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