[bpf-next,V9,3/3] tools/testing/selftests/bpf: Add self-tests for new helper.

From: Carlos <cneirabustos@gmail.com>

Added self-tests for new helper bpf_get_current_pidns_info.

Signed-off-by: Carlos Neira <cneirabustos@gmail.com>
---
 tools/include/uapi/linux/bpf.h                     |  31 ++++-
 tools/testing/selftests/bpf/Makefile               |   2 +-
 tools/testing/selftests/bpf/bpf_helpers.h          |   3 +
 .../testing/selftests/bpf/progs/test_pidns_kern.c  |  51 ++++++++
 tools/testing/selftests/bpf/test_pidns.c           | 138 +++++++++++++++++++++
 5 files changed, 223 insertions(+), 2 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/progs/test_pidns_kern.c
 create mode 100644 tools/testing/selftests/bpf/test_pidns.c

On 8/13/19 11:47 AM, Carlos Neira wrote:
> From: Carlos <cneirabustos@gmail.com>
> 
> Added self-tests for new helper bpf_get_current_pidns_info.
> 
> Signed-off-by: Carlos Neira <cneirabustos@gmail.com>
> ---
>   tools/include/uapi/linux/bpf.h                     |  31 ++++-
>   tools/testing/selftests/bpf/Makefile               |   2 +-
>   tools/testing/selftests/bpf/bpf_helpers.h          |   3 +
>   .../testing/selftests/bpf/progs/test_pidns_kern.c  |  51 ++++++++
>   tools/testing/selftests/bpf/test_pidns.c           | 138 +++++++++++++++++++++

Could you break this patch into two?
   patch 1: tools/include/uapi/linux/bpf.h
   patch 2: rest of changes

>   5 files changed, 223 insertions(+), 2 deletions(-)
>   create mode 100644 tools/testing/selftests/bpf/progs/test_pidns_kern.c
>   create mode 100644 tools/testing/selftests/bpf/test_pidns.c
> 
> diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
> index 4393bd4b2419..db241857ec15 100644
> --- a/tools/include/uapi/linux/bpf.h
> +++ b/tools/include/uapi/linux/bpf.h
> @@ -2741,6 +2741,28 @@ union bpf_attr {
>    *		**-EOPNOTSUPP** kernel configuration does not enable SYN cookies
>    *
>    *		**-EPROTONOSUPPORT** IP packet version is not 4 or 6
> + *
> + * int bpf_get_current_pidns_info(struct bpf_pidns_info *pidns, u32 size_of_pidns)
> + *	Description
> + *		Copies into *pidns* pid, namespace id and tgid as seen by the
> + *		current namespace and also device from /proc/self/ns/pid.
> + *		*size_of_pidns* must be the size of *pidns*
> + *
> + *		This helper is used when pid filtering is needed inside a
> + *		container as bpf_get_current_tgid() helper returns always the
> + *		pid id as seen by the root namespace.
> + *	Return
> + *		0 on success
> + *
> + *		**-EINVAL** if *size_of_pidns* is not valid or unable to get ns, pid
> + *		or tgid of the current task.
> + *
> + *		**-ECHILD** if /proc/self/ns/pid does not exists.
> + *
> + *		**-ENOTDIR** if /proc/self/ns does not exists.
> + *
> + *		**-ENOMEM**  if allocation fails.
> + *
>    */
>   #define __BPF_FUNC_MAPPER(FN)		\
>   	FN(unspec),			\
> @@ -2853,7 +2875,8 @@ union bpf_attr {
>   	FN(sk_storage_get),		\
>   	FN(sk_storage_delete),		\
>   	FN(send_signal),		\
> -	FN(tcp_gen_syncookie),
> +	FN(tcp_gen_syncookie),		\
> +	FN(get_current_pidns_info),
>   
>   /* integer value in 'imm' field of BPF_CALL instruction selects which helper
>    * function eBPF program intends to call
> @@ -3604,4 +3627,10 @@ struct bpf_sockopt {
>   	__s32	retval;
>   };
>   
> +struct bpf_pidns_info {
> +	__u32 dev;
> +	__u32 nsid;
> +	__u32 tgid;
> +	__u32 pid;
> +};
>   #endif /* _UAPI__LINUX_BPF_H__ */
> diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
> index 3bd0f4a0336a..1f97b571b581 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_tcp_rtt
> +	test_sockopt_multi test_tcp_rtt test_pidns
>   
>   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 8b503ea142f0..3fae3b9fcd2c 100644
> --- a/tools/testing/selftests/bpf/bpf_helpers.h
> +++ b/tools/testing/selftests/bpf/bpf_helpers.h
> @@ -231,6 +231,9 @@ static int (*bpf_send_signal)(unsigned sig) = (void *)BPF_FUNC_send_signal;
>   static long long (*bpf_tcp_gen_syncookie)(struct bpf_sock *sk, void *ip,
>   					  int ip_len, void *tcp, int tcp_len) =
>   	(void *) BPF_FUNC_tcp_gen_syncookie;
> +static int (*bpf_get_current_pidns_info)(struct bpf_pidns_info *buf,
> +					 unsigned int buf_size) =
> +	(void *) BPF_FUNC_get_current_pidns_info;
>   
>   /* llvm builtin functions that eBPF C program may use to
>    * emit BPF_LD_ABS and BPF_LD_IND instructions
> 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..e1d2facfa762
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/test_pidns_kern.c
> @@ -0,0 +1,51 @@
> +// 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 bpf_map_def SEC("maps") nsidmap = {
> +	.type = BPF_MAP_TYPE_ARRAY,
> +	.key_size = sizeof(__u32),
> +	.value_size = sizeof(__u32),
> +	.max_entries = 1,
> +};
> +
> +struct bpf_map_def SEC("maps") pidmap = {
> +	.type = BPF_MAP_TYPE_ARRAY,
> +	.key_size = sizeof(__u32),
> +	.value_size = sizeof(__u32),
> +	.max_entries = 1,
> +};

Could you use new map definitions. Search
"SEC(".maps")" for examples.

> +
> +SEC("tracepoint/syscalls/sys_enter_nanosleep")
> +int trace(void *ctx)
> +{
> +	struct bpf_pidns_info nsinfo;
> +	__u32 key = 0, *expected_pid, *val;
> +	char fmt[] = "ERROR nspid:%d\n";
> +
> +	if (bpf_get_current_pidns_info(&nsinfo, sizeof(nsinfo)))
> +		return -EINVAL;
> +
> +	expected_pid = bpf_map_lookup_elem(&pidmap, &key);
> +
> +
> +	if (!expected_pid || *expected_pid != nsinfo.pid)
> +		return 0;
> 

I would like you to compare device major/minor, namespace id,
pid and tid. We should test everything here.

+
> +	val = bpf_map_lookup_elem(&nsidmap, &key);
> +	if (val)
> +		*val = nsinfo.nsid;
> +
> +	return 0;
> +}
> +
> +char _license[] SEC("license") = "GPL";
> +__u32 _version SEC("version") = 1;
> diff --git a/tools/testing/selftests/bpf/test_pidns.c b/tools/testing/selftests/bpf/test_pidns.c
> new file mode 100644
> index 000000000000..a7254055f294
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/test_pidns.c
> @@ -0,0 +1,138 @@
> +// 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;
> +	int pidmap_fd, nsidmap_fd;
> +	struct perf_event_attr attr = {};
> +	struct bpf_object *obj;
> +	__u32 knsid = 0;
> +	__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;

Please use libbpf perf APIs.

It would be good if the test actually create a namespace and do the test.

Do you think it is possible to use the existing test_progs 
infrastructure. The current one without creating pid namespace
surely fit in. Not sure if we add creating/deleting namespace,
I would think it should fit in as well.

> +
> +	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 != (__u32) st.st_ino, "compare_namespace_id",
> +		  "kern knsid %u user unsid %u\n", knsid, (__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;
> +}
>