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ipv4: add LINUX_MIB_IPRPFILTER snmp counter

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Christoph Lameter mentioned that packets could be dropped in input path
because of rp_filter settings, without any SNMP counter being
incremented. System administrator can have a hard time to track the
problem.

This patch introduces a new counter, LINUX_MIB_IPRPFILTER, incremented
each time we drop a packet because Reverse Path Filter triggers.

(We receive an IPv4 datagram on a given interface, and find the route to
send an answer would use another interface)

netstat -s | grep IPReversePathFilter
    IPReversePathFilter: 21714

Reported-by: Christoph Lameter <cl@linux-foundation.org>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2010-06-02 12:05:27 +00:00 committed by David S. Miller
parent 8cbccbe761
commit b5f7e75547
5 changed files with 27 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
include/linux/snmp.h
View File

@ -229,6 +229,7 @@ enum
LINUX_MIB_TCPBACKLOGDROP,
LINUX_MIB_TCPMINTTLDROP, /* RFC 5082 */
LINUX_MIB_TCPDEFERACCEPTDROP,
LINUX_MIB_IPRPFILTER, /* IP Reverse Path Filter (rp_filter) */
__LINUX_MIB_MAX
};

6
net/ipv4/fib_frontend.c
View File

@ -284,7 +284,7 @@ int fib_validate_source(__be32 src, __be32 dst, u8 tos, int oif,
if (no_addr)
goto last_resort;
if (rpf == 1)
goto e_inval;
goto e_rpf;
fl.oif = dev->ifindex;
ret = 0;
@ -299,7 +299,7 @@ int fib_validate_source(__be32 src, __be32 dst, u8 tos, int oif,
last_resort:
if (rpf)
goto e_inval;
goto e_rpf;
*spec_dst = inet_select_addr(dev, 0, RT_SCOPE_UNIVERSE);
*itag = 0;
return 0;
@ -308,6 +308,8 @@ e_inval_res:
fib_res_put(&res);
e_inval:
return -EINVAL;
e_rpf:
return -EXDEV;
}
static inline __be32 sk_extract_addr(struct sockaddr *addr)

3
net/ipv4/ip_input.c
View File

@ -340,6 +340,9 @@ static int ip_rcv_finish(struct sk_buff *skb)
else if (err == -ENETUNREACH)
IP_INC_STATS_BH(dev_net(skb->dev),
IPSTATS_MIB_INNOROUTES);
else if (err == -EXDEV)
NET_INC_STATS_BH(dev_net(skb->dev),
LINUX_MIB_IPRPFILTER);
goto drop;
}
}

1
net/ipv4/proc.c
View File

@ -252,6 +252,7 @@ static const struct snmp_mib snmp4_net_list[] = {
SNMP_MIB_ITEM("TCPBacklogDrop", LINUX_MIB_TCPBACKLOGDROP),
SNMP_MIB_ITEM("TCPMinTTLDrop", LINUX_MIB_TCPMINTTLDROP),
SNMP_MIB_ITEM("TCPDeferAcceptDrop", LINUX_MIB_TCPDEFERACCEPTDROP),
SNMP_MIB_ITEM("IPReversePathFilter", LINUX_MIB_IPRPFILTER),
SNMP_MIB_SENTINEL
};

31
net/ipv4/route.c
View File

@ -1851,6 +1851,7 @@ static int ip_route_input_mc(struct sk_buff *skb, __be32 daddr, __be32 saddr,
__be32 spec_dst;
struct in_device *in_dev = in_dev_get(dev);
u32 itag = 0;
int err;
/* Primary sanity checks. */
@ -1865,10 +1866,12 @@ static int ip_route_input_mc(struct sk_buff *skb, __be32 daddr, __be32 saddr,
if (!ipv4_is_local_multicast(daddr))
goto e_inval;
spec_dst = inet_select_addr(dev, 0, RT_SCOPE_LINK);
} else if (fib_validate_source(saddr, 0, tos, 0,
dev, &spec_dst, &itag, 0) < 0)
goto e_inval;
} else {
err = fib_validate_source(saddr, 0, tos, 0, dev, &spec_dst,
&itag, 0);
if (err < 0)
goto e_err;
}
rth = dst_alloc(&ipv4_dst_ops);
if (!rth)
goto e_nobufs;
@ -1920,8 +1923,10 @@ e_nobufs:
return -ENOBUFS;
e_inval:
err = -EINVAL;
e_err:
in_dev_put(in_dev);
return -EINVAL;
return err;
}
@ -1985,7 +1990,6 @@ static int __mkroute_input(struct sk_buff *skb,
ip_handle_martian_source(in_dev->dev, in_dev, skb, daddr,
saddr);
err = -EINVAL;
goto cleanup;
}
@ -2157,13 +2161,12 @@ static int ip_route_input_slow(struct sk_buff *skb, __be32 daddr, __be32 saddr,
goto brd_input;
if (res.type == RTN_LOCAL) {
int result;
result = fib_validate_source(saddr, daddr, tos,
err = fib_validate_source(saddr, daddr, tos,
net->loopback_dev->ifindex,
dev, &spec_dst, &itag, skb->mark);
if (result < 0)
goto martian_source;
if (result)
if (err < 0)
goto martian_source_keep_err;
if (err)
flags |= RTCF_DIRECTSRC;
spec_dst = daddr;
goto local_input;
@ -2191,7 +2194,7 @@ brd_input:
err = fib_validate_source(saddr, 0, tos, 0, dev, &spec_dst,
&itag, skb->mark);
if (err < 0)
goto martian_source;
goto martian_source_keep_err;
if (err)
flags |= RTCF_DIRECTSRC;
}
@ -2272,8 +2275,10 @@ e_nobufs:
goto done;
martian_source:
err = -EINVAL;
martian_source_keep_err:
ip_handle_martian_source(dev, in_dev, skb, daddr, saddr);
goto e_inval;
goto done;
}
int ip_route_input_common(struct sk_buff *skb, __be32 daddr, __be32 saddr,