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systemd/src/socket-activate/socket-activate.c
Daan De Meyer 792a8bfb8a daemon-util: Rename starting/stopping message constants 
Currently, NOTIFY_READY from daemon-util.h conflicts with NOTIFY_READY
from NotifyState from service.h so let's rename the constants to avoid
the conflict.
2025-05-01 14:02:17 +02:00

506 lines
17 KiB
C
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/* SPDX-License-Identifier: LGPL-2.1-or-later */
#include <getopt.h>
#include <sys/epoll.h>
#include <sys/prctl.h>
#include <sys/wait.h>
#include <unistd.h>
#include "sd-daemon.h"
#include "alloc-util.h"
#include "build.h"
#include "daemon-util.h"
#include "env-util.h"
#include "errno-util.h"
#include "escape.h"
#include "fd-util.h"
#include "log.h"
#include "macro.h"
#include "main-func.h"
#include "pretty-print.h"
#include "process-util.h"
#include "signal-util.h"
#include "socket-netlink.h"
#include "socket-util.h"
#include "string-util.h"
#include "strv.h"
#include "terminal-util.h"
static char **arg_listen = NULL;
static bool arg_accept = false;
static int arg_socket_type = SOCK_STREAM;
static char **arg_setenv = NULL;
static char **arg_fdnames = NULL;
static bool arg_inetd = false;
static int add_epoll(int epoll_fd, int fd) {
struct epoll_event ev = {
.events = EPOLLIN,
.data.fd = fd,
};
assert(epoll_fd >= 0);
assert(fd >= 0);
if (epoll_ctl(epoll_fd, EPOLL_CTL_ADD, fd, &ev) < 0)
return log_error_errno(errno, "Failed to add event on epoll fd:%d for fd:%d: %m", epoll_fd, fd);
return 0;
}
static int open_sockets(int *ret_epoll_fd) {
_cleanup_close_ int epoll_fd = -EBADF;
int n, r, count = 0;
assert(ret_epoll_fd);
n = sd_listen_fds(true);
if (n < 0)
return log_error_errno(n, "Failed to read listening file descriptors from environment: %m");
if (n > 0) {
log_info("Received %i descriptors via the environment.", n);
for (int fd = SD_LISTEN_FDS_START; fd < SD_LISTEN_FDS_START + n; fd++) {
r = fd_cloexec(fd, arg_accept);
if (r < 0)
return r;
count++;
}
}
/* Close logging and all other descriptors */
if (arg_listen) {
_cleanup_free_ int *except = new(int, n);
if (!except)
return log_oom();
for (int i = 0; i < n; i++)
except[i] = SD_LISTEN_FDS_START + i;
log_close();
log_set_open_when_needed(true);
log_settle_target();
r = close_all_fds(except, n);
if (r < 0)
return log_error_errno(r, "Failed to close all file descriptors: %m");
}
/* Note: we leak some fd's on error here. It doesn't matter much, since the program will exit
* immediately anyway, but would be a pain to fix. */
STRV_FOREACH(address, arg_listen) {
r = make_socket_fd(LOG_DEBUG, *address, arg_socket_type, (arg_accept * SOCK_CLOEXEC));
if (r < 0)
return log_error_errno(r, "Failed to open '%s': %m", *address);
assert(r == SD_LISTEN_FDS_START + count);
count++;
}
if (arg_listen) {
log_open();
log_set_open_when_needed(false);
}
epoll_fd = epoll_create1(EPOLL_CLOEXEC);
if (epoll_fd < 0)
return log_error_errno(errno, "Failed to create epoll object: %m");
for (int fd = SD_LISTEN_FDS_START; fd < SD_LISTEN_FDS_START + count; fd++) {
_cleanup_free_ char *name = NULL;
getsockname_pretty(fd, &name);
log_info("Listening on %s as %i.", strna(name), fd);
r = add_epoll(epoll_fd, fd);
if (r < 0)
return r;
}
*ret_epoll_fd = TAKE_FD(epoll_fd);
return count;
}
static int exec_process(char * const *argv, int start_fd, size_t n_fds) {
_cleanup_strv_free_ char **envp = NULL;
int r;
assert(!strv_isempty(argv));
assert(start_fd >= 0);
assert(n_fds > 0);
if (arg_inetd && n_fds != 1)
return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
"--inetd only supported for single file descriptors.");
FOREACH_STRING(var, "TERM", "COLORTERM", "NO_COLOR", "PATH", "USER", "HOME") {
const char *n;
n = strv_find_prefix(environ, var);
if (!n)
continue;
r = strv_extend(&envp, n);
if (r < 0)
return r;
}
if (arg_inetd) {
assert(n_fds == 1);
r = rearrange_stdio(start_fd, start_fd, STDERR_FILENO); /* invalidates start_fd on success + error */
if (r < 0)
return log_error_errno(r, "Failed to move fd to stdin+stdout: %m");
} else {
if (start_fd != SD_LISTEN_FDS_START) {
assert(n_fds == 1);
if (dup2(start_fd, SD_LISTEN_FDS_START) < 0)
return log_error_errno(errno, "Failed to dup connection: %m");
safe_close(start_fd);
}
r = strv_extendf(&envp, "LISTEN_FDS=%zu", n_fds);
if (r < 0)
return r;
r = strv_extendf(&envp, "LISTEN_PID=" PID_FMT, getpid_cached());
if (r < 0)
return r;
if (arg_fdnames) {
_cleanup_free_ char *names = NULL;
size_t len;
len = strv_length(arg_fdnames);
if (len == 1)
for (size_t i = 1; i < n_fds; i++) {
r = strv_extend(&arg_fdnames, arg_fdnames[0]);
if (r < 0)
return log_oom();
}
else if (len != n_fds)
log_warning("The number of fd names is different than number of fds: %zu vs %zu", len, n_fds);
names = strv_join(arg_fdnames, ":");
if (!names)
return log_oom();
char *t = strjoin("LISTEN_FDNAMES=", names);
if (!t)
return log_oom();
r = strv_consume(&envp, t);
if (r < 0)
return r;
}
}
STRV_FOREACH(s, arg_setenv) {
r = strv_env_replace_strdup(&envp, *s);
if (r < 0)
return r;
}
_cleanup_free_ char *joined = strv_join(argv, " ");
if (!joined)
return log_oom();
log_info("Executing: %s", joined);
execvpe(argv[0], argv, envp);
return log_error_errno(errno, "Failed to execute '%s': %m", joined);
}
static int fork_and_exec_process(char * const *argv, int fd) {
_cleanup_free_ char *joined = NULL;
pid_t child_pid;
int r;
assert(!strv_isempty(argv));
assert(fd >= 0);
joined = strv_join(argv, " ");
if (!joined)
return log_oom();
r = safe_fork("(activate)",
FORK_RESET_SIGNALS | FORK_DEATHSIG_SIGTERM | FORK_RLIMIT_NOFILE_SAFE | FORK_LOG,
&child_pid);
if (r < 0)
return r;
if (r == 0) {
/* In the child */
(void) exec_process(argv, fd, 1);
_exit(EXIT_FAILURE);
}
log_info("Spawned '%s' as PID " PID_FMT ".", joined, child_pid);
return 0;
}
static int do_accept(char * const *argv, int fd) {
_cleanup_free_ char *local = NULL, *peer = NULL;
_cleanup_close_ int fd_accepted = -EBADF;
fd_accepted = accept4(fd, NULL, NULL, 0);
if (fd_accepted < 0) {
if (ERRNO_IS_ACCEPT_AGAIN(errno))
return 0;
return log_error_errno(errno, "Failed to accept connection on fd:%d: %m", fd);
}
(void) getsockname_pretty(fd_accepted, &local);
(void) getpeername_pretty(fd_accepted, true, &peer);
log_info("Connection from %s to %s", strna(peer), strna(local));
return fork_and_exec_process(argv, fd_accepted);
}
/* SIGCHLD handler. */
static void sigchld_hdl(int sig) {
int r;
PROTECT_ERRNO;
for (;;) {
siginfo_t si = {};
r = waitid(P_ALL, 0, &si, WEXITED | WNOHANG);
if (r < 0) {
if (errno != ECHILD)
log_error_errno(errno, "Failed to reap children: %m");
return;
}
if (si.si_pid == 0)
return;
log_info("Child %d died with code %d", si.si_pid, si.si_status);
}
}
static int install_chld_handler(void) {
static const struct sigaction act = {
.sa_flags = SA_NOCLDSTOP | SA_RESTART,
.sa_handler = sigchld_hdl,
};
if (sigaction(SIGCHLD, &act, NULL) < 0)
return log_error_errno(errno, "Failed to install SIGCHLD handler: %m");
return 0;
}
static int help(void) {
_cleanup_free_ char *link = NULL;
int r;
r = terminal_urlify_man("systemd-socket-activate", "1", &link);
if (r < 0)
return log_oom();
printf("%s [OPTIONS...]\n"
"\n%sListen on sockets and launch child on connection.%s\n"
"\nOptions:\n"
" -h --help Show this help and exit\n"
" --version Print version string and exit\n"
" -l --listen=ADDR Listen for raw connections at ADDR\n"
" -d --datagram Listen on datagram instead of stream socket\n"
" --seqpacket Listen on SOCK_SEQPACKET instead of stream socket\n"
" -a --accept Spawn separate child for each connection\n"
" -E --setenv=NAME[=VALUE] Pass an environment variable to children\n"
" --fdname=NAME[:NAME...] Specify names for file descriptors\n"
" --inetd Enable inetd file descriptor passing protocol\n"
"\nNote: file descriptors from sd_listen_fds() will be passed through.\n"
"\nSee the %s for details.\n",
program_invocation_short_name,
ansi_highlight(),
ansi_normal(),
link);
return 0;
}
static int parse_argv(int argc, char *argv[]) {
enum {
ARG_VERSION = 0x100,
ARG_FDNAME,
ARG_SEQPACKET,
ARG_INETD,
};
static const struct option options[] = {
{ "help", no_argument, NULL, 'h' },
{ "version", no_argument, NULL, ARG_VERSION },
{ "datagram", no_argument, NULL, 'd' },
{ "seqpacket", no_argument, NULL, ARG_SEQPACKET },
{ "listen", required_argument, NULL, 'l' },
{ "accept", no_argument, NULL, 'a' },
{ "setenv", required_argument, NULL, 'E' },
{ "environment", required_argument, NULL, 'E' }, /* legacy alias */
{ "fdname", required_argument, NULL, ARG_FDNAME },
{ "inetd", no_argument, NULL, ARG_INETD },
{}
};
int c, r;
assert(argc >= 0);
assert(argv);
/* Resetting to 0 forces the invocation of an internal initialization routine of getopt_long()
* that checks for GNU extensions in optstring ('-' or '+' at the beginning). */
optind = 0;
while ((c = getopt_long(argc, argv, "+hl:aE:d", options, NULL)) >= 0)
switch (c) {
case 'h':
return help();
case ARG_VERSION:
return version();
case 'l':
r = strv_extend(&arg_listen, optarg);
if (r < 0)
return log_oom();
break;
case 'd':
if (arg_socket_type == SOCK_SEQPACKET)
return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
"--datagram may not be combined with --seqpacket.");
arg_socket_type = SOCK_DGRAM;
break;
case ARG_SEQPACKET:
if (arg_socket_type == SOCK_DGRAM)
return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
"--seqpacket may not be combined with --datagram.");
arg_socket_type = SOCK_SEQPACKET;
break;
case 'a':
arg_accept = true;
break;
case 'E':
r = strv_env_replace_strdup_passthrough(&arg_setenv, optarg);
if (r < 0)
return log_error_errno(r, "Cannot assign environment variable %s: %m", optarg);
break;
case ARG_FDNAME: {
_cleanup_strv_free_ char **names = NULL;
names = strv_split(optarg, ":");
if (!names)
return log_oom();
STRV_FOREACH(s, names)
if (!fdname_is_valid(*s)) {
_cleanup_free_ char *esc = NULL;
esc = cescape(*s);
log_warning("File descriptor name \"%s\" is not valid.", esc);
}
/* Empty optargs means one empty name */
r = strv_extend_strv(&arg_fdnames,
strv_isempty(names) ? STRV_MAKE("") : names,
false);
if (r < 0)
return log_error_errno(r, "strv_extend_strv: %m");
break;
}
case ARG_INETD:
arg_inetd = true;
break;
case '?':
return -EINVAL;
default:
assert_not_reached();
}
if (optind == argc)
return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
"%s: command to execute is missing.",
program_invocation_short_name);
if (arg_socket_type == SOCK_DGRAM && arg_accept)
return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
"Datagram sockets do not accept connections. "
"The --datagram and --accept options may not be combined.");
return 1 /* work to do */;
}
static int run(int argc, char **argv) {
_cleanup_close_ int epoll_fd = -EBADF;
_cleanup_strv_free_ char **exec_argv = NULL;
int r, n;
log_setup();
r = parse_argv(argc, argv);
if (r <= 0)
return r;
exec_argv = strv_copy(argv + optind);
if (!exec_argv)
return log_oom();
assert(!strv_isempty(exec_argv));
n = open_sockets(&epoll_fd);
if (n < 0)
return n;
if (n == 0)
return log_error_errno(SYNTHETIC_ERRNO(ENOENT), "No sockets to listen on specified or passed in.");
/* Notify the caller that all sockets are open now. We only do this in --accept mode however,
* since otherwise our process will be replaced and it's better to leave the readiness notify
* to the actual payload. */
_unused_ _cleanup_(notify_on_cleanup) const char *notify = NULL;
if (arg_accept) {
r = install_chld_handler();
if (r < 0)
return r;
notify = notify_start(NOTIFY_READY_MESSAGE, NOTIFY_STOPPING_MESSAGE);
}
for (;;) {
struct epoll_event event;
if (epoll_wait(epoll_fd, &event, 1, -1) < 0) {
if (errno == EINTR)
continue;
return log_error_errno(errno, "epoll_wait() failed: %m");
}
log_info("Communication attempt on fd %i.", event.data.fd);
if (!arg_accept)
return exec_process(exec_argv, SD_LISTEN_FDS_START, (size_t) n);
r = do_accept(exec_argv, event.data.fd);
if (r < 0)
return r;
}
}
DEFINE_MAIN_FUNCTION(run);
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