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-rw-r--r--src/libsystemd-network/dhcp-network.c269
1 files changed, 269 insertions, 0 deletions
diff --git a/src/libsystemd-network/dhcp-network.c b/src/libsystemd-network/dhcp-network.c
new file mode 100644
index 0000000..0ee977a
--- /dev/null
+++ b/src/libsystemd-network/dhcp-network.c
@@ -0,0 +1,269 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/***
+ Copyright © 2013 Intel Corporation. All rights reserved.
+***/
+
+#include <errno.h>
+#include <net/ethernet.h>
+#include <net/if.h>
+#include <net/if_arp.h>
+#include <stdio.h>
+#include <string.h>
+#include <linux/filter.h>
+#include <linux/if_infiniband.h>
+#include <linux/if_packet.h>
+
+#include "dhcp-internal.h"
+#include "fd-util.h"
+#include "socket-util.h"
+#include "unaligned.h"
+
+static int _bind_raw_socket(
+ int ifindex,
+ union sockaddr_union *link,
+ uint32_t xid,
+ const struct hw_addr_data *hw_addr,
+ const struct hw_addr_data *bcast_addr,
+ uint16_t arp_type,
+ uint16_t port) {
+
+ assert(ifindex > 0);
+ assert(link);
+ assert(hw_addr);
+ assert(bcast_addr);
+ assert(IN_SET(arp_type, ARPHRD_ETHER, ARPHRD_INFINIBAND));
+
+ switch (arp_type) {
+ case ARPHRD_ETHER:
+ assert(hw_addr->length == ETH_ALEN);
+ assert(bcast_addr->length == ETH_ALEN);
+ break;
+ case ARPHRD_INFINIBAND:
+ assert(hw_addr->length == 0);
+ assert(bcast_addr->length == INFINIBAND_ALEN);
+ break;
+ default:
+ assert_not_reached();
+ }
+
+ struct sock_filter filter[] = {
+ BPF_STMT(BPF_LD + BPF_W + BPF_LEN, 0), /* A <- packet length */
+ BPF_JUMP(BPF_JMP + BPF_JGE + BPF_K, sizeof(DHCPPacket), 1, 0), /* packet >= DHCPPacket ? */
+ BPF_STMT(BPF_RET + BPF_K, 0), /* ignore */
+ BPF_STMT(BPF_LD + BPF_B + BPF_ABS, offsetof(DHCPPacket, ip.protocol)), /* A <- IP protocol */
+ BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, IPPROTO_UDP, 1, 0), /* IP protocol == UDP ? */
+ BPF_STMT(BPF_RET + BPF_K, 0), /* ignore */
+ BPF_STMT(BPF_LD + BPF_B + BPF_ABS, offsetof(DHCPPacket, ip.frag_off)), /* A <- Flags */
+ BPF_STMT(BPF_ALU + BPF_AND + BPF_K, 0x20), /* A <- A & 0x20 (More Fragments bit) */
+ BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, 0, 1, 0), /* A == 0 ? */
+ BPF_STMT(BPF_RET + BPF_K, 0), /* ignore */
+ BPF_STMT(BPF_LD + BPF_H + BPF_ABS, offsetof(DHCPPacket, ip.frag_off)), /* A <- Flags + Fragment offset */
+ BPF_STMT(BPF_ALU + BPF_AND + BPF_K, 0x1fff), /* A <- A & 0x1fff (Fragment offset) */
+ BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, 0, 1, 0), /* A == 0 ? */
+ BPF_STMT(BPF_RET + BPF_K, 0), /* ignore */
+ BPF_STMT(BPF_LD + BPF_H + BPF_ABS, offsetof(DHCPPacket, udp.dest)), /* A <- UDP destination port */
+ BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, port, 1, 0), /* UDP destination port == DHCP client port ? */
+ BPF_STMT(BPF_RET + BPF_K, 0), /* ignore */
+ BPF_STMT(BPF_LD + BPF_B + BPF_ABS, offsetof(DHCPPacket, dhcp.op)), /* A <- DHCP op */
+ BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, BOOTREPLY, 1, 0), /* op == BOOTREPLY ? */
+ BPF_STMT(BPF_RET + BPF_K, 0), /* ignore */
+ BPF_STMT(BPF_LD + BPF_B + BPF_ABS, offsetof(DHCPPacket, dhcp.htype)), /* A <- DHCP header type */
+ BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, arp_type, 1, 0), /* header type == arp_type ? */
+ BPF_STMT(BPF_RET + BPF_K, 0), /* ignore */
+ BPF_STMT(BPF_LD + BPF_W + BPF_ABS, offsetof(DHCPPacket, dhcp.xid)), /* A <- client identifier */
+ BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, xid, 1, 0), /* client identifier == xid ? */
+ BPF_STMT(BPF_RET + BPF_K, 0), /* ignore */
+ BPF_STMT(BPF_LD + BPF_B + BPF_ABS, offsetof(DHCPPacket, dhcp.hlen)), /* A <- MAC address length */
+ BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, (uint8_t) hw_addr->length, 1, 0), /* address length == hw_addr->length ? */
+ BPF_STMT(BPF_RET + BPF_K, 0), /* ignore */
+
+ /* We only support MAC address length to be either 0 or 6 (ETH_ALEN). Optionally
+ * compare chaddr for ETH_ALEN bytes. */
+ BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ETH_ALEN, 0, 8), /* A (the MAC address length) == ETH_ALEN ? */
+ BPF_STMT(BPF_LDX + BPF_IMM, unaligned_read_be32(hw_addr->bytes)), /* X <- 4 bytes of client's MAC */
+ BPF_STMT(BPF_LD + BPF_W + BPF_ABS, offsetof(DHCPPacket, dhcp.chaddr)), /* A <- 4 bytes of MAC from dhcp.chaddr */
+ BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_X, 0, 1, 0), /* A == X ? */
+ BPF_STMT(BPF_RET + BPF_K, 0), /* ignore */
+ BPF_STMT(BPF_LDX + BPF_IMM, unaligned_read_be16(hw_addr->bytes + 4)), /* X <- remainder of client's MAC */
+ BPF_STMT(BPF_LD + BPF_H + BPF_ABS, offsetof(DHCPPacket, dhcp.chaddr) + 4), /* A <- remainder of MAC from dhcp.chaddr */
+ BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_X, 0, 1, 0), /* A == X ? */
+ BPF_STMT(BPF_RET + BPF_K, 0), /* ignore */
+
+ BPF_STMT(BPF_LD + BPF_W + BPF_ABS, offsetof(DHCPPacket, dhcp.magic)), /* A <- DHCP magic cookie */
+ BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, DHCP_MAGIC_COOKIE, 1, 0), /* cookie == DHCP magic cookie ? */
+ BPF_STMT(BPF_RET + BPF_K, 0), /* ignore */
+ BPF_STMT(BPF_RET + BPF_K, UINT32_MAX), /* accept */
+ };
+ struct sock_fprog fprog = {
+ .len = ELEMENTSOF(filter),
+ .filter = filter
+ };
+ _cleanup_close_ int s = -1;
+ int r;
+
+ s = socket(AF_PACKET, SOCK_DGRAM | SOCK_CLOEXEC | SOCK_NONBLOCK, 0);
+ if (s < 0)
+ return -errno;
+
+ r = setsockopt_int(s, SOL_PACKET, PACKET_AUXDATA, true);
+ if (r < 0)
+ return r;
+
+ r = setsockopt(s, SOL_SOCKET, SO_ATTACH_FILTER, &fprog, sizeof(fprog));
+ if (r < 0)
+ return -errno;
+
+ link->ll = (struct sockaddr_ll) {
+ .sll_family = AF_PACKET,
+ .sll_protocol = htobe16(ETH_P_IP),
+ .sll_ifindex = ifindex,
+ .sll_hatype = htobe16(arp_type),
+ .sll_halen = bcast_addr->length,
+ };
+ /* We may overflow link->ll. link->ll_buffer ensures we have enough space. */
+ memcpy(link->ll.sll_addr, bcast_addr->bytes, bcast_addr->length);
+
+ r = bind(s, &link->sa, SOCKADDR_LL_LEN(link->ll));
+ if (r < 0)
+ return -errno;
+
+ return TAKE_FD(s);
+}
+
+int dhcp_network_bind_raw_socket(
+ int ifindex,
+ union sockaddr_union *link,
+ uint32_t xid,
+ const struct hw_addr_data *hw_addr,
+ const struct hw_addr_data *bcast_addr,
+ uint16_t arp_type,
+ uint16_t port) {
+
+ static struct hw_addr_data default_eth_bcast = {
+ .length = ETH_ALEN,
+ .ether = {{ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff }},
+ }, default_ib_bcast = {
+ .length = INFINIBAND_ALEN,
+ .infiniband = {
+ 0x00, 0xff, 0xff, 0xff, 0xff, 0x12, 0x40, 0x1b,
+ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+ 0xff, 0xff, 0xff, 0xff
+ },
+ };
+
+ assert(ifindex > 0);
+ assert(link);
+ assert(hw_addr);
+
+ switch (arp_type) {
+ case ARPHRD_ETHER:
+ return _bind_raw_socket(ifindex, link, xid,
+ hw_addr,
+ (bcast_addr && !hw_addr_is_null(bcast_addr)) ? bcast_addr : &default_eth_bcast,
+ arp_type, port);
+
+ case ARPHRD_INFINIBAND:
+ return _bind_raw_socket(ifindex, link, xid,
+ &HW_ADDR_NULL,
+ (bcast_addr && !hw_addr_is_null(bcast_addr)) ? bcast_addr : &default_ib_bcast,
+ arp_type, port);
+ default:
+ return -EINVAL;
+ }
+}
+
+int dhcp_network_bind_udp_socket(int ifindex, be32_t address, uint16_t port, int ip_service_type) {
+ union sockaddr_union src = {
+ .in.sin_family = AF_INET,
+ .in.sin_port = htobe16(port),
+ .in.sin_addr.s_addr = address,
+ };
+ _cleanup_close_ int s = -1;
+ int r;
+
+ s = socket(AF_INET, SOCK_DGRAM | SOCK_CLOEXEC | SOCK_NONBLOCK, 0);
+ if (s < 0)
+ return -errno;
+
+ if (ip_service_type >= 0)
+ r = setsockopt_int(s, IPPROTO_IP, IP_TOS, ip_service_type);
+ else
+ r = setsockopt_int(s, IPPROTO_IP, IP_TOS, IPTOS_CLASS_CS6);
+ if (r < 0)
+ return r;
+
+ r = setsockopt_int(s, SOL_SOCKET, SO_REUSEADDR, true);
+ if (r < 0)
+ return r;
+
+ if (ifindex > 0) {
+ r = socket_bind_to_ifindex(s, ifindex);
+ if (r < 0)
+ return r;
+ }
+
+ if (port == DHCP_PORT_SERVER) {
+ r = setsockopt_int(s, SOL_SOCKET, SO_BROADCAST, true);
+ if (r < 0)
+ return r;
+ if (address == INADDR_ANY) {
+ /* IP_PKTINFO filter should not be applied when packets are
+ allowed to enter/leave through the interface other than
+ DHCP server sits on(BindToInterface option). */
+ r = setsockopt_int(s, IPPROTO_IP, IP_PKTINFO, true);
+ if (r < 0)
+ return r;
+ }
+ } else {
+ r = setsockopt_int(s, IPPROTO_IP, IP_FREEBIND, true);
+ if (r < 0)
+ return r;
+ }
+
+ if (bind(s, &src.sa, sizeof(src.in)) < 0)
+ return -errno;
+
+ return TAKE_FD(s);
+}
+
+int dhcp_network_send_raw_socket(
+ int s,
+ const union sockaddr_union *link,
+ const void *packet,
+ size_t len) {
+
+ /* Do not add assert(s >= 0) here, as this is called in fuzz-dhcp-server, and in that case this
+ * function should fail with negative errno. */
+
+ assert(link);
+ assert(packet);
+ assert(len > 0);
+
+ if (sendto(s, packet, len, 0, &link->sa, SOCKADDR_LL_LEN(link->ll)) < 0)
+ return -errno;
+
+ return 0;
+}
+
+int dhcp_network_send_udp_socket(
+ int s,
+ be32_t address,
+ uint16_t port,
+ const void *packet,
+ size_t len) {
+
+ union sockaddr_union dest = {
+ .in.sin_family = AF_INET,
+ .in.sin_port = htobe16(port),
+ .in.sin_addr.s_addr = address,
+ };
+
+ assert(s >= 0);
+ assert(packet);
+ assert(len > 0);
+
+ if (sendto(s, packet, len, 0, &dest.sa, sizeof(dest.in)) < 0)
+ return -errno;
+
+ return 0;
+}