diff options
Diffstat (limited to 'src/libcharon/plugins/dhcp/dhcp_socket.c')
| -rw-r--r-- | src/libcharon/plugins/dhcp/dhcp_socket.c | 758 |
1 files changed, 758 insertions, 0 deletions
diff --git a/src/libcharon/plugins/dhcp/dhcp_socket.c b/src/libcharon/plugins/dhcp/dhcp_socket.c new file mode 100644 index 000000000..f61b3a60e --- /dev/null +++ b/src/libcharon/plugins/dhcp/dhcp_socket.c @@ -0,0 +1,758 @@ +/* + * Copyright (C) 2010 Martin Willi + * Copyright (C) 2010 revosec AG + * + * 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 "dhcp_socket.h" + +#include <unistd.h> +#include <errno.h> +#include <string.h> +#include <netinet/in.h> +#include <netinet/ip.h> +#include <netinet/udp.h> +#include <linux/if_arp.h> +#include <linux/if_ether.h> +#include <linux/filter.h> + +#include <utils/linked_list.h> +#include <utils/identification.h> +#include <threading/mutex.h> +#include <threading/condvar.h> +#include <threading/thread.h> + +#include <daemon.h> +#include <processing/jobs/callback_job.h> + +#define DHCP_SERVER_PORT 67 +#define DHCP_CLIENT_PORT 68 +#define DHCP_TRIES 5 + +typedef struct private_dhcp_socket_t private_dhcp_socket_t; + +/** + * Private data of an dhcp_socket_t object. + */ +struct private_dhcp_socket_t { + + /** + * Public dhcp_socket_t interface. + */ + dhcp_socket_t public; + + /** + * Random number generator + */ + rng_t *rng; + + /** + * List of transactions in DISCOVER + */ + linked_list_t *discover; + + /** + * List of transactions in REQUEST + */ + linked_list_t *request; + + /** + * List of successfully completed transactions + */ + linked_list_t *completed; + + /** + * Lock for transactions + */ + mutex_t *mutex; + + /** + * Condvar to wait for transaction completion + */ + condvar_t *condvar; + + /** + * Threads waiting in condvar + */ + int waiting; + + /** + * DHCP send socket + */ + int send; + + /** + * DHCP receive socket + */ + int receive; + + /** + * Do we use per-identity or random leases (and MAC addresses) + */ + bool identity_lease; + + /** + * DHCP server address, or broadcast + */ + host_t *dst; + + /** + * Callback job receiving DHCP responses + */ + callback_job_t *job; +}; + +/** + * DHCP opcode (or BOOTP actually) + */ +typedef enum { + BOOTREQUEST = 1, + BOOTREPLY = 2, +} dhcp_opcode_t; + +/** + * Some DHCP options used + */ +typedef enum { + DHCP_DNS_SERVER = 6, + DHCP_HOST_NAME = 12, + DHCP_NBNS_SERVER = 44, + DHCP_REQUESTED_IP = 50, + DHCP_MESSAGE_TYPE = 53, + DHCP_SERVER_ID = 54, + DHCP_PARAM_REQ_LIST = 55, + DHCP_CLIENT_ID = 61, + DHCP_OPTEND = 255, +} dhcp_option_type_t; + +/** + * DHCP messages types in the DHCP_MESSAGE_TYPE option + */ +typedef enum { + DHCP_DISCOVER = 1, + DHCP_OFFER = 2, + DHCP_REQUEST = 3, + DHCP_DECLINE = 4, + DHCP_ACK = 5, + DHCP_NAK = 6, + DHCP_RELEASE = 7, + DHCP_INFORM = 8, +} dhcp_message_type_t; +/** + * DHCP option encoding, a TLV + */ +typedef struct __attribute__((packed)) { + u_int8_t type; + u_int8_t len; + char data[]; +} dhcp_option_t; + +/** + * DHCP message format, with a maximum size options buffer + */ +typedef struct __attribute__((packed)) { + u_int8_t opcode; + u_int8_t hw_type; + u_int8_t hw_addr_len; + u_int8_t hop_count; + u_int32_t transaction_id; + u_int16_t number_of_seconds; + u_int16_t flags; + u_int32_t client_address; + u_int32_t your_address; + u_int32_t server_address; + u_int32_t gateway_address; + char client_hw_addr[6]; + char client_hw_padding[10]; + char server_hostname[64]; + char boot_filename[128]; + u_int32_t magic_cookie; + char options[252]; +} dhcp_t; + +/** + * Prepare a DHCP message for a given transaction + */ +static int prepare_dhcp(private_dhcp_socket_t *this, + dhcp_transaction_t *transaction, + dhcp_message_type_t type, dhcp_t *dhcp) +{ + chunk_t chunk, broadcast = chunk_from_chars(0xFF,0xFF,0xFF,0xFF); + identification_t *identity; + dhcp_option_t *option; + int optlen = 0; + host_t *src; + u_int32_t id; + + memset(dhcp, 0, sizeof(*dhcp)); + dhcp->opcode = BOOTREQUEST; + dhcp->hw_type = ARPHRD_ETHER; + dhcp->hw_addr_len = 6; + dhcp->transaction_id = transaction->get_id(transaction); + if (chunk_equals(broadcast, this->dst->get_address(this->dst))) + { + /* TODO: send with 0.0.0.0 source address */ + } + else + { + /* act as relay agent */ + src = charon->kernel_interface->get_source_addr( + charon->kernel_interface, this->dst, NULL); + if (src) + { + memcpy(&dhcp->gateway_address, src->get_address(src).ptr, + sizeof(dhcp->gateway_address)); + src->destroy(src); + } + } + + identity = transaction->get_identity(transaction); + chunk = identity->get_encoding(identity); + /* magic bytes, a locally administered unicast MAC */ + dhcp->client_hw_addr[0] = 0x7A; + dhcp->client_hw_addr[1] = 0xA7; + /* with ID specific postfix */ + if (this->identity_lease) + { + id = htonl(chunk_hash(chunk)); + } + else + { + id = transaction->get_id(transaction); + } + memcpy(&dhcp->client_hw_addr[2], &id, sizeof(id)); + + dhcp->magic_cookie = htonl(0x63825363); + + option = (dhcp_option_t*)&dhcp->options[optlen]; + option->type = DHCP_MESSAGE_TYPE; + option->len = 1; + option->data[0] = type; + optlen += sizeof(dhcp_option_t) + option->len; + + if (identity->get_type(identity) == ID_FQDN) + { + option = (dhcp_option_t*)&dhcp->options[optlen]; + option->type = DHCP_HOST_NAME; + option->len = min(chunk.len, 64); + memcpy(option->data, chunk.ptr, option->len); + optlen += sizeof(dhcp_option_t) + option->len; + } + + option = (dhcp_option_t*)&dhcp->options[optlen]; + option->type = DHCP_CLIENT_ID; + option->len = min(chunk.len, 64); + memcpy(option->data, chunk.ptr, option->len); + optlen += sizeof(dhcp_option_t) + option->len; + + return optlen; +} + +/** + * Send a DHCP message with given options length + */ +static bool send_dhcp(private_dhcp_socket_t *this, + dhcp_transaction_t *transaction, dhcp_t *dhcp, int optlen) +{ + host_t *dst; + ssize_t len; + + dst = transaction->get_server(transaction); + if (!dst) + { + dst = this->dst; + } + len = offsetof(dhcp_t, magic_cookie) + ((optlen + 4) / 64 * 64 + 64); + return sendto(this->send, dhcp, len, 0, dst->get_sockaddr(dst), + *dst->get_sockaddr_len(dst)) == len; +} + +/** + * Send DHCP discover using a given transaction + */ +static bool discover(private_dhcp_socket_t *this, + dhcp_transaction_t *transaction) +{ + dhcp_option_t *option; + dhcp_t dhcp; + int optlen; + + optlen = prepare_dhcp(this, transaction, DHCP_DISCOVER, &dhcp); + + DBG1(DBG_CFG, "sending DHCP DISCOVER to %H", this->dst); + + option = (dhcp_option_t*)&dhcp.options[optlen]; + option->type = DHCP_PARAM_REQ_LIST; + option->len = 2; + option->data[0] = DHCP_DNS_SERVER; + option->data[1] = DHCP_NBNS_SERVER; + optlen += sizeof(dhcp_option_t) + option->len; + + dhcp.options[optlen++] = DHCP_OPTEND; + + if (!send_dhcp(this, transaction, &dhcp, optlen)) + { + DBG1(DBG_CFG, "sending DHCP DISCOVER failed: %s", strerror(errno)); + return FALSE; + } + return TRUE; +} + +/** + * Send DHCP request using a given transaction + */ +static bool request(private_dhcp_socket_t *this, + dhcp_transaction_t *transaction) +{ + dhcp_option_t *option; + dhcp_t dhcp; + host_t *offer, *server; + chunk_t chunk; + int optlen; + + optlen = prepare_dhcp(this, transaction, DHCP_REQUEST, &dhcp); + + offer = transaction->get_address(transaction); + server = transaction->get_server(transaction); + if (!offer || !server) + { + return FALSE; + } + DBG1(DBG_CFG, "sending DHCP REQUEST for %H to %H", offer, server); + + option = (dhcp_option_t*)&dhcp.options[optlen]; + option->type = DHCP_REQUESTED_IP; + option->len = 4; + chunk = offer->get_address(offer); + memcpy(option->data, chunk.ptr, min(chunk.len, option->len)); + optlen += sizeof(dhcp_option_t) + option->len; + + option = (dhcp_option_t*)&dhcp.options[optlen]; + option->type = DHCP_SERVER_ID; + option->len = 4; + chunk = server->get_address(server); + memcpy(option->data, chunk.ptr, min(chunk.len, option->len)); + optlen += sizeof(dhcp_option_t) + option->len; + + option = (dhcp_option_t*)&dhcp.options[optlen]; + option->type = DHCP_PARAM_REQ_LIST; + option->len = 2; + option->data[0] = DHCP_DNS_SERVER; + option->data[1] = DHCP_NBNS_SERVER; + optlen += sizeof(dhcp_option_t) + option->len; + + dhcp.options[optlen++] = DHCP_OPTEND; + + if (!send_dhcp(this, transaction, &dhcp, optlen)) + { + DBG1(DBG_CFG, "sending DHCP REQUEST failed: %s", strerror(errno)); + return FALSE; + } + return TRUE; +} + +METHOD(dhcp_socket_t, enroll, dhcp_transaction_t*, + private_dhcp_socket_t *this, identification_t *identity) +{ + dhcp_transaction_t *transaction; + u_int32_t id; + int try; + + this->rng->get_bytes(this->rng, sizeof(id), (u_int8_t*)&id); + transaction = dhcp_transaction_create(id, identity); + + this->mutex->lock(this->mutex); + this->discover->insert_last(this->discover, transaction); + try = 1; + while (try <= DHCP_TRIES && discover(this, transaction)) + { + if (!this->condvar->timed_wait(this->condvar, this->mutex, 1000 * try) && + this->request->find_first(this->request, NULL, + (void**)&transaction) == SUCCESS) + { + break; + } + try++; + } + if (this->discover->remove(this->discover, transaction, NULL)) + { /* no OFFER received */ + this->mutex->unlock(this->mutex); + transaction->destroy(transaction); + DBG1(DBG_CFG, "DHCP DISCOVER timed out"); + return NULL; + } + + try = 1; + while (try <= DHCP_TRIES && request(this, transaction)) + { + if (!this->condvar->timed_wait(this->condvar, this->mutex, 1000 * try) && + this->completed->remove(this->completed, transaction, NULL)) + { + break; + } + try++; + } + if (this->request->remove(this->request, transaction, NULL)) + { /* no ACK received */ + this->mutex->unlock(this->mutex); + transaction->destroy(transaction); + DBG1(DBG_CFG, "DHCP REQUEST timed out"); + return NULL; + } + this->mutex->unlock(this->mutex); + + return transaction; +} + +METHOD(dhcp_socket_t, release, void, + private_dhcp_socket_t *this, dhcp_transaction_t *transaction) +{ + dhcp_option_t *option; + dhcp_t dhcp; + host_t *release, *server; + chunk_t chunk; + int optlen; + + optlen = prepare_dhcp(this, transaction, DHCP_RELEASE, &dhcp); + + release = transaction->get_address(transaction); + server = transaction->get_server(transaction); + if (!release || !server) + { + return; + } + DBG1(DBG_CFG, "sending DHCP RELEASE for %H to %H", release, server); + + chunk = release->get_address(release); + memcpy(&dhcp.client_address, chunk.ptr, + min(chunk.len, sizeof(dhcp.client_address))); + + option = (dhcp_option_t*)&dhcp.options[optlen]; + option->type = DHCP_SERVER_ID; + option->len = 4; + chunk = server->get_address(server); + memcpy(option->data, chunk.ptr, min(chunk.len, option->len)); + optlen += sizeof(dhcp_option_t) + option->len; + + dhcp.options[optlen++] = DHCP_OPTEND; + + if (!send_dhcp(this, transaction, &dhcp, optlen)) + { + DBG1(DBG_CFG, "sending DHCP RELEASE failed: %s", strerror(errno)); + } +} + +/** + * Handle a DHCP OFFER + */ +static void handle_offer(private_dhcp_socket_t *this, dhcp_t *dhcp, int optlen) +{ + dhcp_transaction_t *transaction = NULL; + enumerator_t *enumerator; + host_t *offer, *server; + + offer = host_create_from_chunk(AF_INET, + chunk_from_thing(dhcp->your_address), 0); + server = host_create_from_chunk(AF_INET, + chunk_from_thing(dhcp->server_address), DHCP_SERVER_PORT); + + this->mutex->lock(this->mutex); + enumerator = this->discover->create_enumerator(this->discover); + while (enumerator->enumerate(enumerator, &transaction)) + { + if (transaction->get_id(transaction) == dhcp->transaction_id) + { + DBG1(DBG_CFG, "received DHCP OFFER %H from %H", offer, server); + this->discover->remove_at(this->discover, enumerator); + this->request->insert_last(this->request, transaction); + transaction->set_address(transaction, offer->clone(offer)); + transaction->set_server(transaction, server->clone(server)); + break; + } + } + enumerator->destroy(enumerator); + + if (transaction) + { + int optsize, optpos = 0, pos; + dhcp_option_t *option; + + while (optlen > sizeof(dhcp_option_t)) + { + option = (dhcp_option_t*)&dhcp->options[optpos]; + optsize = sizeof(dhcp_option_t) + option->len; + if (option->type == DHCP_OPTEND || optlen < optsize) + { + break; + } + if (option->type == DHCP_DNS_SERVER || + option->type == DHCP_NBNS_SERVER) + { + for (pos = 0; pos + 4 <= option->len; pos += 4) + { + transaction->add_attribute(transaction, option->type == + DHCP_DNS_SERVER ? INTERNAL_IP4_DNS : INTERNAL_IP4_NBNS, + chunk_create((char*)&option->data[pos], 4)); + } + } + optlen -= optsize; + optpos += optsize; + } + } + this->mutex->unlock(this->mutex); + this->condvar->broadcast(this->condvar); + offer->destroy(offer); + server->destroy(server); +} + +/** + * Handle a DHCP ACK + */ +static void handle_ack(private_dhcp_socket_t *this, dhcp_t *dhcp, int optlen) +{ + dhcp_transaction_t *transaction; + enumerator_t *enumerator; + host_t *offer; + + offer = host_create_from_chunk(AF_INET, + chunk_from_thing(dhcp->your_address), 0); + + this->mutex->lock(this->mutex); + enumerator = this->request->create_enumerator(this->request); + while (enumerator->enumerate(enumerator, &transaction)) + { + if (transaction->get_id(transaction) == dhcp->transaction_id) + { + DBG1(DBG_CFG, "received DHCP ACK for %H", offer); + this->request->remove_at(this->request, enumerator); + this->completed->insert_last(this->completed, transaction); + break; + } + } + enumerator->destroy(enumerator); + this->mutex->unlock(this->mutex); + this->condvar->broadcast(this->condvar); + offer->destroy(offer); +} + +/** + * Receive DHCP responses + */ +static job_requeue_t receive_dhcp(private_dhcp_socket_t *this) +{ + struct sockaddr_ll addr; + socklen_t addr_len = sizeof(addr); + struct __attribute__((packed)) { + struct iphdr ip; + struct udphdr udp; + dhcp_t dhcp; + } packet; + int oldstate, optlen, origoptlen, optsize, optpos = 0; + ssize_t len; + dhcp_option_t *option; + + oldstate = thread_cancelability(TRUE); + len = recvfrom(this->receive, &packet, sizeof(packet), 0, + (struct sockaddr*)&addr, &addr_len); + thread_cancelability(oldstate); + + if (len >= sizeof(struct iphdr) + sizeof(struct udphdr) + + offsetof(dhcp_t, options)) + { + origoptlen = optlen = len - sizeof(struct iphdr) + + sizeof(struct udphdr) + offsetof(dhcp_t, options); + while (optlen > sizeof(dhcp_option_t)) + { + option = (dhcp_option_t*)&packet.dhcp.options[optpos]; + optsize = sizeof(dhcp_option_t) + option->len; + if (option->type == DHCP_OPTEND || optlen < optsize) + { + break; + } + if (option->type == DHCP_MESSAGE_TYPE && option->len == 1) + { + switch (option->data[0]) + { + case DHCP_OFFER: + handle_offer(this, &packet.dhcp, origoptlen); + break; + case DHCP_ACK: + handle_ack(this, &packet.dhcp, origoptlen); + default: + break; + } + break; + } + optlen -= optsize; + optpos += optsize; + } + } + return JOB_REQUEUE_DIRECT; +} + +METHOD(dhcp_socket_t, destroy, void, + private_dhcp_socket_t *this) +{ + if (this->job) + { + this->job->cancel(this->job); + } + while (this->waiting) + { + this->condvar->signal(this->condvar); + } + if (this->send > 0) + { + close(this->send); + } + if (this->receive > 0) + { + close(this->receive); + } + this->mutex->destroy(this->mutex); + this->condvar->destroy(this->condvar); + this->discover->destroy_offset(this->discover, + offsetof(dhcp_transaction_t, destroy)); + this->request->destroy_offset(this->request, + offsetof(dhcp_transaction_t, destroy)); + this->completed->destroy_offset(this->completed, + offsetof(dhcp_transaction_t, destroy)); + DESTROY_IF(this->rng); + DESTROY_IF(this->dst); + free(this); +} + +/** + * See header + */ +dhcp_socket_t *dhcp_socket_create() +{ + private_dhcp_socket_t *this; + struct sockaddr_in src; + int on = 1; + struct sock_filter dhcp_filter_code[] = { + BPF_STMT(BPF_LD+BPF_B+BPF_ABS, + offsetof(struct iphdr, protocol)), + BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, IPPROTO_UDP, 0, 16), + BPF_STMT(BPF_LD+BPF_H+BPF_ABS, sizeof(struct iphdr) + + offsetof(struct udphdr, source)), + BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, DHCP_SERVER_PORT, 0, 14), + BPF_STMT(BPF_LD+BPF_H+BPF_ABS, sizeof(struct iphdr) + + offsetof(struct udphdr, dest)), + BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, DHCP_CLIENT_PORT, 0, 2), + BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, DHCP_SERVER_PORT, 0, 1), + BPF_JUMP(BPF_JMP+BPF_JA, 0, 0, 10), + BPF_STMT(BPF_LD+BPF_B+BPF_ABS, sizeof(struct iphdr) + + sizeof(struct udphdr) + offsetof(dhcp_t, opcode)), + BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, BOOTREPLY, 0, 8), + BPF_STMT(BPF_LD+BPF_B+BPF_ABS, sizeof(struct iphdr) + + sizeof(struct udphdr) + offsetof(dhcp_t, hw_type)), + BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, ARPHRD_ETHER, 0, 6), + BPF_STMT(BPF_LD+BPF_B+BPF_ABS, sizeof(struct iphdr) + + sizeof(struct udphdr) + offsetof(dhcp_t, hw_addr_len)), + BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, 6, 0, 4), + BPF_STMT(BPF_LD+BPF_W+BPF_ABS, sizeof(struct iphdr) + + sizeof(struct udphdr) + offsetof(dhcp_t, magic_cookie)), + BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, 0x63825363, 0, 2), + BPF_STMT(BPF_LD+BPF_W+BPF_LEN, 0), + BPF_STMT(BPF_RET+BPF_A, 0), + BPF_STMT(BPF_RET+BPF_K, 0), + }; + struct sock_fprog dhcp_filter = { + sizeof(dhcp_filter_code) / sizeof(struct sock_filter), + dhcp_filter_code, + }; + + INIT(this, + .public = { + .enroll = _enroll, + .release = _release, + .destroy = _destroy, + }, + .rng = lib->crypto->create_rng(lib->crypto, RNG_WEAK), + .mutex = mutex_create(MUTEX_TYPE_DEFAULT), + .condvar = condvar_create(CONDVAR_TYPE_DEFAULT), + .discover = linked_list_create(), + .request = linked_list_create(), + .completed = linked_list_create(), + ); + + if (!this->rng) + { + DBG1(DBG_CFG, "unable to create RNG"); + destroy(this); + return NULL; + } + this->identity_lease = lib->settings->get_bool(lib->settings, + "charon.plugins.dhcp.identity_lease", FALSE); + this->dst = host_create_from_string(lib->settings->get_str(lib->settings, + "charon.plugins.dhcp.server", "255.255.255.255"), + DHCP_SERVER_PORT); + if (!this->dst) + { + DBG1(DBG_CFG, "configured DHCP server address invalid"); + destroy(this); + return NULL; + } + + this->send = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP); + if (this->send == -1) + { + DBG1(DBG_CFG, "unable to create DHCP send socket: %s", strerror(errno)); + destroy(this); + return NULL; + } + if (setsockopt(this->send, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)) == -1) + { + DBG1(DBG_CFG, "unable to reuse DHCP socket address: %s", strerror(errno)); + destroy(this); + return NULL; + } + if (setsockopt(this->send, SOL_SOCKET, SO_BROADCAST, &on, sizeof(on)) == -1) + { + DBG1(DBG_CFG, "unable to broadcast on DHCP socket: %s", strerror(errno)); + destroy(this); + return NULL; + } + src.sin_family = AF_INET; + src.sin_port = htons(DHCP_CLIENT_PORT); + src.sin_addr.s_addr = INADDR_ANY; + if (bind(this->send, (struct sockaddr*)&src, sizeof(src)) == -1) + { + DBG1(DBG_CFG, "unable to bind DHCP send socket: %s", strerror(errno)); + destroy(this); + return NULL; + } + + this->receive = socket(AF_PACKET, SOCK_DGRAM, htons(ETH_P_IP)); + if (this->receive == -1) + { + DBG1(DBG_NET, "opening DHCP receive socket failed: %s", strerror(errno)); + destroy(this); + return NULL; + } + if (setsockopt(this->receive, SOL_SOCKET, SO_ATTACH_FILTER, + &dhcp_filter, sizeof(dhcp_filter)) < 0) + { + DBG1(DBG_CFG, "installing DHCP socket filter failed: %s", + strerror(errno)); + destroy(this); + return NULL; + } + + this->job = callback_job_create((callback_job_cb_t)receive_dhcp, + this, NULL, NULL); + charon->processor->queue_job(charon->processor, (job_t*)this->job); + + return &this->public; +} + |