create symlinks pointing back to /root
DIR *dir;
struct dirent *entry;
dir = xopendir("/root");
fd = xopen("/sbin", O_RDONLY);
while((entry = xreaddir(dir))) {
if (strcmp(entry->d_name, ".") == 0 || strcmp(entry->d_name, "..") == 0) continue;
snprintf(buf, PATH_MAX, "/root/%s", entry->d_name);
xsymlinkat(buf, fd, entry->d_name);
}
closedir(dir);
close(fd);
close(xopen(EARLYINITDONE, O_RDONLY | O_CREAT, 0));
exit(0);
}
static void exec_init(char *argv[]) {
// Clean up
close(root);
umount("/proc");
umount("/sys");
if (mnt_system)
@@ -384,8 +482,9 @@ int main(int argc, char *argv[]) {
if (null > STDERR_FILENO)
close(null);
// Backup self
rename("/init", "/init.bak");
// Backup stuffs
full_read("/init", &self, &self_sz);
full_read("/.backup/.magisk", &config, &config_sz);
// Communicate with kernel using procfs and sysfs
mkdir("/proc", 0755);
@@ -400,25 +499,24 @@ int main(int argc, char *argv[]) {
* Initialize
* ***********/
int root, sbin;
root = open("/", O_RDONLY | O_CLOEXEC);
if (cmd.early_boot) {
// Clear rootfs
const char *excl[] = { "overlay", ".backup", "proc", "sys", "init.bak", nullptr };
const char *excl[] = { "overlay", "proc", "sys", nullptr };
excl_list = excl;
frm_rf(root);
excl_list = nullptr;
} else {
// Revert original init binary
link("/.backup/init", "/init");
rm_rf("/.backup");
}
// Do not go further if system_root device is booting as recovery
if (!cmd.early_boot && access("/sbin/recovery", F_OK) == 0) {
// Remove Magisk traces
rm_rf("/.backup");
if (!cmd.early_boot && access("/sbin/recovery", F_OK) == 0)
exec_init(argv);
}
/* ************
* Early Mount
@@ -467,38 +565,25 @@ int main(int argc, char *argv[]) {
close(fd);
rmdir("/overlay");
}
close(root);
// Patch init.rc to load magisk scripts
bool injected = false;
char line[4096];
FILE *fp = xfopen("/init.rc", "r");
fd = creat("/init.rc.new", 0750);
while(fgets(line, sizeof(line), fp)) {
if (!injected && strncmp(line, "import", 6) == 0) {
if (strstr(line, "init.magisk.rc")) {
injected = true;
} else {
xwrite(fd, "import /init.magisk.rc\n", 23);
injected = true;
}
} else if (strstr(line, "selinux.reload_policy")) {
// Do not allow sepolicy patch
continue;
}
xwrite(fd, line, strlen(line));
}
fclose(fp);
close(fd);
rename("/init.rc.new", "/init.rc");
// Create hardlink mirror of /sbin to /root
mkdir("/root", 0750);
clone_attr("/sbin", "/root");
root = xopen("/root", O_RDONLY | O_CLOEXEC);
sbin = xopen("/sbin", O_RDONLY | O_CLOEXEC);
link_dir(sbin, root);
// Patch sepolicy
setup_rc();
patch_sepolicy();
// Dump binaries
dump_magiskrc(MAGISKRC, 0750);
dump_magisk("/sbin/magisk", 0755);
patch_socket_name("/sbin/magisk");
rename("/init.bak", "/sbin/magiskinit");
// Close all file descriptors
for (int i = 0; i < 30; ++i)
close(i);
// Launch daemon to setup overlay
if (fork_dont_care() == 0)
setup_overlay();
exec_init(argv);
}