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         int optmem_max = READ_ONCE(sysctl_optmem_max);
 309         struct sock *sk = (struct sock *)owner;
 310
 311         /* same check as in sock_kmalloc() */
 312         if (size <= optmem_max &&
 313             atomic_read(&sk->sk_omem_alloc) + size < optmem_max) {
 314                 atomic_add(size, &sk->sk_omem_alloc);
 315                 return 0;
 316         }
 317
 318         return -ENOMEM;
 319 }
 320
 321 static void bpf_sk_storage_uncharge(struct bpf_local_storage_map *smap,
 322                                     void *owner, u32 size)
 323 {
 324         struct sock *sk = owner;
 325
 326         atomic_sub(size, &sk->sk_omem_alloc);
 327 }
 328
 329 static struct bpf_local_storage __rcu **
 330 bpf_sk_storage_ptr(void *owner)
 331 {
 332         struct sock *sk = owner;
 333
 334         return &sk->sk_bpf_storage;
 335 }
 336
 337 static int sk_storage_map_btf_id;
 338 const struct bpf_map_ops sk_storage_map_ops = {
 339         .map_meta_equal = bpf_map_meta_equal,
 340         .map_alloc_check = bpf_local_storage_map_alloc_check,
 341         .map_alloc = bpf_sk_storage_map_alloc,
 342         .map_free = bpf_sk_storage_map_free,
 343         .map_get_next_key = notsupp_get_next_key,
 344         .map_lookup_elem = bpf_fd_sk_storage_lookup_elem,
 345         .map_update_elem = bpf_fd_sk_storage_update_elem,
 346         .map_delete_elem = bpf_fd_sk_storage_delete_elem,
 347         .map_check_btf = bpf_local_storage_map_check_btf,
 348         .map_btf_name = "bpf_local_storage_map",
 349         .map_btf_id = &sk_storage_map_btf_id,
 350         .map_local_storage_charge = bpf_sk_storage_charge,
 351         .map_local_storage_uncharge = bpf_sk_storage_uncharge,
 352         .map_owner_storage_ptr = bpf_sk_storage_ptr,
 353 };
 354
 355 const struct bpf_func_proto bpf_sk_storage_get_proto = {
 356         .func           = bpf_sk_storage_get,
 357         .gpl_only       = false,
 358         .ret_type       = RET_PTR_TO_MAP_VALUE_OR_NULL,
 359         .arg1_type      = ARG_CONST_MAP_PTR,
 360         .arg2_type      = ARG_PTR_TO_BTF_ID_SOCK_COMMON,
 361         .arg3_type      = ARG_PTR_TO_MAP_VALUE_OR_NULL,
 362         .arg4_type      = ARG_ANYTHING,
 363 };
 364
 365 const struct bpf_func_proto bpf_sk_storage_get_cg_sock_proto = {
 366         .func           = bpf_sk_storage_get,
 367         .gpl_only       = false,
 368         .ret_type       = RET_PTR_TO_MAP_VALUE_OR_NULL,
 369         .arg1_type      = ARG_CONST_MAP_PTR,
 370         .arg2_type      = ARG_PTR_TO_CTX, /* context is 'struct sock' */
 371         .arg3_type      = ARG_PTR_TO_MAP_VALUE_OR_NULL,
 372         .arg4_type      = ARG_ANYTHING,
 373 };
 374
 375 const struct bpf_func_proto bpf_sk_storage_delete_proto = {
 376         .func           = bpf_sk_storage_delete,
 377         .gpl_only       = false,
 378         .ret_type       = RET_INTEGER,
 379         .arg1_type      = ARG_CONST_MAP_PTR,
 380         .arg2_type      = ARG_PTR_TO_BTF_ID_SOCK_COMMON,
 381 };
 382
 383 static bool bpf_sk_storage_tracing_allowed(const struct bpf_prog *prog)
 384 {
 385         const struct btf *btf_vmlinux;
 386         const struct btf_type *t;
 387         const char *tname;
 388         u32 btf_id;
 389
 390         if (prog->aux->dst_prog)
 391                 return false;
 392
 393         /* Ensure the tracing program is not tracing
 394          * any bpf_sk_storage*() function and also
 395          * use the bpf_sk_storage_(get|delete) helper.
 396          */
 397         switch (prog->expected_attach_type) {
 398         case BPF_TRACE_ITER:
 399         case BPF_TRACE_RAW_TP:
 400                 /* bpf_sk_storage has no trace point */
 401                 return true;
 402         case BPF_TRACE_FENTRY:
 403         case BPF_TRACE_FEXIT:
 404                 btf_vmlinux = bpf_get_btf_vmlinux();
 405                 btf_id = prog->aux->attach_btf_id;
 406                 t = btf_type_by_id(btf_vmlinux, btf_id);
 407                 tname = btf_name_by_offset(btf_vmlinux, t->name_off);
 408                 return !!strncmp(tname, "bpf_sk_storage",
 409                                  strlen("bpf_sk_storage"));
 410         default:
 411                 return false;
 412         }
 413
 414         return false;
 415 }
 416
 417 BPF_CALL_4(bpf_sk_storage_get_tracing, struct bpf_map *, map, struct sock *, sk,
 418            void *, value, u64, flags)
 419 {
 420         if (in_hardirq() || in_nmi())
 421                 return (unsigned long)NULL;
 422
 423         return (unsigned long)____bpf_sk_storage_get(map, sk, value, flags);
 424 }
 425
 426 BPF_CALL_2(bpf_sk_storage_delete_tracing, struct bpf_map *, map,
 427            struct sock *, sk)
 428 {
 429         if (in_hardirq() || in_nmi())
 430                 return -EPERM;
 431
 432         return ____bpf_sk_storage_delete(map, sk);
 433 }
 434
 435 const struct bpf_func_proto bpf_sk_storage_get_tracing_proto = {
 436         .func           = bpf_sk_storage_get_tracing,
 437         .gpl_only       = false,
 438         .ret_type       = RET_PTR_TO_MAP_VALUE_OR_NULL,
 439         .arg1_type      = ARG_CONST_MAP_PTR,
 440         .arg2_type      = ARG_PTR_TO_BTF_ID,
 441         .arg2_btf_id    = &btf_sock_ids[BTF_SOCK_TYPE_SOCK_COMMON],
 442         .arg3_type      = ARG_PTR_TO_MAP_VALUE_OR_NULL,
 443         .arg4_type      = ARG_ANYTHING,
 444         .allowed        = bpf_sk_storage_tracing_allowed,
 445 };
 446
 447 const struct bpf_func_proto bpf_sk_storage_delete_tracing_proto = {
 448         .func           = bpf_sk_storage_delete_tracing,
 449         .gpl_only       = false,
 450         .ret_type       = RET_INTEGER,
 451         .arg1_type      = ARG_CONST_MAP_PTR,
 452         .arg2_type      = ARG_PTR_TO_BTF_ID,
 453         .arg2_btf_id    = &btf_sock_ids[BTF_SOCK_TYPE_SOCK_COMMON],
 454         .allowed        = bpf_sk_storage_tracing_allowed,
 455 };
 456
 457 struct bpf_sk_storage_diag {
 458         u32 nr_maps;
 459         struct bpf_map *maps[];
 460 };
 461
 462 /* The reply will be like:
 463  * INET_DIAG_BPF_SK_STORAGES (nla_nest)
 464  *      SK_DIAG_BPF_STORAGE (nla_nest)
 465  *              SK_DIAG_BPF_STORAGE_MAP_ID (nla_put_u32)
 466  *              SK_DIAG_BPF_STORAGE_MAP_VALUE (nla_reserve_64bit)
 467  *      SK_DIAG_BPF_STORAGE (nla_nest)
 468  *              SK_DIAG_BPF_STORAGE_MAP_ID (nla_put_u32)
 469  *              SK_DIAG_BPF_STORAGE_MAP_VALUE (nla_reserve_64bit)
 470  *      ....
 471  */
 472 static int nla_value_size(u32 value_size)
 473 {
 474         /* SK_DIAG_BPF_STORAGE (nla_nest)
 475          *      SK_DIAG_BPF_STORAGE_MAP_ID (nla_put_u32)
 476          *      SK_DIAG_BPF_STORAGE_MAP_VALUE (nla_reserve_64bit)
 477          */
 478         return nla_total_size(0) + nla_total_size(sizeof(u32)) +
 479                 nla_total_size_64bit(value_size);
 480 }
 481
 482 void bpf_sk_storage_diag_free(struct bpf_sk_storage_diag *diag)
 483 {
 484         u32 i;
 485
 486         if (!diag)
 487                 return;
 488
 489         for (i = 0; i < diag->nr_maps; i++)
 490                 bpf_map_put(diag->maps[i]);
 491
 492         kfree(diag);
 493 }
 494 EXPORT_SYMBOL_GPL(bpf_sk_storage_diag_free);
 495
 496 static bool diag_check_dup(const struct bpf_sk_storage_diag *diag,
 497                            const struct bpf_map *map)
 498 {
 499         u32 i;
 500
 501         for (i = 0; i < diag->nr_maps; i++) {
 502                 if (diag->maps[i] == map)
 503                         return true;
 504         }
 505
 506         return false;
 507 }
 508
 509 struct bpf_sk_storage_diag *
 510 bpf_sk_storage_diag_alloc(const struct nlattr *nla_stgs)
 511 {
 512         struct bpf_sk_storage_diag *diag;
 513         struct nlattr *nla;
 514         u32 nr_maps = 0;
 515         int rem, err;
 516
 517         /* bpf_local_storage_map is currently limited to CAP_SYS_ADMIN as
 518          * the map_alloc_check() side also does.
 519          */
 520         if (!bpf_capable())
 521                 return ERR_PTR(-EPERM);
 522
 523         nla_for_each_nested(nla, nla_stgs, rem) {
 524                 if (nla_type(nla) == SK_DIAG_BPF_STORAGE_REQ_MAP_FD)
 525                         nr_maps++;
 526         }
 527
 528         diag = kzalloc(struct_size(diag, maps, nr_maps), GFP_KERNEL);
 529         if (!diag)
 530                 return ERR_PTR(-ENOMEM);
 531
 532         nla_for_each_nested(nla, nla_stgs, rem) {
 533                 struct bpf_map *map;
 534                 int map_fd;
 535
 536                 if (nla_type(nla) != SK_DIAG_BPF_STORAGE_REQ_MAP_FD)
 537                         continue;
 538
 539                 map_fd = nla_get_u32(nla);
 540                 map = bpf_map_get(map_fd);
 541                 if (IS_ERR(map)) {
 542                         err = PTR_ERR(map);
 543                         goto err_free;
 544                 }
 545                 if (map->map_type != BPF_MAP_TYPE_SK_STORAGE) {
 546                         bpf_map_put(map);
 547                         err = -EINVAL;
 548                         goto err_free;
 549                 }
 550                 if (diag_check_dup(diag, map)) {
 551                         bpf_map_put(map);
 552                         err = -EEXIST;
 553                         goto err_free;
 554                 }
 555                 diag->maps[diag->nr_maps++] = map;
 556         }
 557
 558         return diag;
 559
 560 err_free:
 561         bpf_sk_storage_diag_free(diag);
 562         return ERR_PTR(err);
 563 }
 564 EXPORT_SYMBOL_GPL(bpf_sk_storage_diag_alloc);
 565
 566 static int diag_get(struct bpf_local_storage_data *sdata, struct sk_buff *skb)
 567 {
 568         struct nlattr *nla_stg, *nla_value;
 569         struct bpf_local_storage_map *smap;
 570
 571         /* It cannot exceed max nlattr's payload */
 572         BUILD_BUG_ON(U16_MAX - NLA_HDRLEN < BPF_LOCAL_STORAGE_MAX_VALUE_SIZE);
 573
 574         nla_stg = nla_nest_start(skb, SK_DIAG_BPF_STORAGE);
 575         if (!nla_stg)
 576                 return -EMSGSIZE;
 577
 578         smap = rcu_dereference(sdata->smap);
 579         if (nla_put_u32(skb, SK_DIAG_BPF_STORAGE_MAP_ID, smap->map.id))
 580                 goto errout;
 581
 582         nla_value = nla_reserve_64bit(skb, SK_DIAG_BPF_STORAGE_MAP_VALUE,
 583                                       smap->map.value_size,
 584                                       SK_DIAG_BPF_STORAGE_PAD);
 585         if (!nla_value)
 586                 goto errout;
 587
 588         if (map_value_has_spin_lock(&smap->map))
 589                 copy_map_value_locked(&smap->map, nla_data(nla_value),
 590                                       sdata->data, true);
 591         else
 592                 copy_map_value(&smap->map, nla_data(nla_value), sdata->data);
 593
 594         nla_nest_end(skb, nla_stg);
 595         return 0;
 596
 597 errout:
 598         nla_nest_cancel(skb, nla_stg);
 599         return -EMSGSIZE;
 600 }
 601
 602 static int bpf_sk_storage_diag_put_all(struct sock *sk, struct sk_buff *skb,
 603                                        int stg_array_type,
 604                                        unsigned int *res_diag_size)
 605 {
 606         /* stg_array_type (e.g. INET_DIAG_BPF_SK_STORAGES) */
 607         unsigned int diag_size = nla_total_size(0);
 608         struct bpf_local_storage *sk_storage;
 609         struct bpf_local_storage_elem *selem;
 610         struct bpf_local_storage_map *smap;
 611         struct nlattr *nla_stgs;
 612         unsigned int saved_len;
 613         int err = 0;
 614
 615         rcu_read_lock();
 616
 617         sk_storage = rcu_dereference(sk->sk_bpf_storage);
 618         if (!sk_storage || hlist_empty(&sk_storage->list)) {
 619                 rcu_read_unlock();
 620                 return 0;
 621         }
 622
 623         nla_stgs = nla_nest_start(skb, stg_array_type);
 624         if (!nla_stgs)
 625                 /* Continue to learn diag_size */
 626                 err = -EMSGSIZE;
 627
 628         saved_len = skb->len;
 629         hlist_for_each_entry_rcu(selem, &sk_storage->list, snode) {
 630                 smap = rcu_dereference(SDATA(selem)->smap);
 631                 diag_size += nla_value_size(smap->map.value_size);
 632
 633                 if (nla_stgs && diag_get(SDATA(selem), skb))
 634                         /* Continue to learn diag_size */
 635                         err = -EMSGSIZE;
 636         }
 637
 638         rcu_read_unlock();
 639
 640         if (nla_stgs) {
 641                 if (saved_len == skb->len)
 642                         nla_nest_cancel(skb, nla_stgs);
 643                 else
 644                         nla_nest_end(skb, nla_stgs);
 645         }
 646
 647         if (diag_size == nla_total_size(0)) {
 648                 *res_diag_size = 0;
 649                 return 0;
 650         }
 651
 652         *res_diag_size = diag_size;
 653         return err;
 654 }
 655
 656 int bpf_sk_storage_diag_put(struct bpf_sk_storage_diag *diag,
 657                             struct sock *sk, struct sk_buff *skb,
 658                             int stg_array_type,
 659                             unsigned int *res_diag_size)
 660 {
 661         /* stg_array_type (e.g. INET_DIAG_BPF_SK_STORAGES) */
 662         unsigned int diag_size = nla_total_size(0);
 663         struct bpf_local_storage *sk_storage;
 664         struct bpf_local_storage_data *sdata;
 665         struct nlattr *nla_stgs;
 666         unsigned int saved_len;
 667         int err = 0;
 668         u32 i;
 669
 670         *res_diag_size = 0;
 671
 672         /* No map has been specified.  Dump all. */
 673         if (!diag->nr_maps)
 674                 return bpf_sk_storage_diag_put_all(sk, skb, stg_array_type,
 675                                                    res_diag_size);
 676
 677         rcu_read_lock();
 678         sk_storage = rcu_dereference(sk->sk_bpf_storage);
 679         if (!sk_storage || hlist_empty(&sk_storage->list)) {
 680                 rcu_read_unlock();
 681                 return 0;
 682         }
 683
 684         nla_stgs = nla_nest_start(skb, stg_array_type);
 685         if (!nla_stgs)
 686                 /* Continue to learn diag_size */
 687                 err = -EMSGSIZE;
 688
 689         saved_len = skb->len;
 690         for (i = 0; i < diag->nr_maps; i++) {
 691                 sdata = bpf_local_storage_lookup(sk_storage,
 692                                 (struct bpf_local_storage_map *)diag->maps[i],
 693                                 false);
 694
 695                 if (!sdata)
 696                         continue;
 697
 698                 diag_size += nla_value_size(diag->maps[i]->value_size);
 699
 700                 if (nla_stgs && diag_get(sdata, skb))
 701                         /* Continue to learn diag_size */
 702                         err = -EMSGSIZE;
 703         }
 704         rcu_read_unlock();
 705
 706         if (nla_stgs) {
 707                 if (saved_len == skb->len)
 708                         nla_nest_cancel(skb, nla_stgs);
 709                 else
 710                         nla_nest_end(skb, nla_stgs);
 711         }
 712
 713         if (diag_size == nla_total_size(0)) {
 714                 *res_diag_size = 0;
 715                 return 0;
 716         }
 717
 718         *res_diag_size = diag_size;
 719         return err;
 720 }
 721 EXPORT_SYMBOL_GPL(bpf_sk_storage_diag_put);
 722
 723 struct bpf_iter_seq_sk_storage_map_info {
 724         struct bpf_map *map;
 725         unsigned int bucket_id;
 726         unsigned skip_elems;
 727 };
 728
 729 static struct bpf_local_storage_elem *
 730 bpf_sk_storage_map_seq_find_next(struct bpf_iter_seq_sk_storage_map_info *info,
 731                                  struct bpf_local_storage_elem *prev_selem)
 732         __acquires(RCU) __releases(RCU)
 733 {
 734         struct bpf_local_storage *sk_storage;
 735         struct bpf_local_storage_elem *selem;
 736         u32 skip_elems = info->skip_elems;
 737         struct bpf_local_storage_map *smap;
 738         u32 bucket_id = info->bucket_id;
 739         u32 i, count, n_buckets;
 740         struct bpf_local_storage_map_bucket *b;
 741
 742         smap = (struct bpf_local_storage_map *)info->map;
 743         n_buckets = 1U << smap->bucket_log;
 744         if (bucket_id >= n_buckets)
 745                 return NULL;
 746
 747         /* try to find next selem in the same bucket */
 748         selem = prev_selem;
 749         count = 0;
 750         while (selem) {
 751                 selem = hlist_entry_safe(rcu_dereference(hlist_next_rcu(&selem->map_node)),
 752                                          struct bpf_local_storage_elem, map_node);
 753                 if (!selem) {
 754                         /* not found, unlock and go to the next bucket */
 755                         b = &smap->buckets[bucket_id++];
 756                         rcu_read_unlock();
 757                         skip_elems = 0;
 758                         break;
 759                 }
 760                 sk_storage = rcu_dereference(selem->local_storage);
 761                 if (sk_storage) {
 762                         info->skip_elems = skip_elems + count;
 763                         return selem;
 764                 }
 765                 count++;
 766         }
 767
 768         for (i = bucket_id; i < (1U << smap->bucket_log); i++) {
 769                 b = &smap->buckets[i];
 770                 rcu_read_lock();
 771                 count = 0;
 772                 hlist_for_each_entry_rcu(selem, &b->list, map_node) {
 773                         sk_storage = rcu_dereference(selem->local_storage);
 774                         if (sk_storage && count >= skip_elems) {
 775                                 info->bucket_id = i;
 776                                 info->skip_elems = count;
 777                                 return selem;
 778                         }
 779                         count++;
 780                 }
 781                 rcu_read_unlock();
 782                 skip_elems = 0;
 783         }
 784
 785         info->bucket_id = i;
 786         info->skip_elems = 0;
 787         return NULL;
 788 }
 789
 790 static void *bpf_sk_storage_map_seq_start(struct seq_file *seq, loff_t *pos)
 791 {
 792         struct bpf_local_storage_elem *selem;
 793
 794         selem = bpf_sk_storage_map_seq_find_next(seq->private, NULL);
 795         if (!selem)
 796                 return NULL;
 797
 798         if (*pos == 0)
 799                 ++*pos;
 800         return selem;
 801 }
 802
 803 static void *bpf_sk_storage_map_seq_next(struct seq_file *seq, void *v,
 804                                          loff_t *pos)
 805 {
 806         struct bpf_iter_seq_sk_storage_map_info *info = seq->private;
 807
 808         ++*pos;
 809         ++info->skip_elems;
 810         return bpf_sk_storage_map_seq_find_next(seq->private, v);
 811 }
 812
 813 struct bpf_iter__bpf_sk_storage_map {
 814         __bpf_md_ptr(struct bpf_iter_meta *, meta);
 815         __bpf_md_ptr(struct bpf_map *, map);
 816         __bpf_md_ptr(struct sock *, sk);
 817         __bpf_md_ptr(void *, value);
 818 };
 819
 820 DEFINE_BPF_ITER_FUNC(bpf_sk_storage_map, struct bpf_iter_meta *meta,
 821                      struct bpf_map *map, struct sock *sk,
 822                      void *value)
 823
 824 static int __bpf_sk_storage_map_seq_show(struct seq_file *seq,
 825                                          struct bpf_local_storage_elem *selem)
 826 {
 827         struct bpf_iter_seq_sk_storage_map_info *info = seq->private;
 828         struct bpf_iter__bpf_sk_storage_map ctx = {};
 829         struct bpf_local_storage *sk_storage;
 830         struct bpf_iter_meta meta;
 831         struct bpf_prog *prog;
 832         int ret = 0;
 833
 834         meta.seq = seq;
 835         prog = bpf_iter_get_info(&meta, selem == NULL);
 836         if (prog) {
 837                 ctx.meta = &meta;
 838                 ctx.map = info->map;
 839                 if (selem) {
 840                         sk_storage = rcu_dereference(selem->local_storage);
 841                         ctx.sk = sk_storage->owner;
 842                         ctx.value = SDATA(selem)->data;
 843                 }
 844                 ret = bpf_iter_run_prog(prog, &ctx);
 845         }
 846
 847         return ret;
 848 }
 849
 850 static int bpf_sk_storage_map_seq_show(struct seq_file *seq, void *v)
 851 {
 852         return __bpf_sk_storage_map_seq_show(seq, v);
 853 }
 854
 855 static void bpf_sk_storage_map_seq_stop(struct seq_file *seq, void *v)
 856         __releases(RCU)
 857 {
 858         if (!v)
 859                 (void)__bpf_sk_storage_map_seq_show(seq, v);
 860         else
 861                 rcu_read_unlock();
 862 }
 863
 864 static int bpf_iter_init_sk_storage_map(void *priv_data,
 865                                         struct bpf_iter_aux_info *aux)
 866 {
 867         struct bpf_iter_seq_sk_storage_map_info *seq_info = priv_data;
 868
 869         bpf_map_inc_with_uref(aux->map);
 870         seq_info->map = aux->map;
 871         return 0;
 872 }
 873
 874 static void bpf_iter_fini_sk_storage_map(void *priv_data)
 875 {
 876         struct bpf_iter_seq_sk_storage_map_info *seq_info = priv_data;
 877
 878         bpf_map_put_with_uref(seq_info->map);
 879 }
 880
 881 static int bpf_iter_attach_map(struct bpf_prog *prog,
 882                                union bpf_iter_link_info *linfo,
 883                                struct bpf_iter_aux_info *aux)
 884 {
 885         struct bpf_map *map;
 886         int err = -EINVAL;
 887
 888         if (!linfo->map.map_fd)
 889                 return -EBADF;
 890
 891         map = bpf_map_get_with_uref(linfo->map.map_fd);
 892         if (IS_ERR(map))
 893                 return PTR_ERR(map);
 894
 895         if (map->map_type != BPF_MAP_TYPE_SK_STORAGE)
 896                 goto put_map;
 897
 898         if (prog->aux->max_rdwr_access > map->value_size) {
 899                 err = -EACCES;
 900                 goto put_map;
 901         }
 902
 903         aux->map = map;
 904         return 0;
 905
 906 put_map:
 907         bpf_map_put_with_uref(map);
 908         return err;
 909 }
 910
 911 static void bpf_iter_detach_map(struct bpf_iter_aux_info *aux)
 912 {
 913         bpf_map_put_with_uref(aux->map);
 914 }
 915
 916 static const struct seq_operations bpf_sk_storage_map_seq_ops = {
 917         .start  = bpf_sk_storage_map_seq_start,
 918         .next   = bpf_sk_storage_map_seq_next,
 919         .stop   = bpf_sk_storage_map_seq_stop,
 920         .show   = bpf_sk_storage_map_seq_show,
 921 };
 922
 923 static const struct bpf_iter_seq_info iter_seq_info = {
 924         .seq_ops                = &bpf_sk_storage_map_seq_ops,
 925         .init_seq_private       = bpf_iter_init_sk_storage_map,
 926         .fini_seq_private       = bpf_iter_fini_sk_storage_map,
 927         .seq_priv_size          = sizeof(struct bpf_iter_seq_sk_storage_map_info),
 928 };
 929
 930 static struct bpf_iter_reg bpf_sk_storage_map_reg_info = {
 931         .target                 = "bpf_sk_storage_map",
 932         .attach_target          = bpf_iter_attach_map,
 933         .detach_target          = bpf_iter_detach_map,
 934         .show_fdinfo            = bpf_iter_map_show_fdinfo,
 935         .fill_link_info         = bpf_iter_map_fill_link_info,
 936         .ctx_arg_info_size      = 2,
 937         .ctx_arg_info           = {
 938                 { offsetof(struct bpf_iter__bpf_sk_storage_map, sk),
 939                   PTR_TO_BTF_ID_OR_NULL },
 940                 { offsetof(struct bpf_iter__bpf_sk_storage_map, value),
 941                   PTR_TO_BUF | PTR_MAYBE_NULL },
 942         },
 943         .seq_info               = &iter_seq_info,
 944 };
 945
 946 static int __init bpf_sk_storage_map_iter_init(void)
 947 {
 948         bpf_sk_storage_map_reg_info.ctx_arg_info[0].btf_id =
 949                 btf_sock_ids[BTF_SOCK_TYPE_SOCK];
 950         return bpf_iter_reg_target(&bpf_sk_storage_map_reg_info);
 951 }
 952 late_initcall(bpf_sk_storage_map_iter_init);