netfilter: nf_queue: fix reinject verdict handling [Linux 5.2]

netfilter: nf_queue: fix reinject verdict handling [Linux 5.2]

This Linux kernel change "netfilter: nf_queue: fix reinject verdict handling" is included in the Linux 5.2 release. This change is authored by Jagdish Motwani <jagdish.motwani [at] sophos.com> on Mon May 13 23:47:40 2019 +0530. The commit for this change in Linux stable tree is 946c0d8 (patch).

netfilter: nf_queue: fix reinject verdict handling

This patch fixes netfilter hook traversal when there are more than 1 hooks
returning NF_QUEUE verdict. When the first queue reinjects the packet,
'nf_reinject' starts traversing hooks with a proper hook_index. However,
if it again receives a NF_QUEUE verdict (by some other netfilter hook), it
queues the packet with a wrong hook_index. So, when the second queue
reinjects the packet, it re-executes hooks in between.

Fixes: 960632ece694 ("netfilter: convert hook list to an array")
Signed-off-by: Jagdish Motwani <jagdish.motwani@sophos.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

There is one line of Linux source code added/deleted in this change. Code changes to Linux kernel are as follows.

 net/netfilter/nf_queue.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/netfilter/nf_queue.c b/net/netfilter/nf_queue.c
index 9dc1d6e..b5b2be5 100644
--- a/net/netfilter/nf_queue.c
+++ b/net/netfilter/nf_queue.c
@@ -255,6 +255,7 @@ static unsigned int nf_iterate(struct sk_buff *skb,
 repeat:
        verdict = nf_hook_entry_hookfn(hook, skb, state);
        if (verdict != NF_ACCEPT) {
+           *index = i;
            if (verdict != NF_REPEAT)
                return verdict;
            goto repeat;

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