Date:   Sat, 11 Aug 2018 23:58:45 -0700
From:   Yonghong Song <yhs@...com>
To:     Andrey Ignatov <rdna@...com>, <netdev@...r.kernel.org>
CC:     <ast@...nel.org>, <daniel@...earbox.net>, <tj@...nel.org>,
        <guro@...com>, <kernel-team@...com>
Subject: Re: [PATCH bpf-next 4/4] selftests/bpf: Selftest for
 bpf_skb_ancestor_cgroup_id



On 8/10/18 10:35 PM, Andrey Ignatov wrote:
> Add selftests for bpf_skb_ancestor_cgroup_id helper.
> 
> test_skb_cgroup_id.sh prepares testing interface and adds tc qdisc and
> filter for it using BPF object compiled from test_skb_cgroup_id_kern.c
> program.
> 
> BPF program in test_skb_cgroup_id_kern.c gets ancestor cgroup id using
> the new helper at different levels of cgroup hierarchy that skb belongs
> to, including root level and non-existing level, and saves it to the map
> where the key is the level of corresponding cgroup and the value is its
> id.
> 
> To trigger BPF program, user space program test_skb_cgroup_id_user is
> run. It adds itself into testing cgroup and sends UDP datagram to
> link-local multicast address of testing interface. Then it reads cgroup
> ids saved in kernel for different levels from the BPF map and compares
> them with those in user space. They must be equal for every level of
> ancestry.
> 
> Example of run:
>    # ./test_skb_cgroup_id.sh
>    Wait for testing link-local IP to become available ... OK
>    Note: 8 bytes struct bpf_elf_map fixup performed due to size mismatch!
>    [PASS]

I am not able to run the test on my FC27 based VM with the latest 
bpf-next and the patch set.

[yhs@...alhost bpf]$ sudo ./test_skb_cgroup_id.sh
Wait for testing link-local IP to become available .....ERROR: Timeout 
waiting for test IP to become available.
[yhs@...alhost bpf]$

I am able to run test_sock_addr.sh successfully.
$ sudo ./test_sock_addr.sh
Wait for testing IPv4/IPv6 to become available .
.. OK
Test case: bind4: load prog with wrong expected attach type .. [PASS]
Test case: bind4: attach prog with wrong attach type .. [PASS]
...
Test case: sendmsg6: deny call .. [PASS]
Summary: 27 PASSED, 0 FAILED

Maybe some issues in this addr ff02::1%${TEST_IF}?

> 
> Signed-off-by: Andrey Ignatov <rdna@...com>
> ---
>   tools/testing/selftests/bpf/Makefile          |   9 +-
>   .../selftests/bpf/test_skb_cgroup_id.sh       |  61 ++++++
>   .../selftests/bpf/test_skb_cgroup_id_kern.c   |  47 +++++
>   .../selftests/bpf/test_skb_cgroup_id_user.c   | 187 ++++++++++++++++++
>   4 files changed, 301 insertions(+), 3 deletions(-)
>   create mode 100755 tools/testing/selftests/bpf/test_skb_cgroup_id.sh
>   create mode 100644 tools/testing/selftests/bpf/test_skb_cgroup_id_kern.c
>   create mode 100644 tools/testing/selftests/bpf/test_skb_cgroup_id_user.c
> 
> diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
> index daed162043c2..fff7fb1285fc 100644
> --- a/tools/testing/selftests/bpf/Makefile
> +++ b/tools/testing/selftests/bpf/Makefile
> @@ -34,7 +34,8 @@ TEST_GEN_FILES = test_pkt_access.o test_xdp.o test_l4lb.o test_tcp_estats.o test
>   	test_btf_haskv.o test_btf_nokv.o test_sockmap_kern.o test_tunnel_kern.o \
>   	test_get_stack_rawtp.o test_sockmap_kern.o test_sockhash_kern.o \
>   	test_lwt_seg6local.o sendmsg4_prog.o sendmsg6_prog.o test_lirc_mode2_kern.o \
> -	get_cgroup_id_kern.o socket_cookie_prog.o test_select_reuseport_kern.o
> +	get_cgroup_id_kern.o socket_cookie_prog.o test_select_reuseport_kern.o \
> +	test_skb_cgroup_id_kern.o
>   
>   # Order correspond to 'make run_tests' order
>   TEST_PROGS := test_kmod.sh \
> @@ -45,10 +46,11 @@ TEST_PROGS := test_kmod.sh \
>   	test_sock_addr.sh \
>   	test_tunnel.sh \
>   	test_lwt_seg6local.sh \
> -	test_lirc_mode2.sh
> +	test_lirc_mode2.sh \
> +	test_skb_cgroup_id.sh
>   
>   # Compile but not part of 'make run_tests'
> -TEST_GEN_PROGS_EXTENDED = test_libbpf_open test_sock_addr
> +TEST_GEN_PROGS_EXTENDED = test_libbpf_open test_sock_addr test_skb_cgroup_id_user
>   
>   include ../lib.mk
>   
> @@ -59,6 +61,7 @@ $(TEST_GEN_PROGS): $(BPFOBJ)
>   $(TEST_GEN_PROGS_EXTENDED): $(OUTPUT)/libbpf.a
>   
>   $(OUTPUT)/test_dev_cgroup: cgroup_helpers.c
> +$(OUTPUT)/test_skb_cgroup_id_user: cgroup_helpers.c
>   $(OUTPUT)/test_sock: cgroup_helpers.c
>   $(OUTPUT)/test_sock_addr: cgroup_helpers.c
>   $(OUTPUT)/test_socket_cookie: cgroup_helpers.c
> diff --git a/tools/testing/selftests/bpf/test_skb_cgroup_id.sh b/tools/testing/selftests/bpf/test_skb_cgroup_id.sh
> new file mode 100755
> index 000000000000..b75e9b52f06f
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/test_skb_cgroup_id.sh
> @@ -0,0 +1,61 @@
> +#!/bin/sh
> +# SPDX-License-Identifier: GPL-2.0
> +# Copyright (c) 2018 Facebook
> +
> +set -eu
> +
> +wait_for_ip()
> +{
> +	local _i
> +	echo -n "Wait for testing link-local IP to become available "
> +	for _i in $(seq ${MAX_PING_TRIES}); do
> +		echo -n "."
> +		if ping -6 -q -c 1 -W 1 ff02::1%${TEST_IF} >/dev/null 2>&1; then
> +			echo " OK"
> +			return
> +		fi
> +	done
> +	echo 1>&2 "ERROR: Timeout waiting for test IP to become available."
> +	exit 1
> +}
> +
> +setup()
> +{
> +	# Create testing interfaces not to interfere with current environment.
> +	ip link add dev ${TEST_IF} type veth peer name ${TEST_IF_PEER}
> +	ip link set ${TEST_IF} up
> +	ip link set ${TEST_IF_PEER} up
> +
> +	wait_for_ip
> +
> +	tc qdisc add dev ${TEST_IF} clsact
> +	tc filter add dev ${TEST_IF} egress bpf obj ${BPF_PROG_OBJ} \
> +		sec ${BPF_PROG_SECTION} da
> +
> +	BPF_PROG_ID=$(tc filter show dev ${TEST_IF} egress | \
> +			awk '/ id / {sub(/.* id /, "", $0); print($1)}')
> +}
> +
> +cleanup()
> +{
> +	ip link del ${TEST_IF} 2>/dev/null || :
> +	ip link del ${TEST_IF_PEER} 2>/dev/null || :
> +}
> +
> +main()
> +{
> +	trap cleanup EXIT 2 3 6 15
> +	setup
> +	${PROG} ${TEST_IF} ${BPF_PROG_ID}
> +}
> +
> +DIR=$(dirname $0)
> +TEST_IF="test_cgid_1"
> +TEST_IF_PEER="test_cgid_2"
> +MAX_PING_TRIES=5
> +BPF_PROG_OBJ="${DIR}/test_skb_cgroup_id_kern.o"
> +BPF_PROG_SECTION="cgroup_id_logger"
> +BPF_PROG_ID=0
> +PROG="${DIR}/test_skb_cgroup_id_user"
> +
> +main
> diff --git a/tools/testing/selftests/bpf/test_skb_cgroup_id_kern.c b/tools/testing/selftests/bpf/test_skb_cgroup_id_kern.c
> new file mode 100644
> index 000000000000..68cf9829f5a7
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/test_skb_cgroup_id_kern.c
> @@ -0,0 +1,47 @@
> +// SPDX-License-Identifier: GPL-2.0
> +// Copyright (c) 2018 Facebook
> +
> +#include <linux/bpf.h>
> +#include <linux/pkt_cls.h>
> +
> +#include <string.h>
> +
> +#include "bpf_helpers.h"
> +
> +#define NUM_CGROUP_LEVELS	4
> +
> +struct bpf_map_def SEC("maps") cgroup_ids = {
> +	.type = BPF_MAP_TYPE_ARRAY,
> +	.key_size = sizeof(__u32),
> +	.value_size = sizeof(__u64),
> +	.max_entries = NUM_CGROUP_LEVELS,
> +};
> +
> +static __always_inline void log_nth_level(struct __sk_buff *skb, __u32 level)
> +{
> +	__u64 id;
> +
> +	/* [1] &level passed to external function that may change it, it's
> +	 *     incompatible with loop unroll.
> +	 */
> +	id = bpf_skb_ancestor_cgroup_id(skb, level);
> +	bpf_map_update_elem(&cgroup_ids, &level, &id, 0);
> +}
> +
> +SEC("cgroup_id_logger")
> +int log_cgroup_id(struct __sk_buff *skb)
> +{
> +	/* Loop unroll can't be used here due to [1]. Unrolling manually.
> +	 * Number of calls should be in sync with NUM_CGROUP_LEVELS.
> +	 */
> +	log_nth_level(skb, 0);
> +	log_nth_level(skb, 1);
> +	log_nth_level(skb, 2);
> +	log_nth_level(skb, 3);
> +
> +	return TC_ACT_OK;
> +}
> +
> +int _version SEC("version") = 1;
> +
> +char _license[] SEC("license") = "GPL";
> diff --git a/tools/testing/selftests/bpf/test_skb_cgroup_id_user.c b/tools/testing/selftests/bpf/test_skb_cgroup_id_user.c
> new file mode 100644
> index 000000000000..c121cc59f314
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/test_skb_cgroup_id_user.c
> @@ -0,0 +1,187 @@
> +// SPDX-License-Identifier: GPL-2.0
> +// Copyright (c) 2018 Facebook
> +
> +#include <stdlib.h>
> +#include <string.h>
> +#include <unistd.h>
> +
> +#include <arpa/inet.h>
> +#include <net/if.h>
> +#include <netinet/in.h>
> +#include <sys/socket.h>
> +#include <sys/types.h>
> +
> +
> +#include <bpf/bpf.h>
> +#include <bpf/libbpf.h>
> +
> +#include "bpf_rlimit.h"
> +#include "cgroup_helpers.h"
> +
> +#define CGROUP_PATH		"/skb_cgroup_test"
> +#define NUM_CGROUP_LEVELS	4
> +
> +/* RFC 4291, Section 2.7.1 */
> +#define LINKLOCAL_MULTICAST	"ff02::1"
> +
> +static int mk_dst_addr(const char *ip, const char *iface,
> +		       struct sockaddr_in6 *dst)
> +{
> +	memset(dst, 0, sizeof(*dst));
> +
> +	dst->sin6_family = AF_INET6;
> +	dst->sin6_port = htons(1025);
> +
> +	if (inet_pton(AF_INET6, ip, &dst->sin6_addr) != 1) {
> +		log_err("Invalid IPv6: %s", ip);
> +		return -1;
> +	}
> +
> +	dst->sin6_scope_id = if_nametoindex(iface);
> +	if (!dst->sin6_scope_id) {
> +		log_err("Failed to get index of iface: %s", iface);
> +		return -1;
> +	}
> +
> +	return 0;
> +}
> +
> +static int send_packet(const char *iface)
> +{
> +	struct sockaddr_in6 dst;
> +	char msg[] = "msg";
> +	int err = 0;
> +	int fd = -1;
> +
> +	if (mk_dst_addr(LINKLOCAL_MULTICAST, iface, &dst))
> +		goto err;
> +
> +	fd = socket(AF_INET6, SOCK_DGRAM, 0);
> +	if (fd == -1) {
> +		log_err("Failed to create UDP socket");
> +		goto err;
> +	}
> +
> +	if (sendto(fd, &msg, sizeof(msg), 0, (const struct sockaddr *)&dst,
> +		   sizeof(dst)) == -1) {
> +		log_err("Failed to send datagram");
> +		goto err;
> +	}
> +
> +	goto out;
> +err:
> +	err = -1;
> +out:
> +	if (fd >= 0)
> +		close(fd);
> +	return err;
> +}
> +
> +int get_map_fd_by_prog_id(int prog_id)
> +{
> +	struct bpf_prog_info info = {};
> +	__u32 info_len = sizeof(info);
> +	__u32 map_ids[1];
> +	int prog_fd = -1;
> +	int map_fd = -1;
> +
> +	prog_fd = bpf_prog_get_fd_by_id(prog_id);
> +	if (prog_fd < 0) {
> +		log_err("Failed to get fd by prog id %d", prog_id);
> +		goto err;
> +	}
> +
> +	info.nr_map_ids = 1;
> +	info.map_ids = (__u64) (unsigned long) map_ids;
> +
> +	if (bpf_obj_get_info_by_fd(prog_fd, &info, &info_len)) {
> +		log_err("Failed to get info by prog fd %d", prog_fd);
> +		goto err;
> +	}
> +
> +	if (!info.nr_map_ids) {
> +		log_err("No maps found for prog fd %d", prog_fd);
> +		goto err;
> +	}
> +
> +	map_fd = bpf_map_get_fd_by_id(map_ids[0]);
> +	if (map_fd < 0)
> +		log_err("Failed to get fd by map id %d", map_ids[0]);
> +err:
> +	if (prog_fd >= 0)
> +		close(prog_fd);
> +	return map_fd;
> +}
> +
> +int check_ancestor_cgroup_ids(int prog_id)
> +{
> +	__u64 actual_ids[NUM_CGROUP_LEVELS], expected_ids[NUM_CGROUP_LEVELS];
> +	__u32 level;
> +	int err = 0;
> +	int map_fd;
> +
> +	expected_ids[0] = 0x100000001;	/* root cgroup */
> +	expected_ids[1] = get_cgroup_id("");
> +	expected_ids[2] = get_cgroup_id(CGROUP_PATH);
> +	expected_ids[3] = 0; /* non-existent cgroup */
> +
> +	map_fd = get_map_fd_by_prog_id(prog_id);
> +	if (map_fd < 0)
> +		goto err;
> +
> +	for (level = 0; level < NUM_CGROUP_LEVELS; ++level) {
> +		if (bpf_map_lookup_elem(map_fd, &level, &actual_ids[level])) {
> +			log_err("Failed to lookup key %d", level);
> +			goto err;
> +		}
> +		if (actual_ids[level] != expected_ids[level]) {
> +			log_err("%llx (actual) != %llx (expected), level: %u\n",
> +				actual_ids[level], expected_ids[level], level);
> +			goto err;
> +		}
> +	}
> +
> +	goto out;
> +err:
> +	err = -1;
> +out:
> +	if (map_fd >= 0)
> +		close(map_fd);
> +	return err;
> +}
> +
> +int main(int argc, char **argv)
> +{
> +	int cgfd = -1;
> +	int err = 0;
> +
> +	if (argc < 3) {
> +		fprintf(stderr, "Usage: %s iface prog_id\n", argv[0]);
> +		exit(EXIT_FAILURE);
> +	}
> +
> +	if (setup_cgroup_environment())
> +		goto err;
> +
> +	cgfd = create_and_get_cgroup(CGROUP_PATH);
> +	if (!cgfd)
> +		goto err;
> +
> +	if (join_cgroup(CGROUP_PATH))
> +		goto err;
> +
> +	if (send_packet(argv[1]))
> +		goto err;
> +
> +	if (check_ancestor_cgroup_ids(atoi(argv[2])))
> +		goto err;
> +
> +	goto out;
> +err:
> +	err = -1;
> +out:
> +	close(cgfd);
> +	cleanup_cgroup_environment();
> +	printf("[%s]\n", err ? "FAIL" : "PASS");
> +	return err;
> +}
> 

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