Commit d7bf2c10 authored by Roman Gushchin's avatar Roman Gushchin Committed by Daniel Borkmann
Browse files

bpf: allocate cgroup storage entries on attaching bpf programs 



If a bpf program is using cgroup local storage, allocate
a bpf_cgroup_storage structure automatically on attaching the program
to a cgroup and save the pointer into the corresponding bpf_prog_list
entry.
Analogically, release the cgroup local storage on detaching
of the bpf program.

Signed-off-by: default avatarRoman Gushchin <guro@fb.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: default avatarMartin KaFai Lau <kafai@fb.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
parent aa0ad5b0

include/linux/bpf-cgroup.h

+1 −0
Original line number Diff line number Diff line
@@ -43,6 +43,7 @@ struct bpf_cgroup_storage { 
struct bpf_prog_list {

	struct list_head node;

	struct bpf_prog *prog;

	struct bpf_cgroup_storage *storage;

};



struct bpf_prog_array;

kernel/bpf/cgroup.c

+31 −4
Original line number Diff line number Diff line
@@ -34,6 +34,8 @@ void cgroup_bpf_put(struct cgroup *cgrp) 
		list_for_each_entry_safe(pl, tmp, progs, node) {

			list_del(&pl->node);

			bpf_prog_put(pl->prog);

			bpf_cgroup_storage_unlink(pl->storage);

			bpf_cgroup_storage_free(pl->storage);

			kfree(pl);

			static_branch_dec(&cgroup_bpf_enabled_key);

		}
@@ -188,6 +190,7 @@ int __cgroup_bpf_attach(struct cgroup *cgrp, struct bpf_prog *prog, 
{

	struct list_head *progs = &cgrp->bpf.progs[type];

	struct bpf_prog *old_prog = NULL;

	struct bpf_cgroup_storage *storage, *old_storage = NULL;

	struct cgroup_subsys_state *css;

	struct bpf_prog_list *pl;

	bool pl_was_allocated;
@@ -210,31 +213,47 @@ int __cgroup_bpf_attach(struct cgroup *cgrp, struct bpf_prog *prog, 
	if (prog_list_length(progs) >= BPF_CGROUP_MAX_PROGS)

		return -E2BIG;



	storage = bpf_cgroup_storage_alloc(prog);

	if (IS_ERR(storage))

		return -ENOMEM;



	if (flags & BPF_F_ALLOW_MULTI) {

		list_for_each_entry(pl, progs, node)

			if (pl->prog == prog)

		list_for_each_entry(pl, progs, node) {

			if (pl->prog == prog) {

				/* disallow attaching the same prog twice */

				bpf_cgroup_storage_free(storage);

				return -EINVAL;

			}

		}



		pl = kmalloc(sizeof(*pl), GFP_KERNEL);

		if (!pl)

		if (!pl) {

			bpf_cgroup_storage_free(storage);

			return -ENOMEM;

		}



		pl_was_allocated = true;

		pl->prog = prog;

		pl->storage = storage;

		list_add_tail(&pl->node, progs);

	} else {

		if (list_empty(progs)) {

			pl = kmalloc(sizeof(*pl), GFP_KERNEL);

			if (!pl)

			if (!pl) {

				bpf_cgroup_storage_free(storage);

				return -ENOMEM;

			}

			pl_was_allocated = true;

			list_add_tail(&pl->node, progs);

		} else {

			pl = list_first_entry(progs, typeof(*pl), node);

			old_prog = pl->prog;

			old_storage = pl->storage;

			bpf_cgroup_storage_unlink(old_storage);

			pl_was_allocated = false;

		}

		pl->prog = prog;

		pl->storage = storage;

	}



	cgrp->bpf.flags[type] = flags;
@@ -257,10 +276,13 @@ int __cgroup_bpf_attach(struct cgroup *cgrp, struct bpf_prog *prog, 
	}



	static_branch_inc(&cgroup_bpf_enabled_key);

	if (old_storage)

		bpf_cgroup_storage_free(old_storage);

	if (old_prog) {

		bpf_prog_put(old_prog);

		static_branch_dec(&cgroup_bpf_enabled_key);

	}

	bpf_cgroup_storage_link(storage, cgrp, type);

	return 0;



cleanup:
@@ -276,6 +298,9 @@ cleanup: 


	/* and cleanup the prog list */

	pl->prog = old_prog;

	bpf_cgroup_storage_free(pl->storage);

	pl->storage = old_storage;

	bpf_cgroup_storage_link(old_storage, cgrp, type);

	if (pl_was_allocated) {

		list_del(&pl->node);

		kfree(pl);
@@ -356,6 +381,8 @@ int __cgroup_bpf_detach(struct cgroup *cgrp, struct bpf_prog *prog, 


	/* now can actually delete it from this cgroup list */

	list_del(&pl->node);

	bpf_cgroup_storage_unlink(pl->storage);

	bpf_cgroup_storage_free(pl->storage);

	kfree(pl);

	if (list_empty(progs))

		/* last program was detached, reset flags to zero */

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