3 * daemon main program, collects request and forks handlers
6 * Copyright 1996-2017 Ian Jackson <ian@davenant.greenend.org.uk>.
7 * Copyright 2000 Ben Harris <bjh21@cam.ac.uk>
8 * Copyright 2016-2017 Peter Benie <pjb1008@cam.ac.uk>
10 * This is free software; you can redistribute it and/or modify it
11 * under the terms of the GNU General Public License as published by
12 * the Free Software Foundation; either version 3 of the License, or
13 * (at your option) any later version.
15 * This program is distributed in the hope that it will be useful, but
16 * WITHOUT ANY WARRANTY; without even the implied warranty of
17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
18 * General Public License for more details.
20 * You should have received a copy of the GNU General Public License
21 * along with userv; if not, see <http://www.gnu.org/licenses/>.
34 #include <sys/types.h>
36 #include <sys/socket.h>
48 static pid_t checkpid= -1, detachpid= -1;
49 static sig_atomic_t needcheck= 1; /* 2 means we half-expect the server to be down */
51 static void checkstalepipes(void) {
52 /* There is an unimportant race here. If there is a stale pipe but
53 * another pair of processes with the same pids is about to create a
54 * new one we can check that the pipe is stale before they recreate
55 * it but then only remove it afterwards; then we remove the pipe
56 * they're actually using causing that invocation to fail with
57 * ENOENT on the pipe. However, this can only happen if things are
58 * already shafted, because we check for stale pipes at startup
59 * before any children have been started, and then only when a child
60 * dies unhelpfully - and we actually have to have some stale pipes
61 * for the race to exist.
67 unsigned long timediff;
70 if (time(&now) == -1) { syslog(LOG_ERR,"get current time: %m"); return; }
72 if (!dir) { syslog(LOG_ERR,"open directory " VARDIR ": %m"); return; }
73 while ((errno=0, de= readdir(dir))) {
74 if (fnmatch(PIPEPATTERN,de->d_name,FNM_PATHNAME|FNM_PERIOD)) continue;
75 r= lstat(de->d_name,&stab); if (r && errno==ENOENT) continue;
76 if (r) { syslog(LOG_ERR,"could not stat `" VARDIR "/%s': %m",de->d_name); continue; }
77 timediff= (unsigned long)now - (unsigned long)stab.st_ctime;
78 if (timediff >= (~0UL>>1) || timediff < 3600) continue;
79 if (unlink(de->d_name) && errno!=ENOENT)
80 syslog(LOG_ERR,"could not remove stale pipe `%s': %m",de->d_name);
82 if (errno) syslog(LOG_ERR,"read directory " VARDIR ": %m");
83 if (closedir(dir)) syslog(LOG_ERR,"close directory " VARDIR ": %m");
86 static void sighandler_chld(int x) {
92 r= waitpid((pid_t)-1,&status,WNOHANG);
93 if (!r || (r==-1 && errno==ECHILD)) break;
94 if (r==-1) { syslog(LOG_ERR,"wait in sigchild handler gave error: %m"); break; }
96 if (WIFEXITED(status) && WEXITSTATUS(status)==4) _exit(4);
97 fprintf(stderr,"uservd: detaching child failed with unexpected code %d\n",status);
101 if (WIFEXITED(status)) {
102 if (!WEXITSTATUS(status)) {
103 syslog(LOG_WARNING,"no longer the uservd - exiting");
105 } else if (WEXITSTATUS(status)!=1) {
106 syslog(LOG_ERR,"check pid %ld exited with status %d",
107 (long)checkpid,WEXITSTATUS(status));
109 } else if (WIFSIGNALED(status)) {
110 if (WTERMSIG(status) == SIGALRM && !WCOREDUMP(status)) {
111 syslog(LOG_WARNING,"check timed out; no longer the uservd - exiting");
114 syslog(LOG_ERR,"check pid %ld %s due to signal %s",
116 WCOREDUMP(status) ? "dumped core" : "died",
117 strsignal(WTERMSIG(status)));
120 syslog(LOG_ERR,"check pid %ld died due to unknown reason, code %d",
121 (long)checkpid,status);
124 alarm(USERVD_MYSELF_CHECK);
126 if (WIFSIGNALED(status)) {
127 syslog(LOG_ERR,"call pid %ld %s due to signal %s",
129 WCOREDUMP(status) ? "dumped core" : "died",
130 strsignal(WTERMSIG(status)));
131 } else if (!WIFEXITED(status)) {
132 syslog(LOG_ERR,"call pid %ld died due to unknown reason, code %d",
134 } else if (WEXITSTATUS(status)==10) {
136 } else if (WEXITSTATUS(status)>12) {
137 if (WEXITSTATUS(status)>24)
138 syslog(LOG_ERR,"call pid %ld exited with status %d >24",
139 (long)r,WEXITSTATUS(status));
149 static void sighandler_usr1(int x) {
153 static void sighandler_alrm(int x) {
157 static void sighandler_termint(int sig) {
158 syslog(LOG_NOTICE,"terminating due to signal %s",strsignal(sig));
162 static void blocksignals(int how) {
167 sigaddset(&set,SIGCHLD);
168 sigaddset(&set,SIGALRM);
169 sigaddset(&set,SIGTERM);
170 sigaddset(&set,SIGINT);
171 r= sigprocmask(how,&set,0); assert(!r);
174 static void NONRETURNING docheck(int needwanted) {
176 /* This subprocess exits with status 0 if the parent should die,
177 * 1 if it should not, and something else if it fails horribly.
181 struct opening_msg opening_mbuf;
182 struct request_msg request_mbuf;
183 unsigned long endmagic;
184 struct sigaction sig;
185 struct sockaddr_un ssockname;
187 openlog(USERVDCHECK_LOGIDENT,LOG_NDELAY|LOG_PID,USERVD_LOGFACILITY);
189 sigemptyset(&sig.sa_mask);
191 sig.sa_handler= SIG_IGN;
192 if (sigaction(SIGPIPE,&sig,0)) { syslog(LOG_ERR,"ignore sigpipe"); exit(1); }
194 sig.sa_handler= SIG_DFL;
195 if (sigaction(SIGALRM,&sig,0)) { syslog(LOG_ERR,"default sigalarm"); exit(1); }
197 sfd= socket(AF_UNIX,SOCK_STREAM,0);
198 if (!sfd) { syslog(LOG_ERR,"ignore sigpipe"); exit(1); }
200 assert(sizeof(ssockname.sun_path) > sizeof(RENDEZVOUS));
201 ssockname.sun_family= AF_UNIX;
202 strcpy(ssockname.sun_path,RENDEZVOUS);
204 r= connect(sfd,(struct sockaddr*)&ssockname,sizeof(ssockname));
206 if (errno == ECONNREFUSED || errno == ENOENT) {
208 syslog(LOG_WARNING,"real uservd daemon is not running: %m");
211 syslog(LOG_ERR,"unable to connect to uservd daemon: %m"); exit(1);
214 alarm(USERVD_MYSELF_TIMEOUT);
215 remain= sizeof(opening_mbuf); p= (unsigned char*)&opening_mbuf;
217 r= read(sfd,p,remain);
218 if (r<0) { syslog(LOG_ERR,"read from server: %m"); exit(1); }
219 if (r==0) { syslog(LOG_ERR,"unexpected EOF from server"); exit(1); }
222 if (opening_mbuf.magic != OPENING_MAGIC) {
223 syslog(LOG_WARNING,"magic number mismatch");
226 if (memcmp(opening_mbuf.protocolchecksumversion,protocolchecksumversion,PCSUMSIZE)) {
227 syslog(LOG_WARNING,"protocol checksum mismatch");
230 if (opening_mbuf.overlordpid != overlordpid) {
231 syslog(LOG_WARNING,"overlord pid mismatch");
234 memset(&request_mbuf,0,sizeof(request_mbuf));
235 request_mbuf.magic= REQUEST_MAGIC;
236 request_mbuf.clientpid= -1;
237 request_mbuf.serviceuserlen= 0;
238 request_mbuf.servicelen= 0;
239 request_mbuf.loginnamelen= 0;
240 request_mbuf.spoofed= 0;
241 request_mbuf.cwdlen= 0;
242 request_mbuf.overridelen= -1;
243 request_mbuf.callinguid= -1;
244 request_mbuf.ngids= 0;
245 request_mbuf.nreadfds= 0;
246 request_mbuf.nwritefds= 0;
247 request_mbuf.nargs= 0;
248 request_mbuf.nvars= 0;
249 r= write(sfd,&request_mbuf,sizeof(request_mbuf));
250 if (r==sizeof(request_mbuf)) {
251 endmagic= REQUEST_END_MAGIC;
252 r= write(sfd,&endmagic,sizeof(endmagic));
255 syslog(LOG_NOTICE,"uservd[%ld] is running",(long)overlordpid);
260 static void NONRETURNING startupsyscallerr(const char *what) {
262 "uservd: system call failed during startup:\n"
264 what,strerror(errno));
268 int main(int argc, char *const *argv) {
269 int mfd, sfd, nfd, e, r, becomedaemon;
271 struct sigaction sigact;
272 struct sockaddr_un ssockname, csockname;
273 pid_t child, parentpid, sid;
276 abort(); /* Do not disable assertions in this security-critical code ! */
281 if (argv[1] && !strcmp(argv[1],"-daemon")) {
285 if (argc>1) { fputs("usage: uservd [-daemon]\n",stderr); exit(3); }
287 openlog(USERVD_LOGIDENT,LOG_NDELAY|LOG_PID,USERVD_LOGFACILITY);
289 if (chdir(VARDIR)) startupsyscallerr("cannot change to " VARDIR);
292 overlordpid= parentpid= getpid();
293 if (parentpid==-1) startupsyscallerr("cannot getpid");
295 mfd= socket(AF_UNIX,SOCK_STREAM,0);
296 if (mfd<0) startupsyscallerr("cannot create master socket");
298 assert(sizeof(ssockname.sun_path) > sizeof(RENDEZVOUS));
299 ssockname.sun_family= AF_UNIX;
300 strcpy(ssockname.sun_path,RENDEZVOUS);
302 r= bind(mfd,(struct sockaddr*)&ssockname,sizeof(ssockname));
303 if (r) startupsyscallerr("cannot bind master socket");
304 if (listen(mfd,5)) startupsyscallerr("cannot listen on master socket");
306 sigemptyset(&sigact.sa_mask);
307 sigaddset(&sigact.sa_mask,SIGCHLD);
308 sigaddset(&sigact.sa_mask,SIGALRM);
309 sigact.sa_flags= SA_NOCLDSTOP;
311 sigact.sa_handler= sighandler_chld;
312 if (sigaction(SIGCHLD,&sigact,0)) startupsyscallerr("cannot setup sigchld handler");
314 sigact.sa_handler= sighandler_alrm;
315 if (sigaction(SIGALRM,&sigact,0)) startupsyscallerr("cannot setup sigalrm handler");
318 sigact.sa_handler= sighandler_usr1;
319 if (sigaction(SIGUSR1,&sigact,0)) startupsyscallerr("cannot setup sigusr1 handler");
321 detachpid= fork(); if (detachpid==-1) startupsyscallerr("cannot fork to detach");
324 fputs("uservd: pause unexpectedly returned during detach\n",stderr);
327 sigact.sa_handler= SIG_DFL;
328 if (sigaction(SIGUSR1,&sigact,0)) startupsyscallerr("cannot restore sigusr1");
331 sigact.sa_handler= sighandler_termint;
332 if (sigaction(SIGTERM,&sigact,0)) startupsyscallerr("cannot setup sigterm handler");
333 if (sigaction(SIGINT,&sigact,0)) startupsyscallerr("cannot setup sigint handler");
336 nfd= open("/dev/null",O_RDWR);
337 if (nfd<0) startupsyscallerr("cannot open /dev/null");
338 sid= setsid(); if (sid == -1) startupsyscallerr("cannot create new session");
339 overlordpid= getpid();
340 if (overlordpid == -1) startupsyscallerr("getpid after detach");
341 if (dup2(nfd,0)<0 || dup2(nfd,1)<0)
342 startupsyscallerr("cannot dup /dev/null for stdin/out");
343 r= kill(parentpid,SIGUSR1); if (r) startupsyscallerr("send SIGUSR1 to detach");
345 if (r<0) { syslog(LOG_CRIT,"cannot dup /dev/null for stderr: %m"); exit(5); }
349 syslog(LOG_NOTICE,"started");
353 while (checkpid==-1) {
356 if (!checkpid) docheck(needcheck);
358 } else if (errno==EAGAIN) {
359 syslog(LOG_ERR,"fork for check - will wait and retry: %m");
360 alarm(USERVD_CHECKFORK_RETRY);
362 } else if (errno!=EINTR) {
363 syslog(LOG_CRIT,"fork for check: %m"); exit(5);
368 csocklen= sizeof(csockname);
369 blocksignals(SIG_UNBLOCK);
370 sfd= accept(mfd,(struct sockaddr*)&csockname,&csocklen);
372 blocksignals(SIG_BLOCK);
375 if (errno == EINTR) continue;
376 if (errno == ENOMEM || errno == EPROTO || errno == EAGAIN) {
377 syslog(LOG_ERR,"unable to accept connection: %m");
380 syslog(LOG_CRIT,"unable to accept new connections: %m");
384 child= nondebug_fork();
385 if (child == (pid_t)-1) {
386 syslog(LOG_ERR,"unable to fork server: %m");
393 blocksignals(SIG_UNBLOCK);