[PATCH net-next 6/7] net: ip: make ip_mc_validate_source() return drop reason

From: Menglong Dong
Date: Tue Oct 01 2024 - 02:03:35 EST


Make ip_mc_validate_source() return drop reason, and adjust the call of
it in ip_route_input_mc().

Another caller of it is ip_rcv_finish_core->udp_v4_early_demux, and the
errno is not checked in detail, so we don't do more adjustment for it.

Signed-off-by: Menglong Dong <dongml2@xxxxxxxxxxxxxxx>
---
include/net/route.h | 7 ++++---
net/ipv4/route.c | 33 ++++++++++++++++++---------------
2 files changed, 22 insertions(+), 18 deletions(-)

diff --git a/include/net/route.h b/include/net/route.h
index cb9f31080517..cd0f585dacf0 100644
--- a/include/net/route.h
+++ b/include/net/route.h
@@ -198,9 +198,10 @@ static inline struct rtable *ip_route_output_gre(struct net *net, struct flowi4
fl4->fl4_gre_key = gre_key;
return ip_route_output_key(net, fl4);
}
-int ip_mc_validate_source(struct sk_buff *skb, __be32 daddr, __be32 saddr,
- u8 tos, struct net_device *dev,
- struct in_device *in_dev, u32 *itag);
+enum skb_drop_reason
+ip_mc_validate_source(struct sk_buff *skb, __be32 daddr, __be32 saddr,
+ u8 tos, struct net_device *dev,
+ struct in_device *in_dev, u32 *itag);
int ip_route_input_noref(struct sk_buff *skb, __be32 dst, __be32 src,
u8 tos, struct net_device *devin,
enum skb_drop_reason *reason);
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index f577012985c5..89f97637af20 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -1665,34 +1665,37 @@ struct rtable *rt_dst_clone(struct net_device *dev, struct rtable *rt)
EXPORT_SYMBOL(rt_dst_clone);

/* called in rcu_read_lock() section */
-int ip_mc_validate_source(struct sk_buff *skb, __be32 daddr, __be32 saddr,
- u8 tos, struct net_device *dev,
- struct in_device *in_dev, u32 *itag)
+enum skb_drop_reason
+ip_mc_validate_source(struct sk_buff *skb, __be32 daddr, __be32 saddr,
+ u8 tos, struct net_device *dev,
+ struct in_device *in_dev, u32 *itag)
{
int err;

/* Primary sanity checks. */
if (!in_dev)
- return -EINVAL;
+ return SKB_DROP_REASON_NOT_SPECIFIED;

- if (ipv4_is_multicast(saddr) || ipv4_is_lbcast(saddr) ||
- skb->protocol != htons(ETH_P_IP))
- return -EINVAL;
+ if (ipv4_is_multicast(saddr) || ipv4_is_lbcast(saddr))
+ return SKB_DROP_REASON_IP_INVALID_SOURCE;
+
+ if (skb->protocol != htons(ETH_P_IP))
+ return SKB_DROP_REASON_INVALID_PROTO;

if (ipv4_is_loopback(saddr) && !IN_DEV_ROUTE_LOCALNET(in_dev))
- return -EINVAL;
+ return SKB_DROP_REASON_IP_LOCALNET;

if (ipv4_is_zeronet(saddr)) {
if (!ipv4_is_local_multicast(daddr) &&
ip_hdr(skb)->protocol != IPPROTO_IGMP)
- return -EINVAL;
+ return SKB_DROP_REASON_IP_INVALID_SOURCE;
} else {
err = fib_validate_source(skb, saddr, 0, tos, 0, dev,
in_dev, itag);
if (err < 0)
- return -EINVAL;
+ return -err;
}
- return 0;
+ return SKB_NOT_DROPPED_YET;
}

/* called in rcu_read_lock() section */
@@ -1702,13 +1705,13 @@ ip_route_input_mc(struct sk_buff *skb, __be32 daddr, __be32 saddr,
{
struct in_device *in_dev = __in_dev_get_rcu(dev);
unsigned int flags = RTCF_MULTICAST;
+ enum skb_drop_reason reason;
struct rtable *rth;
u32 itag = 0;
- int err;

- err = ip_mc_validate_source(skb, daddr, saddr, tos, dev, in_dev, &itag);
- if (err)
- return SKB_DROP_REASON_NOT_SPECIFIED;
+ reason = ip_mc_validate_source(skb, daddr, saddr, tos, dev, in_dev, &itag);
+ if (reason)
+ return reason;

if (our)
flags |= RTCF_LOCAL;
--
2.39.5