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/*
* Copyright 1988 by the Massachusetts Institute of Technology.
* For copying and distribution information, please see the file
* <Copyright.MIT>.
*
* Shared memory segment functions for session keys. Derived from code
* contributed by Dan Kolkowitz (kolk@jessica.stanford.edu).
*
* from: tf_shm.c,v 4.2 89/10/25 23:26:46 qjb Exp $
* $Id: tf_shm.c,v 1.3 1995/07/18 16:39:48 mark Exp $
*/
#if 0
#ifndef lint
static char rcsid[] =
"$Id: tf_shm.c,v 1.3 1995/07/18 16:39:48 mark Exp $";
#endif lint
#endif
#include <stdio.h>
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/shm.h>
#include <krb.h>
#include <des.h>
#include <sys/stat.h>
#include <fcntl.h>
#define MAX_BUFF sizeof(des_cblock)*1000 /* room for 1k keys */
extern int errno;
extern int krb_debug;
/*
* krb_create_shmtkt:
*
* create a shared memory segment for session keys, leaving its id
* in the specified filename.
*/
int
krb_shm_create(file_name)
char *file_name;
{
int retval;
int shmid;
struct shmid_ds shm_buf;
FILE *sfile;
uid_t me, metoo, getuid(), geteuid();
(void) krb_shm_dest(file_name); /* nuke it if it exists...
this cleans up to make sure we
don't slowly lose memory. */
shmid = shmget((long)IPC_PRIVATE,MAX_BUFF, IPC_CREAT);
if (shmid == -1) {
if (krb_debug)
perror("krb_shm_create shmget");
return(KFAILURE); /* XXX */
}
me = getuid();
metoo = geteuid();
/*
* now set up the buffer so that we can modify it
*/
shm_buf.shm_perm.uid = me;
shm_buf.shm_perm.gid = getgid();
shm_buf.shm_perm.mode = 0600;
if (shmctl(shmid,IPC_SET,&shm_buf) < 0) { /*can now map it */
if (krb_debug)
perror("krb_shm_create shmctl");
(void) shmctl(shmid, IPC_RMID, 0);
return(KFAILURE); /* XXX */
}
(void) shmctl(shmid, SHM_LOCK, 0); /* attempt to lock-in-core */
/* arrange so the file is owned by the ruid
(swap real & effective uid if necessary). */
if (me != metoo) {
if (setreuid(metoo, me) < 0) {
/* can't switch??? barf! */
if (krb_debug)
perror("krb_shm_create: setreuid");
(void) shmctl(shmid, IPC_RMID, 0);
return(KFAILURE);
} else
if (krb_debug)
printf("swapped UID's %d and %d\n",metoo,me);
}
if ((sfile = fopen(file_name,"w")) == 0) {
if (krb_debug)
perror("krb_shm_create file");
(void) shmctl(shmid, IPC_RMID, 0);
return(KFAILURE); /* XXX */
}
if (fchmod(fileno(sfile),0600) < 0) {
if (krb_debug)
perror("krb_shm_create fchmod");
(void) shmctl(shmid, IPC_RMID, 0);
return(KFAILURE); /* XXX */
}
if (me != metoo) {
if (setreuid(me, metoo) < 0) {
/* can't switch??? barf! */
if (krb_debug)
perror("krb_shm_create: setreuid2");
(void) shmctl(shmid, IPC_RMID, 0);
return(KFAILURE);
} else
if (krb_debug)
printf("swapped UID's %d and %d\n",me,metoo);
}
(void) fprintf(sfile,"%d",shmid);
(void) fflush(sfile);
(void) fclose(sfile);
return(KSUCCESS);
}
/*
* krb_is_diskless:
*
* check / to see if file .diskless exists. If so it is diskless.
* Do it this way now to avoid dependencies on a particular routine.
* Choose root file system since that will be private to the client.
*/
int krb_is_diskless()
{
struct stat buf;
if (stat("/.diskless",&buf) < 0)
return(0);
else return(1);
}
/*
* krb_shm_dest: destroy shared memory segment with session keys, and remove
* file pointing to it.
*/
int krb_shm_dest(file)
char *file;
{
int shmid;
FILE *sfile;
struct stat st_buf;
if (stat(file,&st_buf) == 0) {
/* successful stat */
if ((sfile = fopen(file,"r")) == 0) {
if (krb_debug)
perror("cannot open shared memory file");
return(KFAILURE); /* XXX */
}
if (fscanf(sfile,"%d",&shmid) == 1) {
if (shmctl(shmid,IPC_RMID,0) != 0) {
if (krb_debug)
perror("krb_shm_dest: cannot delete shm segment");
(void) fclose(sfile);
return(KFAILURE); /* XXX */
}
} else {
if (krb_debug)
fprintf(stderr, "bad format in shmid file\n");
(void) fclose(sfile);
return(KFAILURE); /* XXX */
}
(void) fclose(sfile);
(void) unlink(file);
return(KSUCCESS);
} else
return(RET_TKFIL); /* XXX */
}
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