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/* 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;
}
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