src/shared/spawn-polkit-agent.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2
   3 #include <errno.h>
   4 #include <poll.h>
   5 #include <signal.h>
   6 #include <stdlib.h>
   7 #include <unistd.h>
   8
   9 #include "fd-util.h"
  10 #include "io-util.h"
  11 #include "log.h"
  12 #include "macro.h"
  13 #include "process-util.h"
  14 #include "spawn-polkit-agent.h"
  15 #include "stdio-util.h"
  16 #include "time-util.h"
  17 #include "util.h"
  18
  19 #if ENABLE_POLKIT
  20 static pid_t agent_pid = 0;
  21
  22 int polkit_agent_open(void) {
  23         char notify_fd[DECIMAL_STR_MAX(int) + 1];
  24         int pipe_fd[2], r;
  25
  26         if (agent_pid > 0)
  27                 return 0;
  28
  29         /* Clients that run as root don't need to activate/query polkit */
  30         if (geteuid() == 0)
  31                 return 0;
  32
  33         /* We check STDIN here, not STDOUT, since this is about input, not output */
  34         if (!isatty(STDIN_FILENO))
  35                 return 0;
  36
  37         if (!is_main_thread())
  38                 return -EPERM;
  39
  40         if (pipe2(pipe_fd, 0) < 0)
  41                 return -errno;
  42
  43         xsprintf(notify_fd, "%i", pipe_fd[1]);
  44
  45         r = fork_agent("(polkit-agent)",
  46                        &pipe_fd[1], 1,
  47                        &agent_pid,
  48                        POLKIT_AGENT_BINARY_PATH,
  49                        POLKIT_AGENT_BINARY_PATH, "--notify-fd", notify_fd, "--fallback", NULL);
  50
  51         /* Close the writing side, because that's the one for the agent */
  52         safe_close(pipe_fd[1]);
  53
  54         if (r < 0)
  55                 log_error_errno(r, "Failed to fork TTY ask password agent: %m");
  56         else
  57                 /* Wait until the agent closes the fd */
  58                 fd_wait_for_event(pipe_fd[0], POLLHUP, USEC_INFINITY);
  59
  60         safe_close(pipe_fd[0]);
  61
  62         return r;
  63 }
  64
  65 void polkit_agent_close(void) {
  66
  67         if (agent_pid <= 0)
  68                 return;
  69
  70         /* Inform agent that we are done */
  71         (void) kill_and_sigcont(agent_pid, SIGTERM);
  72         (void) wait_for_terminate(agent_pid, NULL);
  73         agent_pid = 0;
  74 }
  75
  76 #else
  77
  78 int polkit_agent_open(void) {
  79         return 0;
  80 }
  81
  82 void polkit_agent_close(void) {
  83 }
  84
  85 #endif
  86
  87 int polkit_agent_open_if_enabled(BusTransport transport, bool ask_password) {
  88
  89         /* Open the polkit agent as a child process if necessary */
  90
  91         if (transport != BUS_TRANSPORT_LOCAL)
  92                 return 0;
  93
  94         if (!ask_password)
  95                 return 0;
  96
  97         return polkit_agent_open();
  98 }