Magisk/native/jni/magiskboot/ramdisk.cpp
topjohnwu e72c6685ed Support A only System-as-root Devices
Most Chinese devices (and supposedly Galaxy S10) running Android Pie
is using system-as-root without A/B partition.

https://source.android.com/devices/bootloader/system-as-root#about-system-as-root

According to the docs above, these devices will have a ramdisk block
with size 0 in their boot images. Since magiskinit can run independently
on system-as-root devices, we simply just create an empty ramdisk with
magiskinit added as init.

Huge thanks to @vvb2060 for the heads up and original PR.
Close #980, close #1102
2019-02-28 05:46:36 -05:00

328 lines
8.5 KiB
C++

#include <string.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <utils.h>
#include <cpio.h>
#include "magiskboot.h"
#include "compress.h"
using namespace std;
static const char *ramdisk_xz = "ramdisk.cpio.xz";
static const char *UNSUPPORT_LIST[] =
{ "sbin/launch_daemonsu.sh", "sbin/su", "init.xposed.rc",
"boot/sbin/launch_daemonsu.sh" };
static const char *MAGISK_LIST[] =
{ ".backup/.magisk", "init.magisk.rc",
"overlay/init.magisk.rc" };
class magisk_cpio : public cpio_rw {
public:
magisk_cpio() = default;
explicit magisk_cpio(const char *filename) : cpio_rw(filename) {}
void patch(bool keepverity, bool keepforceencrypt);
int test();
char *sha1();
void restore();
void backup(const char *orig);
void compress();
void decompress();
};
void magisk_cpio::patch(bool keepverity, bool keepforceencrypt) {
fprintf(stderr, "Patch with flag KEEPVERITY=[%s] KEEPFORCEENCRYPT=[%s]\n",
keepverity ? "true" : "false", keepforceencrypt ? "true" : "false");
auto next = entries.begin();
decltype(next) cur;
while (next != entries.end()) {
cur = next;
++next;
bool fstab = (!keepverity || !keepforceencrypt) &&
!str_starts(cur->first, ".backup") &&
str_contains(cur->first, "fstab") && S_ISREG(cur->second->mode);
if (!keepverity) {
if (fstab) {
patch_verity(&cur->second->data, &cur->second->filesize);
} else if (cur->first == "verity_key") {
rm(cur);
continue;
}
}
if (!keepforceencrypt) {
if (fstab) {
patch_encryption(&cur->second->data, &cur->second->filesize);
}
}
}
}
#define STOCK_BOOT 0
#define MAGISK_PATCHED 1 << 0
#define UNSUPPORTED_CPIO 1 << 1
#define COMPRESSED_CPIO 1 << 2
int magisk_cpio::test() {
if (exists(ramdisk_xz))
return MAGISK_PATCHED | COMPRESSED_CPIO;
for (auto file : UNSUPPORT_LIST)
if (exists(file))
return UNSUPPORTED_CPIO;
for (auto file : MAGISK_LIST)
if (exists(file))
return MAGISK_PATCHED;
return STOCK_BOOT;
}
#define for_each_line(line, buf, size) \
for (line = (char *) buf; line < (char *) buf + size && line[0]; line = strchr(line + 1, '\n') + 1)
char *magisk_cpio::sha1() {
char sha1[41];
char *line;
for (auto &e : entries) {
if (e.first == "init.magisk.rc" || e.first == "overlay/init.magisk.rc") {
for_each_line(line, e.second->data, e.second->filesize) {
if (strncmp(line, "#STOCKSHA1=", 11) == 0) {
strncpy(sha1, line + 12, 40);
sha1[40] = '\0';
return strdup(sha1);
}
}
} else if (e.first == ".backup/.magisk") {
for_each_line(line, e.second->data, e.second->filesize) {
if (strncmp(line, "SHA1=", 5) == 0) {
strncpy(sha1, line + 5, 40);
sha1[40] = '\0';
return strdup(sha1);
}
}
} else if (e.first == ".backup/.sha1") {
return (char *) e.second->data;
}
}
return nullptr;
}
#define for_each_str(str, buf, size) \
for (str = (char *) buf; str < (char *) buf + size; str = str += strlen(str) + 1)
void magisk_cpio::restore() {
decompress();
char *file;
auto next = entries.begin();
decltype(next) cur;
while (next != entries.end()) {
cur = next;
++next;
if (str_starts(cur->first, ".backup")) {
if (cur->first.length() == 7 || cur->first.substr(8) == ".magisk") {
rm(cur);
} else if (cur->first.substr(8) == ".rmlist") {
for_each_str(file, cur->second->data, cur->second->filesize)
rm(file, false);
rm(cur);
} else {
mv(cur, &cur->first[8]);
}
} else if (str_starts(cur->first, "overlay") ||
str_starts(cur->first, "magisk") ||
cur->first == "sbin/magic_mask.sh" ||
cur->first == "init.magisk.rc") {
// Some known stuff we can remove
rm(cur);
}
}
}
void magisk_cpio::backup(const char *orig) {
if (access(orig, R_OK))
return;
entry_map bkup_entries;
string remv;
auto b = new cpio_entry(".backup", S_IFDIR);
bkup_entries[b->filename].reset(b);
magisk_cpio o(orig);
// Remove possible backups in original ramdisk
o.rm(".backup", true);
rm(".backup", true);
auto lhs = o.entries.begin();
auto rhs = entries.begin();
while (lhs != o.entries.end() || rhs != entries.end()) {
int res;
bool backup = false;
if (lhs != o.entries.end() && rhs != entries.end()) {
res = lhs->first.compare(rhs->first);
} else if (lhs == o.entries.end()) {
res = 1;
} else if (rhs == entries.end()) {
res = -1;
}
if (res < 0) {
// Something is missing in new ramdisk, backup!
backup = true;
fprintf(stderr, "Backup missing entry: ");
} else if (res == 0) {
if (lhs->second->filesize != rhs->second->filesize ||
memcmp(lhs->second->data, rhs->second->data, lhs->second->filesize) != 0) {
// Not the same!
backup = true;
fprintf(stderr, "Backup mismatch entry: ");
}
} else {
// Something new in ramdisk
remv += rhs->first;
remv += (char) '\0';
fprintf(stderr, "Record new entry: [%s] -> [.backup/.rmlist]\n", rhs->first.data());
}
if (backup) {
string back_name(".backup/");
back_name += lhs->first;
fprintf(stderr, "[%s] -> [%s]\n", lhs->first.data(), back_name.data());
auto ex = static_cast<cpio_entry*>(lhs->second.release());
ex->filename = back_name;
bkup_entries[ex->filename].reset(ex);
}
// Increment positions
if (res < 0) {
++lhs;
} else if (res == 0) {
++lhs; ++rhs;
} else {
++rhs;
}
}
if (!remv.empty()) {
auto rmlist = new cpio_entry(".backup/.rmlist", S_IFREG);
rmlist->filesize = remv.length();
rmlist->data = xmalloc(remv.length());
memcpy(rmlist->data, remv.data(), remv.length());
bkup_entries[rmlist->filename].reset(rmlist);
}
if (bkup_entries.size() > 1)
entries.merge(bkup_entries);
}
void magisk_cpio::compress() {
if (exists(ramdisk_xz))
return;
fprintf(stderr, "Compressing cpio -> [%s]\n", ramdisk_xz);
auto init = entries.extract("init");
XZEncoder encoder;
encoder.set_out(make_unique<BufOutStream>());
output(encoder);
encoder.finalize();
auto backup = entries.extract(".backup");
auto config = entries.extract(".backup/.magisk");
entries.clear();
entries.insert(std::move(init));
entries.insert(std::move(backup));
entries.insert(std::move(config));
auto xz = new cpio_entry(ramdisk_xz, S_IFREG);
static_cast<BufOutStream *>(encoder.get_out())->release(xz->data, xz->filesize);
insert(xz);
}
void magisk_cpio::decompress() {
auto it = entries.find(ramdisk_xz);
if (it == entries.end())
return;
fprintf(stderr, "Decompressing cpio [%s]\n", ramdisk_xz);
entries.erase(".backup");
entries.erase(".backup/.magisk");
LZMADecoder decoder;
decoder.set_out(make_unique<BufOutStream>());
decoder.write(it->second->data, it->second->filesize);
decoder.finalize();
entries.erase(it);
char *buf;
size_t sz;
static_cast<BufOutStream *>(decoder.get_out())->getbuf(buf, sz);
load_cpio(buf, sz);
}
int cpio_commands(int argc, char *argv[]) {
char *incpio = argv[0];
++argv;
--argc;
magisk_cpio cpio;
if (access(incpio, R_OK) == 0)
cpio.load_cpio(incpio);
int cmdc;
char *cmdv[6];
while (argc) {
// Clean up
cmdc = 0;
memset(cmdv, NULL, sizeof(cmdv));
// Split the commands
for (char *tok = strtok(argv[0], " "); tok; tok = strtok(nullptr, " "))
cmdv[cmdc++] = tok;
if (cmdc == 0)
continue;
if (strcmp(cmdv[0], "test") == 0) {
exit(cpio.test());
} else if (strcmp(cmdv[0], "restore") == 0) {
cpio.restore();
} else if (strcmp(cmdv[0], "sha1") == 0) {
char *sha1 = cpio.sha1();
if (sha1) printf("%s\n", sha1);
return 0;
} else if (strcmp(cmdv[0], "compress") == 0){
cpio.compress();
} else if (strcmp(cmdv[0], "decompress") == 0){
cpio.decompress();
} else if (cmdc == 2 && strcmp(cmdv[0], "exists") == 0) {
exit(!cpio.exists(cmdv[1]));
} else if (cmdc == 2 && strcmp(cmdv[0], "backup") == 0) {
cpio.backup(cmdv[1]);
} else if (cmdc >= 2 && strcmp(cmdv[0], "rm") == 0) {
bool r = cmdc > 2 && strcmp(cmdv[1], "-r") == 0;
cpio.rm(cmdv[1 + r], r);
} else if (cmdc == 3 && strcmp(cmdv[0], "mv") == 0) {
cpio.mv(cmdv[1], cmdv[2]);
} else if (cmdc == 3 && strcmp(cmdv[0], "patch") == 0) {
cpio.patch(strcmp(cmdv[1], "true") == 0, strcmp(cmdv[2], "true") == 0);
} else if (strcmp(cmdv[0], "extract") == 0) {
if (cmdc == 3) {
return !cpio.extract(cmdv[1], cmdv[2]);
} else {
cpio.extract();
return 0;
}
} else if (cmdc == 3 && strcmp(cmdv[0], "mkdir") == 0) {
cpio.mkdir(strtoul(cmdv[1], nullptr, 8), cmdv[2]);
} else if (cmdc == 3 && strcmp(cmdv[0], "ln") == 0) {
cpio.ln(cmdv[1], cmdv[2]);
} else if (cmdc == 4 && strcmp(cmdv[0], "add") == 0) {
cpio.add(strtoul(cmdv[1], nullptr, 8), cmdv[2], cmdv[3]);
} else {
return 1;
}
--argc;
++argv;
}
cpio.dump(incpio);
return 0;
}