270 lines
5.6 KiB
C
270 lines
5.6 KiB
C
/* su_client.c - The entrypoint for su, connect to daemon and send correct info
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*/
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#include <limits.h>
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#include <unistd.h>
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#include <pthread.h>
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#include <stdlib.h>
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#include <fcntl.h>
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#include <string.h>
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#include <signal.h>
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#include <sys/socket.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <sys/wait.h>
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#include "magisk.h"
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#include "daemon.h"
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#include "utils.h"
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#include "su.h"
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#include "pts.h"
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// Constants for the atty bitfield
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#define ATTY_IN 1
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#define ATTY_OUT 2
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#define ATTY_ERR 4
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int from_uid, from_pid;
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static void sighandler(int sig) {
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restore_stdin();
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// Assume we'll only be called before death
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// See note before sigaction() in set_stdin_raw()
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//
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// Now, close all standard I/O to cause the pumps
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// to exit so we can continue and retrieve the exit
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// code
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close(STDIN_FILENO);
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close(STDOUT_FILENO);
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close(STDERR_FILENO);
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// Put back all the default handlers
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struct sigaction act;
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memset(&act, 0, sizeof(act));
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act.sa_handler = SIG_DFL;
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for (int i = 0; quit_signals[i]; ++i) {
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sigaction(quit_signals[i], &act, NULL);
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}
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}
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void su_daemon_receiver(int client) {
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LOGD("su: get request\n");
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if (fork_zero_fucks()) {
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// Root daemon
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close(client);
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return;
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}
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// Set the error handler back to normal
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err_handler = exit_proc;
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// Fork a new process, the child process will need to setsid,
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// open a pseudo-terminal, and will eventually run exec
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// The parent process will wait for the result and
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// send the return code back to our client
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int child = fork();
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if (child < 0) {
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write(client, &child, sizeof(child));
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close(client);
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PLOGE("fork");
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return;
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} else if (child != 0) {
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// Wait result
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LOGD("su: wait_result waiting for %d\n", child);
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int status, code;
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// Change to a fancy name
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strcpy(argv0, "magisksu");
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if (waitpid(child, &status, 0) > 0)
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code = WEXITSTATUS(status);
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else
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code = -1;
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// Pass the return code back to the client
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write_int(client, code);
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LOGD("su: return code to client: %d\n", code);
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close(client);
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exit(code);
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}
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LOGD("su: child process started\n");
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// ack
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write_int(client, 1);
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// Become session leader
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xsetsid();
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// Check the credentials
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struct ucred credentials;
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get_client_cred(client, &credentials);
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from_uid = credentials.uid;
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from_pid = credentials.pid;
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// Let's read some info from the socket
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int argc = read_int(client);
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if (argc < 0 || argc > 512) {
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LOGE("unable to allocate args: %d", argc);
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exit(1);
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}
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LOGD("su: argc=[%d]\n", argc);
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char **argv = (char**) xmalloc(sizeof(char*) * (argc + 1));
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argv[argc] = NULL;
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for (int i = 0; i < argc; i++) {
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argv[i] = read_string(client);
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LOGD("su: argv[%d]=[%s]\n", i, argv[i]);
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}
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// Change directory to cwd
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char *cwd = read_string(client);
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LOGD("su: cwd=[%s]\n", cwd);
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chdir(cwd);
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free(cwd);
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// Get pts_slave
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char *pts_slave = read_string(client);
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LOGD("su: pts_slave=[%s]\n", pts_slave);
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// The the FDs for each of the streams
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int infd = recv_fd(client);
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int outfd = recv_fd(client);
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int errfd = recv_fd(client);
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// We no longer need the access to socket in the child, close it
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close(client);
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if (pts_slave[0]) {
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//Check pts_slave file is owned by daemon_from_uid
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struct stat stbuf;
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xstat(pts_slave, &stbuf);
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//If caller is not root, ensure the owner of pts_slave is the caller
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if(stbuf.st_uid != credentials.uid && credentials.uid != 0) {
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LOGE("su: Wrong permission of pts_slave");
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exit(1);
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}
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// Opening the TTY has to occur after the
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// fork() and setsid() so that it becomes
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// our controlling TTY and not the daemon's
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int ptsfd = xopen(pts_slave, O_RDWR);
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if (infd < 0) {
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LOGD("su: stdin using PTY");
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infd = ptsfd;
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}
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if (outfd < 0) {
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LOGD("su: stdout using PTY");
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outfd = ptsfd;
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}
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if (errfd < 0) {
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LOGD("su: stderr using PTY");
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errfd = ptsfd;
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}
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}
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free(pts_slave);
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// Swap out stdin, stdout, stderr
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xdup2(infd, STDIN_FILENO);
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xdup2(outfd, STDOUT_FILENO);
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xdup2(errfd, STDERR_FILENO);
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su_daemon_main(argc, argv);
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}
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/*
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* Connect daemon, send argc, argv, cwd, pts slave
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*/
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int su_client_main(int argc, char *argv[]) {
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char buffer[PATH_MAX];
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int ptmx, socketfd;
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// Connect to client
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socketfd = connect_daemon();
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// Tell the daemon we are su
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write_int(socketfd, SUPERUSER);
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// Number of command line arguments
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write_int(socketfd, argc);
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// Command line arguments
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for (int i = 0; i < argc; i++) {
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write_string(socketfd, argv[i]);
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}
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// CWD
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getcwd(buffer, sizeof(buffer));
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write_string(socketfd, buffer);
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// Determine which one of our streams are attached to a TTY
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int atty = 0;
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if (isatty(STDIN_FILENO)) atty |= ATTY_IN;
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if (isatty(STDOUT_FILENO)) atty |= ATTY_OUT;
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if (isatty(STDERR_FILENO)) atty |= ATTY_ERR;
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if (atty) {
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// We need a PTY. Get one.
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ptmx = pts_open(buffer, sizeof(buffer));
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} else {
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buffer[0] = '\0';
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}
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// Send the pts_slave path to the daemon
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write_string(socketfd, buffer);
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// Send stdin
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if (atty & ATTY_IN) {
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// Using PTY
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send_fd(socketfd, -1);
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} else {
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send_fd(socketfd, STDIN_FILENO);
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}
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// Send stdout
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if (atty & ATTY_OUT) {
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// Forward SIGWINCH
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watch_sigwinch_async(STDOUT_FILENO, ptmx);
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// Using PTY
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send_fd(socketfd, -1);
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} else {
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send_fd(socketfd, STDOUT_FILENO);
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}
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// Send stderr
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if (atty & ATTY_ERR) {
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// Using PTY
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send_fd(socketfd, -1);
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} else {
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send_fd(socketfd, STDERR_FILENO);
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}
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// Wait for acknowledgement from daemon
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read_int(socketfd);
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if (atty & ATTY_IN) {
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setup_sighandlers(sighandler);
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pump_stdin_async(ptmx);
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}
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if (atty & ATTY_OUT) {
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pump_stdout_blocking(ptmx);
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}
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// Get the exit code
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int code = read_int(socketfd);
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close(socketfd);
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return code;
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}
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