Commit 81f77fd0 authored by Song Liu's avatar Song Liu Committed by Daniel Borkmann

bpf: add selftest for stackmap with BPF_F_STACK_BUILD_ID

test_stacktrace_build_id() is added. It accesses tracepoint urandom_read
with "dd" and "urandom_read" and gathers stack traces. Then it reads the
stack traces from the stackmap.

urandom_read is a statically link binary that reads from /dev/urandom.
test_stacktrace_build_id() calls readelf to read build ID of urandom_read
and compares it with build ID from the stackmap.
Signed-off-by: default avatarSong Liu <songliubraving@fb.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
parent 615755a7
......@@ -231,6 +231,28 @@ enum bpf_attach_type {
#define BPF_F_RDONLY (1U << 3)
#define BPF_F_WRONLY (1U << 4)
/* Flag for stack_map, store build_id+offset instead of pointer */
#define BPF_F_STACK_BUILD_ID (1U << 5)
enum bpf_stack_build_id_status {
/* user space need an empty entry to identify end of a trace */
BPF_STACK_BUILD_ID_EMPTY = 0,
/* with valid build_id and offset */
BPF_STACK_BUILD_ID_VALID = 1,
/* couldn't get build_id, fallback to ip */
BPF_STACK_BUILD_ID_IP = 2,
};
#define BPF_BUILD_ID_SIZE 20
struct bpf_stack_build_id {
__s32 status;
unsigned char build_id[BPF_BUILD_ID_SIZE];
union {
__u64 offset;
__u64 ip;
};
};
union bpf_attr {
struct { /* anonymous struct used by BPF_MAP_CREATE command */
__u32 map_type; /* one of enum bpf_map_type */
......
......@@ -13,6 +13,14 @@ endif
CFLAGS += -Wall -O2 -I$(APIDIR) -I$(LIBDIR) -I$(GENDIR) $(GENFLAGS) -I../../../include
LDLIBS += -lcap -lelf -lrt -lpthread
TEST_CUSTOM_PROGS = $(OUTPUT)/urandom_read
all: $(TEST_CUSTOM_PROGS)
$(TEST_CUSTOM_PROGS): urandom_read
urandom_read: urandom_read.c
$(CC) -o $(TEST_CUSTOM_PROGS) -static $<
# Order correspond to 'make run_tests' order
TEST_GEN_PROGS = test_verifier test_tag test_maps test_lru_map test_lpm_map test_progs \
test_align test_verifier_log test_dev_cgroup test_tcpbpf_user
......@@ -21,7 +29,7 @@ TEST_GEN_FILES = test_pkt_access.o test_xdp.o test_l4lb.o test_tcp_estats.o test
test_pkt_md_access.o test_xdp_redirect.o test_xdp_meta.o sockmap_parse_prog.o \
sockmap_verdict_prog.o dev_cgroup.o sample_ret0.o test_tracepoint.o \
test_l4lb_noinline.o test_xdp_noinline.o test_stacktrace_map.o \
sample_map_ret0.o test_tcpbpf_kern.o
sample_map_ret0.o test_tcpbpf_kern.o test_stacktrace_build_id.o
# Order correspond to 'make run_tests' order
TEST_PROGS := test_kmod.sh \
......@@ -74,3 +82,5 @@ $(OUTPUT)/%.o: %.c
$(CLANG) $(CLANG_FLAGS) \
-O2 -target bpf -emit-llvm -c $< -o - | \
$(LLC) -march=bpf -mcpu=$(CPU) -filetype=obj -o $@
EXTRA_CLEAN := $(TEST_CUSTOM_PROGS)
......@@ -841,7 +841,8 @@ static void test_tp_attach_query(void)
static int compare_map_keys(int map1_fd, int map2_fd)
{
__u32 key, next_key;
char val_buf[PERF_MAX_STACK_DEPTH * sizeof(__u64)];
char val_buf[PERF_MAX_STACK_DEPTH *
sizeof(struct bpf_stack_build_id)];
int err;
err = bpf_map_get_next_key(map1_fd, NULL, &key);
......@@ -964,6 +965,166 @@ static void test_stacktrace_map()
return;
}
static int extract_build_id(char *build_id, size_t size)
{
FILE *fp;
char *line = NULL;
size_t len = 0;
fp = popen("readelf -n ./urandom_read | grep 'Build ID'", "r");
if (fp == NULL)
return -1;
if (getline(&line, &len, fp) == -1)
goto err;
fclose(fp);
if (len > size)
len = size;
memcpy(build_id, line, len);
build_id[len] = '\0';
return 0;
err:
fclose(fp);
return -1;
}
static void test_stacktrace_build_id(void)
{
int control_map_fd, stackid_hmap_fd, stackmap_fd;
const char *file = "./test_stacktrace_build_id.o";
int bytes, efd, err, pmu_fd, prog_fd;
struct perf_event_attr attr = {};
__u32 key, previous_key, val, duration = 0;
struct bpf_object *obj;
char buf[256];
int i, j;
struct bpf_stack_build_id id_offs[PERF_MAX_STACK_DEPTH];
int build_id_matches = 0;
err = bpf_prog_load(file, BPF_PROG_TYPE_TRACEPOINT, &obj, &prog_fd);
if (CHECK(err, "prog_load", "err %d errno %d\n", err, errno))
goto out;
/* Get the ID for the sched/sched_switch tracepoint */
snprintf(buf, sizeof(buf),
"/sys/kernel/debug/tracing/events/random/urandom_read/id");
efd = open(buf, O_RDONLY, 0);
if (CHECK(efd < 0, "open", "err %d errno %d\n", efd, errno))
goto close_prog;
bytes = read(efd, buf, sizeof(buf));
close(efd);
if (CHECK(bytes <= 0 || bytes >= sizeof(buf),
"read", "bytes %d errno %d\n", bytes, errno))
goto close_prog;
/* Open the perf event and attach bpf progrram */
attr.config = strtol(buf, NULL, 0);
attr.type = PERF_TYPE_TRACEPOINT;
attr.sample_type = PERF_SAMPLE_RAW | PERF_SAMPLE_CALLCHAIN;
attr.sample_period = 1;
attr.wakeup_events = 1;
pmu_fd = syscall(__NR_perf_event_open, &attr, -1 /* pid */,
0 /* cpu 0 */, -1 /* group id */,
0 /* flags */);
if (CHECK(pmu_fd < 0, "perf_event_open", "err %d errno %d\n",
pmu_fd, errno))
goto close_prog;
err = ioctl(pmu_fd, PERF_EVENT_IOC_ENABLE, 0);
if (CHECK(err, "perf_event_ioc_enable", "err %d errno %d\n",
err, errno))
goto close_pmu;
err = ioctl(pmu_fd, PERF_EVENT_IOC_SET_BPF, prog_fd);
if (CHECK(err, "perf_event_ioc_set_bpf", "err %d errno %d\n",
err, errno))
goto disable_pmu;
/* find map fds */
control_map_fd = bpf_find_map(__func__, obj, "control_map");
if (CHECK(control_map_fd < 0, "bpf_find_map control_map",
"err %d errno %d\n", err, errno))
goto disable_pmu;
stackid_hmap_fd = bpf_find_map(__func__, obj, "stackid_hmap");
if (CHECK(stackid_hmap_fd < 0, "bpf_find_map stackid_hmap",
"err %d errno %d\n", err, errno))
goto disable_pmu;
stackmap_fd = bpf_find_map(__func__, obj, "stackmap");
if (CHECK(stackmap_fd < 0, "bpf_find_map stackmap", "err %d errno %d\n",
err, errno))
goto disable_pmu;
assert(system("dd if=/dev/urandom of=/dev/zero count=4 2> /dev/null")
== 0);
assert(system("./urandom_read if=/dev/urandom of=/dev/zero count=4 2> /dev/null") == 0);
/* disable stack trace collection */
key = 0;
val = 1;
bpf_map_update_elem(control_map_fd, &key, &val, 0);
/* for every element in stackid_hmap, we can find a corresponding one
* in stackmap, and vise versa.
*/
err = compare_map_keys(stackid_hmap_fd, stackmap_fd);
if (CHECK(err, "compare_map_keys stackid_hmap vs. stackmap",
"err %d errno %d\n", err, errno))
goto disable_pmu;
err = compare_map_keys(stackmap_fd, stackid_hmap_fd);
if (CHECK(err, "compare_map_keys stackmap vs. stackid_hmap",
"err %d errno %d\n", err, errno))
goto disable_pmu;
err = extract_build_id(buf, 256);
if (CHECK(err, "get build_id with readelf",
"err %d errno %d\n", err, errno))
goto disable_pmu;
err = bpf_map_get_next_key(stackmap_fd, NULL, &key);
if (CHECK(err, "get_next_key from stackmap",
"err %d, errno %d\n", err, errno))
goto disable_pmu;
do {
char build_id[64];
err = bpf_map_lookup_elem(stackmap_fd, &key, id_offs);
if (CHECK(err, "lookup_elem from stackmap",
"err %d, errno %d\n", err, errno))
goto disable_pmu;
for (i = 0; i < PERF_MAX_STACK_DEPTH; ++i)
if (id_offs[i].status == BPF_STACK_BUILD_ID_VALID &&
id_offs[i].offset != 0) {
for (j = 0; j < 20; ++j)
sprintf(build_id + 2 * j, "%02x",
id_offs[i].build_id[j] & 0xff);
if (strstr(buf, build_id) != NULL)
build_id_matches = 1;
}
previous_key = key;
} while (bpf_map_get_next_key(stackmap_fd, &previous_key, &key) == 0);
CHECK(build_id_matches < 1, "build id match",
"Didn't find expected build ID from the map");
disable_pmu:
ioctl(pmu_fd, PERF_EVENT_IOC_DISABLE);
close_pmu:
close(pmu_fd);
close_prog:
bpf_object__close(obj);
out:
return;
}
int main(void)
{
test_pkt_access();
......@@ -976,6 +1137,7 @@ int main(void)
test_obj_name();
test_tp_attach_query();
test_stacktrace_map();
test_stacktrace_build_id();
printf("Summary: %d PASSED, %d FAILED\n", pass_cnt, error_cnt);
return error_cnt ? EXIT_FAILURE : EXIT_SUCCESS;
......
// SPDX-License-Identifier: GPL-2.0
// Copyright (c) 2018 Facebook
#include <linux/bpf.h>
#include "bpf_helpers.h"
#ifndef PERF_MAX_STACK_DEPTH
#define PERF_MAX_STACK_DEPTH 127
#endif
struct bpf_map_def SEC("maps") control_map = {
.type = BPF_MAP_TYPE_ARRAY,
.key_size = sizeof(__u32),
.value_size = sizeof(__u32),
.max_entries = 1,
};
struct bpf_map_def SEC("maps") stackid_hmap = {
.type = BPF_MAP_TYPE_HASH,
.key_size = sizeof(__u32),
.value_size = sizeof(__u32),
.max_entries = 10000,
};
struct bpf_map_def SEC("maps") stackmap = {
.type = BPF_MAP_TYPE_STACK_TRACE,
.key_size = sizeof(__u32),
.value_size = sizeof(struct bpf_stack_build_id)
* PERF_MAX_STACK_DEPTH,
.max_entries = 128,
.map_flags = BPF_F_STACK_BUILD_ID,
};
/* taken from /sys/kernel/debug/tracing/events/random/urandom_read/format */
struct random_urandom_args {
unsigned long long pad;
int got_bits;
int pool_left;
int input_left;
};
SEC("tracepoint/random/urandom_read")
int oncpu(struct random_urandom_args *args)
{
__u32 key = 0, val = 0, *value_p;
value_p = bpf_map_lookup_elem(&control_map, &key);
if (value_p && *value_p)
return 0; /* skip if non-zero *value_p */
/* The size of stackmap and stackid_hmap should be the same */
key = bpf_get_stackid(args, &stackmap, BPF_F_USER_STACK);
if ((int)key >= 0)
bpf_map_update_elem(&stackid_hmap, &key, &val, 0);
return 0;
}
char _license[] SEC("license") = "GPL";
__u32 _version SEC("version") = 1; /* ignored by tracepoints, required by libbpf.a */
#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdlib.h>
#define BUF_SIZE 256
int main(void)
{
int fd = open("/dev/urandom", O_RDONLY);
int i;
char buf[BUF_SIZE];
if (fd < 0)
return 1;
for (i = 0; i < 4; ++i)
read(fd, buf, BUF_SIZE);
close(fd);
return 0;
}
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