Commit 0e25d14e authored by Daniel Borkmann's avatar Daniel Borkmann
Browse files

Merge branch 'bpf-xfrm-states' 



Eyal Birger says:

====================
This patchset adds support for fetching XFRM state information from
an eBPF program called from TC.

The first patch introduces a helper for fetching an XFRM state from the
skb's secpath. The XFRM state is modeled using a new virtual struct which
contains the SPI, peer address, and reqid values of the state; This struct
can be extended in the future to provide additional state information.

The second patch adds a test example in test_tunnel_bpf.sh. The sample
validates the correct extraction of state information by the eBPF program.

v3:
  - Kept SPI and peer IPv4 address in state in network byte order
    following suggestion from Alexei Starovoitov
v2:
  - Fixed two comments by Daniel Borkmann:
    - disallow reserved flags in helper call
    - avoid compiling in helper code when CONFIG_XFRM is off
====================

Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
parents fbcf93eb 29a36f9e

include/uapi/linux/bpf.h

+24 −1
Original line number Diff line number Diff line
@@ -774,6 +774,15 @@ union bpf_attr { 
 *     @xdp_md: pointer to xdp_md

 *     @delta: A negative integer to be added to xdp_md.data_end

 *     Return: 0 on success or negative on error

 *

 * int bpf_skb_get_xfrm_state(skb, index, xfrm_state, size, flags)

 *     retrieve XFRM state

 *     @skb: pointer to skb

 *     @index: index of the xfrm state in the secpath

 *     @key: pointer to 'struct bpf_xfrm_state'

 *     @size: size of 'struct bpf_xfrm_state'

 *     @flags: room for future extensions

 *     Return: 0 on success or negative error

 */

#define __BPF_FUNC_MAPPER(FN)		\

	FN(unspec),			\
@@ -841,7 +850,8 @@ union bpf_attr { 
	FN(msg_cork_bytes),		\

	FN(msg_pull_data),		\

	FN(bind),			\

	FN(xdp_adjust_tail),

	FN(xdp_adjust_tail),		\

	FN(skb_get_xfrm_state),



/* integer value in 'imm' field of BPF_CALL instruction selects which helper

 * function eBPF program intends to call
@@ -947,6 +957,19 @@ struct bpf_tunnel_key { 
	__u32 tunnel_label;

};



/* user accessible mirror of in-kernel xfrm_state.

 * new fields can only be added to the end of this structure

 */

struct bpf_xfrm_state {

	__u32 reqid;

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

	__u16 family;

	union {

		__u32 remote_ipv4;	/* Stored in network byte order */

		__u32 remote_ipv6[4];	/* Stored in network byte order */

	};

};



/* Generic BPF return codes which all BPF program types may support.

 * The values are binary compatible with their TC_ACT_* counter-part to

 * provide backwards compatibility with existing SCHED_CLS and SCHED_ACT

net/core/filter.c

+48 −0
Original line number Diff line number Diff line
@@ -57,6 +57,7 @@ 
#include <net/sock_reuseport.h>

#include <net/busy_poll.h>

#include <net/tcp.h>

#include <net/xfrm.h>

#include <linux/bpf_trace.h>



/**
@@ -3743,6 +3744,49 @@ static const struct bpf_func_proto bpf_bind_proto = { 
	.arg3_type	= ARG_CONST_SIZE,

};



#ifdef CONFIG_XFRM

BPF_CALL_5(bpf_skb_get_xfrm_state, struct sk_buff *, skb, u32, index,

	   struct bpf_xfrm_state *, to, u32, size, u64, flags)

{

	const struct sec_path *sp = skb_sec_path(skb);

	const struct xfrm_state *x;



	if (!sp || unlikely(index >= sp->len || flags))

		goto err_clear;



	x = sp->xvec[index];



	if (unlikely(size != sizeof(struct bpf_xfrm_state)))

		goto err_clear;



	to->reqid = x->props.reqid;

	to->spi = x->id.spi;

	to->family = x->props.family;

	if (to->family == AF_INET6) {

		memcpy(to->remote_ipv6, x->props.saddr.a6,

		       sizeof(to->remote_ipv6));

	} else {

		to->remote_ipv4 = x->props.saddr.a4;

	}



	return 0;

err_clear:

	memset(to, 0, size);

	return -EINVAL;

}



static const struct bpf_func_proto bpf_skb_get_xfrm_state_proto = {

	.func		= bpf_skb_get_xfrm_state,

	.gpl_only	= false,

	.ret_type	= RET_INTEGER,

	.arg1_type	= ARG_PTR_TO_CTX,

	.arg2_type	= ARG_ANYTHING,

	.arg3_type	= ARG_PTR_TO_UNINIT_MEM,

	.arg4_type	= ARG_CONST_SIZE,

	.arg5_type	= ARG_ANYTHING,

};

#endif



static const struct bpf_func_proto *

bpf_base_func_proto(enum bpf_func_id func_id)

{
@@ -3884,6 +3928,10 @@ tc_cls_act_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) 
		return &bpf_get_socket_cookie_proto;

	case BPF_FUNC_get_socket_uid:

		return &bpf_get_socket_uid_proto;

#ifdef CONFIG_XFRM

	case BPF_FUNC_skb_get_xfrm_state:

		return &bpf_skb_get_xfrm_state_proto;

#endif

	default:

		return bpf_base_func_proto(func_id);

	}

samples/bpf/tcbpf2_kern.c

+16 −0
Original line number Diff line number Diff line
@@ -593,4 +593,20 @@ int _ip6ip6_get_tunnel(struct __sk_buff *skb) 
	return TC_ACT_OK;

}



SEC("xfrm_get_state")

int _xfrm_get_state(struct __sk_buff *skb)

{

	struct bpf_xfrm_state x;

	char fmt[] = "reqid %d spi 0x%x remote ip 0x%x\n";

	int ret;



	ret = bpf_skb_get_xfrm_state(skb, 0, &x, sizeof(x), 0);

	if (ret < 0)

		return TC_ACT_OK;



	bpf_trace_printk(fmt, sizeof(fmt), x.reqid, bpf_ntohl(x.spi),

			 bpf_ntohl(x.remote_ipv4));

	return TC_ACT_OK;

}



char _license[] SEC("license") = "GPL";

samples/bpf/test_tunnel_bpf.sh

+71 −0
Original line number Diff line number Diff line
@@ -155,6 +155,57 @@ function add_ipip_tunnel { 
	ip addr add dev $DEV 10.1.1.200/24

}



function setup_xfrm_tunnel {

	auth=0x$(printf '1%.0s' {1..40})

	enc=0x$(printf '2%.0s' {1..32})

	spi_in_to_out=0x1

	spi_out_to_in=0x2

	# in namespace

	# in -> out

	ip netns exec at_ns0 \

		ip xfrm state add src 172.16.1.100 dst 172.16.1.200 proto esp \

			spi $spi_in_to_out reqid 1 mode tunnel \

			auth-trunc 'hmac(sha1)' $auth 96 enc 'cbc(aes)' $enc

	ip netns exec at_ns0 \

		ip xfrm policy add src 10.1.1.100/32 dst 10.1.1.200/32 dir out \

		tmpl src 172.16.1.100 dst 172.16.1.200 proto esp reqid 1 \

		mode tunnel

	# out -> in

	ip netns exec at_ns0 \

		ip xfrm state add src 172.16.1.200 dst 172.16.1.100 proto esp \

			spi $spi_out_to_in reqid 2 mode tunnel \

			auth-trunc 'hmac(sha1)' $auth 96 enc 'cbc(aes)' $enc

	ip netns exec at_ns0 \

		ip xfrm policy add src 10.1.1.200/32 dst 10.1.1.100/32 dir in \

		tmpl src 172.16.1.200 dst 172.16.1.100 proto esp reqid 2 \

		mode tunnel

	# address & route

	ip netns exec at_ns0 \

		ip addr add dev veth0 10.1.1.100/32

	ip netns exec at_ns0 \

		ip route add 10.1.1.200 dev veth0 via 172.16.1.200 \

			src 10.1.1.100



	# out of namespace

	# in -> out

	ip xfrm state add src 172.16.1.100 dst 172.16.1.200 proto esp \

		spi $spi_in_to_out reqid 1 mode tunnel \

		auth-trunc 'hmac(sha1)' $auth 96  enc 'cbc(aes)' $enc

	ip xfrm policy add src 10.1.1.100/32 dst 10.1.1.200/32 dir in \

		tmpl src 172.16.1.100 dst 172.16.1.200 proto esp reqid 1 \

		mode tunnel

	# out -> in

	ip xfrm state add src 172.16.1.200 dst 172.16.1.100 proto esp \

		spi $spi_out_to_in reqid 2 mode tunnel \

		auth-trunc 'hmac(sha1)' $auth 96  enc 'cbc(aes)' $enc

	ip xfrm policy add src 10.1.1.200/32 dst 10.1.1.100/32 dir out \

		tmpl src 172.16.1.200 dst 172.16.1.100 proto esp reqid 2 \

		mode tunnel

	# address & route

	ip addr add dev veth1 10.1.1.200/32

	ip route add 10.1.1.100 dev veth1 via 172.16.1.100 src 10.1.1.200

}



function attach_bpf {

	DEV=$1

	SET_TUNNEL=$2
@@ -278,6 +329,22 @@ function test_ipip { 
	cleanup

}



function test_xfrm_tunnel {

	config_device

        tcpdump -nei veth1 ip &

	output=$(mktemp)

	cat /sys/kernel/debug/tracing/trace_pipe | tee $output &

        setup_xfrm_tunnel

	tc qdisc add dev veth1 clsact

	tc filter add dev veth1 proto ip ingress bpf da obj tcbpf2_kern.o \

		sec xfrm_get_state

	ip netns exec at_ns0 ping -c 1 10.1.1.200

	grep "reqid 1" $output

	grep "spi 0x1" $output

	grep "remote ip 0xac100164" $output

	cleanup

}



function cleanup {

	set +ex

	pkill iperf
@@ -291,6 +358,8 @@ function cleanup { 
	ip link del geneve11

	ip link del erspan11

	ip link del ip6erspan11

	ip x s flush

	ip x p flush

	pkill tcpdump

	pkill cat

	set -ex
@@ -316,4 +385,6 @@ echo "Testing GENEVE tunnel..." 
test_geneve

echo "Testing IPIP tunnel..."

test_ipip

echo "Testing IPSec tunnel..."

test_xfrm_tunnel

echo "*** PASS ***"

tools/include/uapi/linux/bpf.h

+24 −1
Original line number Diff line number Diff line
@@ -774,6 +774,15 @@ union bpf_attr { 
 *     @xdp_md: pointer to xdp_md

 *     @delta: A negative integer to be added to xdp_md.data_end

 *     Return: 0 on success or negative on error

 *

 * int bpf_skb_get_xfrm_state(skb, index, xfrm_state, size, flags)

 *     retrieve XFRM state

 *     @skb: pointer to skb

 *     @index: index of the xfrm state in the secpath

 *     @key: pointer to 'struct bpf_xfrm_state'

 *     @size: size of 'struct bpf_xfrm_state'

 *     @flags: room for future extensions

 *     Return: 0 on success or negative error

 */

#define __BPF_FUNC_MAPPER(FN)		\

	FN(unspec),			\
@@ -841,7 +850,8 @@ union bpf_attr { 
	FN(msg_cork_bytes),		\

	FN(msg_pull_data),		\

	FN(bind),			\

	FN(xdp_adjust_tail),

	FN(xdp_adjust_tail),		\

	FN(skb_get_xfrm_state),



/* integer value in 'imm' field of BPF_CALL instruction selects which helper

 * function eBPF program intends to call
@@ -946,6 +956,19 @@ struct bpf_tunnel_key { 
	__u32 tunnel_label;

};



/* user accessible mirror of in-kernel xfrm_state.

 * new fields can only be added to the end of this structure

 */

struct bpf_xfrm_state {

	__u32 reqid;

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

	__u16 family;

	union {

		__u32 remote_ipv4;	/* Stored in network byte order */

		__u32 remote_ipv6[4];	/* Stored in network byte order */

	};

};



/* Generic BPF return codes which all BPF program types may support.

 * The values are binary compatible with their TC_ACT_* counter-part to

 * provide backwards compatibility with existing SCHED_CLS and SCHED_ACT

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