From b5f7e7554753e2cc3ef3bef0271fdb32027df2ba Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Wed, 2 Jun 2010 12:05:27 +0000 Subject: [PATCH] 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 Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- include/linux/snmp.h | 1 + net/ipv4/fib_frontend.c | 6 ++++-- net/ipv4/ip_input.c | 3 +++ net/ipv4/proc.c | 1 + net/ipv4/route.c | 31 ++++++++++++++++++------------- 5 files changed, 27 insertions(+), 15 deletions(-) diff --git a/include/linux/snmp.h b/include/linux/snmp.h index 52797714ade7..ebb0c80ffd6e 100644 --- a/include/linux/snmp.h +++ b/include/linux/snmp.h @@ -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 }; diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c index 4f0ed458c883..e830f7a123bd 100644 --- a/net/ipv4/fib_frontend.c +++ b/net/ipv4/fib_frontend.c @@ -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) diff --git a/net/ipv4/ip_input.c b/net/ipv4/ip_input.c index d930dc5e4d85..d52c9da644cf 100644 --- a/net/ipv4/ip_input.c +++ b/net/ipv4/ip_input.c @@ -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; } } diff --git a/net/ipv4/proc.c b/net/ipv4/proc.c index 3dc9914c1dce..e320ca6b3ef3 100644 --- a/net/ipv4/proc.c +++ b/net/ipv4/proc.c @@ -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 }; diff --git a/net/ipv4/route.c b/net/ipv4/route.c index 8495bceec764..d377b45005fc 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -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, -- 2.30.2