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systemd/src/activate/activate.c
Zbigniew Jędrzejewski-Szmek 76e68b3db3 activate: simplify/rework implementation of --setenv 
Previous implementation is simplified by using the new helper. The new code
does more looping, but considering that it's unlikely that people set more
than a handful of variables through commandline options, this should be OK.

If a variable is specified on the command line, it overrides any automatically
set variable. Effective behaviour was already were like this, because we would
specify two variables, both would be set, and since glibc will return
the first matching entry.
('systemd-socket-activate -E TERM=FOO -l 2000 --inetd -a env' would give
'TERM=FOO TERM=xterm-256color PATH=...', and getenv("TERM") returns "FOO".)
But it's nicer to filter out any duplicate entries and only pass the intended
variable to the child process.
2021-08-11 10:17:50 +02:00

490 lines
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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 "env-util.h"
#include "errno-util.h"
#include "escape.h"
#include "fd-util.h"
#include "log.h"
#include "macro.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"
#include "util.h"
static char **arg_listen = NULL;
static bool arg_accept = false;
static int arg_socket_type = SOCK_STREAM;
static char **arg_args = NULL;
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 *epoll_fd, bool accept) {
char **address;
int n, fd, r, count = 0;
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 (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 = NULL;
int i;
except = new(int, n);
if (!except)
return log_oom();
for (i = 0; i < n; i++)
except[i] = SD_LISTEN_FDS_START + i;
log_close();
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. I doesn't matter
* much, since the program will exit immediately anyway, but
* would be a pain to fix.
*/
STRV_FOREACH(address, arg_listen) {
fd = make_socket_fd(LOG_DEBUG, *address, arg_socket_type, (arg_accept * SOCK_CLOEXEC));
if (fd < 0) {
log_open();
return log_error_errno(fd, "Failed to open '%s': %m", *address);
}
assert(fd == SD_LISTEN_FDS_START + count);
count++;
}
if (arg_listen)
log_open();
*epoll_fd = epoll_create1(EPOLL_CLOEXEC);
if (*epoll_fd < 0)
return log_error_errno(errno, "Failed to create epoll object: %m");
for (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;
}
return count;
}
static int exec_process(const char *name, char **argv, int start_fd, size_t n_fds) {
_cleanup_strv_free_ char **envp = NULL;
const char *var;
char **s;
int r;
if (arg_inetd && n_fds != 1)
return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
"--inetd only supported for single file descriptors.");
FOREACH_STRING(var, "TERM", "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("Execing %s (%s)", name, joined);
execvpe(name, argv, envp);
return log_error_errno(errno, "Failed to execp %s (%s): %m", name, joined);
}
static int fork_and_exec_process(const char *child, char **argv, int fd) {
_cleanup_free_ char *joined = NULL;
pid_t child_pid;
int r;
joined = strv_join(argv, " ");
if (!joined)
return log_oom();
r = safe_fork("(activate)",
FORK_RESET_SIGNALS | FORK_DEATHSIG | FORK_RLIMIT_NOFILE_SAFE | FORK_LOG,
&child_pid);
if (r < 0)
return r;
if (r == 0) {
/* In the child */
exec_process(child, argv, fd, 1);
_exit(EXIT_FAILURE);
}
log_info("Spawned %s (%s) as PID " PID_FMT ".", child, joined, child_pid);
return 0;
}
static int do_accept(const char *name, char **argv, int fd) {
_cleanup_free_ char *local = NULL, *peer = NULL;
_cleanup_close_ int fd_accepted = -1;
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(name, argv, fd_accepted);
}
/* SIGCHLD handler. */
static void sigchld_hdl(int sig) {
PROTECT_ERRNO;
for (;;) {
siginfo_t si;
int r;
si.si_pid = 0;
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, 0) < 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);
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;
char **s;
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.");
arg_args = argv + optind;
return 1 /* work to do */;
}
int main(int argc, char **argv) {
int r, n;
int epoll_fd = -1;
log_show_color(true);
log_parse_environment();
log_open();
r = parse_argv(argc, argv);
if (r <= 0)
return r == 0 ? EXIT_SUCCESS : EXIT_FAILURE;
r = install_chld_handler();
if (r < 0)
return EXIT_FAILURE;
n = open_sockets(&epoll_fd, arg_accept);
if (n < 0)
return EXIT_FAILURE;
if (n == 0) {
log_error("No sockets to listen on specified or passed in.");
return EXIT_FAILURE;
}
for (;;) {
struct epoll_event event;
if (epoll_wait(epoll_fd, &event, 1, -1) < 0) {
if (errno == EINTR)
continue;
log_error_errno(errno, "epoll_wait() failed: %m");
return EXIT_FAILURE;
}
log_info("Communication attempt on fd %i.", event.data.fd);
if (arg_accept) {
r = do_accept(argv[optind], argv + optind, event.data.fd);
if (r < 0)
return EXIT_FAILURE;
} else
break;
}
exec_process(argv[optind], argv + optind, SD_LISTEN_FDS_START, (size_t) n);
return EXIT_SUCCESS;
}
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