tools/bpf/bpftool/pids.c

   1 // SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
   2 /* Copyright (C) 2020 Facebook */
   3 #include <errno.h>
   4 #include <linux/err.h>
   5 #include <stdbool.h>
   6 #include <stdio.h>
   7 #include <stdlib.h>
   8 #include <string.h>
   9 #include <unistd.h>
  10
  11 #include <bpf/bpf.h>
  12 #include <bpf/hashmap.h>
  13
  14 #include "main.h"
  15 #include "skeleton/pid_iter.h"
  16
  17 #ifdef BPFTOOL_WITHOUT_SKELETONS
  18
  19 int build_obj_refs_table(struct hashmap **map, enum bpf_obj_type type)
  20 {
  21         return -ENOTSUP;
  22 }
  23 void delete_obj_refs_table(struct hashmap *map) {}
  24 void emit_obj_refs_plain(struct hashmap *map, __u32 id, const char *prefix) {}
  25 void emit_obj_refs_json(struct hashmap *map, __u32 id, json_writer_t *json_writer) {}
  26
  27 #else /* BPFTOOL_WITHOUT_SKELETONS */
  28
  29 #include "pid_iter.skel.h"
  30
  31 static void add_ref(struct hashmap *map, struct pid_iter_entry *e)
  32 {
  33         struct hashmap_entry *entry;
  34         struct obj_refs *refs;
  35         struct obj_ref *ref;
  36         int err, i;
  37         void *tmp;
  38
  39         hashmap__for_each_key_entry(map, entry, e->id) {
  40                 refs = entry->pvalue;
  41
  42                 for (i = 0; i < refs->ref_cnt; i++) {
  43                         if (refs->refs[i].pid == e->pid)
  44                                 return;
  45                 }
  46
  47                 tmp = realloc(refs->refs, (refs->ref_cnt + 1) * sizeof(*ref));
  48                 if (!tmp) {
  49                         p_err("failed to re-alloc memory for ID %u, PID %d, COMM %s...",
  50                               e->id, e->pid, e->comm);
  51                         return;
  52                 }
  53                 refs->refs = tmp;
  54                 ref = &refs->refs[refs->ref_cnt];
  55                 ref->pid = e->pid;
  56                 memcpy(ref->comm, e->comm, sizeof(ref->comm));
  57                 refs->ref_cnt++;
  58
  59                 return;
  60         }
  61
  62         /* new ref */
  63         refs = calloc(1, sizeof(*refs));
  64         if (!refs) {
  65                 p_err("failed to alloc memory for ID %u, PID %d, COMM %s...",
  66                       e->id, e->pid, e->comm);
  67                 return;
  68         }
  69
  70         refs->refs = malloc(sizeof(*refs->refs));
  71         if (!refs->refs) {
  72                 free(refs);
  73                 p_err("failed to alloc memory for ID %u, PID %d, COMM %s...",
  74                       e->id, e->pid, e->comm);
  75                 return;
  76         }
  77         ref = &refs->refs[0];
  78         ref->pid = e->pid;
  79         memcpy(ref->comm, e->comm, sizeof(ref->comm));
  80         refs->ref_cnt = 1;
  81         refs->has_bpf_cookie = e->has_bpf_cookie;
  82         refs->bpf_cookie = e->bpf_cookie;
  83
  84         err = hashmap__append(map, e->id, refs);
  85         if (err)
  86                 p_err("failed to append entry to hashmap for ID %u: %s",
  87                       e->id, strerror(errno));
  88 }
  89
  90 static int __printf(2, 0)
  91 libbpf_print_none(__maybe_unused enum libbpf_print_level level,
  92                   __maybe_unused const char *format,
  93                   __maybe_unused va_list args)
  94 {
  95         return 0;
  96 }
  97
  98 int build_obj_refs_table(struct hashmap **map, enum bpf_obj_type type)
  99 {
 100         struct pid_iter_entry *e;
 101         char buf[4096 / sizeof(*e) * sizeof(*e)];
 102         struct pid_iter_bpf *skel;
 103         int err, ret, fd = -1, i;
 104
 105         *map = hashmap__new(hash_fn_for_key_as_id, equal_fn_for_key_as_id, NULL);
 106         if (IS_ERR(*map)) {
 107                 p_err("failed to create hashmap for PID references");
 108                 return -1;
 109         }
 110         set_max_rlimit();
 111
 112         skel = pid_iter_bpf__open();
 113         if (!skel) {
 114                 p_err("failed to open PID iterator skeleton");
 115                 return -1;
 116         }
 117
 118         skel->rodata->obj_type = type;
 119
 120         if (!verifier_logs) {
 121                 libbpf_print_fn_t default_print;
 122
 123                 /* Unless debug information is on, we don't want the output to
 124                  * be polluted with libbpf errors if bpf_iter is not supported.
 125                  */
 126                 default_print = libbpf_set_print(libbpf_print_none);
 127                 err = pid_iter_bpf__load(skel);
 128                 libbpf_set_print(default_print);
 129         } else {
 130                 err = pid_iter_bpf__load(skel);
 131         }
 132         if (err) {
 133                 /* too bad, kernel doesn't support BPF iterators yet */
 134                 err = 0;
 135                 goto out;
 136         }
 137         err = pid_iter_bpf__attach(skel);
 138         if (err) {
 139                 /* if we loaded above successfully, attach has to succeed */
 140                 p_err("failed to attach PID iterator: %d", err);
 141                 goto out;
 142         }
 143
 144         fd = bpf_iter_create(bpf_link__fd(skel->links.iter));
 145         if (fd < 0) {
 146                 err = -errno;
 147                 p_err("failed to create PID iterator session: %d", err);
 148                 goto out;
 149         }
 150
 151         while (true) {
 152                 ret = read(fd, buf, sizeof(buf));
 153                 if (ret < 0) {
 154                         if (errno == EAGAIN)
 155                                 continue;
 156                         err = -errno;
 157                         p_err("failed to read PID iterator output: %d", err);
 158                         goto out;
 159                 }
 160                 if (ret == 0)
 161                         break;
 162                 if (ret % sizeof(*e)) {
 163                         err = -EINVAL;
 164                         p_err("invalid PID iterator output format");
 165                         goto out;
 166                 }
 167                 ret /= sizeof(*e);
 168
 169                 e = (void *)buf;
 170                 for (i = 0; i < ret; i++, e++) {
 171                         add_ref(*map, e);
 172                 }
 173         }
 174         err = 0;
 175 out:
 176         if (fd >= 0)
 177                 close(fd);
 178         pid_iter_bpf__destroy(skel);
 179         return err;
 180 }
 181
 182 void delete_obj_refs_table(struct hashmap *map)
 183 {
 184         struct hashmap_entry *entry;
 185         size_t bkt;
 186
 187         if (!map)
 188                 return;
 189
 190         hashmap__for_each_entry(map, entry, bkt) {
 191                 struct obj_refs *refs = entry->pvalue;
 192
 193                 free(refs->refs);
 194                 free(refs);
 195         }
 196
 197         hashmap__free(map);
 198 }
 199
 200 void emit_obj_refs_json(struct hashmap *map, __u32 id,
 201                         json_writer_t *json_writer)
 202 {
 203         struct hashmap_entry *entry;
 204
 205         if (hashmap__empty(map))
 206                 return;
 207
 208         hashmap__for_each_key_entry(map, entry, id) {
 209                 struct obj_refs *refs = entry->pvalue;
 210                 int i;
 211
 212                 if (refs->ref_cnt == 0)
 213                         break;
 214
 215                 if (refs->has_bpf_cookie)
 216                         jsonw_lluint_field(json_writer, "bpf_cookie", refs->bpf_cookie);
 217
 218                 jsonw_name(json_writer, "pids");
 219                 jsonw_start_array(json_writer);
 220                 for (i = 0; i < refs->ref_cnt; i++) {
 221                         struct obj_ref *ref = &refs->refs[i];
 222
 223                         jsonw_start_object(json_writer);
 224                         jsonw_int_field(json_writer, "pid", ref->pid);
 225                         jsonw_string_field(json_writer, "comm", ref->comm);
 226                         jsonw_end_object(json_writer);
 227                 }
 228                 jsonw_end_array(json_writer);
 229                 break;
 230         }
 231 }
 232
 233 void emit_obj_refs_plain(struct hashmap *map, __u32 id, const char *prefix)
 234 {
 235         struct hashmap_entry *entry;
 236
 237         if (hashmap__empty(map))
 238                 return;
 239
 240         hashmap__for_each_key_entry(map, entry, id) {
 241                 struct obj_refs *refs = entry->pvalue;
 242                 int i;
 243
 244                 if (refs->ref_cnt == 0)
 245                         break;
 246
 247                 if (refs->has_bpf_cookie)
 248                         printf("\n\tbpf_cookie %llu", (unsigned long long) refs->bpf_cookie);
 249
 250                 printf("%s", prefix);
 251                 for (i = 0; i < refs->ref_cnt; i++) {
 252                         struct obj_ref *ref = &refs->refs[i];
 253
 254                         printf("%s%s(%d)", i == 0 ? "" : ", ", ref->comm, ref->pid);
 255                 }
 256                 break;
 257         }
 258 }
 259
 260
 261 #endif