src/shared/spawn-polkit-agent.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2 /***
   3   This file is part of systemd.
   4
   5   Copyright 2011 Lennart Poettering
   6 ***/
   7
   8 #include <errno.h>
   9 #include <poll.h>
  10 #include <signal.h>
  11 #include <stdlib.h>
  12 #include <unistd.h>
  13
  14 #include "fd-util.h"
  15 #include "io-util.h"
  16 #include "log.h"
  17 #include "macro.h"
  18 #include "process-util.h"
  19 #include "spawn-polkit-agent.h"
  20 #include "stdio-util.h"
  21 #include "time-util.h"
  22 #include "util.h"
  23
  24 #if ENABLE_POLKIT
  25 static pid_t agent_pid = 0;
  26
  27 int polkit_agent_open(void) {
  28         char notify_fd[DECIMAL_STR_MAX(int) + 1];
  29         int pipe_fd[2], r;
  30
  31         if (agent_pid > 0)
  32                 return 0;
  33
  34         /* Clients that run as root don't need to activate/query polkit */
  35         if (geteuid() == 0)
  36                 return 0;
  37
  38         /* We check STDIN here, not STDOUT, since this is about input, not output */
  39         if (!isatty(STDIN_FILENO))
  40                 return 0;
  41
  42         if (!is_main_thread())
  43                 return -EPERM;
  44
  45         if (pipe2(pipe_fd, 0) < 0)
  46                 return -errno;
  47
  48         xsprintf(notify_fd, "%i", pipe_fd[1]);
  49
  50         r = fork_agent("(polkit-agent)",
  51                        &pipe_fd[1], 1,
  52                        &agent_pid,
  53                        POLKIT_AGENT_BINARY_PATH,
  54                        POLKIT_AGENT_BINARY_PATH, "--notify-fd", notify_fd, "--fallback", NULL);
  55
  56         /* Close the writing side, because that's the one for the agent */
  57         safe_close(pipe_fd[1]);
  58
  59         if (r < 0)
  60                 log_error_errno(r, "Failed to fork TTY ask password agent: %m");
  61         else
  62                 /* Wait until the agent closes the fd */
  63                 fd_wait_for_event(pipe_fd[0], POLLHUP, USEC_INFINITY);
  64
  65         safe_close(pipe_fd[0]);
  66
  67         return r;
  68 }
  69
  70 void polkit_agent_close(void) {
  71
  72         if (agent_pid <= 0)
  73                 return;
  74
  75         /* Inform agent that we are done */
  76         (void) kill_and_sigcont(agent_pid, SIGTERM);
  77         (void) wait_for_terminate(agent_pid, NULL);
  78         agent_pid = 0;
  79 }
  80
  81 #else
  82
  83 int polkit_agent_open(void) {
  84         return 0;
  85 }
  86
  87 void polkit_agent_close(void) {
  88 }
  89
  90 #endif