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SubjectRe: [PATCH] netfilter: fix CONFIG_NF_REJECT_IPV6=m link error
On Mon, Apr 09, 2018 at 04:43:40PM +0200, Arnd Bergmann wrote:
> On Mon, Apr 9, 2018 at 4:37 PM, Pablo Neira Ayuso <> wrote:
> > Hi Arnd,
> >
> > On Mon, Apr 09, 2018 at 12:53:12PM +0200, Arnd Bergmann wrote:
> >> We get a new link error with CONFIG_NFT_REJECT_INET=y and CONFIG_NF_REJECT_IPV6=m
> >
> > I think we can update NFT_REJECT_INET so it depends on NFT_REJECT_IPV4
> > and NFT_REJECT_IPV6. This doesn't allow here CONFIG_NFT_REJECT_INET=y
> >
> > I mean, just like we do with NFT_FIB_INET.
> That can only work if NFT_REJECT_INET can be made a 'tristate' symbol
> again, so that code gets built as a loadable module if
> > BTW, I think this problem has been is not related to the recent patch,
> > but something older that kbuild robot has triggered more easily for
> > some reason?
> 02c7b25e5f54 is the one that turned NF_TABLES_INET into a 'bool'
> symbol. NFT_REJECT depends on NF_TABLES_INET, so it used to
> restricted to a loadable module with IPV6=m, but can now be
> built-in, which causes that link error.

Still one more spin on this, I would like to see if we have a way to
fix this by simplifing things a bit.

Would this one I'm attaching would work?

Thanks for you patience.
From af07bc7ff5d34ce54e7913233912c058e6699e3c Mon Sep 17 00:00:00 2001
From: Pablo Neira Ayuso <>
Date: Fri, 13 Apr 2018 10:48:40 +0200
Subject: [PATCH] netfilter: CONFIG_NF_REJECT_IPV{4,6} becomes bool toggle

Arnd reports that we get a new link error with CONFIG_NFT_REJECT_INET=y
and CONFIG_NF_REJECT_IPV6=m after larger parts of the nftables modules
are linked together:

net/netfilter/nft_reject_inet.o: In function `nft_reject_inet_eval':
nft_reject_inet.c:(.text+0x17c): undefined reference to `nf_send_unreach6'
nft_reject_inet.c:(.text+0x190): undefined reference to `nf_send_reset6'

The problem is that with NF_TABLES_INET set, we implicitly try to use
the ipv6 version as well for NFT_REJECT, but when CONFIG_IPV6 is set to
a loadable module, it's impossible to reach that.

This patch fixes this problem by building-in nf_reject_ipv{4,6}.c, IPv6
symbol dependencies for the IPv6 reject infrastructure are located in
exthdrs_core.c, ip6_checksum.c and ip6_icmp.c which are also built-in,
so let's do the same to simplify this.

Fixes: 02c7b25e5f54 ("netfilter: nf_tables: build-in filter chain type")
Reported-by: Arnd Bergmann <>
Signed-off-by: Pablo Neira Ayuso <>
net/ipv4/netfilter/Kconfig | 3 +--
net/ipv6/netfilter/Kconfig | 3 +--
net/netfilter/Kconfig | 2 ++
3 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/net/ipv4/netfilter/Kconfig b/net/ipv4/netfilter/Kconfig
index 280048e1e395..3e4e0ae2a9a1 100644
--- a/net/ipv4/netfilter/Kconfig
+++ b/net/ipv4/netfilter/Kconfig
@@ -104,8 +104,7 @@ config NF_LOG_IPV4

- tristate "IPv4 packet rejection"
- default m if NETFILTER_ADVANCED=n
+ bool "IPv4 packet rejection"

config NF_NAT_IPV4
tristate "IPv4 NAT"
diff --git a/net/ipv6/netfilter/Kconfig b/net/ipv6/netfilter/Kconfig
index ccbfa83e4bb0..1e5d040a60b8 100644
--- a/net/ipv6/netfilter/Kconfig
+++ b/net/ipv6/netfilter/Kconfig
@@ -87,8 +87,7 @@ config NF_DUP_IPV6
packet to be rerouted to another destination.

- tristate "IPv6 packet rejection"
- default m if NETFILTER_ADVANCED=n
+ bool "IPv6 packet rejection"

config NF_LOG_IPV6
tristate "IPv6 packet logging"
diff --git a/net/netfilter/Kconfig b/net/netfilter/Kconfig
index 4189f574f5ec..d7b3272fe821 100644
--- a/net/netfilter/Kconfig
+++ b/net/netfilter/Kconfig
@@ -609,6 +609,8 @@ config NFT_REJECT

depends on NF_TABLES_INET
+ select NF_REJECT_IPV4
+ select NF_REJECT_IPV6
default NFT_REJECT

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