net/core/bpf_sk_storage.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /* Copyright (c) 2019 Facebook  */
   3 #include <linux/rculist.h>
   4 #include <linux/list.h>
   5 #include <linux/hash.h>
   6 #include <linux/types.h>
   7 #include <linux/spinlock.h>
   8 #include <linux/bpf.h>
   9 #include <linux/btf.h>
  10 #include <linux/btf_ids.h>
  11 #include <linux/bpf_local_storage.h>
  12 #include <net/bpf_sk_storage.h>
  13 #include <net/sock.h>
  14 #include <uapi/linux/sock_diag.h>
  15 #include <uapi/linux/btf.h>
  16
  17 DEFINE_BPF_STORAGE_CACHE(sk_cache);
  18
  19 static struct bpf_local_storage_data *
  20 bpf_sk_storage_lookup(struct sock *sk, struct bpf_map *map, bool cacheit_lockit)
  21 {
  22         struct bpf_local_storage *sk_storage;
  23         struct bpf_local_storage_map *smap;
  24
  25         sk_storage = rcu_dereference(sk->sk_bpf_storage);
  26         if (!sk_storage)
  27                 return NULL;
  28
  29         smap = (struct bpf_local_storage_map *)map;
  30         return bpf_local_storage_lookup(sk_storage, smap, cacheit_lockit);
  31 }
  32
  33 static int bpf_sk_storage_del(struct sock *sk, struct bpf_map *map)
  34 {
  35         struct bpf_local_storage_data *sdata;
  36
  37         sdata = bpf_sk_storage_lookup(sk, map, false);
  38         if (!sdata)
  39                 return -ENOENT;
  40
  41         bpf_selem_unlink(SELEM(sdata));
  42
  43         return 0;
  44 }
  45
  46 /* Called by __sk_destruct() & bpf_sk_storage_clone() */
  47 void bpf_sk_storage_free(struct sock *sk)
  48 {
  49         struct bpf_local_storage_elem *selem;
  50         struct bpf_local_storage *sk_storage;
  51         bool free_sk_storage = false;
  52         struct hlist_node *n;
  53
  54         rcu_read_lock();
  55         sk_storage = rcu_dereference(sk->sk_bpf_storage);
  56         if (!sk_storage) {
  57                 rcu_read_unlock();
  58                 return;
  59         }
  60
  61         /* Netiher the bpf_prog nor the bpf-map's syscall
  62          * could be modifying the sk_storage->list now.
  63          * Thus, no elem can be added-to or deleted-from the
  64          * sk_storage->list by the bpf_prog or by the bpf-map's syscall.
  65          *
  66          * It is racing with bpf_local_storage_map_free() alone
  67          * when unlinking elem from the sk_storage->list and
  68          * the map's bucket->list.
  69          */
  70         raw_spin_lock_bh(&sk_storage->lock);
  71         hlist_for_each_entry_safe(selem, n, &sk_storage->list, snode) {
  72                 /* Always unlink from map before unlinking from
  73                  * sk_storage.
  74                  */
  75                 bpf_selem_unlink_map(selem);
  76                 free_sk_storage = bpf_selem_unlink_storage_nolock(sk_storage,
  77                                                                   selem, true);
  78         }
  79         raw_spin_unlock_bh(&sk_storage->lock);
  80         rcu_read_unlock();
  81
  82         if (free_sk_storage)
  83                 kfree_rcu(sk_storage, rcu);
  84 }
  85
  86 static void bpf_sk_storage_map_free(struct bpf_map *map)
  87 {
  88         struct bpf_local_storage_map *smap;
  89
  90         smap = (struct bpf_local_storage_map *)map;
  91         bpf_local_storage_cache_idx_free(&sk_cache, smap->cache_idx);
  92         bpf_local_storage_map_free(smap, NULL);
  93 }
  94
  95 static struct bpf_map *bpf_sk_storage_map_alloc(union bpf_attr *attr)
  96 {
  97         struct bpf_local_storage_map *smap;
  98
  99         smap = bpf_local_storage_map_alloc(attr);
 100         if (IS_ERR(smap))
 101                 return ERR_CAST(smap);
 102
 103         smap->cache_idx = bpf_local_storage_cache_idx_get(&sk_cache);
 104         return &smap->map;
 105 }
 106
 107 static int notsupp_get_next_key(struct bpf_map *map, void *key,
 108                                 void *next_key)
 109 {
 110         return -ENOTSUPP;
 111 }
 112
 113 static void *bpf_fd_sk_storage_lookup_elem(struct bpf_map *map, void *key)
 114 {
 115         struct bpf_local_storage_data *sdata;
 116         struct socket *sock;
 117         int fd, err;
 118
 119         fd = *(int *)key;
 120         sock = sockfd_lookup(fd, &err);
 121         if (sock) {
 122                 sdata = bpf_sk_storage_lookup(sock->sk, map, true);
 123                 sockfd_put(sock);
 124                 return sdata ? sdata->data : NULL;
 125         }
 126
 127         return ERR_PTR(err);
 128 }
 129
 130 static int bpf_fd_sk_storage_update_elem(struct bpf_map *map, void *key,
 131                                          void *value, u64 map_flags)
 132 {
 133         struct bpf_local_storage_data *sdata;
 134         struct socket *sock;
 135         int fd, err;
 136
 137         fd = *(int *)key;
 138         sock = sockfd_lookup(fd, &err);
 139         if (sock) {
 140                 sdata = bpf_local_storage_update(
 141                         sock->sk, (struct bpf_local_storage_map *)map, value,
 142                         map_flags);
 143                 sockfd_put(sock);
 144                 return PTR_ERR_OR_ZERO(sdata);
 145         }
 146
 147         return err;
 148 }
 149
 150 static int bpf_fd_sk_storage_delete_elem(struct bpf_map *map, void *key)
 151 {
 152         struct socket *sock;
 153         int fd, err;
 154
 155         fd = *(int *)key;
 156         sock = sockfd_lookup(fd, &err);
 157         if (sock) {
 158                 err = bpf_sk_storage_del(sock->sk, map);
 159                 sockfd_put(sock);
 160                 return err;
 161         }
 162
 163         return err;
 164 }
 165
 166 static struct bpf_local_storage_elem *
 167 bpf_sk_storage_clone_elem(struct sock *newsk,
 168                           struct bpf_local_storage_map *smap,
 169                           struct bpf_local_storage_elem *selem)
 170 {
 171         struct bpf_local_storage_elem *copy_selem;
 172
 173         copy_selem = bpf_selem_alloc(smap, newsk, NULL, true);
 174         if (!copy_selem)
 175                 return NULL;
 176
 177         if (map_value_has_spin_lock(&smap->map))
 178                 copy_map_value_locked(&smap->map, SDATA(copy_selem)->data,
 179                                       SDATA(selem)->data, true);
 180         else
 181                 copy_map_value(&smap->map, SDATA(copy_selem)->data,
 182                                SDATA(selem)->data);
 183
 184         return copy_selem;
 185 }
 186
 187 int bpf_sk_storage_clone(const struct sock *sk, struct sock *newsk)
 188 {
 189         struct bpf_local_storage *new_sk_storage = NULL;
 190         struct bpf_local_storage *sk_storage;
 191         struct bpf_local_storage_elem *selem;
 192         int ret = 0;
 193
 194         RCU_INIT_POINTER(newsk->sk_bpf_storage, NULL);
 195
 196         rcu_read_lock();
 197         sk_storage = rcu_dereference(sk->sk_bpf_storage);
 198
 199         if (!sk_storage || hlist_empty(&sk_storage->list))
 200                 goto out;
 201
 202         hlist_for_each_entry_rcu(selem, &sk_storage->list, snode) {
 203                 struct bpf_local_storage_elem *copy_selem;
 204                 struct bpf_local_storage_map *smap;
 205                 struct bpf_map *map;
 206
 207                 smap = rcu_dereference(SDATA(selem)->smap);
 208                 if (!(smap->map.map_flags & BPF_F_CLONE))
 209                         continue;
 210
 211                 /* Note that for lockless listeners adding new element
 212                  * here can race with cleanup in bpf_local_storage_map_free.
 213                  * Try to grab map refcnt to make sure that it's still
 214                  * alive and prevent concurrent removal.
 215                  */
 216                 map = bpf_map_inc_not_zero(&smap->map);
 217                 if (IS_ERR(map))
 218                         continue;
 219
 220                 copy_selem = bpf_sk_storage_clone_elem(newsk, smap, selem);
 221                 if (!copy_selem) {
 222                         ret = -ENOMEM;
 223                         bpf_map_put(map);
 224                         goto out;
 225                 }
 226
 227                 if (new_sk_storage) {
 228                         bpf_selem_link_map(smap, copy_selem);
 229                         bpf_selem_link_storage_nolock(new_sk_storage, copy_selem);
 230                 } else {
 231                         ret = bpf_local_storage_alloc(newsk, smap, copy_selem);
 232                         if (ret) {
 233                                 kfree(copy_selem);
 234                                 atomic_sub(smap->elem_size,
 235                                            &newsk->sk_omem_alloc);
 236                                 bpf_map_put(map);
 237                                 goto out;
 238                         }
 239
 240                         new_sk_storage =
 241                                 rcu_dereference(copy_selem->local_storage);
 242                 }
 243                 bpf_map_put(map);
 244         }
 245
 246 out:
 247         rcu_read_unlock();
 248
 249         /* In case of an error, don't free anything explicitly here, the
 250          * caller is responsible to call bpf_sk_storage_free.
 251          */
 252
 253         return ret;
 254 }
 255
 256 BPF_CALL_4(bpf_sk_storage_get, struct bpf_map *, map, struct sock *, sk,
 257            void *, value, u64, flags)
 258 {
 259         struct bpf_local_storage_data *sdata;
 260
 261         if (!sk || !sk_fullsock(sk) || flags > BPF_SK_STORAGE_GET_F_CREATE)
 262                 return (unsigned long)NULL;
 263
 264         sdata = bpf_sk_storage_lookup(sk, map, true);
 265         if (sdata)
 266                 return (unsigned long)sdata->data;
 267
 268         if (flags == BPF_SK_STORAGE_GET_F_CREATE &&
 269             /* Cannot add new elem to a going away sk.
 270              * Otherwise, the new elem may become a leak
 271              * (and also other memory issues during map
 272              *  destruction).
 273              */
 274             refcount_inc_not_zero(&sk->sk_refcnt)) {
 275                 sdata = bpf_local_storage_update(
 276                         sk, (struct bpf_local_storage_map *)map, value,
 277                         BPF_NOEXIST);
 278                 /* sk must be a fullsock (guaranteed by verifier),
 279                  * so sock_gen_put() is unnecessary.
 280                  */
 281                 sock_put(sk);
 282                 return IS_ERR(sdata) ?
 283                         (unsigned long)NULL : (unsigned long)sdata->data;
 284         }
 285
 286         return (unsigned long)NULL;
 287 }
 288
 289 BPF_CALL_2(bpf_sk_storage_delete, struct bpf_map *, map, struct sock *, sk)
 290 {
 291         if (!sk || !sk_fullsock(sk))
 292                 return -EINVAL;
 293
 294         if (refcount_inc_not_zero(&sk->sk_refcnt)) {
 295                 int err;
 296
 297                 err = bpf_sk_storage_del(sk, map);
 298                 sock_put(sk);
 299                 return err;
 300         }
 301
 302         return -ENOENT;
 303 }
 304
 305 static int bpf_sk_storage_charge(struct bpf_local_storage_map *smap,
 306                                  void *owner, u32 size)
 307 {
 308         struct sock *sk = (struct sock *)owner;
 309
 310         /* same check as in sock_kmalloc() */
 311         if (size <= sysctl_optmem_max &&
 312             atomic_read(&sk->sk_omem_alloc) + size < sysctl_optmem_max) {
 313                 atomic_add(size, &sk->sk_omem_alloc);
 314                 return 0;
 315         }
 316
 317         return -ENOMEM;
 318 }
 319
 320 static void bpf_sk_storage_uncharge(struct bpf_local_storage_map *smap,
 321                                     void *owner, u32 size)
 322 {
 323         struct sock *sk = owner;
 324
 325         atomic_sub(size, &sk->sk_omem_alloc);
 326 }
 327
 328 static struct bpf_local_storage __rcu **
 329 bpf_sk_storage_ptr(void *owner)
 330 {
 331         struct sock *sk = owner;
 332
 333         return &sk->sk_bpf_storage;
 334 }
 335
 336 static int sk_storage_map_btf_id;
 337 const struct bpf_map_ops sk_storage_map_ops = {
 338         .map_meta_equal = bpf_map_meta_equal,
 339         .map_alloc_check = bpf_local_storage_map_alloc_check,
 340         .map_alloc = bpf_sk_storage_map_alloc,
 341         .map_free = bpf_sk_storage_map_free,
 342         .map_get_next_key = notsupp_get_next_key,
 343         .map_lookup_elem = bpf_fd_sk_storage_lookup_elem,
 344         .map_update_elem = bpf_fd_sk_storage_update_elem,
 345         .map_delete_elem = bpf_fd_sk_storage_delete_elem,
 346         .map_check_btf = bpf_local_storage_map_check_btf,
 347         .map_btf_name = "bpf_local_storage_map",
 348         .map_btf_id = &sk_storage_map_btf_id,
 349         .map_local_storage_charge = bpf_sk_storage_charge,
 350         .map_local_storage_uncharge = bpf_sk_storage_uncharge,
 351         .map_owner_storage_ptr = bpf_sk_storage_ptr,
 352 };
 353
 354 const struct bpf_func_proto bpf_sk_storage_get_proto = {
 355         .func           = bpf_sk_storage_get,
 356         .gpl_only       = false,
 357         .ret_type       = RET_PTR_TO_MAP_VALUE_OR_NULL,
 358         .arg1_type      = ARG_CONST_MAP_PTR,
 359         .arg2_type      = ARG_PTR_TO_BTF_ID_SOCK_COMMON,
 360         .arg3_type      = ARG_PTR_TO_MAP_VALUE_OR_NULL,
 361         .arg4_type      = ARG_ANYTHING,
 362 };
 363
 364 const struct bpf_func_proto bpf_sk_storage_get_cg_sock_proto = {
 365         .func           = bpf_sk_storage_get,
 366         .gpl_only       = false,
 367         .ret_type       = RET_PTR_TO_MAP_VALUE_OR_NULL,
 368         .arg1_type      = ARG_CONST_MAP_PTR,
 369         .arg2_type      = ARG_PTR_TO_CTX, /* context is 'struct sock' */
 370         .arg3_type      = ARG_PTR_TO_MAP_VALUE_OR_NULL,
 371         .arg4_type      = ARG_ANYTHING,
 372 };
 373
 374 const struct bpf_func_proto bpf_sk_storage_delete_proto = {
 375         .func           = bpf_sk_storage_delete,
 376         .gpl_only       = false,
 377         .ret_type       = RET_INTEGER,
 378         .arg1_type      = ARG_CONST_MAP_PTR,
 379         .arg2_type      = ARG_PTR_TO_BTF_ID_SOCK_COMMON,
 380 };
 381
 382 static bool bpf_sk_storage_tracing_allowed(const struct bpf_prog *prog)
 383 {
 384         const struct btf *btf_vmlinux;
 385         const struct btf_type *t;
 386         const char *tname;
 387         u32 btf_id;
 388
 389         if (prog->aux->dst_prog)
 390                 return false;
 391
 392         /* Ensure the tracing program is not tracing
 393          * any bpf_sk_storage*() function and also
 394          * use the bpf_sk_storage_(get|delete) helper.
 395          */
 396         switch (prog->expected_attach_type) {
 397         case BPF_TRACE_ITER:
 398         case BPF_TRACE_RAW_TP:
 399                 /* bpf_sk_storage has no trace point */
 400                 return true;
 401         case BPF_TRACE_FENTRY:
 402         case BPF_TRACE_FEXIT:
 403                 btf_vmlinux = bpf_get_btf_vmlinux();
 404                 btf_id = prog->aux->attach_btf_id;
 405                 t = btf_type_by_id(btf_vmlinux, btf_id);
 406                 tname = btf_name_by_offset(btf_vmlinux, t->name_off);
 407                 return !!strncmp(tname, "bpf_sk_storage",
 408                                  strlen("bpf_sk_storage"));
 409         default:
 410                 return false;
 411         }
 412
 413         return false;
 414 }
 415
 416 BPF_CALL_4(bpf_sk_storage_get_tracing, struct bpf_map *, map, struct sock *, sk,
 417            void *, value, u64, flags)
 418 {
 419         if (in_hardirq() || in_nmi())
 420                 return (unsigned long)NULL;
 421
 422         return (unsigned long)____bpf_sk_storage_get(map, sk, value, flags);
 423 }
 424
 425 BPF_CALL_2(bpf_sk_storage_delete_tracing, struct bpf_map *, map,
 426            struct sock *, sk)
 427 {
 428         if (in_hardirq() || in_nmi())
 429                 return -EPERM;
 430
 431         return ____bpf_sk_storage_delete(map, sk);
 432 }
 433
 434 const struct bpf_func_proto bpf_sk_storage_get_tracing_proto = {
 435         .func           = bpf_sk_storage_get_tracing,
 436         .gpl_only       = false,
 437         .ret_type       = RET_PTR_TO_MAP_VALUE_OR_NULL,
 438         .arg1_type      = ARG_CONST_MAP_PTR,
 439         .arg2_type      = ARG_PTR_TO_BTF_ID,
 440         .arg2_btf_id    = &btf_sock_ids[BTF_SOCK_TYPE_SOCK_COMMON],
 441         .arg3_type      = ARG_PTR_TO_MAP_VALUE_OR_NULL,
 442         .arg4_type      = ARG_ANYTHING,
 443         .allowed        = bpf_sk_storage_tracing_allowed,
 444 };
 445
 446 const struct bpf_func_proto bpf_sk_storage_delete_tracing_proto = {
 447         .func           = bpf_sk_storage_delete_tracing,
 448         .gpl_only       = false,
 449         .ret_type       = RET_INTEGER,
 450         .arg1_type      = ARG_CONST_MAP_PTR,
 451         .arg2_type      = ARG_PTR_TO_BTF_ID,
 452         .arg2_btf_id    = &btf_sock_ids[BTF_SOCK_TYPE_SOCK_COMMON],
 453         .allowed        = bpf_sk_storage_tracing_allowed,
 454 };
 455
 456 struct bpf_sk_storage_diag {
 457         u32 nr_maps;
 458         struct bpf_map *maps[];
 459 };
 460
 461 /* The reply will be like:
 462  * INET_DIAG_BPF_SK_STORAGES (nla_nest)
 463  *      SK_DIAG_BPF_STORAGE (nla_nest)
 464  *              SK_DIAG_BPF_STORAGE_MAP_ID (nla_put_u32)
 465  *              SK_DIAG_BPF_STORAGE_MAP_VALUE (nla_reserve_64bit)
 466  *      SK_DIAG_BPF_STORAGE (nla_nest)
 467  *              SK_DIAG_BPF_STORAGE_MAP_ID (nla_put_u32)
 468  *              SK_DIAG_BPF_STORAGE_MAP_VALUE (nla_reserve_64bit)
 469  *      ....
 470  */
 471 static int nla_value_size(u32 value_size)
 472 {
 473         /* SK_DIAG_BPF_STORAGE (nla_nest)
 474          *      SK_DIAG_BPF_STORAGE_MAP_ID (nla_put_u32)
 475          *      SK_DIAG_BPF_STORAGE_MAP_VALUE (nla_reserve_64bit)
 476          */
 477         return nla_total_size(0) + nla_total_size(sizeof(u32)) +
 478                 nla_total_size_64bit(value_size);
 479 }
 480
 481 void bpf_sk_storage_diag_free(struct bpf_sk_storage_diag *diag)
 482 {
 483         u32 i;
 484
 485         if (!diag)
 486                 return;
 487
 488         for (i = 0; i < diag->nr_maps; i++)
 489                 bpf_map_put(diag->maps[i]);
 490
 491         kfree(diag);
 492 }
 493 EXPORT_SYMBOL_GPL(bpf_sk_storage_diag_free);
 494
 495 static bool diag_check_dup(const struct bpf_sk_storage_diag *diag,
 496                            const struct bpf_map *map)
 497 {
 498         u32 i;
 499
 500         for (i = 0; i < diag->nr_maps; i++) {
 501                 if (diag->maps[i] == map)
 502                         return true;
 503         }
 504
 505         return false;
 506 }
 507
 508 struct bpf_sk_storage_diag *
 509 bpf_sk_storage_diag_alloc(const struct nlattr *nla_stgs)
 510 {
 511         struct bpf_sk_storage_diag *diag;
 512         struct nlattr *nla;
 513         u32 nr_maps = 0;
 514         int rem, err;
 515
 516         /* bpf_local_storage_map is currently limited to CAP_SYS_ADMIN as
 517          * the map_alloc_check() side also does.
 518          */
 519         if (!bpf_capable())
 520                 return ERR_PTR(-EPERM);
 521
 522         nla_for_each_nested(nla, nla_stgs, rem) {
 523                 if (nla_type(nla) == SK_DIAG_BPF_STORAGE_REQ_MAP_FD)
 524                         nr_maps++;
 525         }
 526
 527         diag = kzalloc(struct_size(diag, maps, nr_maps), GFP_KERNEL);
 528         if (!diag)
 529                 return ERR_PTR(-ENOMEM);
 530
 531         nla_for_each_nested(nla, nla_stgs, rem) {
 532                 struct bpf_map *map;
 533                 int map_fd;
 534
 535                 if (nla_type(nla) != SK_DIAG_BPF_STORAGE_REQ_MAP_FD)
 536                         continue;
 537
 538                 map_fd = nla_get_u32(nla);
 539                 map = bpf_map_get(map_fd);
 540                 if (IS_ERR(map)) {
 541                         err = PTR_ERR(map);
 542                         goto err_free;
 543                 }
 544                 if (map->map_type != BPF_MAP_TYPE_SK_STORAGE) {
 545                         bpf_map_put(map);
 546                         err = -EINVAL;
 547                         goto err_free;
 548                 }
 549                 if (diag_check_dup(diag, map)) {
 550                         bpf_map_put(map);
 551                         err = -EEXIST;
 552                         goto err_free;
 553                 }
 554                 diag->maps[diag->nr_maps++] = map;
 555         }
 556
 557         return diag;
 558
 559 err_free:
 560         bpf_sk_storage_diag_free(diag);
 561         return ERR_PTR(err);
 562 }
 563 EXPORT_SYMBOL_GPL(bpf_sk_storage_diag_alloc);
 564
 565 static int diag_get(struct bpf_local_storage_data *sdata, struct sk_buff *skb)
 566 {
 567         struct nlattr *nla_stg, *nla_value;
 568         struct bpf_local_storage_map *smap;
 569
 570         /* It cannot exceed max nlattr's payload */
 571         BUILD_BUG_ON(U16_MAX - NLA_HDRLEN < BPF_LOCAL_STORAGE_MAX_VALUE_SIZE);
 572
 573         nla_stg = nla_nest_start(skb, SK_DIAG_BPF_STORAGE);
 574         if (!nla_stg)
 575                 return -EMSGSIZE;
 576
 577         smap = rcu_dereference(sdata->smap);
 578         if (nla_put_u32(skb, SK_DIAG_BPF_STORAGE_MAP_ID, smap->map.id))
 579                 goto errout;
 580
 581         nla_value = nla_reserve_64bit(skb, SK_DIAG_BPF_STORAGE_MAP_VALUE,
 582                                       smap->map.value_size,
 583                                       SK_DIAG_BPF_STORAGE_PAD);
 584         if (!nla_value)
 585                 goto errout;
 586
 587         if (map_value_has_spin_lock(&smap->map))
 588                 copy_map_value_locked(&smap->map, nla_data(nla_value),
 589                                       sdata->data, true);
 590         else
 591                 copy_map_value(&smap->map, nla_data(nla_value), sdata->data);
 592
 593         nla_nest_end(skb, nla_stg);
 594         return 0;
 595
 596 errout:
 597         nla_nest_cancel(skb, nla_stg);
 598         return -EMSGSIZE;
 599 }
 600
 601 static int bpf_sk_storage_diag_put_all(struct sock *sk, struct sk_buff *skb,
 602                                        int stg_array_type,
 603                                        unsigned int *res_diag_size)
 604 {
 605         /* stg_array_type (e.g. INET_DIAG_BPF_SK_STORAGES) */
 606         unsigned int diag_size = nla_total_size(0);
 607         struct bpf_local_storage *sk_storage;
 608         struct bpf_local_storage_elem *selem;
 609         struct bpf_local_storage_map *smap;
 610         struct nlattr *nla_stgs;
 611         unsigned int saved_len;
 612         int err = 0;
 613
 614         rcu_read_lock();
 615
 616         sk_storage = rcu_dereference(sk->sk_bpf_storage);
 617         if (!sk_storage || hlist_empty(&sk_storage->list)) {
 618                 rcu_read_unlock();
 619                 return 0;
 620         }
 621
 622         nla_stgs = nla_nest_start(skb, stg_array_type);
 623         if (!nla_stgs)
 624                 /* Continue to learn diag_size */
 625                 err = -EMSGSIZE;
 626
 627         saved_len = skb->len;
 628         hlist_for_each_entry_rcu(selem, &sk_storage->list, snode) {
 629                 smap = rcu_dereference(SDATA(selem)->smap);
 630                 diag_size += nla_value_size(smap->map.value_size);
 631
 632                 if (nla_stgs && diag_get(SDATA(selem), skb))
 633                         /* Continue to learn diag_size */
 634                         err = -EMSGSIZE;
 635         }
 636
 637         rcu_read_unlock();
 638
 639         if (nla_stgs) {
 640                 if (saved_len == skb->len)
 641                         nla_nest_cancel(skb, nla_stgs);
 642                 else
 643                         nla_nest_end(skb, nla_stgs);
 644         }
 645
 646         if (diag_size == nla_total_size(0)) {
 647                 *res_diag_size = 0;
 648                 return 0;
 649         }
 650
 651         *res_diag_size = diag_size;
 652         return err;
 653 }
 654
 655 int bpf_sk_storage_diag_put(struct bpf_sk_storage_diag *diag,
 656                             struct sock *sk, struct sk_buff *skb,
 657                             int stg_array_type,
 658                             unsigned int *res_diag_size)
 659 {
 660         /* stg_array_type (e.g. INET_DIAG_BPF_SK_STORAGES) */
 661         unsigned int diag_size = nla_total_size(0);
 662         struct bpf_local_storage *sk_storage;
 663         struct bpf_local_storage_data *sdata;
 664         struct nlattr *nla_stgs;
 665         unsigned int saved_len;
 666         int err = 0;
 667         u32 i;
 668
 669         *res_diag_size = 0;
 670
 671         /* No map has been specified.  Dump all. */
 672         if (!diag->nr_maps)
 673                 return bpf_sk_storage_diag_put_all(sk, skb, stg_array_type,
 674                                                    res_diag_size);
 675
 676         rcu_read_lock();
 677         sk_storage = rcu_dereference(sk->sk_bpf_storage);
 678         if (!sk_storage || hlist_empty(&sk_storage->list)) {
 679                 rcu_read_unlock();
 680                 return 0;
 681         }
 682
 683         nla_stgs = nla_nest_start(skb, stg_array_type);
 684         if (!nla_stgs)
 685                 /* Continue to learn diag_size */
 686                 err = -EMSGSIZE;
 687
 688         saved_len = skb->len;
 689         for (i = 0; i < diag->nr_maps; i++) {
 690                 sdata = bpf_local_storage_lookup(sk_storage,
 691                                 (struct bpf_local_storage_map *)diag->maps[i],
 692                                 false);
 693
 694                 if (!sdata)
 695                         continue;
 696
 697                 diag_size += nla_value_size(diag->maps[i]->value_size);
 698
 699                 if (nla_stgs && diag_get(sdata, skb))
 700                         /* Continue to learn diag_size */
 701                         err = -EMSGSIZE;
 702         }
 703         rcu_read_unlock();
 704
 705         if (nla_stgs) {
 706                 if (saved_len == skb->len)
 707                         nla_nest_cancel(skb, nla_stgs);
 708                 else
 709                         nla_nest_end(skb, nla_stgs);
 710         }
 711
 712         if (diag_size == nla_total_size(0)) {
 713                 *res_diag_size = 0;
 714                 return 0;
 715         }
 716
 717         *res_diag_size = diag_size;
 718         return err;
 719 }
 720 EXPORT_SYMBOL_GPL(bpf_sk_storage_diag_put);
 721
 722 struct bpf_iter_seq_sk_storage_map_info {
 723         struct bpf_map *map;
 724         unsigned int bucket_id;
 725         unsigned skip_elems;
 726 };
 727
 728 static struct bpf_local_storage_elem *
 729 bpf_sk_storage_map_seq_find_next(struct bpf_iter_seq_sk_storage_map_info *info,
 730                                  struct bpf_local_storage_elem *prev_selem)
 731         __acquires(RCU) __releases(RCU)
 732 {
 733         struct bpf_local_storage *sk_storage;
 734         struct bpf_local_storage_elem *selem;
 735         u32 skip_elems = info->skip_elems;
 736         struct bpf_local_storage_map *smap;
 737         u32 bucket_id = info->bucket_id;
 738         u32 i, count, n_buckets;
 739         struct bpf_local_storage_map_bucket *b;
 740
 741         smap = (struct bpf_local_storage_map *)info->map;
 742         n_buckets = 1U << smap->bucket_log;
 743         if (bucket_id >= n_buckets)
 744                 return NULL;
 745
 746         /* try to find next selem in the same bucket */
 747         selem = prev_selem;
 748         count = 0;
 749         while (selem) {
 750                 selem = hlist_entry_safe(rcu_dereference(hlist_next_rcu(&selem->map_node)),
 751                                          struct bpf_local_storage_elem, map_node);
 752                 if (!selem) {
 753                         /* not found, unlock and go to the next bucket */
 754                         b = &smap->buckets[bucket_id++];
 755                         rcu_read_unlock();
 756                         skip_elems = 0;
 757                         break;
 758                 }
 759                 sk_storage = rcu_dereference(selem->local_storage);
 760                 if (sk_storage) {
 761                         info->skip_elems = skip_elems + count;
 762                         return selem;
 763                 }
 764                 count++;
 765         }
 766
 767         for (i = bucket_id; i < (1U << smap->bucket_log); i++) {
 768                 b = &smap->buckets[i];
 769                 rcu_read_lock();
 770                 count = 0;
 771                 hlist_for_each_entry_rcu(selem, &b->list, map_node) {
 772                         sk_storage = rcu_dereference(selem->local_storage);
 773                         if (sk_storage && count >= skip_elems) {
 774                                 info->bucket_id = i;
 775                                 info->skip_elems = count;
 776                                 return selem;
 777                         }
 778                         count++;
 779                 }
 780                 rcu_read_unlock();
 781                 skip_elems = 0;
 782         }
 783
 784         info->bucket_id = i;
 785         info->skip_elems = 0;
 786         return NULL;
 787 }
 788
 789 static void *bpf_sk_storage_map_seq_start(struct seq_file *seq, loff_t *pos)
 790 {
 791         struct bpf_local_storage_elem *selem;
 792
 793         selem = bpf_sk_storage_map_seq_find_next(seq->private, NULL);
 794         if (!selem)
 795                 return NULL;
 796
 797         if (*pos == 0)
 798                 ++*pos;
 799         return selem;
 800 }
 801
 802 static void *bpf_sk_storage_map_seq_next(struct seq_file *seq, void *v,
 803                                          loff_t *pos)
 804 {
 805         struct bpf_iter_seq_sk_storage_map_info *info = seq->private;
 806
 807         ++*pos;
 808         ++info->skip_elems;
 809         return bpf_sk_storage_map_seq_find_next(seq->private, v);
 810 }
 811
 812 struct bpf_iter__bpf_sk_storage_map {
 813         __bpf_md_ptr(struct bpf_iter_meta *, meta);
 814         __bpf_md_ptr(struct bpf_map *, map);
 815         __bpf_md_ptr(struct sock *, sk);
 816         __bpf_md_ptr(void *, value);
 817 };
 818
 819 DEFINE_BPF_ITER_FUNC(bpf_sk_storage_map, struct bpf_iter_meta *meta,
 820                      struct bpf_map *map, struct sock *sk,
 821                      void *value)
 822
 823 static int __bpf_sk_storage_map_seq_show(struct seq_file *seq,
 824                                          struct bpf_local_storage_elem *selem)
 825 {
 826         struct bpf_iter_seq_sk_storage_map_info *info = seq->private;
 827         struct bpf_iter__bpf_sk_storage_map ctx = {};
 828         struct bpf_local_storage *sk_storage;
 829         struct bpf_iter_meta meta;
 830         struct bpf_prog *prog;
 831         int ret = 0;
 832
 833         meta.seq = seq;
 834         prog = bpf_iter_get_info(&meta, selem == NULL);
 835         if (prog) {
 836                 ctx.meta = &meta;
 837                 ctx.map = info->map;
 838                 if (selem) {
 839                         sk_storage = rcu_dereference(selem->local_storage);
 840                         ctx.sk = sk_storage->owner;
 841                         ctx.value = SDATA(selem)->data;
 842                 }
 843                 ret = bpf_iter_run_prog(prog, &ctx);
 844         }
 845
 846         return ret;
 847 }
 848
 849 static int bpf_sk_storage_map_seq_show(struct seq_file *seq, void *v)
 850 {
 851         return __bpf_sk_storage_map_seq_show(seq, v);
 852 }
 853
 854 static void bpf_sk_storage_map_seq_stop(struct seq_file *seq, void *v)
 855         __releases(RCU)
 856 {
 857         if (!v)
 858                 (void)__bpf_sk_storage_map_seq_show(seq, v);
 859         else
 860                 rcu_read_unlock();
 861 }
 862
 863 static int bpf_iter_init_sk_storage_map(void *priv_data,
 864                                         struct bpf_iter_aux_info *aux)
 865 {
 866         struct bpf_iter_seq_sk_storage_map_info *seq_info = priv_data;
 867
 868         seq_info->map = aux->map;
 869         return 0;
 870 }
 871
 872 static int bpf_iter_attach_map(struct bpf_prog *prog,
 873                                union bpf_iter_link_info *linfo,
 874                                struct bpf_iter_aux_info *aux)
 875 {
 876         struct bpf_map *map;
 877         int err = -EINVAL;
 878
 879         if (!linfo->map.map_fd)
 880                 return -EBADF;
 881
 882         map = bpf_map_get_with_uref(linfo->map.map_fd);
 883         if (IS_ERR(map))
 884                 return PTR_ERR(map);
 885
 886         if (map->map_type != BPF_MAP_TYPE_SK_STORAGE)
 887                 goto put_map;
 888
 889         if (prog->aux->max_rdonly_access > map->value_size) {
 890                 err = -EACCES;
 891                 goto put_map;
 892         }
 893
 894         aux->map = map;
 895         return 0;
 896
 897 put_map:
 898         bpf_map_put_with_uref(map);
 899         return err;
 900 }
 901
 902 static void bpf_iter_detach_map(struct bpf_iter_aux_info *aux)
 903 {
 904         bpf_map_put_with_uref(aux->map);
 905 }
 906
 907 static const struct seq_operations bpf_sk_storage_map_seq_ops = {
 908         .start  = bpf_sk_storage_map_seq_start,
 909         .next   = bpf_sk_storage_map_seq_next,
 910         .stop   = bpf_sk_storage_map_seq_stop,
 911         .show   = bpf_sk_storage_map_seq_show,
 912 };
 913
 914 static const struct bpf_iter_seq_info iter_seq_info = {
 915         .seq_ops                = &bpf_sk_storage_map_seq_ops,
 916         .init_seq_private       = bpf_iter_init_sk_storage_map,
 917         .fini_seq_private       = NULL,
 918         .seq_priv_size          = sizeof(struct bpf_iter_seq_sk_storage_map_info),
 919 };
 920
 921 static struct bpf_iter_reg bpf_sk_storage_map_reg_info = {
 922         .target                 = "bpf_sk_storage_map",
 923         .attach_target          = bpf_iter_attach_map,
 924         .detach_target          = bpf_iter_detach_map,
 925         .show_fdinfo            = bpf_iter_map_show_fdinfo,
 926         .fill_link_info         = bpf_iter_map_fill_link_info,
 927         .ctx_arg_info_size      = 2,
 928         .ctx_arg_info           = {
 929                 { offsetof(struct bpf_iter__bpf_sk_storage_map, sk),
 930                   PTR_TO_BTF_ID_OR_NULL },
 931                 { offsetof(struct bpf_iter__bpf_sk_storage_map, value),
 932                   PTR_TO_RDWR_BUF_OR_NULL },
 933         },
 934         .seq_info               = &iter_seq_info,
 935 };
 936
 937 static int __init bpf_sk_storage_map_iter_init(void)
 938 {
 939         bpf_sk_storage_map_reg_info.ctx_arg_info[0].btf_id =
 940                 btf_sock_ids[BTF_SOCK_TYPE_SOCK];
 941         return bpf_iter_reg_target(&bpf_sk_storage_map_reg_info);
 942 }
 943 late_initcall(bpf_sk_storage_map_iter_init);