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net: ip: make fib_validate_source() support drop reasons

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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@chinatelecom.cn>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
This commit is contained in:
Menglong Dong 2024-11-07 20:55:53 +08:00 committed by Paolo Abeni
parent 544070db6c
commit 37653a0b8a
5 changed files with 54 additions and 22 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
include/net/dropreason-core.h
View File

@ -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)

12
include/net/ip_fib.h
View File

@ -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)
{

17
net/ipv4/fib_frontend.c
View File

@ -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 @@ last_resort:
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. */

4
net/ipv4/ip_input.c
View File

@ -425,10 +425,8 @@ drop:
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;
}

33
net/ipv4/route.c
View File

@ -1682,7 +1682,7 @@ 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)
@ -1700,10 +1700,10 @@ 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;
}
@ -1801,6 +1801,7 @@ 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);
@ -2153,6 +2154,7 @@ 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;
@ -2171,9 +2173,9 @@ 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:
@ -2215,6 +2217,7 @@ 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);
@ -2309,10 +2312,11 @@ 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;
}
@ -2333,9 +2337,10 @@ brd_input:
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;