1 // SPDX-License-Identifier: GPL-2.0
2 /* Copyright (c) 2022, Oracle and/or its affiliates. */
3 
4 #include <test_progs.h>
5 #include <bpf/btf.h>
6 
7 #include "test_unpriv_bpf_disabled.skel.h"
8 
9 #include "cap_helpers.h"
10 
11 /* Using CAP_LAST_CAP is risky here, since it can get pulled in from
12  * an old /usr/include/linux/capability.h and be < CAP_BPF; as a result
13  * CAP_BPF would not be included in ALL_CAPS.  Instead use CAP_BPF as
14  * we know its value is correct since it is explicitly defined in
15  * cap_helpers.h.
16  */
17 #define ALL_CAPS	((2ULL << CAP_BPF) - 1)
18 
19 #define PINPATH		"/sys/fs/bpf/unpriv_bpf_disabled_"
20 #define NUM_MAPS	7
21 
22 static __u32 got_perfbuf_val;
23 static __u32 got_ringbuf_val;
24 
25 static int process_ringbuf(void *ctx, void *data, size_t len)
26 {
27 	if (ASSERT_EQ(len, sizeof(__u32), "ringbuf_size_valid"))
28 		got_ringbuf_val = *(__u32 *)data;
29 	return 0;
30 }
31 
32 static void process_perfbuf(void *ctx, int cpu, void *data, __u32 len)
33 {
34 	if (ASSERT_EQ(len, sizeof(__u32), "perfbuf_size_valid"))
35 		got_perfbuf_val = *(__u32 *)data;
36 }
37 
38 static int sysctl_set(const char *sysctl_path, char *old_val, const char *new_val)
39 {
40 	int ret = 0;
41 	FILE *fp;
42 
43 	fp = fopen(sysctl_path, "r+");
44 	if (!fp)
45 		return -errno;
46 	if (old_val && fscanf(fp, "%s", old_val) <= 0) {
47 		ret = -ENOENT;
48 	} else if (!old_val || strcmp(old_val, new_val) != 0) {
49 		fseek(fp, 0, SEEK_SET);
50 		if (fprintf(fp, "%s", new_val) < 0)
51 			ret = -errno;
52 	}
53 	fclose(fp);
54 
55 	return ret;
56 }
57 
58 static void test_unpriv_bpf_disabled_positive(struct test_unpriv_bpf_disabled *skel,
59 					      __u32 prog_id, int prog_fd, int perf_fd,
60 					      char **map_paths, int *map_fds)
61 {
62 	struct perf_buffer *perfbuf = NULL;
63 	struct ring_buffer *ringbuf = NULL;
64 	int i, nr_cpus, link_fd = -1;
65 
66 	nr_cpus = bpf_num_possible_cpus();
67 
68 	skel->bss->perfbuf_val = 1;
69 	skel->bss->ringbuf_val = 2;
70 
71 	/* Positive tests for unprivileged BPF disabled. Verify we can
72 	 * - retrieve and interact with pinned maps;
73 	 * - set up and interact with perf buffer;
74 	 * - set up and interact with ring buffer;
75 	 * - create a link
76 	 */
77 	perfbuf = perf_buffer__new(bpf_map__fd(skel->maps.perfbuf), 8, process_perfbuf, NULL, NULL,
78 				   NULL);
79 	if (!ASSERT_OK_PTR(perfbuf, "perf_buffer__new"))
80 		goto cleanup;
81 
82 	ringbuf = ring_buffer__new(bpf_map__fd(skel->maps.ringbuf), process_ringbuf, NULL, NULL);
83 	if (!ASSERT_OK_PTR(ringbuf, "ring_buffer__new"))
84 		goto cleanup;
85 
86 	/* trigger & validate perf event, ringbuf output */
87 	usleep(1);
88 
89 	ASSERT_GT(perf_buffer__poll(perfbuf, 100), -1, "perf_buffer__poll");
90 	ASSERT_EQ(got_perfbuf_val, skel->bss->perfbuf_val, "check_perfbuf_val");
91 	ASSERT_EQ(ring_buffer__consume(ringbuf), 1, "ring_buffer__consume");
92 	ASSERT_EQ(got_ringbuf_val, skel->bss->ringbuf_val, "check_ringbuf_val");
93 
94 	for (i = 0; i < NUM_MAPS; i++) {
95 		map_fds[i] = bpf_obj_get(map_paths[i]);
96 		if (!ASSERT_GT(map_fds[i], -1, "obj_get"))
97 			goto cleanup;
98 	}
99 
100 	for (i = 0; i < NUM_MAPS; i++) {
101 		bool prog_array = strstr(map_paths[i], "prog_array") != NULL;
102 		bool array = strstr(map_paths[i], "array") != NULL;
103 		bool buf = strstr(map_paths[i], "buf") != NULL;
104 		__u32 key = 0, vals[nr_cpus], lookup_vals[nr_cpus];
105 		__u32 expected_val = 1;
106 		int j;
107 
108 		/* skip ringbuf, perfbuf */
109 		if (buf)
110 			continue;
111 
112 		for (j = 0; j < nr_cpus; j++)
113 			vals[j] = expected_val;
114 
115 		if (prog_array) {
116 			/* need valid prog array value */
117 			vals[0] = prog_fd;
118 			/* prog array lookup returns prog id, not fd */
119 			expected_val = prog_id;
120 		}
121 		ASSERT_OK(bpf_map_update_elem(map_fds[i], &key, vals, 0), "map_update_elem");
122 		ASSERT_OK(bpf_map_lookup_elem(map_fds[i], &key, &lookup_vals), "map_lookup_elem");
123 		ASSERT_EQ(lookup_vals[0], expected_val, "map_lookup_elem_values");
124 		if (!array)
125 			ASSERT_OK(bpf_map_delete_elem(map_fds[i], &key), "map_delete_elem");
126 	}
127 
128 	link_fd = bpf_link_create(bpf_program__fd(skel->progs.handle_perf_event), perf_fd,
129 				  BPF_PERF_EVENT, NULL);
130 	ASSERT_GT(link_fd, 0, "link_create");
131 
132 cleanup:
133 	if (link_fd)
134 		close(link_fd);
135 	if (perfbuf)
136 		perf_buffer__free(perfbuf);
137 	if (ringbuf)
138 		ring_buffer__free(ringbuf);
139 }
140 
141 static void test_unpriv_bpf_disabled_negative(struct test_unpriv_bpf_disabled *skel,
142 					      __u32 prog_id, int prog_fd, int perf_fd,
143 					      char **map_paths, int *map_fds)
144 {
145 	const struct bpf_insn prog_insns[] = {
146 		BPF_MOV64_IMM(BPF_REG_0, 0),
147 		BPF_EXIT_INSN(),
148 	};
149 	const size_t prog_insn_cnt = sizeof(prog_insns) / sizeof(struct bpf_insn);
150 	LIBBPF_OPTS(bpf_prog_load_opts, load_opts);
151 	struct bpf_map_info map_info = {};
152 	__u32 map_info_len = sizeof(map_info);
153 	struct bpf_link_info link_info = {};
154 	__u32 link_info_len = sizeof(link_info);
155 	struct btf *btf = NULL;
156 	__u32 attach_flags = 0;
157 	__u32 prog_ids[3] = {};
158 	__u32 prog_cnt = 3;
159 	__u32 next;
160 	int i;
161 
162 	/* Negative tests for unprivileged BPF disabled.  Verify we cannot
163 	 * - load BPF programs;
164 	 * - create BPF maps;
165 	 * - get a prog/map/link fd by id;
166 	 * - get next prog/map/link id
167 	 * - query prog
168 	 * - BTF load
169 	 */
170 	ASSERT_EQ(bpf_prog_load(BPF_PROG_TYPE_SOCKET_FILTER, "simple_prog", "GPL",
171 				prog_insns, prog_insn_cnt, &load_opts),
172 		  -EPERM, "prog_load_fails");
173 
174 	for (i = BPF_MAP_TYPE_HASH; i <= BPF_MAP_TYPE_BLOOM_FILTER; i++)
175 		ASSERT_EQ(bpf_map_create(i, NULL, sizeof(int), sizeof(int), 1, NULL),
176 			  -EPERM, "map_create_fails");
177 
178 	ASSERT_EQ(bpf_prog_get_fd_by_id(prog_id), -EPERM, "prog_get_fd_by_id_fails");
179 	ASSERT_EQ(bpf_prog_get_next_id(prog_id, &next), -EPERM, "prog_get_next_id_fails");
180 	ASSERT_EQ(bpf_prog_get_next_id(0, &next), -EPERM, "prog_get_next_id_fails");
181 
182 	if (ASSERT_OK(bpf_obj_get_info_by_fd(map_fds[0], &map_info, &map_info_len),
183 		      "obj_get_info_by_fd")) {
184 		ASSERT_EQ(bpf_map_get_fd_by_id(map_info.id), -EPERM, "map_get_fd_by_id_fails");
185 		ASSERT_EQ(bpf_map_get_next_id(map_info.id, &next), -EPERM,
186 			  "map_get_next_id_fails");
187 	}
188 	ASSERT_EQ(bpf_map_get_next_id(0, &next), -EPERM, "map_get_next_id_fails");
189 
190 	if (ASSERT_OK(bpf_obj_get_info_by_fd(bpf_link__fd(skel->links.sys_nanosleep_enter),
191 					     &link_info, &link_info_len),
192 		      "obj_get_info_by_fd")) {
193 		ASSERT_EQ(bpf_link_get_fd_by_id(link_info.id), -EPERM, "link_get_fd_by_id_fails");
194 		ASSERT_EQ(bpf_link_get_next_id(link_info.id, &next), -EPERM,
195 			  "link_get_next_id_fails");
196 	}
197 	ASSERT_EQ(bpf_link_get_next_id(0, &next), -EPERM, "link_get_next_id_fails");
198 
199 	ASSERT_EQ(bpf_prog_query(prog_fd, BPF_TRACE_FENTRY, 0, &attach_flags, prog_ids,
200 				 &prog_cnt), -EPERM, "prog_query_fails");
201 
202 	btf = btf__new_empty();
203 	if (ASSERT_OK_PTR(btf, "empty_btf") &&
204 	    ASSERT_GT(btf__add_int(btf, "int", 4, 0), 0, "unpriv_int_type")) {
205 		const void *raw_btf_data;
206 		__u32 raw_btf_size;
207 
208 		raw_btf_data = btf__raw_data(btf, &raw_btf_size);
209 		if (ASSERT_OK_PTR(raw_btf_data, "raw_btf_data_good"))
210 			ASSERT_EQ(bpf_btf_load(raw_btf_data, raw_btf_size, NULL), -EPERM,
211 				  "bpf_btf_load_fails");
212 	}
213 	btf__free(btf);
214 }
215 
216 void test_unpriv_bpf_disabled(void)
217 {
218 	char *map_paths[NUM_MAPS] = {	PINPATH	"array",
219 					PINPATH "percpu_array",
220 					PINPATH "hash",
221 					PINPATH "percpu_hash",
222 					PINPATH "perfbuf",
223 					PINPATH "ringbuf",
224 					PINPATH "prog_array" };
225 	int map_fds[NUM_MAPS];
226 	struct test_unpriv_bpf_disabled *skel;
227 	char unprivileged_bpf_disabled_orig[32] = {};
228 	char perf_event_paranoid_orig[32] = {};
229 	struct bpf_prog_info prog_info = {};
230 	__u32 prog_info_len = sizeof(prog_info);
231 	struct perf_event_attr attr = {};
232 	int prog_fd, perf_fd = -1, i, ret;
233 	__u64 save_caps = 0;
234 	__u32 prog_id;
235 
236 	skel = test_unpriv_bpf_disabled__open_and_load();
237 	if (!ASSERT_OK_PTR(skel, "skel_open"))
238 		return;
239 
240 	skel->bss->test_pid = getpid();
241 
242 	map_fds[0] = bpf_map__fd(skel->maps.array);
243 	map_fds[1] = bpf_map__fd(skel->maps.percpu_array);
244 	map_fds[2] = bpf_map__fd(skel->maps.hash);
245 	map_fds[3] = bpf_map__fd(skel->maps.percpu_hash);
246 	map_fds[4] = bpf_map__fd(skel->maps.perfbuf);
247 	map_fds[5] = bpf_map__fd(skel->maps.ringbuf);
248 	map_fds[6] = bpf_map__fd(skel->maps.prog_array);
249 
250 	for (i = 0; i < NUM_MAPS; i++)
251 		ASSERT_OK(bpf_obj_pin(map_fds[i], map_paths[i]), "pin map_fd");
252 
253 	/* allow user without caps to use perf events */
254 	if (!ASSERT_OK(sysctl_set("/proc/sys/kernel/perf_event_paranoid", perf_event_paranoid_orig,
255 				  "-1"),
256 		       "set_perf_event_paranoid"))
257 		goto cleanup;
258 	/* ensure unprivileged bpf disabled is set */
259 	ret = sysctl_set("/proc/sys/kernel/unprivileged_bpf_disabled",
260 			 unprivileged_bpf_disabled_orig, "2");
261 	if (ret == -EPERM) {
262 		/* if unprivileged_bpf_disabled=1, we get -EPERM back; that's okay. */
263 		if (!ASSERT_OK(strcmp(unprivileged_bpf_disabled_orig, "1"),
264 			       "unprivileged_bpf_disabled_on"))
265 			goto cleanup;
266 	} else {
267 		if (!ASSERT_OK(ret, "set unprivileged_bpf_disabled"))
268 			goto cleanup;
269 	}
270 
271 	prog_fd = bpf_program__fd(skel->progs.sys_nanosleep_enter);
272 	ASSERT_OK(bpf_obj_get_info_by_fd(prog_fd, &prog_info, &prog_info_len),
273 		  "obj_get_info_by_fd");
274 	prog_id = prog_info.id;
275 	ASSERT_GT(prog_id, 0, "valid_prog_id");
276 
277 	attr.size = sizeof(attr);
278 	attr.type = PERF_TYPE_SOFTWARE;
279 	attr.config = PERF_COUNT_SW_CPU_CLOCK;
280 	attr.freq = 1;
281 	attr.sample_freq = 1000;
282 	perf_fd = syscall(__NR_perf_event_open, &attr, -1, 0, -1, PERF_FLAG_FD_CLOEXEC);
283 	if (!ASSERT_GE(perf_fd, 0, "perf_fd"))
284 		goto cleanup;
285 
286 	if (!ASSERT_OK(test_unpriv_bpf_disabled__attach(skel), "skel_attach"))
287 		goto cleanup;
288 
289 	if (!ASSERT_OK(cap_disable_effective(ALL_CAPS, &save_caps), "disable caps"))
290 		goto cleanup;
291 
292 	if (test__start_subtest("unpriv_bpf_disabled_positive"))
293 		test_unpriv_bpf_disabled_positive(skel, prog_id, prog_fd, perf_fd, map_paths,
294 						  map_fds);
295 
296 	if (test__start_subtest("unpriv_bpf_disabled_negative"))
297 		test_unpriv_bpf_disabled_negative(skel, prog_id, prog_fd, perf_fd, map_paths,
298 						  map_fds);
299 
300 cleanup:
301 	close(perf_fd);
302 	if (save_caps)
303 		cap_enable_effective(save_caps, NULL);
304 	if (strlen(perf_event_paranoid_orig) > 0)
305 		sysctl_set("/proc/sys/kernel/perf_event_paranoid", NULL, perf_event_paranoid_orig);
306 	if (strlen(unprivileged_bpf_disabled_orig) > 0)
307 		sysctl_set("/proc/sys/kernel/unprivileged_bpf_disabled", NULL,
308 			   unprivileged_bpf_disabled_orig);
309 	for (i = 0; i < NUM_MAPS; i++)
310 		unlink(map_paths[i]);
311 	test_unpriv_bpf_disabled__destroy(skel);
312 }
313