From: Alan Maguire <alan.maguire@oracle.com>
Date: Thu, 19 May 2022 15:25:34 +0100
Subject: selftests/bpf: add tests verifying unprivileged bpf behaviour
Patch-mainline: v5.19-rc1
Git-commit: 90a039fd19fc35d03a74ce2973992c878546cb20
References: jsc#PED-1377
tests load/attach bpf prog with maps, perfbuf and ringbuf, pinning
them. Then effective caps are dropped and we verify we can
- pick up the pin
- create ringbuf/perfbuf
- get ringbuf/perfbuf events, carry out map update, lookup and delete
- create a link
Negative testing also ensures
- BPF prog load fails
- BPF map create fails
- get fd by id fails
- get next id fails
- query fails
- BTF load fails
Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/r/1652970334-30510-3-git-send-email-alan.maguire@oracle.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
---
tools/testing/selftests/bpf/prog_tests/unpriv_bpf_disabled.c | 312 +++++++++++
tools/testing/selftests/bpf/progs/test_unpriv_bpf_disabled.c | 83 ++
2 files changed, 395 insertions(+)
create mode 100644 tools/testing/selftests/bpf/prog_tests/unpriv_bpf_disabled.c
create mode 100644 tools/testing/selftests/bpf/progs/test_unpriv_bpf_disabled.c
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/unpriv_bpf_disabled.c
@@ -0,0 +1,312 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2022, Oracle and/or its affiliates. */
+
+#include <test_progs.h>
+#include <bpf/btf.h>
+
+#include "test_unpriv_bpf_disabled.skel.h"
+
+#include "cap_helpers.h"
+
+/* Using CAP_LAST_CAP is risky here, since it can get pulled in from
+ * an old /usr/include/linux/capability.h and be < CAP_BPF; as a result
+ * CAP_BPF would not be included in ALL_CAPS. Instead use CAP_BPF as
+ * we know its value is correct since it is explicitly defined in
+ * cap_helpers.h.
+ */
+#define ALL_CAPS ((2ULL << CAP_BPF) - 1)
+
+#define PINPATH "/sys/fs/bpf/unpriv_bpf_disabled_"
+#define NUM_MAPS 7
+
+static __u32 got_perfbuf_val;
+static __u32 got_ringbuf_val;
+
+static int process_ringbuf(void *ctx, void *data, size_t len)
+{
+ if (ASSERT_EQ(len, sizeof(__u32), "ringbuf_size_valid"))
+ got_ringbuf_val = *(__u32 *)data;
+ return 0;
+}
+
+static void process_perfbuf(void *ctx, int cpu, void *data, __u32 len)
+{
+ if (ASSERT_EQ(len, sizeof(__u32), "perfbuf_size_valid"))
+ got_perfbuf_val = *(__u32 *)data;
+}
+
+static int sysctl_set(const char *sysctl_path, char *old_val, const char *new_val)
+{
+ int ret = 0;
+ FILE *fp;
+
+ fp = fopen(sysctl_path, "r+");
+ if (!fp)
+ return -errno;
+ if (old_val && fscanf(fp, "%s", old_val) <= 0) {
+ ret = -ENOENT;
+ } else if (!old_val || strcmp(old_val, new_val) != 0) {
+ fseek(fp, 0, SEEK_SET);
+ if (fprintf(fp, "%s", new_val) < 0)
+ ret = -errno;
+ }
+ fclose(fp);
+
+ return ret;
+}
+
+static void test_unpriv_bpf_disabled_positive(struct test_unpriv_bpf_disabled *skel,
+ __u32 prog_id, int prog_fd, int perf_fd,
+ char **map_paths, int *map_fds)
+{
+ struct perf_buffer *perfbuf = NULL;
+ struct ring_buffer *ringbuf = NULL;
+ int i, nr_cpus, link_fd = -1;
+
+ nr_cpus = bpf_num_possible_cpus();
+
+ skel->bss->perfbuf_val = 1;
+ skel->bss->ringbuf_val = 2;
+
+ /* Positive tests for unprivileged BPF disabled. Verify we can
+ * - retrieve and interact with pinned maps;
+ * - set up and interact with perf buffer;
+ * - set up and interact with ring buffer;
+ * - create a link
+ */
+ perfbuf = perf_buffer__new(bpf_map__fd(skel->maps.perfbuf), 8, process_perfbuf, NULL, NULL,
+ NULL);
+ if (!ASSERT_OK_PTR(perfbuf, "perf_buffer__new"))
+ goto cleanup;
+
+ ringbuf = ring_buffer__new(bpf_map__fd(skel->maps.ringbuf), process_ringbuf, NULL, NULL);
+ if (!ASSERT_OK_PTR(ringbuf, "ring_buffer__new"))
+ goto cleanup;
+
+ /* trigger & validate perf event, ringbuf output */
+ usleep(1);
+
+ ASSERT_GT(perf_buffer__poll(perfbuf, 100), -1, "perf_buffer__poll");
+ ASSERT_EQ(got_perfbuf_val, skel->bss->perfbuf_val, "check_perfbuf_val");
+ ASSERT_EQ(ring_buffer__consume(ringbuf), 1, "ring_buffer__consume");
+ ASSERT_EQ(got_ringbuf_val, skel->bss->ringbuf_val, "check_ringbuf_val");
+
+ for (i = 0; i < NUM_MAPS; i++) {
+ map_fds[i] = bpf_obj_get(map_paths[i]);
+ if (!ASSERT_GT(map_fds[i], -1, "obj_get"))
+ goto cleanup;
+ }
+
+ for (i = 0; i < NUM_MAPS; i++) {
+ bool prog_array = strstr(map_paths[i], "prog_array") != NULL;
+ bool array = strstr(map_paths[i], "array") != NULL;
+ bool buf = strstr(map_paths[i], "buf") != NULL;
+ __u32 key = 0, vals[nr_cpus], lookup_vals[nr_cpus];
+ __u32 expected_val = 1;
+ int j;
+
+ /* skip ringbuf, perfbuf */
+ if (buf)
+ continue;
+
+ for (j = 0; j < nr_cpus; j++)
+ vals[j] = expected_val;
+
+ if (prog_array) {
+ /* need valid prog array value */
+ vals[0] = prog_fd;
+ /* prog array lookup returns prog id, not fd */
+ expected_val = prog_id;
+ }
+ ASSERT_OK(bpf_map_update_elem(map_fds[i], &key, vals, 0), "map_update_elem");
+ ASSERT_OK(bpf_map_lookup_elem(map_fds[i], &key, &lookup_vals), "map_lookup_elem");
+ ASSERT_EQ(lookup_vals[0], expected_val, "map_lookup_elem_values");
+ if (!array)
+ ASSERT_OK(bpf_map_delete_elem(map_fds[i], &key), "map_delete_elem");
+ }
+
+ link_fd = bpf_link_create(bpf_program__fd(skel->progs.handle_perf_event), perf_fd,
+ BPF_PERF_EVENT, NULL);
+ ASSERT_GT(link_fd, 0, "link_create");
+
+cleanup:
+ if (link_fd)
+ close(link_fd);
+ if (perfbuf)
+ perf_buffer__free(perfbuf);
+ if (ringbuf)
+ ring_buffer__free(ringbuf);
+}
+
+static void test_unpriv_bpf_disabled_negative(struct test_unpriv_bpf_disabled *skel,
+ __u32 prog_id, int prog_fd, int perf_fd,
+ char **map_paths, int *map_fds)
+{
+ const struct bpf_insn prog_insns[] = {
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ };
+ const size_t prog_insn_cnt = sizeof(prog_insns) / sizeof(struct bpf_insn);
+ LIBBPF_OPTS(bpf_prog_load_opts, load_opts);
+ struct bpf_map_info map_info = {};
+ __u32 map_info_len = sizeof(map_info);
+ struct bpf_link_info link_info = {};
+ __u32 link_info_len = sizeof(link_info);
+ struct btf *btf = NULL;
+ __u32 attach_flags = 0;
+ __u32 prog_ids[3] = {};
+ __u32 prog_cnt = 3;
+ __u32 next;
+ int i;
+
+ /* Negative tests for unprivileged BPF disabled. Verify we cannot
+ * - load BPF programs;
+ * - create BPF maps;
+ * - get a prog/map/link fd by id;
+ * - get next prog/map/link id
+ * - query prog
+ * - BTF load
+ */
+ ASSERT_EQ(bpf_prog_load(BPF_PROG_TYPE_SOCKET_FILTER, "simple_prog", "GPL",
+ prog_insns, prog_insn_cnt, &load_opts),
+ -EPERM, "prog_load_fails");
+
+ for (i = BPF_MAP_TYPE_HASH; i <= BPF_MAP_TYPE_BLOOM_FILTER; i++)
+ ASSERT_EQ(bpf_map_create(i, NULL, sizeof(int), sizeof(int), 1, NULL),
+ -EPERM, "map_create_fails");
+
+ ASSERT_EQ(bpf_prog_get_fd_by_id(prog_id), -EPERM, "prog_get_fd_by_id_fails");
+ ASSERT_EQ(bpf_prog_get_next_id(prog_id, &next), -EPERM, "prog_get_next_id_fails");
+ ASSERT_EQ(bpf_prog_get_next_id(0, &next), -EPERM, "prog_get_next_id_fails");
+
+ if (ASSERT_OK(bpf_obj_get_info_by_fd(map_fds[0], &map_info, &map_info_len),
+ "obj_get_info_by_fd")) {
+ ASSERT_EQ(bpf_map_get_fd_by_id(map_info.id), -EPERM, "map_get_fd_by_id_fails");
+ ASSERT_EQ(bpf_map_get_next_id(map_info.id, &next), -EPERM,
+ "map_get_next_id_fails");
+ }
+ ASSERT_EQ(bpf_map_get_next_id(0, &next), -EPERM, "map_get_next_id_fails");
+
+ if (ASSERT_OK(bpf_obj_get_info_by_fd(bpf_link__fd(skel->links.sys_nanosleep_enter),
+ &link_info, &link_info_len),
+ "obj_get_info_by_fd")) {
+ ASSERT_EQ(bpf_link_get_fd_by_id(link_info.id), -EPERM, "link_get_fd_by_id_fails");
+ ASSERT_EQ(bpf_link_get_next_id(link_info.id, &next), -EPERM,
+ "link_get_next_id_fails");
+ }
+ ASSERT_EQ(bpf_link_get_next_id(0, &next), -EPERM, "link_get_next_id_fails");
+
+ ASSERT_EQ(bpf_prog_query(prog_fd, BPF_TRACE_FENTRY, 0, &attach_flags, prog_ids,
+ &prog_cnt), -EPERM, "prog_query_fails");
+
+ btf = btf__new_empty();
+ if (ASSERT_OK_PTR(btf, "empty_btf") &&
+ ASSERT_GT(btf__add_int(btf, "int", 4, 0), 0, "unpriv_int_type")) {
+ const void *raw_btf_data;
+ __u32 raw_btf_size;
+
+ raw_btf_data = btf__raw_data(btf, &raw_btf_size);
+ if (ASSERT_OK_PTR(raw_btf_data, "raw_btf_data_good"))
+ ASSERT_EQ(bpf_btf_load(raw_btf_data, raw_btf_size, NULL), -EPERM,
+ "bpf_btf_load_fails");
+ }
+ btf__free(btf);
+}
+
+void test_unpriv_bpf_disabled(void)
+{
+ char *map_paths[NUM_MAPS] = { PINPATH "array",
+ PINPATH "percpu_array",
+ PINPATH "hash",
+ PINPATH "percpu_hash",
+ PINPATH "perfbuf",
+ PINPATH "ringbuf",
+ PINPATH "prog_array" };
+ int map_fds[NUM_MAPS];
+ struct test_unpriv_bpf_disabled *skel;
+ char unprivileged_bpf_disabled_orig[32] = {};
+ char perf_event_paranoid_orig[32] = {};
+ struct bpf_prog_info prog_info = {};
+ __u32 prog_info_len = sizeof(prog_info);
+ struct perf_event_attr attr = {};
+ int prog_fd, perf_fd = -1, i, ret;
+ __u64 save_caps = 0;
+ __u32 prog_id;
+
+ skel = test_unpriv_bpf_disabled__open_and_load();
+ if (!ASSERT_OK_PTR(skel, "skel_open"))
+ return;
+
+ skel->bss->test_pid = getpid();
+
+ map_fds[0] = bpf_map__fd(skel->maps.array);
+ map_fds[1] = bpf_map__fd(skel->maps.percpu_array);
+ map_fds[2] = bpf_map__fd(skel->maps.hash);
+ map_fds[3] = bpf_map__fd(skel->maps.percpu_hash);
+ map_fds[4] = bpf_map__fd(skel->maps.perfbuf);
+ map_fds[5] = bpf_map__fd(skel->maps.ringbuf);
+ map_fds[6] = bpf_map__fd(skel->maps.prog_array);
+
+ for (i = 0; i < NUM_MAPS; i++)
+ ASSERT_OK(bpf_obj_pin(map_fds[i], map_paths[i]), "pin map_fd");
+
+ /* allow user without caps to use perf events */
+ if (!ASSERT_OK(sysctl_set("/proc/sys/kernel/perf_event_paranoid", perf_event_paranoid_orig,
+ "-1"),
+ "set_perf_event_paranoid"))
+ goto cleanup;
+ /* ensure unprivileged bpf disabled is set */
+ ret = sysctl_set("/proc/sys/kernel/unprivileged_bpf_disabled",
+ unprivileged_bpf_disabled_orig, "2");
+ if (ret == -EPERM) {
+ /* if unprivileged_bpf_disabled=1, we get -EPERM back; that's okay. */
+ if (!ASSERT_OK(strcmp(unprivileged_bpf_disabled_orig, "1"),
+ "unpriviliged_bpf_disabled_on"))
+ goto cleanup;
+ } else {
+ if (!ASSERT_OK(ret, "set unpriviliged_bpf_disabled"))
+ goto cleanup;
+ }
+
+ prog_fd = bpf_program__fd(skel->progs.sys_nanosleep_enter);
+ ASSERT_OK(bpf_obj_get_info_by_fd(prog_fd, &prog_info, &prog_info_len),
+ "obj_get_info_by_fd");
+ prog_id = prog_info.id;
+ ASSERT_GT(prog_id, 0, "valid_prog_id");
+
+ attr.size = sizeof(attr);
+ attr.type = PERF_TYPE_SOFTWARE;
+ attr.config = PERF_COUNT_SW_CPU_CLOCK;
+ attr.freq = 1;
+ attr.sample_freq = 1000;
+ perf_fd = syscall(__NR_perf_event_open, &attr, -1, 0, -1, PERF_FLAG_FD_CLOEXEC);
+ if (!ASSERT_GE(perf_fd, 0, "perf_fd"))
+ goto cleanup;
+
+ if (!ASSERT_OK(test_unpriv_bpf_disabled__attach(skel), "skel_attach"))
+ goto cleanup;
+
+ if (!ASSERT_OK(cap_disable_effective(ALL_CAPS, &save_caps), "disable caps"))
+ goto cleanup;
+
+ if (test__start_subtest("unpriv_bpf_disabled_positive"))
+ test_unpriv_bpf_disabled_positive(skel, prog_id, prog_fd, perf_fd, map_paths,
+ map_fds);
+
+ if (test__start_subtest("unpriv_bpf_disabled_negative"))
+ test_unpriv_bpf_disabled_negative(skel, prog_id, prog_fd, perf_fd, map_paths,
+ map_fds);
+
+cleanup:
+ close(perf_fd);
+ if (save_caps)
+ cap_enable_effective(save_caps, NULL);
+ if (strlen(perf_event_paranoid_orig) > 0)
+ sysctl_set("/proc/sys/kernel/perf_event_paranoid", NULL, perf_event_paranoid_orig);
+ if (strlen(unprivileged_bpf_disabled_orig) > 0)
+ sysctl_set("/proc/sys/kernel/unprivileged_bpf_disabled", NULL,
+ unprivileged_bpf_disabled_orig);
+ for (i = 0; i < NUM_MAPS; i++)
+ unlink(map_paths[i]);
+ test_unpriv_bpf_disabled__destroy(skel);
+}
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_unpriv_bpf_disabled.c
@@ -0,0 +1,83 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2022, Oracle and/or its affiliates. */
+
+#include "vmlinux.h"
+
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+#include "bpf_misc.h"
+
+__u32 perfbuf_val = 0;
+__u32 ringbuf_val = 0;
+
+int test_pid;
+
+struct {
+ __uint(type, BPF_MAP_TYPE_ARRAY);
+ __uint(max_entries, 1);
+ __type(key, __u32);
+ __type(value, __u32);
+} array SEC(".maps");
+
+struct {
+ __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
+ __uint(max_entries, 1);
+ __type(key, __u32);
+ __type(value, __u32);
+} percpu_array SEC(".maps");
+
+struct {
+ __uint(type, BPF_MAP_TYPE_HASH);
+ __uint(max_entries, 1);
+ __type(key, __u32);
+ __type(value, __u32);
+} hash SEC(".maps");
+
+struct {
+ __uint(type, BPF_MAP_TYPE_PERCPU_HASH);
+ __uint(max_entries, 1);
+ __type(key, __u32);
+ __type(value, __u32);
+} percpu_hash SEC(".maps");
+
+struct {
+ __uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
+ __type(key, __u32);
+ __type(value, __u32);
+} perfbuf SEC(".maps");
+
+struct {
+ __uint(type, BPF_MAP_TYPE_RINGBUF);
+ __uint(max_entries, 1 << 12);
+} ringbuf SEC(".maps");
+
+struct {
+ __uint(type, BPF_MAP_TYPE_PROG_ARRAY);
+ __uint(max_entries, 1);
+ __uint(key_size, sizeof(__u32));
+ __uint(value_size, sizeof(__u32));
+} prog_array SEC(".maps");
+
+SEC("fentry/" SYS_PREFIX "sys_nanosleep")
+int sys_nanosleep_enter(void *ctx)
+{
+ int cur_pid;
+
+ cur_pid = bpf_get_current_pid_tgid() >> 32;
+
+ if (cur_pid != test_pid)
+ return 0;
+
+ bpf_perf_event_output(ctx, &perfbuf, BPF_F_CURRENT_CPU, &perfbuf_val, sizeof(perfbuf_val));
+ bpf_ringbuf_output(&ringbuf, &ringbuf_val, sizeof(ringbuf_val), 0);
+
+ return 0;
+}
+
+SEC("perf_event")
+int handle_perf_event(void *ctx)
+{
+ return 0;
+}
+
+char _license[] SEC("license") = "GPL";