Re: [PATCH bpf-next v2 2/6] bpf: Implement cgroup storage available to non-cgroup-attached bpf progs

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On Thu, Oct 20, 2022 at 3:13 PM Yonghong Song <yhs@xxxxxx> 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_cgrp_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.
>
> Typically, the following code is used to get the current cgroup:
>     struct task_struct *task = bpf_get_current_task_btf();
>     ... task->cgroups->dfl_cgrp ...
> and in structure task_struct definition:
>     struct task_struct {
>         ....
>         struct css_set __rcu            *cgroups;
>         ....
>     }
> With sleepable program, accessing task->cgroups is not protected by rcu_read_lock.
> So the current implementation only supports non-sleepable program and supporting
> sleepable program will be the next step together with adding rcu_read_lock
> protection for rcu tagged structures.
>
> Since map name BPF_MAP_TYPE_CGROUP_STORAGE has been used for old cgroup local
> storage support, the new map name BPF_MAP_TYPE_CGRP_STORAGE is used
> for cgroup storage available to non-cgroup-attached bpf programs. The old
> cgroup storage supports bpf_get_local_storage() helper to get the cgroup data.
> The new cgroup storage helper bpf_cgrp_storage_get() can provide similar
> functionality. While old cgroup storage pre-allocates storage memory, the new
> mechanism can also pre-allocate with a user space bpf_map_update_elem() call
> to avoid potential run-time memory allocaiton failure.
> Therefore, the new cgroup storage can provide all functionality w.r.t.
> the old one. So in uapi bpf.h, the old BPF_MAP_TYPE_CGROUP_STORAGE is alias to
> BPF_MAP_TYPE_CGROUP_STORAGE_DEPRECATED to indicate the old cgroup storage can
> be deprecated since the new one can provide the same functionality.
>
> Signed-off-by: Yonghong Song <yhs@xxxxxx>
> ---
>  include/linux/bpf.h            |   3 +
>  include/linux/bpf_types.h      |   1 +
>  include/linux/cgroup-defs.h    |   4 +
>  include/uapi/linux/bpf.h       |  48 +++++-
>  kernel/bpf/Makefile            |   2 +-
>  kernel/bpf/bpf_cgrp_storage.c  | 276 +++++++++++++++++++++++++++++++++
>  kernel/bpf/helpers.c           |   6 +
>  kernel/bpf/syscall.c           |   3 +-
>  kernel/bpf/verifier.c          |  13 +-
>  kernel/cgroup/cgroup.c         |   4 +
>  kernel/trace/bpf_trace.c       |   4 +
>  scripts/bpf_doc.py             |   2 +
>  tools/include/uapi/linux/bpf.h |  48 +++++-
>  13 files changed, 409 insertions(+), 5 deletions(-)
>  create mode 100644 kernel/bpf/bpf_cgrp_storage.c
>
> diff --git a/include/linux/bpf.h b/include/linux/bpf.h
> index 9e7d46d16032..674da3129248 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_cgrp_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_cgrp_storage_get_proto;
> +extern const struct bpf_func_proto bpf_cgrp_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..f9d5aa62fed0 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_CGRP_STORAGE, cgrp_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 8f481d1b159a..4a72bc3a0a4e 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_CGROUP_BPF
> +       struct bpf_local_storage __rcu  *bpf_cgrp_storage;
> +#endif

Why is this protected by CONFIG_CGROUP_BPF as opposed to
CONFIG_CGROUPS && CONFIG_BPF_SYSCALL?

It seems to me (and you also point this out in a different reply) that
CONFIG_CGROUP_BPF is mostly used for bpf programs that attach to
cgroups, right?

(same for the freeing site)

> +
>         /* All ancestors including self */
>         struct cgroup *ancestors[];
>  };
> diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> index 17f61338f8f8..2d7f79bf3500 100644
> --- a/include/uapi/linux/bpf.h
> +++ b/include/uapi/linux/bpf.h
> @@ -922,7 +922,14 @@ enum bpf_map_type {
>         BPF_MAP_TYPE_CPUMAP,
>         BPF_MAP_TYPE_XSKMAP,
>         BPF_MAP_TYPE_SOCKHASH,
> -       BPF_MAP_TYPE_CGROUP_STORAGE,
> +       BPF_MAP_TYPE_CGROUP_STORAGE_DEPRECATED,
> +       /* BPF_MAP_TYPE_CGROUP_STORAGE is available to bpf programs attaching
> +        * to a cgroup. The newer BPF_MAP_TYPE_CGRP_STORAGE is available to
> +        * both cgroup-attached and other progs and supports all functionality
> +        * provided by BPF_MAP_TYPE_CGROUP_STORAGE. So mark
> +        * BPF_MAP_TYPE_CGROUP_STORAGE deprecated.
> +        */
> +       BPF_MAP_TYPE_CGROUP_STORAGE = BPF_MAP_TYPE_CGROUP_STORAGE_DEPRECATED,
>         BPF_MAP_TYPE_REUSEPORT_SOCKARRAY,
>         BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE,
>         BPF_MAP_TYPE_QUEUE,
> @@ -935,6 +942,7 @@ enum bpf_map_type {
>         BPF_MAP_TYPE_TASK_STORAGE,
>         BPF_MAP_TYPE_BLOOM_FILTER,
>         BPF_MAP_TYPE_USER_RINGBUF,
> +       BPF_MAP_TYPE_CGRP_STORAGE,
>  };
>
>  /* Note that tracing related programs such as
> @@ -5435,6 +5443,42 @@ 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_cgrp_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_CGRP_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_cgrp_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 +5691,8 @@ 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(cgrp_storage_get, 210, ##ctx)                \
> +       FN(cgrp_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..3a12e6b400a2 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-$(CONFIG_BPF_SYSCALL) += cgroup_iter.o bpf_cgrp_storage.o
>  endif
>  obj-$(CONFIG_CGROUP_BPF) += cgroup.o
>  ifeq ($(CONFIG_INET),y)
> diff --git a/kernel/bpf/bpf_cgrp_storage.c b/kernel/bpf/bpf_cgrp_storage.c
> new file mode 100644
> index 000000000000..bcc5f0fc20be
> --- /dev/null
> +++ b/kernel/bpf/bpf_cgrp_storage.c
> @@ -0,0 +1,276 @@
> +// 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_cgrp_storage_busy);
> +
> +static void bpf_cgrp_storage_lock(void)
> +{
> +       migrate_disable();
> +       this_cpu_inc(bpf_cgrp_storage_busy);
> +}
> +
> +static void bpf_cgrp_storage_unlock(void)
> +{
> +       this_cpu_dec(bpf_cgrp_storage_busy);
> +       migrate_enable();
> +}
> +
> +static bool bpf_cgrp_storage_trylock(void)
> +{
> +       migrate_disable();
> +       if (unlikely(this_cpu_inc_return(bpf_cgrp_storage_busy) != 1)) {
> +               this_cpu_dec(bpf_cgrp_storage_busy);
> +               migrate_enable();
> +               return false;
> +       }
> +       return true;
> +}
> +
> +static struct bpf_local_storage __rcu **cgroup_storage_ptr(void *owner)
> +{
> +       struct cgroup *cg = owner;
> +
> +       return &cg->bpf_cgrp_storage;
> +}
> +
> +void bpf_cgrp_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_cgrp_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_cgrp_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_cgrp_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_cgrp_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_cgrp_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_cgrp_storage_lock();
> +       sdata = cgroup_storage_lookup(cgroup, map, true);
> +       bpf_cgrp_storage_unlock();
> +       cgroup_put(cgroup);
> +       return sdata ? sdata->data : NULL;
> +}
> +
> +static int bpf_cgrp_storage_update_elem(struct bpf_map *map, void *key,
> +                                         void *value, u64 map_flags)
> +{
> +       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 PTR_ERR(cgroup);
> +
> +       bpf_cgrp_storage_lock();
> +       sdata = bpf_local_storage_update(cgroup, (struct bpf_local_storage_map *)map,
> +                                        value, map_flags, GFP_ATOMIC);
> +       bpf_cgrp_storage_unlock();
> +       cgroup_put(cgroup);
> +       return PTR_ERR_OR_ZERO(sdata);
> +}
> +
> +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_cgrp_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_cgrp_storage_lock();
> +       err = cgroup_storage_delete(cgroup, map);
> +       bpf_cgrp_storage_unlock();
> +       cgroup_put(cgroup);
> +       return err;
> +}
> +
> +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_cgrp_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_cgrp_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_cgrp_storage_unlock();
> +       return IS_ERR_OR_NULL(sdata) ? (unsigned long)NULL : (unsigned long)sdata->data;
> +}
> +
> +BPF_CALL_2(bpf_cgrp_storage_delete, struct bpf_map *, map, struct cgroup *, cgroup)
> +{
> +       int ret;
> +
> +       WARN_ON_ONCE(!bpf_rcu_lock_held());
> +       if (!cgroup)
> +               return -EINVAL;
> +
> +       if (!bpf_cgrp_storage_trylock())
> +               return -EBUSY;
> +
> +       ret = cgroup_storage_delete(cgroup, map);
> +       bpf_cgrp_storage_unlock();
> +       return ret;
> +}
> +
> +BTF_ID_LIST_SINGLE(cgroup_storage_map_btf_ids, struct, bpf_local_storage_map)
> +const struct bpf_map_ops cgrp_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_cgrp_storage_lookup_elem,
> +       .map_update_elem = bpf_cgrp_storage_update_elem,
> +       .map_delete_elem = bpf_cgrp_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_cgrp_storage_get_proto = {
> +       .func           = bpf_cgrp_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_cgrp_storage_delete_proto = {
> +       .func           = bpf_cgrp_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..124fd199ce5c 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_cgrp_storage_get:
> +               return &bpf_cgrp_storage_get_proto;
> +       case BPF_FUNC_cgrp_storage_delete:
> +               return &bpf_cgrp_storage_delete_proto;
> +#endif
>         default:
>                 break;
>         }
> diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
> index 7b373a5e861f..b95c276f92e3 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_CGRP_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..82bb18d7e881 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_CGRP_STORAGE:
> +               if (func_id != BPF_FUNC_cgrp_storage_get &&
> +                   func_id != BPF_FUNC_cgrp_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_cgrp_storage_get:
> +       case BPF_FUNC_cgrp_storage_delete:
> +               if (map->map_type != BPF_MAP_TYPE_CGRP_STORAGE)
> +                       goto error;
> +               break;
>         default:
>                 break;
>         }
> @@ -14149,7 +14159,8 @@ 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_cgrp_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 764bdd5fd8d1..7e80e15fae4e 100644
> --- a/kernel/cgroup/cgroup.c
> +++ b/kernel/cgroup/cgroup.c
> @@ -5227,6 +5227,10 @@ static void css_free_rwork_fn(struct work_struct *work)
>         struct cgroup_subsys *ss = css->ss;
>         struct cgroup *cgrp = css->cgroup;
>
> +#ifdef CONFIG_CGROUP_BPF
> +       bpf_cgrp_storage_free(cgrp);
> +#endif
> +
>         percpu_ref_exit(&css->refcnt);
>
>         if (ss) {
> diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
> index 49fb9ec8366d..0ddf0834b1b8 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_cgrp_storage_get:
> +               return &bpf_cgrp_storage_get_proto;
> +       case BPF_FUNC_cgrp_storage_delete:
> +               return &bpf_cgrp_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..2d7f79bf3500 100644
> --- a/tools/include/uapi/linux/bpf.h
> +++ b/tools/include/uapi/linux/bpf.h
> @@ -922,7 +922,14 @@ enum bpf_map_type {
>         BPF_MAP_TYPE_CPUMAP,
>         BPF_MAP_TYPE_XSKMAP,
>         BPF_MAP_TYPE_SOCKHASH,
> -       BPF_MAP_TYPE_CGROUP_STORAGE,
> +       BPF_MAP_TYPE_CGROUP_STORAGE_DEPRECATED,
> +       /* BPF_MAP_TYPE_CGROUP_STORAGE is available to bpf programs attaching
> +        * to a cgroup. The newer BPF_MAP_TYPE_CGRP_STORAGE is available to
> +        * both cgroup-attached and other progs and supports all functionality
> +        * provided by BPF_MAP_TYPE_CGROUP_STORAGE. So mark
> +        * BPF_MAP_TYPE_CGROUP_STORAGE deprecated.
> +        */
> +       BPF_MAP_TYPE_CGROUP_STORAGE = BPF_MAP_TYPE_CGROUP_STORAGE_DEPRECATED,
>         BPF_MAP_TYPE_REUSEPORT_SOCKARRAY,
>         BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE,
>         BPF_MAP_TYPE_QUEUE,
> @@ -935,6 +942,7 @@ enum bpf_map_type {
>         BPF_MAP_TYPE_TASK_STORAGE,
>         BPF_MAP_TYPE_BLOOM_FILTER,
>         BPF_MAP_TYPE_USER_RINGBUF,
> +       BPF_MAP_TYPE_CGRP_STORAGE,
>  };
>
>  /* Note that tracing related programs such as
> @@ -5435,6 +5443,42 @@ 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_cgrp_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_CGRP_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_cgrp_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 +5691,8 @@ 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(cgrp_storage_get, 210, ##ctx)                \
> +       FN(cgrp_storage_delete, 211, ##ctx)             \
>         /* */
>
>  /* backwards-compatibility macros for users of __BPF_FUNC_MAPPER that don't
> --
> 2.30.2
>



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