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Message-Id: <20241007074702.249543-2-dongml2@chinatelecom.cn>
Date: Mon, 7 Oct 2024 15:46:56 +0800
From: Menglong Dong <menglong8.dong@...il.com>
To: edumazet@...gle.com,
kuba@...nel.org
Cc: davem@...emloft.net,
pabeni@...hat.com,
dsahern@...nel.org,
steffen.klassert@...unet.com,
herbert@...dor.apana.org.au,
dongml2@...natelecom.cn,
bigeasy@...utronix.de,
toke@...hat.com,
idosch@...dia.com,
netdev@...r.kernel.org,
linux-kernel@...r.kernel.org,
bpf@...r.kernel.org
Subject: [PATCH net-next v2 1/7] net: ip: make fib_validate_source() return drop reason
In this commit, we make fib_validate_source/__fib_validate_source return
-reason instead of errno on error. As the return value of them can be
-errno, 0, and 1, we can't make it return enum skb_drop_reason directly.
In the origin logic, if __fib_validate_source() return -EXDEV,
LINUX_MIB_IPRPFILTER will be counted. And now, we need to adjust it by
checking "reason == SKB_DROP_REASON_IP_RPFILTER". However, this will take
effect only after the patch "net: ip: make ip_route_input_noref() return
drop reasons", as we can't pass the drop reasons from
fib_validate_source() to ip_rcv_finish_core() in this patch.
We set the errno to -EINVAL when fib_validate_source() is called and the
validation fails, as the errno can be checked in the caller and now its
value is -reason, which can lead misunderstand.
Following new drop reasons are added in this patch:
SKB_DROP_REASON_IP_LOCAL_SOURCE
SKB_DROP_REASON_IP_INVALID_SOURCE
Signed-off-by: Menglong Dong <dongml2@...natelecom.cn>
---
include/net/dropreason-core.h | 10 ++++++++++
net/ipv4/fib_frontend.c | 19 +++++++++++++------
net/ipv4/ip_input.c | 4 +---
net/ipv4/route.c | 15 +++++++++++----
4 files changed, 35 insertions(+), 13 deletions(-)
diff --git a/include/net/dropreason-core.h b/include/net/dropreason-core.h
index 4748680e8c88..76504e25d581 100644
--- a/include/net/dropreason-core.h
+++ b/include/net/dropreason-core.h
@@ -76,6 +76,8 @@
FN(INVALID_PROTO) \
FN(IP_INADDRERRORS) \
FN(IP_INNOROUTES) \
+ FN(IP_LOCAL_SOURCE) \
+ FN(IP_INVALID_SOURCE) \
FN(PKT_TOO_BIG) \
FN(DUP_FRAG) \
FN(FRAG_REASM_TIMEOUT) \
@@ -365,6 +367,14 @@ enum skb_drop_reason {
* IPSTATS_MIB_INADDRERRORS
*/
SKB_DROP_REASON_IP_INNOROUTES,
+ /** @SKB_DROP_REASON_IP_LOCAL_SOURCE: the source ip is local */
+ SKB_DROP_REASON_IP_LOCAL_SOURCE,
+ /**
+ * @SKB_DROP_REASON_IP_INVALID_SOURCE: the source ip is invalid:
+ * 1) source ip is multicast or limited broadcast
+ * 2) source ip is zero and not IGMP
+ */
+ SKB_DROP_REASON_IP_INVALID_SOURCE,
/**
* @SKB_DROP_REASON_PKT_TOO_BIG: packet size is too big (maybe exceed the
* MTU)
diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c
index 793e6781399a..779c90de3a54 100644
--- a/net/ipv4/fib_frontend.c
+++ b/net/ipv4/fib_frontend.c
@@ -346,6 +346,7 @@ static int __fib_validate_source(struct sk_buff *skb, __be32 src, __be32 dst,
int rpf, struct in_device *idev, u32 *itag)
{
struct net *net = dev_net(dev);
+ enum skb_drop_reason reason;
struct flow_keys flkeys;
int ret, no_addr;
struct fib_result res;
@@ -377,9 +378,15 @@ static int __fib_validate_source(struct sk_buff *skb, __be32 src, __be32 dst,
if (fib_lookup(net, &fl4, &res, 0))
goto last_resort;
- if (res.type != RTN_UNICAST &&
- (res.type != RTN_LOCAL || !IN_DEV_ACCEPT_LOCAL(idev)))
- goto e_inval;
+ if (res.type != RTN_UNICAST) {
+ if (res.type != RTN_LOCAL) {
+ reason = SKB_DROP_REASON_IP_INVALID_SOURCE;
+ goto e_inval;
+ } else if (!IN_DEV_ACCEPT_LOCAL(idev)) {
+ reason = SKB_DROP_REASON_IP_LOCAL_SOURCE;
+ goto e_inval;
+ }
+ }
fib_combine_itag(itag, &res);
dev_match = fib_info_nh_uses_dev(res.fi, dev);
@@ -412,9 +419,9 @@ static int __fib_validate_source(struct sk_buff *skb, __be32 src, __be32 dst,
return 0;
e_inval:
- return -EINVAL;
+ return -reason;
e_rpf:
- return -EXDEV;
+ return -SKB_DROP_REASON_IP_RPFILTER;
}
/* Ignore rp_filter for packets protected by IPsec. */
@@ -440,7 +447,7 @@ int fib_validate_source(struct sk_buff *skb, __be32 src, __be32 dst,
* and the same host but different containers are not.
*/
if (inet_lookup_ifaddr_rcu(net, src))
- return -EINVAL;
+ return -SKB_DROP_REASON_IP_LOCAL_SOURCE;
ok:
*itag = 0;
diff --git a/net/ipv4/ip_input.c b/net/ipv4/ip_input.c
index c0a2490eb7c1..a6f5bfc274ee 100644
--- a/net/ipv4/ip_input.c
+++ b/net/ipv4/ip_input.c
@@ -425,10 +425,8 @@ static int ip_rcv_finish_core(struct net *net, struct sock *sk,
return NET_RX_DROP;
drop_error:
- if (err == -EXDEV) {
- drop_reason = SKB_DROP_REASON_IP_RPFILTER;
+ if (drop_reason == SKB_DROP_REASON_IP_RPFILTER)
__NET_INC_STATS(net, LINUX_MIB_IPRPFILTER);
- }
goto drop;
}
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 6e1cd0065b87..e49b4ce1804a 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -1690,7 +1690,7 @@ int ip_mc_validate_source(struct sk_buff *skb, __be32 daddr, __be32 saddr,
err = fib_validate_source(skb, saddr, 0, tos, 0, dev,
in_dev, itag);
if (err < 0)
- return err;
+ return -EINVAL;
}
return 0;
}
@@ -1788,6 +1788,7 @@ static int __mkroute_input(struct sk_buff *skb,
err = fib_validate_source(skb, saddr, daddr, tos, FIB_RES_OIF(*res),
in_dev->dev, in_dev, &itag);
if (err < 0) {
+ err = -EINVAL;
ip_handle_martian_source(in_dev->dev, in_dev, skb, daddr,
saddr);
@@ -2162,8 +2163,10 @@ int ip_route_use_hint(struct sk_buff *skb, __be32 daddr, __be32 saddr,
tos &= INET_DSCP_MASK;
err = fib_validate_source(skb, saddr, daddr, tos, 0, dev, in_dev, &tag);
- if (err < 0)
+ if (err < 0) {
+ err = -EINVAL;
goto martian_source;
+ }
skip_validate_source:
skb_dst_copy(skb, hint);
@@ -2302,8 +2305,10 @@ static int ip_route_input_slow(struct sk_buff *skb, __be32 daddr, __be32 saddr,
err = fib_validate_source(skb, saddr, daddr,
inet_dscp_to_dsfield(dscp), 0, dev,
in_dev, &itag);
- if (err < 0)
+ if (err < 0) {
+ err = -EINVAL;
goto martian_source;
+ }
goto local_input;
}
@@ -2327,8 +2332,10 @@ out: return err;
err = fib_validate_source(skb, saddr, 0,
inet_dscp_to_dsfield(dscp), 0, dev,
in_dev, &itag);
- if (err < 0)
+ if (err < 0) {
+ err = -EINVAL;
goto martian_source;
+ }
}
flags |= RTCF_BROADCAST;
res->type = RTN_BROADCAST;
--
2.39.5
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