2017-11-05 22:41:03 +01:00
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/* magiskinit.c - Pre-init Magisk support
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*
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* This code has to be compiled statically to work properly.
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*
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2017-11-09 17:54:54 +01:00
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* To unify Magisk support for both legacy "normal" devices and new skip_initramfs devices,
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* magisk binary compilation is split into two parts - first part only compiles "magisk".
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* The python build script will load the magisk main binary and compress with lzma2, dumping
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* the results into "dump.h". The "magisk" binary is embedded into this binary, and will
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* get extracted to the overlay folder along with init.magisk.rc.
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*
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* This tool does all pre-init operations to setup a Magisk environment, which pathces rootfs
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* on the fly, providing fundamental support such as init, init.rc, and sepolicy patching.
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*
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* Magiskinit is also responsible for constructing a proper rootfs on skip_initramfs devices.
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2017-11-05 22:41:03 +01:00
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* On skip_initramfs devices, it will parse kernel cmdline, mount sysfs, parse through
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* uevent files to make the system (or vendor if available) block device node, then copy
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2017-11-09 17:54:54 +01:00
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* rootfs files from system.
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*
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2017-11-05 22:41:03 +01:00
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* This tool will be replaced with the real init to continue the boot process, but hardlinks are
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* preserved as it also provides CLI for sepolicy patching (magiskpolicy)
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <string.h>
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#include <dirent.h>
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#include <fcntl.h>
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#include <libgen.h>
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#include <sys/stat.h>
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#include <sys/types.h>
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#include <sys/mount.h>
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#include <sys/mman.h>
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#include <sys/sendfile.h>
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#include <sys/sysmacros.h>
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2017-11-09 17:54:54 +01:00
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#include <lzma.h>
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2017-11-05 22:41:03 +01:00
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#include <cil/cil.h>
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#include "magisk.h"
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#include "utils.h"
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#include "magiskpolicy.h"
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2017-11-09 17:54:54 +01:00
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#include "magiskrc.h"
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#include "dump.h"
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2017-11-05 22:41:03 +01:00
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2017-11-06 15:33:41 +01:00
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// #define VLOG(fmt, ...) printf(fmt, __VA_ARGS__) /* Enable to debug */
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#define VLOG(fmt, ...)
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2017-11-05 22:41:03 +01:00
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struct cmdline {
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int skip_initramfs;
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char slot[3];
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};
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struct device {
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dev_t major;
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dev_t minor;
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char devname[32];
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char partname[32];
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char path[64];
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};
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extern policydb_t *policydb;
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static void parse_cmdline(struct cmdline *cmd) {
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char *tok;
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char buffer[4096];
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mkdir("/proc", 0555);
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mount("proc", "/proc", "proc", 0, NULL);
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int fd = open("/proc/cmdline", O_RDONLY | O_CLOEXEC);
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ssize_t size = read(fd, buffer, sizeof(buffer));
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buffer[size] = '\0';
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close(fd);
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umount("/proc");
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tok = strtok(buffer, " ");
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cmd->skip_initramfs = 0;
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cmd->slot[0] = '\0';
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while (tok != NULL) {
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if (strncmp(tok, "androidboot.slot_suffix", 23) == 0) {
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sscanf(tok, "androidboot.slot_suffix=%s", cmd->slot);
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2017-11-06 15:33:41 +01:00
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} else if (strncmp(tok, "androidboot.slot", 16) == 0) {
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cmd->slot[0] = '_';
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sscanf(tok, "androidboot.slot=%s", cmd->slot + 1);
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2017-11-05 22:41:03 +01:00
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} else if (strcmp(tok, "skip_initramfs") == 0) {
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cmd->skip_initramfs = 1;
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}
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tok = strtok(NULL, " ");
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}
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}
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static void parse_device(struct device *dev, char *uevent) {
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2017-11-06 15:33:41 +01:00
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dev->partname[0] = '\0';
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2017-11-05 22:41:03 +01:00
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char *tok;
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tok = strtok(uevent, "\n");
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while (tok != NULL) {
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if (strncmp(tok, "MAJOR", 5) == 0) {
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sscanf(tok, "MAJOR=%ld", (long*) &dev->major);
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} else if (strncmp(tok, "MINOR", 5) == 0) {
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sscanf(tok, "MINOR=%ld", (long*) &dev->minor);
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} else if (strncmp(tok, "DEVNAME", 7) == 0) {
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sscanf(tok, "DEVNAME=%s", dev->devname);
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} else if (strncmp(tok, "PARTNAME", 8) == 0) {
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sscanf(tok, "PARTNAME=%s", dev->partname);
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}
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tok = strtok(NULL, "\n");
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}
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2017-11-06 15:33:41 +01:00
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VLOG("%s [%s] (%u, %u)\n", dev->devname, dev->partname, (unsigned) dev->major, (unsigned) dev->minor);
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2017-11-05 22:41:03 +01:00
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}
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static int setup_block(struct device *dev, const char *partname) {
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char buffer[1024], path[128];
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struct dirent *entry;
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DIR *dir = opendir("/sys/dev/block");
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if (dir == NULL)
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return 1;
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int found = 0;
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while ((entry = readdir(dir))) {
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if (strcmp(entry->d_name, ".") == 0 || strcmp(entry->d_name, "..") == 0)
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continue;
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snprintf(path, sizeof(path), "/sys/dev/block/%s/uevent", entry->d_name);
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int fd = open(path, O_RDONLY | O_CLOEXEC);
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ssize_t size = read(fd, buffer, sizeof(buffer));
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buffer[size] = '\0';
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close(fd);
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parse_device(dev, buffer);
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if (strcmp(dev->partname, partname) == 0) {
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snprintf(dev->path, sizeof(dev->path), "/dev/block/%s", dev->devname);
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found = 1;
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break;
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}
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}
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closedir(dir);
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if (!found)
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return 1;
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mkdir("/dev", 0755);
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mkdir("/dev/block", 0755);
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mknod(dev->path, S_IFBLK | 0600, makedev(dev->major, dev->minor));
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return 0;
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}
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static void *patch_init_rc(char *data, uint32_t *size) {
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int injected = 0;
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char *new_data = malloc(*size + 23);
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char *old_data = data;
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uint32_t pos = 0;
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for (char *tok = strsep(&old_data, "\n"); tok; tok = strsep(&old_data, "\n")) {
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if (!injected && strncmp(tok, "import", 6) == 0) {
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if (strstr(tok, "init.magisk.rc")) {
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injected = 1;
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} else {
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strcpy(new_data + pos, "import /init.magisk.rc\n");
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pos += 23;
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injected = 1;
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}
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} else if (strstr(tok, "selinux.reload_policy")) {
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continue;
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}
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// Copy the line
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strcpy(new_data + pos, tok);
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pos += strlen(tok);
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new_data[pos++] = '\n';
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}
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*size = pos;
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return new_data;
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}
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static void patch_ramdisk() {
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void *addr;
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size_t size;
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mmap_rw("/init", &addr, &size);
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for (int i = 0; i < size; ++i) {
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if (memcmp(addr + i, "/system/etc/selinux/plat_sepolicy.cil", 37) == 0) {
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memcpy(addr + i, "/system/etc/selinux/plat_sepolicy.xxx", 37);
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break;
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}
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}
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munmap(addr, size);
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mmap_rw("/init.rc", &addr, &size);
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uint32_t new_size = size;
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void *init_rc = patch_init_rc(addr, &new_size);
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munmap(addr, size);
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int fd = open("/init.rc", O_WRONLY | O_TRUNC | O_CLOEXEC);
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write(fd, init_rc, new_size);
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close(fd);
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free(init_rc);
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}
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static int strend(const char *s1, const char *s2) {
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int l1 = strlen(s1);
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int l2 = strlen(s2);
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return strcmp(s1 + l1 - l2, s2);
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}
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static int compile_cil() {
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DIR *dir;
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struct dirent *entry;
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char path[128];
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struct cil_db *db = NULL;
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sepol_policydb_t *pdb = NULL;
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void *addr;
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size_t size;
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cil_db_init(&db);
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cil_set_mls(db, 1);
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cil_set_target_platform(db, SEPOL_TARGET_SELINUX);
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cil_set_policy_version(db, POLICYDB_VERSION_XPERMS_IOCTL);
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cil_set_attrs_expand_generated(db, 0);
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// plat
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mmap_ro("/system/etc/selinux/plat_sepolicy.cil", &addr, &size);
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cil_add_file(db, "/system/etc/selinux/plat_sepolicy.cil", addr, size);
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munmap(addr, size);
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// mapping
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char plat[10];
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int fd = open("/vendor/etc/selinux/plat_sepolicy_vers.txt", O_RDONLY | O_CLOEXEC);
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if (fd > 0) {
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plat[read(fd, plat, sizeof(plat)) - 1] = '\0';
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snprintf(path, sizeof(path), "/system/etc/selinux/mapping/%s.cil", plat);
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mmap_ro(path, &addr, &size);
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cil_add_file(db, path, addr, size);
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munmap(addr, size);
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close(fd);
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}
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dir = opendir("/vendor/etc/selinux");
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while ((entry = readdir(dir))) {
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if (strcmp(entry->d_name, ".") == 0 || strcmp(entry->d_name, "..") == 0)
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continue;
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if (strend(entry->d_name, ".cil") == 0) {
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snprintf(path, sizeof(path), "/vendor/etc/selinux/%s", entry->d_name);
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mmap_ro(path, &addr, &size);
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cil_add_file(db, path, addr, size);
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munmap(addr, size);
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}
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}
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closedir(dir);
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cil_compile(db);
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cil_build_policydb(db, &pdb);
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cil_db_destroy(&db);
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policydb = &pdb->p;
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return 0;
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}
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static int verify_precompiled() {
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DIR *dir;
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struct dirent *entry;
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int fd;
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char sys_sha[70], ven_sha[70];
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dir = opendir("/vendor/etc/selinux");
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while ((entry = readdir(dir))) {
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if (strcmp(entry->d_name, ".") == 0 || strcmp(entry->d_name, "..") == 0)
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continue;
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if (strend(entry->d_name, ".sha256") == 0) {
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fd = openat(dirfd(dir), entry->d_name, O_RDONLY | O_CLOEXEC);
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ven_sha[read(fd, ven_sha, sizeof(ven_sha))] = '\0';
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close(fd);
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break;
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}
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}
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closedir(dir);
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dir = opendir("/system/etc/selinux");
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while ((entry = readdir(dir))) {
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if (strcmp(entry->d_name, ".") == 0 || strcmp(entry->d_name, "..") == 0)
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continue;
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if (strend(entry->d_name, ".sha256") == 0) {
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fd = openat(dirfd(dir), entry->d_name, O_RDONLY | O_CLOEXEC);
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sys_sha[read(fd, sys_sha, sizeof(sys_sha))] = '\0';
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close(fd);
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break;
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}
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}
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closedir(dir);
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return strcmp(sys_sha, ven_sha);
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}
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static void patch_sepolicy() {
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if (access("/sepolicy", R_OK) == 0) {
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load_policydb("/sepolicy");
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} else if (access("/vendor/etc/selinux/precompiled_sepolicy", R_OK) == 0
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&& verify_precompiled() == 0) {
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load_policydb("/vendor/etc/selinux/precompiled_sepolicy");
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} else if (access("/system/etc/selinux/plat_sepolicy.cil", R_OK) == 0) {
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compile_cil();
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}
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sepol_med_rules();
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dump_policydb("/sepolicy");
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}
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2017-11-09 17:54:54 +01:00
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#define BUFSIZE (1 << 20)
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static int unxz(const void *buf, size_t size, int fd) {
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lzma_stream strm = LZMA_STREAM_INIT;
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if (lzma_auto_decoder(&strm, UINT64_MAX, 0) != LZMA_OK)
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return 1;
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lzma_ret ret = 0;
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void *out = malloc(BUFSIZE);
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strm.next_in = buf;
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strm.avail_in = size;
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do {
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strm.next_out = out;
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strm.avail_out = BUFSIZE;
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ret = lzma_code(&strm, LZMA_RUN);
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write(fd, out, BUFSIZE - strm.avail_out);
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} while (strm.avail_out == 0 && ret == LZMA_OK);
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free(out);
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lzma_end(&strm);
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if (ret != LZMA_OK && ret != LZMA_STREAM_END)
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return 1;
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return 0;
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}
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static int dump_magisk(const char *path, mode_t mode) {
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unlink(path);
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int fd = creat(path, mode);
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int ret = unxz(magisk_dump, sizeof(magisk_dump), fd);
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close(fd);
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return ret;
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}
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static int dump_magiskrc(const char *path, mode_t mode) {
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int fd = creat(path, mode);
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write(fd, magiskrc, sizeof(magiskrc));
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close(fd);
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return 0;
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}
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2017-11-05 22:41:03 +01:00
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int main(int argc, char *argv[]) {
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|
if (strcmp(basename(argv[0]), "magiskpolicy") == 0 || strcmp(basename(argv[0]), "supolicy") == 0)
|
|
|
|
return magiskpolicy_main(argc, argv);
|
|
|
|
if (argc > 1 && (strcmp(argv[1], "magiskpolicy") == 0 || strcmp(argv[1], "supolicy") == 0))
|
|
|
|
return magiskpolicy_main(argc - 1, argv + 1);
|
|
|
|
|
|
|
|
umask(0);
|
|
|
|
|
2017-11-09 17:54:54 +01:00
|
|
|
if (argc > 1) {
|
|
|
|
if (strcmp(argv[2], "magisk") == 0)
|
|
|
|
return dump_magisk(argv[3], 0755);
|
|
|
|
else if (strcmp(argv[2], "magiskrc") == 0)
|
|
|
|
return dump_magiskrc(argv[3], 0755);
|
|
|
|
}
|
|
|
|
|
|
|
|
// Extract and link files
|
|
|
|
mkdir("/overlay", 0000);
|
|
|
|
dump_magiskrc("/overlay/init.magisk.rc", 0750);
|
|
|
|
mkdir("/overlay/sbin", 0755);
|
|
|
|
dump_magisk("/overlay/sbin/magisk", 0755);
|
|
|
|
mkdir("/overlay/root", 0755);
|
|
|
|
link("/init", "/overlay/root/magiskinit");
|
|
|
|
symlink("/root/magiskinit", "/overlay/root/magiskpolicy");
|
|
|
|
symlink("/root/magiskinit", "/overlay/root/supolicy");
|
|
|
|
|
2017-11-05 22:41:03 +01:00
|
|
|
struct cmdline cmd;
|
|
|
|
parse_cmdline(&cmd);
|
|
|
|
|
2017-11-06 15:33:41 +01:00
|
|
|
VLOG("cmdline: skip_initramfs=[%d] slot_suffix=[%s]\n", cmd.skip_initramfs, cmd.slot);
|
|
|
|
|
2017-11-05 22:41:03 +01:00
|
|
|
int root = open("/", O_RDONLY | O_CLOEXEC);
|
|
|
|
|
|
|
|
if (cmd.skip_initramfs) {
|
|
|
|
// Exclude overlay folder
|
|
|
|
excl_list = (char *[]) { "overlay", ".backup", NULL };
|
|
|
|
// Clear rootfs
|
|
|
|
frm_rf(root);
|
|
|
|
|
|
|
|
mkdir("/sys", 0755);
|
|
|
|
mount("sysfs", "/sys", "sysfs", 0, NULL);
|
|
|
|
|
|
|
|
char partname[32];
|
|
|
|
snprintf(partname, sizeof(partname), "system%s", cmd.slot);
|
|
|
|
|
|
|
|
struct device dev;
|
|
|
|
setup_block(&dev, partname);
|
|
|
|
|
|
|
|
mkdir("/system_root", 0755);
|
|
|
|
mount(dev.path, "/system_root", "ext4", MS_RDONLY, NULL);
|
|
|
|
int system_root = open("/system_root", O_RDONLY | O_CLOEXEC);
|
|
|
|
|
|
|
|
// Exclude system folder
|
|
|
|
excl_list = (char *[]) { "system", NULL };
|
|
|
|
clone_dir(system_root, root);
|
|
|
|
mkdir("/system", 0755);
|
|
|
|
mount("/system_root/system", "/system", NULL, MS_BIND, NULL);
|
|
|
|
|
|
|
|
snprintf(partname, sizeof(partname), "vendor%s", cmd.slot);
|
|
|
|
|
|
|
|
// We need to mount independent vendor partition
|
|
|
|
if (setup_block(&dev, partname) == 0)
|
|
|
|
mount(dev.path, "/vendor", "ext4", MS_RDONLY, NULL);
|
|
|
|
|
|
|
|
close(system_root);
|
|
|
|
} else {
|
|
|
|
// Revert original init binary
|
|
|
|
unlink("/init");
|
|
|
|
link("/.backup/init", "/init");
|
|
|
|
}
|
|
|
|
|
|
|
|
int overlay = open("/overlay", O_RDONLY | O_CLOEXEC);
|
|
|
|
mv_dir(overlay, root);
|
|
|
|
|
|
|
|
patch_ramdisk();
|
|
|
|
patch_sepolicy();
|
|
|
|
|
|
|
|
// Clean up
|
|
|
|
rmdir("/overlay");
|
|
|
|
umount("/vendor");
|
|
|
|
close(overlay);
|
|
|
|
close(root);
|
|
|
|
|
|
|
|
if (fork() == 0) {
|
|
|
|
// Fork a new process for full patch
|
|
|
|
setsid();
|
|
|
|
sepol_allow("su", ALL, ALL, ALL);
|
2017-11-22 09:12:08 +01:00
|
|
|
while (access(PATCHSTART, W_OK) == -1)
|
2017-11-05 22:41:03 +01:00
|
|
|
usleep(500); /* Wait 0.5ms */
|
2017-11-22 09:12:08 +01:00
|
|
|
unlink(PATCHSTART);
|
2017-11-05 22:41:03 +01:00
|
|
|
dump_policydb(SELINUX_LOAD);
|
|
|
|
close(open(PATCHDONE, O_RDONLY | O_CREAT, 0));
|
|
|
|
destroy_policydb();
|
|
|
|
} else {
|
|
|
|
// Finally, give control back!
|
|
|
|
execv("/init", argv);
|
|
|
|
}
|
|
|
|
|
|
|
|
return 0;
|
|
|
|
}
|