522 lines
17 KiB
C
522 lines
17 KiB
C
/* SPDX-License-Identifier: LGPL-2.1-or-later */
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#include <getopt.h>
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#include <sys/epoll.h>
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#include <sys/prctl.h>
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#include <sys/wait.h>
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#include <unistd.h>
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#include "sd-daemon.h"
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#include "alloc-util.h"
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#include "errno-util.h"
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#include "escape.h"
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#include "fd-util.h"
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#include "log.h"
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#include "macro.h"
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#include "pretty-print.h"
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#include "process-util.h"
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#include "signal-util.h"
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#include "socket-netlink.h"
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#include "socket-util.h"
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#include "string-util.h"
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#include "strv.h"
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#include "terminal-util.h"
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#include "util.h"
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static char **arg_listen = NULL;
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static bool arg_accept = false;
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static int arg_socket_type = SOCK_STREAM;
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static char **arg_args = NULL;
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static char **arg_setenv = NULL;
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static char **arg_fdnames = NULL;
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static bool arg_inetd = false;
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static int add_epoll(int epoll_fd, int fd) {
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struct epoll_event ev = {
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.events = EPOLLIN,
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.data.fd = fd,
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};
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assert(epoll_fd >= 0);
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assert(fd >= 0);
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if (epoll_ctl(epoll_fd, EPOLL_CTL_ADD, fd, &ev) < 0)
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return log_error_errno(errno, "Failed to add event on epoll fd:%d for fd:%d: %m", epoll_fd, fd);
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return 0;
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}
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static int open_sockets(int *epoll_fd, bool accept) {
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char **address;
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int n, fd, r, count = 0;
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n = sd_listen_fds(true);
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if (n < 0)
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return log_error_errno(n, "Failed to read listening file descriptors from environment: %m");
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if (n > 0) {
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log_info("Received %i descriptors via the environment.", n);
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for (fd = SD_LISTEN_FDS_START; fd < SD_LISTEN_FDS_START + n; fd++) {
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r = fd_cloexec(fd, arg_accept);
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if (r < 0)
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return r;
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count++;
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}
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}
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/* Close logging and all other descriptors */
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if (arg_listen) {
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_cleanup_free_ int *except = NULL;
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int i;
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except = new(int, n);
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if (!except)
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return log_oom();
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for (i = 0; i < n; i++)
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except[i] = SD_LISTEN_FDS_START + i;
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log_close();
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r = close_all_fds(except, n);
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if (r < 0)
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return log_error_errno(r, "Failed to close all file descriptors: %m");
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}
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/** Note: we leak some fd's on error here. I doesn't matter
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* much, since the program will exit immediately anyway, but
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* would be a pain to fix.
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*/
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STRV_FOREACH(address, arg_listen) {
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fd = make_socket_fd(LOG_DEBUG, *address, arg_socket_type, (arg_accept * SOCK_CLOEXEC));
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if (fd < 0) {
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log_open();
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return log_error_errno(fd, "Failed to open '%s': %m", *address);
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}
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assert(fd == SD_LISTEN_FDS_START + count);
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count++;
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}
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if (arg_listen)
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log_open();
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*epoll_fd = epoll_create1(EPOLL_CLOEXEC);
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if (*epoll_fd < 0)
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return log_error_errno(errno, "Failed to create epoll object: %m");
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for (fd = SD_LISTEN_FDS_START; fd < SD_LISTEN_FDS_START + count; fd++) {
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_cleanup_free_ char *name = NULL;
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getsockname_pretty(fd, &name);
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log_info("Listening on %s as %i.", strna(name), fd);
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r = add_epoll(*epoll_fd, fd);
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if (r < 0)
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return r;
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}
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return count;
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}
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static int exec_process(const char *name, char **argv, char **env, int start_fd, size_t n_fds) {
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_cleanup_strv_free_ char **envp = NULL;
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_cleanup_free_ char *joined = NULL;
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size_t n_env = 0, length;
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const char *tocopy;
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char **s;
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int r;
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if (arg_inetd && n_fds != 1)
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return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
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"--inetd only supported for single file descriptors.");
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length = strv_length(arg_setenv);
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/* PATH, TERM, HOME, USER, LISTEN_FDS, LISTEN_PID, LISTEN_FDNAMES, NULL */
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envp = new0(char *, length + 8);
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if (!envp)
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return log_oom();
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STRV_FOREACH(s, arg_setenv) {
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if (strchr(*s, '=')) {
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char *k;
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k = strdup(*s);
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if (!k)
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return log_oom();
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envp[n_env++] = k;
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} else {
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_cleanup_free_ char *p;
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const char *n;
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p = strjoin(*s, "=");
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if (!p)
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return log_oom();
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n = strv_find_prefix(env, p);
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if (!n)
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continue;
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envp[n_env] = strdup(n);
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if (!envp[n_env])
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return log_oom();
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n_env++;
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}
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}
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FOREACH_STRING(tocopy, "TERM=", "PATH=", "USER=", "HOME=") {
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const char *n;
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n = strv_find_prefix(env, tocopy);
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if (!n)
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continue;
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envp[n_env] = strdup(n);
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if (!envp[n_env])
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return log_oom();
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n_env++;
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}
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if (arg_inetd) {
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assert(n_fds == 1);
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r = rearrange_stdio(start_fd, start_fd, STDERR_FILENO); /* invalidates start_fd on success + error */
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if (r < 0)
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return log_error_errno(r, "Failed to move fd to stdin+stdout: %m");
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} else {
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if (start_fd != SD_LISTEN_FDS_START) {
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assert(n_fds == 1);
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if (dup2(start_fd, SD_LISTEN_FDS_START) < 0)
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return log_error_errno(errno, "Failed to dup connection: %m");
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safe_close(start_fd);
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}
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if (asprintf((char **) (envp + n_env++), "LISTEN_FDS=%zu", n_fds) < 0)
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return log_oom();
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if (asprintf((char **) (envp + n_env++), "LISTEN_PID=" PID_FMT, getpid_cached()) < 0)
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return log_oom();
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if (arg_fdnames) {
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_cleanup_free_ char *names = NULL;
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size_t len;
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char *e;
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len = strv_length(arg_fdnames);
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if (len == 1)
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for (size_t i = 1; i < n_fds; i++) {
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r = strv_extend(&arg_fdnames, arg_fdnames[0]);
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if (r < 0)
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return log_oom();
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}
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else if (len != n_fds)
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log_warning("The number of fd names is different than number of fds: %zu vs %zu", len, n_fds);
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names = strv_join(arg_fdnames, ":");
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if (!names)
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return log_oom();
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e = strjoin("LISTEN_FDNAMES=", names);
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if (!e)
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return log_oom();
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envp[n_env++] = e;
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}
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}
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joined = strv_join(argv, " ");
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if (!joined)
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return log_oom();
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log_info("Execing %s (%s)", name, joined);
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execvpe(name, argv, envp);
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return log_error_errno(errno, "Failed to execp %s (%s): %m", name, joined);
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}
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static int fork_and_exec_process(const char *child, char **argv, char **env, int fd) {
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_cleanup_free_ char *joined = NULL;
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pid_t child_pid;
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int r;
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joined = strv_join(argv, " ");
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if (!joined)
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return log_oom();
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r = safe_fork("(activate)",
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FORK_RESET_SIGNALS | FORK_DEATHSIG | FORK_RLIMIT_NOFILE_SAFE | FORK_LOG,
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&child_pid);
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if (r < 0)
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return r;
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if (r == 0) {
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/* In the child */
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exec_process(child, argv, env, fd, 1);
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_exit(EXIT_FAILURE);
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}
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log_info("Spawned %s (%s) as PID " PID_FMT ".", child, joined, child_pid);
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return 0;
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}
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static int do_accept(const char *name, char **argv, char **envp, int fd) {
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_cleanup_free_ char *local = NULL, *peer = NULL;
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_cleanup_close_ int fd_accepted = -1;
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fd_accepted = accept4(fd, NULL, NULL, 0);
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if (fd_accepted < 0) {
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if (ERRNO_IS_ACCEPT_AGAIN(errno))
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return 0;
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return log_error_errno(errno, "Failed to accept connection on fd:%d: %m", fd);
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}
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(void) getsockname_pretty(fd_accepted, &local);
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(void) getpeername_pretty(fd_accepted, true, &peer);
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log_info("Connection from %s to %s", strna(peer), strna(local));
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return fork_and_exec_process(name, argv, envp, fd_accepted);
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}
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/* SIGCHLD handler. */
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static void sigchld_hdl(int sig) {
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PROTECT_ERRNO;
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for (;;) {
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siginfo_t si;
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int r;
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si.si_pid = 0;
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r = waitid(P_ALL, 0, &si, WEXITED | WNOHANG);
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if (r < 0) {
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if (errno != ECHILD)
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log_error_errno(errno, "Failed to reap children: %m");
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return;
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}
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if (si.si_pid == 0)
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return;
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log_info("Child %d died with code %d", si.si_pid, si.si_status);
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}
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}
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static int install_chld_handler(void) {
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static const struct sigaction act = {
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.sa_flags = SA_NOCLDSTOP | SA_RESTART,
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.sa_handler = sigchld_hdl,
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};
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if (sigaction(SIGCHLD, &act, 0) < 0)
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return log_error_errno(errno, "Failed to install SIGCHLD handler: %m");
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return 0;
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}
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static int help(void) {
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_cleanup_free_ char *link = NULL;
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int r;
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r = terminal_urlify_man("systemd-socket-activate", "1", &link);
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if (r < 0)
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return log_oom();
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printf("%s [OPTIONS...]\n"
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"\n%sListen on sockets and launch child on connection.%s\n"
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"\nOptions:\n"
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" -h --help Show this help and exit\n"
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" --version Print version string and exit\n"
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" -l --listen=ADDR Listen for raw connections at ADDR\n"
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" -d --datagram Listen on datagram instead of stream socket\n"
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" --seqpacket Listen on SOCK_SEQPACKET instead of stream socket\n"
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" -a --accept Spawn separate child for each connection\n"
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" -E --setenv=NAME[=VALUE] Pass an environment variable to children\n"
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" --fdname=NAME[:NAME...] Specify names for file descriptors\n"
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" --inetd Enable inetd file descriptor passing protocol\n"
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"\nNote: file descriptors from sd_listen_fds() will be passed through.\n"
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"\nSee the %s for details.\n"
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, program_invocation_short_name
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, ansi_highlight(), ansi_normal()
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, link
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);
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return 0;
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}
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static int parse_argv(int argc, char *argv[]) {
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enum {
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ARG_VERSION = 0x100,
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ARG_FDNAME,
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ARG_SEQPACKET,
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ARG_INETD,
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};
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static const struct option options[] = {
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{ "help", no_argument, NULL, 'h' },
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{ "version", no_argument, NULL, ARG_VERSION },
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{ "datagram", no_argument, NULL, 'd' },
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{ "seqpacket", no_argument, NULL, ARG_SEQPACKET },
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{ "listen", required_argument, NULL, 'l' },
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{ "accept", no_argument, NULL, 'a' },
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{ "setenv", required_argument, NULL, 'E' },
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{ "environment", required_argument, NULL, 'E' }, /* legacy alias */
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{ "fdname", required_argument, NULL, ARG_FDNAME },
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{ "inetd", no_argument, NULL, ARG_INETD },
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{}
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};
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int c, r;
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assert(argc >= 0);
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assert(argv);
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while ((c = getopt_long(argc, argv, "+hl:aE:d", options, NULL)) >= 0)
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switch (c) {
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case 'h':
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return help();
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case ARG_VERSION:
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return version();
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case 'l':
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r = strv_extend(&arg_listen, optarg);
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if (r < 0)
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return log_oom();
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break;
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case 'd':
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if (arg_socket_type == SOCK_SEQPACKET)
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return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
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"--datagram may not be combined with --seqpacket.");
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arg_socket_type = SOCK_DGRAM;
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break;
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case ARG_SEQPACKET:
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if (arg_socket_type == SOCK_DGRAM)
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return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
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"--seqpacket may not be combined with --datagram.");
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arg_socket_type = SOCK_SEQPACKET;
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break;
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case 'a':
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arg_accept = true;
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break;
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case 'E':
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r = strv_extend(&arg_setenv, optarg);
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if (r < 0)
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return log_oom();
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break;
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case ARG_FDNAME: {
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_cleanup_strv_free_ char **names;
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char **s;
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names = strv_split(optarg, ":");
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if (!names)
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return log_oom();
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STRV_FOREACH(s, names)
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if (!fdname_is_valid(*s)) {
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_cleanup_free_ char *esc;
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esc = cescape(*s);
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log_warning("File descriptor name \"%s\" is not valid.", esc);
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}
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/* Empty optargs means one empty name */
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r = strv_extend_strv(&arg_fdnames,
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strv_isempty(names) ? STRV_MAKE("") : names,
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false);
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if (r < 0)
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return log_error_errno(r, "strv_extend_strv: %m");
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break;
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}
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case ARG_INETD:
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arg_inetd = true;
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break;
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case '?':
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return -EINVAL;
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default:
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assert_not_reached("Unhandled option");
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}
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if (optind == argc)
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return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
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"%s: command to execute is missing.",
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program_invocation_short_name);
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if (arg_socket_type == SOCK_DGRAM && arg_accept)
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return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
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"Datagram sockets do not accept connections. "
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"The --datagram and --accept options may not be combined.");
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arg_args = argv + optind;
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return 1 /* work to do */;
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}
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int main(int argc, char **argv, char **envp) {
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int r, n;
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int epoll_fd = -1;
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log_show_color(true);
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log_parse_environment();
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log_open();
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r = parse_argv(argc, argv);
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if (r <= 0)
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return r == 0 ? EXIT_SUCCESS : EXIT_FAILURE;
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r = install_chld_handler();
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if (r < 0)
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return EXIT_FAILURE;
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n = open_sockets(&epoll_fd, arg_accept);
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if (n < 0)
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return EXIT_FAILURE;
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if (n == 0) {
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log_error("No sockets to listen on specified or passed in.");
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return EXIT_FAILURE;
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}
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for (;;) {
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struct epoll_event event;
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if (epoll_wait(epoll_fd, &event, 1, -1) < 0) {
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if (errno == EINTR)
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continue;
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log_error_errno(errno, "epoll_wait() failed: %m");
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return EXIT_FAILURE;
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}
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log_info("Communication attempt on fd %i.", event.data.fd);
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if (arg_accept) {
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r = do_accept(argv[optind], argv + optind, envp, event.data.fd);
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if (r < 0)
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return EXIT_FAILURE;
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} else
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break;
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}
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exec_process(argv[optind], argv + optind, envp, SD_LISTEN_FDS_START, (size_t) n);
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return EXIT_SUCCESS;
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}
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