/* * rd_req.c * * Copyright 1985, 1986, 1987, 1988 by the Massachusetts Institute * of Technology. * * For copying and distribution information, please see the file * . */ #include "mit-copyright.h" #include "des.h" #include "krb.h" #include "prot.h" #include extern int krb_ap_req_debug; /* declared in krb.h */ int krb_ignore_ip_address = 0; /* * Keep the following information around for subsequent calls * to this routine by the same server using the same key. */ static Key_schedule serv_key; /* Key sched to decrypt ticket */ static C_Block ky; /* Initialization vector */ static int st_kvno; /* version number for this key */ static char st_rlm[REALM_SZ]; /* server's realm */ static char st_nam[ANAME_SZ]; /* service name */ static char st_inst[INST_SZ]; /* server's instance */ /* * This file contains two functions. krb_set_key() takes a DES * key or password string and returns a DES key (either the original * key, or the password converted into a DES key) and a key schedule * for it. * * krb_rd_req() reads an authentication request and returns information * about the identity of the requestor, or an indication that the * identity information was not authentic. */ /* * krb_set_key() takes as its first argument either a DES key or a * password string. The "cvt" argument indicates how the first * argument "key" is to be interpreted: if "cvt" is null, "key" is * taken to be a DES key; if "cvt" is non-null, "key" is taken to * be a password string, and is converted into a DES key using * string_to_key(). In either case, the resulting key is returned * in the external static variable "ky". A key schedule is * generated for "ky" and returned in the external static variable * "serv_key". * * This routine returns the return value of des_key_sched. * * krb_set_key() needs to be in the same .o file as krb_rd_req() so that * the key set by krb_set_key() is available in private storage for * krb_rd_req(). */ int krb_set_key(key,cvt) char *key; int cvt; { #ifdef NOENCRYPTION memset(ky, 0, sizeof(ky)); return KSUCCESS; #else /* Encrypt */ if (cvt) string_to_key(key,ky); else memcpy((char *)ky, key, 8); return(des_key_sched(ky,serv_key)); #endif /* NOENCRYPTION */ } /* * krb_rd_req() takes an AUTH_MSG_APPL_REQUEST or * AUTH_MSG_APPL_REQUEST_MUTUAL message created by krb_mk_req(), * checks its integrity and returns a judgement as to the requestor's * identity. * * The "authent" argument is a pointer to the received message. * The "service" and "instance" arguments name the receiving server, * and are used to get the service's ticket to decrypt the ticket * in the message, and to compare against the server name inside the * ticket. "from_addr" is the network address of the host from which * the message was received; this is checked against the network * address in the ticket. If "from_addr" is zero, the check is not * performed. "ad" is an AUTH_DAT structure which is * filled in with information about the sender's identity according * to the authenticator and ticket sent in the message. Finally, * "fn" contains the name of the file containing the server's key. * (If "fn" is NULL, the server's key is assumed to have been set * by krb_set_key(). If "fn" is the null string ("") the default * file KEYFILE, defined in "krb.h", is used.) * * krb_rd_req() returns RD_AP_OK if the authentication information * was genuine, or one of the following error codes (defined in * "krb.h"): * * RD_AP_VERSION - wrong protocol version number * RD_AP_MSG_TYPE - wrong message type * RD_AP_UNDEC - couldn't decipher the message * RD_AP_INCON - inconsistencies found * RD_AP_BADD - wrong network address * RD_AP_TIME - client time (in authenticator) * too far off server time * RD_AP_NYV - Kerberos time (in ticket) too * far off server time * RD_AP_EXP - ticket expired * * For the message format, see krb_mk_req(). * * Mutual authentication is not implemented. */ int INTERFACE krb_rd_req(authent,service,instance,from_addr,ad,fn) register KTEXT authent; /* The received message */ char *service; /* Service name */ char *instance; /* Service instance */ unsigned KRB4_32 from_addr; /* Net address of originating host */ AUTH_DAT *ad; /* Structure to be filled in */ char *fn; /* Filename to get keys from */ { KTEXT_ST ticket; /* Temp storage for ticket */ KTEXT tkt = &ticket; KTEXT_ST req_id_st; /* Temp storage for authenticator */ register KTEXT req_id = &req_id_st; char realm[REALM_SZ]; /* Realm of issuing kerberos */ Key_schedule seskey_sched; /* Key sched for session key */ unsigned char skey[KKEY_SZ]; /* Session key from ticket */ char sname[SNAME_SZ]; /* Service name from ticket */ char iname[INST_SZ]; /* Instance name from ticket */ char r_aname[ANAME_SZ]; /* Client name from authenticator */ char r_inst[INST_SZ]; /* Client instance from authenticator */ char r_realm[REALM_SZ]; /* Client realm from authenticator */ unsigned int r_time_ms; /* Fine time from authenticator */ unsigned KRB4_32 r_time_sec; /* Coarse time from authenticator */ register char *ptr; /* For stepping through */ unsigned KRB4_32 t_local; /* Local time on our side of the protocol */ KRB4_32 delta_t; /* Time in authenticator minus local time */ KRB4_32 tkt_age; /* Age of ticket */ int swap_bytes; /* Need to swap bytes? */ int mutual; /* Mutual authentication requested? */ unsigned char s_kvno; /* Version number of the server's key Kerberos used to encrypt ticket */ int status; if (authent->length <= 0) return(RD_AP_MODIFIED); ptr = (char *) authent->dat; /* get msg version, type and byte order, and server key version */ /* check version */ if (KRB_PROT_VERSION != (unsigned int) *ptr++) return(RD_AP_VERSION); /* byte order */ swap_bytes = 0; if ((*ptr & 1) != HOST_BYTE_ORDER) swap_bytes++; /* check msg type */ mutual = 0; switch (*ptr++ & ~1) { case AUTH_MSG_APPL_REQUEST: break; case AUTH_MSG_APPL_REQUEST_MUTUAL: mutual++; break; default: return(RD_AP_MSG_TYPE); } #ifdef lint /* XXX mutual is set but not used; why??? */ /* this is a crock to get lint to shut up */ if (mutual) mutual = 0; #endif /* lint */ s_kvno = *ptr++; /* get server key version */ (void) strcpy(realm,ptr); /* And the realm of the issuing KDC */ ptr += strlen(ptr) + 1; /* skip the realm "hint" */ /* * If "fn" is NULL, key info should already be set; don't * bother with ticket file. Otherwise, check to see if we * already have key info for the given server and key version * (saved in the static st_* variables). If not, go get it * from the ticket file. If "fn" is the null string, use the * default ticket file. */ if (fn && (strcmp(st_nam,service) || strcmp(st_inst,instance) || strcmp(st_rlm,realm) || (st_kvno != s_kvno))) { if (*fn == 0) fn = KEYFILE; st_kvno = s_kvno; #ifndef NOENCRYPTION if (read_service_key(service,instance,realm,(int) s_kvno, fn,(char *)skey)) return(RD_AP_UNDEC); if (status = krb_set_key((char *)skey,0)) return(status); #endif /* !NOENCRYPTION */ (void) strcpy(st_rlm,realm); (void) strcpy(st_nam,service); (void) strcpy(st_inst,instance); } /* Get ticket from authenticator */ tkt->length = (int) *ptr++; if ((tkt->length + (ptr+1 - (char *) authent->dat)) > authent->length) return(RD_AP_MODIFIED); memcpy((char *)(tkt->dat), ptr+1, tkt->length); #ifdef KRB_CRYPT_DEBUG if (krb_ap_req_debug) log("ticket->length: %d",tkt->length); if (krb_ap_req_debug) log("authent->length: %d", authent->length); #endif #ifndef NOENCRYPTION /* Decrypt and take apart ticket */ #endif if (decomp_ticket(tkt,&ad->k_flags,ad->pname,ad->pinst,ad->prealm, &(ad->address),ad->session, &(ad->life), &(ad->time_sec),sname,iname,ky,serv_key)) { #ifdef KRB_CRYPT_DEBUG log("Can't decode ticket"); #endif return(RD_AP_UNDEC); } #ifdef KRB_CRYPT_DEBUG if (krb_ap_req_debug) { log("Ticket Contents."); log(" Aname: %s%s%s@%s",ad->pname, ((int)*(ad->pinst) ? "." : ""), ad->pinst, ((int)*(ad->prealm) ? ad->prealm : "Athena")); log(" Service: %s%s%s",sname,((int)*iname ? "." : ""),iname); log(" sname=%s, sinst=%s", sname, iname); } #endif /* Extract the authenticator */ req_id->length = (int) *(ptr++); if ((req_id->length + (ptr + tkt->length - (char *) authent->dat)) > authent->length) return(RD_AP_MODIFIED); memcpy((char *)(req_id->dat), ptr + tkt->length, req_id->length); #ifndef NOENCRYPTION /* And decrypt it with the session key from the ticket */ #ifdef KRB_CRYPT_DEBUG if (krb_ap_req_debug) log("About to decrypt authenticator"); #endif key_sched(ad->session,seskey_sched); pcbc_encrypt((C_Block *)req_id->dat,(C_Block *)req_id->dat, (long) req_id->length, seskey_sched,ad->session,DES_DECRYPT); #ifdef KRB_CRYPT_DEBUG if (krb_ap_req_debug) log("Done."); #endif #endif /* NOENCRYPTION */ #define check_ptr() if ((ptr - (char *) req_id->dat) > req_id->length) return(RD_AP_MODIFIED); ptr = (char *) req_id->dat; (void) strcpy(r_aname,ptr); /* Authentication name */ ptr += strlen(r_aname)+1; check_ptr(); (void) strcpy(r_inst,ptr); /* Authentication instance */ ptr += strlen(r_inst)+1; check_ptr(); (void) strcpy(r_realm,ptr); /* Authentication name */ ptr += strlen(r_realm)+1; check_ptr(); memcpy((char *)&ad->checksum, ptr, 4); /* Checksum */ ptr += 4; check_ptr(); if (swap_bytes) swap_u_long(ad->checksum); r_time_ms = *(ptr++); /* Time (fine) */ #ifdef lint /* XXX r_time_ms is set but not used. why??? */ /* this is a crock to get lint to shut up */ if (r_time_ms) r_time_ms = 0; #endif /* lint */ check_ptr(); /* assume sizeof(r_time_sec) == 4 ?? */ memcpy((char *)&r_time_sec, ptr, 4); /* Time (coarse) */ if (swap_bytes) swap_u_long(r_time_sec); /* Check for authenticity of the request */ #ifdef KRB_CRYPT_DEBUG if (krb_ap_req_debug) log("Pname: %s %s",ad->pname,r_aname); #endif if (strcmp(ad->pname,r_aname) != 0) return(RD_AP_INCON); if (strcmp(ad->pinst,r_inst) != 0) return(RD_AP_INCON); #ifdef KRB_CRYPT_DEBUG if (krb_ap_req_debug) log("Realm: %s %s",ad->prealm,r_realm); #endif if ((strcmp(ad->prealm,r_realm) != 0)) return(RD_AP_INCON); /* check the time integrity of the msg */ t_local = TIME_GMT_UNIXSEC; delta_t = t_local - r_time_sec; if (delta_t < 0) delta_t = -delta_t; /* Absolute value of difference */ if (delta_t > CLOCK_SKEW) { #ifdef KRB_CRYPT_DEBUG if (krb_ap_req_debug) log("Time out of range: %d - %d = %d", time_secs, r_time_sec, delta_t); #endif return(RD_AP_TIME); } /* Now check for expiration of ticket */ tkt_age = t_local - ad->time_sec; #ifdef KRB_CRYPT_DEBUG if (krb_ap_req_debug) log("Time: %d Issue Date: %d Diff: %d Life %x", time_secs, ad->time_sec, tkt_age, ad->life); #endif if (t_local < ad->time_sec) { if ((ad->time_sec - t_local) > CLOCK_SKEW) return(RD_AP_NYV); } else if ((t_local - ad->time_sec) > 5 * 60 * ad->life) return(RD_AP_EXP); #ifdef KRB_CRYPT_DEBUG if (krb_ap_req_debug) log("Address: %d %d",ad->address,from_addr); #endif if (!krb_ignore_ip_address && from_addr && (ad->address != from_addr)) return(RD_AP_BADD); /* All seems OK */ ad->reply.length = 0; return(RD_AP_OK); }