allow root to edit encrypted passwords

[unix-history] / usr / src / usr.bin / chpass / chpass.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 MERCHANTABILITY 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[] = "@(#)chpass.c    5.6 (Berkeley) %G%";
#endif /* not lint */

#include <sys/param.h>
#include <sys/file.h>
#include <sys/stat.h>
#include <sys/signal.h>
#include <sys/time.h>
#include <sys/resource.h>
#include </usr/src/include/pwd.h>
#include <errno.h>
#include <stdio.h>
#include <ctype.h>
#include <chpass.h>
#include <strings.h>

char e1[] = ": ";
char e2[] = ":,";

int p_change(), p_class(), p_expire(), p_gecos(), p_gid(), p_hdir();
int p_login(), p_passwd(), p_shell(), p_uid();

struct entry list[] = {
       { "Login",              p_login,  1,   5, e1,   },
       { "Password",           p_passwd, 1,   8, e1,   },
       { "Uid",                p_uid,    1,   3, e1,   },
       { "Gid",                p_gid,    1,   3, e1,   },
       { "Class",              p_class,  1,   5, e1,   },
       { "Change",             p_change, 1,   6, NULL, },
       { "Expire",             p_expire, 1,   6, NULL, },
#define E_NAME          6
       { "Full Name",          p_gecos,  0,   9, e2,   },
#define E_BPHONE        7
       { "Office Phone",       p_gecos,  0,  12, e2,   },
#define E_HPHONE        8
       { "Home Phone",         p_gecos,  0,  10, e2,   },
#define E_LOCATE        9
       { "Location",           p_gecos,  0,   8, e2,   },
       { "Home directory",     p_hdir,   1,  14, e1,   },
       { "Shell",              p_shell,  0,   5, e1,   },
       { NULL, 0, },
};

uid_t euid, uid;

main(argc, argv)
       int argc;
       char **argv;
{
       extern int errno;
       register char *p;
       struct passwd *pw;
       struct rlimit rlim;
       FILE *temp_fp;
       int fd;
       char *fend, *passwd, *temp, *tend, buf[1024];
       char from[MAXPATHLEN], to[MAXPATHLEN];
       char *getusershell();

       euid = geteuid();
       uid = getuid();
       switch(--argc) {
       case 0:
               if (!(pw = getpwuid(uid))) {
                       fprintf(stderr, "chpass: unknown user: uid %u\n", uid);
                       exit(1);
               }
               break;
       case 1:
               if (!(pw = getpwnam(argv[1]))) {
                       fprintf(stderr, "chpass: unknown user %s.\n", argv[1]);
                       exit(1);
               }
               if (uid && uid != pw->pw_uid) {
                       fprintf(stderr, "chpass: %s\n", strerror(EACCES));
                       exit(1);
               }
               break;
       default:
               fprintf(stderr, "usage: chpass [user]\n");
               exit(1);
       }

       (void)signal(SIGHUP, SIG_IGN);
       (void)signal(SIGINT, SIG_IGN);
       (void)signal(SIGQUIT, SIG_IGN);
       (void)signal(SIGTSTP, SIG_IGN);

       rlim.rlim_cur = rlim.rlim_max = RLIM_INFINITY;
       (void)setrlimit(RLIMIT_CPU, &rlim);
       (void)setrlimit(RLIMIT_FSIZE, &rlim);

       (void)umask(0);

       temp = _PATH_PTMP;
       if ((fd = open(temp, O_WRONLY|O_CREAT|O_EXCL, 0600)) < 0) {
               if (errno == EEXIST) {
                       fprintf(stderr,
                           "chpass: password file busy -- try again later.\n");
                       exit(1);
               }
               fprintf(stderr, "chpass: %s: %s", temp, strerror(errno));
               goto bad;
       }
       if (!(temp_fp = fdopen(fd, "w"))) {
               fprintf(stderr, "chpass: can't write %s", temp);
               goto bad;
       }

       if (!info(pw))
               goto bad;

       /*
        * special checks...
        *
        * there has to be a limit on the size of the gecos fields,
        * otherwise getpwent(3) can choke.
        * ``if I swallow anything evil, put your fingers down my throat...''
        *      -- The Who
        */
       if (strlen(list[E_NAME].save) + strlen(list[E_BPHONE].save) +
           strlen(list[E_HPHONE].save) + strlen(list[E_LOCATE].save)
           > 512) {
               fprintf(stderr, "chpass: gecos field too large.\n");
               exit(1);
       }
       (void)sprintf(pw->pw_gecos = buf, "%s,%s,%s,%s",
           list[E_NAME].save, list[E_LOCATE].save, list[E_BPHONE].save,
           list[E_HPHONE].save);

       /* root should have a 0 uid and a reasonable shell */
       if (!strcmp(pw->pw_name, "root")) {
               if (pw->pw_uid) {
                       fprintf(stderr, "chpass: root uid should be 0.");
                       exit(1);
               }
               setusershell();
               for (;;)
                       if (!(p = getusershell())) {
                               fprintf(stderr,
                                   "chpass: warning, unknown root shell.");
                               break;
                       }
                       else if (!strcmp(pw->pw_shell, p))
                               break;
       }

       passwd = _PATH_MASTERPASSWD;
       if (!freopen(passwd, "r", stdin)) {
               fprintf(stderr, "chpass: can't read %s", passwd);
               goto bad;
       }
       if (!copy(pw, temp_fp))
               goto bad;

       (void)fclose(temp_fp);
       (void)fclose(stdin);

       switch(fork()) {
       case 0:
               break;
       case -1:
               fprintf(stderr, "chpass: can't fork");
               goto bad;
               /* NOTREACHED */
       default:
               exit(0);
               /* NOTREACHED */
       }

       if (makedb(temp)) {
               fprintf(stderr, "chpass: mkpasswd failed");
bad:            fprintf(stderr, "; information unchanged.\n");
               (void)unlink(temp);
               exit(1);
       }

       /*
        * possible race; have to rename four files, and someone could slip
        * in between them.  LOCK_EX and rename the ``passwd.dir'' file first
        * so that getpwent(3) can't slip in; the lock should never fail and
        * it's unclear what to do if it does.  Rename ``ptmp'' last so that
        * passwd/vipw/chpass can't slip in.
        */
       (void)setpriority(PRIO_PROCESS, 0, -20);
       fend = strcpy(from, temp) + strlen(temp);
       tend = strcpy(to, passwd) + strlen(passwd);
       bcopy(".dir", fend, 5);
       bcopy(".dir", tend, 5);
       if ((fd = open(from, O_RDONLY, 0)) >= 0)
               (void)flock(fd, LOCK_EX);
       /* here we go... */
       (void)rename(from, to);
       bcopy(".pag", fend, 5);
       bcopy(".pag", tend, 5);
       (void)rename(from, to);
       bcopy(".orig", fend, 6);
       (void)rename(from, _PATH_PASSWD);
       (void)rename(temp, passwd);
       /* done! */
       exit(0);
}

info(pw)
       struct passwd *pw;
{
       register struct entry *ep;
       register char *p;
       struct stat begin, end;
       FILE *fp;
       int fd, rval;
       char *tfile, buf[1024], *getenv();

       tfile = "/tmp/passwd.XXXXXX";
       if ((fd = mkstemp(tfile)) == -1 || !(fp = fdopen(fd, "w+"))) {
               fprintf(stderr, "chpass: no temporary file");
               return(0);
       }

       print(fp, pw);
       (void)fflush(fp);

       /*
        * give the file to the real user; setuid permissions
        * are discarded in edit()
        */
       (void)fchown(fd, getuid(), getgid());
       (void)fstat(fd, &begin);
       rval = edit(tfile);
       (void)unlink(tfile);

       if (rval) {
               fprintf(stderr, "chpass: edit failed");
               return(0);
       }
       (void)fstat(fd, &end);
       if (begin.st_mtime == end.st_mtime) {
               fprintf(stderr, "chpass: no changes made");
               return(0);
       }
       (void)rewind(fp);
       while (fgets(buf, sizeof(buf), fp)) {
               if (!buf[0])
                       continue;
               if (!(p = index(buf, '\n'))) {
                       fprintf(stderr, "chpass: line too long");
                       return(0);
               }
               *p = '\0';
               for (ep = list; ep->prompt; ++ep)
                       if (!strncasecmp(buf, ep->prompt, ep->len)) {
                               if (ep->restricted && euid)
                                       continue;
                               if (!(p = index(buf, ':'))) {
                                       fprintf(stderr,
                                           "chpass: line corrupted");
                                       return(0);
                               }
                               while (isspace(*++p));
                               if (ep->except && strpbrk(p, ep->except)) {
                                       fprintf(stderr,
                                          "chpass: illegal character in the \"%s\" field",
                                           ep->prompt);
                                       return(0);
                               }
                               if ((ep->func)(p, pw, ep))
                                       return(0);
                               break;
                       }
       }
       (void)fclose(fp);
       return(1);
}

copy(pw, fp)
       struct passwd *pw;
       FILE *fp;
{
       register int done;
       register char *p;
       char buf[1024];

       for (done = 0; fgets(buf, sizeof(buf), stdin);) {
               /* skip lines that are too big */
               if (!index(buf, '\n')) {
                       fprintf(stderr, "chpass: line too long");
                       return(0);
               }
               if (done) {
                       fprintf(fp, "%s", buf);
                       continue;
               }
               if (!(p = index(buf, ':'))) {
                       fprintf(stderr, "chpass: corrupted entry");
                       return(0);
               }
               *p = '\0';
               if (strcmp(buf, pw->pw_name)) {
                       *p = ':';
                       fprintf(fp, "%s", buf);
                       continue;
               }
               fprintf(fp, "%s:%s:%d:%d:%s:%ld:%ld:%s:%s:%s\n",
                   pw->pw_name, pw->pw_passwd, pw->pw_uid, pw->pw_gid,
                   pw->pw_class, pw->pw_change, pw->pw_expire, pw->pw_gecos,
                   pw->pw_dir, pw->pw_shell);
               done = 1;
       }
       if (!done)
               fprintf(fp, "%s:%s:%d:%d:%s:%ld:%ld:%s:%s:%s\n",
                   pw->pw_name, pw->pw_passwd, pw->pw_uid, pw->pw_gid,
                   pw->pw_class, pw->pw_change, pw->pw_expire, pw->pw_gecos,
                   pw->pw_dir, pw->pw_shell);
       return(1);
}

makedb(file)
       char *file;
{
       int status, pid, w;

       if (!(pid = vfork())) {
               execl(_PATH_MKPASSWD, "mkpasswd", "-p", file, NULL);
               _exit(127);
       }
       while ((w = wait(&status)) != pid && w != -1);
       return(w == -1 || status);
}

edit(file)
       char *file;
{
       int status, pid, w;
       char *p, *editor, *getenv();

       if (editor = getenv("EDITOR")) {
               if (p = rindex(editor, '/'))
                       ++p;
               else
                       p = editor;
       }
       else
               p = editor = "vi";
       if (!(pid = vfork())) {
               (void)setuid(getuid());
               (void)setgid(getgid());
               execlp(editor, p, file, NULL);
               _exit(127);
       }
       while ((w = wait(&status)) != pid && w != -1);
       return(w == -1 || status);
}