Magisk/native/jni/su/su.cpp

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/*
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* Copyright 2017 - 2021, John Wu (@topjohnwu)
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* Copyright 2015, Pierre-Hugues Husson <phh@phh.me>
* Copyright 2010, Adam Shanks (@ChainsDD)
* Copyright 2008, Zinx Verituse (@zinxv)
*/
#include <unistd.h>
#include <getopt.h>
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#include <fcntl.h>
#include <pwd.h>
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#include <sched.h>
#include <sys/types.h>
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#include <sys/stat.h>
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#include <magisk.hpp>
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#include <daemon.hpp>
#include <utils.hpp>
#include <flags.hpp>
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#include "su.hpp"
#include "pts.hpp"
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int quit_signals[] = { SIGALRM, SIGABRT, SIGHUP, SIGPIPE, SIGQUIT, SIGTERM, SIGINT, 0 };
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static void usage(int status) {
FILE *stream = (status == EXIT_SUCCESS) ? stdout : stderr;
fprintf(stream,
"MagiskSU\n\n"
"Usage: su [options] [-] [user [argument...]]\n\n"
"Options:\n"
" -c, --command COMMAND pass COMMAND to the invoked shell\n"
" -h, --help display this help message and exit\n"
" -, -l, --login pretend the shell to be a login shell\n"
" -m, -p,\n"
" --preserve-environment preserve the entire environment\n"
" -s, --shell SHELL use SHELL instead of the default " DEFAULT_SHELL "\n"
" -v, --version display version number and exit\n"
" -V display version code and exit\n"
" -mm, -M,\n"
" --mount-master force run in the global mount namespace\n");
exit(status);
}
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static void sighandler(int sig) {
restore_stdin();
// Assume we'll only be called before death
// See note before sigaction() in set_stdin_raw()
//
// Now, close all standard I/O to cause the pumps
// to exit so we can continue and retrieve the exit
// code
close(STDIN_FILENO);
close(STDOUT_FILENO);
close(STDERR_FILENO);
// Put back all the default handlers
struct sigaction act;
memset(&act, 0, sizeof(act));
act.sa_handler = SIG_DFL;
for (int i = 0; quit_signals[i]; ++i) {
sigaction(quit_signals[i], &act, nullptr);
}
}
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static void setup_sighandlers(void (*handler)(int)) {
struct sigaction act;
memset(&act, 0, sizeof(act));
act.sa_handler = handler;
for (int i = 0; quit_signals[i]; ++i) {
sigaction(quit_signals[i], &act, nullptr);
}
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}
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int su_client_main(int argc, char *argv[]) {
int c;
struct option long_opts[] = {
{ "command", required_argument, nullptr, 'c' },
{ "help", no_argument, nullptr, 'h' },
{ "login", no_argument, nullptr, 'l' },
{ "preserve-environment", no_argument, nullptr, 'p' },
{ "shell", required_argument, nullptr, 's' },
{ "version", no_argument, nullptr, 'v' },
{ "context", required_argument, nullptr, 'z' },
{ "mount-master", no_argument, nullptr, 'M' },
{ nullptr, 0, nullptr, 0 },
};
su_request su_req;
for (int i = 0; i < argc; i++) {
// Replace -cn with -z, -mm with -M for supporting getopt_long
if (strcmp(argv[i], "-cn") == 0)
strcpy(argv[i], "-z");
else if (strcmp(argv[i], "-mm") == 0)
strcpy(argv[i], "-M");
}
while ((c = getopt_long(argc, argv, "c:hlmps:Vvuz:M", long_opts, nullptr)) != -1) {
switch (c) {
case 'c':
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for (int i = optind - 1; i < argc; ++i) {
if (!su_req.command.empty())
su_req.command += ' ';
su_req.command += argv[i];
}
optind = argc;
break;
case 'h':
usage(EXIT_SUCCESS);
break;
case 'l':
su_req.login = true;
break;
case 'm':
case 'p':
su_req.keepenv = true;
break;
case 's':
su_req.shell = optarg;
break;
case 'V':
printf("%d\n", MAGISK_VER_CODE);
exit(EXIT_SUCCESS);
case 'v':
printf("%s\n", MAGISK_VERSION ":MAGISKSU");
exit(EXIT_SUCCESS);
case 'z':
// Do nothing, placed here for legacy support :)
break;
case 'M':
su_req.mount_master = true;
break;
default:
/* Bionic getopt_long doesn't terminate its error output by newline */
fprintf(stderr, "\n");
usage(2);
}
}
if (optind < argc && strcmp(argv[optind], "-") == 0) {
su_req.login = true;
optind++;
}
/* username or uid */
if (optind < argc) {
struct passwd *pw;
pw = getpwnam(argv[optind]);
if (pw)
su_req.uid = pw->pw_uid;
else
su_req.uid = parse_int(argv[optind]);
optind++;
}
char pts_slave[PATH_MAX];
int ptmx, fd;
// Connect to client
fd = connect_daemon();
// Tell the daemon we are su
write_int(fd, SUPERUSER);
// Send su_request
xwrite(fd, &su_req, sizeof(su_req_base));
write_string(fd, su_req.shell);
write_string(fd, su_req.command);
// Wait for ack from daemon
if (read_int(fd)) {
// Fast fail
fprintf(stderr, "%s\n", strerror(EACCES));
return EACCES;
}
// Determine which one of our streams are attached to a TTY
int atty = 0;
if (isatty(STDIN_FILENO)) atty |= ATTY_IN;
if (isatty(STDOUT_FILENO)) atty |= ATTY_OUT;
if (isatty(STDERR_FILENO)) atty |= ATTY_ERR;
if (atty) {
// We need a PTY. Get one.
ptmx = pts_open(pts_slave, sizeof(pts_slave));
} else {
pts_slave[0] = '\0';
}
// Send pts_slave
write_string(fd, pts_slave);
// Send stdin
send_fd(fd, (atty & ATTY_IN) ? -1 : STDIN_FILENO);
// Send stdout
send_fd(fd, (atty & ATTY_OUT) ? -1 : STDOUT_FILENO);
// Send stderr
send_fd(fd, (atty & ATTY_ERR) ? -1 : STDERR_FILENO);
if (atty) {
setup_sighandlers(sighandler);
watch_sigwinch_async(STDOUT_FILENO, ptmx);
pump_stdin_async(ptmx);
pump_stdout_blocking(ptmx);
}
// Get the exit code
int code = read_int(fd);
close(fd);
return code;
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}