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Date: Mon, 10 May 2021 08:41:14 -0700
From: Alexander Duyck <alexander.duyck@...il.com>
To: Michael Chan <michael.chan@...adcom.com>
Cc: David Miller <davem@...emloft.net>,
Netdev <netdev@...r.kernel.org>,
Jakub Kicinski <kuba@...nel.org>,
Andy Gospodarek <gospo@...adcom.com>
Subject: Re: [PATCH net v2] bnxt_en: Fix and improve .ndo_features_check().
On Fri, May 7, 2021 at 5:29 PM Michael Chan <michael.chan@...adcom.com> wrote:
>
> Jakub Kicinski pointed out that we need to handle ipv6 extension headers
> and to explicitly check for supported tunnel types in
> .ndo_features_check().
>
> For ipv6 extension headers, the hardware supports up to 2 ext. headers
> and each must be <= 64 bytes. For tunneled packets, the supported
> packets are UDP with supported VXLAN and Geneve ports, GRE, and IPIP.
>
> v2: Add missing step to check inner ipv6 header for UDP and GRE tunnels.
> Check TCP/UDP next header after skipping ipv6 ext headers for
> non-tunneled packets and for inner ipv6.
> (Both feedback from Alexander Duyck)
>
> Reviewed-by: Edwin Peer <edwin.peer@...adcom.com>
> Reviewed-by: Pavan Chebbi <pavan.chebbi@...adcom.com>
> Fixes: 1698d600b361 ("bnxt_en: Implement .ndo_features_check().")
> Signed-off-by: Michael Chan <michael.chan@...adcom.com>
> ---
> drivers/net/ethernet/broadcom/bnxt/bnxt.c | 125 +++++++++++++++++++---
> 1 file changed, 108 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
> index 39ac9e2f5118..8e4670e37140 100644
> --- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
> +++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
> @@ -10785,37 +10785,128 @@ static int bnxt_set_features(struct net_device *dev, netdev_features_t features)
> return rc;
> }
>
> +static bool bnxt_exthdr_check(struct bnxt *bp, struct sk_buff *skb, int nw_off,
> + u8 *nextproto)
> +{
> + struct ipv6hdr *ip6h = (struct ipv6hdr *)(skb->data + nw_off);
> + int hdr_count = 0;
> + u8 nexthdr;
> + int start;
> +
> + /* Check that there are at most 2 IPv6 extension headers, no
> + * fragment header, and each is <= 64 bytes.
> + */
> + start = nw_off + sizeof(*ip6h);
> + nexthdr = ip6h->nexthdr;
> + while (ipv6_ext_hdr(nexthdr)) {
> + struct ipv6_opt_hdr _hdr, *hp;
> + int hdrlen;
> +
> + if (hdr_count >= 3 || nexthdr == NEXTHDR_NONE ||
> + nexthdr == NEXTHDR_FRAGMENT)
> + return false;
> + hp = skb_header_pointer(skb, start, sizeof(_hdr), &_hdr);
> + if (!hp)
> + return false;
> + if (nexthdr == NEXTHDR_AUTH)
> + hdrlen = ipv6_authlen(hp);
> + else
> + hdrlen = ipv6_optlen(hp);
> +
> + if (hdrlen > 64)
> + return false;
> + nexthdr = hp->nexthdr;
> + start += hdrlen;
> + hdr_count++;
> + }
> + /* Only support TCP/UDP unless the caller checks the nextproto. */
> + if (nextproto) {
> + *nextproto = nexthdr;
> + return true;
> + }
> + if (nexthdr == IPPROTO_TCP || nexthdr == IPPROTO_UDP)
> + return true;
> + return false;
> +}
> +
> +/* For UDP, we can only handle 1 Vxlan port and 1 Geneve port. */
> +static bool bnxt_udp_tunl_check(struct bnxt *bp, struct sk_buff *skb)
> +{
> + struct udphdr *uh = udp_hdr(skb);
> + __be16 udp_port = uh->dest;
> +
> + if (udp_port != bp->vxlan_port && udp_port != bp->nge_port)
> + return false;
> + if (skb->inner_protocol_type == ENCAP_TYPE_ETHER) {
> + struct ethhdr *eh = inner_eth_hdr(skb);
> +
> + switch (eh->h_proto) {
> + case htons(ETH_P_IP):
> + return true;
> + case htons(ETH_P_IPV6):
> + return bnxt_exthdr_check(bp, skb,
> + skb_inner_network_offset(skb),
> + NULL);
> + }
> + }
> + return false;
> +}
> +
> +static bool bnxt_tunl_check(struct bnxt *bp, struct sk_buff *skb, u8 l4_proto)
> +{
> + switch (l4_proto) {
> + case IPPROTO_UDP:
> + return bnxt_udp_tunl_check(bp, skb);
> + case IPPROTO_IPIP:
> + return true;
> + case IPPROTO_GRE: {
> + switch (skb->inner_protocol) {
> + default:
> + return false;
> + case htons(ETH_P_IP):
> + return true;
> + case htons(ETH_P_IPV6):
> + fallthrough;
> + }
> + }
> + case IPPROTO_IPV6:
> + /* Check ext headers of inner ipv6 */
> + return bnxt_exthdr_check(bp, skb, skb_inner_network_offset(skb),
> + NULL);
> + }
> + return false;
> +}
> +
> static netdev_features_t bnxt_features_check(struct sk_buff *skb,
> struct net_device *dev,
> netdev_features_t features)
> {
> - struct bnxt *bp;
> - __be16 udp_port;
> + struct bnxt *bp = netdev_priv(dev);
> u8 l4_proto = 0;
>
> features = vlan_features_check(skb, features);
> - if (!skb->encapsulation)
> - return features;
> -
> switch (vlan_get_protocol(skb)) {
> case htons(ETH_P_IP):
> + if (!skb->encapsulation)
> + return features;
> l4_proto = ip_hdr(skb)->protocol;
> - break;
> + if (!bnxt_tunl_check(bp, skb, l4_proto))
> + goto disable_offload;
What is the point of this label, couldn't you just use a break since
this is in a switch statement? Or you could flip the logic and have it
return features if you successfully determined the offload is doable
and then default to adding a break at the end of the case section.
> + return features;
> case htons(ETH_P_IPV6):
> - l4_proto = ipv6_hdr(skb)->nexthdr;
> + if (!bnxt_exthdr_check(bp, skb, skb_network_offset(skb),
> + &l4_proto))
> + goto disable_offload;
Same here. You could probably just use a break statement.
Also you might save yourself a step here by passing an actual pointer
instead of the address of l4_proto here. Then what you could do is in
the skb->encapsulation case you initialize the pointer to the address
of l4_proto, and in the non encap case you set the pointer to NULL.
Doing that you can avoid having to repeat the same TCP/UDP check below
and could instead just return features if !pointer ||
bnxt_tunl_check().
> + if (skb->encapsulation) {
> + if (bnxt_tunl_check(bp, skb, l4_proto))
> + return features;
> + } else if (l4_proto == IPPROTO_TCP || l4_proto == IPPROTO_UDP) {
> + return features;
> + }
> break;
> - default:
> - return features;
> }
>
> - if (l4_proto != IPPROTO_UDP)
> - return features;
> -
> - bp = netdev_priv(dev);
> - /* For UDP, we can only handle 1 Vxlan port and 1 Geneve port. */
> - udp_port = udp_hdr(skb)->dest;
> - if (udp_port == bp->vxlan_port || udp_port == bp->nge_port)
> - return features;
> +disable_offload:
> return features & ~(NETIF_F_CSUM_MASK | NETIF_F_GSO_MASK);
> }
>
> --
> 2.18.1
>
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