Re: [PATCH] netfliter: xtables: fix typo causing some targets to not load on IPv6

Hi Ilya,

(+ add people/ML back in cc)

On 23/10/2024 14:11, Ilya K wrote:

quoted

Hi Ilya,

On 18/10/2024 17:45, Ilya Katsnelson wrote:

quoted

These were added with the wrong family in 4cdc55e, which seems
to just have been a typo, but now ip6tables rules with --set-mark
don't work anymore, which is pretty bad.

Funny, with this patch, now the v4 version doesn't work any more, which
is pretty bad as well ;-)

More seriously, it looks like your patch broke MPTCP selftests:


https://netdev-3.bots.linux.dev/vmksft-mptcp-dbg/results/826643/1-mptcp-join-sh/stdout

Two tests are now failing, because they can no longer add a mark:

quoted

# iptables -t mangle -A OUTPUT -j MARK --set-mark 1
Warning: Extension MARK revision 0 not supported, missing kernel module?
iptables v1.8.10 (nf_tables):  RULE_APPEND failed (No such file or directory): rule in chain OUTPUT

Please see below:

quoted

diff --git a/net/netfilter/xt_NFLOG.c b/net/netfilter/xt_NFLOG.c
index d80abd6ccaf8f71fa70605fef7edada827a19ceb..6dcf4bc7e30b2ae364a1cd9ac8df954a90905c52 100644
--- a/net/netfilter/xt_NFLOG.c
+++ b/net/netfilter/xt_NFLOG.c

@@ -79,7 +79,7 @@ static struct xt_target nflog_tg_reg[] __read_mostly = {
 	{
 		.name       = "NFLOG",
 		.revision   = 0,
-		.family     = NFPROTO_IPV4,
+		.family     = NFPROTO_IPV6,

Here, by setting the family to v6 instead of v4, we now have two targets
that are exactly the same, both for v6:

quoted

  67   │ static struct xt_target nflog_tg_reg[] __read_mostly = {
  68   │     {
  69   │         .name       = "NFLOG",
  70   │         .revision   = 0,
  71   │         .family     = NFPROTO_IPV6,  /* <== The line you modified */
  72   │         .checkentry = nflog_tg_check,
  73   │         .destroy    = nflog_tg_destroy,
  74   │         .target     = nflog_tg,
  75   │         .targetsize = sizeof(struct xt_nflog_info),
  76   │         .me         = THIS_MODULE,
  77   │     },
  78   │ #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
  79   │     {
  80   │         .name       = "NFLOG",
  81   │         .revision   = 0,
  82   │         .family     = NFPROTO_IPV6,  /* <== v6 was already there */
  83   │         .checkentry = nflog_tg_check,
  84   │         .destroy    = nflog_tg_destroy,
  85   │         .target     = nflog_tg,
  86   │         .targetsize = sizeof(struct xt_nflog_info),
  87   │         .me         = THIS_MODULE,
  88   │     },
  89   │ #endif
  90   │ };

Are you sure you didn't have the bug you mentioned because your kernel
config doesn't have CONFIG_IP6_NF_IPTABLES?

quoted

 		.checkentry = nflog_tg_check,
 		.destroy    = nflog_tg_destroy,
 		.target     = nflog_tg,

diff --git a/net/netfilter/xt_mark.c b/net/netfilter/xt_mark.c
index f76fe04fc9a4e19f18ac323349ba6f22a00eafd7..65b965ca40ea7ea5d9feff381b433bf267a424c4 100644
--- a/net/netfilter/xt_mark.c
+++ b/net/netfilter/xt_mark.c

@@ -62,7 +62,7 @@ static struct xt_target mark_tg_reg[] __read_mostly = {
 	{
 		.name           = "MARK",
 		.revision       = 2,
-		.family         = NFPROTO_IPV4,
+		.family         = NFPROTO_IPV6,

Same here.

So I think this patch is not needed, right?

quoted

 		.target         = mark_tg,
 		.targetsize     = sizeof(struct xt_mark_tginfo2),
 		.me             = THIS_MODULE,

---
base-commit: 75aa74d52f43e75d0beb20572f98529071b700e5
change-id: 20241018-xtables-typos-dfeadb8b122d

Best regards,

Cheers,
Matt

The patch never got merged, but Pablo's very similar patch did. Are you
by any chance applying my changes on top of a tree that also contains
his?

Thank you for this reply!

Oh, sorry, I see the issue now, just an unlucky situation:

- On one hand, and probably because the issue was visible on stable too,
Pablo sent a new version changing the author and the title ("not to
load" vs "to not load") [1]. Because of that, the bot didn't mark the
previous version as superseded.

- On the other hand, the CI tried to apply all the pending patches,
including this patch here: when git tried to apply this patch, it
managed to find the exact same context a bit before, and then modified
the wrong line [2].

The two combined resulted in the CI trying to validate a buggy patch not
doing what it was intended to do.

From what I understood, Paolo is changing the status of [1] and even [3]
on Patchwork, and soon the CI will stop using the wrong patch.

[1]
https://patchwork.kernel.org/project/netdevbpf/patch/20241021094536.81487-3-pablo@netfilter.org/
[2]
https://github.com/linux-netdev/testing/commit/096e5d7e7d38271b6353ecd197e8ec00a01dbfd3
[3]
https://patchwork.kernel.org/project/netdevbpf/patch/20241018162517.39154-1-ignat@cloudflare.com/

Cheers,
Matt
-- 
Sponsored by the NGI0 Core fund.