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Annotation of 43BSDReno/kerberosIV/krb/tf_shm.c, revision 1.1

1.1     ! root        1: /*
        !             2:  * $Source: /usr/src/kerberosIV/krb/RCS/tf_shm.c,v $
        !             3:  * $Author: kfall $
        !             4:  *
        !             5:  * Copyright 1988 by the Massachusetts Institute of Technology.
        !             6:  *
        !             7:  * For copying and distribution information, please see the file
        !             8:  * <mit-copyright.h>.
        !             9:  *
        !            10:  * Shared memory segment functions for session keys.  Derived from code
        !            11:  * contributed by Dan Kolkowitz ([email protected]).
        !            12:  */
        !            13: 
        !            14: #ifndef        lint
        !            15: static char rcsid_tf_shm_c[] =
        !            16: "$Id: tf_shm.c,v 4.3 90/06/25 20:57:30 kfall Exp $";
        !            17: #endif lint
        !            18: 
        !            19: #include <mit-copyright.h>
        !            20: 
        !            21: #include <stdio.h>
        !            22: #include <sys/types.h>
        !            23: #include <sys/ipc.h>
        !            24: #include <sys/shm.h>
        !            25: #include <des.h>
        !            26: #include <krb.h>
        !            27: #include <sys/stat.h>
        !            28: #include <fcntl.h>
        !            29: 
        !            30: #define MAX_BUFF sizeof(des_cblock)*1000 /* room for 1k keys */
        !            31: 
        !            32: extern int errno;
        !            33: extern int krb_debug;
        !            34: 
        !            35: /*
        !            36:  * krb_create_shmtkt:
        !            37:  *
        !            38:  * create a shared memory segment for session keys, leaving its id
        !            39:  * in the specified filename.
        !            40:  */
        !            41: 
        !            42: int
        !            43: krb_shm_create(file_name)
        !            44: char *file_name;
        !            45: {
        !            46:     int retval;
        !            47:     int shmid;
        !            48:     struct shmid_ds shm_buf;
        !            49:     FILE *sfile;
        !            50:     uid_t me, metoo, getuid(), geteuid();
        !            51: 
        !            52:     (void) krb_shm_dest(file_name);    /* nuke it if it exists...
        !            53:                                         this cleans up to make sure we
        !            54:                                         don't slowly lose memory. */
        !            55: 
        !            56:     shmid = shmget((long)IPC_PRIVATE,MAX_BUFF, IPC_CREAT);
        !            57:     if (shmid == -1) { 
        !            58:        if (krb_debug)
        !            59:            perror("krb_shm_create shmget");
        !            60:        return(KFAILURE);               /* XXX */
        !            61:     }
        !            62:     me = getuid();
        !            63:     metoo = geteuid();
        !            64:     /* 
        !            65:      * now set up the buffer so that we can modify it 
        !            66:      */
        !            67:     shm_buf.shm_perm.uid = me;
        !            68:     shm_buf.shm_perm.gid = getgid();
        !            69:     shm_buf.shm_perm.mode = 0600;
        !            70:     if (shmctl(shmid,IPC_SET,&shm_buf) < 0) { /*can now map it */
        !            71:        if (krb_debug)
        !            72:            perror("krb_shm_create shmctl");
        !            73:        (void) shmctl(shmid, IPC_RMID, 0);
        !            74:        return(KFAILURE);               /* XXX */
        !            75:     }
        !            76:     (void) shmctl(shmid, SHM_LOCK, 0); /* attempt to lock-in-core */
        !            77:     /* arrange so the file is owned by the ruid
        !            78:        (swap real & effective uid if necessary). */
        !            79:     if (me != metoo) {
        !            80:        if (setreuid(metoo, me) < 0) {
        !            81:            /* can't switch??? barf! */
        !            82:            if (krb_debug)
        !            83:                perror("krb_shm_create: setreuid");
        !            84:            (void) shmctl(shmid, IPC_RMID, 0);
        !            85:            return(KFAILURE);
        !            86:        } else
        !            87:            if (krb_debug)
        !            88:                printf("swapped UID's %d and %d\n",metoo,me);
        !            89:     }
        !            90:     if ((sfile = fopen(file_name,"w")) == 0) {
        !            91:        if (krb_debug)
        !            92:            perror("krb_shm_create file");
        !            93:        (void) shmctl(shmid, IPC_RMID, 0);
        !            94:        return(KFAILURE);               /* XXX */
        !            95:     } 
        !            96:     if (fchmod(fileno(sfile),0600) < 0) {
        !            97:        if (krb_debug)
        !            98:            perror("krb_shm_create fchmod");
        !            99:        (void) shmctl(shmid, IPC_RMID, 0);
        !           100:        return(KFAILURE);               /* XXX */
        !           101:     }  
        !           102:     if (me != metoo) {
        !           103:        if (setreuid(me, metoo) < 0) {
        !           104:            /* can't switch??? barf! */
        !           105:            if (krb_debug)
        !           106:                perror("krb_shm_create: setreuid2");
        !           107:            (void) shmctl(shmid, IPC_RMID, 0);
        !           108:            return(KFAILURE);
        !           109:        } else
        !           110:            if (krb_debug)
        !           111:                printf("swapped UID's %d and %d\n",me,metoo);
        !           112:     }
        !           113: 
        !           114:     (void) fprintf(sfile,"%d",shmid);
        !           115:     (void) fflush(sfile);
        !           116:     (void) fclose(sfile);
        !           117:     return(KSUCCESS);
        !           118: }
        !           119: 
        !           120: 
        !           121: /*
        !           122:  * krb_is_diskless:
        !           123:  *
        !           124:  * check / to see if file .diskless exists.  If so it is diskless.
        !           125:  *     Do it this way now to avoid dependencies on a particular routine.
        !           126:  *      Choose root file system since that will be private to the client.
        !           127:  */
        !           128: 
        !           129: int krb_is_diskless()
        !           130: {
        !           131:        struct stat buf;
        !           132:        if (stat("/.diskless",&buf) < 0) 
        !           133:                return(0);
        !           134:        else return(1);
        !           135: }
        !           136:                        
        !           137: /*
        !           138:  * krb_shm_dest: destroy shared memory segment with session keys, and remove
        !           139:  * file pointing to it.
        !           140:  */
        !           141: 
        !           142: int krb_shm_dest(file)
        !           143: char *file;
        !           144: {
        !           145:     int shmid;
        !           146:     FILE *sfile;
        !           147:     struct stat st_buf;
        !           148: 
        !           149:     if (stat(file,&st_buf) == 0) {
        !           150:        /* successful stat */
        !           151:        if ((sfile = fopen(file,"r")) == 0) {
        !           152:            if (krb_debug)
        !           153:                perror("cannot open shared memory file");
        !           154:            return(KFAILURE);           /* XXX */
        !           155:        }
        !           156:        if (fscanf(sfile,"%d",&shmid) == 1) {
        !           157:                if (shmctl(shmid,IPC_RMID,0) != 0) {
        !           158:                    if (krb_debug)
        !           159:                        perror("krb_shm_dest: cannot delete shm segment");
        !           160:                    (void) fclose(sfile);
        !           161:                    return(KFAILURE);   /* XXX */
        !           162:                }                   
        !           163:        } else {
        !           164:            if (krb_debug)
        !           165:                fprintf(stderr, "bad format in shmid file\n");
        !           166:            (void) fclose(sfile);
        !           167:            return(KFAILURE);           /* XXX */
        !           168:        }
        !           169:        (void) fclose(sfile);
        !           170:        (void) unlink(file);
        !           171:        return(KSUCCESS);
        !           172:     } else
        !           173:        return(RET_TKFIL);              /* XXX */
        !           174: }
        !           175: 
        !           176:        
        !           177: 

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