diff options
| -rw-r--r-- | networking/udhcp/clientsocket.c | 55 | ||||
| -rw-r--r-- | networking/udhcp/common.h | 7 | ||||
| -rw-r--r-- | networking/udhcp/dhcpc.c | 3 | ||||
| -rw-r--r-- | networking/udhcp/dhcprelay.c | 6 | ||||
| -rw-r--r-- | networking/udhcp/options.h | 3 |
5 files changed, 64 insertions, 10 deletions
diff --git a/networking/udhcp/clientsocket.c b/networking/udhcp/clientsocket.c index 541f883b5..954db5319 100644 --- a/networking/udhcp/clientsocket.c +++ b/networking/udhcp/clientsocket.c @@ -30,22 +30,75 @@ #include <linux/if_packet.h> #include <linux/if_ether.h> #endif +#include <linux/filter.h> #include "common.h" +#define SERVER_AND_CLIENT_PORTS ((SERVER_PORT << 16) + CLIENT_PORT) int raw_socket(int ifindex) { int fd; struct sockaddr_ll sock; - DEBUG("Opening raw socket on ifindex %d", ifindex); + /* + * Comment: + * + * I've selected not to see LL header, so BPF doesn't see it, too. + * The filter may also pass non-IP and non-ARP packets, but we do + * a more complete check when receiving the message in userspace. + * + * and filter shamelessly stolen from: + * + * http://www.flamewarmaster.de/software/dhcpclient/ + * + * There are a few other interesting ideas on that page (look under + * "Motivation"). Use of netlink events is most interesting. Think + * of various network servers listening for events and reconfiguring. + * That would obsolete sending HUP signals and/or make use of restarts. + * + * Copyright: 2006, 2007 Stefan Rompf <sux@loplof.de>. + * License: GPL v2. + * + * TODO: make conditional? + */ + static const struct sock_filter filter_instr[] = { + /* check for udp */ + BPF_STMT(BPF_LD|BPF_B|BPF_ABS, 9), + BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, IPPROTO_UDP, 2, 0), /* L5, L1, is UDP? */ + /* ugly check for arp on ethernet-like and IPv4 */ + BPF_STMT(BPF_LD|BPF_W|BPF_ABS, 2), /* L1: */ + BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, 0x08000604, 3, 4), /* L3, L4 */ + /* skip IP header */ + BPF_STMT(BPF_LDX|BPF_B|BPF_MSH, 0), /* L5: */ + /* check udp source and destination ports */ + BPF_STMT(BPF_LD|BPF_W|BPF_IND, 0), + BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, SERVER_AND_CLIENT_PORTS, 0, 1), /* L3, L4 */ + /* returns */ + BPF_STMT(BPF_RET|BPF_K, ~0UL), /* L3: pass */ + BPF_STMT(BPF_RET|BPF_K, 0), /* L4: reject */ + }; + static const struct sock_fprog filter_prog = { + .len = sizeof(filter_instr) / sizeof(filter_instr[0]), + /* casting const away: */ + .filter = (struct sock_filter *) filter_instr, + }; + + DEBUG("opening raw socket on ifindex %d", ifindex); + fd = xsocket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_IP)); + DEBUG("got raw socket fd %d", fd); + + /* Ignoring error (kernel may lack support for this) */ + if (setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER, &filter_prog, + sizeof(filter_prog)) >= 0) + DEBUG("attached filter to raw socket fd %d", fd); sock.sll_family = AF_PACKET; sock.sll_protocol = htons(ETH_P_IP); sock.sll_ifindex = ifindex; xbind(fd, (struct sockaddr *) &sock, sizeof(sock)); + DEBUG("bound to raw socket fd %d", fd); return fd; } diff --git a/networking/udhcp/common.h b/networking/udhcp/common.h index 38ede0124..b1d629b18 100644 --- a/networking/udhcp/common.h +++ b/networking/udhcp/common.h @@ -14,6 +14,9 @@ #define DEFAULT_SCRIPT "/usr/share/udhcpc/default.script" +#define SERVER_PORT 67 +#define CLIENT_PORT 68 + extern const uint8_t MAC_BCAST_ADDR[6]; /* six all-ones */ /*** packet.h ***/ @@ -21,7 +24,7 @@ extern const uint8_t MAC_BCAST_ADDR[6]; /* six all-ones */ #include <netinet/udp.h> #include <netinet/ip.h> -#define DHCP_OPTIONS_BUFSIZE 308 +#define DHCP_OPTIONS_BUFSIZE 308 struct dhcpMessage { uint8_t op; @@ -93,7 +96,7 @@ int listen_socket(/*uint32_t ip,*/ int port, const char *inf); int arpping(uint32_t test_ip, uint32_t from_ip, uint8_t *from_mac, const char *interface); #if ENABLE_FEATURE_UDHCP_DEBUG -# define DEBUG(str, args...) bb_info_msg(str, ## args) +# define DEBUG(str, args...) bb_info_msg("### " str, ## args) #else # define DEBUG(str, args...) do {;} while (0) #endif diff --git a/networking/udhcp/dhcpc.c b/networking/udhcp/dhcpc.c index e9b728ab5..f54bc08f1 100644 --- a/networking/udhcp/dhcpc.c +++ b/networking/udhcp/dhcpc.c @@ -452,7 +452,8 @@ int udhcpc_main(int argc, char **argv) if (listen_mode == LISTEN_KERNEL) len = udhcp_recv_packet(&packet, sockfd); - else len = get_raw_packet(&packet, sockfd); + else + len = get_raw_packet(&packet, sockfd); if (len == -1) { /* error is severe, reopen socket */ DEBUG("error on read, %s, reopening socket", strerror(errno)); diff --git a/networking/udhcp/dhcprelay.c b/networking/udhcp/dhcprelay.c index a6483fc1f..c243cc16c 100644 --- a/networking/udhcp/dhcprelay.c +++ b/networking/udhcp/dhcprelay.c @@ -155,12 +155,12 @@ static int init_sockets(char **client, int num_clients, int i, n; /* talk to real server on bootps */ - fds[0] = listen_socket(/*INADDR_ANY,*/ 67, server); + fds[0] = listen_socket(/*INADDR_ANY,*/ SERVER_PORT, server); n = fds[0]; for (i = 1; i < num_clients; i++) { /* listen for clients on bootps */ - fds[i] = listen_socket(/*INADDR_ANY,*/ 67, client[i-1]); + fds[i] = listen_socket(/*INADDR_ANY,*/ SERVER_PORT, client[i-1]); if (fds[i] > n) n = fds[i]; } @@ -289,7 +289,7 @@ int dhcprelay_main(int argc, char **argv) struct sockaddr_in server_addr; server_addr.sin_family = AF_INET; - server_addr.sin_port = htons(67); + server_addr.sin_port = htons(SERVER_PORT); if (argc == 4) { if (!inet_aton(argv[3], &server_addr.sin_addr)) bb_perror_msg_and_die("didn't grok server"); diff --git a/networking/udhcp/options.h b/networking/udhcp/options.h index c98aec48f..e9eeefb57 100644 --- a/networking/udhcp/options.h +++ b/networking/udhcp/options.h @@ -28,9 +28,6 @@ enum { /*****************************************************************/ /* DHCP protocol -- see RFC 2131 */ -#define SERVER_PORT 67 -#define CLIENT_PORT 68 - #define DHCP_MAGIC 0x63825363 |