forked from MarcoBuster/Magisk
0ecfb63cd6
readlinkat() may return random value instead of the number of bytes placed in buf and crashing the system in two ways: 1. segmentation fault (buf[-7633350] = ‘\0’) 2. wrong link of watchdogd, resulting dog timeout Confirmed working in ZenFone 2 x86 series, may fix #2247 and #2356 Signed-off-by: Shaka Huang <shakalaca@gmail.com>
486 lines
13 KiB
C++
486 lines
13 KiB
C++
#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <vector>
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#include <magisk.h>
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#include <magiskpolicy.h>
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#include <utils.h>
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#include "init.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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char *buf;
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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(buf + i, 16);
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i += sizeof(MAIN_SOCKET);
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}
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}
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munmap(buf, size);
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}
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static vector<raw_data> rc_list;
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static void patch_init_rc(FILE *rc) {
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file_readline("/init.rc", [=](string_view 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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fprintf(rc, "\n");
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// Inject custom rc scripts
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for (auto &d : rc_list)
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fprintf(rc, "\n%s\n", d.buf);
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rc_list.clear();
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// Inject Magisk rc scripts
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char pfd_svc[16], ls_svc[16], bc_svc[16];
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gen_rand_str(pfd_svc, sizeof(pfd_svc));
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gen_rand_str(ls_svc, sizeof(ls_svc));
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gen_rand_str(bc_svc, sizeof(bc_svc));
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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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}
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static void load_overlay_rc(int dirfd) {
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// Do not allow overwrite init.rc
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unlinkat(dirfd, "init.rc", 0);
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DIR *dir = fdopendir(dirfd);
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for (dirent *entry; (entry = readdir(dir));) {
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if (strend(entry->d_name, ".rc") == 0) {
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LOGD("Found rc script [%s]\n", entry->d_name);
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int rc = xopenat(dirfd, entry->d_name, O_RDONLY | O_CLOEXEC);
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raw_data data;
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fd_full_read(rc, data.buf, data.sz);
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close(rc);
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rc_list.push_back(std::move(data));
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unlinkat(dirfd, entry->d_name, 0);
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}
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}
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rewinddir(dir);
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}
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void RootFSInit::setup_rootfs() {
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if (patch_sepolicy()) {
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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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break;
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}
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}
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munmap(addr, size);
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}
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// Handle overlays
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int fd = open("/overlay.d", O_RDONLY | O_CLOEXEC);
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if (fd >= 0) {
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LOGD("Merge overlay.d\n");
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load_overlay_rc(fd);
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mv_dir(fd, root);
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close(fd);
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rmdir("/overlay.d");
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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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patch_init_rc(rc);
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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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// 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(const char *file) {
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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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mount_list.emplace_back(SELINUX_MNT);
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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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// Custom rules
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if (auto dir = xopen_dir(persist_dir); dir) {
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char path[4096];
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for (dirent *entry; (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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snprintf(path, sizeof(path), "%s/%s/sepolicy.rule", persist_dir, entry->d_name);
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if (access(path, R_OK) == 0) {
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LOGD("Loading custom sepolicy patch: %s\n", path);
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load_rule_file(path);
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}
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}
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}
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dump_policydb(file);
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destroy_policydb();
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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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return patch_init;
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}
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static void sbin_overlay(const raw_data &self, const raw_data &config) {
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mount_sbin();
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// Dump binaries
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xmkdir(MAGISKTMP, 0755);
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int fd = xopen(MAGISKTMP "/config", O_WRONLY | O_CREAT, 0000);
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xwrite(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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xwrite(fd, self.buf, self.sz);
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close(fd);
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dump_magisk("/sbin/magisk", 0755);
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patch_socket_name("/sbin/magisk");
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// Create applet symlinks
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char path[64];
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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("./magisk", path);
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}
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xsymlink("./magiskinit", "/sbin/magiskpolicy");
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xsymlink("./magiskinit", "/sbin/supolicy");
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}
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static void recreate_sbin(const char *mirror, bool use_bind_mount) {
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auto dp = xopen_dir(mirror);
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int src = dirfd(dp.get());
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char buf[4096];
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for (dirent *entry; (entry = xreaddir(dp.get()));) {
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if (entry->d_name == "."sv || entry->d_name == ".."sv)
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continue;
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string sbin_path = "/sbin/"s + entry->d_name;
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struct stat st;
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fstatat(src, entry->d_name, &st, AT_SYMLINK_NOFOLLOW);
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if (S_ISLNK(st.st_mode)) {
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#if defined(__i386__)
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// readlinkat() may failed on x86 platform, returning random value
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// instead of number of bytes placed in buf (length of link)
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memset(buf, 0, sizeof(buf));
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readlinkat(src, entry->d_name, buf, sizeof(buf));
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#else
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xreadlinkat(src, entry->d_name, buf, sizeof(buf));
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#endif
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xsymlink(buf, sbin_path.data());
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} else {
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sprintf(buf, "%s/%s", mirror, entry->d_name);
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if (use_bind_mount) {
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auto mode = st.st_mode & 0777;
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// Create dummy
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if (S_ISDIR(st.st_mode))
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xmkdir(sbin_path.data(), mode);
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else
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close(xopen(sbin_path.data(), O_CREAT | O_WRONLY | O_CLOEXEC, mode));
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xmount(buf, sbin_path.data(), nullptr, MS_BIND, nullptr);
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} else {
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xsymlink(buf, sbin_path.data());
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}
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}
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}
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}
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#define ROOTMIR MIRRDIR "/system_root"
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#define ROOTBLK BLOCKDIR "/system_root"
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#define MONOPOLICY "/sepolicy"
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#define PATCHPOLICY "/sbin/.se"
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#define LIBSELINUX "/system/" LIBNAME "/libselinux.so"
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static string magic_mount_list;
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static void magic_mount(int dirfd, const string &path) {
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DIR *dir = xfdopendir(dirfd);
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for (dirent *entry; (entry = readdir(dir));) {
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if (entry->d_name == "."sv || entry->d_name == ".."sv)
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continue;
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string dest = path + "/" + entry->d_name;
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if (access(dest.data(), F_OK) == 0) {
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if (entry->d_type == DT_DIR) {
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// Recursive
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int fd = xopenat(dirfd, entry->d_name, O_RDONLY | O_CLOEXEC);
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magic_mount(fd, dest);
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close(fd);
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} else {
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string src = ROOTOVL + dest;
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LOGD("Mount [%s] -> [%s]\n", src.data(), dest.data());
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xmount(src.data(), dest.data(), nullptr, MS_BIND, nullptr);
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magic_mount_list += dest;
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magic_mount_list += '\n';
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}
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}
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}
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}
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void SARBase::patch_rootdir() {
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sbin_overlay(self, config);
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// Mount system_root mirror
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xmkdir(ROOTMIR, 0755);
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mknod(ROOTBLK, S_IFBLK | 0600, system_dev);
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if (xmount(ROOTBLK, ROOTMIR, "ext4", MS_RDONLY, nullptr))
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xmount(ROOTBLK, ROOTMIR, "erofs", MS_RDONLY, nullptr);
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// Recreate original sbin structure
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recreate_sbin(ROOTMIR "/sbin", true);
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// Patch init
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raw_data init;
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file_attr attr;
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bool redirect = false;
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int src = xopen("/init", O_RDONLY | O_CLOEXEC);
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fd_full_read(src, init.buf, init.sz);
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fgetattr(src, &attr);
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close(src);
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uint8_t *eof = init.buf + init.sz;
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for (uint8_t *p = init.buf; p < eof; ++p) {
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if (memcmp(p, SPLIT_PLAT_CIL, sizeof(SPLIT_PLAT_CIL)) == 0) {
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// Force init to load monolithic policy
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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, MONOPOLICY, sizeof(MONOPOLICY)) == 0) {
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// Redirect /sepolicy to tmpfs
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LOGD("Patch init [" MONOPOLICY "] -> [" PATCHPOLICY "]\n");
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memcpy(p, PATCHPOLICY, sizeof(PATCHPOLICY));
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redirect = true;
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p += sizeof(MONOPOLICY) - 1;
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}
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}
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xmkdir(ROOTOVL, 0);
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int dest = xopen(ROOTOVL "/init", O_CREAT | O_WRONLY | O_CLOEXEC);
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xwrite(dest, init.buf, init.sz);
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fsetattr(dest, &attr);
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close(dest);
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// Patch libselinux
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if (!redirect) {
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raw_data lib;
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// init is dynamically linked, need to patch libselinux
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full_read(LIBSELINUX, lib.buf, lib.sz);
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getattr(LIBSELINUX, &attr);
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eof = lib.buf + lib.sz;
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for (uint8_t *p = lib.buf; p < eof; ++p) {
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if (memcmp(p, MONOPOLICY, sizeof(MONOPOLICY)) == 0) {
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// Redirect /sepolicy to tmpfs
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LOGD("Patch libselinux.so [" MONOPOLICY "] -> [" PATCHPOLICY "]\n");
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memcpy(p, PATCHPOLICY, sizeof(PATCHPOLICY));
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break;
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}
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}
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xmkdir(ROOTOVL "/system", 0755);
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xmkdir(ROOTOVL "/system/" LIBNAME, 0755);
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dest = xopen(ROOTOVL LIBSELINUX, O_CREAT | O_WRONLY | O_CLOEXEC);
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xwrite(dest, lib.buf, lib.sz);
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fsetattr(dest, &attr);
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close(dest);
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}
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// sepolicy
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patch_sepolicy(PATCHPOLICY);
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// Handle overlay
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if ((src = xopen("/dev/overlay.d", O_RDONLY | O_CLOEXEC)) >= 0) {
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load_overlay_rc(src);
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if (int fd = xopen("/dev/overlay.d/sbin", O_RDONLY | O_CLOEXEC); fd >= 0) {
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dest = xopen("/sbin", O_RDONLY | O_CLOEXEC);
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clone_dir(fd, dest);
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close(fd);
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close(dest);
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xmkdir(ROOTOVL "/sbin", 0); // Prevent copying
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}
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dest = xopen(ROOTOVL, O_RDONLY | O_CLOEXEC);
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clone_dir(src, dest, false);
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rmdir(ROOTOVL "/sbin");
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close(src);
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close(dest);
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rm_rf("/dev/overlay.d");
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}
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// Patch init.rc
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FILE *rc = xfopen(ROOTOVL "/init.rc", "we");
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patch_init_rc(rc);
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fclose(rc);
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clone_attr("/init.rc", ROOTOVL "/init.rc");
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// Mount rootdir
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src = xopen(ROOTOVL, O_RDONLY | O_CLOEXEC);
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magic_mount(src, "");
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close(src);
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dest = xopen(ROOTMNT, O_WRONLY | O_CREAT | O_CLOEXEC);
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write(dest, magic_mount_list.data(), magic_mount_list.length());
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close(dest);
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}
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static void patch_fstab(const string &fstab) {
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string patched = fstab + ".p";
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FILE *fp = xfopen(patched.data(), "we");
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file_readline(fstab.data(), [=](string_view l) -> bool {
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if (l[0] == '#' || l.length() == 1)
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return true;
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char *line = (char *) l.data();
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int src0, src1, mnt0, mnt1, type0, type1, opt0, opt1, flag0, flag1;
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sscanf(line, "%n%*s%n %n%*s%n %n%*s%n %n%*s%n %n%*s%n",
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&src0, &src1, &mnt0, &mnt1, &type0, &type1, &opt0, &opt1, &flag0, &flag1);
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const char *src, *mnt, *type, *opt, *flag;
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src = &line[src0];
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line[src1] = '\0';
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mnt = &line[mnt0];
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line[mnt1] = '\0';
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type = &line[type0];
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line[type1] = '\0';
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opt = &line[opt0];
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line[opt1] = '\0';
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flag = &line[flag0];
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line[flag1] = '\0';
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// Redirect system to system_root
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if (mnt == "/system"sv)
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mnt = "/system_root";
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fprintf(fp, "%s %s %s %s %s\n", src, mnt, type, opt, flag);
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return true;
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});
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fclose(fp);
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// Replace old fstab
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clone_attr(fstab.data(), patched.data());
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rename(patched.data(), fstab.data());
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}
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#define FSR "/first_stage_ramdisk"
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void ABFirstStageInit::prepare() {
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// It is actually possible to NOT have FSR, create it just in case
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xmkdir(FSR, 0755);
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if (auto dir = xopen_dir(FSR); dir) {
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string fstab(FSR "/");
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for (dirent *de; (de = xreaddir(dir.get()));) {
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if (strstr(de->d_name, "fstab")) {
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fstab += de->d_name;
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break;
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}
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}
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if (fstab.length() == sizeof(FSR))
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return;
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patch_fstab(fstab);
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} else {
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return;
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}
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// Move stuffs for next stage
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xmkdir(FSR "/system", 0755);
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xmkdir(FSR "/system/bin", 0755);
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rename("/init", FSR "/system/bin/init");
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symlink("/system/bin/init", FSR "/init");
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xmkdir(FSR "/.backup", 0);
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rename("/.backup/.magisk", FSR "/.backup/.magisk");
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rename("/overlay.d", FSR "/overlay.d");
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}
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void AFirstStageInit::prepare() {
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auto dir = xopen_dir("/");
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for (dirent *de; (de = xreaddir(dir.get()));) {
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if (strstr(de->d_name, "fstab")) {
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patch_fstab(de->d_name);
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break;
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}
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}
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// Move stuffs for next stage
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xmkdir("/system", 0755);
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xmkdir("/system/bin", 0755);
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rename("/init", "/system/bin/init");
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rename("/.backup/init", "/init");
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}
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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;
|
|
|
|
full_read("/sbin/magisk", self.buf, self.sz);
|
|
full_read("/.backup/.magisk", config.buf, config.sz);
|
|
|
|
xmount(nullptr, "/", nullptr, MS_REMOUNT, nullptr);
|
|
|
|
unlink("/sbin/magisk");
|
|
rm_rf("/.backup");
|
|
|
|
sbin_overlay(self, config);
|
|
|
|
// Create symlinks pointing back to /root
|
|
recreate_sbin("/root", false);
|
|
|
|
setenv("REMOUNT_ROOT", "1", 1);
|
|
execv("/sbin/magisk", argv);
|
|
|
|
return 1;
|
|
}
|