Commit d219df60 authored by Ziyang Xuan's avatar Ziyang Xuan Committed by Martin KaFai Lau
Browse files

bpf: Add ipip6 and ip6ip decap support for bpf_skb_adjust_room() 



Add ipip6 and ip6ip decap support for bpf_skb_adjust_room().
Main use case is for using cls_bpf on ingress hook to decapsulate
IPv4 over IPv6 and IPv6 over IPv4 tunnel packets.

Add two new flags BPF_F_ADJ_ROOM_DECAP_L3_IPV{4,6} to indicate the
new IP header version after decapsulating the outer IP header.

Suggested-by: default avatarWillem de Bruijn <willemb@google.com>
Signed-off-by: default avatarZiyang Xuan <william.xuanziyang@huawei.com>
Reviewed-by: default avatarWillem de Bruijn <willemb@google.com>
Link: https://lore.kernel.org/r/b268ec7f0ff9431f4f43b1b40ab856ebb28cb4e1.1673574419.git.william.xuanziyang@huawei.com


Signed-off-by: default avatarMartin KaFai Lau <martin.lau@kernel.org>
parent 1c48391b

include/uapi/linux/bpf.h

+7 −0
Original line number Diff line number Diff line
@@ -2647,6 +2647,11 @@ union bpf_attr { 
 *		  Use with BPF_F_ADJ_ROOM_ENCAP_L2 flag to further specify the

 *		  L2 type as Ethernet.

 *

 *		* **BPF_F_ADJ_ROOM_DECAP_L3_IPV4**,

 *		  **BPF_F_ADJ_ROOM_DECAP_L3_IPV6**:

 *		  Indicate the new IP header version after decapsulating the outer

 *		  IP header. Used when the inner and outer IP versions are different.

 *

 * 		A call to this helper is susceptible to change the underlying

 * 		packet buffer. Therefore, at load time, all checks on pointers

 * 		previously done by the verifier are invalidated and must be
@@ -5807,6 +5812,8 @@ enum { 
	BPF_F_ADJ_ROOM_ENCAP_L4_UDP	= (1ULL << 4),

	BPF_F_ADJ_ROOM_NO_CSUM_RESET	= (1ULL << 5),

	BPF_F_ADJ_ROOM_ENCAP_L2_ETH	= (1ULL << 6),

	BPF_F_ADJ_ROOM_DECAP_L3_IPV4	= (1ULL << 7),

	BPF_F_ADJ_ROOM_DECAP_L3_IPV6	= (1ULL << 8),

};



enum {

net/core/filter.c

+30 −1
Original line number Diff line number Diff line
@@ -3381,13 +3381,17 @@ static u32 bpf_skb_net_base_len(const struct sk_buff *skb) 
#define BPF_F_ADJ_ROOM_ENCAP_L3_MASK	(BPF_F_ADJ_ROOM_ENCAP_L3_IPV4 | \

					 BPF_F_ADJ_ROOM_ENCAP_L3_IPV6)



#define BPF_F_ADJ_ROOM_DECAP_L3_MASK	(BPF_F_ADJ_ROOM_DECAP_L3_IPV4 | \

					 BPF_F_ADJ_ROOM_DECAP_L3_IPV6)



#define BPF_F_ADJ_ROOM_MASK		(BPF_F_ADJ_ROOM_FIXED_GSO | \

					 BPF_F_ADJ_ROOM_ENCAP_L3_MASK | \

					 BPF_F_ADJ_ROOM_ENCAP_L4_GRE | \

					 BPF_F_ADJ_ROOM_ENCAP_L4_UDP | \

					 BPF_F_ADJ_ROOM_ENCAP_L2_ETH | \

					 BPF_F_ADJ_ROOM_ENCAP_L2( \

					  BPF_ADJ_ROOM_ENCAP_L2_MASK))

					  BPF_ADJ_ROOM_ENCAP_L2_MASK) | \

					 BPF_F_ADJ_ROOM_DECAP_L3_MASK)



static int bpf_skb_net_grow(struct sk_buff *skb, u32 off, u32 len_diff,

			    u64 flags)
@@ -3501,6 +3505,7 @@ static int bpf_skb_net_shrink(struct sk_buff *skb, u32 off, u32 len_diff, 
	int ret;



	if (unlikely(flags & ~(BPF_F_ADJ_ROOM_FIXED_GSO |

			       BPF_F_ADJ_ROOM_DECAP_L3_MASK |

			       BPF_F_ADJ_ROOM_NO_CSUM_RESET)))

		return -EINVAL;
@@ -3519,6 +3524,14 @@ static int bpf_skb_net_shrink(struct sk_buff *skb, u32 off, u32 len_diff, 
	if (unlikely(ret < 0))

		return ret;



	/* Match skb->protocol to new outer l3 protocol */

	if (skb->protocol == htons(ETH_P_IP) &&

	    flags & BPF_F_ADJ_ROOM_DECAP_L3_IPV6)

		skb->protocol = htons(ETH_P_IPV6);

	else if (skb->protocol == htons(ETH_P_IPV6) &&

		 flags & BPF_F_ADJ_ROOM_DECAP_L3_IPV4)

		skb->protocol = htons(ETH_P_IP);



	if (skb_is_gso(skb)) {

		struct skb_shared_info *shinfo = skb_shinfo(skb);
@@ -3608,6 +3621,22 @@ BPF_CALL_4(bpf_skb_adjust_room, struct sk_buff *, skb, s32, len_diff, 
		return -ENOTSUPP;

	}



	if (flags & BPF_F_ADJ_ROOM_DECAP_L3_MASK) {

		if (!shrink)

			return -EINVAL;



		switch (flags & BPF_F_ADJ_ROOM_DECAP_L3_MASK) {

		case BPF_F_ADJ_ROOM_DECAP_L3_IPV4:

			len_min = sizeof(struct iphdr);

			break;

		case BPF_F_ADJ_ROOM_DECAP_L3_IPV6:

			len_min = sizeof(struct ipv6hdr);

			break;

		default:

			return -EINVAL;

		}

	}



	len_cur = skb->len - skb_network_offset(skb);

	if ((shrink && (len_diff_abs >= len_cur ||

			len_cur - len_diff_abs < len_min)) ||

tools/include/uapi/linux/bpf.h

+7 −0
Original line number Diff line number Diff line
@@ -2647,6 +2647,11 @@ union bpf_attr { 
 *		  Use with BPF_F_ADJ_ROOM_ENCAP_L2 flag to further specify the

 *		  L2 type as Ethernet.

 *

 *		* **BPF_F_ADJ_ROOM_DECAP_L3_IPV4**,

 *		  **BPF_F_ADJ_ROOM_DECAP_L3_IPV6**:

 *		  Indicate the new IP header version after decapsulating the outer

 *		  IP header. Used when the inner and outer IP versions are different.

 *

 * 		A call to this helper is susceptible to change the underlying

 * 		packet buffer. Therefore, at load time, all checks on pointers

 * 		previously done by the verifier are invalidated and must be
@@ -5807,6 +5812,8 @@ enum { 
	BPF_F_ADJ_ROOM_ENCAP_L4_UDP	= (1ULL << 4),

	BPF_F_ADJ_ROOM_NO_CSUM_RESET	= (1ULL << 5),

	BPF_F_ADJ_ROOM_ENCAP_L2_ETH	= (1ULL << 6),

	BPF_F_ADJ_ROOM_DECAP_L3_IPV4    = (1ULL << 7),

	BPF_F_ADJ_ROOM_DECAP_L3_IPV6    = (1ULL << 8),

};



enum {