3 * daemon main program, collects request and forks handlers
5 * Copyright (C)1996-1997 Ian Jackson
7 * This is free software; you can redistribute it and/or modify it
8 * under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
12 * This program is distributed in the hope that it will be useful, but
13 * WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * General Public License for more details.
17 * You should have received a copy of the GNU General Public License
18 * along with userv; if not, write to the Free Software
19 * Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
31 #include <sys/types.h>
34 #include <sys/socket.h>
35 #include <sys/fcntl.h>
45 static pid_t checkpid= -1, detachpid= -1;
46 static sig_atomic_t needcheck= 1;
48 static void checkstalepipes(void) {
49 /* There is an unimportant race here. If there is a stale pipe but
50 * another pair of processes with the same pids is about to create a
51 * new one we can check that the pipe is stale before they recreate
52 * it but then only remove it afterwards; then we remove the pipe
53 * they're actually using causing that invocation to fail with
54 * ENOENT on the pipe. However, this can only happen if things are
55 * already shafted, because we check for stale pipes at startup
56 * before any children have been started, and then only when a child
57 * dies unhelpfully - and we actually have to have some stale pipes
58 * for the race to exist.
64 unsigned long timediff;
67 if (time(&now) == -1) { syslog(LOG_ERR,"get current time: %m"); return; }
69 if (!dir) { syslog(LOG_ERR,"open directory " VARDIR ": %m"); return; }
70 while ((de= readdir(dir))) {
71 if (fnmatch(PIPEPATTERN,de->d_name,FNM_PATHNAME|FNM_PERIOD)) continue;
72 r= lstat(de->d_name,&stab); if (r && errno==ENOENT) continue;
73 if (r) { syslog(LOG_ERR,"could not stat `" VARDIR "/%s': %m",de->d_name); continue; }
74 timediff= (unsigned long)now - (unsigned long)stab.st_ctime;
75 if (timediff >= (~0UL>>1) || timediff < 3600) continue;
76 if (unlink(de->d_name) && errno!=ENOENT)
77 syslog(LOG_ERR,"could not remove stale pipe `%s': %m",de->d_name);
79 if (closedir(dir)) syslog(LOG_ERR,"close directory " VARDIR ": %m");
82 static void sighandler_chld(int x) {
88 r= waitpid((pid_t)-1,&status,WNOHANG);
89 if (!r || (r==-1 && errno==ECHILD)) break;
90 if (r==-1) { syslog(LOG_ERR,"wait in sigchild handler gave error: %m"); break; }
92 if (WIFEXITED(status) && WEXITSTATUS(status)==4) _exit(4);
93 fprintf(stderr,"uservd: detaching child failed with unexpected code %d\n",status);
97 if (WIFEXITED(status)) {
98 if (!WEXITSTATUS(status)) {
99 syslog(LOG_WARNING,"no longer the uservd - exiting");
101 } else if (WEXITSTATUS(status)!=1) {
102 syslog(LOG_ERR,"check pid %ld exited with status %d",
103 (long)checkpid,WEXITSTATUS(status));
105 } else if (WIFSIGNALED(status)) {
106 if (WTERMSIG(status) == SIGALRM && !WCOREDUMP(status)) {
107 syslog(LOG_WARNING,"check timed out; no longer the uservd - exiting");
110 syslog(LOG_ERR,"check pid %ld %s due to signal %s",
112 WCOREDUMP(status) ? "dumped core" : "died",
113 strsignal(WTERMSIG(status)));
116 syslog(LOG_ERR,"check pid %ld died due to unknown reason, code %d",
117 (long)checkpid,status);
120 ar= alarm(USERVD_MYSELF_CHECK);
121 if (ar<0) { syslog(LOG_CRIT,"set alarm for next check: %m"); exit(5); }
123 if (WIFSIGNALED(status)) {
124 syslog(LOG_ERR,"call pid %ld %s due to signal %s",
126 WCOREDUMP(status) ? "dumped core" : "died",
127 strsignal(WTERMSIG(status)));
128 } else if (!WIFEXITED(status)) {
129 syslog(LOG_ERR,"call pid %ld died due to unknown reason, code %d",
131 } else if (WEXITSTATUS(status)>12) {
132 if (WEXITSTATUS(status)>24)
133 syslog(LOG_ERR,"call pid %ld exited with status %d >24",
134 (long)r,WEXITSTATUS(status));
143 static void sighandler_usr1(int x) {
147 static void sighandler_alrm(int x) {
151 static void sighandler_termint(int sig) {
152 syslog(LOG_NOTICE,"terminating due to signal %s",strsignal(sig));
156 static void blocksignals(int how) {
161 sigaddset(&set,SIGCHLD);
162 sigaddset(&set,SIGALRM);
163 sigaddset(&set,SIGTERM);
164 sigaddset(&set,SIGINT);
165 r= sigprocmask(how,&set,0); assert(!r);
168 static void NONRETURNING docheck(void) {
170 /* This subprocess exits with status 0 if the parent should die,
171 * 1 if it should not, and something else if it fails horribly.
175 struct opening_msg opening_mbuf;
176 struct request_msg request_mbuf;
177 unsigned long endmagic;
178 struct sigaction sig;
179 struct sockaddr_un ssockname;
181 openlog(USERVDCHECK_LOGIDENT,LOG_NDELAY|LOG_PID,USERVD_LOGFACILITY);
183 sigemptyset(&sig.sa_mask);
185 sig.sa_handler= SIG_IGN;
186 if (sigaction(SIGPIPE,&sig,0)) { syslog(LOG_ERR,"ignore sigpipe"); exit(1); }
188 sig.sa_handler= SIG_DFL;
189 if (sigaction(SIGALRM,&sig,0)) { syslog(LOG_ERR,"default sigalarm"); exit(1); }
191 sfd= socket(AF_UNIX,SOCK_STREAM,0);
192 if (!sfd) { syslog(LOG_ERR,"ignore sigpipe"); exit(1); }
194 assert(sizeof(ssockname.sun_path) > sizeof(RENDEZVOUS));
195 ssockname.sun_family= AF_UNIX;
196 strcpy(ssockname.sun_path,RENDEZVOUS);
198 r= connect(sfd,(struct sockaddr*)&ssockname,sizeof(ssockname));
200 if (errno == ECONNREFUSED || errno == ENOENT)
201 { syslog(LOG_WARNING,"real uservd daemon is not running: %m"); exit(0); }
202 syslog(LOG_ERR,"unable to connect to uservd daemon: %m"); exit(1);
205 r= alarm(USERVD_MYSELF_TIMEOUT);
206 if (r<0) { syslog(LOG_ERR,"set alarm for read: %m"); exit(1); }
207 remain= sizeof(opening_mbuf); p= (unsigned char*)&opening_mbuf;
209 r= read(sfd,p,remain);
210 if (r<0) { syslog(LOG_ERR,"read from server: %m"); exit(1); }
211 if (r==0) { syslog(LOG_ERR,"unexpected EOF from server"); exit(1); }
214 if (opening_mbuf.magic != OPENING_MAGIC) {
215 syslog(LOG_WARNING,"magic number mismatch");
218 if (memcmp(opening_mbuf.protocolchecksumversion,protocolchecksumversion,PCSUMSIZE)) {
219 syslog(LOG_WARNING,"protocol checksum mismatch");
222 if (opening_mbuf.overlordpid != overlordpid) {
223 syslog(LOG_WARNING,"overlord pid mismatch");
226 memset(&request_mbuf,0,sizeof(request_mbuf));
227 request_mbuf.magic= REQUEST_MAGIC;
228 request_mbuf.clientpid= -1;
229 request_mbuf.serviceuserlen= 0;
230 request_mbuf.servicelen= 0;
231 request_mbuf.lognamelen= 0;
232 request_mbuf.spoofed= 0;
233 request_mbuf.cwdlen= 0;
234 request_mbuf.overridelen= -1;
235 request_mbuf.callinguid= -1;
236 request_mbuf.ngids= 0;
237 request_mbuf.nreadfds= 0;
238 request_mbuf.nwritefds= 0;
239 request_mbuf.nargs= 0;
240 request_mbuf.nvars= 0;
241 r= write(sfd,&request_mbuf,sizeof(request_mbuf));
242 if (r==sizeof(request_mbuf)) {
243 endmagic= REQUEST_END_MAGIC;
244 write(sfd,&endmagic,sizeof(endmagic));
246 syslog(LOG_NOTICE,"uservd[%ld] is running",(long)overlordpid);
251 static void NONRETURNING startupsyscallerr(const char *what) {
253 "uservd: system call failed during startup:\n"
255 what,strerror(errno));
259 int main(int argc, char *const *argv) {
260 int mfd, sfd, nfd, csocklen, e, r, becomedaemon;
261 struct sigaction sigact;
262 struct sockaddr_un ssockname, csockname;
263 pid_t child, parentpid, sid;
266 abort(); /* Do not disable assertions in this security-critical code ! */
271 if (argv[1] && !strcmp(argv[1],"-daemon")) {
275 if (argc>1) { fputs("usage: uservd [-daemon]\n",stderr); exit(3); }
277 openlog(USERVD_LOGIDENT,LOG_NDELAY|LOG_PID,USERVD_LOGFACILITY);
279 if (chdir(VARDIR)) startupsyscallerr("cannot change to " VARDIR);
282 overlordpid= parentpid= getpid();
283 if (parentpid==-1) startupsyscallerr("cannot getpid");
285 mfd= socket(AF_UNIX,SOCK_STREAM,0);
286 if (mfd<0) startupsyscallerr("cannot create master socket");
288 assert(sizeof(ssockname.sun_path) > sizeof(RENDEZVOUS));
289 ssockname.sun_family= AF_UNIX;
290 strcpy(ssockname.sun_path,RENDEZVOUS);
292 r= bind(mfd,(struct sockaddr*)&ssockname,sizeof(ssockname));
293 if (r) startupsyscallerr("cannot bind master socket");
294 if (listen(mfd,5)) startupsyscallerr("cannot listen on master socket");
296 sigemptyset(&sigact.sa_mask);
297 sigaddset(&sigact.sa_mask,SIGCHLD);
298 sigaddset(&sigact.sa_mask,SIGALRM);
299 sigact.sa_flags= SA_NOCLDSTOP;
301 sigact.sa_handler= sighandler_chld;
302 if (sigaction(SIGCHLD,&sigact,0)) startupsyscallerr("cannot setup sigchld handler");
304 sigact.sa_handler= sighandler_alrm;
305 if (sigaction(SIGALRM,&sigact,0)) startupsyscallerr("cannot setup sigalrm handler");
308 sigact.sa_handler= sighandler_usr1;
309 if (sigaction(SIGUSR1,&sigact,0)) startupsyscallerr("cannot setup sigusr1 handler");
311 detachpid= fork(); if (detachpid==-1) startupsyscallerr("cannot fork to detach");
314 fputs("uservd: pause unexpectedly returned during detach\n",stderr);
317 sigact.sa_handler= SIG_DFL;
318 if (sigaction(SIGUSR1,&sigact,0)) startupsyscallerr("cannot restore sigusr1");
321 sigact.sa_handler= sighandler_termint;
322 if (sigaction(SIGTERM,&sigact,0)) startupsyscallerr("cannot setup sigterm handler");
323 if (sigaction(SIGINT,&sigact,0)) startupsyscallerr("cannot setup sigint handler");
326 nfd= open("/dev/null",O_RDWR);
327 if (nfd<0) startupsyscallerr("cannot open /dev/null");
328 sid= setsid(); if (sid == -1) startupsyscallerr("cannot create new session");
329 overlordpid= getpid();
330 if (overlordpid == -1) startupsyscallerr("getpid after detach");
331 if (dup2(nfd,0)<0 || dup2(nfd,1)<0)
332 startupsyscallerr("cannot dup /dev/null for stdin/out");
333 r= kill(parentpid,SIGUSR1); if (r) startupsyscallerr("send SIGUSR1 to detach");
335 if (r<0) { syslog(LOG_CRIT,"cannot dup /dev/null for stderr: %m"); exit(5); }
339 syslog(LOG_NOTICE,"started");
343 assert(checkpid==-1);
347 if (!checkpid) docheck();
349 } else if (errno==EAGAIN) {
350 syslog(LOG_ERR,"fork for check - will wait and retry: %m");
351 r= alarm(USERVD_CHECKFORK_RETRY);
352 if (r<0) { syslog(LOG_CRIT,"set alarm for retry check: %m"); exit(5); }
354 } else if (errno!=EINTR) {
355 syslog(LOG_CRIT,"fork for check: %m"); exit(5);
360 csocklen= sizeof(csockname);
361 blocksignals(SIG_UNBLOCK);
362 sfd= accept(mfd,(struct sockaddr*)&csockname,&csocklen);
364 blocksignals(SIG_BLOCK);
367 if (errno == EINTR) continue;
368 if (errno == ENOMEM || errno == EPROTO || errno == EAGAIN) {
369 syslog(LOG_ERR,"unable to accept connection: %m");
372 syslog(LOG_CRIT,"unable to accept new connections: %m");
376 child= nondebug_fork();
377 if (child == (pid_t)-1) {
378 syslog(LOG_ERR,"unable to fork server: %m");
385 blocksignals(SIG_UNBLOCK);