/*
* radius.c Functions to send/receive radius packets.
*
* Version: $Id: radius.c,v 1.125.2.5.2.10 2007/02/13 09:37:12 aland Exp $
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
*
* Copyright 2000-2003 The FreeRADIUS server project
*/
static const char rcsid[] = "$Id: radius.c,v 1.125.2.5.2.10 2007/02/13 09:37:12 aland Exp $";
#include "autoconf.h"
#include "md5.h"
#include <stdlib.h>
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#include <fcntl.h>
#include <string.h>
#include <ctype.h>
#include "libradius.h"
#ifdef WITH_UDPFROMTO
#include "udpfromto.h"
#endif
#ifdef HAVE_NETINET_IN_H
#include <netinet/in.h>
#endif
#include <sys/socket.h>
#ifdef HAVE_ARPA_INET_H
#include <arpa/inet.h>
#endif
#ifdef HAVE_MALLOC_H
#include <malloc.h>
#endif
#ifdef WIN32
#include <process.h>
#endif
/*
* The RFC says 4096 octets max, and most packets are less than 256.
*/
#define MAX_PACKET_LEN 4096
/*
* The maximum number of attributes which we allow in an incoming
* request. If there are more attributes than this, the request
* is rejected.
*
* This helps to minimize the potential for a DoS, when an
* attacker spoofs Access-Request packets, which don't have a
* Message-Authenticator attribute. This means that the packet
* is unsigned, and the attacker can use resources on the server,
* even if the end request is rejected.
*/
int librad_max_attributes = 0;
typedef struct radius_packet_t {
uint8_t code;
uint8_t id;
uint8_t length[2];
uint8_t vector[AUTH_VECTOR_LEN];
uint8_t data[1];
} radius_packet_t;
static lrad_randctx lrad_rand_pool; /* across multiple calls */
static volatile int lrad_rand_index = -1;
static unsigned int salt_offset = 0;
static const char *packet_codes[] = {
"",
"Access-Request",
"Access-Accept",
"Access-Reject",
"Accounting-Request",
"Accounting-Response",
"Accounting-Status",
"Password-Request",
"Password-Accept",
"Password-Reject",
"Accounting-Message",
"Access-Challenge",
"Status-Server",
"Status-Client",
"14",
"15",
"16",
"17",
"18",
"19",
"20",
"Resource-Free-Request",
"Resource-Free-Response",
"Resource-Query-Request",
"Resource-Query-Response",
"Alternate-Resource-Reclaim-Request",
"NAS-Reboot-Request",
"NAS-Reboot-Response",
"28",
"Next-Passcode",
"New-Pin",
"Terminate-Session",
"Password-Expired",
"Event-Request",
"Event-Response",
"35",
"36",
"37",
"38",
"39",
"Disconnect-Request",
"Disconnect-ACK",
"Disconnect-NAK",
"CoA-Request",
"CoA-ACK",
"CoA-NAK",
"46",
"47",
"48",
"49",
"IP-Address-Allocate",
"IP-Address-Release"
};
#define AUTH_PASS_LEN (AUTH_VECTOR_LEN)
/*************************************************************************
*
* Function: make_secret
*
* Purpose: Build an encrypted secret value to return in a reply
* packet. The secret is hidden by xoring with a MD5 digest
* created from the shared secret and the authentication
* vector. We put them into MD5 in the reverse order from
* that used when encrypting passwords to RADIUS.
*
*************************************************************************/
static void make_secret(uint8_t *digest, const uint8_t *vector,
const char *secret, const uint8_t *value)
{
MD5_CTX context;
int i;
MD5Init(&context);
MD5Update(&context, vector, AUTH_VECTOR_LEN);
MD5Update(&context, secret, strlen(secret));
MD5Final(digest, &context);
for ( i = 0; i < AUTH_VECTOR_LEN; i++ ) {
digest[i] ^= value[i];
}
}
#define MAX_PASS_LEN (128)
static void make_passwd(uint8_t *output, int *outlen,
const uint8_t *input, int inlen,
const char *secret, const uint8_t *vector)
{
MD5_CTX context, old;
uint8_t digest[AUTH_VECTOR_LEN];
uint8_t passwd[MAX_PASS_LEN];
int i, n;
int len;
/*
* If the length is zero, round it up.
*/
len = inlen;
if (len == 0) {
len = AUTH_PASS_LEN;
}
else if (len > MAX_PASS_LEN) len = MAX_PASS_LEN;
else if ((len & 0x0f) != 0) {
len += 0x0f;
len &= ~0x0f;
}
*outlen = len;
memcpy(passwd, input, len);
memset(passwd + len, 0, sizeof(passwd) - len);
MD5Init(&context);
MD5Update(&context, secret, strlen(secret));
old = context;
/*
* Do first pass.
*/
MD5Update(&context, vector, AUTH_PASS_LEN);
for (n = 0; n < len; n += AUTH_PASS_LEN) {
if (n > 0) {
context = old;
MD5Update(&context,
passwd + n - AUTH_PASS_LEN,
AUTH_PASS_LEN);
}
MD5Final(digest, &context);
for (i = 0; i < AUTH_PASS_LEN; i++) {
passwd[i + n] ^= digest[i];
}
}
memcpy(output, passwd, len);
}
static void make_tunnel_passwd(uint8_t *output, int *outlen,
const uint8_t *input, int inlen, int room,
const char *secret, const uint8_t *vector)
{
MD5_CTX context, old;
uint8_t digest[AUTH_VECTOR_LEN];
uint8_t passwd[MAX_STRING_LEN + AUTH_VECTOR_LEN];
int i, n;
int len;
/*
* Account for 2 bytes of the salt, and round the room
* available down to the nearest multiple of 16. Then,
* subtract one from that to account for the length byte,
* and the resulting number is the upper bound on the data
* to copy.
*
* We could short-cut this calculation just be forcing
* inlen to be no more than 239. It would work for all
* VSA's, as we don't pack multiple VSA's into one
* attribute.
*
* However, this calculation is more general, if a little
* complex. And it will work in the future for all possible
* kinds of weird attribute packing.
*/
room -= 2;
room -= (room & 0x0f);
room--;
if (inlen > room) inlen = room;
/*
* Length of the encrypted data is password length plus
* one byte for the length of the password.
*/
len = inlen + 1;
if ((len & 0x0f) != 0) {
len += 0x0f;
len &= ~0x0f;
}
*outlen = len + 2; /* account for the salt */
/*
* Copy the password over.
*/
memcpy(passwd + 3, input, inlen);
memset(passwd + 3 + inlen, 0, sizeof(passwd) - 3 - inlen);
/*
* Generate salt. The RFC's say:
*
* The high bit of salt[0] must be set, each salt in a
* packet should be unique, and they should be random
*
* So, we set the high bit, add in a counter, and then
* add in some CSPRNG data. should be OK..
*/
passwd[0] = (0x80 | ( ((salt_offset++) & 0x0f) << 3) |
(lrad_rand() & 0x07));
passwd[1] = lrad_rand();
passwd[2] = inlen; /* length of the password string */
MD5Init(&context);
MD5Update(&context, secret, strlen(secret));
old = context;
MD5Update(&context, vector, AUTH_VECTOR_LEN);
MD5Update(&context, &passwd[0], 2);
for (n = 0; n < len; n += AUTH_PASS_LEN) {
if (n > 0) {
context = old;
MD5Update(&context,
passwd + 2 + n - AUTH_PASS_LEN,
AUTH_PASS_LEN);
}
MD5Final(digest, &context);
for (i = 0; i < AUTH_PASS_LEN; i++) {
passwd[i + 2 + n] ^= digest[i];
}
}
memcpy(output, passwd, len + 2);
}
/*
* Parse a data structure into a RADIUS attribute.
*/
int rad_vp2attr(const RADIUS_PACKET *packet, const RADIUS_PACKET *original,
const char *secret, const VALUE_PAIR *vp, uint8_t *ptr)
{
int vendorcode;
int offset, len, total_length;
uint32_t lvalue;
uint8_t *length_ptr, *vsa_length_ptr;
const uint8_t *data = NULL;
uint8_t array[4];
vendorcode = total_length = 0;
length_ptr = vsa_length_ptr = NULL;
/*
* For interoperability, always put vendor attributes
* into their own VSA.
*/
if ((vendorcode = VENDOR(vp->attribute)) != 0) {
/*
* Build a VSA header.
*/
*ptr++ = PW_VENDOR_SPECIFIC;
vsa_length_ptr = ptr;
*ptr++ = 6;
lvalue = htonl(vendorcode);
memcpy(ptr, &lvalue, 4);
ptr += 4;
total_length += 6;
if (vendorcode == VENDORPEC_USR) {
lvalue = htonl(vp->attribute & 0xFFFF);
memcpy(ptr, &lvalue, 4);
length_ptr = vsa_length_ptr;
total_length += 4;
*length_ptr += 4;
ptr += 4;
/*
* We don't have two different lengths.
*/
vsa_length_ptr = NULL;
} else if (vendorcode == VENDORPEC_LUCENT) {
/*
* 16-bit attribute, 8-bit length
*/
*ptr++ = ((vp->attribute >> 8) & 0xFF);
*ptr++ = (vp->attribute & 0xFF);
length_ptr = ptr;
*vsa_length_ptr += 3;
*ptr++ = 3;
total_length += 3;
} else if (vendorcode == VENDORPEC_STARENT) {
/*
* 16-bit attribute, 16-bit length
* with the upper 8 bits of the length
* always zero!
*/
*ptr++ = ((vp->attribute >> 8) & 0xFF);
*ptr++ = (vp->attribute & 0xFF);
*ptr++ = 0;
length_ptr = ptr;
*vsa_length_ptr += 4;
*ptr++ = 4;
total_length += 4;
} else {
/*
* All other VSA's are encoded the same
* as RFC attributes.
*/
*vsa_length_ptr += 2;
goto rfc;
}
} else {
rfc:
/*
* All other attributes are encoded as
* per the RFC.
*/
*ptr++ = (vp->attribute & 0xFF);
length_ptr = ptr;
*ptr++ = 2;
total_length += 2;
}
offset = 0;
if (vp->flags.has_tag) {
if (TAG_VALID(vp->flags.tag)) {
ptr[0] = vp->flags.tag & 0xff;
offset = 1;
} else if (vp->flags.encrypt == FLAG_ENCRYPT_TUNNEL_PASSWORD) {
/*
* Tunnel passwords REQUIRE a tag, even
* if don't have a valid tag.
*/
ptr[0] = 0;
offset = 1;
} /* else don't write a tag */
} /* else the attribute doesn't have a tag */
/*
* Set up the default sources for the data.
*/
data = vp->strvalue;
len = vp->length;
/*
* Encrypted passwords can't be very long.
* This check also ensures that the hashed version
* of the password + attribute header fits into one
* attribute.
*
* FIXME: Print a warning message if it's too long?
*/
if (vp->flags.encrypt && (len > MAX_PASS_LEN)) {
len = MAX_PASS_LEN;
}
switch(vp->type) {
case PW_TYPE_STRING:
case PW_TYPE_OCTETS:
case PW_TYPE_IFID:
case PW_TYPE_IPV6ADDR:
case PW_TYPE_IPV6PREFIX:
case PW_TYPE_ABINARY:
/* nothing more to do */
break;
case PW_TYPE_INTEGER:
len = 4; /* just in case */
lvalue = htonl(vp->lvalue);
memcpy(array, &lvalue, sizeof(lvalue));
/*
* Perhaps discard the first octet.
*/
data = &array[offset];
len -= offset;
break;
case PW_TYPE_IPADDR:
data = (const uint8_t *) &vp->lvalue;
len = 4; /* just in case */
break;
/*
* There are no tagged date attributes.
*/
case PW_TYPE_DATE:
lvalue = htonl(vp->lvalue);
data = (const uint8_t *) &lvalue;
len = 4; /* just in case */
break;
default: /* unknown type: ignore it */
librad_log("ERROR: Unknown attribute type %d", vp->type);
return -1;
}
/*
* Bound the data to 255 bytes.
*/
if (len + offset + total_length > 255) {
len = 255 - offset - total_length;
}
/*
* Encrypt the various password styles
*
* Attributes with encrypted values MUST be less than
* 128 bytes long.
*/
switch (vp->flags.encrypt) {
case FLAG_ENCRYPT_USER_PASSWORD:
make_passwd(ptr + offset, &len,
data, len,
secret, packet->vector);
break;
case FLAG_ENCRYPT_TUNNEL_PASSWORD:
if (!original) {
librad_log("ERROR: No request packet, cannot encrypt %s attribute in the vp.", vp->name);
return -1;
}
/*
* Check if 255 - offset - total_length is less
* than 18. If so, we can't fit the data into
* the available space, and we discard the
* attribute.
*
* This is ONLY a problem if we have multiple VSA's
* in one Vendor-Specific, though.
*/
if ((255 - offset - total_length) < 18) return 0;
/*
* Can't make the password, suppress it.
*/
make_tunnel_passwd(ptr + offset, &len,
data, len, 255 - offset - total_length,
secret, original->vector);
break;
/*
* The code above ensures that this attribute
* always fits.
*/
case FLAG_ENCRYPT_ASCEND_SECRET:
make_secret(ptr + offset, packet->vector,
secret, data);
len = AUTH_VECTOR_LEN;
break;
default:
/*
* Just copy the data over
*/
memcpy(ptr + offset, data, len);
break;
} /* switch over encryption flags */
/*
* Account for the tag (if any).
*/
len += offset;
/*
* RFC 2865 section 5 says that zero-length attributes
* MUST NOT be sent.
*/
if (len == 0) return 0;
/*
* Update the various lengths.
*/
*length_ptr += len;
if (vsa_length_ptr) *vsa_length_ptr += len;
ptr += len;
total_length += len;
return total_length; /* of attribute */
}
/*
* Encode a packet.
*/
int rad_encode(RADIUS_PACKET *packet, const RADIUS_PACKET *original,
const char *secret)
{
radius_packet_t *hdr;
uint8_t *ptr;
uint16_t total_length;
int len;
VALUE_PAIR *reply;
/*
* For simplicity in the following logic, we allow
* the attributes to "overflow" the 4k maximum
* RADIUS packet size, by one attribute.
*
* It's uint32_t, for alignment purposes.
*/
uint32_t data[(MAX_PACKET_LEN + 256) / 4];
/*
* Double-check some things based on packet code.
*/
switch (packet->code) {
case PW_AUTHENTICATION_ACK:
case PW_AUTHENTICATION_REJECT:
case PW_ACCESS_CHALLENGE:
if (!original) {
librad_log("ERROR: Cannot sign response packet without a request packet.");
return -1;
}
break;
/*
* These packet vectors start off as all zero.
*/
case PW_ACCOUNTING_REQUEST:
case PW_DISCONNECT_REQUEST:
case PW_COA_REQUEST:
memset(packet->vector, 0, sizeof(packet->vector));
break;
default:
break;
}
/*
* Use memory on the stack, until we know how
* large the packet will be.
*/
hdr = (radius_packet_t *) data;
/*
* Build standard header
*/
hdr->code = packet->code;
hdr->id = packet->id;
memcpy(hdr->vector, packet->vector, sizeof(hdr->vector));
total_length = AUTH_HDR_LEN;
packet->verified = 0;
/*
* Load up the configuration values for the user
*/
ptr = hdr->data;
/*
* FIXME: Loop twice over the reply list. The first time,
* calculate the total length of data. The second time,
* allocate the memory, and fill in the VP's.
*
* Hmm... this may be slower than just doing a small
* memcpy.
*/
/*
* Loop over the reply attributes for the packet.
*/
for (reply = packet->vps; reply; reply = reply->next) {
/*
* Ignore non-wire attributes
*/
if ((VENDOR(reply->attribute) == 0) &&
((reply->attribute & 0xFFFF) > 0xff)) {
continue;
}
/*
* Set the Message-Authenticator to the correct
* length and initial value.
*/
if (reply->attribute == PW_MESSAGE_AUTHENTICATOR) {
reply->length = AUTH_VECTOR_LEN;
memset(reply->strvalue, 0, AUTH_VECTOR_LEN);
packet->verified = total_length; /* HACK! */
}
/*
* Print out ONLY the attributes which
* we're sending over the wire, and print
* them out BEFORE they're encrypted.
*/
debug_pair(reply);
len = rad_vp2attr(packet, original, secret, reply, ptr);
if (len < 0) return -1;
/*
* Check that the packet is no more than 4k in
* size, AFTER writing the attribute past the 4k
* boundary, but BEFORE deciding to increase the
* size of the packet. Note that the 'data'
* buffer, above, is one attribute longer than
* necessary, in order to permit this overflow.
*/
if ((total_length + len) > MAX_PACKET_LEN) {
break;
}
ptr += len;
total_length += len;
} /* done looping over all attributes */
/*
* Fill in the rest of the fields, and copy the data over
* from the local stack to the newly allocated memory.
*
* Yes, all this 'memcpy' is slow, but it means
* that we only allocate the minimum amount of
* memory for a request.
*/
packet->data_len = total_length;
packet->data = (uint8_t *) malloc(packet->data_len);
if (!packet->data) {
librad_log("Out of memory");
return -1;
}
memcpy(packet->data, data, packet->data_len);
hdr = (radius_packet_t *) packet->data;
total_length = htons(total_length);
memcpy(hdr->length, &total_length, sizeof(total_length));
return 0;
}
/*
* Sign a previously encoded packet.
*/
int rad_sign(RADIUS_PACKET *packet, const RADIUS_PACKET *original,
const char *secret)
{
radius_packet_t *hdr = (radius_packet_t *)packet->data;
/*
* It wasn't assigned an Id, this is bad!
*/
if (packet->id < 0) {
librad_log("ERROR: RADIUS packets must be assigned an Id.");
return -1;
}
if (!packet->data || (packet->data_len < AUTH_HDR_LEN) ||
(packet->verified < 0)) {
librad_log("ERROR: You must call rad_encode() before rad_sign()");
return -1;
}
/*
* If there's a Message-Authenticator, update it
* now, BEFORE updating the authentication vector.
*
* This is a hack...
*/
if (packet->verified > 0) {
uint8_t calc_auth_vector[AUTH_VECTOR_LEN];
switch (packet->code) {
case PW_ACCOUNTING_REQUEST:
case PW_ACCOUNTING_RESPONSE:
case PW_DISCONNECT_REQUEST:
case PW_DISCONNECT_ACK:
case PW_DISCONNECT_NAK:
case PW_COA_REQUEST:
case PW_COA_ACK:
case PW_COA_NAK:
memset(hdr->vector, 0, AUTH_VECTOR_LEN);
break;
case PW_AUTHENTICATION_ACK:
case PW_AUTHENTICATION_REJECT:
case PW_ACCESS_CHALLENGE:
if (!original) {
librad_log("ERROR: Cannot sign response packet without a request packet.");
return -1;
}
memcpy(hdr->vector, original->vector,
AUTH_VECTOR_LEN);
break;
default: /* others have vector already set to zero */
break;
}
/*
* Set the authentication vector to zero,
* calculate the signature, and put it
* into the Message-Authenticator
* attribute.
*/
lrad_hmac_md5(packet->data, packet->data_len,
secret, strlen(secret),
calc_auth_vector);
memcpy(packet->data + packet->verified + 2,
calc_auth_vector, AUTH_VECTOR_LEN);
/*
* Copy the original request vector back
* to the raw packet.
*/
memcpy(hdr->vector, packet->vector, AUTH_VECTOR_LEN);
}
/*
* Switch over the packet code, deciding how to
* sign the packet.
*/
switch (packet->code) {
/*
* Request packets are not signed, bur
* have a random authentication vector.
*/
case PW_AUTHENTICATION_REQUEST:
case PW_STATUS_SERVER:
break;
/*
* Reply packets are signed with the
* authentication vector of the request.
*/
default:
{
uint8_t digest[16];
MD5_CTX context;
MD5Init(&context);
MD5Update(&context, packet->data, packet->data_len);
MD5Update(&context, secret, strlen(secret));
MD5Final(digest, &context);
memcpy(hdr->vector, digest, AUTH_VECTOR_LEN);
memcpy(packet->vector, digest, AUTH_VECTOR_LEN);
break;
}
}/* switch over packet codes */
return 0;
}
/*
* Reply to the request. Also attach
* reply attribute value pairs and any user message provided.
*/
int rad_send(RADIUS_PACKET *packet, const RADIUS_PACKET *original,
const char *secret)
{
VALUE_PAIR *reply;
const char *what;
char ip_buffer[128];
struct sockaddr_in saremote;
struct sockaddr_in *sa;
/*
* Maybe it's a fake packet. Don't send it.
*/
if (!packet || (packet->sockfd < 0)) {
return 0;
}
if ((packet->code > 0) && (packet->code < 52)) {
what = packet_codes[packet->code];
} else {
what = "Reply";
}
/*
* First time through, allocate room for the packet
*/
if (!packet->data) {
DEBUG("Sending %s of id %d to %s port %d\n",
what, packet->id,
ip_ntoa(ip_buffer, packet->dst_ipaddr),
packet->dst_port);
/*
* Encode the packet.
*/
if (rad_encode(packet, original, secret) < 0) {
return -1;
}
/*
* Re-sign it, including updating the
* Message-Authenticator.
*/
if (rad_sign(packet, original, secret) < 0) {
return -1;
}
/*
* If packet->data points to data, then we print out
* the VP list again only for debugging.
*/
} else if (librad_debug) {
DEBUG("Re-sending %s of id %d to %s port %d\n", what, packet->id,
ip_ntoa(ip_buffer, packet->dst_ipaddr),
packet->dst_port);
for (reply = packet->vps; reply; reply = reply->next) {
/* FIXME: ignore attributes > 0xff */
debug_pair(reply);
}
}
/*
* And send it on it's way.
*/
sa = (struct sockaddr_in *) &saremote;
memset ((char *) sa, '\0', sizeof (saremote));
sa->sin_family = AF_INET;
sa->sin_addr.s_addr = packet->dst_ipaddr;
sa->sin_port = htons(packet->dst_port);
#ifndef WITH_UDPFROMTO
return sendto(packet->sockfd, packet->data, (int)packet->data_len, 0,
(struct sockaddr *)&saremote, sizeof(struct sockaddr_in));
#else
{
struct sockaddr_in salocal;
memset ((char *) &salocal, '\0', sizeof (salocal));
salocal.sin_family = AF_INET;
salocal.sin_addr.s_addr = packet->src_ipaddr;
return sendfromto(packet->sockfd, packet->data, (int)packet->data_len, 0,
(struct sockaddr *)&salocal, sizeof(struct sockaddr_in),
(struct sockaddr *)&saremote, sizeof(struct sockaddr_in));
}
#endif
}
/*
* Validates the requesting client NAS. Calculates the
* signature based on the clients private key.
*/
static int calc_acctdigest(RADIUS_PACKET *packet, const char *secret)
{
u_char digest[AUTH_VECTOR_LEN];
MD5_CTX context;
/*
* Older clients have the authentication vector set to
* all zeros. Return `1' in that case.
*/
memset(digest, 0, sizeof(digest));
if (memcmp(packet->vector, digest, AUTH_VECTOR_LEN) == 0) {
packet->verified = 1;
return 1;
}
/*
* Zero out the auth_vector in the received packet.
* Then append the shared secret to the received packet,
* and calculate the MD5 sum. This must be the same
* as the original MD5 sum (packet->vector).
*/
memset(packet->data + 4, 0, AUTH_VECTOR_LEN);
/*
* MD5(packet + secret);
*/
MD5Init(&context);
MD5Update(&context, packet->data, packet->data_len);
MD5Update(&context, secret, strlen(secret));
MD5Final(digest, &context);
/*
* Return 0 if OK, 2 if not OK.
*/
packet->verified =
memcmp(digest, packet->vector, AUTH_VECTOR_LEN) ? 2 : 0;
return packet->verified;
}
/*
* Validates the requesting client NAS. Calculates the
* signature based on the clients private key.
*/
static int calc_replydigest(RADIUS_PACKET *packet, RADIUS_PACKET *original,
const char *secret)
{
uint8_t calc_digest[AUTH_VECTOR_LEN];
MD5_CTX context;
/*
* Very bad!
*/
if (original == NULL) {
return 3;
}
/*
* Copy the original vector in place.
*/
memcpy(packet->data + 4, original->vector, AUTH_VECTOR_LEN);
/*
* MD5(packet + secret);
*/
MD5Init(&context);
MD5Update(&context, packet->data, packet->data_len);
MD5Update(&context, secret, strlen(secret));
MD5Final(calc_digest, &context);
/*
* Copy the packet's vector back to the packet.
*/
memcpy(packet->data + 4, packet->vector, AUTH_VECTOR_LEN);
/*
* Return 0 if OK, 2 if not OK.
*/
packet->verified =
memcmp(packet->vector, calc_digest, AUTH_VECTOR_LEN) ? 2 : 0;
return packet->verified;
}
/*
* Receive UDP client requests, and fill in
* the basics of a RADIUS_PACKET structure.
*/
RADIUS_PACKET *rad_recv(int fd)
{
RADIUS_PACKET *packet;
struct sockaddr_in saremote;
int totallen;
socklen_t salen;
uint8_t *attr;
int count;
radius_packet_t *hdr;
char host_ipaddr[16];
int require_ma = 0;
int seen_ma = 0;
uint8_t data[MAX_PACKET_LEN];
int num_attributes;
/*
* Allocate the new request data structure
*/
if ((packet = malloc(sizeof(RADIUS_PACKET))) == NULL) {
librad_log("out of memory");
return NULL;
}
memset(packet, 0, sizeof(RADIUS_PACKET));
/*
* Receive the packet.
*/
salen = sizeof(saremote);
memset(&saremote, 0, sizeof(saremote));
#ifndef WITH_UDPFROMTO
packet->data_len = recvfrom(fd, data, sizeof(data),
0, (struct sockaddr *)&saremote, &salen);
packet->dst_ipaddr = htonl(INADDR_ANY); /* i.e. unknown */
#else
{
socklen_t salen_local;
struct sockaddr_in salocal;
salen_local = sizeof(salocal);
memset(&salocal, 0, sizeof(salocal));
packet->data_len = recvfromto(fd, data, sizeof(data), 0,
(struct sockaddr *)&saremote, &salen,
(struct sockaddr *)&salocal, &salen_local);
packet->dst_ipaddr = salocal.sin_addr.s_addr;
}
#endif
/*
* Check for socket errors.
*/
if (packet->data_len < 0) {
librad_log("Error receiving packet: %s", strerror(errno));
free(packet);
return NULL;
}
/*
* Fill IP header fields. We need these for the error
* messages which may come later.
*/
packet->sockfd = fd;
packet->src_ipaddr = saremote.sin_addr.s_addr;
packet->src_port = ntohs(saremote.sin_port);
/*
* FIXME: Do even more filtering by only permitting
* certain IP's. The problem is that we don't know
* how to do this properly for all possible clients...
*/
/*
* Explicitely set the VP list to empty.
*/
packet->vps = NULL;
/*
* Check for packets smaller than the packet header.
*
* RFC 2865, Section 3., subsection 'length' says:
*
* "The minimum length is 20 ..."
*/
if (packet->data_len < AUTH_HDR_LEN) {
librad_log("WARNING: Malformed RADIUS packet from host %s: too short (received %d < minimum %d)",
ip_ntoa(host_ipaddr, packet->src_ipaddr),
packet->data_len, AUTH_HDR_LEN);
free(packet);
return NULL;
}
/*
* RFC 2865, Section 3., subsection 'length' says:
*
* " ... and maximum length is 4096."
*/
if (packet->data_len > MAX_PACKET_LEN) {
librad_log("WARNING: Malformed RADIUS packet from host %s: too long (received %d > maximum %d)",
ip_ntoa(host_ipaddr, packet->src_ipaddr),
packet->data_len, MAX_PACKET_LEN);
free(packet);
return NULL;
}
/*
* Check for packets with mismatched size.
* i.e. We've received 128 bytes, and the packet header
* says it's 256 bytes long.
*/
totallen = (data[2] << 8) | data[3];
hdr = (radius_packet_t *)data;
/*
* Code of 0 is not understood.
* Code of 16 or greate is not understood.
*/
if ((hdr->code == 0) ||
(hdr->code >= 52)) {
librad_log("WARNING: Bad RADIUS packet from host %s: unknown packet code %d",
ip_ntoa(host_ipaddr, packet->src_ipaddr),
hdr->code);
free(packet);
return NULL;
}
/*
* Message-Authenticator is required in Status-Server
* packets, otherwise they can be trivially forged.
*/
if (hdr->code == PW_STATUS_SERVER) require_ma = 1;
/*
* Repeat the length checks. This time, instead of
* looking at the data we received, look at the value
* of the 'length' field inside of the packet.
*
* Check for packets smaller than the packet header.
*
* RFC 2865, Section 3., subsection 'length' says:
*
* "The minimum length is 20 ..."
*/
if (totallen < AUTH_HDR_LEN) {
librad_log("WARNING: Malformed RADIUS packet from host %s: too short (length %d < minimum %d)",
ip_ntoa(host_ipaddr, packet->src_ipaddr),
totallen, AUTH_HDR_LEN);
free(packet);
return NULL;
}
/*
* And again, for the value of the 'length' field.
*
* RFC 2865, Section 3., subsection 'length' says:
*
* " ... and maximum length is 4096."
*/
if (totallen > MAX_PACKET_LEN) {
librad_log("WARNING: Malformed RADIUS packet from host %s: too long (length %d > maximum %d)",
ip_ntoa(host_ipaddr, packet->src_ipaddr),
totallen, MAX_PACKET_LEN);
free(packet);
return NULL;
}
/*
* RFC 2865, Section 3., subsection 'length' says:
*
* "If the packet is shorter than the Length field
* indicates, it MUST be silently discarded."
*
* i.e. No response to the NAS.
*/
if (packet->data_len < totallen) {
librad_log("WARNING: Malformed RADIUS packet from host %s: received %d octets, packet length says %d",
ip_ntoa(host_ipaddr, packet->src_ipaddr),
packet->data_len, totallen);
free(packet);
return NULL;
}
/*
* RFC 2865, Section 3., subsection 'length' says:
*
* "Octets outside the range of the Length field MUST be
* treated as padding and ignored on reception."
*/
if (packet->data_len > totallen) {
/*
* We're shortening the packet below, but just
* to be paranoid, zero out the extra data.
*/
memset(data + totallen, 0, packet->data_len - totallen);
packet->data_len = totallen;
}
/*
* Walk through the packet's attributes, ensuring that
* they add up EXACTLY to the size of the packet.
*
* If they don't, then the attributes either under-fill
* or over-fill the packet. Any parsing of the packet
* is impossible, and will result in unknown side effects.
*
* This would ONLY happen with buggy RADIUS implementations,
* or with an intentional attack. Either way, we do NOT want
* to be vulnerable to this problem.
*/
attr = hdr->data;
count = totallen - AUTH_HDR_LEN;
num_attributes = 0;
while (count > 0) {
/*
* Attribute number zero is NOT defined.
*/
if (attr[0] == 0) {
librad_log("WARNING: Malformed RADIUS packet from host %s: Invalid attribute 0",
ip_ntoa(host_ipaddr, packet->src_ipaddr));
free(packet);
return NULL;
}
/*
* Attributes are at LEAST as long as the ID & length
* fields. Anything shorter is an invalid attribute.
*/
if (attr[1] < 2) {
librad_log("WARNING: Malformed RADIUS packet from host %s: attribute %d too short",
ip_ntoa(host_ipaddr, packet->src_ipaddr),
attr[0]);
free(packet);
return NULL;
}
/*
* Sanity check the attributes for length.
*/
switch (attr[0]) {
default: /* don't do anything by default */
break;
/*
* If there's an EAP-Message, we require
* a Message-Authenticator.
*/
case PW_EAP_MESSAGE:
require_ma = 1;
break;
case PW_MESSAGE_AUTHENTICATOR:
if (attr[1] != 2 + AUTH_VECTOR_LEN) {
librad_log("WARNING: Malformed RADIUS packet from host %s: Message-Authenticator has invalid length %d",
ip_ntoa(host_ipaddr, packet->src_ipaddr),
attr[1] - 2);
free(packet);
return NULL;
}
seen_ma = 1;
break;
}
/*
* FIXME: Look up the base 255 attributes in the
* dictionary, and switch over their type. For
* integer/date/ip, the attribute length SHOULD
* be 6.
*/
count -= attr[1]; /* grab the attribute length */
attr += attr[1];
num_attributes++; /* seen one more attribute */
}
/*
* If the attributes add up to a packet, it's allowed.
*
* If not, we complain, and throw the packet away.
*/
if (count != 0) {
librad_log("WARNING: Malformed RADIUS packet from host %s: packet attributes do NOT exactly fill the packet",
ip_ntoa(host_ipaddr, packet->src_ipaddr));
free(packet);
return NULL;
}
/*
* If we're configured to look for a maximum number of
* attributes, and we've seen more than that maximum,
* then throw the packet away, as a possible DoS.
*/
if ((librad_max_attributes > 0) &&
(num_attributes > librad_max_attributes)) {
librad_log("WARNING: Possible DoS attack from host %s: Too many attributes in request (received %d, max %d are allowed).",
ip_ntoa(host_ipaddr, packet->src_ipaddr),
num_attributes, librad_max_attributes);
free(packet);
return NULL;
}
/*
* http://www.freeradius.org/rfc/rfc2869.html#EAP-Message
*
* A packet with an EAP-Message attribute MUST also have
* a Message-Authenticator attribute.
*
* A Message-Authenticator all by itself is OK, though.
*
* Similarly, Status-Server packets MUST contain
* Message-Authenticator attributes.
*/
if (require_ma && ! seen_ma) {
librad_log("WARNING: Insecure packet from host %s: Packet does not contain required Message-Authenticator attribute",
ip_ntoa(host_ipaddr, packet->src_ipaddr));
free(packet);
return NULL;
}
if (librad_debug) {
if ((hdr->code > 0) && (hdr->code < 52)) {
printf("rad_recv: %s packet from host %s:%d",
packet_codes[hdr->code],
ip_ntoa(host_ipaddr, packet->src_ipaddr), packet->src_port);
} else {
printf("rad_recv: Packet from host %s:%d code=%d",
ip_ntoa(host_ipaddr, packet->src_ipaddr), packet->src_port,
hdr->code);
}
printf(", id=%d, length=%d\n", hdr->id, totallen);
}
/*
* Fill RADIUS header fields
*/
packet->code = hdr->code;
packet->id = hdr->id;
memcpy(packet->vector, hdr->vector, AUTH_VECTOR_LEN);
/*
* Now that we've sanity checked the packet, we can allocate
* memory for it, and copy the data from the local area to
* the packet buffer.
*/
if ((packet->data = malloc(packet->data_len)) == NULL) {
free(packet);
librad_log("out of memory");
return NULL;
}
memcpy(packet->data, data, packet->data_len);
return packet;
}
/*
* Verify the signature of a packet.
*/
int rad_verify(RADIUS_PACKET *packet, RADIUS_PACKET *original,
const char *secret)
{
uint8_t *ptr;
int length;
int attrlen;
if (!packet || !packet->data) return -1;
/*
* Before we allocate memory for the attributes, do more
* sanity checking.
*/
ptr = packet->data + AUTH_HDR_LEN;
length = packet->data_len - AUTH_HDR_LEN;
while (length > 0) {
uint8_t msg_auth_vector[AUTH_VECTOR_LEN];
uint8_t calc_auth_vector[AUTH_VECTOR_LEN];
attrlen = ptr[1];
switch (ptr[0]) {
default: /* don't do anything. */
break;
/*
* Note that more than one Message-Authenticator
* attribute is invalid.
*/
case PW_MESSAGE_AUTHENTICATOR:
memcpy(msg_auth_vector, &ptr[2], sizeof(msg_auth_vector));
memset(&ptr[2], 0, AUTH_VECTOR_LEN);
switch (packet->code) {
default:
break;
case PW_ACCOUNTING_REQUEST:
case PW_ACCOUNTING_RESPONSE:
case PW_DISCONNECT_REQUEST:
case PW_DISCONNECT_ACK:
case PW_DISCONNECT_NAK:
case PW_COA_REQUEST:
case PW_COA_ACK:
case PW_COA_NAK:
memset(packet->data + 4, 0, AUTH_VECTOR_LEN);
break;
case PW_AUTHENTICATION_ACK:
case PW_AUTHENTICATION_REJECT:
case PW_ACCESS_CHALLENGE:
if (!original) {
librad_log("ERROR: Cannot validate Message-Authenticator in response packet without a request packet.");
return -1;
}
memcpy(packet->data + 4, original->vector, AUTH_VECTOR_LEN);
break;
}
lrad_hmac_md5(packet->data, packet->data_len,
secret, strlen(secret), calc_auth_vector);
if (memcmp(calc_auth_vector, msg_auth_vector,
sizeof(calc_auth_vector)) != 0) {
char buffer[32];
librad_log("Received packet from %s with invalid Message-Authenticator! (Shared secret is incorrect.)",
ip_ntoa(buffer, packet->src_ipaddr));
/* Silently drop packet, according to RFC 3579 */
return -2;
} /* else the message authenticator was good */
/*
* Reinitialize Authenticators.
*/
memcpy(&ptr[2], msg_auth_vector, AUTH_VECTOR_LEN);
memcpy(packet->data + 4, packet->vector, AUTH_VECTOR_LEN);
break;
} /* switch over the attributes */
ptr += attrlen;
length -= attrlen;
} /* loop over the packet, sanity checking the attributes */
/*
* Calculate and/or verify digest.
*/
switch(packet->code) {
int rcode;
case PW_AUTHENTICATION_REQUEST:
case PW_STATUS_SERVER:
case PW_DISCONNECT_REQUEST:
/*
* The authentication vector is random
* nonsense, invented by the client.
*/
break;
case PW_ACCOUNTING_REQUEST:
if (calc_acctdigest(packet, secret) > 1) {
char buffer[32];
librad_log("Received Accounting-Request packet "
"from %s with invalid signature! (Shared secret is incorrect.)",
ip_ntoa(buffer, packet->src_ipaddr));
return -1;
}
break;
/* Verify the reply digest */
case PW_AUTHENTICATION_ACK:
case PW_AUTHENTICATION_REJECT:
case PW_ACCESS_CHALLENGE:
case PW_ACCOUNTING_RESPONSE:
rcode = calc_replydigest(packet, original, secret);
if (rcode > 1) {
char buffer[32];
librad_log("Received %s packet "
"from client %s port %d with invalid signature (err=%d)! (Shared secret is incorrect.)",
packet_codes[packet->code],
ip_ntoa(buffer, packet->src_ipaddr),
packet->src_port,
rcode);
return -1;
}
break;
}
return 0;
}
/*
* Parse a RADIUS attribute into a data structure.
*/
static VALUE_PAIR *rad_attr2vp(const RADIUS_PACKET *packet, const RADIUS_PACKET *original,
const char *secret, int attribute, int length,
const uint8_t *data)
{
int offset = 0;
VALUE_PAIR *vp;
if ((vp = paircreate(attribute, PW_TYPE_OCTETS)) == NULL) {
return NULL;
}
/*
* If length is greater than 253, something is SERIOUSLY
* wrong.
*/
if (length > 253) length = 253; /* paranoia (pair-anoia?) */
vp->length = length;
vp->operator = T_OP_EQ;
vp->next = NULL;
/*
* Handle tags.
*/
if (vp->flags.has_tag) {
if (TAG_VALID(data[0]) ||
(vp->flags.encrypt == FLAG_ENCRYPT_TUNNEL_PASSWORD)) {
/*
* Tunnel passwords REQUIRE a tag, even
* if don't have a valid tag.
*/
vp->flags.tag = data[0];
if ((vp->type == PW_TYPE_STRING) ||
(vp->type == PW_TYPE_OCTETS)) offset = 1;
}
}
/*
* Copy the data to be decrypted
*/
memcpy(&vp->strvalue[0], data + offset, length - offset);
vp->length -= offset;
/*
* Decrypt the attribute.
*/
switch (vp->flags.encrypt) {
/*
* User-Password
*/
case FLAG_ENCRYPT_USER_PASSWORD:
if (original) {
rad_pwdecode((char *)vp->strvalue,
vp->length, secret,
original->vector);
} else {
rad_pwdecode((char *)vp->strvalue,
vp->length, secret,
packet->vector);
}
if (vp->attribute == PW_USER_PASSWORD) {
vp->length = strlen(vp->strvalue);
}
break;
/*
* Tunnel-Password's may go ONLY
* in response packets.
*/
case FLAG_ENCRYPT_TUNNEL_PASSWORD:
if (!original) goto raw;
if (rad_tunnel_pwdecode(vp->strvalue, &vp->length,
secret, original->vector) < 0) {
goto raw;
}
break;
/*
* Ascend-Send-Secret
* Ascend-Receive-Secret
*/
case FLAG_ENCRYPT_ASCEND_SECRET:
if (!original) {
goto raw;
} else {
uint8_t my_digest[AUTH_VECTOR_LEN];
make_secret(my_digest,
original->vector,
secret, data);
memcpy(vp->strvalue, my_digest,
AUTH_VECTOR_LEN );
vp->strvalue[AUTH_VECTOR_LEN] = '\0';
vp->length = strlen(vp->strvalue);
}
break;
default:
break;
} /* switch over encryption flags */
switch (vp->type) {
case PW_TYPE_STRING:
case PW_TYPE_OCTETS:
case PW_TYPE_ABINARY:
/* nothing more to do */
break;
case PW_TYPE_INTEGER:
if (vp->length != 4) goto raw;
memcpy(&vp->lvalue, vp->strvalue, 4);
vp->lvalue = ntohl(vp->lvalue);
if (vp->flags.has_tag) vp->lvalue &= 0x00ffffff;
/*
* Try to get named VALUEs
*/
{
DICT_VALUE *dval;
dval = dict_valbyattr(vp->attribute,
vp->lvalue);
if (dval) {
strNcpy(vp->strvalue,
dval->name,
sizeof(vp->strvalue));
}
}
break;
case PW_TYPE_DATE:
if (vp->length != 4) goto raw;
memcpy(&vp->lvalue, vp->strvalue, 4);
vp->lvalue = ntohl(vp->lvalue);
break;
/*
* IPv4 address. Keep it in network byte order in
* vp->lvalue and put ASCII IP address in standard
* dot notation into vp->strvalue.
*/
case PW_TYPE_IPADDR:
if (vp->length != 4) goto raw;
memcpy(&vp->lvalue, vp->strvalue, 4);
ip_ntoa(vp->strvalue, vp->lvalue);
break;
/*
* IPv6 interface ID is 8 octets long.
*/
case PW_TYPE_IFID:
if (vp->length != 8) goto raw;
/* vp->vp_ifid == vp->strvalue */
break;
/*
* IPv6 addresses are 16 octets long
*/
case PW_TYPE_IPV6ADDR:
if (vp->length != 16) goto raw;
/* vp->vp_ipv6addr == vp->strvalue */
break;
/*
* IPv6 prefixes are 2 to 18 octets long.
*
* RFC 3162: The first octet is unused.
* The second is the length of the prefix
* the rest are the prefix data.
*
* The prefix length can have value 0 to 128.
*/
case PW_TYPE_IPV6PREFIX:
if (vp->length < 2 || vp->length > 18) goto raw;
if (vp->strvalue[1] > 128) goto raw;
/*
* FIXME: double-check that
* (vp->strvalue[1] >> 3) matches vp->length + 2
*/
if (vp->length < 18) {
memset(vp->strvalue + vp->length, 0,
18 - vp->length);
}
break;
default:
raw:
vp->type = PW_TYPE_OCTETS;
vp->length = length;
memcpy(vp->strvalue, data, length);
/*
* Ensure there's no encryption or tag stuff,
* we just pass the attribute as-is.
*/
memset(&vp->flags, 0, sizeof(vp->flags));
}
return vp;
}
/*
* Calculate/check digest, and decode radius attributes.
*/
int rad_decode(RADIUS_PACKET *packet, RADIUS_PACKET *original,
const char *secret)
{
uint32_t lvalue;
uint32_t vendorcode;
VALUE_PAIR **tail;
VALUE_PAIR *pair;
uint8_t *ptr;
int packet_length;
int attribute;
int attrlen;
int vendorlen;
radius_packet_t *hdr;
int vsa_tlen, vsa_llen;
DICT_VENDOR *dv = NULL;
/*
* Extract attribute-value pairs
*/
hdr = (radius_packet_t *)packet->data;
ptr = hdr->data;
packet_length = packet->data_len - AUTH_HDR_LEN;
/*
* There may be VP's already in the packet. Don't
* destroy them.
*/
for (tail = &packet->vps; *tail != NULL; tail = &((*tail)->next)) {
/* nothing */
}
vendorcode = 0;
vendorlen = 0;
vsa_tlen = vsa_llen = 1;
/*
* We have to read at least two bytes.
*
* rad_recv() above ensures that this is OK.
*/
while (packet_length > 0) {
attribute = -1;
attrlen = -1;
/*
* Normal attribute, handle it like normal.
*/
if (vendorcode == 0) {
/*
* No room to read attr/length,
* or bad attribute, or attribute is
* too short, or attribute is too long,
* stop processing the packet.
*/
if ((packet_length < 2) ||
(ptr[0] == 0) || (ptr[1] < 2) ||
(ptr[1] > packet_length)) break;
attribute = *ptr++;
attrlen = *ptr++;
attrlen -= 2;
packet_length -= 2;
if (attribute != PW_VENDOR_SPECIFIC) goto create_pair;
/*
* No vendor code, or ONLY vendor code.
*/
if (attrlen <= 4) goto create_pair;
vendorlen = 0;
}
/*
* Handle Vendor-Specific
*/
if (vendorlen == 0) {
uint8_t *subptr;
int sublen;
int myvendor;
/*
* attrlen was checked above.
*/
memcpy(&lvalue, ptr, 4);
myvendor = ntohl(lvalue);
/*
* Zero isn't allowed.
*/
if (myvendor == 0) goto create_pair;
/*
* This is an implementation issue.
* We currently pack vendor into the upper
* 16 bits of a 32-bit attribute number,
* so we can't handle vendor numbers larger
* than 16 bits.
*/
if (myvendor > 65535) goto create_pair;
vsa_tlen = vsa_llen = 1;
dv = dict_vendorbyvalue(myvendor);
if (dv) {
vsa_tlen = dv->type;
vsa_llen = dv->length;
}
/*
* Sweep through the list of VSA's,
* seeing if they exactly fill the
* outer Vendor-Specific attribute.
*
* If not, create a raw Vendor-Specific.
*/
subptr = ptr + 4;
sublen = attrlen - 4;
/*
* See if we can parse it.
*/
do {
int myattr = 0;
/*
* Don't have a type, it's bad.
*/
if (sublen < vsa_tlen) goto create_pair;
/*
* Ensure that the attribute number
* is OK.
*/
switch (vsa_tlen) {
case 1:
myattr = subptr[0];
break;
case 2:
myattr = (subptr[0] << 8) | subptr[1];
break;
case 4:
if ((subptr[0] != 0) ||
(subptr[1] != 0)) goto create_pair;
myattr = (subptr[2] << 8) | subptr[3];
break;
/*
* Our dictionary is broken.
*/
default:
goto create_pair;
}
/*
* Not enough room for one more
* attribute. Die!
*/
if (sublen < vsa_tlen + vsa_llen) goto create_pair;
switch (vsa_llen) {
case 0:
attribute = (myvendor << 16) | myattr;
ptr += 4 + vsa_tlen;
attrlen -= (4 + vsa_tlen);
packet_length -= 4 + vsa_tlen;
goto create_pair;
case 1:
if (subptr[vsa_tlen] < (vsa_tlen + vsa_llen))
goto create_pair;
if (subptr[vsa_tlen] > sublen)
goto create_pair;
sublen -= subptr[vsa_tlen];
subptr += subptr[vsa_tlen];
break;
case 2:
if (subptr[vsa_tlen] != 0) goto create_pair;
if (subptr[vsa_tlen + 1] < (vsa_tlen + vsa_llen))
goto create_pair;
if (subptr[vsa_tlen + 1] > sublen)
goto create_pair;
sublen -= subptr[vsa_tlen + 1];
subptr += subptr[vsa_tlen + 1];
break;
/*
* Our dictionaries are
* broken.
*/
default:
goto create_pair;
}
} while (sublen > 0);
vendorcode = myvendor;
vendorlen = attrlen - 4;
packet_length -= 4;
ptr += 4;
}
/*
* attrlen is the length of this attribute.
* total_len is the length of the encompassing
* attribute.
*/
switch (vsa_tlen) {
case 1:
attribute = ptr[0];
break;
case 2:
attribute = (ptr[0] << 8) | ptr[1];
break;
default: /* can't hit this. */
return -1;
}
attribute |= (vendorcode << 16);
ptr += vsa_tlen;
switch (vsa_llen) {
case 1:
attrlen = ptr[0] - (vsa_tlen + vsa_llen);
break;
case 2:
attrlen = ptr[1] - (vsa_tlen + vsa_llen);
break;
default: /* can't hit this. */
return -1;
}
ptr += vsa_llen;
vendorlen -= vsa_tlen + vsa_llen + attrlen;
if (vendorlen == 0) vendorcode = 0;
packet_length -= (vsa_tlen + vsa_llen);
/*
* Create the attribute, setting the default type
* to 'octects'. If the type in the dictionary
* is different, then the dictionary type will
* over-ride this one.
*/
create_pair:
pair = rad_attr2vp(packet, original, secret,
attribute, attrlen, ptr);
if (!pair) {
pairfree(&packet->vps);
librad_log("out of memory");
return -1;
}
debug_pair(pair);
*tail = pair;
tail = &pair->next;
ptr += attrlen;
packet_length -= attrlen;
}
/*
* Merge information from the outside world into our
* random pool.
*/
lrad_rand_seed(packet->data, AUTH_HDR_LEN);
return 0;
}
/*
* Encode password.
*
* We assume that the passwd buffer passed is big enough.
* RFC2138 says the password is max 128 chars, so the size
* of the passwd buffer must be at least 129 characters.
* Preferably it's just MAX_STRING_LEN.
*
* int *pwlen is updated to the new length of the encrypted
* password - a multiple of 16 bytes.
*/
int rad_pwencode(char *passwd, int *pwlen, const char *secret,
const char *vector)
{
uint8_t buffer[AUTH_VECTOR_LEN + MAX_STRING_LEN + 1];
char digest[AUTH_VECTOR_LEN];
int i, n, secretlen;
int len;
/*
* Pad password to multiple of AUTH_PASS_LEN bytes.
*/
len = *pwlen;
if (len > 128) len = 128;
*pwlen = len;
if (len % AUTH_PASS_LEN != 0) {
n = AUTH_PASS_LEN - (len % AUTH_PASS_LEN);
for (i = len; n > 0; n--, i++)
passwd[i] = 0;
len = *pwlen = i;
} else if (len == 0) {
memset(passwd, 0, AUTH_PASS_LEN);
*pwlen = len = AUTH_PASS_LEN;
}
/*
* Use the secret to setup the decryption digest
*/
secretlen = strlen(secret);
memcpy(buffer, secret, secretlen);
memcpy(buffer + secretlen, vector, AUTH_VECTOR_LEN);
librad_md5_calc((u_char *)digest, buffer, secretlen + AUTH_VECTOR_LEN);
/*
* Now we can encode the password *in place*
*/
for (i = 0; i < AUTH_PASS_LEN; i++)
passwd[i] ^= digest[i];
if (len <= AUTH_PASS_LEN) return 0;
/*
* Length > AUTH_PASS_LEN, so we need to use the extended
* algorithm.
*/
for (n = 0; n < 128 && n <= (len - AUTH_PASS_LEN); n += AUTH_PASS_LEN) {
memcpy(buffer + secretlen, passwd + n, AUTH_PASS_LEN);
librad_md5_calc((u_char *)digest, buffer, secretlen + AUTH_PASS_LEN);
for (i = 0; i < AUTH_PASS_LEN; i++)
passwd[i + n + AUTH_PASS_LEN] ^= digest[i];
}
return 0;
}
/*
* Decode password.
*/
int rad_pwdecode(char *passwd, int pwlen, const char *secret,
const char *vector)
{
uint8_t buffer[AUTH_VECTOR_LEN + MAX_STRING_LEN + 1];
char digest[AUTH_VECTOR_LEN];
char r[AUTH_VECTOR_LEN];
char *s;
int i, n, secretlen;
int rlen;
/*
* Use the secret to setup the decryption digest
*/
secretlen = strlen(secret);
memcpy(buffer, secret, secretlen);
memcpy(buffer + secretlen, vector, AUTH_VECTOR_LEN);
librad_md5_calc((u_char *)digest, buffer, secretlen + AUTH_VECTOR_LEN);
/*
* Now we can decode the password *in place*
*/
memcpy(r, passwd, AUTH_PASS_LEN);
for (i = 0; i < AUTH_PASS_LEN && i < pwlen; i++)
passwd[i] ^= digest[i];
if (pwlen <= AUTH_PASS_LEN) {
passwd[pwlen+1] = 0;
return pwlen;
}
/*
* Length > AUTH_PASS_LEN, so we need to use the extended
* algorithm.
*/
rlen = ((pwlen - 1) / AUTH_PASS_LEN) * AUTH_PASS_LEN;
for (n = rlen; n > 0; n -= AUTH_PASS_LEN ) {
s = (n == AUTH_PASS_LEN) ? r : (passwd + n - AUTH_PASS_LEN);
memcpy(buffer + secretlen, s, AUTH_PASS_LEN);
librad_md5_calc((u_char *)digest, buffer, secretlen + AUTH_PASS_LEN);
for (i = 0; i < AUTH_PASS_LEN && (i + n) < pwlen; i++)
passwd[i + n] ^= digest[i];
}
passwd[pwlen] = 0;
return pwlen;
}
/*
* Encode Tunnel-Password attributes when sending them out on the wire.
*
* int *pwlen is updated to the new length of the encrypted
* password - a multiple of 16 bytes.
*
* This is per RFC-2868 which adds a two char SALT to the initial intermediate
* value MD5 hash.
*/
int rad_tunnel_pwencode(char *passwd, int *pwlen, const char *secret,
const char *vector)
{
uint8_t buffer[AUTH_VECTOR_LEN + MAX_STRING_LEN + 3];
unsigned char digest[AUTH_VECTOR_LEN];
char* salt;
int i, n, secretlen;
unsigned len, n2;
len = *pwlen;
if (len > 127) len = 127;
/*
* Shift the password 3 positions right to place a salt and original
* length, tag will be added automatically on packet send
*/
for (n=len ; n>=0 ; n--) passwd[n+3] = passwd[n];
salt = passwd;
passwd += 2;
/*
* save original password length as first password character;
*/
*passwd = len;
len += 1;
/*
* Generate salt. The RFC's say:
*
* The high bit of salt[0] must be set, each salt in a
* packet should be unique, and they should be random
*
* So, we set the high bit, add in a counter, and then
* add in some CSPRNG data. should be OK..
*/
salt[0] = (0x80 | ( ((salt_offset++) & 0x0f) << 3) |
(lrad_rand() & 0x07));
salt[1] = lrad_rand();
/*
* Padd password to multiple of AUTH_PASS_LEN bytes.
*/
n = len % AUTH_PASS_LEN;
if (n) {
n = AUTH_PASS_LEN - n;
for (; n > 0; n--, len++)
passwd[len] = 0;
}
/* set new password length */
*pwlen = len + 2;
/*
* Use the secret to setup the decryption digest
*/
secretlen = strlen(secret);
memcpy(buffer, secret, secretlen);
for (n2 = 0; n2 < len; n2+=AUTH_PASS_LEN) {
if (!n2) {
memcpy(buffer + secretlen, vector, AUTH_VECTOR_LEN);
memcpy(buffer + secretlen + AUTH_VECTOR_LEN, salt, 2);
librad_md5_calc(digest, buffer, secretlen + AUTH_VECTOR_LEN + 2);
} else {
memcpy(buffer + secretlen, passwd + n2 - AUTH_PASS_LEN, AUTH_PASS_LEN);
librad_md5_calc(digest, buffer, secretlen + AUTH_PASS_LEN);
}
for (i = 0; i < AUTH_PASS_LEN; i++) {
passwd[i + n2] ^= digest[i];
}
}
passwd[n2] = 0;
return 0;
}
/*
* Decode Tunnel-Password encrypted attributes.
*
* Defined in RFC-2868, this uses a two char SALT along with the
* initial intermediate value, to differentiate it from the
* above.
*/
int rad_tunnel_pwdecode(uint8_t *passwd, int *pwlen, const char *secret,
const char *vector)
{
uint8_t buffer[AUTH_VECTOR_LEN + MAX_STRING_LEN + 3];
uint8_t digest[AUTH_VECTOR_LEN];
uint8_t decrypted[MAX_STRING_LEN + 1];
int secretlen;
unsigned i, n, len;
len = *pwlen;
/*
* We need at least a salt.
*/
if (len < 2) {
librad_log("tunnel password is too short");
return -1;
}
/*
* There's a salt, but no password. Or, there's a salt
* and a 'data_len' octet. It's wrong, but at least we
* can figure out what it means: the password is empty.
*
* Note that this means we ignore the 'data_len' field,
* if the attribute length tells us that there's no
* more data. So the 'data_len' field may be wrong,
* but that's ok...
*/
if (len <= 3) {
passwd[0] = 0;
*pwlen = 0;
return 0;
}
len -= 2; /* discount the salt */
/*
* Use the secret to setup the decryption digest
*/
secretlen = strlen(secret);
/*
* Set up the initial key:
*
* b(1) = MD5(secret + vector + salt)
*/
memcpy(buffer, secret, secretlen);
memcpy(buffer + secretlen, vector, AUTH_VECTOR_LEN);
memcpy(buffer + secretlen + AUTH_VECTOR_LEN, passwd, 2);
librad_md5_calc(digest, buffer, secretlen + AUTH_VECTOR_LEN + 2);
/*
* A quick check: decrypt the first octet of the password,
* which is the 'data_len' field. Ensure it's sane.
*
* 'n' doesn't include the 'data_len' octet
* 'len' does.
*/
n = passwd[2] ^ digest[0];
if (n >= len) {
librad_log("tunnel password is too long for the attribute");
return -1;
}
/*
* Loop over the data, decrypting it, and generating
* the key for the next round of decryption.
*/
for (n = 0; n < len; n += AUTH_PASS_LEN) {
for (i = 0; i < AUTH_PASS_LEN; i++) {
decrypted[n + i] = passwd[n + i + 2] ^ digest[i];
/*
* Encrypted password may not be aligned
* on 16 octets, so we catch that here...
*/
if ((n + i) == len) break;
}
/*
* Update the digest, based on
*
* b(n) = MD5(secret + cleartext(n-1)
*
* but only if there's more data...
*/
memcpy(buffer + secretlen, passwd + n + 2, AUTH_PASS_LEN);
librad_md5_calc(digest, buffer, secretlen + AUTH_PASS_LEN);
}
/*
* We've already validated the length of the decrypted
* password. Copy it back to the caller.
*/
memcpy(passwd, decrypted + 1, decrypted[0]);
passwd[decrypted[0]] = 0;
*pwlen = decrypted[0];
return decrypted[0];
}
/*
* Encode a CHAP password
*
* FIXME: might not work with Ascend because
* we use vp->length, and Ascend gear likes
* to send an extra '\0' in the string!
*/
int rad_chap_encode(RADIUS_PACKET *packet, char *output, int id,
VALUE_PAIR *password)
{
int i;
char *ptr;
char string[MAX_STRING_LEN * 2 + 1];
VALUE_PAIR *challenge;
/*
* Sanity check the input parameters
*/
if ((packet == NULL) || (password == NULL)) {
return -1;
}
/*
* Note that the password VP can be EITHER
* a User-Password attribute (from a check-item list),
* or a CHAP-Password attribute (the client asking
* the library to encode it).
*/
i = 0;
ptr = string;
*ptr++ = id;
i++;
memcpy(ptr, password->strvalue, password->length);
ptr += password->length;
i += password->length;
/*
* Use Chap-Challenge pair if present,
* Request-Authenticator otherwise.
*/
challenge = pairfind(packet->vps, PW_CHAP_CHALLENGE);
if (challenge) {
memcpy(ptr, challenge->strvalue, challenge->length);
i += challenge->length;
} else {
memcpy(ptr, packet->vector, AUTH_VECTOR_LEN);
i += AUTH_VECTOR_LEN;
}
*output = id;
librad_md5_calc((u_char *)output + 1, (u_char *)string, i);
return 0;
}
/*
* Seed the random number generator.
*
* May be called any number of times.
*/
void lrad_rand_seed(const void *data, size_t size)
{
uint32_t hash;
/*
* Ensure that the pool is initialized.
*/
if (lrad_rand_index < 0) {
int fd;
memset(&lrad_rand_pool, 0, sizeof(lrad_rand_pool));
fd = open("/dev/urandom", O_RDONLY);
if (fd >= 0) {
size_t total;
ssize_t this;
total = this = 0;
while (total < sizeof(lrad_rand_pool.randrsl)) {
this = read(fd, lrad_rand_pool.randrsl,
sizeof(lrad_rand_pool.randrsl) - total);
if ((this < 0) && (errno != EINTR)) break;
if (this > 0) total += this;
}
close(fd);
} else {
lrad_rand_pool.randrsl[0] = fd;
lrad_rand_pool.randrsl[1] = time(NULL);
lrad_rand_pool.randrsl[2] = errno;
}
lrad_randinit(&lrad_rand_pool, 1);
lrad_rand_index = 0;
}
if (!data) return;
/*
* Hash the user data
*/
hash = lrad_hash(data, size);
lrad_rand_pool.randrsl[lrad_rand_index & 0xff] ^= hash;
lrad_rand_index++;
lrad_rand_index &= 0xff;
/*
* Churn the pool every so often after seeding it.
*/
if (((int) (hash & 0xff)) == lrad_rand_index) {
lrad_isaac(&lrad_rand_pool);
}
}
/*
* Return a 32-bit random number.
*/
uint32_t lrad_rand(void)
{
uint32_t num;
/*
* Ensure that the pool is initialized.
*/
if (lrad_rand_index < 0) {
lrad_rand_seed(NULL, 0);
}
/*
* We don't return data directly from the pool.
* Rather, we return a summary of the data.
*/
num = lrad_rand_pool.randrsl[lrad_rand_index & 0xff];
lrad_rand_index++;
lrad_rand_index &= 0xff;
/*
* Every so often, churn the pool.
*/
if (((int) (num & 0xff)) == lrad_rand_index) {
lrad_isaac(&lrad_rand_pool);
}
return num;
}
/*
* Allocate a new RADIUS_PACKET
*/
RADIUS_PACKET *rad_alloc(int newvector)
{
RADIUS_PACKET *rp;
if ((rp = malloc(sizeof(RADIUS_PACKET))) == NULL) {
librad_log("out of memory");
return NULL;
}
memset(rp, 0, sizeof(RADIUS_PACKET));
if (newvector) {
int i;
uint32_t hash, base;
/*
* Don't expose the actual contents of the random
* pool.
*/
base = lrad_rand();
for (i = 0; i < AUTH_VECTOR_LEN; i += sizeof(uint32_t)) {
hash = lrad_rand() ^ base;
memcpy(rp->vector + i, &hash, sizeof(hash));
}
}
lrad_rand();
return rp;
}
/*
* Free a RADIUS_PACKET
*/
void rad_free(RADIUS_PACKET **radius_packet_ptr)
{
RADIUS_PACKET *radius_packet;
if (!radius_packet_ptr) return;
radius_packet = *radius_packet_ptr;
if (radius_packet->data) free(radius_packet->data);
if (radius_packet->vps) pairfree(&radius_packet->vps);
free(radius_packet);
*radius_packet_ptr = NULL;
}
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