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borkmann
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davem330
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bpf: add sample usages for persistent maps/progs
This patch adds a couple of stand-alone examples on how BPF_OBJ_PIN and BPF_OBJ_GET commands can be used. Example with maps: # ./fds_example -F /sys/fs/bpf/m -P -m -k 1 -v 42 bpf: map fd:3 (Success) bpf: pin ret:(0,Success) bpf: fd:3 u->(1:42) ret:(0,Success) # ./fds_example -F /sys/fs/bpf/m -G -m -k 1 bpf: get fd:3 (Success) bpf: fd:3 l->(1):42 ret:(0,Success) # ./fds_example -F /sys/fs/bpf/m -G -m -k 1 -v 24 bpf: get fd:3 (Success) bpf: fd:3 u->(1:24) ret:(0,Success) # ./fds_example -F /sys/fs/bpf/m -G -m -k 1 bpf: get fd:3 (Success) bpf: fd:3 l->(1):24 ret:(0,Success) # ./fds_example -F /sys/fs/bpf/m2 -P -m bpf: map fd:3 (Success) bpf: pin ret:(0,Success) # ./fds_example -F /sys/fs/bpf/m2 -G -m -k 1 bpf: get fd:3 (Success) bpf: fd:3 l->(1):0 ret:(0,Success) # ./fds_example -F /sys/fs/bpf/m2 -G -m bpf: get fd:3 (Success) Example with progs: # ./fds_example -F /sys/fs/bpf/p -P -p bpf: prog fd:3 (Success) bpf: pin ret:(0,Success) bpf sock:4 <- fd:3 attached ret:(0,Success) # ./fds_example -F /sys/fs/bpf/p -G -p bpf: get fd:3 (Success) bpf: sock:4 <- fd:3 attached ret:(0,Success) # ./fds_example -F /sys/fs/bpf/p2 -P -p -o ./sockex1_kern.o bpf: prog fd:5 (Success) bpf: pin ret:(0,Success) bpf: sock:3 <- fd:5 attached ret:(0,Success) # ./fds_example -F /sys/fs/bpf/p2 -G -p bpf: get fd:3 (Success) bpf: sock:4 <- fd:3 attached ret:(0,Success) Signed-off-by: Daniel Borkmann <[email protected]> Acked-by: Alexei Starovoitov <[email protected]> Signed-off-by: David S. Miller <[email protected]>
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‎samples/bpf/Makefile

Lines changed: 3 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -4,6 +4,7 @@ obj- := dummy.o
44
# List of programs to build
55
hostprogs-y := test_verifier test_maps
66
hostprogs-y += sock_example
7+
hostprogs-y += fds_example
78
hostprogs-y += sockex1
89
hostprogs-y += sockex2
910
hostprogs-y += sockex3
@@ -19,6 +20,7 @@ hostprogs-y += lathist
1920
test_verifier-objs := test_verifier.o libbpf.o
2021
test_maps-objs := test_maps.o libbpf.o
2122
sock_example-objs := sock_example.o libbpf.o
23+
fds_example-objs := bpf_load.o libbpf.o fds_example.o
2224
sockex1-objs := bpf_load.o libbpf.o sockex1_user.o
2325
sockex2-objs := bpf_load.o libbpf.o sockex2_user.o
2426
sockex3-objs := bpf_load.o libbpf.o sockex3_user.o
@@ -49,6 +51,7 @@ always += lathist_kern.o
4951
HOSTCFLAGS += -I$(objtree)/usr/include
5052

5153
HOSTCFLAGS_bpf_load.o += -I$(objtree)/usr/include -Wno-unused-variable
54+
HOSTLOADLIBES_fds_example += -lelf
5255
HOSTLOADLIBES_sockex1 += -lelf
5356
HOSTLOADLIBES_sockex2 += -lelf
5457
HOSTLOADLIBES_sockex3 += -lelf

‎samples/bpf/fds_example.c

Lines changed: 183 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,183 @@
1+
#include <linux/unistd.h>
2+
#include <linux/bpf.h>
3+
4+
#include <stdio.h>
5+
#include <stdlib.h>
6+
#include <stdint.h>
7+
#include <unistd.h>
8+
#include <string.h>
9+
#include <assert.h>
10+
#include <errno.h>
11+
12+
#include <sys/types.h>
13+
#include <sys/socket.h>
14+
15+
#include "bpf_load.h"
16+
#include "libbpf.h"
17+
18+
#define BPF_F_PIN (1 << 0)
19+
#define BPF_F_GET (1 << 1)
20+
#define BPF_F_PIN_GET (BPF_F_PIN | BPF_F_GET)
21+
22+
#define BPF_F_KEY (1 << 2)
23+
#define BPF_F_VAL (1 << 3)
24+
#define BPF_F_KEY_VAL (BPF_F_KEY | BPF_F_VAL)
25+
26+
#define BPF_M_UNSPEC 0
27+
#define BPF_M_MAP 1
28+
#define BPF_M_PROG 2
29+
30+
static void usage(void)
31+
{
32+
printf("Usage: fds_example [...]\n");
33+
printf(" -F <file> File to pin/get object\n");
34+
printf(" -P |- pin object\n");
35+
printf(" -G `- get object\n");
36+
printf(" -m eBPF map mode\n");
37+
printf(" -k <key> |- map key\n");
38+
printf(" -v <value> `- map value\n");
39+
printf(" -p eBPF prog mode\n");
40+
printf(" -o <object> `- object file\n");
41+
printf(" -h Display this help.\n");
42+
}
43+
44+
static int bpf_map_create(void)
45+
{
46+
return bpf_create_map(BPF_MAP_TYPE_ARRAY, sizeof(uint32_t),
47+
sizeof(uint32_t), 1024);
48+
}
49+
50+
static int bpf_prog_create(const char *object)
51+
{
52+
static const struct bpf_insn insns[] = {
53+
BPF_MOV64_IMM(BPF_REG_0, 1),
54+
BPF_EXIT_INSN(),
55+
};
56+
57+
if (object) {
58+
assert(!load_bpf_file((char *)object));
59+
return prog_fd[0];
60+
} else {
61+
return bpf_prog_load(BPF_PROG_TYPE_SOCKET_FILTER,
62+
insns, sizeof(insns), "GPL", 0);
63+
}
64+
}
65+
66+
static int bpf_do_map(const char *file, uint32_t flags, uint32_t key,
67+
uint32_t value)
68+
{
69+
int fd, ret;
70+
71+
if (flags & BPF_F_PIN) {
72+
fd = bpf_map_create();
73+
printf("bpf: map fd:%d (%s)\n", fd, strerror(errno));
74+
assert(fd > 0);
75+
76+
ret = bpf_obj_pin(fd, file);
77+
printf("bpf: pin ret:(%d,%s)\n", ret, strerror(errno));
78+
assert(ret == 0);
79+
} else {
80+
fd = bpf_obj_get(file);
81+
printf("bpf: get fd:%d (%s)\n", fd, strerror(errno));
82+
assert(fd > 0);
83+
}
84+
85+
if ((flags & BPF_F_KEY_VAL) == BPF_F_KEY_VAL) {
86+
ret = bpf_update_elem(fd, &key, &value, 0);
87+
printf("bpf: fd:%d u->(%u:%u) ret:(%d,%s)\n", fd, key, value,
88+
ret, strerror(errno));
89+
assert(ret == 0);
90+
} else if (flags & BPF_F_KEY) {
91+
ret = bpf_lookup_elem(fd, &key, &value);
92+
printf("bpf: fd:%d l->(%u):%u ret:(%d,%s)\n", fd, key, value,
93+
ret, strerror(errno));
94+
assert(ret == 0);
95+
}
96+
97+
return 0;
98+
}
99+
100+
static int bpf_do_prog(const char *file, uint32_t flags, const char *object)
101+
{
102+
int fd, sock, ret;
103+
104+
if (flags & BPF_F_PIN) {
105+
fd = bpf_prog_create(object);
106+
printf("bpf: prog fd:%d (%s)\n", fd, strerror(errno));
107+
assert(fd > 0);
108+
109+
ret = bpf_obj_pin(fd, file);
110+
printf("bpf: pin ret:(%d,%s)\n", ret, strerror(errno));
111+
assert(ret == 0);
112+
} else {
113+
fd = bpf_obj_get(file);
114+
printf("bpf: get fd:%d (%s)\n", fd, strerror(errno));
115+
assert(fd > 0);
116+
}
117+
118+
sock = open_raw_sock("lo");
119+
assert(sock > 0);
120+
121+
ret = setsockopt(sock, SOL_SOCKET, SO_ATTACH_BPF, &fd, sizeof(fd));
122+
printf("bpf: sock:%d <- fd:%d attached ret:(%d,%s)\n", sock, fd,
123+
ret, strerror(errno));
124+
assert(ret == 0);
125+
126+
return 0;
127+
}
128+
129+
int main(int argc, char **argv)
130+
{
131+
const char *file = NULL, *object = NULL;
132+
uint32_t key = 0, value = 0, flags = 0;
133+
int opt, mode = BPF_M_UNSPEC;
134+
135+
while ((opt = getopt(argc, argv, "F:PGmk:v:po:")) != -1) {
136+
switch (opt) {
137+
/* General args */
138+
case 'F':
139+
file = optarg;
140+
break;
141+
case 'P':
142+
flags |= BPF_F_PIN;
143+
break;
144+
case 'G':
145+
flags |= BPF_F_GET;
146+
break;
147+
/* Map-related args */
148+
case 'm':
149+
mode = BPF_M_MAP;
150+
break;
151+
case 'k':
152+
key = strtoul(optarg, NULL, 0);
153+
flags |= BPF_F_KEY;
154+
break;
155+
case 'v':
156+
value = strtoul(optarg, NULL, 0);
157+
flags |= BPF_F_VAL;
158+
break;
159+
/* Prog-related args */
160+
case 'p':
161+
mode = BPF_M_PROG;
162+
break;
163+
case 'o':
164+
object = optarg;
165+
break;
166+
default:
167+
goto out;
168+
}
169+
}
170+
171+
if (!(flags & BPF_F_PIN_GET) || !file)
172+
goto out;
173+
174+
switch (mode) {
175+
case BPF_M_MAP:
176+
return bpf_do_map(file, flags, key, value);
177+
case BPF_M_PROG:
178+
return bpf_do_prog(file, flags, object);
179+
}
180+
out:
181+
usage();
182+
return -1;
183+
}

‎samples/bpf/libbpf.c

Lines changed: 19 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -103,6 +103,25 @@ int bpf_prog_load(enum bpf_prog_type prog_type,
103103
return syscall(__NR_bpf, BPF_PROG_LOAD, &attr, sizeof(attr));
104104
}
105105

106+
int bpf_obj_pin(int fd, const char *pathname)
107+
{
108+
union bpf_attr attr = {
109+
.pathname = ptr_to_u64((void *)pathname),
110+
.bpf_fd = fd,
111+
};
112+
113+
return syscall(__NR_bpf, BPF_OBJ_PIN, &attr, sizeof(attr));
114+
}
115+
116+
int bpf_obj_get(const char *pathname)
117+
{
118+
union bpf_attr attr = {
119+
.pathname = ptr_to_u64((void *)pathname),
120+
};
121+
122+
return syscall(__NR_bpf, BPF_OBJ_GET, &attr, sizeof(attr));
123+
}
124+
106125
int open_raw_sock(const char *name)
107126
{
108127
struct sockaddr_ll sll;

‎samples/bpf/libbpf.h

Lines changed: 3 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -15,6 +15,9 @@ int bpf_prog_load(enum bpf_prog_type prog_type,
1515
const struct bpf_insn *insns, int insn_len,
1616
const char *license, int kern_version);
1717

18+
int bpf_obj_pin(int fd, const char *pathname);
19+
int bpf_obj_get(const char *pathname);
20+
1821
#define LOG_BUF_SIZE 65536
1922
extern char bpf_log_buf[LOG_BUF_SIZE];
2023

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