kernel/bpf/arraymap.c

   1 /* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
   2  *
   3  * This program is free software; you can redistribute it and/or
   4  * modify it under the terms of version 2 of the GNU General Public
   5  * License as published by the Free Software Foundation.
   6  *
   7  * This program is distributed in the hope that it will be useful, but
   8  * WITHOUT ANY WARRANTY; without even the implied warranty of
   9  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  10  * General Public License for more details.
  11  */
  12 #include <linux/bpf.h>
  13 #include <linux/err.h>
  14 #include <linux/vmalloc.h>
  15 #include <linux/slab.h>
  16 #include <linux/mm.h>
  17 #include <linux/filter.h>
  18 #include <linux/perf_event.h>
  19
  20 /* Called from syscall */
  21 static struct bpf_map *array_map_alloc(union bpf_attr *attr)
  22 {
  23         struct bpf_array *array;
  24         u32 elem_size, array_size;
  25
  26         /* check sanity of attributes */
  27         if (attr->max_entries == 0 || attr->key_size != 4 ||
  28             attr->value_size == 0)
  29                 return ERR_PTR(-EINVAL);
  30
  31         elem_size = round_up(attr->value_size, 8);
  32
  33         /* check round_up into zero and u32 overflow */
  34         if (elem_size == 0 ||
  35             attr->max_entries > (U32_MAX - sizeof(*array)) / elem_size)
  36                 return ERR_PTR(-ENOMEM);
  37
  38         array_size = sizeof(*array) + attr->max_entries * elem_size;
  39
  40         /* allocate all map elements and zero-initialize them */
  41         array = kzalloc(array_size, GFP_USER | __GFP_NOWARN);
  42         if (!array) {
  43                 array = vzalloc(array_size);
  44                 if (!array)
  45                         return ERR_PTR(-ENOMEM);
  46         }
  47
  48         /* copy mandatory map attributes */
  49         array->map.key_size = attr->key_size;
  50         array->map.value_size = attr->value_size;
  51         array->map.max_entries = attr->max_entries;
  52         array->map.pages = round_up(array_size, PAGE_SIZE) >> PAGE_SHIFT;
  53         array->elem_size = elem_size;
  54
  55         return &array->map;
  56 }
  57
  58 /* Called from syscall or from eBPF program */
  59 static void *array_map_lookup_elem(struct bpf_map *map, void *key)
  60 {
  61         struct bpf_array *array = container_of(map, struct bpf_array, map);
  62         u32 index = *(u32 *)key;
  63
  64         if (index >= array->map.max_entries)
  65                 return NULL;
  66
  67         return array->value + array->elem_size * index;
  68 }
  69
  70 /* Called from syscall */
  71 static int array_map_get_next_key(struct bpf_map *map, void *key, void *next_key)
  72 {
  73         struct bpf_array *array = container_of(map, struct bpf_array, map);
  74         u32 index = *(u32 *)key;
  75         u32 *next = (u32 *)next_key;
  76
  77         if (index >= array->map.max_entries) {
  78                 *next = 0;
  79                 return 0;
  80         }
  81
  82         if (index == array->map.max_entries - 1)
  83                 return -ENOENT;
  84
  85         *next = index + 1;
  86         return 0;
  87 }
  88
  89 /* Called from syscall or from eBPF program */
  90 static int array_map_update_elem(struct bpf_map *map, void *key, void *value,
  91                                  u64 map_flags)
  92 {
  93         struct bpf_array *array = container_of(map, struct bpf_array, map);
  94         u32 index = *(u32 *)key;
  95
  96         if (map_flags > BPF_EXIST)
  97                 /* unknown flags */
  98                 return -EINVAL;
  99
 100         if (index >= array->map.max_entries)
 101                 /* all elements were pre-allocated, cannot insert a new one */
 102                 return -E2BIG;
 103
 104         if (map_flags == BPF_NOEXIST)
 105                 /* all elements already exist */
 106                 return -EEXIST;
 107
 108         memcpy(array->value + array->elem_size * index, value, array->elem_size);
 109         return 0;
 110 }
 111
 112 /* Called from syscall or from eBPF program */
 113 static int array_map_delete_elem(struct bpf_map *map, void *key)
 114 {
 115         return -EINVAL;
 116 }
 117
 118 /* Called when map->refcnt goes to zero, either from workqueue or from syscall */
 119 static void array_map_free(struct bpf_map *map)
 120 {
 121         struct bpf_array *array = container_of(map, struct bpf_array, map);
 122
 123         /* at this point bpf_prog->aux->refcnt == 0 and this map->refcnt == 0,
 124          * so the programs (can be more than one that used this map) were
 125          * disconnected from events. Wait for outstanding programs to complete
 126          * and free the array
 127          */
 128         synchronize_rcu();
 129
 130         kvfree(array);
 131 }
 132
 133 static const struct bpf_map_ops array_ops = {
 134         .map_alloc = array_map_alloc,
 135         .map_free = array_map_free,
 136         .map_get_next_key = array_map_get_next_key,
 137         .map_lookup_elem = array_map_lookup_elem,
 138         .map_update_elem = array_map_update_elem,
 139         .map_delete_elem = array_map_delete_elem,
 140 };
 141
 142 static struct bpf_map_type_list array_type __read_mostly = {
 143         .ops = &array_ops,
 144         .type = BPF_MAP_TYPE_ARRAY,
 145 };
 146
 147 static int __init register_array_map(void)
 148 {
 149         bpf_register_map_type(&array_type);
 150         return 0;
 151 }
 152 late_initcall(register_array_map);
 153
 154 static struct bpf_map *fd_array_map_alloc(union bpf_attr *attr)
 155 {
 156         /* only file descriptors can be stored in this type of map */
 157         if (attr->value_size != sizeof(u32))
 158                 return ERR_PTR(-EINVAL);
 159         return array_map_alloc(attr);
 160 }
 161
 162 static void fd_array_map_free(struct bpf_map *map)
 163 {
 164         struct bpf_array *array = container_of(map, struct bpf_array, map);
 165         int i;
 166
 167         synchronize_rcu();
 168
 169         /* make sure it's empty */
 170         for (i = 0; i < array->map.max_entries; i++)
 171                 BUG_ON(array->ptrs[i] != NULL);
 172         kvfree(array);
 173 }
 174
 175 static void *fd_array_map_lookup_elem(struct bpf_map *map, void *key)
 176 {
 177         return NULL;
 178 }
 179
 180 /* only called from syscall */
 181 static int fd_array_map_update_elem(struct bpf_map *map, void *key,
 182                                     void *value, u64 map_flags)
 183 {
 184         struct bpf_array *array = container_of(map, struct bpf_array, map);
 185         void *new_ptr, *old_ptr;
 186         u32 index = *(u32 *)key, ufd;
 187
 188         if (map_flags != BPF_ANY)
 189                 return -EINVAL;
 190
 191         if (index >= array->map.max_entries)
 192                 return -E2BIG;
 193
 194         ufd = *(u32 *)value;
 195         new_ptr = map->ops->map_fd_get_ptr(map, ufd);
 196         if (IS_ERR(new_ptr))
 197                 return PTR_ERR(new_ptr);
 198
 199         old_ptr = xchg(array->ptrs + index, new_ptr);
 200         if (old_ptr)
 201                 map->ops->map_fd_put_ptr(old_ptr);
 202
 203         return 0;
 204 }
 205
 206 static int fd_array_map_delete_elem(struct bpf_map *map, void *key)
 207 {
 208         struct bpf_array *array = container_of(map, struct bpf_array, map);
 209         void *old_ptr;
 210         u32 index = *(u32 *)key;
 211
 212         if (index >= array->map.max_entries)
 213                 return -E2BIG;
 214
 215         old_ptr = xchg(array->ptrs + index, NULL);
 216         if (old_ptr) {
 217                 map->ops->map_fd_put_ptr(old_ptr);
 218                 return 0;
 219         } else {
 220                 return -ENOENT;
 221         }
 222 }
 223
 224 static void *prog_fd_array_get_ptr(struct bpf_map *map, int fd)
 225 {
 226         struct bpf_array *array = container_of(map, struct bpf_array, map);
 227         struct bpf_prog *prog = bpf_prog_get(fd);
 228         if (IS_ERR(prog))
 229                 return prog;
 230
 231         if (!bpf_prog_array_compatible(array, prog)) {
 232                 bpf_prog_put(prog);
 233                 return ERR_PTR(-EINVAL);
 234         }
 235         return prog;
 236 }
 237
 238 static void prog_fd_array_put_ptr(void *ptr)
 239 {
 240         struct bpf_prog *prog = ptr;
 241
 242         bpf_prog_put_rcu(prog);
 243 }
 244
 245 /* decrement refcnt of all bpf_progs that are stored in this map */
 246 void bpf_fd_array_map_clear(struct bpf_map *map)
 247 {
 248         struct bpf_array *array = container_of(map, struct bpf_array, map);
 249         int i;
 250
 251         for (i = 0; i < array->map.max_entries; i++)
 252                 fd_array_map_delete_elem(map, &i);
 253 }
 254
 255 static const struct bpf_map_ops prog_array_ops = {
 256         .map_alloc = fd_array_map_alloc,
 257         .map_free = fd_array_map_free,
 258         .map_get_next_key = array_map_get_next_key,
 259         .map_lookup_elem = fd_array_map_lookup_elem,
 260         .map_update_elem = fd_array_map_update_elem,
 261         .map_delete_elem = fd_array_map_delete_elem,
 262         .map_fd_get_ptr = prog_fd_array_get_ptr,
 263         .map_fd_put_ptr = prog_fd_array_put_ptr,
 264 };
 265
 266 static struct bpf_map_type_list prog_array_type __read_mostly = {
 267         .ops = &prog_array_ops,
 268         .type = BPF_MAP_TYPE_PROG_ARRAY,
 269 };
 270
 271 static int __init register_prog_array_map(void)
 272 {
 273         bpf_register_map_type(&prog_array_type);
 274         return 0;
 275 }
 276 late_initcall(register_prog_array_map);
 277
 278 static void perf_event_array_map_free(struct bpf_map *map)
 279 {
 280         bpf_fd_array_map_clear(map);
 281         fd_array_map_free(map);
 282 }
 283
 284 static void *perf_event_fd_array_get_ptr(struct bpf_map *map, int fd)
 285 {
 286         struct perf_event *event;
 287         const struct perf_event_attr *attr;
 288
 289         event = perf_event_get(fd);
 290         if (IS_ERR(event))
 291                 return event;
 292
 293         attr = perf_event_attrs(event);
 294         if (IS_ERR(attr))
 295                 goto err;
 296
 297         if (attr->inherit)
 298                 goto err;
 299
 300         if (attr->type == PERF_TYPE_RAW)
 301                 return event;
 302
 303         if (attr->type == PERF_TYPE_HARDWARE)
 304                 return event;
 305
 306         if (attr->type == PERF_TYPE_SOFTWARE &&
 307             attr->config == PERF_COUNT_SW_BPF_OUTPUT)
 308                 return event;
 309 err:
 310         perf_event_release_kernel(event);
 311         return ERR_PTR(-EINVAL);
 312 }
 313
 314 static void perf_event_fd_array_put_ptr(void *ptr)
 315 {
 316         struct perf_event *event = ptr;
 317
 318         perf_event_release_kernel(event);
 319 }
 320
 321 static const struct bpf_map_ops perf_event_array_ops = {
 322         .map_alloc = fd_array_map_alloc,
 323         .map_free = perf_event_array_map_free,
 324         .map_get_next_key = array_map_get_next_key,
 325         .map_lookup_elem = fd_array_map_lookup_elem,
 326         .map_update_elem = fd_array_map_update_elem,
 327         .map_delete_elem = fd_array_map_delete_elem,
 328         .map_fd_get_ptr = perf_event_fd_array_get_ptr,
 329         .map_fd_put_ptr = perf_event_fd_array_put_ptr,
 330 };
 331
 332 static struct bpf_map_type_list perf_event_array_type __read_mostly = {
 333         .ops = &perf_event_array_ops,
 334         .type = BPF_MAP_TYPE_PERF_EVENT_ARRAY,
 335 };
 336
 337 static int __init register_perf_event_array_map(void)
 338 {
 339         bpf_register_map_type(&perf_event_array_type);
 340         return 0;
 341 }
 342 late_initcall(register_perf_event_array_map);