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  */
  21
  22 /* this came out of the ftpd sources; it's been modified to avoid the
  23  * globbing stuff since we don't need it.  also execvp instead of execv.
  24  */
  25
  26 #ifndef lint
  27 #if 0
  28 static char sccsid[] = "@(#)popen.c     5.7 (Berkeley) 2/14/89";
  29 #endif
  30 static const char rcsid[] =
  31   "$FreeBSD$";
  32 #endif /* not lint */
  33
  34 #include "cron.h"
  35 #include <sys/signal.h>
  36 #include <fcntl.h>
  37 #include <paths.h>
  38 #if defined(SYSLOG)
  39 # include <syslog.h>
  40 #endif
  41 #if defined(LOGIN_CAP)
  42 # include <login_cap.h>
  43 #endif
  44
  45
  46 #define MAX_ARGS 100
  47 #define WANT_GLOBBING 0
  48
  49 /*
  50  * Special version of popen which avoids call to shell.  This insures noone
  51  * may create a pipe to a hidden program as a side effect of a list or dir
  52  * command.
  53  */
  54 static PID_T *pids;
  55 static int fds;
  56
  57 FILE *
  58 cron_popen(program, type, e)
  59         char *program, *type;
  60         entry *e;
  61 {
  62         register char *cp;
  63         FILE *iop;
  64         int argc, pdes[2];
  65         PID_T pid;
  66         char *usernm;
  67         char *argv[MAX_ARGS + 1];
  68 # if defined(LOGIN_CAP)
  69         struct passwd   *pwd;
  70         login_cap_t *lc;
  71 # endif
  72 #if WANT_GLOBBING
  73         char **pop, *vv[2];
  74         int gargc;
  75         char *gargv[1000];
  76         extern char **glob(), **copyblk();
  77 #endif
  78
  79         if ((*type != 'r' && *type != 'w') || type[1])
  80                 return(NULL);
  81
  82         if (!pids) {
  83                 if ((fds = getdtablesize()) <= 0)
  84                         return(NULL);
  85                 if (!(pids = calloc(fds, sizeof(PID_T))))
  86                         return(NULL);
  87         }
  88         if (pipe(pdes) < 0)
  89                 return(NULL);
  90
  91         /* break up string into pieces */
  92         for (argc = 0, cp = program; argc < MAX_ARGS; cp = NULL)
  93                 if (!(argv[argc++] = strtok(cp, " \t\n")))
  94                         break;
  95         argv[MAX_ARGS] = NULL;
  96
  97 #if WANT_GLOBBING
  98         /* glob each piece */
  99         gargv[0] = argv[0];
 100         for (gargc = argc = 1; argv[argc]; argc++) {
 101                 if (!(pop = glob(argv[argc]))) {        /* globbing failed */
 102                         vv[0] = argv[argc];
 103                         vv[1] = NULL;
 104                         pop = copyblk(vv);
 105                 }
 106                 argv[argc] = (char *)pop;               /* save to free later */
 107                 while (*pop && gargc < 1000)
 108                         gargv[gargc++] = *pop++;
 109         }
 110         gargv[gargc] = NULL;
 111 #endif
 112
 113         iop = NULL;
 114         switch(pid = vfork()) {
 115         case -1:                        /* error */
 116                 (void)close(pdes[0]);
 117                 (void)close(pdes[1]);
 118                 goto pfree;
 119                 /* NOTREACHED */
 120         case 0:                         /* child */
 121                 if (e != NULL) {
 122 #ifdef SYSLOG
 123                         closelog();
 124 #endif
 125
 126                         /* get new pgrp, void tty, etc.
 127                          */
 128                         (void) setsid();
 129                 }
 130                 if (*type == 'r') {
 131                         /* Do not share our parent's stdin */
 132                         (void)close(0);
 133                         (void)open(_PATH_DEVNULL, O_RDWR);
 134                         if (pdes[1] != 1) {
 135                                 dup2(pdes[1], 1);
 136                                 dup2(pdes[1], 2);       /* stderr, too! */
 137                                 (void)close(pdes[1]);
 138                         }
 139                         (void)close(pdes[0]);
 140                 } else {
 141                         if (pdes[0] != 0) {
 142                                 dup2(pdes[0], 0);
 143                                 (void)close(pdes[0]);
 144                         }
 145                         /* Hack: stdout gets revoked */
 146                         (void)close(1);
 147                         (void)open(_PATH_DEVNULL, O_RDWR);
 148                         (void)close(2);
 149                         (void)open(_PATH_DEVNULL, O_RDWR);
 150                         (void)close(pdes[1]);
 151                 }
 152                 if (e != NULL) {
 153                         /* Set user's entire context, but skip the environment
 154                          * as cron provides a separate interface for this
 155                          */
 156                         usernm = env_get("LOGNAME", e->envp);
 157 # if defined(LOGIN_CAP)
 158                         if ((pwd = getpwnam(usernm)) == NULL)
 159                                 pwd = getpwuid(e->uid);
 160                         lc = NULL;
 161                         if (pwd != NULL) {
 162                                 pwd->pw_gid = e->gid;
 163                                 if (e->class != NULL)
 164                                         lc = login_getclass(e->class);
 165                         }
 166                         if (pwd &&
 167                             setusercontext(lc, pwd, e->uid,
 168                                     LOGIN_SETALL & ~(LOGIN_SETPATH|LOGIN_SETENV)) == 0)
 169                                 (void) endpwent();
 170                         else {
 171                                 /* fall back to the old method */
 172                                 (void) endpwent();
 173 # endif
 174                                 /*
 175                                  * Set our directory, uid and gid.  Set gid
 176                                  * first since once we set uid, we've lost
 177                                  * root privileges.
 178                                  */
 179                                 if (setgid(e->gid) != 0)
 180                                         _exit(ERROR_EXIT);
 181 # if defined(BSD)
 182                                 if (initgroups(usernm, e->gid) != 0)
 183                                         _exit(ERROR_EXIT);
 184 # endif
 185                                 if (setlogin(usernm) != 0)
 186                                         _exit(ERROR_EXIT);
 187                                 if (setuid(e->uid) != 0)
 188                                         _exit(ERROR_EXIT);
 189                                 /* we aren't root after this..*/
 190 #if defined(LOGIN_CAP)
 191                         }
 192                         if (lc != NULL)
 193                                 login_close(lc);
 194 #endif
 195                         chdir(env_get("HOME", e->envp));
 196                 }
 197 #if WANT_GLOBBING
 198                 execvp(gargv[0], gargv);
 199 #else
 200                 execvp(argv[0], argv);
 201 #endif
 202                 _exit(1);
 203         }
 204         /* parent; assume fdopen can't fail...  */
 205         if (*type == 'r') {
 206                 iop = fdopen(pdes[0], type);
 207                 (void)close(pdes[1]);
 208         } else {
 209                 iop = fdopen(pdes[1], type);
 210                 (void)close(pdes[0]);
 211         }
 212         pids[fileno(iop)] = pid;
 213
 214 pfree:
 215 #if WANT_GLOBBING
 216         for (argc = 1; argv[argc] != NULL; argc++) {
 217 /*              blkfree((char **)argv[argc]);   */
 218                 free((char *)argv[argc]);
 219         }
 220 #endif
 221         return(iop);
 222 }
 223
 224 int
 225 cron_pclose(iop)
 226         FILE *iop;
 227 {
 228         register int fdes;
 229         int omask;
 230         WAIT_T stat_loc;
 231         PID_T pid;
 232
 233         /*
 234          * pclose returns -1 if stream is not associated with a
 235          * `popened' command, or, if already `pclosed'.
 236          */
 237         if (pids == 0 || pids[fdes = fileno(iop)] == 0)
 238                 return(-1);
 239         (void)fclose(iop);
 240         omask = sigblock(sigmask(SIGINT)|sigmask(SIGQUIT)|sigmask(SIGHUP));
 241         while ((pid = wait(&stat_loc)) != pids[fdes] && pid != -1)
 242                 ;
 243         (void)sigsetmask(omask);
 244         pids[fdes] = 0;
 245         return (pid == -1 ? -1 : WEXITSTATUS(stat_loc));
 246 }