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/*
* lib/krb4/in_tkt.c
*
* Copyright 1985, 1986, 1987, 1988, 2000, 2001 by the Massachusetts
* Institute of Technology. All Rights Reserved.
*
* Export of this software from the United States of America may
* require a specific license from the United States Government.
* It is the responsibility of any person or organization contemplating
* export to obtain such a license before exporting.
*
* WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
* distribute this software and its documentation for any purpose and
* without fee is hereby granted, provided that the above copyright
* notice appear in all copies and that both that copyright notice and
* this permission notice appear in supporting documentation, and that
* the name of M.I.T. not be used in advertising or publicity pertaining
* to distribution of the software without specific, written prior
* permission. Furthermore if you modify this software you must label
* your software as modified software and not distribute it in such a
* fashion that it might be confused with the original M.I.T. software.
* M.I.T. makes no representations about the suitability of
* this software for any purpose. It is provided "as is" without express
* or implied warranty.
*/
#include <stdio.h>
#include <string.h>
#include "krb.h"
#include <fcntl.h>
#include <sys/stat.h>
#ifdef TKT_SHMEM
#include <sys/param.h>
#endif
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
extern int krb_debug;
/*
* in_tkt() is used to initialize the ticket store. It creates the
* file to contain the tickets and writes the given user's name "pname"
* and instance "pinst" in the file. in_tkt() returns KSUCCESS on
* success, or KFAILURE if something goes wrong.
*/
#ifdef HAVE_SETEUID
#define do_seteuid(e) seteuid((e))
#else
#ifdef HAVE_SETRESUID
#define do_seteuid(e) setresuid(-1, (e), -1)
#else
#ifdef HAVE_SETREUID
#define do_seteuid(e) setreuid(geteuid(), (e))
#else
#define do_seteuid(e) (errno = EPERM, -1)
#endif
#endif
#endif
#ifndef O_SYNC
#define O_SYNC 0
#endif
KRB5_DLLIMP int KRB5_CALLCONV
in_tkt(pname,pinst)
char *pname;
char *pinst;
{
int tktfile;
uid_t me, metoo, getuid(), geteuid();
struct stat statpre, statpost;
int count;
char *file = TKT_FILE;
int fd;
register int i;
char charbuf[BUFSIZ];
mode_t mask;
#ifdef TKT_SHMEM
char shmidname[MAXPATHLEN];
#endif /* TKT_SHMEM */
/* If ticket cache selector is null, use default cache. */
if (file == 0)
file = tkt_string();
me = getuid ();
metoo = geteuid();
if (lstat(file, &statpre) == 0) {
if (statpre.st_uid != me || !(statpre.st_mode & S_IFREG)
|| statpre.st_nlink != 1 || statpre.st_mode & 077) {
if (krb_debug)
fprintf(stderr,"Error initializing %s",file);
return(KFAILURE);
}
/*
* Yes, we do uid twiddling here. It's not optimal, but some
* applications may expect that the ruid is what should really
* own the ticket file, e.g. setuid applications.
*/
if (me != metoo && do_seteuid(me) < 0)
return KFAILURE;
/* file already exists, and permissions appear ok, so nuke it */
fd = open(file, O_RDWR|O_SYNC, 0);
(void)unlink(file);
if (me != metoo && do_seteuid(metoo) < 0)
return KFAILURE;
if (fd < 0) {
goto out; /* can't zero it, but we can still try truncating it */
}
/*
* Do some additional paranoid things. The worst-case
* situation is that a user may be fooled into opening a
* non-regular file briefly if the file is in a directory with
* improper permissions.
*/
if (fstat(fd, &statpost) < 0) {
(void)close(fd);
goto out;
}
if (statpre.st_dev != statpost.st_dev
|| statpre.st_ino != statpost.st_ino) {
(void)close(fd);
errno = 0;
goto out;
}
memset(charbuf, 0, sizeof(charbuf));
for (i = 0; i < statpost.st_size; i += sizeof(charbuf))
if (write(fd, charbuf, sizeof(charbuf)) != sizeof(charbuf)) {
#ifndef NO_FSYNC
(void) fsync(fd);
#endif
(void) close(fd);
goto out;
}
#ifndef NO_FSYNC
(void) fsync(fd);
#endif
(void) close(fd);
}
out:
/* arrange so the file is owned by the ruid
(swap real & effective uid if necessary).
This isn't a security problem, since the ticket file, if it already
exists, has the right uid (== ruid) and mode. */
if (me != metoo) {
if (do_seteuid(me) < 0) {
/* can't switch??? barf! */
if (krb_debug)
perror("in_tkt: seteuid");
return(KFAILURE);
} else
if (krb_debug)
printf("swapped UID's %d and %d\n",(int) metoo, (int) me);
}
/* Set umask to ensure that we have write access on the created
ticket file. */
mask = umask(077);
tktfile = open(file, O_RDWR|O_SYNC|O_CREAT|O_EXCL, 0600);
umask(mask);
if (me != metoo) {
if (do_seteuid(metoo) < 0) {
/* can't switch??? barf! */
if (krb_debug)
perror("in_tkt: seteuid2");
return(KFAILURE);
} else
if (krb_debug)
printf("swapped UID's %d and %d\n", (int) me, (int) metoo);
}
if (tktfile < 0) {
if (krb_debug)
fprintf(stderr,"Error initializing %s",TKT_FILE);
return(KFAILURE);
}
count = strlen(pname)+1;
if (write(tktfile,pname,count) != count) {
(void) close(tktfile);
return(KFAILURE);
}
count = strlen(pinst)+1;
if (write(tktfile,pinst,count) != count) {
(void) close(tktfile);
return(KFAILURE);
}
(void) close(tktfile);
#ifdef TKT_SHMEM
(void) strncpy(shmidname, file, sizeof(shmidname) - 1);
shmidname[sizeof(shmidname) - 1] = '\0';
(void) strncat(shmidname, ".shm", sizeof(shmidname) - 1 - strlen(shmidname));
return(krb_shm_create(shmidname));
#else /* !TKT_SHMEM */
return(KSUCCESS);
#endif /* TKT_SHMEM */
}
KRB5_DLLIMP int KRB5_CALLCONV
krb_in_tkt(pname, pinst, prealm)
char *pname;
char *pinst;
char *prealm;
{
return in_tkt(pname, pinst);
}
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