On Thu, Mar 01, 2018 at 05:13:37PM +1100, Daniel Axtens wrote:
> If you take a GSO skb, and split it into packets, will the network
> length (L3 headers + L4 headers + payload) of those packets be small
> enough to fit within a given MTU?
>
> skb_gso_validate_mtu gives you the answer to that question. However,
> we recently added to add a way to validate the MAC length of a split GSO
> skb (L2+L3+L4+payload), and the names get confusing, so rename
> skb_gso_validate_mtu to skb_gso_validate_network_len
>
> Signed-off-by: Daniel Axtens <d...@axtens.net>
Reviewed-by: Marcelo Ricardo Leitner <marcelo.leit...@gmail.com>
> ---
> include/linux/skbuff.h | 2 +-
> net/core/skbuff.c | 11 ++++++-----
> net/ipv4/ip_forward.c | 2 +-
> net/ipv4/ip_output.c | 2 +-
> net/ipv4/netfilter/nf_flow_table_ipv4.c | 2 +-
> net/ipv6/ip6_output.c | 2 +-
> net/ipv6/netfilter/nf_flow_table_ipv6.c | 2 +-
> net/mpls/af_mpls.c | 2 +-
> net/xfrm/xfrm_device.c | 2 +-
> 9 files changed, 14 insertions(+), 13 deletions(-)
>
> diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
> index c1e66bdcf583..a057dd1a75c7 100644
> --- a/include/linux/skbuff.h
> +++ b/include/linux/skbuff.h
> @@ -3286,7 +3286,7 @@ void skb_split(struct sk_buff *skb, struct sk_buff
> *skb1, const u32 len);
> int skb_shift(struct sk_buff *tgt, struct sk_buff *skb, int shiftlen);
> void skb_scrub_packet(struct sk_buff *skb, bool xnet);
> unsigned int skb_gso_transport_seglen(const struct sk_buff *skb);
> -bool skb_gso_validate_mtu(const struct sk_buff *skb, unsigned int mtu);
> +bool skb_gso_validate_network_len(const struct sk_buff *skb, unsigned int
> mtu);
> bool skb_gso_validate_mac_len(const struct sk_buff *skb, unsigned int len);
> struct sk_buff *skb_segment(struct sk_buff *skb, netdev_features_t features);
> struct sk_buff *skb_vlan_untag(struct sk_buff *skb);
> diff --git a/net/core/skbuff.c b/net/core/skbuff.c
> index 09bd89c90a71..b63767008824 100644
> --- a/net/core/skbuff.c
> +++ b/net/core/skbuff.c
> @@ -4955,19 +4955,20 @@ static inline bool skb_gso_size_check(const struct
> sk_buff *skb,
> }
>
> /**
> - * skb_gso_validate_mtu - Return in case such skb fits a given MTU
> + * skb_gso_validate_network_len - Will a split GSO skb fit into a given MTU?
> *
> * @skb: GSO skb
> * @mtu: MTU to validate against
> *
> - * skb_gso_validate_mtu validates if a given skb will fit a wanted MTU
> - * once split.
> + * skb_gso_validate_network_len validates if a given skb will fit a
> + * wanted MTU once split. It considers L3 headers, L4 headers, and the
> + * payload.
> */
> -bool skb_gso_validate_mtu(const struct sk_buff *skb, unsigned int mtu)
> +bool skb_gso_validate_network_len(const struct sk_buff *skb, unsigned int
> mtu)
> {
> return skb_gso_size_check(skb, skb_gso_network_seglen(skb), mtu);
> }
> -EXPORT_SYMBOL_GPL(skb_gso_validate_mtu);
> +EXPORT_SYMBOL_GPL(skb_gso_validate_network_len);
>
> /**
> * skb_gso_validate_mac_len - Will a split GSO skb fit in a given length?
> diff --git a/net/ipv4/ip_forward.c b/net/ipv4/ip_forward.c
> index 2dd21c3281a1..b54b948b0596 100644
> --- a/net/ipv4/ip_forward.c
> +++ b/net/ipv4/ip_forward.c
> @@ -55,7 +55,7 @@ static bool ip_exceeds_mtu(const struct sk_buff *skb,
> unsigned int mtu)
> if (skb->ignore_df)
> return false;
>
> - if (skb_is_gso(skb) && skb_gso_validate_mtu(skb, mtu))
> + if (skb_is_gso(skb) && skb_gso_validate_network_len(skb, mtu))
> return false;
>
> return true;
> diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
> index e8e675be60ec..66340ab750e6 100644
> --- a/net/ipv4/ip_output.c
> +++ b/net/ipv4/ip_output.c
> @@ -248,7 +248,7 @@ static int ip_finish_output_gso(struct net *net, struct
> sock *sk,
>
> /* common case: seglen is <= mtu
> */
> - if (skb_gso_validate_mtu(skb, mtu))
> + if (skb_gso_validate_network_len(skb, mtu))
> return ip_finish_output2(net, sk, skb);
>
> /* Slowpath - GSO segment length exceeds the egress MTU.
> diff --git a/net/ipv4/netfilter/nf_flow_table_ipv4.c
> b/net/ipv4/netfilter/nf_flow_table_ipv4.c
> index 25d2975da156..2447077d163d 100644
> --- a/net/ipv4/netfilter/nf_flow_table_ipv4.c
> +++ b/net/ipv4/netfilter/nf_flow_table_ipv4.c
> @@ -185,7 +185,7 @@ static bool __nf_flow_exceeds_mtu(const struct sk_buff
> *skb, unsigned int mtu)
> if ((ip_hdr(skb)->frag_off & htons(IP_DF)) == 0)
> return false;
>
> - if (skb_is_gso(skb) && skb_gso_validate_mtu(skb, mtu))
> + if (skb_is_gso(skb) && skb_gso_validate_network_len(skb, mtu))
> return false;
>
> return true;
> diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
> index 997c7f19ad62..a8a919520090 100644
> --- a/net/ipv6/ip6_output.c
> +++ b/net/ipv6/ip6_output.c
> @@ -412,7 +412,7 @@ static bool ip6_pkt_too_big(const struct sk_buff *skb,
> unsigned int mtu)
> if (skb->ignore_df)
> return false;
>
> - if (skb_is_gso(skb) && skb_gso_validate_mtu(skb, mtu))
> + if (skb_is_gso(skb) && skb_gso_validate_network_len(skb, mtu))
> return false;
>
> return true;
> diff --git a/net/ipv6/netfilter/nf_flow_table_ipv6.c
> b/net/ipv6/netfilter/nf_flow_table_ipv6.c
> index d346705d6ee6..207cb35569b1 100644
> --- a/net/ipv6/netfilter/nf_flow_table_ipv6.c
> +++ b/net/ipv6/netfilter/nf_flow_table_ipv6.c
> @@ -178,7 +178,7 @@ static bool __nf_flow_exceeds_mtu(const struct sk_buff
> *skb, unsigned int mtu)
> if (skb->len <= mtu)
> return false;
>
> - if (skb_is_gso(skb) && skb_gso_validate_mtu(skb, mtu))
> + if (skb_is_gso(skb) && skb_gso_validate_network_len(skb, mtu))
> return false;
>
> return true;
> diff --git a/net/mpls/af_mpls.c b/net/mpls/af_mpls.c
> index e545a3c9365f..7a4de6d618b1 100644
> --- a/net/mpls/af_mpls.c
> +++ b/net/mpls/af_mpls.c
> @@ -122,7 +122,7 @@ bool mpls_pkt_too_big(const struct sk_buff *skb, unsigned
> int mtu)
> if (skb->len <= mtu)
> return false;
>
> - if (skb_is_gso(skb) && skb_gso_validate_mtu(skb, mtu))
> + if (skb_is_gso(skb) && skb_gso_validate_network_len(skb, mtu))
> return false;
>
> return true;
> diff --git a/net/xfrm/xfrm_device.c b/net/xfrm/xfrm_device.c
> index 8e70291e586a..e87d6c4dd5b6 100644
> --- a/net/xfrm/xfrm_device.c
> +++ b/net/xfrm/xfrm_device.c
> @@ -217,7 +217,7 @@ bool xfrm_dev_offload_ok(struct sk_buff *skb, struct
> xfrm_state *x)
> if (skb->len <= mtu)
> goto ok;
>
> - if (skb_is_gso(skb) && skb_gso_validate_mtu(skb, mtu))
> + if (skb_is_gso(skb) && skb_gso_validate_network_len(skb, mtu))
> goto ok;
> }
>
> --
> 2.14.1
>
