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Message-Id: <20241024093348.353245-2-dongml2@chinatelecom.cn>
Date: Thu, 24 Oct 2024 17:33:40 +0800
From: Menglong Dong <menglong8.dong@...il.com>
To: pabeni@...hat.com
Cc: davem@...emloft.net,
edumazet@...gle.com,
kuba@...nel.org,
dsahern@...nel.org,
pablo@...filter.org,
kadlec@...filter.org,
roopa@...dia.com,
razor@...ckwall.org,
gnault@...hat.com,
bigeasy@...utronix.de,
idosch@...dia.com,
ast@...nel.org,
dongml2@...natelecom.cn,
netdev@...r.kernel.org,
linux-kernel@...r.kernel.org,
netfilter-devel@...r.kernel.org,
coreteam@...filter.org,
bridge@...ts.linux.dev,
bpf@...r.kernel.org
Subject: [PATCH bpf-next v4 1/9] net: ip: make fib_validate_source() support drop reasons
In this commit, we make fib_validate_source() and __fib_validate_source()
return -reason instead of errno on error.
The return value of fib_validate_source can be -errno, 0, and 1. It's hard
to make fib_validate_source() return drop reasons directly.
The fib_validate_source() will return 1 if the scope of the source(revert)
route is HOST. And the __mkroute_input() will mark the skb with
IPSKB_DOREDIRECT in this case (combine with some other conditions). And
then, a REDIRECT ICMP will be sent in ip_forward() if this flag exists. We
can't pass this information to __mkroute_input if we make
fib_validate_source() return drop reasons.
Therefore, we introduce the wrapper fib_validate_source_reason() for
fib_validate_source(), which will return the drop reasons on error.
In the origin logic, LINUX_MIB_IPRPFILTER will be counted if
fib_validate_source() return -EXDEV. 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.
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>
---
v4:
- don't refactor fib_validate_source/__fib_validate_source, and introduce
a wrapper for fib_validate_source() instead.
v2:
- make fib_validate_source() return drop reasons, instead of -reason.
---
include/net/dropreason-core.h | 10 ++++++++++
include/net/ip_fib.h | 12 ++++++++++++
net/ipv4/fib_frontend.c | 17 ++++++++++++-----
net/ipv4/ip_input.c | 4 +---
net/ipv4/route.c | 33 +++++++++++++++++++--------------
5 files changed, 54 insertions(+), 22 deletions(-)
diff --git a/include/net/dropreason-core.h b/include/net/dropreason-core.h
index d59bb96c5a02..62a60be1db84 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) \
@@ -373,6 +375,14 @@ 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/include/net/ip_fib.h b/include/net/ip_fib.h
index b6e44f4eaa4c..a113c11ab56b 100644
--- a/include/net/ip_fib.h
+++ b/include/net/ip_fib.h
@@ -452,6 +452,18 @@ int fib_validate_source(struct sk_buff *skb, __be32 src, __be32 dst,
dscp_t dscp, int oif, struct net_device *dev,
struct in_device *idev, u32 *itag);
+static inline enum skb_drop_reason
+fib_validate_source_reason(struct sk_buff *skb, __be32 src, __be32 dst,
+ dscp_t dscp, int oif, struct net_device *dev,
+ struct in_device *idev, u32 *itag)
+{
+ int err = fib_validate_source(skb, src, dst, dscp, oif, dev, idev,
+ itag);
+ if (err < 0)
+ return -err;
+ return SKB_NOT_DROPPED_YET;
+}
+
#ifdef CONFIG_IP_ROUTE_CLASSID
static inline int fib_num_tclassid_users(struct net *net)
{
diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c
index 53bd26315df5..99dddfab95b9 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. */
diff --git a/net/ipv4/ip_input.c b/net/ipv4/ip_input.c
index 89bb63da6852..c40a26972884 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 18a08b4f4a5a..3e7a3e947b7d 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -1669,7 +1669,7 @@ int ip_mc_validate_source(struct sk_buff *skb, __be32 daddr, __be32 saddr,
dscp_t dscp, struct net_device *dev,
struct in_device *in_dev, u32 *itag)
{
- int err;
+ enum skb_drop_reason reason;
/* Primary sanity checks. */
if (!in_dev)
@@ -1687,10 +1687,10 @@ int ip_mc_validate_source(struct sk_buff *skb, __be32 daddr, __be32 saddr,
ip_hdr(skb)->protocol != IPPROTO_IGMP)
return -EINVAL;
} else {
- err = fib_validate_source(skb, saddr, 0, dscp, 0, dev, in_dev,
- itag);
- if (err < 0)
- return err;
+ reason = fib_validate_source_reason(skb, saddr, 0, dscp, 0,
+ dev, in_dev, itag);
+ if (reason)
+ return -EINVAL;
}
return 0;
}
@@ -1788,6 +1788,7 @@ static int __mkroute_input(struct sk_buff *skb, const struct fib_result *res,
err = fib_validate_source(skb, saddr, daddr, dscp, 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);
@@ -2140,6 +2141,7 @@ int ip_route_use_hint(struct sk_buff *skb, __be32 daddr, __be32 saddr,
struct in_device *in_dev = __in_dev_get_rcu(dev);
struct rtable *rt = skb_rtable(hint);
struct net *net = dev_net(dev);
+ enum skb_drop_reason reason;
int err = -EINVAL;
u32 tag = 0;
@@ -2158,9 +2160,9 @@ int ip_route_use_hint(struct sk_buff *skb, __be32 daddr, __be32 saddr,
if (rt->rt_type != RTN_LOCAL)
goto skip_validate_source;
- err = fib_validate_source(skb, saddr, daddr, dscp, 0, dev, in_dev,
- &tag);
- if (err < 0)
+ reason = fib_validate_source_reason(skb, saddr, daddr, dscp, 0, dev,
+ in_dev, &tag);
+ if (reason)
goto martian_source;
skip_validate_source:
@@ -2202,6 +2204,7 @@ static int ip_route_input_slow(struct sk_buff *skb, __be32 daddr, __be32 saddr,
dscp_t dscp, struct net_device *dev,
struct fib_result *res)
{
+ enum skb_drop_reason reason = SKB_DROP_REASON_NOT_SPECIFIED;
struct in_device *in_dev = __in_dev_get_rcu(dev);
struct flow_keys *flkeys = NULL, _flkeys;
struct net *net = dev_net(dev);
@@ -2296,10 +2299,11 @@ static int ip_route_input_slow(struct sk_buff *skb, __be32 daddr, __be32 saddr,
goto brd_input;
}
+ err = -EINVAL;
if (res->type == RTN_LOCAL) {
- err = fib_validate_source(skb, saddr, daddr, dscp, 0, dev,
- in_dev, &itag);
- if (err < 0)
+ reason = fib_validate_source_reason(skb, saddr, daddr, dscp,
+ 0, dev, in_dev, &itag);
+ if (reason)
goto martian_source;
goto local_input;
}
@@ -2320,9 +2324,10 @@ out: return err;
goto e_inval;
if (!ipv4_is_zeronet(saddr)) {
- err = fib_validate_source(skb, saddr, 0, dscp, 0, dev, in_dev,
- &itag);
- if (err < 0)
+ err = -EINVAL;
+ reason = fib_validate_source_reason(skb, saddr, 0, dscp, 0,
+ dev, in_dev, &itag);
+ if (reason)
goto martian_source;
}
flags |= RTCF_BROADCAST;
--
2.39.5
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