ttls.c

使用最广泛的radius的linux的源码

/*
 * rlm_eap_ttls.c  contains the interfaces that are called from eap
 *
 * Version:     $Id: ttls.c,v 1.45 2008/03/07 09:53:26 aland Exp $
 *
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation; either version 2 of the License, or
 *   (at your option) any later version.
 *
 *   This program 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 General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program; if not, write to the Free Software
 *   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
 *
 *   Copyright 2003 Alan DeKok <[e-mail]>
 *   Copyright 2006 The FreeRADIUS server project
 */

#include <freeradius-devel/ident.h>
RCSID("$Id: ttls.c,v 1.45 2008/03/07 09:53:26 aland Exp $")

#include "eap_ttls.h"

/*
 *    0                   1                   2                   3
 *    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *   |                           AVP Code                            |
 *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *   |V M r r r r r r|                  AVP Length                   |
 *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *   |                        Vendor-ID (opt)                        |
 *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *   |    Data ...
 *   +-+-+-+-+-+-+-+-+
 */

/*
 *	Verify that the diameter packet is valid.
 */
static int diameter_verify(const uint8_t *data, unsigned int data_len)
{
	uint32_t attr;
	uint32_t length;
	unsigned int offset;
	unsigned int data_left = data_len;

	while (data_left > 0) {
		if (data_len < 12) {
			DEBUG2("  rlm_eap_ttls:  Diameter attribute is too small to contain a Diameter header");
			return 0;
		}

		rad_assert(data_left <= data_len);
		memcpy(&attr, data, sizeof(attr));
		data += 4;
		attr = ntohl(attr);
		if (attr > 255) {
			DEBUG2("  rlm_eap_ttls:  Non-RADIUS attribute in tunneled authentication is not supported");
			return 0;
		}

		memcpy(&length, data , sizeof(length));
		data += 4;
		length = ntohl(length);

		/*
		 *	A "vendor" flag, with a vendor ID of zero,
		 *	is equivalent to no vendor.  This is stupid.
		 */
		offset = 8;
		if ((length & (1 << 31)) != 0) {
			int attribute;
			uint32_t vendor;
			DICT_ATTR *da;

			memcpy(&vendor, data, sizeof(vendor));
			vendor = ntohl(vendor);

			if (vendor > 65535) {
				DEBUG2("  rlm_eap_ttls: Vendor codes larger than 65535 are not supported");
				return 0;
			}

			attribute = (vendor << 16) | attr;

			da = dict_attrbyvalue(attribute);

			/*
			 *	SHOULD check ((length & (1 << 30)) != 0)
			 *	for the mandatory bit.
			 */
			if (!da) {
				DEBUG2("  rlm_eap_ttls: Fatal! Vendor %u, Attribute %u was not found in our dictionary. ",
				       vendor, attr);
				return 0;
			}

			data += 4; /* skip the vendor field */
			offset += 4; /* offset to value field */
		}

		/*
		 *	Ignore the M bit.  We support all RADIUS attributes...
		 */

		/*
		 *	Get the length.  If it's too big, die.
		 */
		length &= 0x00ffffff;

		/*
		 *	Too short or too long is bad.
		 */
		if (length < offset) {
			DEBUG2("  rlm_eap_ttls: Tunneled attribute %d is too short (%d)to contain anything useful.", attr, length);
			return 0;
		}

		/*
		 *	EAP Messages cane be longer than MAX_STRING_LEN.
		 *	Other attributes cannot be.
		 */
		if ((attr != PW_EAP_MESSAGE) &&
		    (length > (MAX_STRING_LEN + 8))) {
			DEBUG2("  rlm_eap_ttls: Tunneled attribute %d is too long (%d) to pack into a RADIUS attribute.", attr, length);
			return 0;
		}

		if (length > data_left) {
			DEBUG2("  rlm_eap_ttls: Tunneled attribute %d is longer than room left in the packet (%d > %d).", attr, length, data_left);
			return 0;
		}

		/*
		 *	Check for broken implementations, which don't
		 *	pad the AVP to a 4-octet boundary.
		 */
		if (data_left == length) break;

		/*
		 *	The length does NOT include the padding, so
		 *	we've got to account for it here by rounding up
		 *	to the nearest 4-byte boundary.
		 */
		length += 0x03;
		length &= ~0x03;

		/*
		 *	If the rest of the diameter packet is larger than
		 *	this attribute, continue.
		 *
		 *	Otherwise, if the attribute over-flows the end
		 *	of the packet, die.
		 */
		if (data_left < length) {
			DEBUG2("  rlm_eap_ttls: ERROR! Diameter attribute overflows packet!");
			return 0;
		}

		/*
		 *	Check again for equality, now that we're padded
		 *	length to a multiple of 4 octets.
		 */
		if (data_left == length) break;

		/*
		 *	data_left > length, continue.
		 */
		data_left -= length;
		data += length - offset;
	}

	/*
	 *	We got this far.  It looks OK.
	 */
	return 1;
}


/*
 *	Convert diameter attributes to our VALUE_PAIR's
 */
static VALUE_PAIR *diameter2vp(SSL *ssl,
			       const uint8_t *data, size_t data_len)
{
	uint32_t	attr;
	uint32_t	length;
	size_t		offset;
	size_t		size;
	size_t		data_left = data_len;
	VALUE_PAIR	*first = NULL;
	VALUE_PAIR	**last = &first;
	VALUE_PAIR	*vp;

	while (data_left > 0) {
		rad_assert(data_left <= data_len);
		memcpy(&attr, data, sizeof(attr));
		data += 4;
		attr = ntohl(attr);

		memcpy(&length, data, sizeof(length));
		data += 4;
		length = ntohl(length);

		/*
		 *	A "vendor" flag, with a vendor ID of zero,
		 *	is equivalent to no vendor.  This is stupid.
		 */
		offset = 8;
		if ((length & (1 << 31)) != 0) {
			uint32_t vendor;

			memcpy(&vendor, data, sizeof(vendor));
			vendor = ntohl(vendor);

			if (attr > 65535) {
				DEBUG2("  rlm_eap_ttls: Cannot handle vendor attributes greater than 65535");
				pairfree(&first);
				return NULL;
			}

			if (vendor > 32767) {
				DEBUG2("  rlm_eap_ttls: Cannot handle vendor Id greater than 32767");
				pairfree(&first);
				return NULL;
			}

			attr |= (vendor << 16);

			data += 4; /* skip the vendor field, it's zero */
			offset += 4; /* offset to value field */
		}

		/*
		 *	Vendor attributes can be larger than 255.
		 *	Normal attributes cannot be.
		 */
		if ((attr > 255) && (VENDOR(attr) == 0)) {
			DEBUG2("  rlm_eap_ttls: Cannot handle Diameter attributes");
			pairfree(&first);
			return NULL;
		}

		/*
		 *	FIXME: Handle the M bit.  For now, we assume that
		 *	some other module takes care of any attribute
		 *	with the M bit set.
		 */
		
		/*
		 *	Get the length.
		 */
		length &= 0x00ffffff;

		/*
		 *	Get the size of the value portion of the
		 *	attribute.
		 */
		size = length - offset;

		/*
		 *	Create it.
		 */
		vp = paircreate(attr, PW_TYPE_OCTETS);
		if (!vp) {
			DEBUG2("  rlm_eap_ttls: Failure in creating VP");
			pairfree(&first);
			return NULL;
		}

		/*
		 *	If it's a type from our dictionary, then
		 *	we need to put the data in a relevant place.
		 */
		switch (vp->type) {
		case PW_TYPE_INTEGER:
		case PW_TYPE_DATE:
			if (size != vp->length) {
				DEBUG2("  rlm_eap_ttls: Invalid length attribute %d",
				       attr);
				pairfree(&first);
				pairfree(&vp);
				return NULL;
			}
			memcpy(&vp->vp_integer, data, vp->length);

			/*
			 *	Stored in host byte order: change it.
			 */
			vp->vp_integer = ntohl(vp->vp_integer);
			break;

		case PW_TYPE_IPADDR:
			if (size != vp->length) {
				DEBUG2("  rlm_eap_ttls: Invalid length attribute %d",
				       attr);
				pairfree(&first);
				pairfree(&vp);
				return NULL;
			}
		  memcpy(&vp->vp_ipaddr, data, vp->length);

		  /*
		   *	Stored in network byte order: don't change it.
		   */
		  break;

		  /*
		   *	String, octet, etc.  Copy the data from the
		   *	value field over verbatim.
		   *
		   *	FIXME: Ipv6 attributes ?
		   *
		   */
		case PW_TYPE_OCTETS:
			if (attr == PW_EAP_MESSAGE) {
				const uint8_t *eap_message = data;

				/*
				 *	vp exists the first time around.
				 */
				while (1) {
					vp->length = size;
					if (vp->length > 253) vp->length = 253;
					memcpy(vp->vp_octets, eap_message,
					       vp->length);

					size -= vp->length;
					eap_message += vp->length;

					*last = vp;
					last = &(vp->next);

					if (size == 0) break;

					vp = paircreate(attr, PW_TYPE_OCTETS);
					if (!vp) {
						DEBUG2("  rlm_eap_ttls: Failure in creating VP");
						pairfree(&first);
						return NULL;
					}
				}

				goto next_attr;
			} /* else it's another kind of attribute */
			/* FALL-THROUGH */

		default:
			vp->length = size;
			memcpy(vp->vp_strvalue, data, vp->length);
			break;
		}

		/*
		 *	User-Password is NUL padded to a multiple
		 *	of 16 bytes.  Let's chop it to something
		 *	more reasonable.
		 *
		 *	NOTE: This means that the User-Password
		 *	attribute CANNOT EVER have embedded zeros in it!
		 */
		switch (vp->attribute) {
		case PW_USER_PASSWORD:
			/*
			 *	If the password is exactly 16 octets,
			 *	it won't be zero-terminated.
			 */
			vp->vp_strvalue[vp->length] = '\0';
			vp->length = strlen(vp->vp_strvalue);
			break;

			/*
			 *	Ensure that the client is using the
			 *	correct challenge.  This weirdness is
			 *	to protect against against replay
			 *	attacks, where anyone observing the
			 *	CHAP exchange could pose as that user,
			 *	by simply choosing to use the same
			 *	challenge.
			 *
			 *	By using a challenge based on
			 *	information from the current session,
			 *	we can guarantee that the client is
			 *	not *choosing* a challenge.
			 *
			 *	We're a little forgiving in that we
			 *	have loose checks on the length, and
			 *	we do NOT check the Id (first octet of
			 *	the response to the challenge)
			 *
			 *	But if the client gets the challenge correct,
			 *	we're not too worried about the Id.
			 */
		case PW_CHAP_CHALLENGE:
		case PW_MSCHAP_CHALLENGE:
			if ((vp->length < 8) ||
			    (vp->length > 16)) {
				DEBUG2("  TTLS: Tunneled challenge has invalid length");
				pairfree(&first);
				pairfree(&vp);
				return NULL;

			} else {
				uint8_t	challenge[16];

				eapttls_gen_challenge(ssl, challenge,
						      sizeof(challenge));

				if (memcmp(challenge, vp->vp_octets,
					   vp->length) != 0) {
					DEBUG2("  TTLS: Tunneled challenge is incorrect");
					pairfree(&first);
					pairfree(&vp);
					return NULL;
				}
			}
			break;

		default:
			break;
		} /* switch over checking/re-writing of attributes. */

		/*
		 *	Update the list.
		 */
		*last = vp;
		last = &(vp->next);

	next_attr:
		/*
		 *	Catch non-aligned attributes.
		 */
		if (data_left == length) break;

		/*