usr.sbin/cron/cron/popen.c

   1 /*
   2  * Copyright (c) 1988 The Regents of the University of California.
   3  * All rights reserved.
   4  *
   5  * This code is derived from software written by Ken Arnold and
   6  * published in UNIX Review, Vol. 6, No. 8.
   7  *
   8  * Redistribution and use in source and binary forms are permitted
   9  * provided that the above copyright notice and this paragraph are
  10  * duplicated in all such forms and that any documentation,
  11  * advertising materials, and other materials related to such
  12  * distribution and use acknowledge that the software was developed
  13  * by the University of California, Berkeley.  The name of the
  14  * University may not be used to endorse or promote products derived
  15  * from this software without specific prior written permission.
  16  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
  17  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
  18  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  19  *
  20  * @(#)popen.c  5.7 (Berkeley) 2/14/89
  21  * $FreeBSD: src/usr.sbin/cron/cron/popen.c,v 1.7.2.3 2000/12/11 01:03:31 obrien Exp $
  22  * $DragonFly: src/usr.sbin/cron/cron/popen.c,v 1.4 2004/03/10 18:27:26 dillon Exp $
  23  */
  24
  25 /* this came out of the ftpd sources; it's been modified to avoid the
  26  * globbing stuff since we don't need it.  also execvp instead of execv.
  27  */
  28
  29 #include "cron.h"
  30 #include <sys/signal.h>
  31 #include <fcntl.h>
  32 #include <paths.h>
  33 #if defined(SYSLOG)
  34 # include <syslog.h>
  35 #endif
  36 #if defined(LOGIN_CAP)
  37 # include <login_cap.h>
  38 #endif
  39
  40
  41 #define MAX_ARGS 100
  42 #define WANT_GLOBBING 0
  43
  44 /*
  45  * Special version of popen which avoids call to shell.  This insures noone
  46  * may create a pipe to a hidden program as a side effect of a list or dir
  47  * command.
  48  */
  49 static PID_T *pids;
  50 static int fds;
  51
  52 FILE *
  53 cron_popen(char *program, char *type, entry *e)
  54 {
  55         char *cp;
  56         FILE *iop;
  57         int argc, pdes[2];
  58         PID_T pid;
  59         char *usernm;
  60         char *argv[MAX_ARGS + 1];
  61 # if defined(LOGIN_CAP)
  62         struct passwd   *pwd;
  63         login_cap_t *lc;
  64 # endif
  65 #if WANT_GLOBBING
  66         char **pop, *vv[2];
  67         int gargc;
  68         char *gargv[1000];
  69         extern char **glob(), **copyblk();
  70 #endif
  71
  72         if ((*type != 'r' && *type != 'w') || type[1])
  73                 return(NULL);
  74
  75         if (!pids) {
  76                 if ((fds = getdtablesize()) <= 0)
  77                         return(NULL);
  78                 if (!(pids = (PID_T *)malloc((u_int)(fds * sizeof(PID_T)))))
  79                         return(NULL);
  80                 bzero((char *)pids, fds * sizeof(PID_T));
  81         }
  82         if (pipe(pdes) < 0)
  83                 return(NULL);
  84
  85         /* break up string into pieces */
  86         for (argc = 0, cp = program; argc < MAX_ARGS; cp = NULL)
  87                 if (!(argv[argc++] = strtok(cp, " \t\n")))
  88                         break;
  89         argv[MAX_ARGS] = NULL;
  90
  91 #if WANT_GLOBBING
  92         /* glob each piece */
  93         gargv[0] = argv[0];
  94         for (gargc = argc = 1; argv[argc]; argc++) {
  95                 if (!(pop = glob(argv[argc]))) {        /* globbing failed */
  96                         vv[0] = argv[argc];
  97                         vv[1] = NULL;
  98                         pop = copyblk(vv);
  99                 }
 100                 argv[argc] = (char *)pop;               /* save to free later */
 101                 while (*pop && gargc < 1000)
 102                         gargv[gargc++] = *pop++;
 103         }
 104         gargv[gargc] = NULL;
 105 #endif
 106
 107         iop = NULL;
 108         switch(pid = vfork()) {
 109         case -1:                        /* error */
 110                 (void)close(pdes[0]);
 111                 (void)close(pdes[1]);
 112                 goto pfree;
 113                 /* NOTREACHED */
 114         case 0:                         /* child */
 115                 if (e != NULL) {
 116 #ifdef SYSLOG
 117                         closelog();
 118 #endif
 119
 120                         /* get new pgrp, void tty, etc.
 121                          */
 122                         (void) setsid();
 123                 }
 124                 if (*type == 'r') {
 125                         /* Do not share our parent's stdin */
 126                         (void)close(0);
 127                         (void)open(_PATH_DEVNULL, O_RDWR);
 128                         if (pdes[1] != 1) {
 129                                 dup2(pdes[1], 1);
 130                                 dup2(pdes[1], 2);       /* stderr, too! */
 131                                 (void)close(pdes[1]);
 132                         }
 133                         (void)close(pdes[0]);
 134                 } else {
 135                         if (pdes[0] != 0) {
 136                                 dup2(pdes[0], 0);
 137                                 (void)close(pdes[0]);
 138                         }
 139                         /* Hack: stdout gets revoked */
 140                         (void)close(1);
 141                         (void)open(_PATH_DEVNULL, O_RDWR);
 142                         (void)close(2);
 143                         (void)open(_PATH_DEVNULL, O_RDWR);
 144                         (void)close(pdes[1]);
 145                 }
 146 # if defined(LOGIN_CAP)
 147                 if (e != NULL) {
 148                         /* Set user's entire context, but skip the environment
 149                          * as cron provides a separate interface for this
 150                          */
 151                         usernm = env_get("LOGNAME", e->envp);
 152                         if ((pwd = getpwnam(usernm)) == NULL)
 153                                 pwd = getpwuid(e->uid);
 154                         lc = NULL;
 155                         if (pwd != NULL) {
 156                                 pwd->pw_gid = e->gid;
 157                                 if (e->class != NULL)
 158                                         lc = login_getclass(e->class);
 159                         }
 160                         if (pwd &&
 161                             setusercontext(lc, pwd, e->uid,
 162                                     LOGIN_SETALL & ~(LOGIN_SETPATH|LOGIN_SETENV)) == 0)
 163                                 (void) endpwent();
 164                         else {
 165                                 /* fall back to the old method */
 166                                 (void) endpwent();
 167 # endif
 168                                 /* set our directory, uid and gid.  Set gid first,
 169                                  * since once we set uid, we've lost root privledges.
 170                                  */
 171                                 setgid(e->gid);
 172 # if defined(BSD)
 173                                 initgroups(usernm, e->gid);
 174 # endif
 175                                 setlogin(usernm);
 176                                 setuid(e->uid);         /* we aren't root after this..*/
 177 #if defined(LOGIN_CAP)
 178                         }
 179                         if (lc != NULL)
 180                                 login_close(lc);
 181 #endif
 182                         chdir(env_get("HOME", e->envp));
 183                 }
 184 #if WANT_GLOBBING
 185                 execvp(gargv[0], gargv);
 186 #else
 187                 execvp(argv[0], argv);
 188 #endif
 189                 _exit(1);
 190         }
 191         /* parent; assume fdopen can't fail...  */
 192         if (*type == 'r') {
 193                 iop = fdopen(pdes[0], type);
 194                 (void)close(pdes[1]);
 195         } else {
 196                 iop = fdopen(pdes[1], type);
 197                 (void)close(pdes[0]);
 198         }
 199         pids[fileno(iop)] = pid;
 200
 201 pfree:
 202 #if WANT_GLOBBING
 203         for (argc = 1; argv[argc] != NULL; argc++) {
 204 /*              blkfree((char **)argv[argc]);   */
 205                 free((char *)argv[argc]);
 206         }
 207 #endif
 208         return(iop);
 209 }
 210
 211 int
 212 cron_pclose(FILE *iop)
 213 {
 214         int fdes;
 215         int omask;
 216         WAIT_T stat_loc;
 217         PID_T pid;
 218
 219         /*
 220          * pclose returns -1 if stream is not associated with a
 221          * `popened' command, or, if already `pclosed'.
 222          */
 223         if (pids == 0 || pids[fdes = fileno(iop)] == 0)
 224                 return(-1);
 225         (void)fclose(iop);
 226         omask = sigblock(sigmask(SIGINT)|sigmask(SIGQUIT)|sigmask(SIGHUP));
 227         while ((pid = wait(&stat_loc)) != pids[fdes] && pid != -1)
 228                 ;
 229         (void)sigsetmask(omask);
 230         pids[fdes] = 0;
 231         return (pid == -1 ? -1 : WEXITSTATUS(stat_loc));
 232 }