Commit 614cd3bd authored by Alexei Starovoitov's avatar Alexei Starovoitov Committed by David S. Miller
Browse files

samples: bpf: add skb->field examples and tests 



- modify sockex1 example to count number of bytes in outgoing packets
- modify sockex2 example to count number of bytes and packets per flow
- add 4 stress tests that exercise 'skb->field' code path of verifier

Signed-off-by: default avatarAlexei Starovoitov <ast@plumgrid.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 9bac3d6d

samples/bpf/sockex1_kern.c

+6 −2
Original line number Diff line number Diff line 
#include <uapi/linux/bpf.h>

#include <uapi/linux/if_ether.h>

#include <uapi/linux/if_packet.h>

#include <uapi/linux/ip.h>

#include "bpf_helpers.h"
@@ -11,14 +12,17 @@ struct bpf_map_def SEC("maps") my_map = { 
};



SEC("socket1")

int bpf_prog1(struct sk_buff *skb)

int bpf_prog1(struct __sk_buff *skb)

{

	int index = load_byte(skb, ETH_HLEN + offsetof(struct iphdr, protocol));

	long *value;



	if (skb->pkt_type != PACKET_OUTGOING)

		return 0;



	value = bpf_map_lookup_elem(&my_map, &index);

	if (value)

		__sync_fetch_and_add(value, 1);

		__sync_fetch_and_add(value, skb->len);



	return 0;

}

samples/bpf/sockex1_user.c

+1 −1
Original line number Diff line number Diff line
@@ -40,7 +40,7 @@ int main(int ac, char **argv) 
		key = IPPROTO_ICMP;

		assert(bpf_lookup_elem(map_fd[0], &key, &icmp_cnt) == 0);



		printf("TCP %lld UDP %lld ICMP %lld packets\n",

		printf("TCP %lld UDP %lld ICMP %lld bytes\n",

		       tcp_cnt, udp_cnt, icmp_cnt);

		sleep(1);

	}

samples/bpf/sockex2_kern.c

+16 −10
Original line number Diff line number Diff line
@@ -42,13 +42,13 @@ static inline int proto_ports_offset(__u64 proto) 
	}

}



static inline int ip_is_fragment(struct sk_buff *ctx, __u64 nhoff)

static inline int ip_is_fragment(struct __sk_buff *ctx, __u64 nhoff)

{

	return load_half(ctx, nhoff + offsetof(struct iphdr, frag_off))

		& (IP_MF | IP_OFFSET);

}



static inline __u32 ipv6_addr_hash(struct sk_buff *ctx, __u64 off)

static inline __u32 ipv6_addr_hash(struct __sk_buff *ctx, __u64 off)

{

	__u64 w0 = load_word(ctx, off);

	__u64 w1 = load_word(ctx, off + 4);
@@ -58,7 +58,7 @@ static inline __u32 ipv6_addr_hash(struct sk_buff *ctx, __u64 off) 
	return (__u32)(w0 ^ w1 ^ w2 ^ w3);

}



static inline __u64 parse_ip(struct sk_buff *skb, __u64 nhoff, __u64 *ip_proto,

static inline __u64 parse_ip(struct __sk_buff *skb, __u64 nhoff, __u64 *ip_proto,

			     struct flow_keys *flow)

{

	__u64 verlen;
@@ -82,7 +82,7 @@ static inline __u64 parse_ip(struct sk_buff *skb, __u64 nhoff, __u64 *ip_proto, 
	return nhoff;

}



static inline __u64 parse_ipv6(struct sk_buff *skb, __u64 nhoff, __u64 *ip_proto,

static inline __u64 parse_ipv6(struct __sk_buff *skb, __u64 nhoff, __u64 *ip_proto,

			       struct flow_keys *flow)

{

	*ip_proto = load_byte(skb,
@@ -96,7 +96,7 @@ static inline __u64 parse_ipv6(struct sk_buff *skb, __u64 nhoff, __u64 *ip_proto 
	return nhoff;

}



static inline bool flow_dissector(struct sk_buff *skb, struct flow_keys *flow)

static inline bool flow_dissector(struct __sk_buff *skb, struct flow_keys *flow)

{

	__u64 nhoff = ETH_HLEN;

	__u64 ip_proto;
@@ -183,18 +183,23 @@ static inline bool flow_dissector(struct sk_buff *skb, struct flow_keys *flow) 
	return true;

}



struct pair {

	long packets;

	long bytes;

};



struct bpf_map_def SEC("maps") hash_map = {

	.type = BPF_MAP_TYPE_HASH,

	.key_size = sizeof(__be32),

	.value_size = sizeof(long),

	.value_size = sizeof(struct pair),

	.max_entries = 1024,

};



SEC("socket2")

int bpf_prog2(struct sk_buff *skb)

int bpf_prog2(struct __sk_buff *skb)

{

	struct flow_keys flow;

	long *value;

	struct pair *value;

	u32 key;



	if (!flow_dissector(skb, &flow))
@@ -203,9 +208,10 @@ int bpf_prog2(struct sk_buff *skb) 
	key = flow.dst;

	value = bpf_map_lookup_elem(&hash_map, &key);

	if (value) {

		__sync_fetch_and_add(value, 1);

		__sync_fetch_and_add(&value->packets, 1);

		__sync_fetch_and_add(&value->bytes, skb->len);

	} else {

		long val = 1;

		struct pair val = {1, skb->len};



		bpf_map_update_elem(&hash_map, &key, &val, BPF_ANY);

	}

samples/bpf/sockex2_user.c

+8 −3
Original line number Diff line number Diff line
@@ -6,6 +6,11 @@ 
#include <unistd.h>

#include <arpa/inet.h>



struct pair {

	__u64 packets;

	__u64 bytes;

};



int main(int ac, char **argv)

{

	char filename[256];
@@ -29,13 +34,13 @@ int main(int ac, char **argv) 


	for (i = 0; i < 5; i++) {

		int key = 0, next_key;

		long long value;

		struct pair value;



		while (bpf_get_next_key(map_fd[0], &key, &next_key) == 0) {

			bpf_lookup_elem(map_fd[0], &next_key, &value);

			printf("ip %s count %lld\n",

			printf("ip %s bytes %lld packets %lld\n",

			       inet_ntoa((struct in_addr){htonl(next_key)}),

			       value);

			       value.bytes, value.packets);

			key = next_key;

		}

		sleep(1);

samples/bpf/test_verifier.c

+70 −0
Original line number Diff line number Diff line
@@ -14,6 +14,7 @@ 
#include <linux/unistd.h>

#include <string.h>

#include <linux/filter.h>

#include <stddef.h>

#include "libbpf.h"



#define MAX_INSNS 512
@@ -642,6 +643,75 @@ static struct bpf_test tests[] = { 
		},

		.result = ACCEPT,

	},

	{

		"access skb fields ok",

		.insns = {

			BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_1,

				    offsetof(struct __sk_buff, len)),

			BPF_JMP_IMM(BPF_JGE, BPF_REG_0, 0, 1),

			BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_1,

				    offsetof(struct __sk_buff, mark)),

			BPF_JMP_IMM(BPF_JGE, BPF_REG_0, 0, 1),

			BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_1,

				    offsetof(struct __sk_buff, pkt_type)),

			BPF_JMP_IMM(BPF_JGE, BPF_REG_0, 0, 1),

			BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_1,

				    offsetof(struct __sk_buff, queue_mapping)),

			BPF_JMP_IMM(BPF_JGE, BPF_REG_0, 0, 0),

			BPF_EXIT_INSN(),

		},

		.result = ACCEPT,

	},

	{

		"access skb fields bad1",

		.insns = {

			BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_1, -4),

			BPF_EXIT_INSN(),

		},

		.errstr = "invalid bpf_context access",

		.result = REJECT,

	},

	{

		"access skb fields bad2",

		.insns = {

			BPF_JMP_IMM(BPF_JGE, BPF_REG_1, 0, 9),

			BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0),

			BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),

			BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),

			BPF_LD_MAP_FD(BPF_REG_1, 0),

			BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),

			BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 1),

			BPF_EXIT_INSN(),

			BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),

			BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_1,

				    offsetof(struct __sk_buff, pkt_type)),

			BPF_EXIT_INSN(),

		},

		.fixup = {4},

		.errstr = "different pointers",

		.result = REJECT,

	},

	{

		"access skb fields bad3",

		.insns = {

			BPF_JMP_IMM(BPF_JGE, BPF_REG_1, 0, 2),

			BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_1,

				    offsetof(struct __sk_buff, pkt_type)),

			BPF_EXIT_INSN(),

			BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0),

			BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),

			BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),

			BPF_LD_MAP_FD(BPF_REG_1, 0),

			BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),

			BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 1),

			BPF_EXIT_INSN(),

			BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),

			BPF_JMP_IMM(BPF_JA, 0, 0, -12),

		},

		.fixup = {6},

		.errstr = "different pointers",

		.result = REJECT,

	},

};



static int probe_filter_length(struct bpf_insn *fp)