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

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

diff --git a/networking/udhcp/dhcpc.c b/networking/udhcp/dhcpc.c
index 8dee916d9892cdb6d2eb249916109a8ccff9478c..ee19f55780cbec654901890159ba27db38fdb218 100644 (file)
--- 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