file reorg, pathnames.h, paths.h

[unix-history] / usr / src / usr.bin / su / su.c

/*
* Copyright (c) 1988 The Regents of the University of California.
* All rights reserved.
*
* Redistribution and use in source and binary forms are permitted
* provided that the above copyright notice and this paragraph are
* duplicated in all such forms and that any documentation,
* advertising materials, and other materials related to such
* distribution and use acknowledge that the software was developed
* by the University of California, Berkeley.  The name of the
* University may not be used to endorse or promote products derived
* from this software without specific prior written permission.
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
* WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*/

#ifndef lint
char copyright[] =
"@(#) Copyright (c) 1988 The Regents of the University of California.\n\
All rights reserved.\n";
#endif /* not lint */

#ifndef lint
static char sccsid[] = "@(#)su.c        5.12 (Berkeley) %G%";
#endif /* not lint */

#include <sys/param.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <syslog.h>
#include <stdio.h>
#include <pwd.h>
#include <grp.h>
#include "pathnames.h"

main(argc, argv)
       int argc;
       char **argv;
{
       extern char **environ;
       extern int errno, optind;
       register struct passwd *pwd;
       register char *p, **g;
       struct group *gr;
       uid_t ruid, getuid();
       int asme, ch, fulllogin, fastlogin, prio;
       enum { UNSET, YES, NO } iscsh = UNSET;
       char *user, *shell, *username, *cleanenv[2], *nargv[4], **np;
       char namebuf[50], shellbuf[MAXPATHLEN];
       char *crypt(), *getpass(), *getenv(), *getlogin(), *rindex(), *strcpy();

       np = &nargv[3];
       *np-- = NULL;
       asme = fulllogin = fastlogin = 0;
       while ((ch = getopt(argc, argv, "-flm")) != EOF)
               switch((char)ch) {
               case 'f':
                       fastlogin = 1;
                       break;
               case '-':
               case 'l':
                       fulllogin = 1;
                       break;
               case 'm':
                       asme = 1;
                       break;
               case '?':
               default:
                       fprintf(stderr, "usage: su [-flm] [login]\n");
                       exit(1);
               }
       argv += optind;

       errno = 0;
       prio = getpriority(PRIO_PROCESS, 0);
       if (errno)
               prio = 0;
       (void)setpriority(PRIO_PROCESS, 0, -2);

       /* get current login name and shell */
       if ((pwd = getpwuid(ruid = getuid())) == NULL) {
               fprintf(stderr, "su: who are you?\n");
               exit(1);
       }
       username = strcpy(namebuf, pwd->pw_name);
       if (asme)
               if (pwd->pw_shell && *pwd->pw_shell)
                       shell = strcpy(shellbuf,  pwd->pw_shell);
               else {
                       shell = _PATH_BSHELL;
                       iscsh = NO;
               }

       /* get target login information */
       user = *argv ? *argv : "root";
       if ((pwd = getpwnam(user)) == NULL) {
               fprintf(stderr, "su: unknown login %s\n", user);
               exit(1);
       }

       /* only allow those in group zero to su to root. */
       if (pwd->pw_uid == 0 && (gr = getgrgid((gid_t)0)))
               for (g = gr->gr_mem;; ++g) {
                       if (!*g) {
                               fprintf(stderr, "su: you are not in the correct group to su %s.\n", user);
                               exit(1);
                       }
                       if (!strcmp(username, *g))
                               break;
               }

       /* if target requires a password, verify it */
       if (ruid && *pwd->pw_passwd) {
               p = getpass("Password:");
               if (strcmp(pwd->pw_passwd, crypt(p, pwd->pw_passwd))) {
                       fprintf(stderr, "Sorry\n");
                       if (pwd->pw_uid == 0)
                               syslog(LOG_CRIT|LOG_AUTH, "su: BAD SU %s on %s", username, ttyname(2));
                       exit(1);
               }
       }

       if (asme) {
               /* if asme and non-standard target shell, must be root */
               if (!chshell(pwd->pw_shell) && ruid) {
                       fprintf(stderr, "su: Permission denied.\n");
                       exit(1);
               }
       }
       else if (pwd->pw_shell && *pwd->pw_shell) {
               shell = pwd->pw_shell;
               iscsh = UNSET;
       } else {
               shell = _PATH_BSHELL;
               iscsh = NO;
       }

       /* if we're forking a csh, we want to slightly muck the args */
       if (iscsh == UNSET) {
               if (p = rindex(shell, '/'))
                       ++p;
               else
                       p = shell;
               iscsh = strcmp(p, "csh") ? NO : YES;
       }

       /* set permissions */
       if (setgid(pwd->pw_gid) < 0) {
               perror("su: setgid");
               exit(1);
       }
       if (initgroups(user, pwd->pw_gid)) {
               fprintf(stderr, "su: initgroups failed\n");
               exit(1);
       }
       if (setuid(pwd->pw_uid) < 0) {
               perror("su: setuid");
               exit(1);
       }

       if (!asme) {
               if (fulllogin) {
                       p = getenv("TERM");
                       cleanenv[0] = _PATH_SEARCHPATH;
                       cleanenv[1] = NULL;
                       environ = cleanenv;
                       (void)setenv("TERM", p, 1);
                       if (chdir(pwd->pw_dir) < 0) {
                               fprintf(stderr, "su: no directory\n");
                               exit(1);
                       }
               }
               if (fulllogin || pwd->pw_uid)
                       (void)setenv("USER", pwd->pw_name, 1);
               (void)setenv("HOME", pwd->pw_dir, 1);
               (void)setenv("SHELL", shell, 1);
       }

       if (iscsh == YES) {
               if (fastlogin)
                       *np-- = "-f";
               if (asme)
                       *np-- = "-m";
       }

       /* csh strips the first character... */
       *np = fulllogin ? "-su" : iscsh == YES ? "_su" : "su";

       if (pwd->pw_uid == 0)
               syslog(LOG_NOTICE|LOG_AUTH, "su: %s on %s",
                   username, ttyname(2));

       (void)setpriority(PRIO_PROCESS, 0, prio);

       execv(shell, np);
       fprintf(stderr, "su: no shell.\n");
       exit(1);
}

chshell(sh)
       char *sh;
{
       char *cp, *getusershell();

       while ((cp = getusershell()) != NULL)
               if (!strcmp(cp, sh))
                       return(1);
       return(0);
}