[PATCH xtables] nft: exit in case we can't fetch current genid

[Florian Westphal]

When running iptables -nL as non-root user, iptables would loop indefinitely.

With this change, it will fail with
iptables v1.8.3 (nf_tables): Could not fetch rule set generation id: Permission 
denied (you must be root)

Reported-by: Amish <anon.am...@gmail.com>
Signed-off-by: Florian Westphal <f...@strlen.de>
---
 iptables/nft.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/iptables/nft.c b/iptables/nft.c
index e927d1db2b42..8f0d5e664eca 100644
--- a/iptables/nft.c
+++ b/iptables/nft.c
@@ -82,13 +82,19 @@ out:
        return MNL_CB_ERROR;
 }
 
-static int mnl_genid_get(struct nft_handle *h, uint32_t *genid)
+static void mnl_genid_get(struct nft_handle *h, uint32_t *genid)
 {
        char buf[MNL_SOCKET_BUFFER_SIZE];
        struct nlmsghdr *nlh;
+       int ret;
 
        nlh = nftnl_nlmsg_build_hdr(buf, NFT_MSG_GETGEN, 0, 0, h->seq);
-       return mnl_talk(h, nlh, genid_cb, genid);
+       ret = mnl_talk(h, nlh, genid_cb, genid);
+       if (ret == 0)
+               return;
+
+       xtables_error(RESOURCE_PROBLEM,
+                     "Could not fetch rule set generation id: %s\n", 
nft_strerror(errno));
 }
 
 int mnl_talk(struct nft_handle *h, struct nlmsghdr *nlh,
-- 
2.21.0