// 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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/* Netiher 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 gurranteed
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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 gurranteed
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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);
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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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