ipv4: add LINUX_MIB_IPRPFILTER snmp counter
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>
diff --git a/include/linux/snmp.h b/include/linux/snmp.h
index 5279771..ebb0c80 100644
--- a/include/linux/snmp.h
+++ b/include/linux/snmp.h
@@ -229,6 +229,7 @@
LINUX_MIB_TCPBACKLOGDROP,
LINUX_MIB_TCPMINTTLDROP, /* RFC 5082 */
LINUX_MIB_TCPDEFERACCEPTDROP,
+ LINUX_MIB_IPRPFILTER, /* IP Reverse Path Filter (rp_filter) */
__LINUX_MIB_MAX
};
diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c
index 4f0ed45..e830f7a 100644
--- a/net/ipv4/fib_frontend.c
+++ b/net/ipv4/fib_frontend.c
@@ -284,7 +284,7 @@
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 @@
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 @@
fib_res_put(&res);
e_inval:
return -EINVAL;
+e_rpf:
+ return -EXDEV;
}
static inline __be32 sk_extract_addr(struct sockaddr *addr)
diff --git a/net/ipv4/ip_input.c b/net/ipv4/ip_input.c
index d930dc5..d52c9da 100644
--- a/net/ipv4/ip_input.c
+++ b/net/ipv4/ip_input.c
@@ -340,6 +340,9 @@
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;
}
}
diff --git a/net/ipv4/proc.c b/net/ipv4/proc.c
index 3dc9914..e320ca6 100644
--- a/net/ipv4/proc.c
+++ b/net/ipv4/proc.c
@@ -252,6 +252,7 @@
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
};
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 8495bce..d377b45 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -1851,6 +1851,7 @@
__be32 spec_dst;
struct in_device *in_dev = in_dev_get(dev);
u32 itag = 0;
+ int err;
/* Primary sanity checks. */
@@ -1865,10 +1866,12 @@
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 @@
return -ENOBUFS;
e_inval:
+ err = -EINVAL;
+e_err:
in_dev_put(in_dev);
- return -EINVAL;
+ return err;
}
@@ -1985,7 +1990,6 @@
ip_handle_martian_source(in_dev->dev, in_dev, skb, daddr,
saddr);
- err = -EINVAL;
goto cleanup;
}
@@ -2157,13 +2161,12 @@
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 @@
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 @@
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,