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	bpf: only adjust gso_size on bytestream protocols
bpf_skb_change_proto and bpf_skb_adjust_room change skb header length. For GSO packets they adjust gso_size to maintain the same MTU. The gso size can only be safely adjusted on bytestream protocols. Commitd02f51cbcf("bpf: fix bpf_skb_adjust_net/bpf_skb_proto_xlat to deal with gso sctp skbs") excluded SKB_GSO_SCTP. Since then type SKB_GSO_UDP_L4 has been added, whose contents are one gso_size unit per datagram. Also exclude these. Move from a blacklist to a whitelist check to future proof against additional such new GSO types, e.g., for fraglist based GRO. Fixes:bec1f6f697("udp: generate gso with UDP_SEGMENT") Signed-off-by: Willem de Bruijn <willemb@google.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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					 2 changed files with 10 additions and 8 deletions
				
			
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			@ -4212,6 +4212,12 @@ static inline bool skb_is_gso_sctp(const struct sk_buff *skb)
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	return skb_shinfo(skb)->gso_type & SKB_GSO_SCTP;
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}
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static inline bool skb_is_gso_tcp(const struct sk_buff *skb)
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{
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	return skb_is_gso(skb) &&
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	       skb_shinfo(skb)->gso_type & (SKB_GSO_TCPV4 | SKB_GSO_TCPV6);
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}
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static inline void skb_gso_reset(struct sk_buff *skb)
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{
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	skb_shinfo(skb)->gso_size = 0;
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			@ -2789,8 +2789,7 @@ static int bpf_skb_proto_4_to_6(struct sk_buff *skb)
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	u32 off = skb_mac_header_len(skb);
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	int ret;
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	/* SCTP uses GSO_BY_FRAGS, thus cannot adjust it. */
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	if (skb_is_gso(skb) && unlikely(skb_is_gso_sctp(skb)))
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	if (!skb_is_gso_tcp(skb))
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		return -ENOTSUPP;
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	ret = skb_cow(skb, len_diff);
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			@ -2831,8 +2830,7 @@ static int bpf_skb_proto_6_to_4(struct sk_buff *skb)
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	u32 off = skb_mac_header_len(skb);
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	int ret;
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	/* SCTP uses GSO_BY_FRAGS, thus cannot adjust it. */
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	if (skb_is_gso(skb) && unlikely(skb_is_gso_sctp(skb)))
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	if (!skb_is_gso_tcp(skb))
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		return -ENOTSUPP;
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	ret = skb_unclone(skb, GFP_ATOMIC);
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			@ -2957,8 +2955,7 @@ static int bpf_skb_net_grow(struct sk_buff *skb, u32 len_diff)
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	u32 off = skb_mac_header_len(skb) + bpf_skb_net_base_len(skb);
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	int ret;
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	/* SCTP uses GSO_BY_FRAGS, thus cannot adjust it. */
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	if (skb_is_gso(skb) && unlikely(skb_is_gso_sctp(skb)))
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	if (!skb_is_gso_tcp(skb))
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		return -ENOTSUPP;
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	ret = skb_cow(skb, len_diff);
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			@ -2987,8 +2984,7 @@ static int bpf_skb_net_shrink(struct sk_buff *skb, u32 len_diff)
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	u32 off = skb_mac_header_len(skb) + bpf_skb_net_base_len(skb);
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	int ret;
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	/* SCTP uses GSO_BY_FRAGS, thus cannot adjust it. */
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	if (skb_is_gso(skb) && unlikely(skb_is_gso_sctp(skb)))
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	if (!skb_is_gso_tcp(skb))
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		return -ENOTSUPP;
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	ret = skb_unclone(skb, GFP_ATOMIC);
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