/* SPDX-License-Identifier: LGPL-2.1-or-later */ /*** Copyright © 2013 Intel Corporation. All rights reserved. ***/ #include #include #include #include #include #include #include #include #include #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 uint8_t *bcast_addr, size_t bcast_addr_len, const struct ether_addr *eth_mac, uint16_t arp_type, uint8_t dhcp_hlen, uint16_t port) { 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, dhcp_hlen, 1, 0), /* address length == dhcp_hlen ? */ 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(ð_mac->ether_addr_octet[0])), /* 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(ð_mac->ether_addr_octet[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; assert(ifindex > 0); assert(link); 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_len, }; memcpy(link->ll.sll_addr, bcast_addr, bcast_addr_len); /* We may overflow link->ll. link->ll_buffer ensures we have enough space. */ 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 uint8_t *mac_addr, size_t mac_addr_len, const uint8_t *bcast_addr, size_t bcast_addr_len, uint16_t arp_type, uint16_t port) { static const uint8_t eth_bcast[] = { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF }; /* Default broadcast address for IPoIB */ static const uint8_t ib_bcast[] = { 0x00, 0xff, 0xff, 0xff, 0xff, 0x12, 0x40, 0x1b, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xff, 0xff, 0xff, 0xff }; struct ether_addr eth_mac = { { 0, 0, 0, 0, 0, 0 } }; const uint8_t *default_bcast_addr; size_t expected_bcast_addr_len; uint8_t dhcp_hlen = 0; if (arp_type == ARPHRD_ETHER) { assert_return(mac_addr_len == ETH_ALEN, -EINVAL); memcpy(ð_mac, mac_addr, ETH_ALEN); dhcp_hlen = ETH_ALEN; default_bcast_addr = eth_bcast; expected_bcast_addr_len = ETH_ALEN; } else if (arp_type == ARPHRD_INFINIBAND) { default_bcast_addr = ib_bcast; expected_bcast_addr_len = INFINIBAND_ALEN; } else return -EINVAL; if (bcast_addr && bcast_addr_len > 0) assert_return(bcast_addr_len == expected_bcast_addr_len, -EINVAL); else { bcast_addr = default_bcast_addr; bcast_addr_len = expected_bcast_addr_len; } return _bind_raw_socket(ifindex, link, xid, bcast_addr, bcast_addr_len, ð_mac, arp_type, dhcp_hlen, port); } 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; }