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(btf_bpf_map_id)
  82 BTF_ID(struct, bpf_map)
  83
  84 static const struct bpf_iter_seq_info bpf_map_seq_info = {
  85         .seq_ops                = &bpf_map_seq_ops,
  86         .init_seq_private       = NULL,
  87         .fini_seq_private       = NULL,
  88         .seq_priv_size          = sizeof(struct bpf_iter_seq_map_info),
  89 };
  90
  91 static struct bpf_iter_reg bpf_map_reg_info = {
  92         .target                 = "bpf_map",
  93         .ctx_arg_info_size      = 1,
  94         .ctx_arg_info           = {
  95                 { offsetof(struct bpf_iter__bpf_map, map),
  96                   PTR_TO_BTF_ID_OR_NULL },
  97         },
  98         .seq_info               = &bpf_map_seq_info,
  99 };
 100
 101 static int bpf_iter_attach_map(struct bpf_prog *prog,
 102                                union bpf_iter_link_info *linfo,
 103                                struct bpf_iter_aux_info *aux)
 104 {
 105         u32 key_acc_size, value_acc_size, key_size, value_size;
 106         struct bpf_map *map;
 107         bool is_percpu = false;
 108         int err = -EINVAL;
 109
 110         if (!linfo->map.map_fd)
 111                 return -EBADF;
 112
 113         map = bpf_map_get_with_uref(linfo->map.map_fd);
 114         if (IS_ERR(map))
 115                 return PTR_ERR(map);
 116
 117         if (map->map_type == BPF_MAP_TYPE_PERCPU_HASH ||
 118             map->map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH ||
 119             map->map_type == BPF_MAP_TYPE_PERCPU_ARRAY)
 120                 is_percpu = true;
 121         else if (map->map_type != BPF_MAP_TYPE_HASH &&
 122                  map->map_type != BPF_MAP_TYPE_LRU_HASH &&
 123                  map->map_type != BPF_MAP_TYPE_ARRAY)
 124                 goto put_map;
 125
 126         key_acc_size = prog->aux->max_rdonly_access;
 127         value_acc_size = prog->aux->max_rdwr_access;
 128         key_size = map->key_size;
 129         if (!is_percpu)
 130                 value_size = map->value_size;
 131         else
 132                 value_size = round_up(map->value_size, 8) * num_possible_cpus();
 133
 134         if (key_acc_size > key_size || value_acc_size > value_size) {
 135                 err = -EACCES;
 136                 goto put_map;
 137         }
 138
 139         aux->map = map;
 140         return 0;
 141
 142 put_map:
 143         bpf_map_put_with_uref(map);
 144         return err;
 145 }
 146
 147 static void bpf_iter_detach_map(struct bpf_iter_aux_info *aux)
 148 {
 149         bpf_map_put_with_uref(aux->map);
 150 }
 151
 152 void bpf_iter_map_show_fdinfo(const struct bpf_iter_aux_info *aux,
 153                               struct seq_file *seq)
 154 {
 155         seq_printf(seq, "map_id:\t%u\n", aux->map->id);
 156 }
 157
 158 int bpf_iter_map_fill_link_info(const struct bpf_iter_aux_info *aux,
 159                                 struct bpf_link_info *info)
 160 {
 161         info->iter.map.map_id = aux->map->id;
 162         return 0;
 163 }
 164
 165 DEFINE_BPF_ITER_FUNC(bpf_map_elem, struct bpf_iter_meta *meta,
 166                      struct bpf_map *map, void *key, void *value)
 167
 168 static const struct bpf_iter_reg bpf_map_elem_reg_info = {
 169         .target                 = "bpf_map_elem",
 170         .attach_target          = bpf_iter_attach_map,
 171         .detach_target          = bpf_iter_detach_map,
 172         .show_fdinfo            = bpf_iter_map_show_fdinfo,
 173         .fill_link_info         = bpf_iter_map_fill_link_info,
 174         .ctx_arg_info_size      = 2,
 175         .ctx_arg_info           = {
 176                 { offsetof(struct bpf_iter__bpf_map_elem, key),
 177                   PTR_TO_BUF | PTR_MAYBE_NULL | MEM_RDONLY },
 178                 { offsetof(struct bpf_iter__bpf_map_elem, value),
 179                   PTR_TO_BUF | PTR_MAYBE_NULL },
 180         },
 181 };
 182
 183 static int __init bpf_map_iter_init(void)
 184 {
 185         int ret;
 186
 187         bpf_map_reg_info.ctx_arg_info[0].btf_id = *btf_bpf_map_id;
 188         ret = bpf_iter_reg_target(&bpf_map_reg_info);
 189         if (ret)
 190                 return ret;
 191
 192         return bpf_iter_reg_target(&bpf_map_elem_reg_info);
 193 }
 194
 195 late_initcall(bpf_map_iter_init);