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Commit 8a31db56 authored by John Fastabend's avatar John Fastabend Committed by David S. Miller
Browse files

bpf: add access to sock fields and pkt data from sk_skb programs 



Signed-off-by: default avatarJohn Fastabend <john.fastabend@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 174a79ff

include/uapi/linux/bpf.h

+9 −0
Original line number Diff line number Diff line
@@ -712,6 +712,15 @@ struct __sk_buff { 
	__u32 data;

	__u32 data_end;

	__u32 napi_id;



	/* accessed by BPF_PROG_TYPE_sk_skb types */

	__u32 family;

	__u32 remote_ip4;	/* Stored in network byte order */

	__u32 local_ip4;	/* Stored in network byte order */

	__u32 remote_ip6[4];	/* Stored in network byte order */

	__u32 local_ip6[4];	/* Stored in network byte order */

	__u32 remote_port;	/* Stored in network byte order */

	__u32 local_port;	/* stored in host byte order */

};



struct bpf_tunnel_key {

kernel/bpf/verifier.c

+1 −0
Original line number Diff line number Diff line
@@ -886,6 +886,7 @@ static bool may_access_direct_pkt_data(struct bpf_verifier_env *env, 
	case BPF_PROG_TYPE_SCHED_ACT:

	case BPF_PROG_TYPE_XDP:

	case BPF_PROG_TYPE_LWT_XMIT:

	case BPF_PROG_TYPE_SK_SKB:

		if (meta)

			return meta->pkt_access;

net/core/filter.c

+169 −0
Original line number Diff line number Diff line
@@ -3278,8 +3278,16 @@ static const struct bpf_func_proto * 
static const struct bpf_func_proto *sk_skb_func_proto(enum bpf_func_id func_id)

{

	switch (func_id) {

	case BPF_FUNC_skb_store_bytes:

		return &bpf_skb_store_bytes_proto;

	case BPF_FUNC_skb_load_bytes:

		return &bpf_skb_load_bytes_proto;

	case BPF_FUNC_skb_pull_data:

		return &bpf_skb_pull_data_proto;

	case BPF_FUNC_skb_change_tail:

		return &bpf_skb_change_tail_proto;

	case BPF_FUNC_skb_change_head:

		return &bpf_skb_change_head_proto;

	case BPF_FUNC_get_socket_cookie:

		return &bpf_get_socket_cookie_proto;

	case BPF_FUNC_get_socket_uid:
@@ -3343,6 +3351,10 @@ static bool bpf_skb_is_valid_access(int off, int size, enum bpf_access_type type 
		if (off + size > offsetofend(struct __sk_buff, cb[4]))

			return false;

		break;

	case bpf_ctx_range_till(struct __sk_buff, remote_ip6[0], remote_ip6[3]):

	case bpf_ctx_range_till(struct __sk_buff, local_ip6[0], local_ip6[3]):

	case bpf_ctx_range_till(struct __sk_buff, remote_ip4, remote_ip4):

	case bpf_ctx_range_till(struct __sk_buff, local_ip4, local_ip4):

	case bpf_ctx_range(struct __sk_buff, data):

	case bpf_ctx_range(struct __sk_buff, data_end):

		if (size != size_default)
@@ -3371,6 +3383,7 @@ static bool sk_filter_is_valid_access(int off, int size, 
	case bpf_ctx_range(struct __sk_buff, tc_classid):

	case bpf_ctx_range(struct __sk_buff, data):

	case bpf_ctx_range(struct __sk_buff, data_end):

	case bpf_ctx_range_till(struct __sk_buff, family, local_port):

		return false;

	}
@@ -3392,6 +3405,7 @@ static bool lwt_is_valid_access(int off, int size, 
{

	switch (off) {

	case bpf_ctx_range(struct __sk_buff, tc_classid):

	case bpf_ctx_range_till(struct __sk_buff, family, local_port):

		return false;

	}
@@ -3505,6 +3519,8 @@ static bool tc_cls_act_is_valid_access(int off, int size, 
	case bpf_ctx_range(struct __sk_buff, data_end):

		info->reg_type = PTR_TO_PACKET_END;

		break;

	case bpf_ctx_range_till(struct __sk_buff, family, local_port):

		return false;

	}



	return bpf_skb_is_valid_access(off, size, type, info);
@@ -3582,11 +3598,63 @@ static bool sock_ops_is_valid_access(int off, int size, 
	return __is_valid_sock_ops_access(off, size);

}



static int sk_skb_prologue(struct bpf_insn *insn_buf, bool direct_write,

			   const struct bpf_prog *prog)

{

	struct bpf_insn *insn = insn_buf;



	if (!direct_write)

		return 0;



	/* if (!skb->cloned)

	 *       goto start;

	 *

	 * (Fast-path, otherwise approximation that we might be

	 *  a clone, do the rest in helper.)

	 */

	*insn++ = BPF_LDX_MEM(BPF_B, BPF_REG_6, BPF_REG_1, CLONED_OFFSET());

	*insn++ = BPF_ALU32_IMM(BPF_AND, BPF_REG_6, CLONED_MASK);

	*insn++ = BPF_JMP_IMM(BPF_JEQ, BPF_REG_6, 0, 7);



	/* ret = bpf_skb_pull_data(skb, 0); */

	*insn++ = BPF_MOV64_REG(BPF_REG_6, BPF_REG_1);

	*insn++ = BPF_ALU64_REG(BPF_XOR, BPF_REG_2, BPF_REG_2);

	*insn++ = BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,

			       BPF_FUNC_skb_pull_data);

	/* if (!ret)

	 *      goto restore;

	 * return SK_DROP;

	 */

	*insn++ = BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 2);

	*insn++ = BPF_ALU32_IMM(BPF_MOV, BPF_REG_0, SK_DROP);

	*insn++ = BPF_EXIT_INSN();



	/* restore: */

	*insn++ = BPF_MOV64_REG(BPF_REG_1, BPF_REG_6);

	/* start: */

	*insn++ = prog->insnsi[0];



	return insn - insn_buf;

}



static bool sk_skb_is_valid_access(int off, int size,

				   enum bpf_access_type type,

				   struct bpf_insn_access_aux *info)

{

	if (type == BPF_WRITE) {

		switch (off) {

		case bpf_ctx_range(struct __sk_buff, mark):

		case bpf_ctx_range(struct __sk_buff, tc_index):

		case bpf_ctx_range(struct __sk_buff, priority):

			break;

		default:

			return false;

		}

	}



	switch (off) {

	case bpf_ctx_range(struct __sk_buff, tc_classid):

		return false;

	case bpf_ctx_range(struct __sk_buff, data):

		info->reg_type = PTR_TO_PACKET;

		break;
@@ -3783,6 +3851,106 @@ static u32 bpf_convert_ctx_access(enum bpf_access_type type, 
		*insn++ = BPF_MOV64_IMM(si->dst_reg, 0);

#endif

		break;

	case offsetof(struct __sk_buff, family):

		BUILD_BUG_ON(FIELD_SIZEOF(struct sock_common, skc_family) != 2);



		*insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct sk_buff, sk),

				      si->dst_reg, si->src_reg,

				      offsetof(struct sk_buff, sk));

		*insn++ = BPF_LDX_MEM(BPF_H, si->dst_reg, si->dst_reg,

				      bpf_target_off(struct sock_common,

						     skc_family,

						     2, target_size));

		break;

	case offsetof(struct __sk_buff, remote_ip4):

		BUILD_BUG_ON(FIELD_SIZEOF(struct sock_common, skc_daddr) != 4);



		*insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct sk_buff, sk),

				      si->dst_reg, si->src_reg,

				      offsetof(struct sk_buff, sk));

		*insn++ = BPF_LDX_MEM(BPF_W, si->dst_reg, si->dst_reg,

				      bpf_target_off(struct sock_common,

						     skc_daddr,

						     4, target_size));

		break;

	case offsetof(struct __sk_buff, local_ip4):

		BUILD_BUG_ON(FIELD_SIZEOF(struct sock_common,

					  skc_rcv_saddr) != 4);



		*insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct sk_buff, sk),

				      si->dst_reg, si->src_reg,

				      offsetof(struct sk_buff, sk));

		*insn++ = BPF_LDX_MEM(BPF_W, si->dst_reg, si->dst_reg,

				      bpf_target_off(struct sock_common,

						     skc_rcv_saddr,

						     4, target_size));

		break;

	case offsetof(struct __sk_buff, remote_ip6[0]) ...

	     offsetof(struct __sk_buff, remote_ip6[3]):

#if IS_ENABLED(CONFIG_IPV6)

		BUILD_BUG_ON(FIELD_SIZEOF(struct sock_common,

					  skc_v6_daddr.s6_addr32[0]) != 4);



		off = si->off;

		off -= offsetof(struct __sk_buff, remote_ip6[0]);



		*insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct sk_buff, sk),

				      si->dst_reg, si->src_reg,

				      offsetof(struct sk_buff, sk));

		*insn++ = BPF_LDX_MEM(BPF_W, si->dst_reg, si->dst_reg,

				      offsetof(struct sock_common,

					       skc_v6_daddr.s6_addr32[0]) +

				      off);

#else

		*insn++ = BPF_MOV32_IMM(si->dst_reg, 0);

#endif

		break;

	case offsetof(struct __sk_buff, local_ip6[0]) ...

	     offsetof(struct __sk_buff, local_ip6[3]):

#if IS_ENABLED(CONFIG_IPV6)

		BUILD_BUG_ON(FIELD_SIZEOF(struct sock_common,

					  skc_v6_rcv_saddr.s6_addr32[0]) != 4);



		off = si->off;

		off -= offsetof(struct __sk_buff, local_ip6[0]);



		*insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct sk_buff, sk),

				      si->dst_reg, si->src_reg,

				      offsetof(struct sk_buff, sk));

		*insn++ = BPF_LDX_MEM(BPF_W, si->dst_reg, si->dst_reg,

				      offsetof(struct sock_common,

					       skc_v6_rcv_saddr.s6_addr32[0]) +

				      off);

#else

		*insn++ = BPF_MOV32_IMM(si->dst_reg, 0);

#endif

		break;



	case offsetof(struct __sk_buff, remote_port):

		BUILD_BUG_ON(FIELD_SIZEOF(struct sock_common, skc_dport) != 2);



		*insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct sk_buff, sk),

				      si->dst_reg, si->src_reg,

				      offsetof(struct sk_buff, sk));

		*insn++ = BPF_LDX_MEM(BPF_H, si->dst_reg, si->dst_reg,

				      bpf_target_off(struct sock_common,

						     skc_dport,

						     2, target_size));

#ifndef __BIG_ENDIAN_BITFIELD

		*insn++ = BPF_ALU32_IMM(BPF_LSH, si->dst_reg, 16);

#endif

		break;



	case offsetof(struct __sk_buff, local_port):

		BUILD_BUG_ON(FIELD_SIZEOF(struct sock_common, skc_num) != 2);



		*insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct sk_buff, sk),

				      si->dst_reg, si->src_reg,

				      offsetof(struct sk_buff, sk));

		*insn++ = BPF_LDX_MEM(BPF_H, si->dst_reg, si->dst_reg,

				      bpf_target_off(struct sock_common,

						     skc_num, 2, target_size));

		break;

	}



	return insn - insn_buf;
@@ -4071,6 +4239,7 @@ const struct bpf_verifier_ops sk_skb_prog_ops = { 
	.get_func_proto		= sk_skb_func_proto,

	.is_valid_access	= sk_skb_is_valid_access,

	.convert_ctx_access	= bpf_convert_ctx_access,

	.gen_prologue		= sk_skb_prologue,

};



int sk_detach_filter(struct sock *sk)