mirror of
https://github.com/topjohnwu/Magisk.git
synced 2024-11-28 04:25:27 +00:00
383 lines
8.6 KiB
C++
383 lines
8.6 KiB
C++
#include <unistd.h>
|
|
#include <pthread.h>
|
|
#include <stdlib.h>
|
|
#include <fcntl.h>
|
|
#include <string.h>
|
|
#include <signal.h>
|
|
#include <pwd.h>
|
|
#include <sys/socket.h>
|
|
#include <sys/types.h>
|
|
#include <sys/stat.h>
|
|
#include <sys/wait.h>
|
|
|
|
#include "magisk.h"
|
|
#include "daemon.h"
|
|
#include "utils.h"
|
|
#include "su.h"
|
|
#include "pts.h"
|
|
#include "selinux.h"
|
|
|
|
#define TIMEOUT 3
|
|
|
|
#define LOCK_CACHE() pthread_mutex_lock(&cache_lock)
|
|
#define UNLOCK_CACHE() pthread_mutex_unlock(&cache_lock)
|
|
|
|
static pthread_mutex_t cache_lock = PTHREAD_MUTEX_INITIALIZER;
|
|
static su_info *cache;
|
|
|
|
su_info::su_info(unsigned uid) :
|
|
uid(uid), access(DEFAULT_SU_ACCESS), _lock(PTHREAD_MUTEX_INITIALIZER),
|
|
count(0), ref(0), life(0), mgr_st({}) {}
|
|
|
|
su_info::~su_info() {
|
|
pthread_mutex_destroy(&_lock);
|
|
}
|
|
|
|
void su_info::lock() {
|
|
pthread_mutex_lock(&_lock);
|
|
}
|
|
|
|
void su_info::unlock() {
|
|
pthread_mutex_unlock(&_lock);
|
|
}
|
|
|
|
static void *info_collector(void *node) {
|
|
su_info *info = (su_info *) node;
|
|
while (1) {
|
|
sleep(1);
|
|
if (info->life) {
|
|
LOCK_CACHE();
|
|
if (--info->life == 0 && cache && info->uid == cache->uid)
|
|
cache = nullptr;
|
|
UNLOCK_CACHE();
|
|
}
|
|
if (!info->life && !info->ref) {
|
|
delete info;
|
|
return nullptr;
|
|
}
|
|
}
|
|
}
|
|
|
|
static void database_check(su_info *info) {
|
|
int uid = info->uid;
|
|
get_db_settings(&info->cfg);
|
|
get_db_strings(&info->str);
|
|
|
|
// Check multiuser settings
|
|
switch (info->cfg[SU_MULTIUSER_MODE]) {
|
|
case MULTIUSER_MODE_OWNER_ONLY:
|
|
if (info->uid / 100000) {
|
|
uid = -1;
|
|
info->access = NO_SU_ACCESS;
|
|
}
|
|
break;
|
|
case MULTIUSER_MODE_OWNER_MANAGED:
|
|
uid = info->uid % 100000;
|
|
break;
|
|
case MULTIUSER_MODE_USER:
|
|
default:
|
|
break;
|
|
}
|
|
|
|
if (uid > 0)
|
|
get_uid_policy(uid, &info->access);
|
|
|
|
// We need to check our manager
|
|
if (info->access.log || info->access.notify)
|
|
validate_manager(info->str[SU_MANAGER], uid / 100000, &info->mgr_st);
|
|
}
|
|
|
|
static struct su_info *get_su_info(unsigned uid) {
|
|
su_info *info;
|
|
bool cache_miss = false;
|
|
|
|
LOCK_CACHE();
|
|
|
|
if (cache && cache->uid == uid) {
|
|
info = cache;
|
|
} else {
|
|
cache_miss = true;
|
|
info = new su_info(uid);
|
|
cache = info;
|
|
}
|
|
|
|
// Update the cache status
|
|
info->life = TIMEOUT;
|
|
++info->ref;
|
|
|
|
// Start a thread to maintain the cache
|
|
if (cache_miss) {
|
|
pthread_t thread;
|
|
xpthread_create(&thread, nullptr, info_collector, info);
|
|
pthread_detach(thread);
|
|
}
|
|
|
|
UNLOCK_CACHE();
|
|
|
|
LOGD("su: request from uid=[%d] (#%d)\n", info->uid, ++info->count);
|
|
|
|
// Lock before the policy is determined
|
|
info->lock();
|
|
|
|
if (info->access.policy == QUERY) {
|
|
// Not cached, get data from database
|
|
database_check(info);
|
|
|
|
// Check su access settings
|
|
switch (info->cfg[ROOT_ACCESS]) {
|
|
case ROOT_ACCESS_DISABLED:
|
|
LOGW("Root access is disabled!\n");
|
|
info->access = NO_SU_ACCESS;
|
|
break;
|
|
case ROOT_ACCESS_ADB_ONLY:
|
|
if (info->uid != UID_SHELL) {
|
|
LOGW("Root access limited to ADB only!\n");
|
|
info->access = NO_SU_ACCESS;
|
|
}
|
|
break;
|
|
case ROOT_ACCESS_APPS_ONLY:
|
|
if (info->uid == UID_SHELL) {
|
|
LOGW("Root access is disabled for ADB!\n");
|
|
info->access = NO_SU_ACCESS;
|
|
}
|
|
break;
|
|
case ROOT_ACCESS_APPS_AND_ADB:
|
|
default:
|
|
break;
|
|
}
|
|
|
|
// If it's the manager, allow it silently
|
|
if ((info->uid % 100000) == (info->mgr_st.st_uid % 100000))
|
|
info->access = SILENT_SU_ACCESS;
|
|
|
|
// Allow if it's root
|
|
if (info->uid == UID_ROOT)
|
|
info->access = SILENT_SU_ACCESS;
|
|
|
|
// If still not determined, check if manager exists
|
|
if (info->access.policy == QUERY && info->str[SU_MANAGER][0] == '\0')
|
|
info->access = NO_SU_ACCESS;
|
|
}
|
|
|
|
// If still not determined, ask manager
|
|
if (info->access.policy == QUERY) {
|
|
// Create random socket
|
|
struct sockaddr_un addr;
|
|
int sockfd = create_rand_socket(&addr);
|
|
|
|
// Connect manager
|
|
app_connect(addr.sun_path + 1, info);
|
|
int fd = socket_accept(sockfd, 60);
|
|
if (fd < 0) {
|
|
info->access.policy = DENY;
|
|
} else {
|
|
socket_send_request(fd, info);
|
|
int ret = read_int_be(fd);
|
|
info->access.policy = ret < 0 ? DENY : static_cast<policy_t>(ret);
|
|
close(fd);
|
|
}
|
|
close(sockfd);
|
|
}
|
|
|
|
// Unlock
|
|
info->unlock();
|
|
|
|
return info;
|
|
}
|
|
|
|
static void set_identity(unsigned uid) {
|
|
/*
|
|
* Set effective uid back to root, otherwise setres[ug]id will fail
|
|
* if uid isn't root.
|
|
*/
|
|
if (seteuid(0)) {
|
|
PLOGE("seteuid (root)");
|
|
}
|
|
if (setresgid(uid, uid, uid)) {
|
|
PLOGE("setresgid (%u)", uid);
|
|
}
|
|
if (setresuid(uid, uid, uid)) {
|
|
PLOGE("setresuid (%u)", uid);
|
|
}
|
|
}
|
|
|
|
void su_daemon_handler(int client, struct ucred *credential) {
|
|
LOGD("su: request from pid=[%d], client=[%d]\n", credential->pid, client);
|
|
|
|
su_info *info = get_su_info(credential->uid);
|
|
|
|
// Fail fast
|
|
if (info->access.policy == DENY && info->str[SU_MANAGER][0] == '\0') {
|
|
LOGD("su: fast deny\n");
|
|
write_int(client, DENY);
|
|
close(client);
|
|
return;
|
|
}
|
|
|
|
/* Fork a new process, the child process will need to setsid,
|
|
* open a pseudo-terminal if needed, and will eventually run exec
|
|
* The parent process will wait for the result and
|
|
* send the return code back to our client
|
|
*/
|
|
int child = xfork();
|
|
if (child) {
|
|
// Decrement reference count
|
|
--info->ref;
|
|
|
|
// Wait result
|
|
LOGD("su: waiting child pid=[%d]\n", child);
|
|
int status, code;
|
|
|
|
if (waitpid(child, &status, 0) > 0)
|
|
code = WEXITSTATUS(status);
|
|
else
|
|
code = -1;
|
|
|
|
LOGD("su: return code=[%d]\n", code);
|
|
write(client, &code, sizeof(code));
|
|
close(client);
|
|
return;
|
|
}
|
|
|
|
LOGD("su: fork handler\n");
|
|
|
|
// Abort upon any error occurred
|
|
log_cb.ex = exit;
|
|
|
|
struct su_context ctx = {
|
|
.info = info,
|
|
.pid = credential->pid
|
|
};
|
|
|
|
// ack
|
|
write_int(client, 0);
|
|
|
|
// Become session leader
|
|
xsetsid();
|
|
|
|
// Read su_request
|
|
xxread(client, &ctx.req, sizeof(su_req_base));
|
|
ctx.req.shell = read_string(client);
|
|
ctx.req.command = read_string(client);
|
|
|
|
// Get pts_slave
|
|
char *pts_slave = read_string(client);
|
|
|
|
// The FDs for each of the streams
|
|
int infd = recv_fd(client);
|
|
int outfd = recv_fd(client);
|
|
int errfd = recv_fd(client);
|
|
int ptsfd = -1;
|
|
|
|
if (pts_slave[0]) {
|
|
LOGD("su: pts_slave=[%s]\n", pts_slave);
|
|
// Check pts_slave file is owned by daemon_from_uid
|
|
struct stat st;
|
|
xstat(pts_slave, &st);
|
|
|
|
// If caller is not root, ensure the owner of pts_slave is the caller
|
|
if(st.st_uid != info->uid && info->uid != 0)
|
|
LOGE("su: Wrong permission of pts_slave");
|
|
|
|
// Set our pts_slave to devpts, same restriction as adb shell
|
|
lsetfilecon(pts_slave, "u:object_r:devpts:s0");
|
|
|
|
// Opening the TTY has to occur after the
|
|
// fork() and setsid() so that it becomes
|
|
// our controlling TTY and not the daemon's
|
|
ptsfd = xopen(pts_slave, O_RDWR);
|
|
|
|
if (infd < 0)
|
|
infd = ptsfd;
|
|
if (outfd < 0)
|
|
outfd = ptsfd;
|
|
if (errfd < 0)
|
|
errfd = ptsfd;
|
|
}
|
|
|
|
free(pts_slave);
|
|
|
|
// Swap out stdin, stdout, stderr
|
|
xdup2(infd, STDIN_FILENO);
|
|
xdup2(outfd, STDOUT_FILENO);
|
|
xdup2(errfd, STDERR_FILENO);
|
|
|
|
close(ptsfd);
|
|
close(client);
|
|
|
|
// Handle namespaces
|
|
if (ctx.req.mount_master)
|
|
info->cfg[SU_MNT_NS] = NAMESPACE_MODE_GLOBAL;
|
|
switch (info->cfg[SU_MNT_NS]) {
|
|
case NAMESPACE_MODE_GLOBAL:
|
|
LOGD("su: use global namespace\n");
|
|
break;
|
|
case NAMESPACE_MODE_REQUESTER:
|
|
LOGD("su: use namespace of pid=[%d]\n", ctx.pid);
|
|
if (switch_mnt_ns(ctx.pid)) {
|
|
LOGD("su: setns failed, fallback to isolated\n");
|
|
xunshare(CLONE_NEWNS);
|
|
}
|
|
break;
|
|
case NAMESPACE_MODE_ISOLATE:
|
|
LOGD("su: use new isolated namespace\n");
|
|
xunshare(CLONE_NEWNS);
|
|
break;
|
|
}
|
|
|
|
if (info->access.log)
|
|
app_log(&ctx);
|
|
else if (info->access.notify)
|
|
app_notify(&ctx);
|
|
|
|
if (info->access.policy == ALLOW) {
|
|
const char *argv[] = { nullptr, nullptr, nullptr, nullptr };
|
|
|
|
argv[0] = ctx.req.login ? "-" : ctx.req.shell;
|
|
|
|
if (ctx.req.command[0]) {
|
|
argv[1] = "-c";
|
|
argv[2] = ctx.req.command;
|
|
}
|
|
|
|
// Setup environment
|
|
umask(022);
|
|
set_identity(ctx.req.uid);
|
|
char path[32], buf[4096];
|
|
snprintf(path, sizeof(path), "/proc/%d/cwd", ctx.pid);
|
|
xreadlink(path, buf, sizeof(buf));
|
|
chdir(buf);
|
|
snprintf(path, sizeof(path), "/proc/%d/environ", ctx.pid);
|
|
memset(buf, 0, sizeof(buf));
|
|
int fd = open(path, O_RDONLY);
|
|
read(fd, buf, sizeof(buf));
|
|
close(fd);
|
|
clearenv();
|
|
for (size_t pos = 0; buf[pos];) {
|
|
putenv(buf + pos);
|
|
pos += strlen(buf + pos) + 1;
|
|
}
|
|
if (!ctx.req.keepenv) {
|
|
struct passwd *pw;
|
|
pw = getpwuid(ctx.req.uid);
|
|
if (pw) {
|
|
setenv("HOME", pw->pw_dir, 1);
|
|
if (ctx.req.login || ctx.req.uid) {
|
|
setenv("USER", pw->pw_name, 1);
|
|
setenv("LOGNAME", pw->pw_name, 1);
|
|
}
|
|
setenv("SHELL", ctx.req.shell, 1);
|
|
}
|
|
}
|
|
|
|
execvp(ctx.req.shell, (char **) argv);
|
|
fprintf(stderr, "Cannot execute %s: %s\n", ctx.req.shell, strerror(errno));
|
|
PLOGE("exec");
|
|
exit(EXIT_FAILURE);
|
|
} else {
|
|
LOGW("su: request rejected (%u->%u)", info->uid, ctx.req.uid);
|
|
fprintf(stderr, "%s\n", strerror(EACCES));
|
|
exit(EXIT_FAILURE);
|
|
}
|
|
}
|