[PATCH net] ipv6: exthdrs: do not blindly use init_net

From: Eric Dumazet <edumazet@google.com>

I see no reason why max_dst_opts_cnt and max_hbh_opts_cnt
are fetched from the initial net namespace.

The other sysctls (max_dst_opts_len & max_hbh_opts_len)
are in fact already using the current ns.

Note: it is not clear why ipv6_destopt_rcv() use two ways to
get to the netns :

 1) dev_net(dst->dev)
    Originally used to increment IPSTATS_MIB_INHDRERRORS

 2) dev_net(skb->dev)
     Tom used this variant in his patch.

Maybe this calls to use ipv6_skb_net() instead ?

Fixes: 47d3d7ac656a ("ipv6: Implement limits on Hop-by-Hop and Destination options")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Tom Herbert <redacted>
Cc: Coco Li <redacted>
---
 net/ipv6/exthdrs.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/ipv6/exthdrs.c b/net/ipv6/exthdrs.c
index 56e479d158b7c069000f77db88f468d9414ff7e5..6f7da8f3e2e5849f917853984c69bf02a0f1e27c 100644
--- a/net/ipv6/exthdrs.c
+++ b/net/ipv6/exthdrs.c

@@ -306,7 +306,7 @@ static int ipv6_destopt_rcv(struct sk_buff *skb)
 #endif
 
 	if (ip6_parse_tlv(tlvprocdestopt_lst, skb,
-			  init_net.ipv6.sysctl.max_dst_opts_cnt)) {
+			  net->ipv6.sysctl.max_dst_opts_cnt)) {
 		skb->transport_header += extlen;
 		opt = IP6CB(skb);
 #if IS_ENABLED(CONFIG_IPV6_MIP6)

@@ -1037,7 +1037,7 @@ int ipv6_parse_hopopts(struct sk_buff *skb)
 
 	opt->flags |= IP6SKB_HOPBYHOP;
 	if (ip6_parse_tlv(tlvprochopopt_lst, skb,
-			  init_net.ipv6.sysctl.max_hbh_opts_cnt)) {
+			  net->ipv6.sysctl.max_hbh_opts_cnt)) {
 		skb->transport_header += extlen;
 		opt = IP6CB(skb);
 		opt->nhoff = sizeof(struct ipv6hdr);

-- 
2.32.0.288.g62a8d224e6-goog

Hello:

This patch was applied to netdev/net.git (refs/heads/master):

On Wed, 23 Jun 2021 08:27:00 -0700 you wrote:

From: Eric Dumazet <edumazet@google.com>

I see no reason why max_dst_opts_cnt and max_hbh_opts_cnt
are fetched from the initial net namespace.

The other sysctls (max_dst_opts_len & max_hbh_opts_len)
are in fact already using the current ns.

[...]

Here is the summary with links:
  - [net] ipv6: exthdrs: do not blindly use init_net
    https://git.kernel.org/netdev/net/c/bcc3f2a829b9

You are awesome, thank you!
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