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/*
* lib/krb5/krb/rd_safe.c
*
* Copyright 1990,1991 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.
*
*
* krb5_rd_safe()
*/
#include "k5-int.h"
#include "cleanup.h"
#include "auth_con.h"
#define in_clock_skew(date) (labs((date)-currenttime) < context->clockskew)
/*
parses a KRB_SAFE message from inbuf, placing the integrity-protected user
data in *outbuf.
key specifies the key to be used for decryption of the message.
sender_addr and recv_addr specify the full addresses (host and port) of
the sender and receiver.
outbuf points to allocated storage which the caller should free when finished.
returns system errors, integrity errors
*/
static krb5_error_code
krb5_rd_safe_basic(krb5_context context, const krb5_data *inbuf, const krb5_keyblock *keyblock, const krb5_address *recv_addr, const krb5_address *sender_addr, krb5_replay_data *replaydata, krb5_data *outbuf)
{
krb5_error_code retval;
krb5_safe * message;
krb5_data safe_body;
krb5_checksum our_cksum, *his_cksum;
krb5_octet zero_octet = 0;
krb5_data *scratch;
krb5_boolean valid;
if (!krb5_is_krb_safe(inbuf))
return KRB5KRB_AP_ERR_MSG_TYPE;
if ((retval = decode_krb5_safe_with_body(inbuf, &message, &safe_body)))
return retval;
if (!krb5_c_valid_cksumtype(message->checksum->checksum_type)) {
retval = KRB5_PROG_SUMTYPE_NOSUPP;
goto cleanup;
}
if (!krb5_c_is_coll_proof_cksum(message->checksum->checksum_type) ||
!krb5_c_is_keyed_cksum(message->checksum->checksum_type)) {
retval = KRB5KRB_AP_ERR_INAPP_CKSUM;
goto cleanup;
}
if (!krb5_address_compare(context, sender_addr, message->s_address)) {
retval = KRB5KRB_AP_ERR_BADADDR;
goto cleanup;
}
if (message->r_address) {
if (recv_addr) {
if (!krb5_address_compare(context, recv_addr, message->r_address)) {
retval = KRB5KRB_AP_ERR_BADADDR;
goto cleanup;
}
} else {
krb5_address **our_addrs;
if ((retval = krb5_os_localaddr(context, &our_addrs)))
goto cleanup;
if (!krb5_address_search(context, message->r_address, our_addrs)) {
krb5_free_addresses(context, our_addrs);
retval = KRB5KRB_AP_ERR_BADADDR;
goto cleanup;
}
krb5_free_addresses(context, our_addrs);
}
}
/* verify the checksum */
/*
* In order to recreate what was checksummed, we regenerate the message
* without checksum and then have the cryptographic subsystem verify
* the checksum for us. This is because some checksum methods have
* a confounder encrypted as part of the checksum.
*/
his_cksum = message->checksum;
our_cksum.length = 0;
our_cksum.checksum_type = 0;
our_cksum.contents = &zero_octet;
message->checksum = &our_cksum;
if ((retval = encode_krb5_safe_with_body(message, &safe_body, &scratch)))
goto cleanup;
message->checksum = his_cksum;
retval = krb5_c_verify_checksum(context, keyblock,
KRB5_KEYUSAGE_KRB_SAFE_CKSUM,
scratch, his_cksum, &valid);
(void) memset((char *)scratch->data, 0, scratch->length);
krb5_free_data(context, scratch);
if (!valid) {
/*
* Checksum over only the KRB-SAFE-BODY, like RFC 1510 says, in
* case someone actually implements it correctly.
*/
retval = krb5_c_verify_checksum(context, keyblock,
KRB5_KEYUSAGE_KRB_SAFE_CKSUM,
&safe_body, his_cksum, &valid);
if (!valid) {
retval = KRB5KRB_AP_ERR_MODIFIED;
goto cleanup;
}
}
replaydata->timestamp = message->timestamp;
replaydata->usec = message->usec;
replaydata->seq = message->seq_number;
*outbuf = message->user_data;
message->user_data.data = NULL;
retval = 0;
cleanup:
krb5_free_safe(context, message);
return retval;
}
krb5_error_code KRB5_CALLCONV
krb5_rd_safe(krb5_context context, krb5_auth_context auth_context, const krb5_data *inbuf, krb5_data *outbuf, krb5_replay_data *outdata)
{
krb5_error_code retval;
krb5_keyblock * keyblock;
krb5_replay_data replaydata;
if (((auth_context->auth_context_flags & KRB5_AUTH_CONTEXT_RET_TIME) ||
(auth_context->auth_context_flags & KRB5_AUTH_CONTEXT_RET_SEQUENCE)) &&
(outdata == NULL))
/* Need a better error */
return KRB5_RC_REQUIRED;
if ((auth_context->auth_context_flags & KRB5_AUTH_CONTEXT_DO_TIME) &&
(auth_context->rcache == NULL))
return KRB5_RC_REQUIRED;
/* Get keyblock */
if ((keyblock = auth_context->recv_subkey) == NULL)
keyblock = auth_context->keyblock;
{
krb5_address * premote_fulladdr = NULL;
krb5_address * plocal_fulladdr = NULL;
krb5_address remote_fulladdr;
krb5_address local_fulladdr;
CLEANUP_INIT(2);
if (auth_context->local_addr) {
if (auth_context->local_port) {
if (!(retval = krb5_make_fulladdr(context, auth_context->local_addr,
auth_context->local_port,
&local_fulladdr))){
CLEANUP_PUSH(local_fulladdr.contents, free);
plocal_fulladdr = &local_fulladdr;
} else {
return retval;
}
} else {
plocal_fulladdr = auth_context->local_addr;
}
}
if (auth_context->remote_addr) {
if (auth_context->remote_port) {
if (!(retval = krb5_make_fulladdr(context,auth_context->remote_addr,
auth_context->remote_port,
&remote_fulladdr))){
CLEANUP_PUSH(remote_fulladdr.contents, free);
premote_fulladdr = &remote_fulladdr;
} else {
return retval;
}
} else {
premote_fulladdr = auth_context->remote_addr;
}
}
if ((retval = krb5_rd_safe_basic(context, inbuf, keyblock,
plocal_fulladdr, premote_fulladdr,
&replaydata, outbuf))) {
CLEANUP_DONE();
return retval;
}
CLEANUP_DONE();
}
if (auth_context->auth_context_flags & KRB5_AUTH_CONTEXT_DO_TIME) {
krb5_donot_replay replay;
krb5_timestamp currenttime;
if ((retval = krb5_timeofday(context, ¤ttime)))
goto error;
if (!in_clock_skew(replaydata.timestamp)) {
retval = KRB5KRB_AP_ERR_SKEW;
goto error;
}
if ((retval = krb5_gen_replay_name(context, auth_context->remote_addr,
"_safe", &replay.client)))
goto error;
replay.server = ""; /* XXX */
replay.cusec = replaydata.usec;
replay.ctime = replaydata.timestamp;
if ((retval = krb5_rc_store(context, auth_context->rcache, &replay))) {
krb5_xfree(replay.client);
goto error;
}
krb5_xfree(replay.client);
}
if (auth_context->auth_context_flags & KRB5_AUTH_CONTEXT_DO_SEQUENCE) {
if (!krb5int_auth_con_chkseqnum(context, auth_context,
replaydata.seq)) {
retval = KRB5KRB_AP_ERR_BADORDER;
goto error;
}
auth_context->remote_seq_number++;
}
if ((auth_context->auth_context_flags & KRB5_AUTH_CONTEXT_RET_TIME) ||
(auth_context->auth_context_flags & KRB5_AUTH_CONTEXT_RET_SEQUENCE)) {
outdata->timestamp = replaydata.timestamp;
outdata->usec = replaydata.usec;
outdata->seq = replaydata.seq;
}
/* everything is ok - return data to the user */
return 0;
error:
krb5_xfree(outbuf->data);
return retval;
}
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