Line data Source code
1 : /* SPDX-License-Identifier: LGPL-2.1+ */
2 :
3 : #include <sys/reboot.h>
4 : #include <sys/wait.h>
5 : #include <sys/prctl.h>
6 : #include <unistd.h>
7 :
8 : #include "def.h"
9 : #include "exit-status.h"
10 : #include "fd-util.h"
11 : #include "log.h"
12 : #include "missing.h"
13 : #include "nspawn-stub-pid1.h"
14 : #include "process-util.h"
15 : #include "signal-util.h"
16 : #include "time-util.h"
17 :
18 0 : static int reset_environ(const char *new_environment, size_t length) {
19 : unsigned long start, end;
20 :
21 0 : start = (unsigned long) new_environment;
22 0 : end = start + length;
23 :
24 0 : if (prctl(PR_SET_MM, PR_SET_MM_ENV_START, start, 0, 0) < 0)
25 0 : return -errno;
26 :
27 0 : if (prctl(PR_SET_MM, PR_SET_MM_ENV_END, end, 0, 0) < 0)
28 0 : return -errno;
29 :
30 0 : return 0;
31 : }
32 :
33 0 : int stub_pid1(sd_id128_t uuid) {
34 : enum {
35 : STATE_RUNNING,
36 : STATE_REBOOT,
37 : STATE_POWEROFF,
38 0 : } state = STATE_RUNNING;
39 :
40 : sigset_t fullmask, oldmask, waitmask;
41 0 : usec_t quit_usec = USEC_INFINITY;
42 : pid_t pid;
43 : int r;
44 :
45 : /* The new environment we set up, on the stack. */
46 0 : char new_environment[] =
47 : "container=systemd-nspawn\0"
48 : "container_uuid=XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX";
49 :
50 : /* Implements a stub PID 1, that reaps all processes and processes a couple of standard signals. This is useful
51 : * for allowing arbitrary processes run in a container, and still have all zombies reaped. */
52 :
53 0 : assert_se(sigfillset(&fullmask) >= 0);
54 0 : assert_se(sigprocmask(SIG_BLOCK, &fullmask, &oldmask) >= 0);
55 :
56 0 : pid = fork();
57 0 : if (pid < 0)
58 0 : return log_error_errno(errno, "Failed to fork child pid: %m");
59 :
60 0 : if (pid == 0) {
61 : /* Return in the child */
62 0 : assert_se(sigprocmask(SIG_SETMASK, &oldmask, NULL) >= 0);
63 0 : setsid();
64 0 : return 0;
65 : }
66 :
67 0 : reset_all_signal_handlers();
68 :
69 0 : log_close();
70 0 : (void) close_all_fds(NULL, 0);
71 0 : log_open();
72 :
73 : /* Flush out /proc/self/environ, so that we don't leak the environment from the host into the container. Also,
74 : * set $container= and $container_uuid= so that clients in the container that query it from /proc/1/environ
75 : * find them set. */
76 0 : sd_id128_to_string(uuid, new_environment + sizeof(new_environment) - SD_ID128_STRING_MAX);
77 0 : reset_environ(new_environment, sizeof(new_environment));
78 :
79 0 : (void) rename_process("(sd-stubinit)");
80 :
81 0 : assert_se(sigemptyset(&waitmask) >= 0);
82 0 : assert_se(sigset_add_many(&waitmask,
83 : SIGCHLD, /* posix: process died */
84 : SIGINT, /* sysv: ctrl-alt-del */
85 : SIGRTMIN+3, /* systemd: halt */
86 : SIGRTMIN+4, /* systemd: poweroff */
87 : SIGRTMIN+5, /* systemd: reboot */
88 : SIGRTMIN+6, /* systemd: kexec */
89 : SIGRTMIN+13, /* systemd: halt */
90 : SIGRTMIN+14, /* systemd: poweroff */
91 : SIGRTMIN+15, /* systemd: reboot */
92 : SIGRTMIN+16, /* systemd: kexec */
93 : -1) >= 0);
94 :
95 : /* Note that we ignore SIGTERM (sysv's reexec), SIGHUP (reload), and all other signals here, since we don't
96 : * support reexec/reloading in this stub process. */
97 :
98 0 : for (;;) {
99 : siginfo_t si;
100 : usec_t current_usec;
101 :
102 0 : si.si_pid = 0;
103 0 : r = waitid(P_ALL, 0, &si, WEXITED|WNOHANG);
104 0 : if (r < 0) {
105 0 : r = log_error_errno(errno, "Failed to reap children: %m");
106 0 : goto finish;
107 : }
108 :
109 0 : current_usec = now(CLOCK_MONOTONIC);
110 :
111 0 : if (si.si_pid == pid || current_usec >= quit_usec) {
112 :
113 : /* The child we started ourselves died or we reached a timeout. */
114 :
115 0 : if (state == STATE_REBOOT) { /* dispatch a queued reboot */
116 0 : (void) reboot(RB_AUTOBOOT);
117 0 : r = log_error_errno(errno, "Failed to reboot: %m");
118 0 : goto finish;
119 :
120 0 : } else if (state == STATE_POWEROFF)
121 0 : (void) reboot(RB_POWER_OFF); /* if this fails, fall back to normal exit. */
122 :
123 0 : if (si.si_pid == pid && si.si_code == CLD_EXITED)
124 0 : r = si.si_status; /* pass on exit code */
125 : else
126 0 : r = EXIT_EXCEPTION; /* signal, coredump, timeout, … */
127 :
128 0 : goto finish;
129 : }
130 0 : if (si.si_pid != 0)
131 : /* We reaped something. Retry until there's nothing more to reap. */
132 0 : continue;
133 :
134 0 : if (quit_usec == USEC_INFINITY)
135 0 : r = sigwaitinfo(&waitmask, &si);
136 : else {
137 : struct timespec ts;
138 0 : r = sigtimedwait(&waitmask, &si, timespec_store(&ts, quit_usec - current_usec));
139 : }
140 0 : if (r < 0) {
141 0 : if (errno == EINTR) /* strace -p attach can result in EINTR, let's handle this nicely. */
142 0 : continue;
143 0 : if (errno == EAGAIN) /* timeout reached */
144 0 : continue;
145 :
146 0 : r = log_error_errno(errno, "Failed to wait for signal: %m");
147 0 : goto finish;
148 : }
149 :
150 0 : if (si.si_signo == SIGCHLD)
151 0 : continue; /* Let's reap this */
152 :
153 0 : if (state != STATE_RUNNING)
154 0 : continue;
155 :
156 : /* Would love to use a switch() statement here, but SIGRTMIN is actually a function call, not a
157 : * constant… */
158 :
159 0 : if (si.si_signo == SIGRTMIN+3 ||
160 0 : si.si_signo == SIGRTMIN+4 ||
161 0 : si.si_signo == SIGRTMIN+13 ||
162 0 : si.si_signo == SIGRTMIN+14)
163 :
164 0 : state = STATE_POWEROFF;
165 :
166 0 : else if (si.si_signo == SIGINT ||
167 0 : si.si_signo == SIGRTMIN+5 ||
168 0 : si.si_signo == SIGRTMIN+6 ||
169 0 : si.si_signo == SIGRTMIN+15 ||
170 0 : si.si_signo == SIGRTMIN+16)
171 :
172 0 : state = STATE_REBOOT;
173 : else
174 0 : assert_not_reached("Got unexpected signal");
175 :
176 0 : r = kill_and_sigcont(pid, SIGTERM);
177 :
178 : /* Let's send a SIGHUP after the SIGTERM, as shells tend to ignore SIGTERM but do react to SIGHUP. We
179 : * do it strictly in this order, so that the SIGTERM is dispatched first, and SIGHUP second for those
180 : * processes which handle both. That's because services tend to bind configuration reload or something
181 : * else to SIGHUP. */
182 :
183 0 : if (r != -ESRCH)
184 0 : (void) kill(pid, SIGHUP);
185 :
186 0 : quit_usec = now(CLOCK_MONOTONIC) + DEFAULT_TIMEOUT_USEC;
187 : }
188 :
189 0 : finish:
190 0 : _exit(r < 0 ? EXIT_FAILURE : r);
191 : }
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