+++ /dev/null
-dhcp-client: Ignore partial checksums
-
-dhclient will fail to get an IP address if run inside a guest when traffic is
-flowing over a virtual network interface. The user will see the error
-message:
-
- 5 bad udp checksums in 5 packets
- No DHCPOFFERS received.
- Unable to obtain a lease on first try. Exiting.
- Failed to bring up eth0.
-
-This is because Linux only uses partial checksums for packets that go over
-virtual network interfaces and dhclient does not like this.
-
- See linux kernel commit 78ea85f17b15390e30d8b47488ec7b6cf0790663
- ("net: skbuff: improve comment on checksumming")
-
-An application can detect this behaviour by checking for the
-TP_STATUS_CSUMNOTREADY flag in the tp_status field.
-
- See linux kernel commit 8dc4194474159660d7f37c495e3fc3f10d0db8cc
- ("Add optional checksum computation for recvmsg")
-
-An extra parameter is added to decode_udp_ip_header() in dhclient to indicate
-whether or not dhclient should ignore partial checksums. This is used
-when the TP_STATUS_CSUMNOTREADY bit is set by the guest kernel.
-
-This fix has been included in Fedora and Ubuntu, however it has not yet been
-accepted by ISC upstream. Likely because it is specific to behaviour in Linux
-and other UNIX variants do not seem to be affected.
-
-The patch was imported from the dhcp source RPM in Fedora 21
- (http://pkgs.fedoraproject.org/cgit/dhcp.git/tree/dhcp-xen-checksum.patch?h=f21)
-
-Originally contributed to fedora-cvs-commit by David Cantrell on Jan 30 2007
- (https://www.redhat.com/archives/fedora-cvs-commits/2007-January/msg01442.html)
-
-Submitted to dhcp-bugs@isc.org - [ISC-Bugs #22806] - by Michael S. Tsirkin
- (http://comments.gmane.org/gmane.comp.emulators.kvm.devel/65236)
- (https://lists.isc.org/pipermail/dhcp-hackers/2010-April/001835.html)
-
-Upstream-Status: Submitted [dhcp-bugs@isc.org]
-Signed-off-by: Rob Woolley <rob.woolley@windriver.com>
---
- common/bpf.c | 2 -
- common/dlpi.c | 2 -
- common/lpf.c | 83 +++++++++++++++++++++++++++++++++++++++++--------------
- common/nit.c | 2 -
- common/packet.c | 4 +-
- common/upf.c | 2 -
- includes/dhcpd.h | 2 -
- 7 files changed, 70 insertions(+), 27 deletions(-)
-
-diff --git a/common/bpf.c b/common/bpf.c
---- a/common/bpf.c
-+++ b/common/bpf.c
-@@ -481,7 +481,7 @@ ssize_t receive_packet (interface, buf,
- /* Decode the IP and UDP headers... */
- offset = decode_udp_ip_header(interface, interface->rbuf,
- interface->rbuf_offset,
-- from, hdr.bh_caplen, &paylen);
-+ from, hdr.bh_caplen, &paylen, 0);
-
- /* If the IP or UDP checksum was bad, skip the packet... */
- if (offset < 0) {
-diff --git a/common/dlpi.c b/common/dlpi.c
---- a/common/dlpi.c
-+++ b/common/dlpi.c
-@@ -691,7 +691,7 @@ ssize_t receive_packet (interface, buf,
- length -= offset;
- #endif
- offset = decode_udp_ip_header (interface, dbuf, bufix,
-- from, length, &paylen);
-+ from, length, &paylen, 0);
-
- /*
- * If the IP or UDP checksum was bad, skip the packet...
-diff --git a/common/lpf.c b/common/lpf.c
---- a/common/lpf.c
-+++ b/common/lpf.c
-@@ -29,14 +29,15 @@
-
- #include "dhcpd.h"
- #if defined (USE_LPF_SEND) || defined (USE_LPF_RECEIVE)
-+#include <sys/socket.h>
- #include <sys/uio.h>
- #include <errno.h>
-
- #include <asm/types.h>
- #include <linux/filter.h>
- #include <linux/if_ether.h>
-+#include <linux/if_packet.h>
- #include <netinet/in_systm.h>
--#include <net/if_packet.h>
- #include "includes/netinet/ip.h"
- #include "includes/netinet/udp.h"
- #include "includes/netinet/if_ether.h"
-@@ -51,6 +52,19 @@
- /* Reinitializes the specified interface after an address change. This
- is not required for packet-filter APIs. */
-
-+#ifndef PACKET_AUXDATA
-+#define PACKET_AUXDATA 8
-+
-+struct tpacket_auxdata
-+{
-+ __u32 tp_status;
-+ __u32 tp_len;
-+ __u32 tp_snaplen;
-+ __u16 tp_mac;
-+ __u16 tp_net;
-+};
-+#endif
-+
- #ifdef USE_LPF_SEND
- void if_reinitialize_send (info)
- struct interface_info *info;
-@@ -73,10 +87,14 @@ int if_register_lpf (info)
- struct interface_info *info;
- {
- int sock;
-- struct sockaddr sa;
-+ union {
-+ struct sockaddr_ll ll;
-+ struct sockaddr common;
-+ } sa;
-+ struct ifreq ifr;
-
- /* Make an LPF socket. */
-- if ((sock = socket(PF_PACKET, SOCK_PACKET,
-+ if ((sock = socket(PF_PACKET, SOCK_RAW,
- htons((short)ETH_P_ALL))) < 0) {
- if (errno == ENOPROTOOPT || errno == EPROTONOSUPPORT ||
- errno == ESOCKTNOSUPPORT || errno == EPFNOSUPPORT ||
-@@ -91,11 +109,17 @@ int if_register_lpf (info)
- log_fatal ("Open a socket for LPF: %m");
- }
-
-+ memset (&ifr, 0, sizeof ifr);
-+ strncpy (ifr.ifr_name, (const char *)info -> ifp, sizeof ifr.ifr_name);
-+ ifr.ifr_name[IFNAMSIZ-1] = '\0';
-+ if (ioctl (sock, SIOCGIFINDEX, &ifr))
-+ log_fatal ("Failed to get interface index: %m");
-+
- /* Bind to the interface name */
- memset (&sa, 0, sizeof sa);
-- sa.sa_family = AF_PACKET;
-- strncpy (sa.sa_data, (const char *)info -> ifp, sizeof sa.sa_data);
-- if (bind (sock, &sa, sizeof sa)) {
-+ sa.ll.sll_family = AF_PACKET;
-+ sa.ll.sll_ifindex = ifr.ifr_ifindex;
-+ if (bind (sock, &sa.common, sizeof sa)) {
- if (errno == ENOPROTOOPT || errno == EPROTONOSUPPORT ||
- errno == ESOCKTNOSUPPORT || errno == EPFNOSUPPORT ||
- errno == EAFNOSUPPORT || errno == EINVAL) {
-@@ -177,9 +201,18 @@ static void lpf_gen_filter_setup (struct
- void if_register_receive (info)
- struct interface_info *info;
- {
-+ int val;
-+
- /* Open a LPF device and hang it on this interface... */
- info -> rfdesc = if_register_lpf (info);
-
-+ val = 1;
-+ if (setsockopt (info -> rfdesc, SOL_PACKET, PACKET_AUXDATA, &val,
-+ sizeof val) < 0) {
-+ if (errno != ENOPROTOOPT)
-+ log_fatal ("Failed to set auxiliary packet data: %m");
-+ }
-+
- #if defined (HAVE_TR_SUPPORT)
- if (info -> hw_address.hbuf [0] == HTYPE_IEEE802)
- lpf_tr_filter_setup (info);
-@@ -301,7 +334,6 @@ ssize_t send_packet (interface, packet,
- double hh [16];
- double ih [1536 / sizeof (double)];
- unsigned char *buf = (unsigned char *)ih;
-- struct sockaddr_pkt sa;
- int result;
- int fudge;
-
-@@ -322,17 +354,7 @@ ssize_t send_packet (interface, packet,
- (unsigned char *)raw, len);
- memcpy (buf + ibufp, raw, len);
-
-- /* For some reason, SOCK_PACKET sockets can't be connected,
-- so we have to do a sentdo every time. */
-- memset (&sa, 0, sizeof sa);
-- sa.spkt_family = AF_PACKET;
-- strncpy ((char *)sa.spkt_device,
-- (const char *)interface -> ifp, sizeof sa.spkt_device);
-- sa.spkt_protocol = htons(ETH_P_IP);
--
-- result = sendto (interface -> wfdesc,
-- buf + fudge, ibufp + len - fudge, 0,
-- (const struct sockaddr *)&sa, sizeof sa);
-+ result = write (interface -> wfdesc, buf + fudge, ibufp + len - fudge);
- if (result < 0)
- log_error ("send_packet: %m");
- return result;
-@@ -349,14 +371,35 @@ ssize_t receive_packet (interface, buf,
- {
- int length = 0;
- int offset = 0;
-+ int nocsum = 0;
- unsigned char ibuf [1536];
- unsigned bufix = 0;
- unsigned paylen;
-+ unsigned char cmsgbuf[CMSG_LEN(sizeof(struct tpacket_auxdata))];
-+ struct iovec iov = {
-+ .iov_base = ibuf,
-+ .iov_len = sizeof ibuf,
-+ };
-+ struct msghdr msg = {
-+ .msg_iov = &iov,
-+ .msg_iovlen = 1,
-+ .msg_control = cmsgbuf,
-+ .msg_controllen = sizeof(cmsgbuf),
-+ };
-+ struct cmsghdr *cmsg;
-
-- length = read (interface -> rfdesc, ibuf, sizeof ibuf);
-+ length = recvmsg (interface -> rfdesc, &msg, 0);
- if (length <= 0)
- return length;
-
-+ for (cmsg = CMSG_FIRSTHDR(&msg); cmsg; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
-+ if (cmsg->cmsg_level == SOL_PACKET &&
-+ cmsg->cmsg_type == PACKET_AUXDATA) {
-+ struct tpacket_auxdata *aux = (void *)CMSG_DATA(cmsg);
-+ nocsum = aux->tp_status & TP_STATUS_CSUMNOTREADY;
-+ }
-+ }
-+
- bufix = 0;
- /* Decode the physical header... */
- offset = decode_hw_header (interface, ibuf, bufix, hfrom);
-@@ -373,7 +416,7 @@ ssize_t receive_packet (interface, buf,
-
- /* Decode the IP and UDP headers... */
- offset = decode_udp_ip_header (interface, ibuf, bufix, from,
-- (unsigned)length, &paylen);
-+ (unsigned)length, &paylen, nocsum);
-
- /* If the IP or UDP checksum was bad, skip the packet... */
- if (offset < 0)
-diff --git a/common/nit.c b/common/nit.c
---- a/common/nit.c
-+++ b/common/nit.c
-@@ -363,7 +363,7 @@ ssize_t receive_packet (interface, buf,
-
- /* Decode the IP and UDP headers... */
- offset = decode_udp_ip_header (interface, ibuf, bufix,
-- from, length, &paylen);
-+ from, length, &paylen, 0);
-
- /* If the IP or UDP checksum was bad, skip the packet... */
- if (offset < 0)
-diff --git a/common/packet.c b/common/packet.c
---- a/common/packet.c
-+++ b/common/packet.c
-@@ -226,7 +226,7 @@ ssize_t
- decode_udp_ip_header(struct interface_info *interface,
- unsigned char *buf, unsigned bufix,
- struct sockaddr_in *from, unsigned buflen,
-- unsigned *rbuflen)
-+ unsigned *rbuflen, int nocsum)
- {
- unsigned char *data;
- struct ip ip;
-@@ -337,7 +337,7 @@ decode_udp_ip_header(struct interface_in
- 8, IPPROTO_UDP + ulen))));
-
- udp_packets_seen++;
-- if (usum && usum != sum) {
-+ if (!nocsum && usum && usum != sum) {
- udp_packets_bad_checksum++;
- if (udp_packets_seen > 4 &&
- (udp_packets_seen / udp_packets_bad_checksum) < 2) {
-diff --git a/common/upf.c b/common/upf.c
---- a/common/upf.c
-+++ b/common/upf.c
-@@ -314,7 +314,7 @@ ssize_t receive_packet (interface, buf,
-
- /* Decode the IP and UDP headers... */
- offset = decode_udp_ip_header (interface, ibuf, bufix,
-- from, length, &paylen);
-+ from, length, &paylen, 0);
-
- /* If the IP or UDP checksum was bad, skip the packet... */
- if (offset < 0)
-diff --git a/includes/dhcpd.h b/includes/dhcpd.h
---- a/includes/dhcpd.h
-+++ b/includes/dhcpd.h
-@@ -2857,7 +2857,7 @@ ssize_t decode_hw_header (struct interfa
- unsigned, struct hardware *);
- ssize_t decode_udp_ip_header (struct interface_info *, unsigned char *,
- unsigned, struct sockaddr_in *,
-- unsigned, unsigned *);
-+ unsigned, unsigned *, int);
-
- /* ethernet.c */
- void assemble_ethernet_header (struct interface_info *, unsigned char *,
---
-1.8.1.2
-
