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 static const char rcsid[] =
  28     "$Id: popen.c,v 1.3 1998/08/14 00:32:41 vixie Exp $";
  29 #if 0
  30 static const char sccsid[] = "@(#)popen.c       5.7 (Berkeley) 2/14/89";
  31 #endif
  32 #endif /* not lint */
  33
  34 #include "cron.h"
  35 #if defined(LOGIN_CAP)
  36 # include <login_cap.h>
  37 #endif
  38
  39 #define MAX_ARGS 100
  40 #define WANT_GLOBBING 0
  41
  42 /*
  43  * Special version of popen which avoids call to shell.  This insures no one
  44  * may create a pipe to a hidden program as a side effect of a list or dir
  45  * command.
  46  */
  47 static PID_T *pids;
  48 static int fds;
  49
  50 FILE *
  51 cron_popen(char *program, char *type, entry *e, PID_T *pidptr)
  52 {
  53         char *cp;
  54         FILE *iop;
  55         int argc, pdes[2];
  56         PID_T pid;
  57         char *usernm;
  58         char *argv[MAX_ARGS + 1];
  59 # if defined(LOGIN_CAP)
  60         struct passwd   *pwd;
  61         login_cap_t *lc;
  62 # endif
  63 #if WANT_GLOBBING
  64         char **pop, *vv[2];
  65         int gargc;
  66         char *gargv[1000];
  67         extern char **glob(), **copyblk();
  68 #endif
  69
  70         if ((*type != 'r' && *type != 'w') || type[1] != '\0')
  71                 return (NULL);
  72
  73         if (!pids) {
  74                 if ((fds = sysconf(_SC_OPEN_MAX)) <= 0)
  75                         return (NULL);
  76                 if (!(pids = calloc(fds, sizeof(PID_T))))
  77                         return (NULL);
  78         }
  79         if (pipe(pdes) < 0)
  80                 return (NULL);
  81
  82         /* break up string into pieces */
  83         for (argc = 0, cp = program; argc < MAX_ARGS; cp = NULL)
  84                 if (!(argv[argc++] = strtok(cp, " \t\n")))
  85                         break;
  86         argv[MAX_ARGS] = NULL;
  87
  88 #if WANT_GLOBBING
  89         /* glob each piece */
  90         gargv[0] = argv[0];
  91         for (gargc = argc = 1; argv[argc]; argc++) {
  92                 if (!(pop = glob(argv[argc]))) {        /* globbing failed */
  93                         vv[0] = argv[argc];
  94                         vv[1] = NULL;
  95                         pop = copyblk(vv);
  96                 }
  97                 argv[argc] = (char *)pop;               /* save to free later */
  98                 while (*pop && gargc < 1000)
  99                         gargv[gargc++] = *pop++;
 100         }
 101         gargv[gargc] = NULL;
 102 #endif
 103
 104         iop = NULL;
 105         switch(pid = fork()) {
 106         case -1:                        /* error */
 107                 (void)close(pdes[0]);
 108                 (void)close(pdes[1]);
 109                 goto pfree;
 110                 /* NOTREACHED */
 111         case 0:                         /* child */
 112                 if (e != NULL) {
 113 #ifdef SYSLOG
 114                         closelog();
 115 #endif
 116
 117                         /* get new pgrp, void tty, etc.
 118                          */
 119                         (void) setsid();
 120                 }
 121                 if (*type == 'r') {
 122                         /* Do not share our parent's stdin */
 123                         (void)close(0);
 124                         (void)open(_PATH_DEVNULL, O_RDWR);
 125                         if (pdes[1] != 1) {
 126                                 dup2(pdes[1], 1);
 127                                 dup2(pdes[1], 2);       /* stderr, too! */
 128                                 (void)close(pdes[1]);
 129                         }
 130                         (void)close(pdes[0]);
 131                 } else {
 132                         if (pdes[0] != 0) {
 133                                 dup2(pdes[0], 0);
 134                                 (void)close(pdes[0]);
 135                         }
 136                         /* Hack: stdout gets revoked */
 137                         (void)close(1);
 138                         (void)open(_PATH_DEVNULL, O_RDWR);
 139                         (void)close(2);
 140                         (void)open(_PATH_DEVNULL, O_RDWR);
 141                         (void)close(pdes[1]);
 142                 }
 143                 if (e != NULL) {
 144                         /* Set user's entire context, but skip the environment
 145                          * as cron provides a separate interface for this
 146                          */
 147                         usernm = env_get("LOGNAME", e->envp);
 148 # if defined(LOGIN_CAP)
 149                         if ((pwd = getpwnam(usernm)) == NULL)
 150                                 pwd = getpwuid(e->uid);
 151                         lc = NULL;
 152                         if (pwd != NULL) {
 153                                 pwd->pw_gid = e->gid;
 154                                 if (e->class != NULL)
 155                                         lc = login_getclass(e->class);
 156                         }
 157                         if (pwd &&
 158                             setusercontext(lc, pwd, e->uid,
 159                                     LOGIN_SETALL & ~(LOGIN_SETPATH|LOGIN_SETENV)) == 0)
 160                                 (void) endpwent();
 161                         else {
 162                                 /* fall back to the old method */
 163                                 (void) endpwent();
 164 # endif
 165                                 /*
 166                                  * Set our directory, uid and gid.  Set gid
 167                                  * first since once we set uid, we've lost
 168                                  * root privileges.
 169                                  */
 170                                 if (setgid(e->gid) != 0)
 171                                         _exit(ERROR_EXIT);
 172 # if defined(BSD)
 173                                 if (initgroups(usernm, e->gid) != 0)
 174                                         _exit(ERROR_EXIT);
 175 # endif
 176                                 if (setlogin(usernm) != 0)
 177                                         _exit(ERROR_EXIT);
 178                                 if (setuid(e->uid) != 0)
 179                                         _exit(ERROR_EXIT);
 180                                 /* we aren't root after this..*/
 181 #if defined(LOGIN_CAP)
 182                         }
 183                         if (lc != NULL)
 184                                 login_close(lc);
 185 #endif
 186                         chdir(env_get("HOME", e->envp));
 187                 }
 188 #if WANT_GLOBBING
 189                 execvp(gargv[0], gargv);
 190 #else
 191                 execvp(argv[0], argv);
 192 #endif
 193                 _exit(1);
 194         }
 195         /* parent; assume fdopen can't fail...  */
 196         if (*type == 'r') {
 197                 iop = fdopen(pdes[0], type);
 198                 (void)close(pdes[1]);
 199         } else {
 200                 iop = fdopen(pdes[1], type);
 201                 (void)close(pdes[0]);
 202         }
 203         pids[fileno(iop)] = pid;
 204
 205 pfree:
 206 #if WANT_GLOBBING
 207         for (argc = 1; argv[argc] != NULL; argc++) {
 208 /*              blkfree((char **)argv[argc]);   */
 209                 free((char *)argv[argc]);
 210         }
 211 #endif
 212
 213         *pidptr = pid;
 214
 215         return (iop);
 216 }
 217
 218 int
 219 cron_pclose(FILE *iop)
 220 {
 221         int fdes;
 222         int omask;
 223         WAIT_T stat_loc;
 224         PID_T pid;
 225
 226         /*
 227          * pclose returns -1 if stream is not associated with a
 228          * `popened' command, or, if already `pclosed'.
 229          */
 230         if (pids == 0 || pids[fdes = fileno(iop)] == 0)
 231                 return (-1);
 232         (void)fclose(iop);
 233         omask = sigblock(sigmask(SIGINT)|sigmask(SIGQUIT)|sigmask(SIGHUP));
 234         while ((pid = wait(&stat_loc)) != pids[fdes] && pid != -1)
 235                 ;
 236         (void)sigsetmask(omask);
 237         pids[fdes] = 0;
 238         return (pid == -1 ? -1 : WEXITSTATUS(stat_loc));
 239 }