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  */
  23
  24 /* this came out of the ftpd sources; it's been modified to avoid the
  25  * globbing stuff since we don't need it.  also execvp instead of execv.
  26  */
  27
  28 #include "cron.h"
  29 #include <sys/signal.h>
  30 #include <fcntl.h>
  31 #include <paths.h>
  32 #if defined(SYSLOG)
  33 # include <syslog.h>
  34 #endif
  35 #if defined(LOGIN_CAP)
  36 # include <login_cap.h>
  37 #endif
  38
  39
  40 #define MAX_ARGS 100
  41 #define WANT_GLOBBING 0
  42
  43 /*
  44  * Special version of popen which avoids call to shell.  This insures noone
  45  * may create a pipe to a hidden program as a side effect of a list or dir
  46  * command.
  47  */
  48 static PID_T *pids;
  49 static int fds;
  50
  51 FILE *
  52 cron_popen(char *program, char *type, entry *e)
  53 {
  54         char *cp;
  55         FILE *iop;
  56         int argc, pdes[2];
  57         PID_T pid;
  58         char *usernm;
  59         char *argv[MAX_ARGS + 1];
  60 # if defined(LOGIN_CAP)
  61         struct passwd   *pwd;
  62         login_cap_t *lc;
  63 # endif
  64 #if WANT_GLOBBING
  65         char **pop, *vv[2];
  66         int gargc;
  67         char *gargv[1000];
  68         extern char **glob(), **copyblk();
  69 #endif
  70
  71         if ((*type != 'r' && *type != 'w') || type[1])
  72                 return(NULL);
  73
  74         if (!pids) {
  75                 if ((fds = getdtablesize()) <= 0)
  76                         return(NULL);
  77                 if (!(pids = (PID_T *)malloc((u_int)(fds * sizeof(PID_T)))))
  78                         return(NULL);
  79                 bzero((char *)pids, fds * sizeof(PID_T));
  80         }
  81         if (pipe(pdes) < 0)
  82                 return(NULL);
  83
  84         /* break up string into pieces */
  85         for (argc = 0, cp = program; argc < MAX_ARGS; cp = NULL)
  86                 if (!(argv[argc++] = strtok(cp, " \t\n")))
  87                         break;
  88         argv[MAX_ARGS] = NULL;
  89
  90 #if WANT_GLOBBING
  91         /* glob each piece */
  92         gargv[0] = argv[0];
  93         for (gargc = argc = 1; argv[argc]; argc++) {
  94                 if (!(pop = glob(argv[argc]))) {        /* globbing failed */
  95                         vv[0] = argv[argc];
  96                         vv[1] = NULL;
  97                         pop = copyblk(vv);
  98                 }
  99                 argv[argc] = (char *)pop;               /* save to free later */
 100                 while (*pop && gargc < 1000)
 101                         gargv[gargc++] = *pop++;
 102         }
 103         gargv[gargc] = NULL;
 104 #endif
 105
 106         iop = NULL;
 107         switch(pid = vfork()) {
 108         case -1:                        /* error */
 109                 close(pdes[0]);
 110                 close(pdes[1]);
 111                 goto pfree;
 112                 /* NOTREACHED */
 113         case 0:                         /* child */
 114                 if (e != NULL) {
 115 #ifdef SYSLOG
 116                         closelog();
 117 #endif
 118
 119                         /* get new pgrp, void tty, etc.
 120                          */
 121                         setsid();
 122                 }
 123                 if (*type == 'r') {
 124                         /* Do not share our parent's stdin */
 125                         close(0);
 126                         open(_PATH_DEVNULL, O_RDWR);
 127                         if (pdes[1] != 1) {
 128                                 dup2(pdes[1], 1);
 129                                 dup2(pdes[1], 2);       /* stderr, too! */
 130                                 close(pdes[1]);
 131                         }
 132                         close(pdes[0]);
 133                 } else {
 134                         if (pdes[0] != 0) {
 135                                 dup2(pdes[0], 0);
 136                                 close(pdes[0]);
 137                         }
 138                         /* Hack: stdout gets revoked */
 139                         close(1);
 140                         open(_PATH_DEVNULL, O_RDWR);
 141                         close(2);
 142                         open(_PATH_DEVNULL, O_RDWR);
 143                         close(pdes[1]);
 144                 }
 145 # if defined(LOGIN_CAP)
 146                 if (e != NULL) {
 147                         /* Set user's entire context, but skip the environment
 148                          * as cron provides a separate interface for this
 149                          */
 150                         usernm = env_get("LOGNAME", e->envp);
 151                         if ((pwd = getpwnam(usernm)) == NULL)
 152                                 pwd = getpwuid(e->uid);
 153                         lc = NULL;
 154                         if (pwd != NULL) {
 155                                 pwd->pw_gid = e->gid;
 156                                 if (e->class != NULL)
 157                                         lc = login_getclass(e->class);
 158                         }
 159                         if (pwd &&
 160                             setusercontext(lc, pwd, e->uid,
 161                                     LOGIN_SETALL & ~(LOGIN_SETPATH|LOGIN_SETENV)) == 0)
 162                                 endpwent();
 163                         else {
 164                                 /* fall back to the old method */
 165                                 endpwent();
 166 # endif
 167                                 /* set our directory, uid and gid.  Set gid first,
 168                                  * since once we set uid, we've lost root privledges.
 169                                  */
 170                                 setgid(e->gid);
 171 # if defined(BSD)
 172                                 initgroups(usernm, e->gid);
 173 # endif
 174                                 setlogin(usernm);
 175                                 setuid(e->uid);         /* we aren't root after this..*/
 176 #if defined(LOGIN_CAP)
 177                         }
 178                         if (lc != NULL)
 179                                 login_close(lc);
 180 #endif
 181                         chdir(env_get("HOME", e->envp));
 182                 }
 183 #if WANT_GLOBBING
 184                 execvp(gargv[0], gargv);
 185 #else
 186                 execvp(argv[0], argv);
 187 #endif
 188                 _exit(1);
 189         }
 190         /* parent; assume fdopen can't fail...  */
 191         if (*type == 'r') {
 192                 iop = fdopen(pdes[0], type);
 193                 close(pdes[1]);
 194         } else {
 195                 iop = fdopen(pdes[1], type);
 196                 close(pdes[0]);
 197         }
 198         pids[fileno(iop)] = pid;
 199
 200 pfree:
 201 #if WANT_GLOBBING
 202         for (argc = 1; argv[argc] != NULL; argc++) {
 203 /*              blkfree((char **)argv[argc]);   */
 204                 free((char *)argv[argc]);
 205         }
 206 #endif
 207         return(iop);
 208 }
 209
 210 int
 211 cron_pclose(FILE *iop)
 212 {
 213         int fdes;
 214         int omask;
 215         WAIT_T stat_loc;
 216         PID_T pid;
 217
 218         /*
 219          * pclose returns -1 if stream is not associated with a
 220          * `popened' command, or, if already `pclosed'.
 221          */
 222         if (pids == NULL || pids[fdes = fileno(iop)] == 0)
 223                 return(-1);
 224         fclose(iop);
 225         omask = sigblock(sigmask(SIGINT)|sigmask(SIGQUIT)|sigmask(SIGHUP));
 226         while ((pid = wait(&stat_loc)) != pids[fdes] && pid != -1)
 227                 ;
 228         sigsetmask(omask);
 229         pids[fdes] = 0;
 230         return (pid == -1 ? -1 : WEXITSTATUS(stat_loc));
 231 }