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

Stanislav Fomichev
2022-10-17T21:04:12Z

On Mon, Oct 17, 2022 at 12:25 PM Yonghong Song <yhs@meta.com> wrote:
>
>
>
> On 10/17/22 11:01 AM, sdf@google.com wrote:
> > 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?
>
> Thinking differently. I think I would have reuse the same map name
> (BPF_MAP_TYPE_CGROUP_STORAGE) but with a flag like
> BPF_F_LOCAL_STORAGE_GENERIC).
>
> We could use map_extra as well, but I think an explicit flag might be
> better.

Ack, flag and map_extra might work as well. They are more explicit,
which is good/bad depending on who you talk to.
I was assuming that we can just support the following:

struct {
__uint(type, BPF_MAP_TYPE_CGROUP_STORAGE);
__type(key, int);
__type(value, xxx);
} ...;

and depend on key_size == sizeof(int), but up to you; just trying to
understand whether it makes sense to share the name or not.

Sharing the helper probably not worth it given the special treatment?
Or maybe it can be a shortcut to "lookup this map with my cgroup"?

> >
> > 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
> >