kernel/bpf/map_iter.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /* Copyright (c) 2020 Facebook */
   3 #include <linux/bpf.h>
   4 #include <linux/fs.h>
   5 #include <linux/filter.h>
   6 #include <linux/kernel.h>
   7 #include <linux/btf_ids.h>
   8
   9 struct bpf_iter_seq_map_info {
  10         u32 map_id;
  11 };
  12
  13 static void *bpf_map_seq_start(struct seq_file *seq, loff_t *pos)
  14 {
  15         struct bpf_iter_seq_map_info *info = seq->private;
  16         struct bpf_map *map;
  17
  18         map = bpf_map_get_curr_or_next(&info->map_id);
  19         if (!map)
  20                 return NULL;
  21
  22         if (*pos == 0)
  23                 ++*pos;
  24         return map;
  25 }
  26
  27 static void *bpf_map_seq_next(struct seq_file *seq, void *v, loff_t *pos)
  28 {
  29         struct bpf_iter_seq_map_info *info = seq->private;
  30
  31         ++*pos;
  32         ++info->map_id;
  33         bpf_map_put((struct bpf_map *)v);
  34         return bpf_map_get_curr_or_next(&info->map_id);
  35 }
  36
  37 struct bpf_iter__bpf_map {
  38         __bpf_md_ptr(struct bpf_iter_meta *, meta);
  39         __bpf_md_ptr(struct bpf_map *, map);
  40 };
  41
  42 DEFINE_BPF_ITER_FUNC(bpf_map, struct bpf_iter_meta *meta, struct bpf_map *map)
  43
  44 static int __bpf_map_seq_show(struct seq_file *seq, void *v, bool in_stop)
  45 {
  46         struct bpf_iter__bpf_map ctx;
  47         struct bpf_iter_meta meta;
  48         struct bpf_prog *prog;
  49         int ret = 0;
  50
  51         ctx.meta = &meta;
  52         ctx.map = v;
  53         meta.seq = seq;
  54         prog = bpf_iter_get_info(&meta, in_stop);
  55         if (prog)
  56                 ret = bpf_iter_run_prog(prog, &ctx);
  57
  58         return ret;
  59 }
  60
  61 static int bpf_map_seq_show(struct seq_file *seq, void *v)
  62 {
  63         return __bpf_map_seq_show(seq, v, false);
  64 }
  65
  66 static void bpf_map_seq_stop(struct seq_file *seq, void *v)
  67 {
  68         if (!v)
  69                 (void)__bpf_map_seq_show(seq, v, true);
  70         else
  71                 bpf_map_put((struct bpf_map *)v);
  72 }
  73
  74 static const struct seq_operations bpf_map_seq_ops = {
  75         .start  = bpf_map_seq_start,
  76         .next   = bpf_map_seq_next,
  77         .stop   = bpf_map_seq_stop,
  78         .show   = bpf_map_seq_show,
  79 };
  80
  81 BTF_ID_LIST_GLOBAL_SINGLE(btf_bpf_map_id, struct, bpf_map)
  82
  83 static const struct bpf_iter_seq_info bpf_map_seq_info = {
  84         .seq_ops                = &bpf_map_seq_ops,
  85         .init_seq_private       = NULL,
  86         .fini_seq_private       = NULL,
  87         .seq_priv_size          = sizeof(struct bpf_iter_seq_map_info),
  88 };
  89
  90 static struct bpf_iter_reg bpf_map_reg_info = {
  91         .target                 = "bpf_map",
  92         .ctx_arg_info_size      = 1,
  93         .ctx_arg_info           = {
  94                 { offsetof(struct bpf_iter__bpf_map, map),
  95                   PTR_TO_BTF_ID_OR_NULL | PTR_TRUSTED },
  96         },
  97         .seq_info               = &bpf_map_seq_info,
  98 };
  99
 100 static int bpf_iter_attach_map(struct bpf_prog *prog,
 101                                union bpf_iter_link_info *linfo,
 102                                struct bpf_iter_aux_info *aux)
 103 {
 104         u32 key_acc_size, value_acc_size, key_size, value_size;
 105         struct bpf_map *map;
 106         bool is_percpu = false;
 107         int err = -EINVAL;
 108
 109         if (!linfo->map.map_fd)
 110                 return -EBADF;
 111
 112         map = bpf_map_get_with_uref(linfo->map.map_fd);
 113         if (IS_ERR(map))
 114                 return PTR_ERR(map);
 115
 116         if (map->map_type == BPF_MAP_TYPE_PERCPU_HASH ||
 117             map->map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH ||
 118             map->map_type == BPF_MAP_TYPE_PERCPU_ARRAY)
 119                 is_percpu = true;
 120         else if (map->map_type != BPF_MAP_TYPE_HASH &&
 121                  map->map_type != BPF_MAP_TYPE_LRU_HASH &&
 122                  map->map_type != BPF_MAP_TYPE_ARRAY)
 123                 goto put_map;
 124
 125         key_acc_size = prog->aux->max_rdonly_access;
 126         value_acc_size = prog->aux->max_rdwr_access;
 127         key_size = map->key_size;
 128         if (!is_percpu)
 129                 value_size = map->value_size;
 130         else
 131                 value_size = round_up(map->value_size, 8) * num_possible_cpus();
 132
 133         if (key_acc_size > key_size || value_acc_size > value_size) {
 134                 err = -EACCES;
 135                 goto put_map;
 136         }
 137
 138         aux->map = map;
 139         return 0;
 140
 141 put_map:
 142         bpf_map_put_with_uref(map);
 143         return err;
 144 }
 145
 146 static void bpf_iter_detach_map(struct bpf_iter_aux_info *aux)
 147 {
 148         bpf_map_put_with_uref(aux->map);
 149 }
 150
 151 void bpf_iter_map_show_fdinfo(const struct bpf_iter_aux_info *aux,
 152                               struct seq_file *seq)
 153 {
 154         seq_printf(seq, "map_id:\t%u\n", aux->map->id);
 155 }
 156
 157 int bpf_iter_map_fill_link_info(const struct bpf_iter_aux_info *aux,
 158                                 struct bpf_link_info *info)
 159 {
 160         info->iter.map.map_id = aux->map->id;
 161         return 0;
 162 }
 163
 164 DEFINE_BPF_ITER_FUNC(bpf_map_elem, struct bpf_iter_meta *meta,
 165                      struct bpf_map *map, void *key, void *value)
 166
 167 static const struct bpf_iter_reg bpf_map_elem_reg_info = {
 168         .target                 = "bpf_map_elem",
 169         .attach_target          = bpf_iter_attach_map,
 170         .detach_target          = bpf_iter_detach_map,
 171         .show_fdinfo            = bpf_iter_map_show_fdinfo,
 172         .fill_link_info         = bpf_iter_map_fill_link_info,
 173         .ctx_arg_info_size      = 2,
 174         .ctx_arg_info           = {
 175                 { offsetof(struct bpf_iter__bpf_map_elem, key),
 176                   PTR_TO_BUF | PTR_MAYBE_NULL | MEM_RDONLY },
 177                 { offsetof(struct bpf_iter__bpf_map_elem, value),
 178                   PTR_TO_BUF | PTR_MAYBE_NULL },
 179         },
 180 };
 181
 182 static int __init bpf_map_iter_init(void)
 183 {
 184         int ret;
 185
 186         bpf_map_reg_info.ctx_arg_info[0].btf_id = *btf_bpf_map_id;
 187         ret = bpf_iter_reg_target(&bpf_map_reg_info);
 188         if (ret)
 189                 return ret;
 190
 191         return bpf_iter_reg_target(&bpf_map_elem_reg_info);
 192 }
 193
 194 late_initcall(bpf_map_iter_init);
 195
 196 __bpf_kfunc_start_defs();
 197
 198 __bpf_kfunc s64 bpf_map_sum_elem_count(const struct bpf_map *map)
 199 {
 200         s64 *pcount;
 201         s64 ret = 0;
 202         int cpu;
 203
 204         if (!map || !map->elem_count)
 205                 return 0;
 206
 207         for_each_possible_cpu(cpu) {
 208                 pcount = per_cpu_ptr(map->elem_count, cpu);
 209                 ret += READ_ONCE(*pcount);
 210         }
 211         return ret;
 212 }
 213
 214 __bpf_kfunc_end_defs();
 215
 216 BTF_KFUNCS_START(bpf_map_iter_kfunc_ids)
 217 BTF_ID_FLAGS(func, bpf_map_sum_elem_count, KF_TRUSTED_ARGS)
 218 BTF_KFUNCS_END(bpf_map_iter_kfunc_ids)
 219
 220 static const struct btf_kfunc_id_set bpf_map_iter_kfunc_set = {
 221         .owner = THIS_MODULE,
 222         .set   = &bpf_map_iter_kfunc_ids,
 223 };
 224
 225 static int init_subsystem(void)
 226 {
 227         return register_btf_kfunc_id_set(BPF_PROG_TYPE_UNSPEC, &bpf_map_iter_kfunc_set);
 228 }
 229 late_initcall(init_subsystem);