Re: [PATCH bpf-next v10 4/4] tools/testing/selftests/bpf: Add self-tests for helper bpf_get_pidns_info.

[Yonghong Song <yhs@fb.com>]

On 9/6/19 4:09 PM, Carlos Neira wrote:
> Added 2 selftest:
> 
> bpf_get_current_pidns_info helper is called in an interrupt
> context and also in a non interrupt context.
> 
> Signed-off-by: Carlos Neira <cneirabustos@gmail.com>
> ---
>   tools/testing/selftests/bpf/Makefile               |   2 +-
>   tools/testing/selftests/bpf/bpf_helpers.h          |   3 +
>   .../testing/selftests/bpf/progs/test_pidns_kern.c  |  52 ++++++++
>   .../selftests/bpf/progs/test_pidns_nmi_kern.c      |  52 ++++++++
>   tools/testing/selftests/bpf/test_pidns.c           | 146 +++++++++++++++++++++
>   tools/testing/selftests/bpf/test_pidns_nmi.c       | 139 ++++++++++++++++++++
>   6 files changed, 393 insertions(+), 1 deletion(-)
>   create mode 100644 tools/testing/selftests/bpf/progs/test_pidns_kern.c
>   create mode 100644 tools/testing/selftests/bpf/progs/test_pidns_nmi_kern.c
>   create mode 100644 tools/testing/selftests/bpf/test_pidns.c
>   create mode 100644 tools/testing/selftests/bpf/test_pidns_nmi.c
> 
> diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
> index 1faad0c3c3c9..8507c89141f5 100644
> --- a/tools/testing/selftests/bpf/Makefile
> +++ b/tools/testing/selftests/bpf/Makefile
> @@ -29,7 +29,7 @@ TEST_GEN_PROGS = test_verifier test_tag test_maps test_lru_map test_lpm_map test
>   	test_cgroup_storage test_select_reuseport test_section_names \
>   	test_netcnt test_tcpnotify_user test_sock_fields test_sysctl test_hashmap \
>   	test_btf_dump test_cgroup_attach xdping test_sockopt test_sockopt_sk \
> -	test_sockopt_multi test_sockopt_inherit test_tcp_rtt
> +	test_sockopt_multi test_sockopt_inherit test_tcp_rtt test_pidns test_pidns_nmi
>   
>   BPF_OBJ_FILES = $(patsubst %.c,%.o, $(notdir $(wildcard progs/*.c)))
>   TEST_GEN_FILES = $(BPF_OBJ_FILES)
> diff --git a/tools/testing/selftests/bpf/bpf_helpers.h b/tools/testing/selftests/bpf/bpf_helpers.h
> index 6c4930bc6e2e..30a70ebe583a 100644
> --- a/tools/testing/selftests/bpf/bpf_helpers.h
> +++ b/tools/testing/selftests/bpf/bpf_helpers.h
> @@ -313,6 +313,9 @@ static unsigned int (*bpf_set_hash)(void *ctx, __u32 hash) =
>   static int (*bpf_skb_adjust_room)(void *ctx, __s32 len_diff, __u32 mode,
>   				  unsigned long long flags) =
>   	(void *) BPF_FUNC_skb_adjust_room;
> +static int (*bpf_get_current_pidns_info)(struct bpf_pidns_info *buf,
> +					 unsigned int buf_size) =
> +	(void *) BPF_FUNC_get_current_pidns_info;
>   
>   /* Scan the ARCH passed in from ARCH env variable (see Makefile) */
>   #if defined(__TARGET_ARCH_x86)
> diff --git a/tools/testing/selftests/bpf/progs/test_pidns_kern.c b/tools/testing/selftests/bpf/progs/test_pidns_kern.c
> new file mode 100644
> index 000000000000..a4c0bde1608b
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/test_pidns_kern.c
> @@ -0,0 +1,52 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/* Copyright (c) 2018 Carlos Neira cneirabustos@gmail.com
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of version 2 of the GNU General Public
> + * License as published by the Free Software Foundation.
> + */
> +
> +#include <linux/bpf.h>
> +#include <errno.h>
> +#include "bpf_helpers.h"
> +
> +struct {
> +	__uint(type, BPF_MAP_TYPE_ARRAY);
> +	__uint(max_entries, 1);
> +	__type(key, __u32);
> +	__type(value, struct bpf_pidns_info);
> +} nsidmap SEC(".maps");
> +
> +struct {
> +	__uint(type, BPF_MAP_TYPE_ARRAY);
> +	__uint(max_entries, 1);
> +	__type(key, __u32);
> +	__type(value, __u32);
> +} pidmap SEC(".maps");
> +
> +SEC("tracepoint/syscalls/sys_enter_nanosleep")
> +int trace(void *ctx)
> +{
> +	struct bpf_pidns_info nsinfo;
> +	__u32 key = 0, *expected_pid;
> +	struct bpf_pidns_info  *val;
> +
> +	if (bpf_get_current_pidns_info(&nsinfo, sizeof(nsinfo)))
> +		return -EINVAL;
> +
> +	expected_pid = bpf_map_lookup_elem(&pidmap, &key);
> +	__u64 tgid = bpf_get_current_pid_tgid();
> +
> +	if (!expected_pid || *expected_pid != nsinfo.pid ||
> +			nsinfo.tgid != (__u32)tgid)
> +		return 0;

The logic in the above is not right.
bpf_get_current_pidns_info() retrieved
   dev, nsid, tgid and pid.

You should create a map, populate dev/nsid you
got from the user space. And then update maybe
another map with tgid/pid and passed back to
user space for verification.

> +
> +	val = bpf_map_lookup_elem(&nsidmap, &key);
> +	if (val)
> +		*val = nsinfo;
> +
> +	return 0;
> +}
> +
> +char _license[] SEC("license") = "GPL";
> +__u32 _version SEC("version") = 1;
> diff --git a/tools/testing/selftests/bpf/progs/test_pidns_nmi_kern.c b/tools/testing/selftests/bpf/progs/test_pidns_nmi_kern.c
> new file mode 100644
> index 000000000000..7f02e4e29021
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/test_pidns_nmi_kern.c
> @@ -0,0 +1,52 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/* Copyright (c) 2018 Carlos Neira cneirabustos@gmail.com
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of version 2 of the GNU General Public
> + * License as published by the Free Software Foundation.
> + */
> +
> +#include <linux/bpf.h>
> +#include <errno.h>
> +#include "bpf_helpers.h"
> +
> +struct {
> +	__uint(type, BPF_MAP_TYPE_ARRAY);
> +	__uint(max_entries, 1);
> +	__type(key, __u32);
> +	__type(value, struct bpf_pidns_info);
> +} nsidmap SEC(".maps");
> +
> +struct {
> +	__uint(type, BPF_MAP_TYPE_ARRAY);
> +	__uint(max_entries, 1);
> +	__type(key, __u32);
> +	__type(value, __u32);
> +} pidmap SEC(".maps");
> +
> +SEC("tracepoint/net/netif_receive_skb")
> +int trace(void *ctx)
> +{
> +	struct bpf_pidns_info nsinfo;
> +	__u32 key = 0, *expected_pid;
> +	struct bpf_pidns_info  *val;
> +
> +	if (bpf_get_current_pidns_info(&nsinfo, sizeof(nsinfo)))
> +		return -EINVAL;
> +
> +	expected_pid = bpf_map_lookup_elem(&pidmap, &key);
> +	__u64 tgid = bpf_get_current_pid_tgid();
> +
> +	if (!expected_pid || *expected_pid != nsinfo.pid ||
> +			nsinfo.tgid != (__u32)tgid)
> +		return 0;
> +
> +	val = bpf_map_lookup_elem(&nsidmap, &key);
> +	if (val)
> +		*val = nsinfo;
> +
> +	return 0;
> +}
> +
> +char _license[] SEC("license") = "GPL";
> +__u32 _version SEC("version") = 1;

With the new nsfs interface function(), the file test_pidns_nmi_kern.c
is not needed any more.

Please also remove the in_interrupt() checking in the kernel helper 
implementation.

> diff --git a/tools/testing/selftests/bpf/test_pidns.c b/tools/testing/selftests/bpf/test_pidns.c

Please restructure and put this file under 
tools/testing/selftests/bpf/prog_tests directory.

> new file mode 100644
> index 000000000000..0c579305da53
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/test_pidns.c
> @@ -0,0 +1,146 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/* Copyright (c) 2018 Carlos Neira cneirabustos@gmail.com
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of version 2 of the GNU General Public
> + * License as published by the Free Software Foundation.
> + */
> +
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <errno.h>
> +#include <fcntl.h>
> +#include <syscall.h>
> +#include <unistd.h>
> +#include <linux/perf_event.h>
> +#include <sys/ioctl.h>
> +#include <sys/time.h>
> +#include <sys/types.h>
> +#include <sys/stat.h>
> +
> +#include <linux/bpf.h>
> +#include <bpf/bpf.h>
> +#include <bpf/libbpf.h>
> +
> +#include "cgroup_helpers.h"
> +#include "bpf_rlimit.h"
> +
> +#define CHECK(condition, tag, format...) ({		\
> +	int __ret = !!(condition);			\
> +	if (__ret) {					\
> +		printf("%s:FAIL:%s ", __func__, tag);	\
> +		printf(format);				\
> +	} else {					\
> +		printf("%s:PASS:%s\n", __func__, tag);	\
> +	}						\
> +	__ret;						\
> +})
> +
> +static int bpf_find_map(const char *test, struct bpf_object *obj,
> +			const char *name)
> +{
> +	struct bpf_map *map;
> +
> +	map = bpf_object__find_map_by_name(obj, name);
> +	if (!map)
> +		return -1;
> +	return bpf_map__fd(map);
> +}
> +
> +
> +int main(int argc, char **argv)
> +{
> +	const char *probe_name = "syscalls/sys_enter_nanosleep";
> +	const char *file = "test_pidns_kern.o";
> +	int err, bytes, efd, prog_fd, pmu_fd;
> +	struct bpf_pidns_info knsid = {};
> +	int pidmap_fd, nsidmap_fd;
> +	struct perf_event_attr attr = {};
> +	struct bpf_object *obj;
> +	__u32 key = 0, pid;
> +	int exit_code = 1;
> +	struct stat st;
> +	char buf[256];
> +
> +	err = bpf_prog_load(file, BPF_PROG_TYPE_TRACEPOINT, &obj, &prog_fd);
> +	if (CHECK(err, "bpf_prog_load", "err %d errno %d\n", err, errno))
> +		goto cleanup_cgroup_env;
> +
> +	nsidmap_fd = bpf_find_map(__func__, obj, "nsidmap");
> +	if (CHECK(nsidmap_fd < 0, "bpf_find_map", "err %d errno %d\n",
> +		  nsidmap_fd, errno))
> +		goto close_prog;
> +
> +	pidmap_fd = bpf_find_map(__func__, obj, "pidmap");
> +	if (CHECK(pidmap_fd < 0, "bpf_find_map", "err %d errno %d\n",
> +		  pidmap_fd, errno))
> +		goto close_prog;
> +
> +	pid = getpid();
> +	bpf_map_update_elem(pidmap_fd, &key, &pid, 0);
> +
> +	snprintf(buf, sizeof(buf),
> +		 "/sys/kernel/debug/tracing/events/%s/id", probe_name);
> +	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;
> +
> +	attr.config = strtol(buf, NULL, 0);
> +	attr.type = PERF_TYPE_TRACEPOINT;
> +	attr.sample_type = PERF_SAMPLE_RAW;
> +	attr.sample_period = 1;
> +	attr.wakeup_events = 1;
> +
> +	pmu_fd = syscall(__NR_perf_event_open, &attr, getpid(), -1, -1, 0);
> +	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 close_pmu;
> +
> +	/* trigger some syscalls */
> +	sleep(1);
> +
> +	err = bpf_map_lookup_elem(nsidmap_fd, &key, &knsid);
> +	if (CHECK(err, "bpf_map_lookup_elem", "err %d errno %d\n", err, errno))
> +		goto close_pmu;
> +
> +	if (stat("/proc/self/ns/pid", &st))
> +		goto close_pmu;
> +
> +	if (CHECK(knsid.nsid != (__u32) st.st_ino, "namespace id",
> +		  "bpf %u user %u\n", knsid.nsid, (__u32) st.st_ino))
> +		goto close_pmu;
> +
> +	if (CHECK(major(knsid.dev) != major(st.st_rdev), "dev major",
> +		  "bpf %u user %u\n", major(knsid.dev), major(st.st_rdev)))
> +		goto close_pmu;
> +
> +	if (CHECK(minor(knsid.dev) != minor(st.st_rdev), "dev minor",
> +		  "bpf %u user %u\n", minor(knsid.dev), minor(st.st_rdev)))
> +		goto close_pmu;
> +
> +	exit_code = 0;
> +	printf("%s:PASS\n", argv[0]);
> +
> +close_pmu:
> +	close(pmu_fd);
> +close_prog:
> +	bpf_object__close(obj);
> +cleanup_cgroup_env:
> +	return exit_code;
> +}
> diff --git a/tools/testing/selftests/bpf/test_pidns_nmi.c b/tools/testing/selftests/bpf/test_pidns_nmi.c
> new file mode 100644
> index 000000000000..bb8075bbe7d8
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/test_pidns_nmi.c
> @@ -0,0 +1,139 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/* Copyright (c) 2018 Carlos Neira cneirabustos@gmail.com
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of version 2 of the GNU General Public
> + * License as published by the Free Software Foundation.
> + */
> +
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <errno.h>
> +#include <fcntl.h>
> +#include <syscall.h>
> +#include <unistd.h>
> +#include <linux/perf_event.h>
> +#include <sys/ioctl.h>
> +#include <sys/time.h>
> +#include <sys/types.h>
> +#include <sys/stat.h>
> +
> +#include <linux/bpf.h>
> +#include <bpf/bpf.h>
> +#include <bpf/libbpf.h>
> +
> +#include "cgroup_helpers.h"
> +#include "bpf_rlimit.h"
> +
> +#define CHECK(condition, tag, format...) ({		\
> +	int __ret = !!(condition);			\
> +	if (__ret) {					\
> +		printf("%s:FAIL:%s ", __func__, tag);	\
> +		printf(format);				\
> +	} else {					\
> +		printf("%s:PASS:%s\n", __func__, tag);	\
> +	}						\
> +	__ret;						\
> +})
> +
> +static int bpf_find_map(const char *test, struct bpf_object *obj,
> +			const char *name)
> +{
> +	struct bpf_map *map;
> +
> +	map = bpf_object__find_map_by_name(obj, name);
> +	if (!map)
> +		return -1;
> +	return bpf_map__fd(map);
> +}
> +
> +
> +int main(int argc, char **argv)
> +{
> +	const char *probe_name = "net/netif_receive_skb";
> +	const char *file = "test_pidns_kern.o";
> +	int err, bytes, efd, prog_fd, pmu_fd;
> +	struct bpf_pidns_info knsid = {};
> +	int pidmap_fd, nsidmap_fd;
> +	struct perf_event_attr attr = {};
> +	struct bpf_object *obj;
> +	__u32 key = 0, pid;
> +	int exit_code = 1;
> +	struct stat st;
> +	char buf[256];
> +
> +	err = bpf_prog_load(file, BPF_PROG_TYPE_TRACEPOINT, &obj, &prog_fd);
> +	if (CHECK(err, "bpf_prog_load", "err %d errno %d\n", err, errno))
> +		goto cleanup_cgroup_env;
> +
> +	nsidmap_fd = bpf_find_map(__func__, obj, "nsidmap");
> +	if (CHECK(nsidmap_fd < 0, "bpf_find_map", "err %d errno %d\n",
> +		  nsidmap_fd, errno))
> +		goto close_prog;
> +
> +	pidmap_fd = bpf_find_map(__func__, obj, "pidmap");
> +	if (CHECK(pidmap_fd < 0, "bpf_find_map", "err %d errno %d\n",
> +		  pidmap_fd, errno))
> +		goto close_prog;
> +
> +	pid = getpid();
> +	bpf_map_update_elem(pidmap_fd, &key, &pid, 0);
> +
> +	snprintf(buf, sizeof(buf),
> +		 "/sys/kernel/debug/tracing/events/%s/id", probe_name);
> +	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;
> +
> +	attr.config = strtol(buf, NULL, 0);
> +	attr.type = PERF_TYPE_TRACEPOINT;
> +	attr.sample_type = PERF_SAMPLE_RAW;
> +	attr.sample_period = 1;
> +	attr.wakeup_events = 1;
> +
> +	pmu_fd = syscall(__NR_perf_event_open, &attr, getpid(), -1, -1, 0);
> +	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 close_pmu;
> +
> +	/* trigger some syscalls */
> +	sleep(1);
> +
> +	err = bpf_map_lookup_elem(nsidmap_fd, &key, &knsid);
> +	if (CHECK(err, "bpf_map_lookup_elem", "err %d errno %d\n", err, errno))
> +		goto close_pmu;
> +
> +	if (stat("/proc/self/ns/pid", &st))
> +		goto close_pmu;
> +
> +	if (CHECK(knsid.nsid != (__u32) st.st_ino, "namespace_id",
> +				"Called in interrupt context bpf %u user %u\n",
> +				knsid.nsid, (__u32) st.st_ino))
> +		goto close_pmu;
> +
> +	exit_code = 0;
> +	printf("%s:PASS\n", argv[0]);
> +
> +close_pmu:
> +	close(pmu_fd);
> +close_prog:
> +	bpf_object__close(obj);
> +cleanup_cgroup_env:
> +	return exit_code;
> +}

the file test_pidns_nmi.c is not needed any more.