Re: [PATCH bpf-next 2/5] bpf: Implement cgroup storage available to non-cgroup-attached bpf progs

[sdf@google.com]

On 10/13, Yonghong Song wrote:
> Similar to sk/inode/task storage, implement similar cgroup local storage.

> There already exists a local storage implementation for cgroup-attached
> bpf programs.  See map type BPF_MAP_TYPE_CGROUP_STORAGE and helper
> bpf_get_local_storage(). But there are use cases such that non-cgroup
> attached bpf progs wants to access cgroup local storage data. For example,
> tc egress prog has access to sk and cgroup. It is possible to use
> sk local storage to emulate cgroup local storage by storing data in  
> socket.
> But this is a waste as it could be lots of sockets belonging to a  
> particular
> cgroup. Alternatively, a separate map can be created with cgroup id as  
> the key.
> But this will introduce additional overhead to manipulate the new map.
> A cgroup local storage, similar to existing sk/inode/task storage,
> should help for this use case.

> The life-cycle of storage is managed with the life-cycle of the
> cgroup struct.  i.e. the storage is destroyed along with the owning cgroup
> with a callback to the bpf_cgroup_storage_free when cgroup itself
> is deleted.

> The userspace map operations can be done by using a cgroup fd as a key
> passed to the lookup, update and delete operations.


[..]

> Since map name BPF_MAP_TYPE_CGROUP_STORAGE has been used for old cgroup  
> local
> storage support, the new map name BPF_MAP_TYPE_CGROUP_LOCAL_STORAGE is  
> used
> for cgroup storage available to non-cgroup-attached bpf programs. The two
> helpers are named as bpf_cgroup_local_storage_get() and
> bpf_cgroup_local_storage_delete().

Have you considered doing something similar to 7d9c3427894f ("bpf: Make
cgroup storages shared between programs on the same cgroup") where
the map changes its behavior depending on the key size (see key_size checks
in cgroup_storage_map_alloc)? Looks like sizeof(int) for fd still
can be used so we can, in theory, reuse the name..

Pros:
- no need for a new map name

Cons:
- existing BPF_MAP_TYPE_CGROUP_STORAGE is already messy; might be not a
   good idea to add more stuff to it?

But, for the very least, should we also extend
Documentation/bpf/map_cgroup_storage.rst to cover the new map? We've
tried to keep some of the important details in there..

> Signed-off-by: Yonghong Song <yhs@fb.com>
> ---
>   include/linux/bpf.h             |   3 +
>   include/linux/bpf_types.h       |   1 +
>   include/linux/cgroup-defs.h     |   4 +
>   include/uapi/linux/bpf.h        |  39 +++++
>   kernel/bpf/Makefile             |   2 +-
>   kernel/bpf/bpf_cgroup_storage.c | 280 ++++++++++++++++++++++++++++++++
>   kernel/bpf/helpers.c            |   6 +
>   kernel/bpf/syscall.c            |   3 +-
>   kernel/bpf/verifier.c           |  14 +-
>   kernel/cgroup/cgroup.c          |   4 +
>   kernel/trace/bpf_trace.c        |   4 +
>   scripts/bpf_doc.py              |   2 +
>   tools/include/uapi/linux/bpf.h  |  39 +++++
>   13 files changed, 398 insertions(+), 3 deletions(-)
>   create mode 100644 kernel/bpf/bpf_cgroup_storage.c

> diff --git a/include/linux/bpf.h b/include/linux/bpf.h
> index 9e7d46d16032..1395a01c7f18 100644
> --- a/include/linux/bpf.h
> +++ b/include/linux/bpf.h
> @@ -2045,6 +2045,7 @@ struct bpf_link *bpf_link_by_id(u32 id);

>   const struct bpf_func_proto *bpf_base_func_proto(enum bpf_func_id  
> func_id);
>   void bpf_task_storage_free(struct task_struct *task);
> +void bpf_local_cgroup_storage_free(struct cgroup *cgroup);
>   bool bpf_prog_has_kfunc_call(const struct bpf_prog *prog);
>   const struct btf_func_model *
>   bpf_jit_find_kfunc_model(const struct bpf_prog *prog,
> @@ -2537,6 +2538,8 @@ extern const struct bpf_func_proto  
> bpf_copy_from_user_task_proto;
>   extern const struct bpf_func_proto bpf_set_retval_proto;
>   extern const struct bpf_func_proto bpf_get_retval_proto;
>   extern const struct bpf_func_proto bpf_user_ringbuf_drain_proto;
> +extern const struct bpf_func_proto bpf_cgroup_storage_get_proto;
> +extern const struct bpf_func_proto bpf_cgroup_storage_delete_proto;

>   const struct bpf_func_proto *tracing_prog_func_proto(
>     enum bpf_func_id func_id, const struct bpf_prog *prog);
> diff --git a/include/linux/bpf_types.h b/include/linux/bpf_types.h
> index 2c6a4f2562a7..7a0362d7a0aa 100644
> --- a/include/linux/bpf_types.h
> +++ b/include/linux/bpf_types.h
> @@ -90,6 +90,7 @@ BPF_MAP_TYPE(BPF_MAP_TYPE_CGROUP_ARRAY,  
> cgroup_array_map_ops)
>   #ifdef CONFIG_CGROUP_BPF
>   BPF_MAP_TYPE(BPF_MAP_TYPE_CGROUP_STORAGE, cgroup_storage_map_ops)
>   BPF_MAP_TYPE(BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE, cgroup_storage_map_ops)
> +BPF_MAP_TYPE(BPF_MAP_TYPE_CGROUP_LOCAL_STORAGE,  
> cgroup_local_storage_map_ops)
>   #endif
>   BPF_MAP_TYPE(BPF_MAP_TYPE_HASH, htab_map_ops)
>   BPF_MAP_TYPE(BPF_MAP_TYPE_PERCPU_HASH, htab_percpu_map_ops)
> diff --git a/include/linux/cgroup-defs.h b/include/linux/cgroup-defs.h
> index 4bcf56b3491c..c6f4590dda68 100644
> --- a/include/linux/cgroup-defs.h
> +++ b/include/linux/cgroup-defs.h
> @@ -504,6 +504,10 @@ struct cgroup {
>   	/* Used to store internal freezer state */
>   	struct cgroup_freezer_state freezer;

> +#ifdef CONFIG_BPF_SYSCALL
> +	struct bpf_local_storage __rcu  *bpf_cgroup_storage;
> +#endif
> +
>   	/* ids of the ancestors at each level including self */
>   	u64 ancestor_ids[];
>   };
> diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> index 17f61338f8f8..d918b4054297 100644
> --- a/include/uapi/linux/bpf.h
> +++ b/include/uapi/linux/bpf.h
> @@ -935,6 +935,7 @@ enum bpf_map_type {
>   	BPF_MAP_TYPE_TASK_STORAGE,
>   	BPF_MAP_TYPE_BLOOM_FILTER,
>   	BPF_MAP_TYPE_USER_RINGBUF,
> +	BPF_MAP_TYPE_CGROUP_LOCAL_STORAGE,
>   };

>   /* Note that tracing related programs such as
> @@ -5435,6 +5436,42 @@ union bpf_attr {
>    *		**-E2BIG** if user-space has tried to publish a sample which is
>    *		larger than the size of the ring buffer, or which cannot fit
>    *		within a struct bpf_dynptr.
> + *
> + * void *bpf_cgroup_local_storage_get(struct bpf_map *map, struct cgroup  
> *cgroup, void *value, u64 flags)
> + *	Description
> + *		Get a bpf_local_storage from the *cgroup*.
> + *
> + *		Logically, it could be thought of as getting the value from
> + *		a *map* with *cgroup* as the **key**.  From this
> + *		perspective,  the usage is not much different from
> + *		**bpf_map_lookup_elem**\ (*map*, **&**\ *cgroup*) except this
> + *		helper enforces the key must be a cgroup struct and the map must also
> + *		be a **BPF_MAP_TYPE_CGROUP_LOCAL_STORAGE**.
> + *
> + *		Underneath, the value is stored locally at *cgroup* instead of
> + *		the *map*.  The *map* is used as the bpf-local-storage
> + *		"type". The bpf-local-storage "type" (i.e. the *map*) is
> + *		searched against all bpf_local_storage residing at *cgroup*.
> + *
> + *		An optional *flags* (**BPF_LOCAL_STORAGE_GET_F_CREATE**) can be
> + *		used such that a new bpf_local_storage will be
> + *		created if one does not exist.  *value* can be used
> + *		together with **BPF_LOCAL_STORAGE_GET_F_CREATE** to specify
> + *		the initial value of a bpf_local_storage.  If *value* is
> + *		**NULL**, the new bpf_local_storage will be zero initialized.
> + *	Return
> + *		A bpf_local_storage pointer is returned on success.
> + *
> + *		**NULL** if not found or there was an error in adding
> + *		a new bpf_local_storage.
> + *
> + * long bpf_cgroup_local_storage_delete(struct bpf_map *map, struct  
> cgroup *cgroup)
> + *	Description
> + *		Delete a bpf_local_storage from a *cgroup*.
> + *	Return
> + *		0 on success.
> + *
> + *		**-ENOENT** if the bpf_local_storage cannot be found.
>    */
>   #define ___BPF_FUNC_MAPPER(FN, ctx...)			\
>   	FN(unspec, 0, ##ctx)				\
> @@ -5647,6 +5684,8 @@ union bpf_attr {
>   	FN(tcp_raw_check_syncookie_ipv6, 207, ##ctx)	\
>   	FN(ktime_get_tai_ns, 208, ##ctx)		\
>   	FN(user_ringbuf_drain, 209, ##ctx)		\
> +	FN(cgroup_local_storage_get, 210, ##ctx)	\
> +	FN(cgroup_local_storage_delete, 211, ##ctx)	\
>   	/* */

>   /* backwards-compatibility macros for users of __BPF_FUNC_MAPPER that  
> don't
> diff --git a/kernel/bpf/Makefile b/kernel/bpf/Makefile
> index 341c94f208f4..b02693f51978 100644
> --- a/kernel/bpf/Makefile
> +++ b/kernel/bpf/Makefile
> @@ -25,7 +25,7 @@ ifeq ($(CONFIG_PERF_EVENTS),y)
>   obj-$(CONFIG_BPF_SYSCALL) += stackmap.o
>   endif
>   ifeq ($(CONFIG_CGROUPS),y)
> -obj-$(CONFIG_BPF_SYSCALL) += cgroup_iter.o
> +obj-$(CONFIG_BPF_SYSCALL) += cgroup_iter.o bpf_cgroup_storage.o
>   endif
>   obj-$(CONFIG_CGROUP_BPF) += cgroup.o
>   ifeq ($(CONFIG_INET),y)
> diff --git a/kernel/bpf/bpf_cgroup_storage.c  
> b/kernel/bpf/bpf_cgroup_storage.c
> new file mode 100644
> index 000000000000..9974784822da
> --- /dev/null
> +++ b/kernel/bpf/bpf_cgroup_storage.c
> @@ -0,0 +1,280 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (c) 2022 Meta Platforms, Inc. and affiliates.
> + */
> +
> +#include <linux/types.h>
> +#include <linux/bpf.h>
> +#include <linux/bpf_local_storage.h>
> +#include <uapi/linux/btf.h>
> +#include <linux/btf_ids.h>
> +
> +DEFINE_BPF_STORAGE_CACHE(cgroup_cache);
> +
> +static DEFINE_PER_CPU(int, bpf_cgroup_storage_busy);
> +
> +static void bpf_cgroup_storage_lock(void)
> +{
> +	migrate_disable();
> +	this_cpu_inc(bpf_cgroup_storage_busy);
> +}
> +
> +static void bpf_cgroup_storage_unlock(void)
> +{
> +	this_cpu_dec(bpf_cgroup_storage_busy);
> +	migrate_enable();
> +}
> +
> +static bool bpf_cgroup_storage_trylock(void)
> +{
> +	migrate_disable();
> +	if (unlikely(this_cpu_inc_return(bpf_cgroup_storage_busy) != 1)) {
> +		this_cpu_dec(bpf_cgroup_storage_busy);
> +		migrate_enable();
> +		return false;
> +	}
> +	return true;
> +}

Task storage has lock/unlock/trylock; inode storage doesn't; why does
cgroup need it as well?

> +static struct bpf_local_storage __rcu **cgroup_storage_ptr(void *owner)
> +{
> +	struct cgroup *cg = owner;
> +
> +	return &cg->bpf_cgroup_storage;
> +}
> +
> +void bpf_local_cgroup_storage_free(struct cgroup *cgroup)
> +{
> +	struct bpf_local_storage *local_storage;
> +	struct bpf_local_storage_elem *selem;
> +	bool free_cgroup_storage = false;
> +	struct hlist_node *n;
> +	unsigned long flags;
> +
> +	rcu_read_lock();
> +	local_storage = rcu_dereference(cgroup->bpf_cgroup_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.
> +	 */
> +	bpf_cgroup_storage_lock();
> +	raw_spin_lock_irqsave(&local_storage->lock, flags);
> +	hlist_for_each_entry_safe(selem, n, &local_storage->list, snode) {
> +		bpf_selem_unlink_map(selem);
> +		free_cgroup_storage =
> +			bpf_selem_unlink_storage_nolock(local_storage, selem, false, false);
> +	}
> +	raw_spin_unlock_irqrestore(&local_storage->lock, flags);
> +	bpf_cgroup_storage_unlock();
> +	rcu_read_unlock();
> +
> +	/* free_cgroup_storage should always be true as long as
> +	 * local_storage->list was non-empty.
> +	 */
> +	if (free_cgroup_storage)
> +		kfree_rcu(local_storage, rcu);
> +}

> +static struct bpf_local_storage_data *
> +cgroup_storage_lookup(struct cgroup *cgroup, struct bpf_map *map, bool  
> cacheit_lockit)
> +{
> +	struct bpf_local_storage *cgroup_storage;
> +	struct bpf_local_storage_map *smap;
> +
> +	cgroup_storage = rcu_dereference_check(cgroup->bpf_cgroup_storage,
> +					       bpf_rcu_lock_held());
> +	if (!cgroup_storage)
> +		return NULL;
> +
> +	smap = (struct bpf_local_storage_map *)map;
> +	return bpf_local_storage_lookup(cgroup_storage, smap, cacheit_lockit);
> +}
> +
> +static void *bpf_cgroup_storage_lookup_elem(struct bpf_map *map, void  
> *key)
> +{
> +	struct bpf_local_storage_data *sdata;
> +	struct cgroup *cgroup;
> +	int fd;
> +
> +	fd = *(int *)key;
> +	cgroup = cgroup_get_from_fd(fd);
> +	if (IS_ERR(cgroup))
> +		return ERR_CAST(cgroup);
> +
> +	bpf_cgroup_storage_lock();
> +	sdata = cgroup_storage_lookup(cgroup, map, true);
> +	bpf_cgroup_storage_unlock();
> +	cgroup_put(cgroup);
> +	return sdata ? sdata->data : NULL;
> +}

A lot of the above (free/lookup) seems to be copy-pasted from the task  
storage;
any point in trying to generalize the common parts?

> +static int bpf_cgroup_storage_update_elem(struct bpf_map *map, void *key,
> +					  void *value, u64 map_flags)
> +{
> +	struct bpf_local_storage_data *sdata;
> +	struct cgroup *cgroup;
> +	int err, fd;
> +
> +	fd = *(int *)key;
> +	cgroup = cgroup_get_from_fd(fd);
> +	if (IS_ERR(cgroup))
> +		return PTR_ERR(cgroup);
> +
> +	bpf_cgroup_storage_lock();
> +	sdata = bpf_local_storage_update(cgroup, (struct bpf_local_storage_map  
> *)map,
> +					 value, map_flags, GFP_ATOMIC);
> +	bpf_cgroup_storage_unlock();
> +	err = PTR_ERR_OR_ZERO(sdata);
> +	cgroup_put(cgroup);
> +	return err;
> +}
> +
> +static int cgroup_storage_delete(struct cgroup *cgroup, struct bpf_map  
> *map)
> +{
> +	struct bpf_local_storage_data *sdata;
> +
> +	sdata = cgroup_storage_lookup(cgroup, map, false);
> +	if (!sdata)
> +		return -ENOENT;
> +
> +	bpf_selem_unlink(SELEM(sdata), true);
> +	return 0;
> +}
> +
> +static int bpf_cgroup_storage_delete_elem(struct bpf_map *map, void *key)
> +{
> +	struct cgroup *cgroup;
> +	int err, fd;
> +
> +	fd = *(int *)key;
> +	cgroup = cgroup_get_from_fd(fd);
> +	if (IS_ERR(cgroup))
> +		return PTR_ERR(cgroup);
> +
> +	bpf_cgroup_storage_lock();
> +	err = cgroup_storage_delete(cgroup, map);
> +	bpf_cgroup_storage_unlock();
> +	if (err)
> +		return err;
> +
> +	cgroup_put(cgroup);
> +	return 0;
> +}
> +
> +static int notsupp_get_next_key(struct bpf_map *map, void *key, void  
> *next_key)
> +{
> +	return -ENOTSUPP;
> +}
> +
> +static struct bpf_map *cgroup_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(&cgroup_cache);
> +	return &smap->map;
> +}
> +
> +static void cgroup_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(&cgroup_cache, smap->cache_idx);
> +	bpf_local_storage_map_free(smap, NULL);
> +}
> +
> +/* *gfp_flags* is a hidden argument provided by the verifier */
> +BPF_CALL_5(bpf_cgroup_storage_get, struct bpf_map *, map, struct cgroup  
> *, cgroup,
> +	   void *, value, u64, flags, gfp_t, gfp_flags)
> +{
> +	struct bpf_local_storage_data *sdata;
> +
> +	WARN_ON_ONCE(!bpf_rcu_lock_held());
> +	if (flags & ~(BPF_LOCAL_STORAGE_GET_F_CREATE))
> +		return (unsigned long)NULL;
> +
> +	if (!cgroup)
> +		return (unsigned long)NULL;
> +
> +	if (!bpf_cgroup_storage_trylock())
> +		return (unsigned long)NULL;
> +
> +	sdata = cgroup_storage_lookup(cgroup, map, true);
> +	if (sdata)
> +		goto unlock;
> +
> +	/* only allocate new storage, when the cgroup is refcounted */
> +	if (!percpu_ref_is_dying(&cgroup->self.refcnt) &&
> +	    (flags & BPF_LOCAL_STORAGE_GET_F_CREATE))
> +		sdata = bpf_local_storage_update(cgroup, (struct bpf_local_storage_map  
> *)map,
> +						 value, BPF_NOEXIST, gfp_flags);
> +
> +unlock:
> +	bpf_cgroup_storage_unlock();
> +	return IS_ERR_OR_NULL(sdata) ? (unsigned long)NULL : (unsigned  
> long)sdata->data;
> +}
> +
> +BPF_CALL_2(bpf_cgroup_storage_delete, struct bpf_map *, map, struct  
> cgroup *, cgroup)
> +{
> +	int ret;
> +
> +	WARN_ON_ONCE(!bpf_rcu_lock_held());
> +	if (!cgroup)
> +		return -EINVAL;
> +
> +	if (!bpf_cgroup_storage_trylock())
> +		return -EBUSY;
> +
> +	ret = cgroup_storage_delete(cgroup, map);
> +	bpf_cgroup_storage_unlock();
> +	return ret;
> +}
> +
> +BTF_ID_LIST_SINGLE(cgroup_storage_map_btf_ids, struct,  
> bpf_local_storage_map)
> +const struct bpf_map_ops cgroup_local_storage_map_ops = {
> +	.map_meta_equal = bpf_map_meta_equal,
> +	.map_alloc_check = bpf_local_storage_map_alloc_check,
> +	.map_alloc = cgroup_storage_map_alloc,
> +	.map_free = cgroup_storage_map_free,
> +	.map_get_next_key = notsupp_get_next_key,
> +	.map_lookup_elem = bpf_cgroup_storage_lookup_elem,
> +	.map_update_elem = bpf_cgroup_storage_update_elem,
> +	.map_delete_elem = bpf_cgroup_storage_delete_elem,
> +	.map_check_btf = bpf_local_storage_map_check_btf,
> +	.map_btf_id = &cgroup_storage_map_btf_ids[0],
> +	.map_owner_storage_ptr = cgroup_storage_ptr,
> +};
> +
> +const struct bpf_func_proto bpf_cgroup_storage_get_proto = {
> +	.func		= bpf_cgroup_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_cgroup_btf_id[0],
> +	.arg3_type	= ARG_PTR_TO_MAP_VALUE_OR_NULL,
> +	.arg4_type	= ARG_ANYTHING,
> +};
> +
> +const struct bpf_func_proto bpf_cgroup_storage_delete_proto = {
> +	.func		= bpf_cgroup_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_cgroup_btf_id[0],
> +};
> diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
> index a6b04faed282..5c5bb08832ec 100644
> --- a/kernel/bpf/helpers.c
> +++ b/kernel/bpf/helpers.c
> @@ -1663,6 +1663,12 @@ bpf_base_func_proto(enum bpf_func_id func_id)
>   		return &bpf_dynptr_write_proto;
>   	case BPF_FUNC_dynptr_data:
>   		return &bpf_dynptr_data_proto;
> +#ifdef CONFIG_CGROUPS
> +	case BPF_FUNC_cgroup_local_storage_get:
> +		return &bpf_cgroup_storage_get_proto;
> +	case BPF_FUNC_cgroup_local_storage_delete:
> +		return &bpf_cgroup_storage_delete_proto;
> +#endif
>   	default:
>   		break;
>   	}
> diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
> index 7b373a5e861f..e53c7fae6e22 100644
> --- a/kernel/bpf/syscall.c
> +++ b/kernel/bpf/syscall.c
> @@ -1016,7 +1016,8 @@ static int map_check_btf(struct bpf_map *map, const  
> struct btf *btf,
>   		    map->map_type != BPF_MAP_TYPE_CGROUP_STORAGE &&
>   		    map->map_type != BPF_MAP_TYPE_SK_STORAGE &&
>   		    map->map_type != BPF_MAP_TYPE_INODE_STORAGE &&
> -		    map->map_type != BPF_MAP_TYPE_TASK_STORAGE)
> +		    map->map_type != BPF_MAP_TYPE_TASK_STORAGE &&
> +		    map->map_type != BPF_MAP_TYPE_CGROUP_LOCAL_STORAGE)
>   			return -ENOTSUPP;
>   		if (map->spin_lock_off + sizeof(struct bpf_spin_lock) >
>   		    map->value_size) {
> diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
> index 6f6d2d511c06..f36f6a3c0d50 100644
> --- a/kernel/bpf/verifier.c
> +++ b/kernel/bpf/verifier.c
> @@ -6360,6 +6360,11 @@ static int check_map_func_compatibility(struct  
> bpf_verifier_env *env,
>   		    func_id != BPF_FUNC_task_storage_delete)
>   			goto error;
>   		break;
> +	case BPF_MAP_TYPE_CGROUP_LOCAL_STORAGE:
> +		if (func_id != BPF_FUNC_cgroup_local_storage_get &&
> +		    func_id != BPF_FUNC_cgroup_local_storage_delete)
> +			goto error;
> +		break;
>   	case BPF_MAP_TYPE_BLOOM_FILTER:
>   		if (func_id != BPF_FUNC_map_peek_elem &&
>   		    func_id != BPF_FUNC_map_push_elem)
> @@ -6472,6 +6477,11 @@ static int check_map_func_compatibility(struct  
> bpf_verifier_env *env,
>   		if (map->map_type != BPF_MAP_TYPE_TASK_STORAGE)
>   			goto error;
>   		break;
> +	case BPF_FUNC_cgroup_local_storage_get:
> +	case BPF_FUNC_cgroup_local_storage_delete:
> +		if (map->map_type != BPF_MAP_TYPE_CGROUP_LOCAL_STORAGE)
> +			goto error;
> +		break;
>   	default:
>   		break;
>   	}
> @@ -12713,6 +12723,7 @@ static int check_map_prog_compatibility(struct  
> bpf_verifier_env *env,
>   		case BPF_MAP_TYPE_INODE_STORAGE:
>   		case BPF_MAP_TYPE_SK_STORAGE:
>   		case BPF_MAP_TYPE_TASK_STORAGE:
> +		case BPF_MAP_TYPE_CGROUP_LOCAL_STORAGE:
>   			break;
>   		default:
>   			verbose(env,
> @@ -14149,7 +14160,8 @@ static int do_misc_fixups(struct bpf_verifier_env  
> *env)

>   		if (insn->imm == BPF_FUNC_task_storage_get ||
>   		    insn->imm == BPF_FUNC_sk_storage_get ||
> -		    insn->imm == BPF_FUNC_inode_storage_get) {
> +		    insn->imm == BPF_FUNC_inode_storage_get ||
> +		    insn->imm == BPF_FUNC_cgroup_local_storage_get) {
>   			if (env->prog->aux->sleepable)
>   				insn_buf[0] = BPF_MOV64_IMM(BPF_REG_5, (__force __s32)GFP_KERNEL);
>   			else
> diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
> index 8ad2c267ff47..2fa2c950c7fb 100644
> --- a/kernel/cgroup/cgroup.c
> +++ b/kernel/cgroup/cgroup.c
> @@ -985,6 +985,10 @@ void put_css_set_locked(struct css_set *cset)
>   		put_css_set_locked(cset->dom_cset);
>   	}

> +#ifdef CONFIG_BPF_SYSCALL
> +	bpf_local_cgroup_storage_free(cset->dfl_cgrp);
> +#endif
> +
>   	kfree_rcu(cset, rcu_head);
>   }

> diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
> index 688552df95ca..179adaae4a9f 100644
> --- a/kernel/trace/bpf_trace.c
> +++ b/kernel/trace/bpf_trace.c
> @@ -1454,6 +1454,10 @@ bpf_tracing_func_proto(enum bpf_func_id func_id,  
> const struct bpf_prog *prog)
>   		return &bpf_get_current_cgroup_id_proto;
>   	case BPF_FUNC_get_current_ancestor_cgroup_id:
>   		return &bpf_get_current_ancestor_cgroup_id_proto;
> +	case BPF_FUNC_cgroup_local_storage_get:
> +		return &bpf_cgroup_storage_get_proto;
> +	case BPF_FUNC_cgroup_local_storage_delete:
> +		return &bpf_cgroup_storage_delete_proto;
>   #endif
>   	case BPF_FUNC_send_signal:
>   		return &bpf_send_signal_proto;
> diff --git a/scripts/bpf_doc.py b/scripts/bpf_doc.py
> index c0e6690be82a..fdb0aff8cb5a 100755
> --- a/scripts/bpf_doc.py
> +++ b/scripts/bpf_doc.py
> @@ -685,6 +685,7 @@ class PrinterHelpers(Printer):
>               'struct udp6_sock',
>               'struct unix_sock',
>               'struct task_struct',
> +            'struct cgroup',

>               'struct __sk_buff',
>               'struct sk_msg_md',
> @@ -742,6 +743,7 @@ class PrinterHelpers(Printer):
>               'struct udp6_sock',
>               'struct unix_sock',
>               'struct task_struct',
> +            'struct cgroup',
>               'struct path',
>               'struct btf_ptr',
>               'struct inode',
> diff --git a/tools/include/uapi/linux/bpf.h  
> b/tools/include/uapi/linux/bpf.h
> index 17f61338f8f8..d918b4054297 100644
> --- a/tools/include/uapi/linux/bpf.h
> +++ b/tools/include/uapi/linux/bpf.h
> @@ -935,6 +935,7 @@ enum bpf_map_type {
>   	BPF_MAP_TYPE_TASK_STORAGE,
>   	BPF_MAP_TYPE_BLOOM_FILTER,
>   	BPF_MAP_TYPE_USER_RINGBUF,
> +	BPF_MAP_TYPE_CGROUP_LOCAL_STORAGE,
>   };

>   /* Note that tracing related programs such as
> @@ -5435,6 +5436,42 @@ union bpf_attr {
>    *		**-E2BIG** if user-space has tried to publish a sample which is
>    *		larger than the size of the ring buffer, or which cannot fit
>    *		within a struct bpf_dynptr.
> + *
> + * void *bpf_cgroup_local_storage_get(struct bpf_map *map, struct cgroup  
> *cgroup, void *value, u64 flags)
> + *	Description
> + *		Get a bpf_local_storage from the *cgroup*.
> + *
> + *		Logically, it could be thought of as getting the value from
> + *		a *map* with *cgroup* as the **key**.  From this
> + *		perspective,  the usage is not much different from
> + *		**bpf_map_lookup_elem**\ (*map*, **&**\ *cgroup*) except this
> + *		helper enforces the key must be a cgroup struct and the map must also
> + *		be a **BPF_MAP_TYPE_CGROUP_LOCAL_STORAGE**.
> + *
> + *		Underneath, the value is stored locally at *cgroup* instead of
> + *		the *map*.  The *map* is used as the bpf-local-storage
> + *		"type". The bpf-local-storage "type" (i.e. the *map*) is
> + *		searched against all bpf_local_storage residing at *cgroup*.
> + *
> + *		An optional *flags* (**BPF_LOCAL_STORAGE_GET_F_CREATE**) can be
> + *		used such that a new bpf_local_storage will be
> + *		created if one does not exist.  *value* can be used
> + *		together with **BPF_LOCAL_STORAGE_GET_F_CREATE** to specify
> + *		the initial value of a bpf_local_storage.  If *value* is
> + *		**NULL**, the new bpf_local_storage will be zero initialized.
> + *	Return
> + *		A bpf_local_storage pointer is returned on success.
> + *
> + *		**NULL** if not found or there was an error in adding
> + *		a new bpf_local_storage.
> + *
> + * long bpf_cgroup_local_storage_delete(struct bpf_map *map, struct  
> cgroup *cgroup)
> + *	Description
> + *		Delete a bpf_local_storage from a *cgroup*.
> + *	Return
> + *		0 on success.
> + *
> + *		**-ENOENT** if the bpf_local_storage cannot be found.
>    */
>   #define ___BPF_FUNC_MAPPER(FN, ctx...)			\
>   	FN(unspec, 0, ##ctx)				\
> @@ -5647,6 +5684,8 @@ union bpf_attr {
>   	FN(tcp_raw_check_syncookie_ipv6, 207, ##ctx)	\
>   	FN(ktime_get_tai_ns, 208, ##ctx)		\
>   	FN(user_ringbuf_drain, 209, ##ctx)		\
> +	FN(cgroup_local_storage_get, 210, ##ctx)	\
> +	FN(cgroup_local_storage_delete, 211, ##ctx)	\
>   	/* */

>   /* backwards-compatibility macros for users of __BPF_FUNC_MAPPER that  
> don't
> --
> 2.30.2