mirror of
https://github.com/topjohnwu/Magisk.git
synced 2025-12-03 12:11:54 +00:00
Boot MagiskInit as actual system-as-root
WIP, no customization. DO NOT USE YET!
This commit is contained in:
topjohnwu
259
native/jni/init/rootdir.cpp
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259
native/jni/init/rootdir.cpp
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <sys/mount.h>
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#include <fcntl.h>
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#include <magisk.h>
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#include <utils.h>
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#include "init.h"
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#include "flags.h"
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#include "magiskrc.h"
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#ifdef USE_64BIT
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#define LIBNAME "lib64"
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#else
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#define LIBNAME "lib"
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#endif
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using namespace std;
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static void patch_socket_name(const char *path) {
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uint8_t *buf;
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char name[sizeof(MAIN_SOCKET)];
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size_t size;
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mmap_rw(path, buf, size);
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for (int i = 0; i < size; ++i) {
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if (memcmp(buf + i, MAIN_SOCKET, sizeof(MAIN_SOCKET)) == 0) {
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gen_rand_str(name, sizeof(name));
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memcpy(buf + i, name, sizeof(name));
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i += sizeof(name);
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}
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}
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munmap(buf, size);
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}
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constexpr const char wrapper[] =
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"#!/system/bin/sh\n"
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"export LD_LIBRARY_PATH=\"$LD_LIBRARY_PATH:/apex/com.android.runtime/" LIBNAME "\"\n"
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"exec /sbin/magisk.bin \"$0\" \"$@\"\n"
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;
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void RootFSInit::setup_rootfs() {
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bool patch_init = patch_sepolicy();
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if (cmd->system_as_root) {
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// Clone rootfs
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LOGD("Clone root dir from system to rootfs\n");
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int system_root = xopen("/system_root", O_RDONLY | O_CLOEXEC);
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clone_dir(system_root, root, false);
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close(system_root);
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}
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if (patch_init) {
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constexpr char SYSTEM_INIT[] = "/system/bin/init";
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// If init is symlink, copy it to rootfs so we can patch
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if (is_lnk("/init"))
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cp_afc(SYSTEM_INIT, "/init");
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char *addr;
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size_t size;
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mmap_rw("/init", addr, size);
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for (char *p = addr; p < addr + size; ++p) {
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if (memcmp(p, SPLIT_PLAT_CIL, sizeof(SPLIT_PLAT_CIL)) == 0) {
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// Force init to load /sepolicy
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LOGD("Remove from init: " SPLIT_PLAT_CIL "\n");
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memset(p, 'x', sizeof(SPLIT_PLAT_CIL) - 1);
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p += sizeof(SPLIT_PLAT_CIL) - 1;
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} else if (memcmp(p, SYSTEM_INIT, sizeof(SYSTEM_INIT)) == 0) {
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// Force execute /init instead of /system/bin/init
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LOGD("Patch init: [/system/bin/init] -> [/init]\n");
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strcpy(p, "/init");
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p += sizeof(SYSTEM_INIT) - 1;
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}
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}
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munmap(addr, size);
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}
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// Handle ramdisk overlays
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int fd = open("/overlay", O_RDONLY | O_CLOEXEC);
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if (fd >= 0) {
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LOGD("Merge overlay folder\n");
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mv_dir(fd, root);
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close(fd);
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rmdir("/overlay");
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}
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// Patch init.rc
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FILE *rc = xfopen("/init.p.rc", "we");
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file_readline("/init.rc", [&](auto line) -> bool {
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// Do not start vaultkeeper
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if (str_contains(line, "start vaultkeeper")) {
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LOGD("Remove vaultkeeper\n");
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return true;
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}
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// Do not run flash_recovery
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if (str_starts(line, "service flash_recovery")) {
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LOGD("Remove flash_recovery\n");
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fprintf(rc, "service flash_recovery /system/bin/xxxxx\n");
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return true;
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}
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// Else just write the line
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fprintf(rc, "%s", line.data());
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return true;
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});
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char pfd_svc[8], ls_svc[8], bc_svc[8];
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// Make sure to be unique
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pfd_svc[0] = 'a';
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ls_svc[0] = '0';
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bc_svc[0] = 'A';
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gen_rand_str(pfd_svc + 1, sizeof(pfd_svc) - 1);
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gen_rand_str(ls_svc + 1, sizeof(ls_svc) - 1);
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gen_rand_str(bc_svc + 1, sizeof(bc_svc) - 1);
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LOGD("Inject magisk services: [%s] [%s] [%s]\n", pfd_svc, ls_svc, bc_svc);
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fprintf(rc, magiskrc, pfd_svc, pfd_svc, ls_svc, bc_svc, bc_svc);
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fclose(rc);
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clone_attr("/init.rc", "/init.p.rc");
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rename("/init.p.rc", "/init.rc");
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// Don't let init run in init yet
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lsetfilecon("/init", "u:object_r:rootfs:s0");
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// Create hardlink mirror of /sbin to /root
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mkdir("/root", 0750);
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clone_attr("/sbin", "/root");
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int rootdir = xopen("/root", O_RDONLY | O_CLOEXEC);
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int sbin = xopen("/sbin", O_RDONLY | O_CLOEXEC);
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link_dir(sbin, rootdir);
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close(sbin);
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// Dump magiskinit as magisk
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fd = xopen("/sbin/magisk", O_WRONLY | O_CREAT, 0755);
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write(fd, self.buf, self.sz);
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close(fd);
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}
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bool MagiskInit::patch_sepolicy() {
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bool patch_init = false;
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if (access(SPLIT_PLAT_CIL, R_OK) == 0) {
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LOGD("sepol: split policy\n");
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patch_init = true;
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} else if (access("/sepolicy", R_OK) == 0) {
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LOGD("sepol: monolithic policy\n");
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load_policydb("/sepolicy");
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} else {
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LOGD("sepol: no selinux\n");
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return false;
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}
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// Mount selinuxfs to communicate with kernel
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xmount("selinuxfs", SELINUX_MNT, "selinuxfs", 0, nullptr);
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if (patch_init)
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load_split_cil();
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sepol_magisk_rules();
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sepol_allow(SEPOL_PROC_DOMAIN, ALL, ALL, ALL);
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dump_policydb("/sepolicy");
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// Load policy to kernel so we can label rootfs
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if (load_sepol) {
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LOGD("sepol: preload sepolicy\n");
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dump_policydb(SELINUX_LOAD);
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}
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// Remove OnePlus stupid debug sepolicy and use our own
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if (access("/sepolicy_debug", F_OK) == 0) {
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unlink("/sepolicy_debug");
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link("/sepolicy", "/sepolicy_debug");
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}
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// Enable selinux functions
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selinux_builtin_impl();
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return patch_init;
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}
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#ifdef MAGISK_DEBUG
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static FILE *kmsg;
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static int vprintk(const char *fmt, va_list ap) {
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fprintf(kmsg, "magiskinit: ");
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return vfprintf(kmsg, fmt, ap);
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}
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static void setup_klog() {
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int fd = xopen("/proc/kmsg", O_WRONLY | O_CLOEXEC);
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kmsg = fdopen(fd, "w");
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setbuf(kmsg, nullptr);
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log_cb.d = log_cb.i = log_cb.w = log_cb.e = vprintk;
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log_cb.ex = nop_ex;
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}
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#else
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#define setup_klog(...)
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#endif
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int magisk_proxy_main(int argc, char *argv[]) {
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setup_klog();
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raw_data config;
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raw_data self;
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full_read("/sbin/magisk", &self.buf, &self.sz);
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full_read("/.backup/.magisk", &config.buf, &config.sz);
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xmount(nullptr, "/", nullptr, MS_REMOUNT, nullptr);
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unlink("/sbin/magisk");
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rm_rf("/.backup");
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LOGD("Mount /sbin tmpfs overlay\n");
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xmount("tmpfs", "/sbin", "tmpfs", 0, "mode=755");
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int sbin = xopen("/sbin", O_RDONLY | O_CLOEXEC);
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char path[64];
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// Create symlinks pointing back to /root
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{
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unique_ptr<DIR, decltype(&closedir)> dir(xopendir("/root"), &closedir);
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struct dirent *entry;
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while((entry = xreaddir(dir.get()))) {
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if (entry->d_name == "."sv || entry->d_name == ".."sv)
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continue;
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sprintf(path, "/root/%s", entry->d_name);
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xsymlinkat(path, sbin, entry->d_name);
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}
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}
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// Dump binaries
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mkdir(MAGISKTMP, 0755);
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int fd = xopen(MAGISKTMP "/config", O_WRONLY | O_CREAT, 0000);
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write(fd, config.buf, config.sz);
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close(fd);
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fd = xopen("/sbin/magiskinit", O_WRONLY | O_CREAT, 0755);
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write(fd, self.buf, self.sz);
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close(fd);
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if (access("/system/apex", F_OK) == 0) {
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LOGD("APEX detected, use wrapper\n");
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dump_magisk("/sbin/magisk.bin", 0755);
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patch_socket_name("/sbin/magisk.bin");
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fd = xopen("/sbin/magisk", O_WRONLY | O_CREAT, 0755);
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write(fd, wrapper, sizeof(wrapper) - 1);
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close(fd);
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} else {
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dump_magisk("/sbin/magisk", 0755);
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patch_socket_name("/sbin/magisk");
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}
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// Create applet symlinks
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for (int i = 0; applet_names[i]; ++i) {
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sprintf(path, "/sbin/%s", applet_names[i]);
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xsymlink("/sbin/magisk", path);
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}
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xsymlink("/sbin/magiskinit", "/sbin/magiskpolicy");
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xsymlink("/sbin/magiskinit", "/sbin/supolicy");
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setenv("REMOUNT_ROOT", "1", 1);
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execv("/sbin/magisk", argv);
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return 1;
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}
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