4f07ddfa9b
This adds the sd_notify_barrier function, to allow users to synchronize against the reception of sd_notify(3) status messages. It acts as a synchronization point, and a successful return gurantees that all previous messages have been consumed by the manager. This can be used to eliminate race conditions where the sending process exits too early for systemd to associate its PID to a cgroup and attribute the status message to a unit correctly. systemd-notify now uses this function for proper notification delivery and be useful for NotifyAccess=all units again in user mode, or in cases where it doesn't have a control process as parent. Fixes: #2739
282 lines
9.3 KiB
C
282 lines
9.3 KiB
C
/* SPDX-License-Identifier: LGPL-2.1+ */
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#include <errno.h>
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#include <getopt.h>
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#include <stdio.h>
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#include <stdlib.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 "env-util.h"
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#include "format-util.h"
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#include "log.h"
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#include "main-func.h"
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#include "parse-util.h"
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#include "pretty-print.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 "time-util.h"
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#include "user-util.h"
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#include "util.h"
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static bool arg_ready = false;
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static pid_t arg_pid = 0;
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static const char *arg_status = NULL;
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static bool arg_booted = false;
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static uid_t arg_uid = UID_INVALID;
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static gid_t arg_gid = GID_INVALID;
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static bool arg_no_block = false;
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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-notify", "1", &link);
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if (r < 0)
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return log_oom();
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printf("%s [OPTIONS...] [VARIABLE=VALUE...]\n"
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"\n%sNotify the init system about service status updates.%s\n\n"
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" -h --help Show this help\n"
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" --version Show package version\n"
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" --ready Inform the init system about service start-up completion\n"
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" --pid[=PID] Set main PID of daemon\n"
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" --uid=USER Set user to send from\n"
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" --status=TEXT Set status text\n"
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" --booted Check if the system was booted up with systemd\n"
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" --no-block Do not wait until operation finished\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 pid_t manager_pid(void) {
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const char *e;
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pid_t pid;
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int r;
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/* If we run as a service managed by systemd --user the $MANAGERPID environment variable points to
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* the service manager's PID. */
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e = getenv("MANAGERPID");
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if (!e)
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return 0;
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r = parse_pid(e, &pid);
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if (r < 0) {
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log_warning_errno(r, "$MANAGERPID is set to an invalid PID, ignoring: %s", e);
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return 0;
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}
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return pid;
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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_READY = 0x100,
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ARG_VERSION,
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ARG_PID,
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ARG_STATUS,
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ARG_BOOTED,
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ARG_UID,
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ARG_NO_BLOCK
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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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{ "ready", no_argument, NULL, ARG_READY },
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{ "pid", optional_argument, NULL, ARG_PID },
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{ "status", required_argument, NULL, ARG_STATUS },
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{ "booted", no_argument, NULL, ARG_BOOTED },
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{ "uid", required_argument, NULL, ARG_UID },
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{ "no-block", no_argument, NULL, ARG_NO_BLOCK },
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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, "h", 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 ARG_READY:
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arg_ready = true;
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break;
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case ARG_PID:
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if (isempty(optarg) || streq(optarg, "auto")) {
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arg_pid = getppid();
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if (arg_pid <= 1 ||
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arg_pid == manager_pid()) /* Don't send from PID 1 or the service
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* manager's PID (which might be distinct from
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* 1, if we are a --user instance), that'd just
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* be confusing for the service manager */
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arg_pid = getpid();
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} else if (streq(optarg, "parent"))
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arg_pid = getppid();
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else if (streq(optarg, "self"))
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arg_pid = getpid();
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else {
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r = parse_pid(optarg, &arg_pid);
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if (r < 0)
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return log_error_errno(r, "Failed to parse PID %s.", optarg);
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}
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break;
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case ARG_STATUS:
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arg_status = optarg;
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break;
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case ARG_BOOTED:
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arg_booted = true;
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break;
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case ARG_UID: {
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const char *u = optarg;
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r = get_user_creds(&u, &arg_uid, &arg_gid, NULL, NULL, 0);
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if (r == -ESRCH) /* If the user doesn't exist, then accept it anyway as numeric */
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r = parse_uid(u, &arg_uid);
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if (r < 0)
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return log_error_errno(r, "Can't resolve user %s: %m", optarg);
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break;
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}
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case ARG_NO_BLOCK:
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arg_no_block = 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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}
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if (optind >= argc &&
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!arg_ready &&
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!arg_status &&
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!arg_pid &&
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!arg_booted) {
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help();
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return -EINVAL;
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}
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return 1;
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}
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static int run(int argc, char* argv[]) {
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_cleanup_free_ char *status = NULL, *cpid = NULL, *n = NULL;
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_cleanup_strv_free_ char **final_env = NULL;
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char* our_env[4];
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unsigned i = 0;
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pid_t source_pid;
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int r;
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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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if (arg_booted)
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return sd_booted() <= 0;
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if (arg_ready)
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our_env[i++] = (char*) "READY=1";
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if (arg_status) {
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status = strjoin("STATUS=", arg_status);
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if (!status)
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return log_oom();
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our_env[i++] = status;
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}
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if (arg_pid > 0) {
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if (asprintf(&cpid, "MAINPID="PID_FMT, arg_pid) < 0)
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return log_oom();
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our_env[i++] = cpid;
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}
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our_env[i++] = NULL;
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final_env = strv_env_merge(2, our_env, argv + optind);
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if (!final_env)
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return log_oom();
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if (strv_isempty(final_env))
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return 0;
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n = strv_join(final_env, "\n");
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if (!n)
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return log_oom();
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/* If this is requested change to the requested UID/GID. Note that we only change the real UID here, and leave
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the effective UID in effect (which is 0 for this to work). That's because we want the privileges to fake the
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ucred data, and sd_pid_notify() uses the real UID for filling in ucred. */
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if (arg_gid != GID_INVALID &&
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setregid(arg_gid, (gid_t) -1) < 0)
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return log_error_errno(errno, "Failed to change GID: %m");
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if (arg_uid != UID_INVALID &&
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setreuid(arg_uid, (uid_t) -1) < 0)
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return log_error_errno(errno, "Failed to change UID: %m");
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if (arg_pid > 0)
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source_pid = arg_pid;
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else {
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/* Pretend the message originates from our parent, given that we are typically called from a
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* shell script, i.e. we are not the main process of a service but only a child of it. */
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source_pid = getppid();
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if (source_pid <= 1 ||
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source_pid == manager_pid()) /* safety check: don't claim we'd send anything from PID 1
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* or the service manager itself */
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source_pid = 0;
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}
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r = sd_pid_notify(source_pid, false, n);
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if (r < 0)
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return log_error_errno(r, "Failed to notify init system: %m");
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if (r == 0)
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return log_error_errno(SYNTHETIC_ERRNO(EOPNOTSUPP),
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"No status data could be sent: $NOTIFY_SOCKET was not set");
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if (!arg_no_block) {
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r = sd_notify_barrier(0, 5 * USEC_PER_SEC);
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if (r < 0)
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return log_error_errno(r, "Failed to invoke barrier: %m");
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if (r == 0)
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return log_error_errno(SYNTHETIC_ERRNO(EOPNOTSUPP),
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"No status data could be sent: $NOTIFY_SOCKET was not set");
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}
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return 0;
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}
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DEFINE_MAIN_FUNCTION(run);
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