diff options
Diffstat (limited to 'src/libcharon/plugins/eap_radius/radius_client.c')
| -rw-r--r-- | src/libcharon/plugins/eap_radius/radius_client.c | 495 |
1 files changed, 495 insertions, 0 deletions
diff --git a/src/libcharon/plugins/eap_radius/radius_client.c b/src/libcharon/plugins/eap_radius/radius_client.c new file mode 100644 index 000000000..1d1f21742 --- /dev/null +++ b/src/libcharon/plugins/eap_radius/radius_client.c @@ -0,0 +1,495 @@ +/* + * Copyright (C) 2009 Martin Willi + * Hochschule fuer Technik Rapperswil + * + * 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. See <http://www.fsf.org/copyleft/gpl.txt>. + * + * 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. + */ + +#include "radius_client.h" + +#include <unistd.h> +#include <errno.h> + +#include <daemon.h> +#include <utils/host.h> +#include <utils/linked_list.h> +#include <threading/condvar.h> +#include <threading/mutex.h> + +/** + * Default RADIUS server port, when not configured + */ +#define RADIUS_PORT 1812 + +/** + * Vendor-Id of Microsoft specific attributes + */ +#define VENDOR_ID_MICROSOFT 311 + +/** + * Microsoft specific vendor attributes + */ +#define MS_MPPE_SEND_KEY 16 +#define MS_MPPE_RECV_KEY 17 + +typedef struct private_radius_client_t private_radius_client_t; + +typedef struct entry_t entry_t; + +/** + * A socket pool entry. + */ +struct entry_t { + /** socket file descriptor */ + int fd; + /** current RADIUS identifier */ + u_int8_t identifier; + /** hasher to use for response verification */ + hasher_t *hasher; + /** HMAC-MD5 signer to build Message-Authenticator attribute */ + signer_t *signer; + /** random number generator for RADIUS request authenticator */ + rng_t *rng; +}; + +/** + * Private data of an radius_client_t object. + */ +struct private_radius_client_t { + + /** + * Public radius_client_t interface. + */ + radius_client_t public; + + /** + * RADIUS servers State attribute + */ + chunk_t state; +}; + +/** + * Global list of radius sockets, contains entry_t's + */ +static linked_list_t *sockets; + +/** + * mutex to lock sockets list + */ +static mutex_t *mutex; + +/** + * condvar to wait for sockets + */ +static condvar_t *condvar; + +/** + * RADIUS secret + */ +static chunk_t secret; + +/** + * NAS-Identifier + */ +static chunk_t nas_identifier; + +/** + * Clean up socket list + */ +void radius_client_cleanup() +{ + entry_t *entry; + + mutex->destroy(mutex); + condvar->destroy(condvar); + while (sockets->remove_last(sockets, (void**)&entry) == SUCCESS) + { + entry->rng->destroy(entry->rng); + entry->hasher->destroy(entry->hasher); + entry->signer->destroy(entry->signer); + close(entry->fd); + free(entry); + } + sockets->destroy(sockets); +} + +/** + * Initialize the socket list + */ +bool radius_client_init() +{ + int i, count, fd; + u_int16_t port; + entry_t *entry; + host_t *host; + char *server; + + nas_identifier.ptr = lib->settings->get_str(lib->settings, + "charon.plugins.eap-radius.nas_identifier", "strongSwan"); + nas_identifier.len = strlen(nas_identifier.ptr); + + secret.ptr = lib->settings->get_str(lib->settings, + "charon.plugins.eap-radius.secret", NULL); + if (!secret.ptr) + { + DBG1(DBG_CFG, "no RADUIS secret defined"); + return FALSE; + } + secret.len = strlen(secret.ptr); + server = lib->settings->get_str(lib->settings, + "charon.plugins.eap-radius.server", NULL); + if (!server) + { + DBG1(DBG_CFG, "no RADUIS server defined"); + return FALSE; + } + port = lib->settings->get_int(lib->settings, + "charon.plugins.eap-radius.port", RADIUS_PORT); + host = host_create_from_dns(server, 0, port); + if (!host) + { + return FALSE; + } + count = lib->settings->get_int(lib->settings, + "charon.plugins.eap-radius.sockets", 1); + + sockets = linked_list_create(); + mutex = mutex_create(MUTEX_TYPE_DEFAULT); + condvar = condvar_create(CONDVAR_TYPE_DEFAULT); + for (i = 0; i < count; i++) + { + fd = socket(host->get_family(host), SOCK_DGRAM, IPPROTO_UDP); + if (fd < 0) + { + DBG1(DBG_CFG, "opening RADIUS socket failed"); + host->destroy(host); + radius_client_cleanup(); + return FALSE; + } + if (connect(fd, host->get_sockaddr(host), + *host->get_sockaddr_len(host)) < 0) + { + DBG1(DBG_CFG, "connecting RADIUS socket failed"); + host->destroy(host); + radius_client_cleanup(); + return FALSE; + } + entry = malloc_thing(entry_t); + entry->fd = fd; + /* we use per-socket crypto elements: this reduces overhead, but + * is still thread-save. */ + entry->hasher = lib->crypto->create_hasher(lib->crypto, HASH_MD5); + entry->signer = lib->crypto->create_signer(lib->crypto, AUTH_HMAC_MD5_128); + entry->rng = lib->crypto->create_rng(lib->crypto, RNG_WEAK); + if (!entry->hasher || !entry->signer || !entry->rng) + { + DBG1(DBG_CFG, "RADIUS initialization failed, HMAC/MD5/RNG required"); + DESTROY_IF(entry->hasher); + DESTROY_IF(entry->signer); + DESTROY_IF(entry->rng); + free(entry); + host->destroy(host); + radius_client_cleanup(); + return FALSE; + } + entry->signer->set_key(entry->signer, secret); + /* we use a random identifier, helps if we restart often (testing) */ + entry->identifier = random(); + sockets->insert_last(sockets, entry); + } + host->destroy(host); + return TRUE; +} + +/** + * Get a socket from the pool, block if none available + */ +static entry_t* get_socket() +{ + entry_t *entry; + + mutex->lock(mutex); + while (sockets->remove_first(sockets, (void**)&entry) != SUCCESS) + { + condvar->wait(condvar, mutex); + } + mutex->unlock(mutex); + return entry; +} + +/** + * Release a socket to the pool + */ +static void put_socket(entry_t *entry) +{ + mutex->lock(mutex); + sockets->insert_last(sockets, entry); + mutex->unlock(mutex); + condvar->signal(condvar); +} + +/** + * Save the state attribute to include in further request + */ +static void save_state(private_radius_client_t *this, radius_message_t *msg) +{ + enumerator_t *enumerator; + int type; + chunk_t data; + + enumerator = msg->create_enumerator(msg); + while (enumerator->enumerate(enumerator, &type, &data)) + { + if (type == RAT_STATE) + { + free(this->state.ptr); + this->state = chunk_clone(data); + enumerator->destroy(enumerator); + return; + } + } + enumerator->destroy(enumerator); + /* no state attribute found, remove state */ + chunk_free(&this->state); +} + +/** + * Implementation of radius_client_t.request + */ +static radius_message_t* request(private_radius_client_t *this, + radius_message_t *req) +{ + char virtual[] = {0x00,0x00,0x00,0x05}; + entry_t *socket; + chunk_t data; + int i; + + socket = get_socket(); + + /* set Message Identifier */ + req->set_identifier(req, socket->identifier++); + /* we add the "Virtual" NAS-Port-Type, as we SHOULD include one */ + req->add(req, RAT_NAS_PORT_TYPE, chunk_create(virtual, sizeof(virtual))); + /* add our NAS-Identifier */ + req->add(req, RAT_NAS_IDENTIFIER, nas_identifier); + /* add State attribute, if server sent one */ + if (this->state.ptr) + { + req->add(req, RAT_STATE, this->state); + } + /* sign the request */ + req->sign(req, socket->rng, socket->signer); + + data = req->get_encoding(req); + /* timeout after 2, 3, 4, 5 seconds */ + for (i = 2; i <= 5; i++) + { + radius_message_t *response; + bool retransmit = FALSE; + struct timeval tv; + char buf[4096]; + fd_set fds; + int res; + + if (send(socket->fd, data.ptr, data.len, 0) != data.len) + { + DBG1(DBG_CFG, "sending RADIUS message failed: %s", strerror(errno)); + put_socket(socket); + return NULL; + } + tv.tv_sec = i; + tv.tv_usec = 0; + + while (TRUE) + { + FD_ZERO(&fds); + FD_SET(socket->fd, &fds); + res = select(socket->fd + 1, &fds, NULL, NULL, &tv); + /* TODO: updated tv to time not waited. Linux does this for us. */ + if (res < 0) + { /* failed */ + DBG1(DBG_CFG, "waiting for RADIUS message failed: %s", + strerror(errno)); + break; + } + if (res == 0) + { /* timeout */ + DBG1(DBG_CFG, "retransmitting RADIUS message"); + retransmit = TRUE; + break; + } + res = recv(socket->fd, buf, sizeof(buf), MSG_DONTWAIT); + if (res <= 0) + { + DBG1(DBG_CFG, "receiving RADIUS message failed: %s", + strerror(errno)); + break; + } + response = radius_message_parse_response(chunk_create(buf, res)); + if (response) + { + if (response->verify(response, req->get_authenticator(req), + secret, socket->hasher, socket->signer)) + { + save_state(this, response); + put_socket(socket); + return response; + } + response->destroy(response); + } + DBG1(DBG_CFG, "received invalid RADIUS message, ignored"); + } + if (!retransmit) + { + break; + } + } + DBG1(DBG_CFG, "RADIUS server is not responding"); + put_socket(socket); + charon->bus->alert(charon->bus, ALERT_RADIUS_NOT_RESPONDING); + return NULL; +} + +/** + * Decrypt a MS-MPPE-Send/Recv-Key + */ +static chunk_t decrypt_mppe_key(private_radius_client_t *this, u_int16_t salt, + chunk_t C, radius_message_t *request) +{ + chunk_t A, R, P, seed; + u_char *c, *p; + hasher_t *hasher; + + /** + * From RFC2548 (encryption): + * b(1) = MD5(S + R + A) c(1) = p(1) xor b(1) C = c(1) + * b(2) = MD5(S + c(1)) c(2) = p(2) xor b(2) C = C + c(2) + * . . . + * b(i) = MD5(S + c(i-1)) c(i) = p(i) xor b(i) C = C + c(i) + */ + + if (C.len % HASH_SIZE_MD5 || C.len < HASH_SIZE_MD5) + { + return chunk_empty; + } + + hasher = lib->crypto->create_hasher(lib->crypto, HASH_MD5); + if (!hasher) + { + return chunk_empty; + } + + A = chunk_create((u_char*)&salt, sizeof(salt)); + R = chunk_create(request->get_authenticator(request), HASH_SIZE_MD5); + P = chunk_alloca(C.len); + p = P.ptr; + c = C.ptr; + + seed = chunk_cata("cc", R, A); + + while (c < C.ptr + C.len) + { + /* b(i) = MD5(S + c(i-1)) */ + hasher->get_hash(hasher, secret, NULL); + hasher->get_hash(hasher, seed, p); + + /* p(i) = b(i) xor c(1) */ + memxor(p, c, HASH_SIZE_MD5); + + /* prepare next round */ + seed = chunk_create(c, HASH_SIZE_MD5); + c += HASH_SIZE_MD5; + p += HASH_SIZE_MD5; + } + hasher->destroy(hasher); + + /* remove truncation, first byte is key length */ + if (*P.ptr >= P.len) + { /* decryption failed? */ + return chunk_empty; + } + return chunk_clone(chunk_create(P.ptr + 1, *P.ptr)); +} + +/** + * Implementation of radius_client_t.decrypt_msk + */ +static chunk_t decrypt_msk(private_radius_client_t *this, + radius_message_t *response, radius_message_t *request) +{ + struct { + u_int32_t id; + u_int8_t type; + u_int8_t length; + u_int16_t salt; + u_int8_t key[]; + } __attribute__((packed)) *mppe_key; + enumerator_t *enumerator; + chunk_t data, send = chunk_empty, recv = chunk_empty; + int type; + + enumerator = response->create_enumerator(response); + while (enumerator->enumerate(enumerator, &type, &data)) + { + if (type == RAT_VENDOR_SPECIFIC && + data.len > sizeof(*mppe_key)) + { + mppe_key = (void*)data.ptr; + if (ntohl(mppe_key->id) == VENDOR_ID_MICROSOFT && + mppe_key->length == data.len - sizeof(mppe_key->id)) + { + data = chunk_create(mppe_key->key, data.len - sizeof(*mppe_key)); + if (mppe_key->type == MS_MPPE_SEND_KEY) + { + send = decrypt_mppe_key(this, mppe_key->salt, data, request); + } + if (mppe_key->type == MS_MPPE_RECV_KEY) + { + recv = decrypt_mppe_key(this, mppe_key->salt, data, request); + } + } + } + } + enumerator->destroy(enumerator); + if (send.ptr && recv.ptr) + { + return chunk_cat("mm", recv, send); + } + chunk_clear(&send); + chunk_clear(&recv); + return chunk_empty; +} + +/** + * Implementation of radius_client_t.destroy. + */ +static void destroy(private_radius_client_t *this) +{ + free(this->state.ptr); + free(this); +} + +/** + * See header + */ +radius_client_t *radius_client_create() +{ + private_radius_client_t *this = malloc_thing(private_radius_client_t); + + this->public.request = (radius_message_t*(*)(radius_client_t*, radius_message_t *msg))request; + this->public.decrypt_msk = (chunk_t(*)(radius_client_t*, radius_message_t *, radius_message_t *))decrypt_msk; + this->public.destroy = (void(*)(radius_client_t*))destroy; + + this->state = chunk_empty; + + return &this->public; +} + |