Re: iptables-nft: Wrong payload merge of rule filter - "! --sport xx ! --dport xx"

[Florian Westphal <fw@xxxxxxxxx>]

Sriram Rajagopalan <bglsriram@xxxxxxxxx> wrote:
> diff --git a/src/rule.c b/src/rule.c
> index 342c43fb..5def185d 100644
> --- a/src/rule.c
> +++ b/src/rule.c
> @@ -2661,8 +2661,13 @@ static void payload_do_merge(struct stmt *sa[],
> unsigned int n)
>         for (j = 0, i = 1; i < n; i++) {
>                 stmt = sa[i];
>                 this = stmt->expr;
> -
> -               if (!payload_can_merge(last->left, this->left) ||
> +               /* We should not be merging two OP_NEQs. For example -
> +                * tcp sport != 22 tcp dport != 23 should not result in
> +                * [ payload load 4b @ transport header + 0 => reg 1 ]
> +                * [ cmp neq reg 1 0x17001600 ]
> +                */
> +               if (this->op == OP_NEQ ||
> +                   !payload_can_merge(last->left, this->left) ||
>                     !relational_ops_match(last, this)) {
>                         last = this;
>                         j = i;
> 
> Please review the patches above and provide your feedback. Please let
> me know of any questions/clarifications.


Probably better to do:

diff --git a/src/rule.c b/src/rule.c
--- a/src/rule.c
+++ b/src/rule.c
@@ -2766,7 +2766,6 @@ static void stmt_reduce(const struct rule *rule)
                        switch (stmt->expr->op) {
                        case OP_EQ:
                        case OP_IMPLICIT:
-                       case OP_NEQ:
                                break;
                        default:
                                continue;