diff mbox series

[RESEND,net-next,v4,6/9] net: ip: make ip_route_input_noref() return drop reasons

Message ID 20241030014145.1409628-7-dongml2@chinatelecom.cn (mailing list archive)
State Superseded
Delegated to: Netdev Maintainers
Headers show
Series net: ip: add drop reasons to input route | expand

Checks

Context Check Description
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for net-next
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 14 this patch: 14
netdev/build_tools success Errors and warnings before: 0 (+0) this patch: 0 (+0)
netdev/cc_maintainers success CCed 9 of 9 maintainers
netdev/build_clang success Errors and warnings before: 19 this patch: 19
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 1819 this patch: 1819
netdev/checkpatch warning WARNING: From:/Signed-off-by: email address mismatch: 'From: Menglong Dong <menglong8.dong@gmail.com>' != 'Signed-off-by: Menglong Dong <dongml2@chinatelecom.cn>'
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 1 this patch: 1
netdev/source_inline success Was 0 now: 0
netdev/contest success net-next-2024-11-03--21-00 (tests: 781)

Commit Message

Menglong Dong Oct. 30, 2024, 1:41 a.m. UTC 
In this commit, we make ip_route_input_noref() return drop reasons, which
come from ip_route_input_rcu().

We need adjust the callers of ip_route_input_noref() to make sure the
return value of ip_route_input_noref() is used properly.

The errno that ip_route_input_noref() returns comes from ip_route_input
and bpf_lwt_input_reroute in the origin logic, and we make them return
-EINVAL on error instead. In the following patch, we will make
ip_route_input() returns drop reasons too.

Signed-off-by: Menglong Dong <dongml2@chinatelecom.cn>
---
v4:
- introduce the variable "reason" in bpf_lwt_input_reroute() to make
  things clear
---
 include/net/route.h    | 15 ++++++++-------
 net/core/lwt_bpf.c     |  6 ++++--
 net/ipv4/ip_fragment.c | 12 +++++++-----
 net/ipv4/ip_input.c    |  7 ++++---
 net/ipv4/route.c       |  7 ++++---
 5 files changed, 27 insertions(+), 20 deletions(-)

Comments

Paolo Abeni Nov. 5, 2024, 11:22 a.m. UTC | #1 
Hi,

On 10/30/24 02:41, Menglong Dong wrote:
> @@ -175,10 +175,12 @@ static void ip_expire(struct timer_list *t)
>  
>  	/* skb has no dst, perform route lookup again */
>  	iph = ip_hdr(head);
> -	err = ip_route_input_noref(head, iph->daddr, iph->saddr, ip4h_dscp(iph),
> -				   head->dev);
> -	if (err)
> +	reason = ip_route_input_noref(head, iph->daddr, iph->saddr,
> +				      ip4h_dscp(iph), head->dev);
> +	if (reason)
>  		goto out;
> +	else
> +		reason = SKB_DROP_REASON_FRAG_REASM_TIMEOUT;

I think the else branch above is confusing - and unneeded.

Please move the assignment after the comment below, so it's clear why we
get a TIMEOUT drop reason.

Thanks,

Paolo
Menglong Dong Nov. 6, 2024, 9:40 a.m. UTC | #2 
On Tue, Nov 5, 2024 at 7:22 PM Paolo Abeni <pabeni@redhat.com> wrote:
>
> Hi,
>
> On 10/30/24 02:41, Menglong Dong wrote:
> > @@ -175,10 +175,12 @@ static void ip_expire(struct timer_list *t)
> >
> >       /* skb has no dst, perform route lookup again */
> >       iph = ip_hdr(head);
> > -     err = ip_route_input_noref(head, iph->daddr, iph->saddr, ip4h_dscp(iph),
> > -                                head->dev);
> > -     if (err)
> > +     reason = ip_route_input_noref(head, iph->daddr, iph->saddr,
> > +                                   ip4h_dscp(iph), head->dev);
> > +     if (reason)
> >               goto out;
> > +     else
> > +             reason = SKB_DROP_REASON_FRAG_REASM_TIMEOUT;
>
> I think the else branch above is confusing - and unneeded.

Yeah, that makes sense.

> Please move the assignment after the comment below, so it's clear why we
> get a TIMEOUT drop reason.

Okay!

Thanks!
Menglong Dong

>
> Thanks,
>
> Paolo
>
diff mbox series

Patch

diff --git a/include/net/route.h b/include/net/route.h
index a828a17a6313..11674f7c6be6 100644
--- a/include/net/route.h
+++ b/include/net/route.h
@@ -203,8 +203,9 @@  enum skb_drop_reason
 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 ip_route_input_noref(struct sk_buff *skb, __be32 daddr, __be32 saddr,
-			 dscp_t dscp, struct net_device *dev);
+enum skb_drop_reason
+ip_route_input_noref(struct sk_buff *skb, __be32 daddr, __be32 saddr,
+		     dscp_t dscp, struct net_device *dev);
 int ip_route_use_hint(struct sk_buff *skb, __be32 daddr, __be32 saddr,
 		      dscp_t dscp, struct net_device *dev,
 		      const struct sk_buff *hint);
@@ -212,18 +213,18 @@  int ip_route_use_hint(struct sk_buff *skb, __be32 daddr, __be32 saddr,
 static inline int ip_route_input(struct sk_buff *skb, __be32 dst, __be32 src,
 				 dscp_t dscp, struct net_device *devin)
 {
-	int err;
+	enum skb_drop_reason reason;
 
 	rcu_read_lock();
-	err = ip_route_input_noref(skb, dst, src, dscp, devin);
-	if (!err) {
+	reason = ip_route_input_noref(skb, dst, src, dscp, devin);
+	if (!reason) {
 		skb_dst_force(skb);
 		if (!skb_dst(skb))
-			err = -EINVAL;
+			reason = SKB_DROP_REASON_NOT_SPECIFIED;
 	}
 	rcu_read_unlock();
 
-	return err;
+	return reason ? -EINVAL : 0;
 }
 
 void ipv4_update_pmtu(struct sk_buff *skb, struct net *net, u32 mtu, int oif,
diff --git a/net/core/lwt_bpf.c b/net/core/lwt_bpf.c
index e0ca24a58810..8a78bff53b2c 100644
--- a/net/core/lwt_bpf.c
+++ b/net/core/lwt_bpf.c
@@ -88,6 +88,7 @@  static int run_lwt_bpf(struct sk_buff *skb, struct bpf_lwt_prog *lwt,
 
 static int bpf_lwt_input_reroute(struct sk_buff *skb)
 {
+	enum skb_drop_reason reason;
 	int err = -EINVAL;
 
 	if (skb->protocol == htons(ETH_P_IP)) {
@@ -96,8 +97,9 @@  static int bpf_lwt_input_reroute(struct sk_buff *skb)
 
 		dev_hold(dev);
 		skb_dst_drop(skb);
-		err = ip_route_input_noref(skb, iph->daddr, iph->saddr,
-					   ip4h_dscp(iph), dev);
+		reason = ip_route_input_noref(skb, iph->daddr, iph->saddr,
+					      ip4h_dscp(iph), dev);
+		err = reason ? -EINVAL : 0;
 		dev_put(dev);
 	} else if (skb->protocol == htons(ETH_P_IPV6)) {
 		skb_dst_drop(skb);
diff --git a/net/ipv4/ip_fragment.c b/net/ipv4/ip_fragment.c
index 48e2810f1f27..52b991e976ba 100644
--- a/net/ipv4/ip_fragment.c
+++ b/net/ipv4/ip_fragment.c
@@ -132,12 +132,12 @@  static bool frag_expire_skip_icmp(u32 user)
  */
 static void ip_expire(struct timer_list *t)
 {
+	enum skb_drop_reason reason = SKB_DROP_REASON_FRAG_REASM_TIMEOUT;
 	struct inet_frag_queue *frag = from_timer(frag, t, timer);
 	const struct iphdr *iph;
 	struct sk_buff *head = NULL;
 	struct net *net;
 	struct ipq *qp;
-	int err;
 
 	qp = container_of(frag, struct ipq, q);
 	net = qp->q.fqdir->net;
@@ -175,10 +175,12 @@  static void ip_expire(struct timer_list *t)
 
 	/* skb has no dst, perform route lookup again */
 	iph = ip_hdr(head);
-	err = ip_route_input_noref(head, iph->daddr, iph->saddr, ip4h_dscp(iph),
-				   head->dev);
-	if (err)
+	reason = ip_route_input_noref(head, iph->daddr, iph->saddr,
+				      ip4h_dscp(iph), head->dev);
+	if (reason)
 		goto out;
+	else
+		reason = SKB_DROP_REASON_FRAG_REASM_TIMEOUT;
 
 	/* Only an end host needs to send an ICMP
 	 * "Fragment Reassembly Timeout" message, per RFC792.
@@ -195,7 +197,7 @@  static void ip_expire(struct timer_list *t)
 	spin_unlock(&qp->q.lock);
 out_rcu_unlock:
 	rcu_read_unlock();
-	kfree_skb_reason(head, SKB_DROP_REASON_FRAG_REASM_TIMEOUT);
+	kfree_skb_reason(head, reason);
 	ipq_put(qp);
 }
 
diff --git a/net/ipv4/ip_input.c b/net/ipv4/ip_input.c
index c40a26972884..513eb0c6435a 100644
--- a/net/ipv4/ip_input.c
+++ b/net/ipv4/ip_input.c
@@ -362,10 +362,11 @@  static int ip_rcv_finish_core(struct net *net, struct sock *sk,
 	 *	how the packet travels inside Linux networking.
 	 */
 	if (!skb_valid_dst(skb)) {
-		err = ip_route_input_noref(skb, iph->daddr, iph->saddr,
-					   ip4h_dscp(iph), dev);
-		if (unlikely(err))
+		drop_reason = ip_route_input_noref(skb, iph->daddr, iph->saddr,
+						   ip4h_dscp(iph), dev);
+		if (unlikely(drop_reason))
 			goto drop_error;
+		drop_reason = SKB_DROP_REASON_NOT_SPECIFIED;
 	} else {
 		struct in_device *in_dev = __in_dev_get_rcu(dev);
 
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 1926a8a1a83a..ce1201dbf464 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -2487,8 +2487,9 @@  ip_route_input_rcu(struct sk_buff *skb, __be32 daddr, __be32 saddr,
 	return ip_route_input_slow(skb, daddr, saddr, dscp, dev, res);
 }
 
-int ip_route_input_noref(struct sk_buff *skb, __be32 daddr, __be32 saddr,
-			 dscp_t dscp, struct net_device *dev)
+enum skb_drop_reason ip_route_input_noref(struct sk_buff *skb, __be32 daddr,
+					  __be32 saddr, dscp_t dscp,
+					  struct net_device *dev)
 {
 	enum skb_drop_reason reason;
 	struct fib_result res;
@@ -2497,7 +2498,7 @@  int ip_route_input_noref(struct sk_buff *skb, __be32 daddr, __be32 saddr,
 	reason = ip_route_input_rcu(skb, daddr, saddr, dscp, dev, &res);
 	rcu_read_unlock();
 
-	return reason ? -EINVAL : 0;
+	return reason;
 }
 EXPORT_SYMBOL(ip_route_input_noref);