tools/testing/selftests/bpf/prog_tests/unpriv_bpf_disabled.c

   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 }