3 * daemon code to process one request (is parent of service process)
5 * Copyright (C)1996-1999,2001,2003 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/types.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 reporttermination(int status) {
275 struct progress_msg progress_mbuf;
277 memset(&progress_mbuf,0,sizeof(progress_mbuf));
278 progress_mbuf.magic= PROGRESS_MAGIC;
279 progress_mbuf.type= pt_terminated;
280 progress_mbuf.data.terminated.status= status;
281 xfwrite(&progress_mbuf,sizeof(progress_mbuf),swfile);
285 static void NONRETURNING sighandler_chld(int ignored) {
289 returned= wait3(&status,WNOHANG,0);
290 if (returned==-1) syscallerror("wait for child failed");
291 if (!returned) syscallerror("spurious sigchld");
292 if (returned!=child) syscallerror("spurious child process");
293 child= childtokill= -1;
295 reporttermination(status);
296 syslog(LOG_INFO,"service completed (status %d %d)",(status>>8)&0x0ff,status&0x0ff);
300 /* Functions which are called only during setup, before
301 * the signal asynchronicity starts. They can do anything they like.
304 void ensurefdarray(int fd) {
305 if (fd < fdarrayused) return;
306 if (fd >= fdarraysize) {
307 fdarraysize= ((fd+2)<<1);
308 fdarray= xrealloc(fdarray,sizeof(struct fdstate)*fdarraysize);
310 while (fd >= fdarrayused) {
311 fdarray[fdarrayused].iswrite= -1;
312 fdarray[fdarrayused].realfd= -1;
313 fdarray[fdarrayused].holdfd= -1;
314 fdarray[fdarrayused].wantstate= restfdwantstate;
315 fdarray[fdarrayused].wantrw= restfdwantrw;
320 static void NONRETURNING generalfailure(const char *prefix, int reserveerrno,
321 int errnoval, const char *fmt, va_list al) {
322 char errmsg[MAX_ERRMSG_LEN];
325 strnycpy(errmsg,prefix,sizeof(errmsg));
326 strnytcat(errmsg,": ",sizeof(errmsg));
330 vsnytprintfcat(errmsg,sizeof(errmsg)-reserveerrno,fmt,al);
332 strnytcat(errmsg,": ",sizeof(errmsg));
333 strnytcat(errmsg,strerror(errnoval),sizeof(errmsg));
335 senderrmsgstderr(errmsg);
336 syslog(LOG_INFO,"service failed (%s)",errmsg);
340 static void NONRETURNPRINTFFORMAT(1,2) failure(const char *fmt, ...) {
344 generalfailure(0,0,0,fmt,al);
347 static void NONRETURNPRINTFFORMAT(1,2) syscallfailure(const char *fmt, ...) {
353 generalfailure("system call failed",ERRMSG_RESERVE_ERRNO,e,fmt,al);
356 void senderrmsgstderr(const char *errmsg) {
357 struct progress_msg progress_mbuf;
362 memset(&progress_mbuf,0,sizeof(progress_mbuf));
363 progress_mbuf.magic= PROGRESS_MAGIC;
364 progress_mbuf.type= pt_errmsg;
365 progress_mbuf.data.errmsg.messagelen= l;
366 xfwrite(&progress_mbuf,sizeof(progress_mbuf),swfile);
367 xfwrite(errmsg,l,swfile);
368 ul= PROGRESS_ERRMSG_END_MAGIC;
369 xfwrite(&ul,sizeof(ul),swfile);
373 /* The per-request main program and its subfunctions. */
375 static void setup_comms(int sfd) {
376 static char swbuf[BUFSIZ];
377 static char srbuf[BUFSIZ];
379 struct sigaction sig;
381 ensurelogopen(USERVD_LOGFACILITY);
382 syslog(LOG_DEBUG,"call connected");
384 mypid= getpid(); if (mypid == -1) syscallerror("getpid");
386 sig.sa_handler= SIG_IGN;
387 sigemptyset(&sig.sa_mask);
389 if (sigaction(SIGPIPE,&sig,0)) syscallerror("cannot ignore sigpipe");
391 srfile= fdopen(sfd,"r");
392 if (!srfile) syscallerror("turn socket fd into reading FILE*");
393 if (setvbuf(srfile,srbuf,_IOFBF,sizeof(srbuf)))
394 syscallerror("set buffering on socket reads");
396 swfile= fdopen(sfd,"w");
397 if (!swfile) syscallerror("turn socket fd into writing FILE*");
398 if (setvbuf(swfile,swbuf,_IOFBF,sizeof(swbuf)))
399 syscallerror("set buffering on socket writes");
402 static void send_opening(void) {
403 struct opening_msg opening_mbuf;
405 memset(&opening_mbuf,0,sizeof(opening_mbuf));
406 opening_mbuf.magic= OPENING_MAGIC;
407 memcpy(opening_mbuf.protocolchecksumversion,protocolchecksumversion,PCSUMSIZE);
408 opening_mbuf.overlordpid= overlordpid;
409 opening_mbuf.serverpid= mypid;
410 xfwrite(&opening_mbuf,sizeof(opening_mbuf),swfile);
414 static void receive_request(void) {
418 xfread(&request_mbuf,sizeof(request_mbuf));
419 serviceuser= xfreadsetstring(request_mbuf.serviceuserlen);
420 service= xfreadsetstring(request_mbuf.servicelen);
421 assert(request_mbuf.spoofed==0 || request_mbuf.spoofed==1);
422 loginname= xfreadsetstring(request_mbuf.loginnamelen);
423 cwd= xfreadsetstring(request_mbuf.cwdlen);
424 if (request_mbuf.overridelen >= 0) {
425 assert(request_mbuf.overridelen <= MAX_OVERRIDE_LEN);
426 overridedata= xfreadsetstring(request_mbuf.overridelen);
428 assert(request_mbuf.overridelen == -1);
431 assert(request_mbuf.ngids <= MAX_GIDS);
432 calling_gids= xmalloc(sizeof(gid_t)*request_mbuf.ngids);
433 xfread(calling_gids,sizeof(gid_t)*request_mbuf.ngids);
435 fdarraysize= 4; fdarray= xmalloc(sizeof(struct fdstate)*fdarraysize);
436 fdarrayused= 1; fdarray[0].iswrite= -1;
437 fdarray[0].wantstate= tokv_word_rejectfd;
438 assert(request_mbuf.nreadfds+request_mbuf.nwritefds <= MAX_ALLOW_FD+1);
439 for (i=0; i<request_mbuf.nreadfds+request_mbuf.nwritefds; i++) {
440 xfread(&fd,sizeof(int));
441 assert(fd <= MAX_ALLOW_FD);
443 assert(fdarray[fd].iswrite == -1);
444 fdarray[fd].iswrite= (i>=request_mbuf.nreadfds);
446 /* fdarray[].iswrite now set; rest is still blank
447 * (ie want reject read, no realfd holdfd). */
449 assert(request_mbuf.nargs <= MAX_ARGSDEFVAR);
450 argarray= xmalloc(sizeof(char*)*(request_mbuf.nargs));
451 for (i=0; i<request_mbuf.nargs; i++) argarray[i]= xfreadstring();
452 assert(request_mbuf.nvars <= MAX_ARGSDEFVAR);
453 defvararray= xmalloc(sizeof(struct keyvaluepair)*request_mbuf.nvars);
454 for (i=0; i<request_mbuf.nvars; i++) {
455 defvararray[i].key= xfreadstring();
456 assert(defvararray[i].key[0]);
457 defvararray[i].value= xfreadstring();
459 xfread(&ul,sizeof(ul));
460 assert(ul == REQUEST_END_MAGIC);
463 static void establish_pipes(void) {
465 char pipepathbuf[PIPEMAXLEN+2];
467 for (fd=0; fd<fdarrayused; fd++) {
468 if (fdarray[fd].iswrite == -1) continue;
469 pipepathbuf[sizeof(pipepathbuf)-2]= 0;
470 snyprintf(pipepathbuf,sizeof(pipepathbuf),PIPEFORMAT,
471 (unsigned long)request_mbuf.clientpid,(unsigned long)mypid,fd);
472 assert(!pipepathbuf[sizeof(pipepathbuf)-2]);
473 tempfd= open(pipepathbuf,O_RDWR);
474 if (tempfd<0) syscallerror("prelim open pipe");
475 if (fdarray[fd].iswrite) {
476 fdarray[fd].holdfd= -1;
477 fdarray[fd].realfd= open(pipepathbuf, O_WRONLY);
479 fdarray[fd].holdfd= open(pipepathbuf, O_WRONLY);
480 if (fdarray[fd].holdfd<0) syscallerror("hold open pipe");
481 fdarray[fd].realfd= open(pipepathbuf, O_RDONLY);
483 if (fdarray[fd].realfd<0) syscallerror("real open pipe");
484 if (unlink(pipepathbuf)) syscallerror("unlink pipe");
485 if (close(tempfd)) syscallerror("close prelim fd onto pipe");
487 /* Now fdarray[].realfd is pipe end for service in case service
488 * wants it. If it's an input pipe, then .holdfd is the other
489 * (writing) end of the pipe - we keep it around so that the service
490 * doesn't get an apparently clean EOF if the caller disappears (eg
491 * due to a file read error) or the like (ie so that on disconnect
492 * we can guarantee to send the service SIGHUP before it gets EOF on
493 * the input fd). Otherwise, .holdfd=-1.
497 static void groupnames(int ngids, gid_t *gids, const char ***names_r) {
502 names= xmalloc(sizeof(char*)*ngids);
503 for (i=0; i<ngids; i++) {
504 gr= getgrgid(gids[i]);
505 if (!gr) miscerror("get group entry");
506 names[i]= xstrsave(gr->gr_name);
511 static void lookup_uidsgids(void) {
514 pw= getpwnam(loginname);
515 if (!pw) miscerror("look up calling user");
516 assert(!strcmp(pw->pw_name,loginname));
517 callinguser_shell= xstrsave(pw->pw_shell);
519 pw= getpwnam(serviceuser);
520 if (!pw) miscerror("look up service user");
521 assert(!strcmp(pw->pw_name,serviceuser));
522 serviceuser_dir= xstrsave(nondebug_serviceuserdir(pw->pw_dir));
523 serviceuser_shell= xstrsave(pw->pw_shell);
524 serviceuser_uid= pw->pw_uid;
526 if (setregid(pw->pw_gid,pw->pw_gid)) syscallerror("setregid 1");
527 if (initgroups(pw->pw_name,pw->pw_gid)) syscallerror("initgroups");
528 if (setreuid(pw->pw_uid,pw->pw_uid)) syscallerror("setreuid 1");
529 if (setreuid(pw->pw_uid,pw->pw_uid)) syscallerror("setreuid 2");
531 if (!setreuid(pw->pw_uid,0)) miscerror("setreuid 3 unexpectedly succeeded");
532 if (errno != EPERM) syscallerror("setreuid 3 failed in unexpected way");
534 if (setregid(pw->pw_gid,pw->pw_gid)) syscallerror("setregid 2");
536 service_ngids= getgroups(0,0); if (service_ngids == -1) syscallerror("getgroups(0,0)");
537 if (service_ngids > MAX_GIDS) miscerror("service user is in far too many groups");
538 service_gids= xmalloc(sizeof(gid_t)*(service_ngids+1));
539 service_gids[0]= pw->pw_gid;
540 if (getgroups(service_ngids,service_gids+1) != service_ngids)
541 syscallerror("getgroups(size,list)");
543 groupnames(request_mbuf.ngids,calling_gids,&calling_groups);
544 groupnames(service_ngids,service_gids,&service_groups);
547 static void findinpath(char *program) {
548 char *part, *exectry;
549 const char *string, *delim, *nextstring;
553 if (strchr(program,'/')) {
554 r= stat(program,&stab);
555 if (r) syscallfailure("failed check for program (containing slash) `%s'",program);
558 string= getenv("PATH");
559 if (!string) string= defaultpath();
561 delim= strchr(string,':');
563 if (delim-string > MAX_GENERAL_STRING)
564 failure("execute-from-path, but PATH component too long");
565 partsize= delim-string;
568 partsize= strlen(string);
571 part= xstrsubsave(string,partsize);
572 exectry= part[0] ? xstrcat3save(part,"/",program) : xstrsave(program);
574 r= stat(exectry,&stab);
575 if (!r) { execpath= exectry; break; }
579 if (!execpath) failure("program `%s' not found on default PATH",program);
583 static void check_find_executable(void) {
588 case tokv_word_reject:
589 failure("request rejected");
590 case tokv_word_execute:
591 findinpath(execpath);
593 case tokv_word_executefromdirectory:
594 r= stat(execpath,&stab);
595 if (r) syscallfailure("checking for executable in directory, `%s'",execpath);
597 case tokv_word_executebuiltin:
599 case tokv_word_executefrompath:
607 static void makenonexistentfd(int fd) {
608 if (fdarray[fd].realfd == -1) {
609 assert(fdarray[fd].holdfd == -1);
611 if (close(fdarray[fd].realfd))
612 syscallfailure("close unwanted file descriptor %d",fd);
613 fdarray[fd].realfd= -1;
615 if (fdarray[fd].holdfd != -1) {
616 if (close(fdarray[fd].holdfd))
617 syscallfailure("close unwanted hold descriptor for %d",fd);
618 fdarray[fd].holdfd= -1;
623 static void makenullfd(int fd) {
624 fdarray[fd].realfd= open("/dev/null",
625 fdarray[fd].wantrw == tokv_word_read ? O_RDONLY :
626 fdarray[fd].wantrw == tokv_word_write ? O_WRONLY :
628 if (fdarray[fd].realfd<0)
629 syscallfailure("cannot open /dev/null for null or allowed, unprovided fd");
632 static void check_fds(void) {
635 assert(fdarrayused>=2);
636 if (!(fdarray[2].wantstate == tokv_word_requirefd ||
637 fdarray[2].wantstate == tokv_word_allowfd) ||
638 fdarray[2].wantrw != tokv_word_write)
639 failure("must have stderr (fd 2), but file descriptor setup in "
640 "configuration does not have it or not for writing");
642 for (fd=0; fd<fdarrayused; fd++) {
643 switch (fdarray[fd].wantstate) {
644 case tokv_word_rejectfd:
645 if (fdarray[fd].realfd != -1)
646 failure("file descriptor %d provided but rejected",fd);
648 case tokv_word_ignorefd:
649 makenonexistentfd(fd);
651 case tokv_word_nullfd:
652 makenonexistentfd(fd);
655 case tokv_word_requirefd:
656 if (fdarray[fd].realfd == -1)
657 failure("file descriptor %d required but not provided",fd);
659 case tokv_word_allowfd:
660 if (fdarray[fd].realfd == -1) {
661 assert(fdarray[fd].holdfd == -1);
664 if (fdarray[fd].iswrite) {
665 if (fdarray[fd].wantrw == tokv_word_read)
666 failure("file descriptor %d provided write, wanted read",fd);
668 if (fdarray[fd].wantrw == tokv_word_write)
669 failure("file descriptor %d provided read, wanted write",fd);
674 /* Now fdarray[].realfd is exactly what service wants: pipe end or
675 * /dev/null or -1. If .realfd is not -1 then .holdfd may be the fd
676 * for the writing end of the corresponding pipe.
680 static void send_progress_ok(void) {
681 struct progress_msg progress_mbuf;
683 memset(&progress_mbuf,0,sizeof(progress_mbuf));
684 progress_mbuf.magic= PROGRESS_MAGIC;
685 progress_mbuf.type= pt_ok;
686 xfwrite(&progress_mbuf,sizeof(progress_mbuf),swfile);
690 static void fork_service_synch(void) {
692 struct sigaction sig;
693 int r, synchsocket[2];
696 r= socketpair(AF_UNIX,SOCK_STREAM,0,synchsocket);
697 if (r) syscallerror("cannot create socket for synch");
699 /* Danger here. Firstly, we start handling signals asynchronously.
700 * Secondly after we fork the service we want it to put
701 * itself in a separate process group so that we can kill it and all
702 * its children - but, we mustn't kill the whole pgrp before it has
703 * done that (or we kill ourselves) and it mustn't fork until it
704 * knows that we are going to kill it the right way ...
706 sig.sa_handler= sighandler_chld;
707 sigemptyset(&sig.sa_mask);
708 sigaddset(&sig.sa_mask,SIGCHLD);
710 if (sigaction(SIGCHLD,&sig,0)) syscallerror("cannot set sigchld handler");
713 if (newchild == -1) syscallerror("cannot fork to invoke service");
714 if (!newchild) execservice(synchsocket,fileno(swfile));
715 childtokill= child= newchild;
717 if (close(synchsocket[1])) syscallerror("cannot close other end of synch socket");
719 r= synchread(synchsocket[0],'y');
720 if (r) syscallerror("read synch byte from child");
725 r= write(synchsocket[0],&synchmsg,1);
726 if (r!=1) syscallerror("write synch byte to child");
728 if (close(synchsocket[0])) syscallerror("cannot close my end of synch socket");
731 void servicerequest(int sfd) {
732 struct event_msg event_mbuf;
738 if (request_mbuf.clientpid == (pid_t)-1) _exit(2);
741 debug_dumprequest(mypid);
742 syslog(LOG_INFO,"%s %s -> %s %c %s",
743 request_mbuf.spoofed ? "spoof" : "user",
744 loginname, serviceuser, overridedata?'!':':', service);
747 r= parse_string(TOPLEVEL_OVERRIDDEN_CONFIGURATION,
748 "<builtin toplevel override configuration>",1);
750 r= parse_string(TOPLEVEL_CONFIGURATION,
751 "<builtin toplevel configuration>",1);
753 ensurelogopen(USERVD_LOGFACILITY);
754 if (r == tokv_error) failure("error encountered while parsing configuration");
755 assert(r == tokv_quit);
757 debug_dumpexecsettings();
759 check_find_executable();
763 getevent(&event_mbuf);
764 assert(event_mbuf.type == et_confirm);
766 if (execbuiltin == bisexec_shutdown && !serviceuser_uid) {
767 /* The check for the uid is just so we can give a nice
768 * error message (in the actual code for bisexec_shutdown).
769 * If this is spoofed somehow then the unlink() will simply fail.
771 r= unlink(RENDEZVOUSPATH);
772 if (r) syscallfailure("remove rendezvous socket %s",RENDEZVOUSPATH);
773 syslog(LOG_NOTICE,"arranging for termination, due to client request");
774 reporttermination(0);
778 fork_service_synch();
780 getevent(&event_mbuf);