From: xu xin <[email protected]>
For now, no matter what error pointer ip_neigh_for_gw() returns,
ip_finish_output2() always return -EINVAL, which may mislead the upper
users.
For exemple, an application uses sendto to send an UDP packet, but when the
neighbor table overflows, sendto() will get a value of -EINVAL, and it will
cause users to waste a lot of time checking parameters for errors.
Return the real errno instead of -EINVAL.
Signed-off-by: xu xin <[email protected]>
Reviewed-by: Yang Yang <[email protected]>
Cc: Si Hao <[email protected]>
Cc: Dai Shixin <[email protected]>
Cc: Jiang Xuexin <[email protected]>
---
net/ipv4/ip_output.c | 9 ++++-----
1 file changed, 4 insertions(+), 5 deletions(-)
diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index 6ba1a0fafbaa..2d7cf083dff9 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -201,6 +201,7 @@ static int ip_finish_output2(struct net *net, struct sock *sk, struct sk_buff *s
unsigned int hh_len = LL_RESERVED_SPACE(dev);
struct neighbour *neigh;
bool is_v6gw = false;
+ int res;
if (rt->rt_type == RTN_MULTICAST) {
IP_UPD_PO_STATS(net, IPSTATS_MIB_OUTMCAST, skb->len);
@@ -214,8 +215,7 @@ static int ip_finish_output2(struct net *net, struct sock *sk, struct sk_buff *s
}
if (lwtunnel_xmit_redirect(dst->lwtstate)) {
- int res = lwtunnel_xmit(skb);
-
+ res = lwtunnel_xmit(skb);
if (res < 0 || res == LWTUNNEL_XMIT_DONE)
return res;
}
@@ -223,8 +223,6 @@ static int ip_finish_output2(struct net *net, struct sock *sk, struct sk_buff *s
rcu_read_lock();
neigh = ip_neigh_for_gw(rt, skb, &is_v6gw);
if (!IS_ERR(neigh)) {
- int res;
-
sock_confirm_neigh(skb, neigh);
/* if crossing protocols, can not use the cached header */
res = neigh_output(neigh, skb, is_v6gw);
@@ -236,7 +234,8 @@ static int ip_finish_output2(struct net *net, struct sock *sk, struct sk_buff *s
net_dbg_ratelimited("%s: No header cache and no neighbour!\n",
__func__);
kfree_skb_reason(skb, SKB_DROP_REASON_NEIGH_CREATEFAIL);
- return -EINVAL;
+ res = PTR_ERR(neigh);
+ return res;
}
static int ip_finish_output_gso(struct net *net, struct sock *sk,
--
2.15.2
On 04/08/2023 09:48, [email protected] wrote:
> From: xu xin <[email protected]>
>
> For now, no matter what error pointer ip_neigh_for_gw() returns,
> ip_finish_output2() always return -EINVAL, which may mislead the upper
> users.
>
> For exemple, an application uses sendto to send an UDP packet, but when the
> neighbor table overflows, sendto() will get a value of -EINVAL, and it will
> cause users to waste a lot of time checking parameters for errors.
>
> Return the real errno instead of -EINVAL.
>
> Signed-off-by: xu xin <[email protected]>
> Reviewed-by: Yang Yang <[email protected]>
> Cc: Si Hao <[email protected]>
> Cc: Dai Shixin <[email protected]>
> Cc: Jiang Xuexin <[email protected]>
> ---
> net/ipv4/ip_output.c | 9 ++++-----
> 1 file changed, 4 insertions(+), 5 deletions(-)
>
> diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
> index 6ba1a0fafbaa..2d7cf083dff9 100644
> --- a/net/ipv4/ip_output.c
> +++ b/net/ipv4/ip_output.c
> @@ -201,6 +201,7 @@ static int ip_finish_output2(struct net *net, struct sock *sk, struct sk_buff *s
> unsigned int hh_len = LL_RESERVED_SPACE(dev);
> struct neighbour *neigh;
> bool is_v6gw = false;
> + int res;
>
> if (rt->rt_type == RTN_MULTICAST) {
> IP_UPD_PO_STATS(net, IPSTATS_MIB_OUTMCAST, skb->len);
> @@ -214,8 +215,7 @@ static int ip_finish_output2(struct net *net, struct sock *sk, struct sk_buff *s
> }
>
> if (lwtunnel_xmit_redirect(dst->lwtstate)) {
> - int res = lwtunnel_xmit(skb);
> -
> + res = lwtunnel_xmit(skb);
> if (res < 0 || res == LWTUNNEL_XMIT_DONE)
> return res;
> }
> @@ -223,8 +223,6 @@ static int ip_finish_output2(struct net *net, struct sock *sk, struct sk_buff *s
> rcu_read_lock();
> neigh = ip_neigh_for_gw(rt, skb, &is_v6gw);
> if (!IS_ERR(neigh)) {
> - int res;
> -
> sock_confirm_neigh(skb, neigh);
> /* if crossing protocols, can not use the cached header */
> res = neigh_output(neigh, skb, is_v6gw);
> @@ -236,7 +234,8 @@ static int ip_finish_output2(struct net *net, struct sock *sk, struct sk_buff *s
> net_dbg_ratelimited("%s: No header cache and no neighbour!\n",
> __func__);
> kfree_skb_reason(skb, SKB_DROP_REASON_NEIGH_CREATEFAIL);
> - return -EINVAL;
> + res = PTR_ERR(neigh);
> + return res;
I believe this part could be written as
- return -EINVAL;
+ return PTR_ERR(neigh);
and there is no need to change the code is other places. This will be
easier to track/backport.
> }
>
> static int ip_finish_output_gso(struct net *net, struct sock *sk,
>> @@ -236,7 +234,8 @@ static int ip_finish_output2(struct net *net, struct sock *sk, struct sk_buff *s
>> net_dbg_ratelimited("%s: No header cache and no neighbour!\n",
>> __func__);
>> kfree_skb_reason(skb, SKB_DROP_REASON_NEIGH_CREATEFAIL);
>> - return -EINVAL;
>> + res = PTR_ERR(neigh);
>> + return res;
>
>I believe this part could be written as
>
>- return -EINVAL;
>+ return PTR_ERR(neigh);
>
>
>and there is no need to change the code is other places. This will be
>easier to track/backport.
Sure, I initially wrote the same thing with you, but considering the convenience of maintainer review,
I deliberately modified some other parts of the code to present a clear context of the core
modifications.
From your reply, I can see you agree with my key idea of this patch, so I have sent a v2 patch[1] according
to your view.
[1] https://lore.kernel.org/all/[email protected]/