3 * daemon code to process one request (is parent of service process)
5 * Copyright (C)1996-1999 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.
23 * We do some horrible asynchronous stuff with signals.
25 * The following objects &c. are used in signal handlers and so
26 * must be protected by calls to blocksignals if they are used in
28 * the syslog() family of calls, and the associated
29 * syslogopenfacility variable
30 * swfile (stdio stream)
32 * The following objects are used in the main program unprotected
33 * and so must not be used in signal handlers:
36 * child and childtokill are used for communication between the
37 * main thread and the signal handlers; none of the signal handlers
38 * return so errno is OK too.
56 #include <sys/resource.h>
57 #include <sys/fcntl.h>
59 #include <sys/socket.h>
69 /* NB: defaults for the execution state are not set here, but in
70 * the RESET_CONFIGURATION #define in daemon.h. */
71 struct request_msg request_mbuf;
72 struct keyvaluepair *defvararray;
73 struct fdstate *fdarray;
74 int fdarraysize, fdarrayused;
75 int restfdwantstate= tokv_word_rejectfd, restfdwantrw;
78 char *serviceuser, *service, *loginname, *cwd;
79 char *overridedata, *userrcfile;
80 char *serviceuser_dir, *serviceuser_shell, *callinguser_shell;
81 gid_t *calling_gids, *service_gids;
82 uid_t serviceuser_uid=-1;
83 const char **calling_groups, **service_groups;
84 char *execpath, **execargs;
86 int setenvironment, suppressargs, disconnecthup;
87 builtinserviceexec_fnt *execbuiltin;
88 int syslogopenfacility=-1;
90 static FILE *swfile, *srfile;
91 static pid_t child=-1, childtokill=-1;
94 /* Function shared with servexec.c: */
96 int synchread(int fd, int ch) {
101 r= read(fd,&synchmsg,1);
103 if (r==0) { errno= ECONNRESET; return -1; }
105 if (errno!=EINTR) return -1;
107 assert(synchmsg==ch);
111 const char *defaultpath(void) {
112 return serviceuser_uid ? DEFAULTPATH_USER : DEFAULTPATH_ROOT;
115 /* General-purpose functions; these do nothing special about signals */
117 static void blocksignals(void) {
122 sigaddset(&set,SIGCHLD);
123 sigaddset(&set,SIGPIPE);
124 r= sigprocmask(SIG_BLOCK,&set,0); assert(!r);
127 static void xfwriteerror(void) {
128 if (errno != EPIPE) syscallerror("writing to client");
130 ensurelogopen(USERVD_LOGFACILITY);
131 syslog(LOG_INFO,"client went away (broken pipe)");
135 static void xfwrite(const void *p, size_t sz, FILE *file) {
137 nr= fwrite(p,1,sz,file);
138 if (nr != sz) xfwriteerror();
141 static void xfflush(FILE *file) {
142 if (fflush(file)) xfwriteerror();
145 /* Functions which may be called only from the main thread. These may
146 * use main-thread objects and must block signals before using signal
150 static void xfread(void *p, size_t sz) {
152 nr= working_fread(p,sz,srfile); if (nr == sz) return;
153 if (ferror(srfile)) syscallerror("reading from client");
155 assert(feof(srfile));
156 syslog(LOG_INFO,"client went away (unexpected EOF)");
161 static char *xfreadsetstring(int l) {
163 assert(l<=MAX_GENERAL_STRING);
165 xfread(s,sizeof(*s)*l);
170 static char *xfreadstring(void) {
172 xfread(&l,sizeof(l));
173 return xfreadsetstring(l);
176 static void getevent(struct event_msg *event_r) {
180 xfread(event_r,sizeof(struct event_msg));
181 switch (event_r->type) {
183 fd= event_r->data.closereadfd.fd;
184 if (fd >= fdarrayused) {
186 syslog(LOG_ERR,"client sent bad file descriptor %d to close (max %d)",
190 if (fdarray[fd].holdfd!=-1) {
191 if (close(fdarray[fd].holdfd)) syscallerror("cannot close holding fd");
192 fdarray[fd].holdfd= -1;
197 syslog(LOG_INFO,"client disconnected");
205 /* Functions which may be called either from signal handlers or from
206 * the main thread. They block signals in case they are on the main
207 * thread, and may only use signal handler objects. None of them
208 * return. If they did they'd have to restore the signal mask.
211 void miscerror(const char *what) {
213 syslog(LOG_ERR,"failure: %s",what);
217 void syscallerror(const char *what) {
222 syslog(LOG_ERR,"system call failure: %s: %s",what,strerror(e));
226 /* Functions which may be called from signal handlers. These
227 * may use signal-handler objects. The main program may only
228 * call them with signals blocked, and they may not use any
229 * main-thread objects.
232 void ensurelogopen(int wantfacility) {
233 if (syslogopenfacility==wantfacility) return;
234 if (syslogopenfacility!=-1) closelog();
235 openlog(USERVD_LOGIDENT,LOG_NDELAY|LOG_PID,wantfacility);
236 syslogopenfacility= wantfacility;
239 void NONRETURNING disconnect(int exitstatus) {
240 /* This function can sometimes indirectly call itself (eg,
241 * xfwrite, syscallerror can cause it to be called). So, all
242 * the global variables indicating need for action are reset
243 * before the action is taken so that if it fails it isn't
246 struct progress_msg progress_mbuf;
251 if (childtokill!=-1 && disconnecthup) {
252 orgtokill= childtokill;
255 r= kill(-orgtokill,SIGHUP);
256 if (r && errno!=EPERM && errno!=ESRCH)
257 syscallerror("sending SIGHUP to service process group");
264 memset(&progress_mbuf,0,sizeof(progress_mbuf));
265 progress_mbuf.magic= PROGRESS_MAGIC;
266 progress_mbuf.type= pt_failed;
267 xfwrite(&progress_mbuf,sizeof(progress_mbuf),swfilereal);
274 static void NONRETURNING sighandler_chld(int ignored) {
275 struct progress_msg progress_mbuf;
279 returned= wait3(&status,WNOHANG,0);
280 if (returned==-1) syscallerror("wait for child failed");
281 if (!returned) syscallerror("spurious sigchld");
282 if (returned!=child) syscallerror("spurious child process");
283 child= childtokill= -1;
285 memset(&progress_mbuf,0,sizeof(progress_mbuf));
286 progress_mbuf.magic= PROGRESS_MAGIC;
287 progress_mbuf.type= pt_terminated;
288 progress_mbuf.data.terminated.status= status;
289 xfwrite(&progress_mbuf,sizeof(progress_mbuf),swfile);
292 syslog(LOG_INFO,"service completed (status %d %d)",(status>>8)&0x0ff,status&0x0ff);
296 /* Functions which are called only during setup, before
297 * the signal asynchronicity starts. They can do anything they like.
300 void ensurefdarray(int fd) {
301 if (fd < fdarrayused) return;
302 if (fd >= fdarraysize) {
303 fdarraysize= ((fd+2)<<1);
304 fdarray= xrealloc(fdarray,sizeof(struct fdstate)*fdarraysize);
306 while (fd >= fdarrayused) {
307 fdarray[fdarrayused].iswrite= -1;
308 fdarray[fdarrayused].realfd= -1;
309 fdarray[fdarrayused].holdfd= -1;
310 fdarray[fdarrayused].wantstate= restfdwantstate;
311 fdarray[fdarrayused].wantrw= restfdwantrw;
316 static void NONRETURNING generalfailure(const char *prefix, int reserveerrno,
317 int errnoval, const char *fmt, va_list al) {
318 char errmsg[MAX_ERRMSG_LEN];
321 strnycpy(errmsg,prefix,sizeof(errmsg));
322 strnytcat(errmsg,": ",sizeof(errmsg));
326 vsnytprintfcat(errmsg,sizeof(errmsg)-reserveerrno,fmt,al);
328 strnytcat(errmsg,": ",sizeof(errmsg));
329 strnytcat(errmsg,strerror(errnoval),sizeof(errmsg));
331 senderrmsgstderr(errmsg);
332 syslog(LOG_INFO,"service failed (%s)",errmsg);
336 static void NONRETURNPRINTFFORMAT(1,2) failure(const char *fmt, ...) {
340 generalfailure(0,0,0,fmt,al);
343 static void NONRETURNPRINTFFORMAT(1,2) syscallfailure(const char *fmt, ...) {
349 generalfailure("system call failed",ERRMSG_RESERVE_ERRNO,e,fmt,al);
352 void senderrmsgstderr(const char *errmsg) {
353 struct progress_msg progress_mbuf;
358 memset(&progress_mbuf,0,sizeof(progress_mbuf));
359 progress_mbuf.magic= PROGRESS_MAGIC;
360 progress_mbuf.type= pt_errmsg;
361 progress_mbuf.data.errmsg.messagelen= l;
362 xfwrite(&progress_mbuf,sizeof(progress_mbuf),swfile);
363 xfwrite(errmsg,l,swfile);
364 ul= PROGRESS_ERRMSG_END_MAGIC;
365 xfwrite(&ul,sizeof(ul),swfile);
369 /* The per-request main program and its subfunctions. */
371 static void setup_comms(int sfd) {
372 static char swbuf[BUFSIZ];
373 static char srbuf[BUFSIZ];
375 struct sigaction sig;
377 ensurelogopen(USERVD_LOGFACILITY);
378 syslog(LOG_DEBUG,"call connected");
380 mypid= getpid(); if (mypid == -1) syscallerror("getpid");
382 sig.sa_handler= SIG_IGN;
383 sigemptyset(&sig.sa_mask);
385 if (sigaction(SIGPIPE,&sig,0)) syscallerror("cannot ignore sigpipe");
387 srfile= fdopen(sfd,"r");
388 if (!srfile) syscallerror("turn socket fd into reading FILE*");
389 if (setvbuf(srfile,srbuf,_IOFBF,sizeof(srbuf)))
390 syscallerror("set buffering on socket reads");
392 swfile= fdopen(sfd,"w");
393 if (!swfile) syscallerror("turn socket fd into writing FILE*");
394 if (setvbuf(swfile,swbuf,_IOFBF,sizeof(swbuf)))
395 syscallerror("set buffering on socket writes");
398 static void send_opening(void) {
399 struct opening_msg opening_mbuf;
401 memset(&opening_mbuf,0,sizeof(opening_mbuf));
402 opening_mbuf.magic= OPENING_MAGIC;
403 memcpy(opening_mbuf.protocolchecksumversion,protocolchecksumversion,PCSUMSIZE);
404 opening_mbuf.overlordpid= overlordpid;
405 opening_mbuf.serverpid= mypid;
406 xfwrite(&opening_mbuf,sizeof(opening_mbuf),swfile);
410 static void receive_request(void) {
414 xfread(&request_mbuf,sizeof(request_mbuf));
415 serviceuser= xfreadsetstring(request_mbuf.serviceuserlen);
416 service= xfreadsetstring(request_mbuf.servicelen);
417 assert(request_mbuf.spoofed==0 || request_mbuf.spoofed==1);
418 loginname= xfreadsetstring(request_mbuf.loginnamelen);
419 cwd= xfreadsetstring(request_mbuf.cwdlen);
420 if (request_mbuf.overridelen >= 0) {
421 assert(request_mbuf.overridelen <= MAX_OVERRIDE_LEN);
422 overridedata= xfreadsetstring(request_mbuf.overridelen);
424 assert(request_mbuf.overridelen == -1);
427 assert(request_mbuf.ngids <= MAX_GIDS);
428 calling_gids= xmalloc(sizeof(gid_t)*request_mbuf.ngids);
429 xfread(calling_gids,sizeof(gid_t)*request_mbuf.ngids);
431 fdarraysize= 4; fdarray= xmalloc(sizeof(struct fdstate)*fdarraysize);
432 fdarrayused= 1; fdarray[0].iswrite= -1;
433 fdarray[0].wantstate= tokv_word_rejectfd;
434 assert(request_mbuf.nreadfds+request_mbuf.nwritefds <= MAX_ALLOW_FD+1);
435 for (i=0; i<request_mbuf.nreadfds+request_mbuf.nwritefds; i++) {
436 xfread(&fd,sizeof(int));
437 assert(fd <= MAX_ALLOW_FD);
439 assert(fdarray[fd].iswrite == -1);
440 fdarray[fd].iswrite= (i>=request_mbuf.nreadfds);
443 assert(request_mbuf.nargs <= MAX_ARGSDEFVAR);
444 argarray= xmalloc(sizeof(char*)*(request_mbuf.nargs));
445 for (i=0; i<request_mbuf.nargs; i++) argarray[i]= xfreadstring();
446 assert(request_mbuf.nvars <= MAX_ARGSDEFVAR);
447 defvararray= xmalloc(sizeof(struct keyvaluepair)*request_mbuf.nvars);
448 for (i=0; i<request_mbuf.nvars; i++) {
449 defvararray[i].key= xfreadstring();
450 assert(defvararray[i].key[0]);
451 defvararray[i].value= xfreadstring();
453 xfread(&ul,sizeof(ul));
454 assert(ul == REQUEST_END_MAGIC);
457 static void establish_pipes(void) {
459 char pipepathbuf[PIPEMAXLEN+2];
461 for (fd=0; fd<fdarrayused; fd++) {
462 if (fdarray[fd].iswrite == -1) continue;
463 pipepathbuf[sizeof(pipepathbuf)-2]= 0;
464 snyprintf(pipepathbuf,sizeof(pipepathbuf),PIPEFORMAT,
465 (unsigned long)request_mbuf.clientpid,(unsigned long)mypid,fd);
466 assert(!pipepathbuf[sizeof(pipepathbuf)-2]);
467 tempfd= open(pipepathbuf,O_RDWR);
468 if (tempfd<0) syscallerror("prelim open pipe");
469 if (fdarray[fd].iswrite) {
470 fdarray[fd].holdfd= -1;
471 fdarray[fd].realfd= open(pipepathbuf, O_WRONLY);
473 fdarray[fd].holdfd= open(pipepathbuf, O_WRONLY);
474 if (fdarray[fd].holdfd<0) syscallerror("hold open pipe");
475 fdarray[fd].realfd= open(pipepathbuf, O_RDONLY);
477 if (fdarray[fd].realfd<0) syscallerror("real open pipe");
478 if (unlink(pipepathbuf)) syscallerror("unlink pipe");
479 if (close(tempfd)) syscallerror("close prelim fd onto pipe");
483 static void groupnames(int ngids, gid_t *gids, const char ***names_r) {
488 names= xmalloc(sizeof(char*)*ngids);
489 for (i=0; i<ngids; i++) {
490 gr= getgrgid(gids[i]);
491 if (!gr) miscerror("get group entry");
492 names[i]= xstrsave(gr->gr_name);
497 static void lookup_uidsgids(void) {
500 pw= getpwnam(loginname);
501 if (!pw) miscerror("look up calling user");
502 assert(!strcmp(pw->pw_name,loginname));
503 callinguser_shell= xstrsave(pw->pw_shell);
505 pw= getpwnam(serviceuser);
506 if (!pw) miscerror("look up service user");
507 assert(!strcmp(pw->pw_name,serviceuser));
508 serviceuser_dir= xstrsave(nondebug_serviceuserdir(pw->pw_dir));
509 serviceuser_shell= xstrsave(pw->pw_shell);
510 serviceuser_uid= pw->pw_uid;
512 if (setregid(pw->pw_gid,pw->pw_gid)) syscallerror("setregid 1");
513 if (initgroups(pw->pw_name,pw->pw_gid)) syscallerror("initgroups");
514 if (setreuid(pw->pw_uid,pw->pw_uid)) syscallerror("setreuid 1");
515 if (setreuid(pw->pw_uid,pw->pw_uid)) syscallerror("setreuid 2");
517 if (!setreuid(pw->pw_uid,0)) miscerror("setreuid 3 unexpectedly succeeded");
518 if (errno != EPERM) syscallerror("setreuid 3 failed in unexpected way");
520 if (setregid(pw->pw_gid,pw->pw_gid)) syscallerror("setregid 2");
522 service_ngids= getgroups(0,0); if (service_ngids == -1) syscallerror("getgroups(0,0)");
523 if (service_ngids > MAX_GIDS) miscerror("service user is in far too many groups");
524 service_gids= xmalloc(sizeof(gid_t)*(service_ngids+1));
525 service_gids[0]= pw->pw_gid;
526 if (getgroups(service_ngids,service_gids+1) != service_ngids)
527 syscallerror("getgroups(size,list)");
529 groupnames(request_mbuf.ngids,calling_gids,&calling_groups);
530 groupnames(service_ngids,service_gids,&service_groups);
533 static void findinpath(char *program) {
534 char *part, *exectry;
535 const char *string, *delim, *nextstring;
539 if (strchr(program,'/')) {
540 r= stat(program,&stab);
541 if (r) syscallfailure("failed check for program (containing slash) `%s'",program);
544 string= getenv("PATH");
545 if (!string) string= defaultpath();
547 delim= strchr(string,':');
549 if (delim-string > MAX_GENERAL_STRING)
550 failure("execute-from-path, but PATH component too long");
551 partsize= delim-string;
554 partsize= strlen(string);
557 part= xstrsubsave(string,partsize);
558 exectry= part[0] ? xstrcat3save(part,"/",program) : xstrsave(program);
560 r= stat(exectry,&stab);
561 if (!r) { execpath= exectry; break; }
565 if (!execpath) failure("program `%s' not found on default PATH",program);
569 static void check_find_executable(void) {
574 case tokv_word_reject:
575 failure("request rejected");
576 case tokv_word_execute:
577 findinpath(execpath);
579 case tokv_word_executefromdirectory:
580 r= stat(execpath,&stab);
581 if (r) syscallfailure("checking for executable in directory, `%s'",execpath);
583 case tokv_word_executebuiltin:
585 case tokv_word_executefrompath:
593 static void makenonexistentfd(int fd) {
594 if (fdarray[fd].realfd == -1) {
595 assert(fdarray[fd].holdfd == -1);
597 if (close(fdarray[fd].realfd))
598 syscallfailure("close unwanted file descriptor %d",fd);
599 fdarray[fd].realfd= -1;
601 if (fdarray[fd].holdfd != -1) {
602 if (close(fdarray[fd].holdfd))
603 syscallfailure("close unwanted hold descriptor for %d",fd);
604 fdarray[fd].holdfd= -1;
609 static void makenullfd(int fd) {
610 fdarray[fd].realfd= open("/dev/null",
611 fdarray[fd].wantrw == tokv_word_read ? O_RDONLY :
612 fdarray[fd].wantrw == tokv_word_write ? O_WRONLY :
614 if (fdarray[fd].realfd<0)
615 syscallfailure("cannot open /dev/null for null or allowed, unprovided fd");
618 static void check_fds(void) {
621 assert(fdarrayused>=2);
622 if (!(fdarray[2].wantstate == tokv_word_requirefd ||
623 fdarray[2].wantstate == tokv_word_allowfd) ||
624 fdarray[2].wantrw != tokv_word_write)
625 failure("must have stderr (fd 2), but file descriptor setup in "
626 "configuration does not have it or not for writing");
628 for (fd=0; fd<fdarrayused; fd++) {
629 switch (fdarray[fd].wantstate) {
630 case tokv_word_rejectfd:
631 if (fdarray[fd].realfd != -1)
632 failure("file descriptor %d provided but rejected",fd);
634 case tokv_word_ignorefd:
635 makenonexistentfd(fd);
637 case tokv_word_nullfd:
638 makenonexistentfd(fd);
641 case tokv_word_requirefd:
642 if (fdarray[fd].realfd == -1)
643 failure("file descriptor %d required but not provided",fd);
644 assert(fdarray[fd].holdfd == -1);
646 case tokv_word_allowfd:
647 if (fdarray[fd].realfd == -1) {
648 assert(fdarray[fd].holdfd == -1);
651 if (fdarray[fd].iswrite) {
652 if (fdarray[fd].wantrw == tokv_word_read)
653 failure("file descriptor %d provided write, wanted read",fd);
655 if (fdarray[fd].wantrw == tokv_word_write)
656 failure("file descriptor %d provided read, wanted write",fd);
663 static void send_progress_ok(void) {
664 struct progress_msg progress_mbuf;
666 memset(&progress_mbuf,0,sizeof(progress_mbuf));
667 progress_mbuf.magic= PROGRESS_MAGIC;
668 progress_mbuf.type= pt_ok;
669 xfwrite(&progress_mbuf,sizeof(progress_mbuf),swfile);
673 static void fork_service_synch(void) {
675 struct sigaction sig;
676 int r, synchsocket[2];
679 r= socketpair(AF_UNIX,SOCK_STREAM,0,synchsocket);
680 if (r) syscallerror("cannot create socket for synch");
682 /* Danger here. Firstly, we start handling signals asynchronously.
683 * Secondly after we fork the service we want it to put
684 * itself in a separate process group so that we can kill it and all
685 * its children - but, we mustn't kill the whole pgrp before it has
686 * done that (or we kill ourselves) and it mustn't fork until it
687 * knows that we are going to kill it the right way ...
689 sig.sa_handler= sighandler_chld;
690 sigemptyset(&sig.sa_mask);
691 sigaddset(&sig.sa_mask,SIGCHLD);
693 if (sigaction(SIGCHLD,&sig,0)) syscallerror("cannot set sigchld handler");
696 if (newchild == -1) syscallerror("cannot fork to invoke service");
697 if (!newchild) execservice(synchsocket,fileno(swfile));
698 childtokill= child= newchild;
700 if (close(synchsocket[1])) syscallerror("cannot close other end of synch socket");
702 r= synchread(synchsocket[0],'y');
703 if (r) syscallerror("read synch byte from child");
708 r= write(synchsocket[0],&synchmsg,1);
709 if (r!=1) syscallerror("write synch byte to child");
711 if (close(synchsocket[0])) syscallerror("cannot close my end of synch socket");
714 void servicerequest(int sfd) {
715 struct event_msg event_mbuf;
721 if (request_mbuf.clientpid == (pid_t)-1) _exit(2);
724 debug_dumprequest(mypid);
725 syslog(LOG_INFO,"%s %s -> %s %c %s",
726 request_mbuf.spoofed ? "spoof" : "user",
727 loginname, serviceuser, overridedata?'!':':', service);
730 r= parse_string(TOPLEVEL_OVERRIDDEN_CONFIGURATION,
731 "<builtin toplevel override configuration>",1);
733 r= parse_string(TOPLEVEL_CONFIGURATION,
734 "<builtin toplevel configuration>",1);
736 ensurelogopen(USERVD_LOGFACILITY);
737 if (r == tokv_error) failure("error encountered while parsing configuration");
738 assert(r == tokv_quit);
740 debug_dumpexecsettings();
742 check_find_executable();
746 getevent(&event_mbuf);
747 assert(event_mbuf.type == et_confirm);
749 fork_service_synch();
751 getevent(&event_mbuf);