[1.] One line summary of the problem:
Advanced Source Routing using "ip rule add from <x.x.x.x> lookup <table>" returns error.
[2.] Full description of the problem/report:
I am trying to do advanced source routing. My setup is as follows
tunnel-client tunnel-server
()==============================()
eth0 10.3.30.115/16 10.3.30.93
eth1 192.168.0.10/24
relay 221.221.1.1/32
"relay" is virtual ppp interface, which encapsulates packets into tunnel
connecting the tunnel-server at 10.3.30.93. Both boxes are on 10.3/16 LAN.
I have a kernel module (code below) which does route lookup using
ip_route_output(dst, src, 0, 0).
I have an "ip rule" to send all packets with src ip address 10.81.15.108 to
lookup into table "rlm". Table "rlm" has only a default route towards "relay"
device.
When I do ip_route_output(dst, 0, 0, 0) it succeeds returning next hop as the
default gw. If I do the lookup specifying the src ip address, the route lookup
fails.
I am not able to figure out why the route lookup should fail when src ip address
is specified as a parameter. It should give me the outgoing device as "relay".
Or even if the "ip rule" has not taken effect, it should atleast return the
default route from main table.
Output of the test code and system setup is in section 7.7
Please see the workaround in last section, although its not a feasible solution.
Any help in greatly appreciated.
Best Regards,
Santosh
[3.] Keywords (i.e., modules, networking, kernel):
kernel module
kernel 2.4.26 on Redhat 9.0
advanced routing based on source ip address
ip_route_output()
[4.] Kernel version (from /proc/version):
Linux version 2.4.26 (root@buddy) (gcc version 3.2.2 20030222 (Red Hat Linux 3.2.2-5)) #2 Wed Jul 20 18:09:53 PDT 2005
[6.] A small shell script or example program which triggers the
problem (if possible)
<code>
#ifndef __KERNEL__
# define __KERNEL__
#endif
/* The Makefile takes care of adding -DMODULE */
#include <linux/module.h>
#include <linux/kernel.h> /* printk() */
#include <linux/slab.h> /* kmalloc() */
#include <linux/errno.h> /* error codes */
#include <linux/netdevice.h> /* basic data structures */
#include <linux/init.h> /* __init */
#include <linux/skbuff.h>
#include <linux/if_arp.h> /* ARPHRD_ETHER */
#include <linux/if.h> /* ip header */
#include <linux/in.h>
#include <linux/inet.h>
#include <net/arp.h> /* neighbor stuff */
#include <net/ip.h>
#include <linux/ip.h>
#include <linux/udp.h>
#include <linux/netfilter_ipv4.h>
#include <net/icmp.h>
#include <asm/uaccess.h> /* memcpy and such */
MODULE_AUTHOR("Santosh Gupta.");
MODULE_LICENSE("GPL");
int my_route_lookup (unsigned int dst, unsigned int src)
{
struct rtable *rt;
int rval;
rval = ip_route_output(&rt, dst, src, 0, 0);
if (rval < 0)
{
printk (KERN_EMERG "inquiry for dst:0x%08x src:0x%08x failed", ntohl(dst), ntohl(src));
}
else
{
printk (KERN_EMERG "inquiry for dst:0x%08x src:0x%08x succeeded nh : 0x%08x ifnum %d\n",
ntohl(dst), ntohl(src), ntohl(rt->rt_gateway), rt->u.dst.dev->ifindex);
}
return rval;
}
int init_module(void)
{
unsigned int dst, src;
dst = in_aton("66.94.230.32");
src = in_aton("10.81.15.108");
my_route_lookup (dst, src);
my_route_lookup (dst, 0);
return 0;
}
void cleanup_module(void)
{
}
</code>
To compile, copy the code above to myrelay.c
# gcc -Wall -O -g -DINSANE_DEBUG -I/usr/src/linux/include -DMODULE -o myrelay.o -c myrelay.c
[7.] Environment
[7.1.] Software (add the output of the ver_linux script here)
[dev/9.0/V3_1-RH@macho(115) sgupta]$ sh ver_linux
If some fields are empty or look unusual you may have an old version.
Compare to the current minimal requirements in Documentation/Changes.
Linux macho 2.4.26 #2 Wed Jul 20 18:09:53 PDT 2005 i686 i686 i386 GNU/Linux
Gnu C 3.2.2
Gnu make 3.79.1
util-linux 2.11y
mount 2.11y
modutils 2.4.22
e2fsprogs 1.32
jfsutils 1.0.17
reiserfsprogs 3.6.4
pcmcia-cs 3.1.31
quota-tools 3.06.
isdn4k-utils 3.1pre4
Linux C Library 2.3.2
Dynamic linker (ldd) 2.3.2
Procps 2.0.11
Net-tools 1.60
Kbd 1.08
Sh-utils 4.5.3
Modules Loaded myrelay pppot relay nfs nfsd lockd sunrpc autofs e100 microcode keybdev mousedev input hid usb-uhci ehci-hcd usbcore ext3 jbd
[7.2.] Processor information (from /proc/cpuinfo):
[dev/9.0/V3_1-RH@macho(115) sgupta]$ cat /proc/cpuinfo
processor : 0
vendor_id : GenuineIntel
cpu family : 15
model : 2
model name : Intel(R) Pentium(R) 4 CPU 2.00GHz
stepping : 9
cpu MHz : 1993.555
cache size : 512 KB
fdiv_bug : no
hlt_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 2
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe cid
bogomips : 3971.48
[7.3.] Module information (from /proc/modules):
[dev/9.0/V3_1-RH@macho(115) sgupta]$ cat /proc/modules
myrelay 1096 0 (unused) <--- test code kernel module
pppot 5696 0 (unused) <--- my module
relay 9948 1 <--- relay device
nfs 81304 1 (autoclean)
nfsd 80336 8 (autoclean)
lockd 60016 1 (autoclean) [nfs nfsd]
sunrpc 85084 1 (autoclean) [nfs nfsd lockd]
autofs 13460 1 (autoclean)
e100 56964 2
microcode 5892 0 (autoclean)
keybdev 3136 0 (unused)
mousedev 5556 0 (unused)
input 5760 0 [keybdev mousedev]
hid 19556 0 (unused)
usb-uhci 26348 0 (unused)
ehci-hcd 21160 0 (unused)
usbcore 79008 1 [hid usb-uhci ehci-hcd]
ext3 71588 2
jbd 52212 2 [ext3]
[7.7.] Other information that might be relevant to the problem
(please look in /proc and include all information that you
think to be relevant):
[dev/9.0/V3_1-RH@macho(115) ipv4]# pwd
/proc/sys/net/ipv4
[dev/9.0/V3_1-RH@macho(115) ipv4]# cat ip_forward
1
[dev/9.0/V3_1-RH@macho(115) ipv4]# cd conf/
[dev/9.0/V3_1-RH@macho(115) conf]# cat `find . -name rp_filter`
0
0
0
0
0
0
[dev/9.0/V3_1-RH@macho(115) conf]# cat `find . -name arp_filter`
0
0
0
0
0
0
[dev/9.0/V3_1-RH@macho(115) ipv4]# ip rule list
0: from all lookup local
32764: from 10.81.15.108 lookup rlm
32765: from all fwmark 0x3 lookup rlm
32766: from all lookup main
32767: from all lookup 253
[dev/9.0/V3_1-RH@macho(115) ipv4]# route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
192.168.0.0 0.0.0.0 255.255.255.0 U 0 0 0 eth1
10.3.0.0 0.0.0.0 255.255.0.0 U 0 0 0 eth0
169.254.0.0 0.0.0.0 255.255.0.0 U 0 0 0 eth1
127.0.0.0 0.0.0.0 255.0.0.0 U 0 0 0 lo
0.0.0.0 10.3.1.3 0.0.0.0 UG 0 0 0 eth0
[dev/9.0/V3_1-RH@macho(115) ipv4]# ip route show table rlm
default dev relay scope link
[dev/9.0/V3_1-RH@macho(115) ipv4]# ifconfig -a
eth0 Link encap:Ethernet HWaddr 00:0B:AB:07:CE:23
inet addr:10.3.30.115 Bcast:10.3.255.255 Mask:255.255.0.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:333228 errors:32 dropped:0 overruns:0 frame:32
TX packets:207739 errors:0 dropped:0 overruns:0 carrier:0
collisions:3968 txqueuelen:1000
RX bytes:42179686 (40.2 Mb) TX bytes:39108537 (37.2 Mb)
Interrupt:11 Base address:0xc000 Memory:fc020000-fc020038
eth0:1 Link encap:Ethernet HWaddr 00:0B:AB:07:CE:23
inet addr:172.16.0.20 Bcast:172.16.255.255 Mask:255.255.255.255
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)
Interrupt:11 Base address:0xc000 Memory:fc020000-fc020038
eth0:18 Link encap:Ethernet HWaddr 00:0B:AB:07:CE:23
inet addr:10.3.30.115 Bcast:255.255.255.255 Mask:0.0.0.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)
Interrupt:11 Base address:0xc000 Memory:fc020000-fc020038
eth1 Link encap:Ethernet HWaddr 00:0B:AB:07:CE:22
inet addr:192.168.0.10 Bcast:192.168.0.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:50 errors:0 dropped:0 overruns:0 frame:0
TX packets:59 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:8336 (8.1 Kb) TX bytes:7357 (7.1 Kb)
Interrupt:10 Base address:0xc400 Memory:fc021000-fc021038
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:26658 errors:0 dropped:0 overruns:0 frame:0
TX packets:26658 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:1561321 (1.4 Mb) TX bytes:1561321 (1.4 Mb)
pppot Link encap:Point-to-Point Protocol
POINTOPOINT NOARP MULTICAST MTU:1472 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:100
RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)
relay Link encap:Point-to-Point Protocol
inet addr:221.221.1.1 P-t-P:221.221.1.1 Mask:255.255.255.255
UP POINTOPOINT RUNNING NOARP MULTICAST MTU:1464 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:10
RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)
eth0:1 and eth0:18 are required for some redundancy purposes.
<output>
Message from syslogd@macho at Wed Nov 2 22:06:56 2005 ...
macho kernel: inquiry for dst:0x425ee620 src:0x0a510f6c failed<0>inquiry for dst:0x425ee620 src:0x00000000 succeeded nh : 0x0a030103 ifnum 2
</output>
[X.] Other notes, patches, fixes, workarounds:
If I add an ip rule to do destination based routing, the ip_route_output() gives
correct output when no src ip address is specified as parameter. If src ip
address is specified, it still returns an error.
[dev/9.0/V3_1-RH@macho(115) relay]# ip rule add to 66.94.230.32 lookup rlm
[dev/9.0/V3_1-RH@macho(115) relay]# ip route flush cache
[dev/9.0/V3_1-RH@macho(115) relay]# ip rule list
0: from all lookup local
32763: from all to 66.94.230.32 lookup rlm
32764: from 10.81.15.108 lookup rlm
32765: from all fwmark 0x3 lookup rlm
32766: from all lookup main
32767: from all lookup 253
Note the ifnum is 7 in this case when no src ip address is specified.
<output>
Message from syslogd@macho at Wed Nov 2 22:08:05 2005 ...
macho kernel: inquiry for dst:0x425ee620 src:0x0a510f6c failed<0>inquiry for dst:0x425ee620 src:0x00000000 succeeded nh : 0x425ee620 ifnum 7
</output>
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