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         if (attr->value_size >= 1 << (KMALLOC_SHIFT_MAX - 1))
  32                 /* if value_size is bigger, the user space won't be able to
  33                  * access the elements.
  34                  */
  35                 return ERR_PTR(-E2BIG);
  36
  37         elem_size = round_up(attr->value_size, 8);
  38
  39         /* check round_up into zero and u32 overflow */
  40         if (elem_size == 0 ||
  41             attr->max_entries > (U32_MAX - PAGE_SIZE - sizeof(*array)) / elem_size)
  42                 return ERR_PTR(-ENOMEM);
  43
  44         array_size = sizeof(*array) + attr->max_entries * elem_size;
  45
  46         /* allocate all map elements and zero-initialize them */
  47         array = kzalloc(array_size, GFP_USER | __GFP_NOWARN);
  48         if (!array) {
  49                 array = vzalloc(array_size);
  50                 if (!array)
  51                         return ERR_PTR(-ENOMEM);
  52         }
  53
  54         /* copy mandatory map attributes */
  55         array->map.key_size = attr->key_size;
  56         array->map.value_size = attr->value_size;
  57         array->map.max_entries = attr->max_entries;
  58         array->map.pages = round_up(array_size, PAGE_SIZE) >> PAGE_SHIFT;
  59         array->elem_size = elem_size;
  60
  61         return &array->map;
  62 }
  63
  64 /* Called from syscall or from eBPF program */
  65 static void *array_map_lookup_elem(struct bpf_map *map, void *key)
  66 {
  67         struct bpf_array *array = container_of(map, struct bpf_array, map);
  68         u32 index = *(u32 *)key;
  69
  70         if (index >= array->map.max_entries)
  71                 return NULL;
  72
  73         return array->value + array->elem_size * index;
  74 }
  75
  76 /* Called from syscall */
  77 static int array_map_get_next_key(struct bpf_map *map, void *key, void *next_key)
  78 {
  79         struct bpf_array *array = container_of(map, struct bpf_array, map);
  80         u32 index = *(u32 *)key;
  81         u32 *next = (u32 *)next_key;
  82
  83         if (index >= array->map.max_entries) {
  84                 *next = 0;
  85                 return 0;
  86         }
  87
  88         if (index == array->map.max_entries - 1)
  89                 return -ENOENT;
  90
  91         *next = index + 1;
  92         return 0;
  93 }
  94
  95 /* Called from syscall or from eBPF program */
  96 static int array_map_update_elem(struct bpf_map *map, void *key, void *value,
  97                                  u64 map_flags)
  98 {
  99         struct bpf_array *array = container_of(map, struct bpf_array, map);
 100         u32 index = *(u32 *)key;
 101
 102         if (map_flags > BPF_EXIST)
 103                 /* unknown flags */
 104                 return -EINVAL;
 105
 106         if (index >= array->map.max_entries)
 107                 /* all elements were pre-allocated, cannot insert a new one */
 108                 return -E2BIG;
 109
 110         if (map_flags == BPF_NOEXIST)
 111                 /* all elements already exist */
 112                 return -EEXIST;
 113
 114         memcpy(array->value + array->elem_size * index, value, map->value_size);
 115         return 0;
 116 }
 117
 118 /* Called from syscall or from eBPF program */
 119 static int array_map_delete_elem(struct bpf_map *map, void *key)
 120 {
 121         return -EINVAL;
 122 }
 123
 124 /* Called when map->refcnt goes to zero, either from workqueue or from syscall */
 125 static void array_map_free(struct bpf_map *map)
 126 {
 127         struct bpf_array *array = container_of(map, struct bpf_array, map);
 128
 129         /* at this point bpf_prog->aux->refcnt == 0 and this map->refcnt == 0,
 130          * so the programs (can be more than one that used this map) were
 131          * disconnected from events. Wait for outstanding programs to complete
 132          * and free the array
 133          */
 134         synchronize_rcu();
 135
 136         kvfree(array);
 137 }
 138
 139 static const struct bpf_map_ops array_ops = {
 140         .map_alloc = array_map_alloc,
 141         .map_free = array_map_free,
 142         .map_get_next_key = array_map_get_next_key,
 143         .map_lookup_elem = array_map_lookup_elem,
 144         .map_update_elem = array_map_update_elem,
 145         .map_delete_elem = array_map_delete_elem,
 146 };
 147
 148 static struct bpf_map_type_list array_type __read_mostly = {
 149         .ops = &array_ops,
 150         .type = BPF_MAP_TYPE_ARRAY,
 151 };
 152
 153 static int __init register_array_map(void)
 154 {
 155         bpf_register_map_type(&array_type);
 156         return 0;
 157 }
 158 late_initcall(register_array_map);
 159
 160 static struct bpf_map *fd_array_map_alloc(union bpf_attr *attr)
 161 {
 162         /* only file descriptors can be stored in this type of map */
 163         if (attr->value_size != sizeof(u32))
 164                 return ERR_PTR(-EINVAL);
 165         return array_map_alloc(attr);
 166 }
 167
 168 static void fd_array_map_free(struct bpf_map *map)
 169 {
 170         struct bpf_array *array = container_of(map, struct bpf_array, map);
 171         int i;
 172
 173         synchronize_rcu();
 174
 175         /* make sure it's empty */
 176         for (i = 0; i < array->map.max_entries; i++)
 177                 BUG_ON(array->ptrs[i] != NULL);
 178         kvfree(array);
 179 }
 180
 181 static void *fd_array_map_lookup_elem(struct bpf_map *map, void *key)
 182 {
 183         return NULL;
 184 }
 185
 186 /* only called from syscall */
 187 static int fd_array_map_update_elem(struct bpf_map *map, void *key,
 188                                     void *value, u64 map_flags)
 189 {
 190         struct bpf_array *array = container_of(map, struct bpf_array, map);
 191         void *new_ptr, *old_ptr;
 192         u32 index = *(u32 *)key, ufd;
 193
 194         if (map_flags != BPF_ANY)
 195                 return -EINVAL;
 196
 197         if (index >= array->map.max_entries)
 198                 return -E2BIG;
 199
 200         ufd = *(u32 *)value;
 201         new_ptr = map->ops->map_fd_get_ptr(map, ufd);
 202         if (IS_ERR(new_ptr))
 203                 return PTR_ERR(new_ptr);
 204
 205         old_ptr = xchg(array->ptrs + index, new_ptr);
 206         if (old_ptr)
 207                 map->ops->map_fd_put_ptr(old_ptr);
 208
 209         return 0;
 210 }
 211
 212 static int fd_array_map_delete_elem(struct bpf_map *map, void *key)
 213 {
 214         struct bpf_array *array = container_of(map, struct bpf_array, map);
 215         void *old_ptr;
 216         u32 index = *(u32 *)key;
 217
 218         if (index >= array->map.max_entries)
 219                 return -E2BIG;
 220
 221         old_ptr = xchg(array->ptrs + index, NULL);
 222         if (old_ptr) {
 223                 map->ops->map_fd_put_ptr(old_ptr);
 224                 return 0;
 225         } else {
 226                 return -ENOENT;
 227         }
 228 }
 229
 230 static void *prog_fd_array_get_ptr(struct bpf_map *map, int fd)
 231 {
 232         struct bpf_array *array = container_of(map, struct bpf_array, map);
 233         struct bpf_prog *prog = bpf_prog_get(fd);
 234         if (IS_ERR(prog))
 235                 return prog;
 236
 237         if (!bpf_prog_array_compatible(array, prog)) {
 238                 bpf_prog_put(prog);
 239                 return ERR_PTR(-EINVAL);
 240         }
 241         return prog;
 242 }
 243
 244 static void prog_fd_array_put_ptr(void *ptr)
 245 {
 246         struct bpf_prog *prog = ptr;
 247
 248         bpf_prog_put_rcu(prog);
 249 }
 250
 251 /* decrement refcnt of all bpf_progs that are stored in this map */
 252 void bpf_fd_array_map_clear(struct bpf_map *map)
 253 {
 254         struct bpf_array *array = container_of(map, struct bpf_array, map);
 255         int i;
 256
 257         for (i = 0; i < array->map.max_entries; i++)
 258                 fd_array_map_delete_elem(map, &i);
 259 }
 260
 261 static const struct bpf_map_ops prog_array_ops = {
 262         .map_alloc = fd_array_map_alloc,
 263         .map_free = fd_array_map_free,
 264         .map_get_next_key = array_map_get_next_key,
 265         .map_lookup_elem = fd_array_map_lookup_elem,
 266         .map_update_elem = fd_array_map_update_elem,
 267         .map_delete_elem = fd_array_map_delete_elem,
 268         .map_fd_get_ptr = prog_fd_array_get_ptr,
 269         .map_fd_put_ptr = prog_fd_array_put_ptr,
 270 };
 271
 272 static struct bpf_map_type_list prog_array_type __read_mostly = {
 273         .ops = &prog_array_ops,
 274         .type = BPF_MAP_TYPE_PROG_ARRAY,
 275 };
 276
 277 static int __init register_prog_array_map(void)
 278 {
 279         bpf_register_map_type(&prog_array_type);
 280         return 0;
 281 }
 282 late_initcall(register_prog_array_map);
 283
 284 static void perf_event_array_map_free(struct bpf_map *map)
 285 {
 286         bpf_fd_array_map_clear(map);
 287         fd_array_map_free(map);
 288 }
 289
 290 static void *perf_event_fd_array_get_ptr(struct bpf_map *map, int fd)
 291 {
 292         struct perf_event *event;
 293         const struct perf_event_attr *attr;
 294         struct file *file;
 295
 296         file = perf_event_get(fd);
 297         if (IS_ERR(file))
 298                 return file;
 299
 300         event = file->private_data;
 301
 302         attr = perf_event_attrs(event);
 303         if (IS_ERR(attr))
 304                 goto err;
 305
 306         if (attr->inherit)
 307                 goto err;
 308
 309         if (attr->type == PERF_TYPE_RAW)
 310                 return file;
 311
 312         if (attr->type == PERF_TYPE_HARDWARE)
 313                 return file;
 314
 315         if (attr->type == PERF_TYPE_SOFTWARE &&
 316             attr->config == PERF_COUNT_SW_BPF_OUTPUT)
 317                 return file;
 318 err:
 319         fput(file);
 320         return ERR_PTR(-EINVAL);
 321 }
 322
 323 static void perf_event_fd_array_put_ptr(void *ptr)
 324 {
 325         fput((struct file *)ptr);
 326 }
 327
 328 static const struct bpf_map_ops perf_event_array_ops = {
 329         .map_alloc = fd_array_map_alloc,
 330         .map_free = perf_event_array_map_free,
 331         .map_get_next_key = array_map_get_next_key,
 332         .map_lookup_elem = fd_array_map_lookup_elem,
 333         .map_update_elem = fd_array_map_update_elem,
 334         .map_delete_elem = fd_array_map_delete_elem,
 335         .map_fd_get_ptr = perf_event_fd_array_get_ptr,
 336         .map_fd_put_ptr = perf_event_fd_array_put_ptr,
 337 };
 338
 339 static struct bpf_map_type_list perf_event_array_type __read_mostly = {
 340         .ops = &perf_event_array_ops,
 341         .type = BPF_MAP_TYPE_PERF_EVENT_ARRAY,
 342 };
 343
 344 static int __init register_perf_event_array_map(void)
 345 {
 346         bpf_register_map_type(&perf_event_array_type);
 347         return 0;
 348 }
 349 late_initcall(register_perf_event_array_map);