emo/busybox
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity
3b69ba799f
busybox/debianutils/start_stop_daemon.c
Aitor Esteve Alvarado 7b6d4f50c9 start-stop-daemon: change priority before dropping privileges 
Currently start-stop-daemon fails when using both the -c option (set uid)
and -N option (set niceness/priority) as it first drops privileges and then
tries to increase the priority. This patch changes the order of execution.

Signed-off-by: Aitor Esteve Alvarado <aesteve@singularaircraft.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2019-06-09 13:47:49 +02:00

570 lines
17 KiB
C
Raw Blame History

/* vi: set sw=4 ts=4: */
/*
* Mini start-stop-daemon implementation(s) for busybox
*
* Written by Marek Michalkiewicz <marekm@i17linuxb.ists.pwr.wroc.pl>,
* Adapted for busybox David Kimdon <dwhedon@gordian.com>
*
* Licensed under GPLv2 or later, see file LICENSE in this source tree.
*/
/*
This is how it is supposed to work:
start-stop-daemon [OPTIONS] [--start|--stop] [[--] arguments...]
One (only) of these must be given:
-S,--start Start
-K,--stop Stop
Search for matching processes.
If --stop is given, stop all matching processes (by sending a signal).
If --start is given, start a new process unless a matching process was found.
Options controlling process matching
(if multiple conditions are specified, all must match):
-u,--user USERNAME|UID Only consider this user's processes
-n,--name PROCESS_NAME Look for processes by matching PROCESS_NAME
with comm field in /proc/$PID/stat.
Only basename is compared:
"ntpd" == "./ntpd" == "/path/to/ntpd".
[TODO: can PROCESS_NAME be a full pathname? Should we require full match then
with /proc/$PID/exe or argv[0] (comm can't be matched, it never contains path)]
-x,--exec EXECUTABLE Look for processes that were started with this
command in /proc/$PID/exe and /proc/$PID/cmdline
(/proc/$PID/cmdline is a bbox extension)
Unlike -n, we match against the full path:
"ntpd" != "./ntpd" != "/path/to/ntpd"
-p,--pidfile PID_FILE Look for processes with PID from this file
Options which are valid for --start only:
-x,--exec EXECUTABLE Program to run (1st arg of execvp). Mandatory.
-a,--startas NAME argv[0] (defaults to EXECUTABLE)
-b,--background Put process into background
-N,--nicelevel N Add N to process' nice level
-c,--chuid USER[:[GRP]] Change to specified user [and group]
-m,--make-pidfile Write PID to the pidfile
(both -m and -p must be given!)
Options which are valid for --stop only:
-s,--signal SIG Signal to send (default:TERM)
-t,--test Exit with status 0 if process is found
(we don't actually start or stop daemons)
Misc options:
-o,--oknodo Exit with status 0 if nothing is done
-q,--quiet Quiet
-v,--verbose Verbose
*/
//config:config START_STOP_DAEMON
//config: bool "start-stop-daemon (12 kb)"
//config: default y
//config: help
//config: start-stop-daemon is used to control the creation and
//config: termination of system-level processes, usually the ones
//config: started during the startup of the system.
//config:
//config:config FEATURE_START_STOP_DAEMON_LONG_OPTIONS
//config: bool "Enable long options"
//config: default y
//config: depends on START_STOP_DAEMON && LONG_OPTS
//config:
//config:config FEATURE_START_STOP_DAEMON_FANCY
//config: bool "Support additional arguments"
//config: default y
//config: depends on START_STOP_DAEMON
//config: help
//config: -o|--oknodo ignored since we exit with 0 anyway
//config: -v|--verbose
//config: -N|--nicelevel N
//applet:IF_START_STOP_DAEMON(APPLET_ODDNAME(start-stop-daemon, start_stop_daemon, BB_DIR_SBIN, BB_SUID_DROP, start_stop_daemon))
/* not NOEXEC: uses bb_common_bufsiz1 */
//kbuild:lib-$(CONFIG_START_STOP_DAEMON) += start_stop_daemon.o
//usage:#define start_stop_daemon_trivial_usage
//usage: "[OPTIONS] [-S|-K] ... [-- ARGS...]"
//usage:#define start_stop_daemon_full_usage "\n\n"
//usage: "Search for matching processes, and then\n"
//usage: "-K: stop all matching processes\n"
//usage: "-S: start a process unless a matching process is found\n"
//usage: "\nProcess matching:"
//usage: "\n -u USERNAME|UID Match only this user's processes"
//usage: "\n -n NAME Match processes with NAME"
//usage: "\n in comm field in /proc/PID/stat"
//usage: "\n -x EXECUTABLE Match processes with this command"
//usage: "\n in /proc/PID/cmdline"
//usage: "\n -p FILE Match a process with PID from FILE"
//usage: "\n All specified conditions must match"
//usage: "\n-S only:"
//usage: "\n -x EXECUTABLE Program to run"
//usage: "\n -a NAME Zeroth argument"
//usage: "\n -b Background"
//usage: IF_FEATURE_START_STOP_DAEMON_FANCY(
//usage: "\n -N N Change nice level"
//usage: )
//usage: "\n -c USER[:[GRP]] Change user/group"
//usage: "\n -m Write PID to pidfile specified by -p"
//usage: "\n-K only:"
//usage: "\n -s SIG Signal to send"
//usage: "\n -t Match only, exit with 0 if found"
//usage: "\nOther:"
//usage: IF_FEATURE_START_STOP_DAEMON_FANCY(
//usage: "\n -o Exit with status 0 if nothing is done"
//usage: "\n -v Verbose"
//usage: )
//usage: "\n -q Quiet"
/* Override ENABLE_FEATURE_PIDFILE */
#define WANT_PIDFILE 1
#include "libbb.h"
#include "common_bufsiz.h"
struct pid_list {
struct pid_list *next;
pid_t pid;
};
enum {
CTX_STOP = (1 << 0),
CTX_START = (1 << 1),
OPT_BACKGROUND = (1 << 2), // -b
OPT_QUIET = (1 << 3), // -q
OPT_TEST = (1 << 4), // -t
OPT_MAKEPID = (1 << 5), // -m
OPT_a = (1 << 6), // -a
OPT_n = (1 << 7), // -n
OPT_s = (1 << 8), // -s
OPT_u = (1 << 9), // -u
OPT_c = (1 << 10), // -c
OPT_x = (1 << 11), // -x
OPT_p = (1 << 12), // -p
OPT_OKNODO = (1 << 13) * ENABLE_FEATURE_START_STOP_DAEMON_FANCY, // -o
OPT_VERBOSE = (1 << 14) * ENABLE_FEATURE_START_STOP_DAEMON_FANCY, // -v
OPT_NICELEVEL = (1 << 15) * ENABLE_FEATURE_START_STOP_DAEMON_FANCY, // -N
};
#define QUIET (option_mask32 & OPT_QUIET)
#define TEST (option_mask32 & OPT_TEST)
struct globals {
struct pid_list *found_procs;
char *userspec;
char *cmdname;
char *execname;
char *pidfile;
char *execname_cmpbuf;
unsigned execname_sizeof;
int user_id;
smallint signal_nr;
#ifdef OLDER_VERSION_OF_X
struct stat execstat;
#endif
} FIX_ALIASING;
#define G (*(struct globals*)bb_common_bufsiz1)
#define userspec (G.userspec )
#define cmdname (G.cmdname )
#define execname (G.execname )
#define pidfile (G.pidfile )
#define user_id (G.user_id )
#define signal_nr (G.signal_nr )
#define INIT_G() do { \
setup_common_bufsiz(); \
user_id = -1; \
signal_nr = 15; \
} while (0)
#ifdef OLDER_VERSION_OF_X
/* -x,--exec EXECUTABLE
* Look for processes with matching /proc/$PID/exe.
* Match is performed using device+inode.
*/
static int pid_is_exec(pid_t pid)
{
struct stat st;
char buf[sizeof("/proc/%u/exe") + sizeof(int)*3];
sprintf(buf, "/proc/%u/exe", (unsigned)pid);
if (stat(buf, &st) < 0)
return 0;
if (st.st_dev == G.execstat.st_dev
&& st.st_ino == G.execstat.st_ino)
return 1;
return 0;
}
#else
static int pid_is_exec(pid_t pid)
{
ssize_t bytes;
char buf[sizeof("/proc/%u/cmdline") + sizeof(int)*3];
char *procname, *exelink;
int match;
procname = buf + sprintf(buf, "/proc/%u/exe", (unsigned)pid) - 3;
exelink = xmalloc_readlink(buf);
match = (exelink && strcmp(execname, exelink) == 0);
free(exelink);
if (match)
return match;
strcpy(procname, "cmdline");
bytes = open_read_close(buf, G.execname_cmpbuf, G.execname_sizeof);
if (bytes > 0) {
G.execname_cmpbuf[bytes] = '\0';
return strcmp(execname, G.execname_cmpbuf) == 0;
}
return 0;
}
#endif
static int pid_is_name(pid_t pid)
{
/* /proc/PID/stat is "PID (comm_15_bytes_max) ..." */
char buf[32]; /* should be enough */
char *p, *pe;
sprintf(buf, "/proc/%u/stat", (unsigned)pid);
if (open_read_close(buf, buf, sizeof(buf) - 1) < 0)
return 0;
buf[sizeof(buf) - 1] = '\0'; /* paranoia */
p = strchr(buf, '(');
if (!p)
return 0;
pe = strrchr(++p, ')');
if (!pe)
return 0;
*pe = '\0';
/* we require comm to match and to not be truncated */
/* in Linux, if comm is 15 chars, it may be a truncated
* name, so we don't allow that to match */
if (strlen(p) >= COMM_LEN - 1) /* COMM_LEN is 16 */
return 0;
return strcmp(p, cmdname) == 0;
}
static int pid_is_user(int pid)
{
struct stat sb;
char buf[sizeof("/proc/") + sizeof(int)*3];
sprintf(buf, "/proc/%u", (unsigned)pid);
if (stat(buf, &sb) != 0)
return 0;
return (sb.st_uid == (uid_t)user_id);
}
static void check(int pid)
{
struct pid_list *p;
if (execname && !pid_is_exec(pid)) {
return;
}
if (cmdname && !pid_is_name(pid)) {
return;
}
if (userspec && !pid_is_user(pid)) {
return;
}
p = xmalloc(sizeof(*p));
p->next = G.found_procs;
p->pid = pid;
G.found_procs = p;
}
static void do_pidfile(void)
{
FILE *f;
unsigned pid;
f = fopen_for_read(pidfile);
if (f) {
if (fscanf(f, "%u", &pid) == 1)
check(pid);
fclose(f);
} else if (errno != ENOENT)
bb_perror_msg_and_die("open pidfile %s", pidfile);
}
static void do_procinit(void)
{
DIR *procdir;
struct dirent *entry;
int pid;
if (pidfile) {
do_pidfile();
return;
}
procdir = xopendir("/proc");
pid = 0;
while (1) {
errno = 0; /* clear any previous error */
entry = readdir(procdir);
// TODO: this check is too generic, it's better
// to check for exact errno(s) which mean that we got stale entry
if (errno) /* Stale entry, process has died after opendir */
continue;
if (!entry) /* EOF, no more entries */
break;
pid = bb_strtou(entry->d_name, NULL, 10);
if (errno) /* NaN */
continue;
check(pid);
}
closedir(procdir);
if (!pid)
bb_error_msg_and_die("nothing in /proc - not mounted?");
}
static int do_stop(void)
{
char *what;
struct pid_list *p;
int killed = 0;
if (cmdname) {
if (ENABLE_FEATURE_CLEAN_UP) what = xstrdup(cmdname);
if (!ENABLE_FEATURE_CLEAN_UP) what = cmdname;
} else if (execname) {
if (ENABLE_FEATURE_CLEAN_UP) what = xstrdup(execname);
if (!ENABLE_FEATURE_CLEAN_UP) what = execname;
} else if (pidfile) {
what = xasprintf("process in pidfile '%s'", pidfile);
} else if (userspec) {
what = xasprintf("process(es) owned by '%s'", userspec);
} else {
bb_error_msg_and_die("internal error, please report");
}
if (!G.found_procs) {
if (!QUIET)
printf("no %s found; none killed\n", what);
killed = -1;
goto ret;
}
for (p = G.found_procs; p; p = p->next) {
if (kill(p->pid, TEST ? 0 : signal_nr) == 0) {
killed++;
} else {
bb_perror_msg("warning: killing process %u", (unsigned)p->pid);
p->pid = 0;
if (TEST) {
/* Example: -K --test --pidfile PIDFILE detected
* that PIDFILE's pid doesn't exist */
killed = -1;
goto ret;
}
}
}
if (!QUIET && killed) {
printf("stopped %s (pid", what);
for (p = G.found_procs; p; p = p->next)
if (p->pid)
printf(" %u", (unsigned)p->pid);
puts(")");
}
ret:
if (ENABLE_FEATURE_CLEAN_UP)
free(what);
return killed;
}
#if ENABLE_FEATURE_START_STOP_DAEMON_LONG_OPTIONS
static const char start_stop_daemon_longopts[] ALIGN1 =
"stop\0" No_argument "K"
"start\0" No_argument "S"
"background\0" No_argument "b"
"quiet\0" No_argument "q"
"test\0" No_argument "t"
"make-pidfile\0" No_argument "m"
# if ENABLE_FEATURE_START_STOP_DAEMON_FANCY
"oknodo\0" No_argument "o"
"verbose\0" No_argument "v"
"nicelevel\0" Required_argument "N"
# endif
"startas\0" Required_argument "a"
"name\0" Required_argument "n"
"signal\0" Required_argument "s"
"user\0" Required_argument "u"
"chuid\0" Required_argument "c"
"exec\0" Required_argument "x"
"pidfile\0" Required_argument "p"
# if ENABLE_FEATURE_START_STOP_DAEMON_FANCY
"retry\0" Required_argument "R"
# endif
;
# define GETOPT32 getopt32long
# define LONGOPTS start_stop_daemon_longopts,
#else
# define GETOPT32 getopt32
# define LONGOPTS
#endif
int start_stop_daemon_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int start_stop_daemon_main(int argc UNUSED_PARAM, char **argv)
{
unsigned opt;
char *signame;
char *startas = NULL;
char *chuid;
#if ENABLE_FEATURE_START_STOP_DAEMON_FANCY
// char *retry_arg = NULL;
// int retries = -1;
char *opt_N;
#endif
INIT_G();
opt = GETOPT32(argv, "^"
"KSbqtma:n:s:u:c:x:p:"
IF_FEATURE_START_STOP_DAEMON_FANCY("ovN:R:")
/* -K or -S is required; they are mutually exclusive */
/* -p is required if -m is given */
/* -xpun (at least one) is required if -K is given */
// /* -xa (at least one) is required if -S is given */
//WRONG: "start-stop-daemon -S -- sleep 5" is a valid invocation
/* -q turns off -v */
"\0"
"K:S:K--S:S--K:m?p:K?xpun"
IF_FEATURE_START_STOP_DAEMON_FANCY("q-v"),
LONGOPTS
&startas, &cmdname, &signame, &userspec, &chuid, &execname, &pidfile
IF_FEATURE_START_STOP_DAEMON_FANCY(,&opt_N)
/* We accept and ignore -R <param> / --retry <param> */
IF_FEATURE_START_STOP_DAEMON_FANCY(,NULL)
);
if (opt & OPT_s) {
signal_nr = get_signum(signame);
if (signal_nr < 0) bb_show_usage();
}
//argc -= optind;
argv += optind;
// ARGS contains zeroth arg if -x/-a is not given, else it starts with 1st arg.
// These will try to execute "[/bin/]sleep 5":
// "start-stop-daemon -S -- sleep 5"
// "start-stop-daemon -S -x /bin/sleep -- 5"
// "start-stop-daemon -S -a sleep -- 5"
// NB: -n option does _not_ behave in this way: this will try to execute "5":
// "start-stop-daemon -S -n sleep -- 5"
if (opt & CTX_START) {
if (!execname) { /* -x is not given */
execname = startas;
if (!execname) { /* neither -x nor -a is given */
execname = argv[0];
if (!execname)
bb_show_usage();
argv++;
}
}
if (!startas) /* -a is not given: use -x EXECUTABLE or argv[0] */
startas = execname;
*--argv = startas;
}
if (execname) {
G.execname_sizeof = strlen(execname) + 1;
G.execname_cmpbuf = xmalloc(G.execname_sizeof + 1);
}
// IF_FEATURE_START_STOP_DAEMON_FANCY(
// if (retry_arg)
// retries = xatoi_positive(retry_arg);
// )
if (userspec) {
user_id = bb_strtou(userspec, NULL, 10);
if (errno)
user_id = xuname2uid(userspec);
}
/* Both start and stop need to know current processes */
do_procinit();
if (opt & CTX_STOP) {
int i = do_stop();
return (opt & OPT_OKNODO) ? 0 : (i <= 0);
}
/* else: CTX_START (-S). execname can't be NULL. */
if (G.found_procs) {
if (!QUIET)
printf("%s is already running\n", execname);
return !(opt & OPT_OKNODO);
}
#ifdef OLDER_VERSION_OF_X
if (execname)
xstat(execname, &G.execstat);
#endif
if (opt & OPT_BACKGROUND) {
/* Daemons usually call bb_daemonize_or_rexec(), but SSD can do
* without: SSD is not itself a daemon, it _execs_ a daemon.
* The usual NOMMU problem of "child can't run indefinitely,
* it must exec" does not bite us: we exec anyway.
*
* bb_daemonize(DAEMON_DEVNULL_STDIO | DAEMON_CLOSE_EXTRA_FDS | DAEMON_DOUBLE_FORK)
* can be used on MMU systems, but use of vfork()
* is preferable since we want to create pidfile
* _before_ parent returns, and vfork() on Linux
* ensures that (by blocking parent until exec in the child).
*/
pid_t pid = xvfork();
if (pid != 0) {
/* Parent */
/* why _exit? the child may have changed the stack,
* so "return 0" may do bad things
*/
_exit(EXIT_SUCCESS);
}
/* Child */
setsid(); /* detach from controlling tty */
/* Redirect stdio to /dev/null, close extra FDs */
bb_daemon_helper(DAEMON_DEVNULL_STDIO + DAEMON_CLOSE_EXTRA_FDS);
/* On Linux, session leader can acquire ctty
* unknowingly, by opening a tty.
* Prevent this: stop being a session leader.
*/
pid = xvfork();
if (pid != 0)
_exit(EXIT_SUCCESS); /* Parent */
}
if (opt & OPT_MAKEPID) {
/* User wants _us_ to make the pidfile */
write_pidfile(pidfile);
}
#if ENABLE_FEATURE_START_STOP_DAEMON_FANCY
if (opt & OPT_NICELEVEL) {
/* Set process priority (must be before OPT_c) */
int prio = getpriority(PRIO_PROCESS, 0) + xatoi_range(opt_N, INT_MIN/2, INT_MAX/2);
if (setpriority(PRIO_PROCESS, 0, prio) < 0) {
bb_perror_msg_and_die("setpriority(%d)", prio);
}
}
#endif
if (opt & OPT_c) {
struct bb_uidgid_t ugid;
parse_chown_usergroup_or_die(&ugid, chuid);
if (ugid.uid != (uid_t) -1L) {
struct passwd *pw = xgetpwuid(ugid.uid);
if (ugid.gid != (gid_t) -1L)
pw->pw_gid = ugid.gid;
/* initgroups, setgid, setuid: */
change_identity(pw);
} else if (ugid.gid != (gid_t) -1L) {
xsetgid(ugid.gid);
setgroups(1, &ugid.gid);
}
}
/* Try:
* strace -oLOG start-stop-daemon -S -x /bin/usleep -a qwerty 500000
* should exec "/bin/usleep", but argv[0] should be "qwerty":
*/
execvp(execname, argv);
bb_perror_msg_and_die("can't execute '%s'", startas);
}
Reference in New Issue View Git Blame Copy Permalink