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Message-ID: <CAEf4BzboSWpktGxgYbQCH_GuLqfx2NE2SuR3j0voEN2RiVz_jg@mail.gmail.com>
Date: Wed, 10 Jul 2019 12:25:57 -0700
From: Andrii Nakryiko <andrii.nakryiko@...il.com>
To: Javier Honduvilla Coto <javierhonduco@...com>
Cc: Networking <netdev@...r.kernel.org>, Yonghong Song <yhs@...com>,
Kernel Team <kernel-team@...com>, jonhaslam@...com
Subject: Re: [PATCH v6 bpf-next 3/3] bpf: add tests for bpf_descendant_of
On Wed, Jul 10, 2019 at 11:31 AM Javier Honduvilla Coto
<javierhonduco@...com> wrote:
>
> Adding the following test cases:
FYI, bpf-next is closed, so this won't be able to go in for about 2 weeks.
>
> - bpf_descendant_of(current->pid) == 1
> - bpf_descendant_of(current->real_parent->pid) == 1
> - bpf_descendant_of(1) == 1
> - bpf_descendant_of(0) == 1
>
> - bpf_descendant_of(-1) == 0
> - bpf_descendant_of(current->children[0]->pid) == 0
>
> Signed-off-by: Javier Honduvilla Coto <javierhonduco@...com>
> ---
> tools/testing/selftests/bpf/.gitignore | 1 +
> tools/testing/selftests/bpf/Makefile | 2 +-
> tools/testing/selftests/bpf/bpf_helpers.h | 3 +
> .../bpf/progs/test_descendant_of_kern.c | 43 +++
> .../selftests/bpf/test_descendant_of_user.c | 266 ++++++++++++++++++
> 5 files changed, 314 insertions(+), 1 deletion(-)
> create mode 100644 tools/testing/selftests/bpf/progs/test_descendant_of_kern.c
> create mode 100644 tools/testing/selftests/bpf/test_descendant_of_user.c
>
> diff --git a/tools/testing/selftests/bpf/.gitignore b/tools/testing/selftests/bpf/.gitignore
> index 90f70d2c7c22..4b63d7105ba2 100644
> --- a/tools/testing/selftests/bpf/.gitignore
> +++ b/tools/testing/selftests/bpf/.gitignore
> @@ -43,3 +43,4 @@ test_sockopt
> test_sockopt_sk
> test_sockopt_multi
> test_tcp_rtt
> +test_descendant_of_user
> diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
> index 2620406a53ec..b3dc1e26c41c 100644
> --- a/tools/testing/selftests/bpf/Makefile
> +++ b/tools/testing/selftests/bpf/Makefile
> @@ -27,7 +27,7 @@ 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_descendant_of_user
Could you please instead add this test as part of test_progs? See for
instance prog_tests/attach_probe.c for recently added test.
>
> 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 5a3d92c8bec8..7525783ffbc9 100644
> --- a/tools/testing/selftests/bpf/bpf_helpers.h
> +++ b/tools/testing/selftests/bpf/bpf_helpers.h
> @@ -1,4 +1,6 @@
> /* SPDX-License-Identifier: GPL-2.0 */
> +#include <sys/types.h>
> +
> #ifndef __BPF_HELPERS_H
> #define __BPF_HELPERS_H
>
> @@ -228,6 +230,7 @@ static void *(*bpf_sk_storage_get)(void *map, struct bpf_sock *sk,
> static int (*bpf_sk_storage_delete)(void *map, struct bpf_sock *sk) =
> (void *)BPF_FUNC_sk_storage_delete;
> static int (*bpf_send_signal)(unsigned sig) = (void *)BPF_FUNC_send_signal;
> +static int (*bpf_descendant_of)(pid_t pid) = (void *) BPF_FUNC_descendant_of;
Can you split bpf_helpers.h update into a separate commit?
>
> /* 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_descendant_of_kern.c b/tools/testing/selftests/bpf/progs/test_descendant_of_kern.c
> new file mode 100644
> index 000000000000..802e01595527
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/test_descendant_of_kern.c
> @@ -0,0 +1,43 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +#include <linux/bpf.h>
> +#include "bpf_helpers.h"
> +
> +struct bpf_map_def SEC("maps") pidmap = {
> + .type = BPF_MAP_TYPE_ARRAY,
> + .key_size = sizeof(__u32),
> + .value_size = sizeof(__u32),
> + .max_entries = 2,
> +};
> +
> +struct bpf_map_def SEC("maps") resultmap = {
> + .type = BPF_MAP_TYPE_ARRAY,
> + .key_size = sizeof(__u32),
> + .value_size = sizeof(__u32),
> + .max_entries = 1,
> +};
Please update this to use new BTF-defined maps (see lots of recently
converted tests for example).
> +
> +SEC("tracepoint/syscalls/sys_enter_open")
> +int trace(void *ctx)
> +{
> + __u32 pid = bpf_get_current_pid_tgid();
> + __u32 current_key = 0, ancestor_key = 1, *expected_pid, *ancestor_pid;
> + __u32 *val;
> +
> + expected_pid = bpf_map_lookup_elem(&pidmap, ¤t_key);
> + if (!expected_pid || *expected_pid != pid)
> + return 0;
> +
> + ancestor_pid = bpf_map_lookup_elem(&pidmap, &ancestor_key);
> + if (!ancestor_pid)
> + return 0;
> +
> + val = bpf_map_lookup_elem(&resultmap, ¤t_key);
> + if (val)
> + *val = bpf_descendant_of(*ancestor_pid);
> +
> + return 0;
> +}
> +
> +char _license[] SEC("license") = "GPL";
> +__u32 _version SEC("version") = 1;
> diff --git a/tools/testing/selftests/bpf/test_descendant_of_user.c b/tools/testing/selftests/bpf/test_descendant_of_user.c
> new file mode 100644
> index 000000000000..f616c8c976a4
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/test_descendant_of_user.c
> @@ -0,0 +1,266 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +#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/types.h>
> +#include <sys/wait.h>
> +
> +#include <bpf/bpf.h>
> +#include <bpf/libbpf.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; \
> + })
You won't need this if done as part of test_progs.
> +
> +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_open";
> + const char *file = "test_descendant_of_kern.o";
> + int err, bytes, efd, prog_fd, pmu_fd;
> + int resultmap_fd, pidmap_fd;
> + struct perf_event_attr attr = {};
> + struct bpf_object *obj;
> + __u32 descendant_of_result = 0;
> + __u32 key = 0, pid;
> + int exit_code = EXIT_FAILURE;
> + char buf[256];
> +
> + int child_pid, ancestor_pid, root_fd, nonexistant = -42;
> + __u32 ancestor_key = 1;
> + int pipefd[2];
> + char marker[1];
> +
> + 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 fail;
> +
> + resultmap_fd = bpf_find_map(__func__, obj, "resultmap");
> + if (CHECK(resultmap_fd < 0, "bpf_find_map", "err %d errno %d\n",
> + resultmap_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);
> + bpf_map_update_elem(pidmap_fd, &ancestor_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;
Can you please switch all this to new libbpf tracing APIs? see
prog_tests/attach_probe.c for examples.
> +
> + // Test that descendant_of(current->pid) is true
> + bpf_map_update_elem(pidmap_fd, &key, &pid, 0);
> + bpf_map_update_elem(pidmap_fd, &ancestor_key, &pid, 0);
> + bpf_map_update_elem(resultmap_fd, &key, &nonexistant, 0);
> +
> + root_fd = open("/", O_RDONLY);
> + if (CHECK(efd < 0, "open", "errno %d\n", errno))
> + goto close_prog;
> + close(root_fd);
I'd suggest to just use raw_tracepoint 'sys_enter', which would be
easy to trigger with just `usleep(1)`. Makes for quite simpler code.
See, e.g., tools/testing/selftests/bpf/prog_tests/get_stack_raw_tp.c
> +
> + err = bpf_map_lookup_elem(resultmap_fd, &key, &descendant_of_result);
> + if (CHECK(err, "bpf_map_lookup_elem", "err %d errno %d\n", err, errno))
> + goto close_pmu;
> + if (CHECK(descendant_of_result != 1,
> + "descendant_of is true with same pid", "%d == %d\n",
> + descendant_of_result, 1))
> + goto close_pmu;
> +
<snip>
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