// SPDX-License-Identifier: GPL-2.0 /* * Copyright (c) 2019 Facebook * Copyright 2020 Google LLC. */ #include #include #include #include #include #include #include #include #include #include #include #include #include DEFINE_BPF_STORAGE_CACHE(inode_cache); static struct bpf_local_storage __rcu ** inode_storage_ptr(void *owner) { struct inode *inode = owner; struct bpf_storage_blob *bsb; bsb = bpf_inode(inode); if (!bsb) return NULL; return &bsb->storage; } static struct bpf_local_storage_data *inode_storage_lookup(struct inode *inode, struct bpf_map *map, bool cacheit_lockit) { struct bpf_local_storage *inode_storage; struct bpf_local_storage_map *smap; struct bpf_storage_blob *bsb; bsb = bpf_inode(inode); if (!bsb) return NULL; inode_storage = rcu_dereference(bsb->storage); if (!inode_storage) return NULL; smap = (struct bpf_local_storage_map *)map; return bpf_local_storage_lookup(inode_storage, smap, cacheit_lockit); } void bpf_inode_storage_free(struct inode *inode) { struct bpf_local_storage_elem *selem; struct bpf_local_storage *local_storage; bool free_inode_storage = false; struct bpf_storage_blob *bsb; struct hlist_node *n; bsb = bpf_inode(inode); if (!bsb) return; rcu_read_lock(); local_storage = rcu_dereference(bsb->storage); if (!local_storage) { rcu_read_unlock(); return; } /* Netiher the bpf_prog nor the bpf-map's syscall * could be modifying the local_storage->list now. * Thus, no elem can be added-to or deleted-from the * local_storage->list by the bpf_prog or by the bpf-map's syscall. * * It is racing with bpf_local_storage_map_free() alone * when unlinking elem from the local_storage->list and * the map's bucket->list. */ raw_spin_lock_bh(&local_storage->lock); hlist_for_each_entry_safe(selem, n, &local_storage->list, snode) { /* Always unlink from map before unlinking from * local_storage. */ bpf_selem_unlink_map(selem); free_inode_storage = bpf_selem_unlink_storage_nolock( local_storage, selem, false); } raw_spin_unlock_bh(&local_storage->lock); rcu_read_unlock(); /* free_inoode_storage should always be true as long as * local_storage->list was non-empty. */ if (free_inode_storage) kfree_rcu(local_storage, rcu); } static void *bpf_fd_inode_storage_lookup_elem(struct bpf_map *map, void *key) { struct bpf_local_storage_data *sdata; struct file *f; int fd; fd = *(int *)key; f = fget_raw(fd); if (!f) return NULL; sdata = inode_storage_lookup(f->f_inode, map, true); fput(f); return sdata ? sdata->data : NULL; } static int bpf_fd_inode_storage_update_elem(struct bpf_map *map, void *key, void *value, u64 map_flags) { struct bpf_local_storage_data *sdata; struct file *f; int fd; fd = *(int *)key; f = fget_raw(fd); if (!f || !inode_storage_ptr(f->f_inode)) return -EBADF; sdata = bpf_local_storage_update(f->f_inode, (struct bpf_local_storage_map *)map, value, map_flags); fput(f); return PTR_ERR_OR_ZERO(sdata); } static int inode_storage_delete(struct inode *inode, struct bpf_map *map) { struct bpf_local_storage_data *sdata; sdata = inode_storage_lookup(inode, map, false); if (!sdata) return -ENOENT; bpf_selem_unlink(SELEM(sdata)); return 0; } static int bpf_fd_inode_storage_delete_elem(struct bpf_map *map, void *key) { struct file *f; int fd, err; fd = *(int *)key; f = fget_raw(fd); if (!f) return -EBADF; err = inode_storage_delete(f->f_inode, map); fput(f); return err; } BPF_CALL_4(bpf_inode_storage_get, struct bpf_map *, map, struct inode *, inode, void *, value, u64, flags) { struct bpf_local_storage_data *sdata; if (flags & ~(BPF_LOCAL_STORAGE_GET_F_CREATE)) return (unsigned long)NULL; /* explicitly check that the inode_storage_ptr is not * NULL as inode_storage_lookup returns NULL in this case and * bpf_local_storage_update expects the owner to have a * valid storage pointer. */ if (!inode || !inode_storage_ptr(inode)) return (unsigned long)NULL; sdata = inode_storage_lookup(inode, map, true); if (sdata) return (unsigned long)sdata->data; /* This helper must only called from where the inode is gurranteed * to have a refcount and cannot be freed. */ if (flags & BPF_LOCAL_STORAGE_GET_F_CREATE) { sdata = bpf_local_storage_update( inode, (struct bpf_local_storage_map *)map, value, BPF_NOEXIST); return IS_ERR(sdata) ? (unsigned long)NULL : (unsigned long)sdata->data; } return (unsigned long)NULL; } BPF_CALL_2(bpf_inode_storage_delete, struct bpf_map *, map, struct inode *, inode) { if (!inode) return -EINVAL; /* This helper must only called from where the inode is gurranteed * to have a refcount and cannot be freed. */ return inode_storage_delete(inode, map); } static int notsupp_get_next_key(struct bpf_map *map, void *key, void *next_key) { return -ENOTSUPP; } static struct bpf_map *inode_storage_map_alloc(union bpf_attr *attr) { struct bpf_local_storage_map *smap; smap = bpf_local_storage_map_alloc(attr); if (IS_ERR(smap)) return ERR_CAST(smap); smap->cache_idx = bpf_local_storage_cache_idx_get(&inode_cache); return &smap->map; } static void inode_storage_map_free(struct bpf_map *map) { struct bpf_local_storage_map *smap; smap = (struct bpf_local_storage_map *)map; bpf_local_storage_cache_idx_free(&inode_cache, smap->cache_idx); bpf_local_storage_map_free(smap); } static int inode_storage_map_btf_id; const struct bpf_map_ops inode_storage_map_ops = { .map_meta_equal = bpf_map_meta_equal, .map_alloc_check = bpf_local_storage_map_alloc_check, .map_alloc = inode_storage_map_alloc, .map_free = inode_storage_map_free, .map_get_next_key = notsupp_get_next_key, .map_lookup_elem = bpf_fd_inode_storage_lookup_elem, .map_update_elem = bpf_fd_inode_storage_update_elem, .map_delete_elem = bpf_fd_inode_storage_delete_elem, .map_check_btf = bpf_local_storage_map_check_btf, .map_btf_name = "bpf_local_storage_map", .map_btf_id = &inode_storage_map_btf_id, .map_owner_storage_ptr = inode_storage_ptr, }; BTF_ID_LIST_SINGLE(bpf_inode_storage_btf_ids, struct, inode) const struct bpf_func_proto bpf_inode_storage_get_proto = { .func = bpf_inode_storage_get, .gpl_only = false, .ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL, .arg1_type = ARG_CONST_MAP_PTR, .arg2_type = ARG_PTR_TO_BTF_ID, .arg2_btf_id = &bpf_inode_storage_btf_ids[0], .arg3_type = ARG_PTR_TO_MAP_VALUE_OR_NULL, .arg4_type = ARG_ANYTHING, }; const struct bpf_func_proto bpf_inode_storage_delete_proto = { .func = bpf_inode_storage_delete, .gpl_only = false, .ret_type = RET_INTEGER, .arg1_type = ARG_CONST_MAP_PTR, .arg2_type = ARG_PTR_TO_BTF_ID, .arg2_btf_id = &bpf_inode_storage_btf_ids[0], };