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         libbpf_print_fn_t default_print;
 105
 106         *map = hashmap__new(hash_fn_for_key_as_id, equal_fn_for_key_as_id, NULL);
 107         if (IS_ERR(*map)) {
 108                 p_err("failed to create hashmap for PID references");
 109                 return -1;
 110         }
 111         set_max_rlimit();
 112
 113         skel = pid_iter_bpf__open();
 114         if (!skel) {
 115                 p_err("failed to open PID iterator skeleton");
 116                 return -1;
 117         }
 118
 119         skel->rodata->obj_type = type;
 120
 121         /* we don't want output polluted with libbpf errors if bpf_iter is not
 122          * supported
 123          */
 124         default_print = libbpf_set_print(libbpf_print_none);
 125         err = pid_iter_bpf__load(skel);
 126         libbpf_set_print(default_print);
 127         if (err) {
 128                 /* too bad, kernel doesn't support BPF iterators yet */
 129                 err = 0;
 130                 goto out;
 131         }
 132         err = pid_iter_bpf__attach(skel);
 133         if (err) {
 134                 /* if we loaded above successfully, attach has to succeed */
 135                 p_err("failed to attach PID iterator: %d", err);
 136                 goto out;
 137         }
 138
 139         fd = bpf_iter_create(bpf_link__fd(skel->links.iter));
 140         if (fd < 0) {
 141                 err = -errno;
 142                 p_err("failed to create PID iterator session: %d", err);
 143                 goto out;
 144         }
 145
 146         while (true) {
 147                 ret = read(fd, buf, sizeof(buf));
 148                 if (ret < 0) {
 149                         if (errno == EAGAIN)
 150                                 continue;
 151                         err = -errno;
 152                         p_err("failed to read PID iterator output: %d", err);
 153                         goto out;
 154                 }
 155                 if (ret == 0)
 156                         break;
 157                 if (ret % sizeof(*e)) {
 158                         err = -EINVAL;
 159                         p_err("invalid PID iterator output format");
 160                         goto out;
 161                 }
 162                 ret /= sizeof(*e);
 163
 164                 e = (void *)buf;
 165                 for (i = 0; i < ret; i++, e++) {
 166                         add_ref(*map, e);
 167                 }
 168         }
 169         err = 0;
 170 out:
 171         if (fd >= 0)
 172                 close(fd);
 173         pid_iter_bpf__destroy(skel);
 174         return err;
 175 }
 176
 177 void delete_obj_refs_table(struct hashmap *map)
 178 {
 179         struct hashmap_entry *entry;
 180         size_t bkt;
 181
 182         if (!map)
 183                 return;
 184
 185         hashmap__for_each_entry(map, entry, bkt) {
 186                 struct obj_refs *refs = entry->pvalue;
 187
 188                 free(refs->refs);
 189                 free(refs);
 190         }
 191
 192         hashmap__free(map);
 193 }
 194
 195 void emit_obj_refs_json(struct hashmap *map, __u32 id,
 196                         json_writer_t *json_writer)
 197 {
 198         struct hashmap_entry *entry;
 199
 200         if (hashmap__empty(map))
 201                 return;
 202
 203         hashmap__for_each_key_entry(map, entry, id) {
 204                 struct obj_refs *refs = entry->pvalue;
 205                 int i;
 206
 207                 if (refs->ref_cnt == 0)
 208                         break;
 209
 210                 if (refs->has_bpf_cookie)
 211                         jsonw_lluint_field(json_writer, "bpf_cookie", refs->bpf_cookie);
 212
 213                 jsonw_name(json_writer, "pids");
 214                 jsonw_start_array(json_writer);
 215                 for (i = 0; i < refs->ref_cnt; i++) {
 216                         struct obj_ref *ref = &refs->refs[i];
 217
 218                         jsonw_start_object(json_writer);
 219                         jsonw_int_field(json_writer, "pid", ref->pid);
 220                         jsonw_string_field(json_writer, "comm", ref->comm);
 221                         jsonw_end_object(json_writer);
 222                 }
 223                 jsonw_end_array(json_writer);
 224                 break;
 225         }
 226 }
 227
 228 void emit_obj_refs_plain(struct hashmap *map, __u32 id, const char *prefix)
 229 {
 230         struct hashmap_entry *entry;
 231
 232         if (hashmap__empty(map))
 233                 return;
 234
 235         hashmap__for_each_key_entry(map, entry, id) {
 236                 struct obj_refs *refs = entry->pvalue;
 237                 int i;
 238
 239                 if (refs->ref_cnt == 0)
 240                         break;
 241
 242                 if (refs->has_bpf_cookie)
 243                         printf("\n\tbpf_cookie %llu", (unsigned long long) refs->bpf_cookie);
 244
 245                 printf("%s", prefix);
 246                 for (i = 0; i < refs->ref_cnt; i++) {
 247                         struct obj_ref *ref = &refs->refs[i];
 248
 249                         printf("%s%s(%d)", i == 0 ? "" : ", ", ref->comm, ref->pid);
 250                 }
 251                 break;
 252         }
 253 }
 254
 255
 256 #endif