On Thu, 2014-06-19 at 18:59 +0200, Michal Sekletar wrote: > Check that received DHCP packets actually include our MAC address in > chaddr field. BPF interpreter has 32 bit wide registers but MAC address > is 48 bits long so we have to do check in two steps.
And if the MAC address is not 48 bits (Infiniband) or the interface type doesn't really have a MAC address (PPP/PPPoE)? DHCP can be used in both cases... If anything, the code that uses the MAC address should be if-ed so it only executes when a MAC address is provided. Dan > --- > src/libsystemd-network/dhcp-internal.h | 3 ++- > src/libsystemd-network/dhcp-network.c | 15 +++++++++++++-- > src/libsystemd-network/sd-dhcp-client.c | 4 ++-- > src/libsystemd-network/test-dhcp-client.c | 2 +- > 4 files changed, 18 insertions(+), 6 deletions(-) > > diff --git a/src/libsystemd-network/dhcp-internal.h > b/src/libsystemd-network/dhcp-internal.h > index 03cc824..fd86a70 100644 > --- a/src/libsystemd-network/dhcp-internal.h > +++ b/src/libsystemd-network/dhcp-internal.h > @@ -24,12 +24,13 @@ > > #include <stdint.h> > #include <linux/if_packet.h> > +#include <net/ethernet.h> > > #include "socket-util.h" > > #include "dhcp-protocol.h" > > -int dhcp_network_bind_raw_socket(int index, union sockaddr_union *link, > uint32_t xid); > +int dhcp_network_bind_raw_socket(int index, union sockaddr_union *link, > uint32_t xid, struct ether_addr mac_addr); > int dhcp_network_bind_udp_socket(be32_t address, uint16_t port); > int dhcp_network_send_raw_socket(int s, const union sockaddr_union *link, > const void *packet, size_t len); > diff --git a/src/libsystemd-network/dhcp-network.c > b/src/libsystemd-network/dhcp-network.c > index d7ba0ef..e5fd6a8 100644 > --- a/src/libsystemd-network/dhcp-network.c > +++ b/src/libsystemd-network/dhcp-network.c > @@ -33,7 +33,7 @@ > #include "dhcp-internal.h" > > int dhcp_network_bind_raw_socket(int index, union sockaddr_union *link, > - uint32_t xid) { > + uint32_t xid, struct ether_addr mac_addr) { > 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 ? */ > @@ -56,7 +56,18 @@ int dhcp_network_bind_raw_socket(int index, union > sockaddr_union *link, > 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 */ > - /* TODO: match chaddr */ > + BPF_STMT(BPF_LD + BPF_IMM, htobe32(*((unsigned int *) > &mac_addr))), /* 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, htobe16(*((unsigned short *) (((char > *) &mac_addr) + 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 */ > diff --git a/src/libsystemd-network/sd-dhcp-client.c > b/src/libsystemd-network/sd-dhcp-client.c > index c1af6df..d44cad2 100644 > --- a/src/libsystemd-network/sd-dhcp-client.c > +++ b/src/libsystemd-network/sd-dhcp-client.c > @@ -719,7 +719,7 @@ static int client_start(sd_dhcp_client *client) { > > client->xid = random_u32(); > > - r = dhcp_network_bind_raw_socket(client->index, &client->link, > client->xid); > + r = dhcp_network_bind_raw_socket(client->index, &client->link, > client->xid, client->client_id.mac_addr); > if (r < 0) { > client_stop(client, r); > return r; > @@ -761,7 +761,7 @@ static int client_timeout_t2(sd_event_source *s, uint64_t > usec, void *userdata) > client->state = DHCP_STATE_REBINDING; > client->attempt = 1; > > - r = dhcp_network_bind_raw_socket(client->index, &client->link, > client->xid); > + r = dhcp_network_bind_raw_socket(client->index, &client->link, > client->xid, client->client_id.mac_addr); > if (r < 0) { > client_stop(client, r); > return 0; > diff --git a/src/libsystemd-network/test-dhcp-client.c > b/src/libsystemd-network/test-dhcp-client.c > index 450b6d4..7cbe10d 100644 > --- a/src/libsystemd-network/test-dhcp-client.c > +++ b/src/libsystemd-network/test-dhcp-client.c > @@ -196,7 +196,7 @@ int dhcp_network_send_raw_socket(int s, const union > sockaddr_union *link, > return 575; > } > > -int dhcp_network_bind_raw_socket(int index, union sockaddr_union *link, > uint32_t id) > +int dhcp_network_bind_raw_socket(int index, union sockaddr_union *link, > uint32_t id, struct ether_addr mac) > { > if (socketpair(AF_UNIX, SOCK_STREAM, 0, test_fd) < 0) > return -errno; _______________________________________________ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel