[PATCH v13 nf-next 0/3] conntrack: bridge: add double vlan, pppoe and pppoe-in-q

[PATCH v13 nf-next 0/3] conntrack: bridge: add double vlan, pppoe and pppoe-in-q

[Eric Woudstra]

Conntrack bridge only tracks untagged and 802.1q.

To make the bridge-fastpath experience more similar to the
forward-fastpath experience, add double vlan, pppoe and pppoe-in-q
tagged packets to bridge conntrack and to bridge filter chain.

Changes in v13:

- Do not use pull/push before/after calling nf_conntrack_in() or
   nft_do_chain().
- Add patch to correct calculating checksum when skb->data !=
   skb_network_header(skb).

Changes in v12:

- Only allow tracking this traffic when a conntrack zone is set.
- nf_ct_bridge_pre(): skb pull/push without touching the checksum,
   because the pull is always restored with push.
- nft_do_chain_bridge(): handle the extra header similar to
   nf_ct_bridge_pre(), using pull/push.

Changes in v11:

- nft_do_chain_bridge(): Proper readout of encapsulated proto.
- nft_do_chain_bridge(): Use skb_set_network_header() instead of thoff.
- removed test script, it is now in separate patch.

v10 split from patch-set: bridge-fastpath and related improvements v9

Eric Woudstra (3):
  netfilter: utils: nf_checksum(_partial) correct data!=networkheader
  netfilter: bridge: Add conntrack double vlan and pppoe
  netfilter: nft_chain_filter: Add bridge double vlan and pppoe

 net/bridge/netfilter/nf_conntrack_bridge.c | 88 ++++++++++++++++++----
 net/netfilter/nft_chain_filter.c           | 52 ++++++++++++-
 net/netfilter/utils.c                      | 22 ++++--
 3 files changed, 139 insertions(+), 23 deletions(-)

-- 
2.47.1

[PATCH v13 nf-next 1/3] netfilter: utils: nf_checksum(_partial) correct data!=networkheader

[Eric Woudstra]

In the conntrack hook it may not always be the case that:
skb_network_header(skb) == skb->data.

This is problematic when L4 function nf_conntrack_handle_packet()
is accessing L3 data. This function uses thoff and ip_hdr()
to finds it's data. But it also calculates the checksum.
nf_checksum() and nf_checksum_partial() both use lower skb-checksum
functions that are based on using skb->data.

When skb_network_header(skb) != skb->data, adjust accordingly,
so that the checksum is calculated correctly.

Signed-off-by: Eric Woudstra <ericwouds@gmail.com>
---
 net/netfilter/utils.c | 22 ++++++++++++++++------
 1 file changed, 16 insertions(+), 6 deletions(-)

diff --git a/net/netfilter/utils.c b/net/netfilter/utils.c
index 008419db815a..daee035c25b8 100644
--- a/net/netfilter/utils.c
+++ b/net/netfilter/utils.c
@@ -124,16 +124,21 @@ __sum16 nf_checksum(struct sk_buff *skb, unsigned int hook,
 		    unsigned int dataoff, u8 protocol,
 		    unsigned short family)
 {
+	unsigned int nhpull = skb_network_header(skb) - skb->data;
 	__sum16 csum = 0;
 
+	if (!pskb_may_pull(skb, nhpull))
+		return -ENOMEM;
+	__skb_pull(skb, nhpull);
 	switch (family) {
 	case AF_INET:
-		csum = nf_ip_checksum(skb, hook, dataoff, protocol);
+		csum = nf_ip_checksum(skb, hook, dataoff - nhpull, protocol);
 		break;
 	case AF_INET6:
-		csum = nf_ip6_checksum(skb, hook, dataoff, protocol);
+		csum = nf_ip6_checksum(skb, hook, dataoff - nhpull, protocol);
 		break;
 	}
+	__skb_push(skb, nhpull);
 
 	return csum;
 }
@@ -143,18 +148,23 @@ __sum16 nf_checksum_partial(struct sk_buff *skb, unsigned int hook,
 			    unsigned int dataoff, unsigned int len,
 			    u8 protocol, unsigned short family)
 {
+	unsigned int nhpull = skb_network_header(skb) - skb->data;
 	__sum16 csum = 0;
 
+	if (!pskb_may_pull(skb, nhpull))
+		return -ENOMEM;
+	__skb_pull(skb, nhpull);
 	switch (family) {
 	case AF_INET:
-		csum = nf_ip_checksum_partial(skb, hook, dataoff, len,
-					      protocol);
+		csum = nf_ip_checksum_partial(skb, hook, dataoff - nhpull,
+					      len, protocol);
 		break;
 	case AF_INET6:
-		csum = nf_ip6_checksum_partial(skb, hook, dataoff, len,
-					       protocol);
+		csum = nf_ip6_checksum_partial(skb, hook, dataoff - nhpull,
+					       len, protocol);
 		break;
 	}
+	__skb_push(skb, nhpull);
 
 	return csum;
 }
-- 
2.47.1

[PATCH v13 nf-next 2/3] netfilter: bridge: Add conntrack double vlan and pppoe

[Eric Woudstra]

This adds the capability to conntrack 802.1ad, QinQ, PPPoE and PPPoE-in-Q
packets that are passing a bridge, only when a conntrack zone is set.

Signed-off-by: Eric Woudstra <ericwouds@gmail.com>
---
 net/bridge/netfilter/nf_conntrack_bridge.c | 88 ++++++++++++++++++----
 1 file changed, 72 insertions(+), 16 deletions(-)

diff --git a/net/bridge/netfilter/nf_conntrack_bridge.c b/net/bridge/netfilter/nf_conntrack_bridge.c
index 6482de4d8750..5fcb1bdf2e31 100644
--- a/net/bridge/netfilter/nf_conntrack_bridge.c
+++ b/net/bridge/netfilter/nf_conntrack_bridge.c
@@ -242,53 +242,109 @@ static unsigned int nf_ct_bridge_pre(void *priv, struct sk_buff *skb,
 {
 	struct nf_hook_state bridge_state = *state;
 	enum ip_conntrack_info ctinfo;
+	u32 len, data_len = U32_MAX;
+	int ret, offset = 0;
 	struct nf_conn *ct;
-	u32 len;
-	int ret;
+	__be16 outer_proto;
 
 	ct = nf_ct_get(skb, &ctinfo);
 	if ((ct && !nf_ct_is_template(ct)) ||
 	    ctinfo == IP_CT_UNTRACKED)
 		return NF_ACCEPT;
 
+	if (ct && nf_ct_zone_id(nf_ct_zone(ct), CTINFO2DIR(ctinfo)) !=
+			NF_CT_DEFAULT_ZONE_ID) {
+		switch (skb->protocol) {
+		case htons(ETH_P_PPP_SES): {
+			struct ppp_hdr {
+				struct pppoe_hdr hdr;
+				__be16 proto;
+			} *ph;
+
+			offset = PPPOE_SES_HLEN;
+			if (!pskb_may_pull(skb, offset))
+				return NF_ACCEPT;
+			outer_proto = skb->protocol;
+			ph = (struct ppp_hdr *)(skb->data);
+			switch (ph->proto) {
+			case htons(PPP_IP):
+				skb->protocol = htons(ETH_P_IP);
+				break;
+			case htons(PPP_IPV6):
+				skb->protocol = htons(ETH_P_IPV6);
+				break;
+			default:
+				nf_ct_set(skb, NULL, IP_CT_UNTRACKED);
+				return NF_ACCEPT;
+			}
+			data_len = ntohs(ph->hdr.length) - 2;
+			skb_set_network_header(skb, offset);
+			break;
+		}
+		case htons(ETH_P_8021Q): {
+			struct vlan_hdr *vhdr;
+
+			offset = VLAN_HLEN;
+			if (!pskb_may_pull(skb, offset))
+				return NF_ACCEPT;
+			outer_proto = skb->protocol;
+			vhdr = (struct vlan_hdr *)(skb->data);
+			skb->protocol = vhdr->h_vlan_encapsulated_proto;
+			data_len = U32_MAX;
+			skb_set_network_header(skb, offset);
+			break;
+		}
+		}
+	}
+
+	ret = NF_ACCEPT;
 	switch (skb->protocol) {
 	case htons(ETH_P_IP):
-		if (!pskb_may_pull(skb, sizeof(struct iphdr)))
-			return NF_ACCEPT;
+		if (!pskb_may_pull(skb, offset + sizeof(struct iphdr)))
+			goto do_not_track;
 
 		len = skb_ip_totlen(skb);
-		if (pskb_trim_rcsum(skb, len))
-			return NF_ACCEPT;
+		if (data_len < len)
+			len = data_len;
+		if (pskb_trim_rcsum(skb, len + offset))
+			goto do_not_track;
 
 		if (nf_ct_br_ip_check(skb))
-			return NF_ACCEPT;
+			goto do_not_track;
 
 		bridge_state.pf = NFPROTO_IPV4;
 		ret = nf_ct_br_defrag4(skb, &bridge_state);
 		break;
 	case htons(ETH_P_IPV6):
-		if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
-			return NF_ACCEPT;
+		if (!pskb_may_pull(skb, offset + sizeof(struct ipv6hdr)))
+			goto do_not_track;
 
 		len = sizeof(struct ipv6hdr) + ntohs(ipv6_hdr(skb)->payload_len);
-		if (pskb_trim_rcsum(skb, len))
-			return NF_ACCEPT;
+		if (data_len < len)
+			len = data_len;
+		if (pskb_trim_rcsum(skb, len + offset))
+			goto do_not_track;
 
 		if (nf_ct_br_ipv6_check(skb))
-			return NF_ACCEPT;
+			goto do_not_track;
 
 		bridge_state.pf = NFPROTO_IPV6;
 		ret = nf_ct_br_defrag6(skb, &bridge_state);
 		break;
 	default:
 		nf_ct_set(skb, NULL, IP_CT_UNTRACKED);
-		return NF_ACCEPT;
+		goto do_not_track;
 	}
 
-	if (ret != NF_ACCEPT)
-		return ret;
+	if (ret == NF_ACCEPT)
+		ret = nf_conntrack_in(skb, &bridge_state);
 
-	return nf_conntrack_in(skb, &bridge_state);
+do_not_track:
+	if (offset) {
+		skb_reset_network_header(skb);
+		skb->protocol = outer_proto;
+	}
+	return ret;
 }
 
 static unsigned int nf_ct_bridge_in(void *priv, struct sk_buff *skb,
-- 
2.47.1

[PATCH v13 nf-next 3/3] netfilter: nft_chain_filter: Add bridge double vlan and pppoe

[Eric Woudstra]

This adds the capability to evaluate 802.1ad, QinQ, PPPoE and PPPoE-in-Q
packets in the bridge filter chain.

Signed-off-by: Eric Woudstra <ericwouds@gmail.com>
---
 net/netfilter/nft_chain_filter.c | 52 +++++++++++++++++++++++++++++++-
 1 file changed, 51 insertions(+), 1 deletion(-)

diff --git a/net/netfilter/nft_chain_filter.c b/net/netfilter/nft_chain_filter.c
index 19a553550c76..8445ddfb9cea 100644
--- a/net/netfilter/nft_chain_filter.c
+++ b/net/netfilter/nft_chain_filter.c
@@ -232,11 +232,55 @@ nft_do_chain_bridge(void *priv,
 		    struct sk_buff *skb,
 		    const struct nf_hook_state *state)
 {
+	__be16 outer_proto, proto = 0;
 	struct nft_pktinfo pkt;
+	int ret, offset = 0;
 
 	nft_set_pktinfo(&pkt, skb, state);
 
 	switch (eth_hdr(skb)->h_proto) {
+	case htons(ETH_P_PPP_SES): {
+		struct ppp_hdr {
+			struct pppoe_hdr hdr;
+			__be16 proto;
+		} *ph;
+
+		if (!pskb_may_pull(skb, PPPOE_SES_HLEN))
+			break;
+		offset = PPPOE_SES_HLEN;
+		outer_proto = skb->protocol;
+		ph = (struct ppp_hdr *)(skb->data);
+		switch (ph->proto) {
+		case htons(PPP_IP):
+			proto = htons(ETH_P_IP);
+			break;
+		case htons(PPP_IPV6):
+			proto = htons(ETH_P_IPV6);
+			break;
+		}
+		skb_set_network_header(skb, offset);
+		skb->protocol = proto;
+		break;
+	}
+	case htons(ETH_P_8021Q): {
+		struct vlan_hdr *vhdr;
+
+		if (!pskb_may_pull(skb, VLAN_HLEN))
+			break;
+		offset = VLAN_HLEN;
+		outer_proto = skb->protocol;
+		vhdr = (struct vlan_hdr *)(skb->data);
+		proto = vhdr->h_vlan_encapsulated_proto;
+		skb_set_network_header(skb, offset);
+		skb->protocol = proto;
+		break;
+	}
+	default:
+		proto = eth_hdr(skb)->h_proto;
+		break;
+	}
+
+	switch (proto) {
 	case htons(ETH_P_IP):
 		nft_set_pktinfo_ipv4_validate(&pkt);
 		break;
@@ -248,7 +292,13 @@ nft_do_chain_bridge(void *priv,
 		break;
 	}
 
-	return nft_do_chain(&pkt, priv);
+	ret = nft_do_chain(&pkt, priv);
+
+	if (offset) {
+		skb_reset_network_header(skb);
+		skb->protocol = outer_proto;
+	}
+	return ret;
 }
 
 static const struct nft_chain_type nft_chain_filter_bridge = {
-- 
2.47.1

Re: [PATCH v13 nf-next 1/3] netfilter: utils: nf_checksum(_partial) correct data!=networkheader

[Florian Westphal]

Eric Woudstra <ericwouds@gmail.com> wrote:
> In the conntrack hook it may not always be the case that:
> skb_network_header(skb) == skb->data.
> 
> This is problematic when L4 function nf_conntrack_handle_packet()
> is accessing L3 data. This function uses thoff and ip_hdr()
> to finds it's data. But it also calculates the checksum.
> nf_checksum() and nf_checksum_partial() both use lower skb-checksum
> functions that are based on using skb->data.
> 
> When skb_network_header(skb) != skb->data, adjust accordingly,
> so that the checksum is calculated correctly.
> 
> Signed-off-by: Eric Woudstra <ericwouds@gmail.com>
> ---
>  net/netfilter/utils.c | 22 ++++++++++++++++------
>  1 file changed, 16 insertions(+), 6 deletions(-)
> 
> diff --git a/net/netfilter/utils.c b/net/netfilter/utils.c
> index 008419db815a..daee035c25b8 100644
> --- a/net/netfilter/utils.c
> +++ b/net/netfilter/utils.c
> @@ -124,16 +124,21 @@ __sum16 nf_checksum(struct sk_buff *skb, unsigned int hook,
>  		    unsigned int dataoff, u8 protocol,
>  		    unsigned short family)
>  {
> +	unsigned int nhpull = skb_network_header(skb) - skb->data;
>  	__sum16 csum = 0;
>  
> +	if (!pskb_may_pull(skb, nhpull))
> +		return -ENOMEM;

Hmm.  Not sure about this.  We should really audit all conntrack users
to make sure the network header is in the linear area, i.e.
ip_hdr() and friends return the right value, even though skb->data !=
skb_network_header().

Such may_pull, in case of skb->head reallocation, invalidate a pointer
to e.g. ethernet header in the caller.

No idea if we have callers that do this, I did not check, but such
"hidden" pulls tend to cause hard to spot bugs.

Maybe use
       if (WARN_ON_ONCE(skb_pointer_if_linear())
		return 0;

instead?  That allows to track down any offenders.  Given conntrack
takes presence of the l3 header in the linear area for granted, I don't
see how this can ever trigger.  You could also use
DEBUG_NET_WARN_ON_ONCE if you prefer, given this condition should never
be true anyway.

Re: [PATCH v13 nf-next 3/3] netfilter: nft_chain_filter: Add bridge double vlan and pppoe

[Florian Westphal]

Eric Woudstra <ericwouds@gmail.com> wrote:
> This adds the capability to evaluate 802.1ad, QinQ, PPPoE and PPPoE-in-Q
> packets in the bridge filter chain.
> 
> Signed-off-by: Eric Woudstra <ericwouds@gmail.com>
> ---
>  net/netfilter/nft_chain_filter.c | 52 +++++++++++++++++++++++++++++++-
>  1 file changed, 51 insertions(+), 1 deletion(-)
> 
> diff --git a/net/netfilter/nft_chain_filter.c b/net/netfilter/nft_chain_filter.c
> index 19a553550c76..8445ddfb9cea 100644
> --- a/net/netfilter/nft_chain_filter.c
> +++ b/net/netfilter/nft_chain_filter.c
> @@ -232,11 +232,55 @@ nft_do_chain_bridge(void *priv,
>  		    struct sk_buff *skb,
>  		    const struct nf_hook_state *state)
>  {
> +	__be16 outer_proto, proto = 0;
>  	struct nft_pktinfo pkt;
> +	int ret, offset = 0;
>  
>  	nft_set_pktinfo(&pkt, skb, state);
>  
>  	switch (eth_hdr(skb)->h_proto) {
> +	case htons(ETH_P_PPP_SES): {
> +		struct ppp_hdr {
> +			struct pppoe_hdr hdr;
> +			__be16 proto;
> +		} *ph;
> +
> +		if (!pskb_may_pull(skb, PPPOE_SES_HLEN))
> +			break;
> +		offset = PPPOE_SES_HLEN;
> +		outer_proto = skb->protocol;
> +		ph = (struct ppp_hdr *)(skb->data);
> +		switch (ph->proto) {
> +		case htons(PPP_IP):
> +			proto = htons(ETH_P_IP);
> +			break;
> +		case htons(PPP_IPV6):
> +			proto = htons(ETH_P_IPV6);
> +			break;
> +		}

What if ph->proto is neither ipv4 nor ipv6?  I don't think
we should clobber skb->protocol or set a new network header in that
case.

> +      ret = nft_do_chain(&pkt, priv);
> +
> +      if (offset) {
> +               skb_reset_network_header(skb);

if ret == NF_STOLEN, skb has already been free'd or is queued
elsewhere and must not be modified anymore.

I would restrict this to ret == NF_ACCEPT.

Re: [PATCH v13 nf-next 1/3] netfilter: utils: nf_checksum(_partial) correct data!=networkheader

[kernel test robot]

Hi Eric,

kernel test robot noticed the following build warnings:

[auto build test WARNING on netfilter-nf/main]
[also build test WARNING on horms-ipvs/master linus/master v6.16-rc4 next-20250704]
[cannot apply to nf-next/master]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Eric-Woudstra/netfilter-utils-nf_checksum-_partial-correct-data-networkheader/20250705-031418
base:   https://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf.git main
patch link:    https://lore.kernel.org/r/20250704191135.1815969-2-ericwouds%40gmail.com
patch subject: [PATCH v13 nf-next 1/3] netfilter: utils: nf_checksum(_partial) correct data!=networkheader
config: x86_64-randconfig-121-20250705 (https://download.01.org/0day-ci/archive/20250706/202507060106.A5xgr1Rs-lkp@intel.com/config)
compiler: clang version 20.1.7 (https://github.com/llvm/llvm-project 6146a88f60492b520a36f8f8f3231e15f3cc6082)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250706/202507060106.A5xgr1Rs-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202507060106.A5xgr1Rs-lkp@intel.com/

sparse warnings: (new ones prefixed by >>)
>> net/netfilter/utils.c:131:24: sparse: sparse: incorrect type in return expression (different base types) @@     expected restricted __sum16 @@     got int @@
   net/netfilter/utils.c:131:24: sparse:     expected restricted __sum16
   net/netfilter/utils.c:131:24: sparse:     got int
   net/netfilter/utils.c:155:24: sparse: sparse: incorrect type in return expression (different base types) @@     expected restricted __sum16 @@     got int @@
   net/netfilter/utils.c:155:24: sparse:     expected restricted __sum16
   net/netfilter/utils.c:155:24: sparse:     got int

vim +131 net/netfilter/utils.c

   122	
   123	__sum16 nf_checksum(struct sk_buff *skb, unsigned int hook,
   124			    unsigned int dataoff, u8 protocol,
   125			    unsigned short family)
   126	{
   127		unsigned int nhpull = skb_network_header(skb) - skb->data;
   128		__sum16 csum = 0;
   129	
   130		if (!pskb_may_pull(skb, nhpull))
 > 131			return -ENOMEM;
   132		__skb_pull(skb, nhpull);
   133		switch (family) {
   134		case AF_INET:
   135			csum = nf_ip_checksum(skb, hook, dataoff - nhpull, protocol);
   136			break;
   137		case AF_INET6:
   138			csum = nf_ip6_checksum(skb, hook, dataoff - nhpull, protocol);
   139			break;
   140		}
   141		__skb_push(skb, nhpull);
   142	
   143		return csum;
   144	}
   145	EXPORT_SYMBOL_GPL(nf_checksum);
   146	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

Re: [PATCH v13 nf-next 1/3] netfilter: utils: nf_checksum(_partial) correct data!=networkheader

[kernel test robot]

BCC: lkp@intel.com
CC: oe-kbuild-all@lists.linux.dev
In-Reply-To: <20250704191135.1815969-2-ericwouds@gmail.com>
References: <20250704191135.1815969-2-ericwouds@gmail.com>
TO: Eric Woudstra <ericwouds@gmail.com>
TO: Pablo Neira Ayuso <pablo@netfilter.org>
TO: Jozsef Kadlecsik <kadlec@netfilter.org>
TO: Nikolay Aleksandrov <razor@blackwall.org>
TO: Ido Schimmel <idosch@nvidia.com>
TO: "David S. Miller" <davem@davemloft.net>
CC: netdev@vger.kernel.org
TO: Eric Dumazet <edumazet@google.com>
TO: Jakub Kicinski <kuba@kernel.org>
TO: Paolo Abeni <pabeni@redhat.com>
TO: Simon Horman <horms@kernel.org>
CC: netfilter-devel@vger.kernel.org
CC: bridge@lists.linux.dev
CC: Eric Woudstra <ericwouds@gmail.com>

Hi Eric,

kernel test robot noticed the following build warnings:

[auto build test WARNING on netfilter-nf/main]
[also build test WARNING on horms-ipvs/master linus/master v6.16-rc4 next-20250704]
[cannot apply to nf-next/master]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Eric-Woudstra/netfilter-utils-nf_checksum-_partial-correct-data-networkheader/20250705-031418
base:   https://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf.git main
patch link:    https://lore.kernel.org/r/20250704191135.1815969-2-ericwouds%40gmail.com
patch subject: [PATCH v13 nf-next 1/3] netfilter: utils: nf_checksum(_partial) correct data!=networkheader
:::::: branch date: 2 days ago
:::::: commit date: 2 days ago
config: x86_64-randconfig-r071-20250706 (https://download.01.org/0day-ci/archive/20250706/202507061710.RCwA4Kjw-lkp@intel.com/config)
compiler: gcc-12 (Debian 12.2.0-14+deb12u1) 12.2.0

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Reported-by: Dan Carpenter <error27@gmail.com>
| Closes: https://lore.kernel.org/r/202507061710.RCwA4Kjw-lkp@intel.com/

smatch warnings:
net/netfilter/utils.c:131 nf_checksum() warn: signedness bug returning '(-12)'
net/netfilter/utils.c:155 nf_checksum_partial() warn: signedness bug returning '(-12)'

vim +131 net/netfilter/utils.c

ebee5a50d0b7cd Florian Westphal  2018-06-25  122  
ef71fe27ec2f16 Pablo Neira Ayuso 2017-11-27  123  __sum16 nf_checksum(struct sk_buff *skb, unsigned int hook,
ebee5a50d0b7cd Florian Westphal  2018-06-25  124  		    unsigned int dataoff, u8 protocol,
ef71fe27ec2f16 Pablo Neira Ayuso 2017-11-27  125  		    unsigned short family)
ef71fe27ec2f16 Pablo Neira Ayuso 2017-11-27  126  {
39644744ee13d9 Eric Woudstra     2025-07-04  127  	unsigned int nhpull = skb_network_header(skb) - skb->data;
ef71fe27ec2f16 Pablo Neira Ayuso 2017-11-27  128  	__sum16 csum = 0;
ef71fe27ec2f16 Pablo Neira Ayuso 2017-11-27  129  
39644744ee13d9 Eric Woudstra     2025-07-04  130  	if (!pskb_may_pull(skb, nhpull))
39644744ee13d9 Eric Woudstra     2025-07-04 @131  		return -ENOMEM;
39644744ee13d9 Eric Woudstra     2025-07-04  132  	__skb_pull(skb, nhpull);
ef71fe27ec2f16 Pablo Neira Ayuso 2017-11-27  133  	switch (family) {
ef71fe27ec2f16 Pablo Neira Ayuso 2017-11-27  134  	case AF_INET:
39644744ee13d9 Eric Woudstra     2025-07-04  135  		csum = nf_ip_checksum(skb, hook, dataoff - nhpull, protocol);
ef71fe27ec2f16 Pablo Neira Ayuso 2017-11-27  136  		break;
ef71fe27ec2f16 Pablo Neira Ayuso 2017-11-27  137  	case AF_INET6:
39644744ee13d9 Eric Woudstra     2025-07-04  138  		csum = nf_ip6_checksum(skb, hook, dataoff - nhpull, protocol);
ef71fe27ec2f16 Pablo Neira Ayuso 2017-11-27  139  		break;
ef71fe27ec2f16 Pablo Neira Ayuso 2017-11-27  140  	}
39644744ee13d9 Eric Woudstra     2025-07-04  141  	__skb_push(skb, nhpull);
ef71fe27ec2f16 Pablo Neira Ayuso 2017-11-27  142  
ef71fe27ec2f16 Pablo Neira Ayuso 2017-11-27  143  	return csum;
ef71fe27ec2f16 Pablo Neira Ayuso 2017-11-27  144  }
ef71fe27ec2f16 Pablo Neira Ayuso 2017-11-27  145  EXPORT_SYMBOL_GPL(nf_checksum);
f7dcbe2f36a660 Pablo Neira Ayuso 2017-12-20  146  
f7dcbe2f36a660 Pablo Neira Ayuso 2017-12-20  147  __sum16 nf_checksum_partial(struct sk_buff *skb, unsigned int hook,
f7dcbe2f36a660 Pablo Neira Ayuso 2017-12-20  148  			    unsigned int dataoff, unsigned int len,
ebee5a50d0b7cd Florian Westphal  2018-06-25  149  			    u8 protocol, unsigned short family)
f7dcbe2f36a660 Pablo Neira Ayuso 2017-12-20  150  {
39644744ee13d9 Eric Woudstra     2025-07-04  151  	unsigned int nhpull = skb_network_header(skb) - skb->data;
f7dcbe2f36a660 Pablo Neira Ayuso 2017-12-20  152  	__sum16 csum = 0;
f7dcbe2f36a660 Pablo Neira Ayuso 2017-12-20  153  
39644744ee13d9 Eric Woudstra     2025-07-04  154  	if (!pskb_may_pull(skb, nhpull))
39644744ee13d9 Eric Woudstra     2025-07-04 @155  		return -ENOMEM;
39644744ee13d9 Eric Woudstra     2025-07-04  156  	__skb_pull(skb, nhpull);
f7dcbe2f36a660 Pablo Neira Ayuso 2017-12-20  157  	switch (family) {
f7dcbe2f36a660 Pablo Neira Ayuso 2017-12-20  158  	case AF_INET:
39644744ee13d9 Eric Woudstra     2025-07-04  159  		csum = nf_ip_checksum_partial(skb, hook, dataoff - nhpull,
39644744ee13d9 Eric Woudstra     2025-07-04  160  					      len, protocol);
f7dcbe2f36a660 Pablo Neira Ayuso 2017-12-20  161  		break;
f7dcbe2f36a660 Pablo Neira Ayuso 2017-12-20  162  	case AF_INET6:
39644744ee13d9 Eric Woudstra     2025-07-04  163  		csum = nf_ip6_checksum_partial(skb, hook, dataoff - nhpull,
39644744ee13d9 Eric Woudstra     2025-07-04  164  					       len, protocol);
f7dcbe2f36a660 Pablo Neira Ayuso 2017-12-20  165  		break;
f7dcbe2f36a660 Pablo Neira Ayuso 2017-12-20  166  	}
39644744ee13d9 Eric Woudstra     2025-07-04  167  	__skb_push(skb, nhpull);
f7dcbe2f36a660 Pablo Neira Ayuso 2017-12-20  168  
f7dcbe2f36a660 Pablo Neira Ayuso 2017-12-20  169  	return csum;
f7dcbe2f36a660 Pablo Neira Ayuso 2017-12-20  170  }
f7dcbe2f36a660 Pablo Neira Ayuso 2017-12-20  171  EXPORT_SYMBOL_GPL(nf_checksum_partial);
3f87c08c615f56 Pablo Neira Ayuso 2017-11-27  172  

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Re: [PATCH v13 nf-next 1/3] netfilter: utils: nf_checksum(_partial) correct data!=networkheader

[Dan Carpenter]

Hi Eric,

kernel test robot noticed the following build warnings:

https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Eric-Woudstra/netfilter-utils-nf_checksum-_partial-correct-data-networkheader/20250705-031418
base:   https://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf.git main
patch link:    https://lore.kernel.org/r/20250704191135.1815969-2-ericwouds%40gmail.com
patch subject: [PATCH v13 nf-next 1/3] netfilter: utils: nf_checksum(_partial) correct data!=networkheader
config: x86_64-randconfig-r071-20250706 (https://download.01.org/0day-ci/archive/20250706/202507061710.RCwA4Kjw-lkp@intel.com/config)
compiler: gcc-12 (Debian 12.2.0-14+deb12u1) 12.2.0

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
| Closes: https://lore.kernel.org/r/202507061710.RCwA4Kjw-lkp@intel.com/

smatch warnings:
net/netfilter/utils.c:131 nf_checksum() warn: signedness bug returning '(-12)'
net/netfilter/utils.c:155 nf_checksum_partial() warn: signedness bug returning '(-12)'

vim +131 net/netfilter/utils.c

ef71fe27ec2f16 Pablo Neira Ayuso 2017-11-27  123  __sum16 nf_checksum(struct sk_buff *skb, unsigned int hook,
                                                  ^^^^^^^
ebee5a50d0b7cd Florian Westphal  2018-06-25  124  		    unsigned int dataoff, u8 protocol,
ef71fe27ec2f16 Pablo Neira Ayuso 2017-11-27  125  		    unsigned short family)
ef71fe27ec2f16 Pablo Neira Ayuso 2017-11-27  126  {
39644744ee13d9 Eric Woudstra     2025-07-04  127  	unsigned int nhpull = skb_network_header(skb) - skb->data;
ef71fe27ec2f16 Pablo Neira Ayuso 2017-11-27  128  	__sum16 csum = 0;
ef71fe27ec2f16 Pablo Neira Ayuso 2017-11-27  129  
39644744ee13d9 Eric Woudstra     2025-07-04  130  	if (!pskb_may_pull(skb, nhpull))
39644744ee13d9 Eric Woudstra     2025-07-04 @131  		return -ENOMEM;

This -ENOMEM doesn't work because the return type is u16.

39644744ee13d9 Eric Woudstra     2025-07-04  132  	__skb_pull(skb, nhpull);
ef71fe27ec2f16 Pablo Neira Ayuso 2017-11-27  133  	switch (family) {
ef71fe27ec2f16 Pablo Neira Ayuso 2017-11-27  134  	case AF_INET:
39644744ee13d9 Eric Woudstra     2025-07-04  135  		csum = nf_ip_checksum(skb, hook, dataoff - nhpull, protocol);
ef71fe27ec2f16 Pablo Neira Ayuso 2017-11-27  136  		break;
ef71fe27ec2f16 Pablo Neira Ayuso 2017-11-27  137  	case AF_INET6:
39644744ee13d9 Eric Woudstra     2025-07-04  138  		csum = nf_ip6_checksum(skb, hook, dataoff - nhpull, protocol);
ef71fe27ec2f16 Pablo Neira Ayuso 2017-11-27  139  		break;
ef71fe27ec2f16 Pablo Neira Ayuso 2017-11-27  140  	}
39644744ee13d9 Eric Woudstra     2025-07-04  141  	__skb_push(skb, nhpull);
ef71fe27ec2f16 Pablo Neira Ayuso 2017-11-27  142  
ef71fe27ec2f16 Pablo Neira Ayuso 2017-11-27  143  	return csum;
ef71fe27ec2f16 Pablo Neira Ayuso 2017-11-27  144  }
ef71fe27ec2f16 Pablo Neira Ayuso 2017-11-27  145  EXPORT_SYMBOL_GPL(nf_checksum);
f7dcbe2f36a660 Pablo Neira Ayuso 2017-12-20  146  
f7dcbe2f36a660 Pablo Neira Ayuso 2017-12-20  147  __sum16 nf_checksum_partial(struct sk_buff *skb, unsigned int hook,
f7dcbe2f36a660 Pablo Neira Ayuso 2017-12-20  148  			    unsigned int dataoff, unsigned int len,
ebee5a50d0b7cd Florian Westphal  2018-06-25  149  			    u8 protocol, unsigned short family)
f7dcbe2f36a660 Pablo Neira Ayuso 2017-12-20  150  {
39644744ee13d9 Eric Woudstra     2025-07-04  151  	unsigned int nhpull = skb_network_header(skb) - skb->data;
f7dcbe2f36a660 Pablo Neira Ayuso 2017-12-20  152  	__sum16 csum = 0;
f7dcbe2f36a660 Pablo Neira Ayuso 2017-12-20  153  
39644744ee13d9 Eric Woudstra     2025-07-04  154  	if (!pskb_may_pull(skb, nhpull))
39644744ee13d9 Eric Woudstra     2025-07-04 @155  		return -ENOMEM;

Same.

39644744ee13d9 Eric Woudstra     2025-07-04  156  	__skb_pull(skb, nhpull);
f7dcbe2f36a660 Pablo Neira Ayuso 2017-12-20  157  	switch (family) {
f7dcbe2f36a660 Pablo Neira Ayuso 2017-12-20  158  	case AF_INET:
39644744ee13d9 Eric Woudstra     2025-07-04  159  		csum = nf_ip_checksum_partial(skb, hook, dataoff - nhpull,
39644744ee13d9 Eric Woudstra     2025-07-04  160  					      len, protocol);
f7dcbe2f36a660 Pablo Neira Ayuso 2017-12-20  161  		break;
f7dcbe2f36a660 Pablo Neira Ayuso 2017-12-20  162  	case AF_INET6:
39644744ee13d9 Eric Woudstra     2025-07-04  163  		csum = nf_ip6_checksum_partial(skb, hook, dataoff - nhpull,
39644744ee13d9 Eric Woudstra     2025-07-04  164  					       len, protocol);
f7dcbe2f36a660 Pablo Neira Ayuso 2017-12-20  165  		break;
f7dcbe2f36a660 Pablo Neira Ayuso 2017-12-20  166  	}
39644744ee13d9 Eric Woudstra     2025-07-04  167  	__skb_push(skb, nhpull);
f7dcbe2f36a660 Pablo Neira Ayuso 2017-12-20  168  
f7dcbe2f36a660 Pablo Neira Ayuso 2017-12-20  169  	return csum;
f7dcbe2f36a660 Pablo Neira Ayuso 2017-12-20  170  }

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