kernel/bpf/bpf_inode_storage.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (c) 2019 Facebook
  * Copyright 2020 Google LLC.
  */

 #include <linux/rculist.h>
 #include <linux/list.h>
 #include <linux/hash.h>
 #include <linux/types.h>
 #include <linux/spinlock.h>
 #include <linux/bpf.h>
 #include <linux/bpf_local_storage.h>
 #include <net/sock.h>
 #include <uapi/linux/sock_diag.h>
 #include <uapi/linux/btf.h>
 #include <linux/bpf_lsm.h>
 #include <linux/btf_ids.h>
 #include <linux/fdtable.h>

 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;
 	}

 	/* Neither 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 ERR_PTR(-EBADF);

 	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)
 		return -EBADF;
 	if (!inode_storage_ptr(f->f_inode)) {
 		fput(f);
 		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 guaranteed
 	 * 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 guaranteed
 	 * 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, NULL);
 }

 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],
 };
	// SPDX-License-Identifier: GPL-2.0
	/*
	* Copyright (c) 2019 Facebook
	* Copyright 2020 Google LLC.
	*/

	#include <linux/rculist.h>
	#include <linux/list.h>
	#include <linux/hash.h>
	#include <linux/types.h>
	#include <linux/spinlock.h>
	#include <linux/bpf.h>
	#include <linux/bpf_local_storage.h>
	#include <net/sock.h>
	#include <uapi/linux/sock_diag.h>
	#include <uapi/linux/btf.h>
	#include <linux/bpf_lsm.h>
	#include <linux/btf_ids.h>
	#include <linux/fdtable.h>

	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;
	}

	/* Neither 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 ERR_PTR(-EBADF);

	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)
	return -EBADF;
	if (!inode_storage_ptr(f->f_inode)) {
	fput(f);
	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 guaranteed
	* 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 guaranteed
	* 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, NULL);
	}

	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],
	};