diff options
| -rw-r--r-- | src/libsystemd-network/dhcp-network.c | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/src/libsystemd-network/dhcp-network.c b/src/libsystemd-network/dhcp-network.c index ecc94b9be7..8bfb2d50af 100644 --- a/src/libsystemd-network/dhcp-network.c +++ b/src/libsystemd-network/dhcp-network.c @@ -25,6 +25,7 @@ #include <net/ethernet.h> #include <stdio.h> #include <unistd.h> +#include <linux/filter.h> #include "socket-util.h" @@ -32,6 +33,19 @@ int dhcp_network_bind_raw_socket(int index, union sockaddr_union *link) { + struct sock_filter filter[] = { + 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_H + BPF_ABS, offsetof(DHCPPacket, udp.dest)), /* A <- UDP destination port */ + BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, DHCP_PORT_CLIENT, 1, 0), /* UDP destination port = DHCP client? */ + 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 + }; int s, one = 1; assert(index > 0); @@ -50,6 +64,10 @@ int dhcp_network_bind_raw_socket(int index, union sockaddr_union *link) if (setsockopt (s, SOL_PACKET, PACKET_AUXDATA, &one, sizeof(one)) < 0) return -errno; + if (setsockopt(s, SOL_SOCKET, SO_ATTACH_FILTER, &fprog, sizeof(fprog)) < 0) { + return -errno; + } + if (bind(s, &link->sa, sizeof(link->ll)) < 0) { safe_close(s); return -errno; |