diff options
Diffstat (limited to 'src/libsystemd-network/dhcp-network.c')
| -rw-r--r-- | src/libsystemd-network/dhcp-network.c | 244 |
1 files changed, 244 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..656482b --- /dev/null +++ b/src/libsystemd-network/dhcp-network.c @@ -0,0 +1,244 @@ +/* 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 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, 12), /* A (the MAC address length) == ETH_ALEN ? */ + BPF_STMT(BPF_LD + BPF_IMM, unaligned_read_be32(ð_mac->ether_addr_octet[0])), /* A <- 4 bytes of client's MAC */ + BPF_STMT(BPF_MISC + BPF_TAX, 0), /* X <- A */ + BPF_STMT(BPF_LD + BPF_W + BPF_ABS, offsetof(DHCPPacket, dhcp.chaddr)), /* A <- 4 bytes of MAC from dhcp.chaddr */ + BPF_STMT(BPF_ALU + BPF_XOR + BPF_X, 0), /* A xor X */ + 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_IMM, unaligned_read_be16(ð_mac->ether_addr_octet[4])), /* A <- remainder of client's MAC */ + BPF_STMT(BPF_MISC + BPF_TAX, 0), /* X <- A */ + BPF_STMT(BPF_LD + BPF_H + BPF_ABS, offsetof(DHCPPacket, dhcp.chaddr) + 4), /* A <- remainder of MAC from dhcp.chaddr */ + BPF_STMT(BPF_ALU + BPF_XOR + BPF_X, 0), /* A xor X */ + 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_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, 65535), /* return all */ + }; + 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 (address == INADDR_ANY) { + r = setsockopt_int(s, IPPROTO_IP, IP_PKTINFO, true); + if (r < 0) + return r; + + r = setsockopt_int(s, SOL_SOCKET, SO_BROADCAST, true); + if (r < 0) + return r; + + } else { + r = setsockopt_int(s, IPPROTO_IP, IP_FREEBIND, true); + if (r < 0) + return r; + } + + r = bind(s, &src.sa, sizeof(src.in)); + if (r < 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) { + int r; + + assert(link); + assert(packet); + assert(len); + + r = sendto(s, packet, len, 0, &link->sa, SOCKADDR_LL_LEN(link->ll)); + if (r < 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, + }; + int r; + + assert(s >= 0); + assert(packet); + assert(len); + + r = sendto(s, packet, len, 0, &dest.sa, sizeof(dest.in)); + if (r < 0) + return -errno; + + return 0; +} |