Daan De Meyer
a3b00f91bb
Whenever we're going to close all file descriptors, we tend to close the log and set it into open when needed mode. When this is done with the logging target set to LOG_TARGET_AUTO, we run into issues because for every logging call, we'll check if stderr is connected to the journal to determine where to send the logging message. This check obviously stops working when we close stderr, so we settle the log target before we do that so that we keep using the same logging target even after stderr is closed.
486 lines
16 KiB
C
486 lines
16 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 "build.h"
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#include "env-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 "main-func.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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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 *ret_epoll_fd, bool accept) {
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_cleanup_close_ int epoll_fd = -EBADF;
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int n, r, count = 0;
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assert(ret_epoll_fd);
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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 (int 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 = new(int, n);
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if (!except)
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return log_oom();
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for (int 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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log_set_open_when_needed(true);
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log_settle_target();
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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. It doesn't matter much, since the program will exit
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* immediately anyway, but would be a pain to fix. */
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STRV_FOREACH(address, arg_listen) {
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r = make_socket_fd(LOG_DEBUG, *address, arg_socket_type, (arg_accept * SOCK_CLOEXEC));
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if (r < 0)
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return log_error_errno(r, "Failed to open '%s': %m", *address);
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assert(r == 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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log_set_open_when_needed(false);
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}
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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 (int 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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*ret_epoll_fd = TAKE_FD(epoll_fd);
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return count;
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}
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static int exec_process(const char *name, char **argv, int start_fd, size_t n_fds) {
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_cleanup_strv_free_ char **envp = NULL;
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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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FOREACH_STRING(var, "TERM", "PATH", "USER", "HOME") {
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const char *n;
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n = strv_find_prefix(environ, var);
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if (!n)
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continue;
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r = strv_extend(&envp, n);
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if (r < 0)
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return r;
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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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r = strv_extendf(&envp, "LISTEN_FDS=%zu", n_fds);
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if (r < 0)
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return r;
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r = strv_extendf(&envp, "LISTEN_PID=" PID_FMT, getpid_cached());
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if (r < 0)
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return r;
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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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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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char *t = strjoin("LISTEN_FDNAMES=", names);
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if (!t)
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return log_oom();
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r = strv_consume(&envp, t);
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if (r < 0)
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return r;
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}
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}
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STRV_FOREACH(s, arg_setenv) {
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r = strv_env_replace_strdup(&envp, *s);
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if (r < 0)
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return r;
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}
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_cleanup_free_ char *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, 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, 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, int fd) {
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_cleanup_free_ char *local = NULL, *peer = NULL;
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_cleanup_close_ int fd_accepted = -EBADF;
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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, 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(),
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ansi_normal(),
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link);
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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_env_replace_strdup_passthrough(&arg_setenv, optarg);
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if (r < 0)
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return log_error_errno(r, "Cannot assign environment variable %s: %m", optarg);
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break;
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case ARG_FDNAME: {
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_cleanup_strv_free_ char **names = NULL;
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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 = NULL;
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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();
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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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static int run(int argc, char **argv) {
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_cleanup_close_ int epoll_fd = -EBADF;
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int r, n;
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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;
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r = install_chld_handler();
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if (r < 0)
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return r;
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n = open_sockets(&epoll_fd, arg_accept);
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if (n < 0)
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return n;
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if (n == 0)
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return log_error_errno(SYNTHETIC_ERRNO(ENOENT), "No sockets to listen on specified or passed in.");
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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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return log_error_errno(errno, "epoll_wait() failed: %m");
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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, event.data.fd);
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if (r < 0)
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return r;
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} else
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break;
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}
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return exec_process(argv[optind], argv + optind, SD_LISTEN_FDS_START, (size_t) n);
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}
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DEFINE_MAIN_FUNCTION(run);
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