udhcpc: don't use BPF filter, users report problems (bugs 4598, 6746)

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 46 insertions, 47 deletions

diff --git a/networking/udhcp/dhcpc.c b/networking/udhcp/dhcpc.c
index 8dee916..ee19f55 100644
--- a/networking/udhcp/dhcpc.c
+++ b/networking/udhcp/dhcpc.c
@@ -976,53 +976,6 @@ static int udhcp_raw_socket(int ifindex)
 	int fd;
 	struct sockaddr_ll sock;
 
-	/*
-	 * 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[] = {
-		/* load 9th byte (protocol) */
-		BPF_STMT(BPF_LD|BPF_B|BPF_ABS, 9),
-		/* jump to L1 if it is IPPROTO_UDP, else to L4 */
-		BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, IPPROTO_UDP, 0, 6),
-		/* L1: load halfword from offset 6 (flags and frag offset) */
-		BPF_STMT(BPF_LD|BPF_H|BPF_ABS, 6),
-		/* jump to L4 if any bits in frag offset field are set, else to L2 */
-		BPF_JUMP(BPF_JMP|BPF_JSET|BPF_K, 0x1fff, 4, 0),
-		/* L2: skip IP header (load index reg with header len) */
-		BPF_STMT(BPF_LDX|BPF_B|BPF_MSH, 0),
-		/* load udp destination port from halfword[header_len + 2] */
-		BPF_STMT(BPF_LD|BPF_H|BPF_IND, 2),
-		/* jump to L3 if udp dport is CLIENT_PORT, else to L4 */
-		BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, 68, 0, 1),
-		/* L3: accept packet */
-		BPF_STMT(BPF_RET|BPF_K, 0xffffffff),
-		/* L4: discard packet */
-		BPF_STMT(BPF_RET|BPF_K, 0),
-	};
-	static const struct sock_fprog filter_prog = {
-		.len = sizeof(filter_instr) / sizeof(filter_instr[0]),
-		/* casting const away: */
-		.filter = (struct sock_filter *) filter_instr,
-	};
-
 	log1("Opening raw socket on ifindex %d", ifindex); //log2?
 
 	fd = xsocket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_IP));
@@ -1033,13 +986,59 @@ static int udhcp_raw_socket(int ifindex)
 	sock.sll_ifindex = ifindex;
 	xbind(fd, (struct sockaddr *) &sock, sizeof(sock));
 
+#if 0 /* Several users reported breakage when BPF filter is used */
 	if (CLIENT_PORT == 68) {
 		/* Use only if standard port is in use */
+		/*
+		 *	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[] = {
+			/* load 9th byte (protocol) */
+			BPF_STMT(BPF_LD|BPF_B|BPF_ABS, 9),
+			/* jump to L1 if it is IPPROTO_UDP, else to L4 */
+			BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, IPPROTO_UDP, 0, 6),
+			/* L1: load halfword from offset 6 (flags and frag offset) */
+			BPF_STMT(BPF_LD|BPF_H|BPF_ABS, 6),
+			/* jump to L4 if any bits in frag offset field are set, else to L2 */
+			BPF_JUMP(BPF_JMP|BPF_JSET|BPF_K, 0x1fff, 4, 0),
+			/* L2: skip IP header (load index reg with header len) */
+			BPF_STMT(BPF_LDX|BPF_B|BPF_MSH, 0),
+			/* load udp destination port from halfword[header_len + 2] */
+			BPF_STMT(BPF_LD|BPF_H|BPF_IND, 2),
+			/* jump to L3 if udp dport is CLIENT_PORT, else to L4 */
+			BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, 68, 0, 1),
+			/* L3: accept packet */
+			BPF_STMT(BPF_RET|BPF_K, 0xffffffff),
+			/* L4: discard packet */
+			BPF_STMT(BPF_RET|BPF_K, 0),
+		};
+		static const struct sock_fprog filter_prog = {
+			.len = sizeof(filter_instr) / sizeof(filter_instr[0]),
+			/* casting const away: */
+			.filter = (struct sock_filter *) filter_instr,
+		};
 		/* Ignoring error (kernel may lack support for this) */
 		if (setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER, &filter_prog,
 				sizeof(filter_prog)) >= 0)
 			log1("Attached filter to raw socket fd"); // log?
 	}
+#endif
 
 	if (setsockopt(fd, SOL_PACKET, PACKET_AUXDATA,
 			&const_int_1, sizeof(int)) < 0