bpf: extend cgroup bpf core to allow multiple cgroup storage types

In order to introduce per-cpu cgroup storage, let's generalize
bpf cgroup core to support multiple cgroup storage types.
Potentially, per-node cgroup storage can be added later.

This commit is mostly a formal change that replaces
cgroup_storage pointer with a array of cgroup_storage pointers.
It doesn't actually introduce a new storage type,
it will be done later.

Each bpf program is now able to have one cgroup storage of each type.

Signed-off-by: Roman Gushchin <[email protected]>
Acked-by: Song Liu <[email protected]>
Cc: Daniel Borkmann <[email protected]>
Cc: Alexei Starovoitov <[email protected]>
Signed-off-by: Daniel Borkmann <[email protected]>

include/linux/bpf-cgroup.h

@@ -2,6 +2,7 @@
 #ifndef _BPF_CGROUP_H
 #define _BPF_CGROUP_H
 
+#include <linux/bpf.h>
 #include <linux/errno.h>
 #include <linux/jump_label.h>
 #include <linux/percpu.h>
@@ -22,7 +23,10 @@ struct bpf_cgroup_storage;
 extern struct static_key_false cgroup_bpf_enabled_key;
 #define cgroup_bpf_enabled static_branch_unlikely(&cgroup_bpf_enabled_key)
 
-DECLARE_PER_CPU(void*, bpf_cgroup_storage);
+DECLARE_PER_CPU(void*, bpf_cgroup_storage[MAX_BPF_CGROUP_STORAGE_TYPE]);
+
+#define for_each_cgroup_storage_type(stype) \
+	for (stype = 0; stype < MAX_BPF_CGROUP_STORAGE_TYPE; stype++)
 
 struct bpf_cgroup_storage_map;
 
@@ -43,7 +47,7 @@ struct bpf_cgroup_storage {
 struct bpf_prog_list {
 	struct list_head node;
 	struct bpf_prog *prog;
-	struct bpf_cgroup_storage *storage;
+	struct bpf_cgroup_storage *storage[MAX_BPF_CGROUP_STORAGE_TYPE];
 };
 
 struct bpf_prog_array;
@@ -101,18 +105,29 @@ int __cgroup_bpf_run_filter_sock_ops(struct sock *sk,
 int __cgroup_bpf_check_dev_permission(short dev_type, u32 major, u32 minor,
 				      short access, enum bpf_attach_type type);
 
-static inline void bpf_cgroup_storage_set(struct bpf_cgroup_storage *storage)
+static inline enum bpf_cgroup_storage_type cgroup_storage_type(
+	struct bpf_map *map)
 {
+	return BPF_CGROUP_STORAGE_SHARED;
+}
+
+static inline void bpf_cgroup_storage_set(struct bpf_cgroup_storage
+					  *storage[MAX_BPF_CGROUP_STORAGE_TYPE])
+{
+	enum bpf_cgroup_storage_type stype;
 	struct bpf_storage_buffer *buf;
 
-	if (!storage)
-		return;
+	for_each_cgroup_storage_type(stype) {
+		if (!storage[stype])
+			continue;
 
-	buf = READ_ONCE(storage->buf);
-	this_cpu_write(bpf_cgroup_storage, &buf->data[0]);
+		buf = READ_ONCE(storage[stype]->buf);
+		this_cpu_write(bpf_cgroup_storage[stype], &buf->data[0]);
+	}
 }
 
-struct bpf_cgroup_storage *bpf_cgroup_storage_alloc(struct bpf_prog *prog);
+struct bpf_cgroup_storage *bpf_cgroup_storage_alloc(struct bpf_prog *prog,
+					enum bpf_cgroup_storage_type stype);
 void bpf_cgroup_storage_free(struct bpf_cgroup_storage *storage);
 void bpf_cgroup_storage_link(struct bpf_cgroup_storage *storage,
 			     struct cgroup *cgroup,
@@ -265,13 +280,14 @@ static inline int cgroup_bpf_prog_query(const union bpf_attr *attr,
 	return -EINVAL;
 }
 
-static inline void bpf_cgroup_storage_set(struct bpf_cgroup_storage *storage) {}
+static inline void bpf_cgroup_storage_set(
+	struct bpf_cgroup_storage *storage[MAX_BPF_CGROUP_STORAGE_TYPE]) {}
 static inline int bpf_cgroup_storage_assign(struct bpf_prog *prog,
 					    struct bpf_map *map) { return 0; }
 static inline void bpf_cgroup_storage_release(struct bpf_prog *prog,
 					      struct bpf_map *map) {}
 static inline struct bpf_cgroup_storage *bpf_cgroup_storage_alloc(
-	struct bpf_prog *prog) { return 0; }
+	struct bpf_prog *prog, enum bpf_cgroup_storage_type stype) { return 0; }
 static inline void bpf_cgroup_storage_free(
 	struct bpf_cgroup_storage *storage) {}
 
@@ -293,6 +309,8 @@ static inline void bpf_cgroup_storage_free(
 #define BPF_CGROUP_RUN_PROG_SOCK_OPS(sock_ops) ({ 0; })
 #define BPF_CGROUP_RUN_PROG_DEVICE_CGROUP(type,major,minor,access) ({ 0; })
 
+#define for_each_cgroup_storage_type(stype) for (; false; )
+
 #endif /* CONFIG_CGROUP_BPF */
 
 #endif /* _BPF_CGROUP_H */

include/linux/bpf.h

@@ -272,6 +272,13 @@ struct bpf_prog_offload {
 	u32			jited_len;
 };
 
+enum bpf_cgroup_storage_type {
+	BPF_CGROUP_STORAGE_SHARED,
+	__BPF_CGROUP_STORAGE_MAX
+};
+
+#define MAX_BPF_CGROUP_STORAGE_TYPE __BPF_CGROUP_STORAGE_MAX
+
 struct bpf_prog_aux {
 	atomic_t refcnt;
 	u32 used_map_cnt;
@@ -289,7 +296,7 @@ struct bpf_prog_aux {
 	struct bpf_prog *prog;
 	struct user_struct *user;
 	u64 load_time; /* ns since boottime */
-	struct bpf_map *cgroup_storage;
+	struct bpf_map *cgroup_storage[MAX_BPF_CGROUP_STORAGE_TYPE];
 	char name[BPF_OBJ_NAME_LEN];
 #ifdef CONFIG_SECURITY
 	void *security;
@@ -358,7 +365,7 @@ int bpf_prog_test_run_skb(struct bpf_prog *prog, const union bpf_attr *kattr,
  */
 struct bpf_prog_array_item {
 	struct bpf_prog *prog;
-	struct bpf_cgroup_storage *cgroup_storage;
+	struct bpf_cgroup_storage *cgroup_storage[MAX_BPF_CGROUP_STORAGE_TYPE];
 };
 
 struct bpf_prog_array {

kernel/bpf/cgroup.c

@@ -25,6 +25,7 @@ EXPORT_SYMBOL(cgroup_bpf_enabled_key);
  */
 void cgroup_bpf_put(struct cgroup *cgrp)
 {
+	enum bpf_cgroup_storage_type stype;
 	unsigned int type;
 
 	for (type = 0; type < ARRAY_SIZE(cgrp->bpf.progs); type++) {
@@ -34,8 +35,10 @@ 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);
+			for_each_cgroup_storage_type(stype) {
+				bpf_cgroup_storage_unlink(pl->storage[stype]);
+				bpf_cgroup_storage_free(pl->storage[stype]);
+			}
 			kfree(pl);
 			static_branch_dec(&cgroup_bpf_enabled_key);
 		}
@@ -97,6 +100,7 @@ static int compute_effective_progs(struct cgroup *cgrp,
 				   enum bpf_attach_type type,
 				   struct bpf_prog_array __rcu **array)
 {
+	enum bpf_cgroup_storage_type stype;
 	struct bpf_prog_array *progs;
 	struct bpf_prog_list *pl;
 	struct cgroup *p = cgrp;
@@ -125,7 +129,9 @@ static int compute_effective_progs(struct cgroup *cgrp,
 				continue;
 
 			progs->items[cnt].prog = pl->prog;
-			progs->items[cnt].cgroup_storage = pl->storage;
+			for_each_cgroup_storage_type(stype)
+				progs->items[cnt].cgroup_storage[stype] =
+					pl->storage[stype];
 			cnt++;
 		}
 	} while ((p = cgroup_parent(p)));
@@ -232,7 +238,9 @@ 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 bpf_cgroup_storage *storage[MAX_BPF_CGROUP_STORAGE_TYPE],
+		*old_storage[MAX_BPF_CGROUP_STORAGE_TYPE] = {NULL};
+	enum bpf_cgroup_storage_type stype;
 	struct bpf_prog_list *pl;
 	bool pl_was_allocated;
 	int err;
@@ -254,47 +262,60 @@ 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;
+	for_each_cgroup_storage_type(stype) {
+		storage[stype] = bpf_cgroup_storage_alloc(prog, stype);
+		if (IS_ERR(storage[stype])) {
+			storage[stype] = NULL;
+			for_each_cgroup_storage_type(stype)
+				bpf_cgroup_storage_free(storage[stype]);
+			return -ENOMEM;
+		}
+	}
 
 	if (flags & BPF_F_ALLOW_MULTI) {
 		list_for_each_entry(pl, progs, node) {
 			if (pl->prog == prog) {
 				/* disallow attaching the same prog twice */
-				bpf_cgroup_storage_free(storage);
+				for_each_cgroup_storage_type(stype)
+					bpf_cgroup_storage_free(storage[stype]);
 				return -EINVAL;
 			}
 		}
 
 		pl = kmalloc(sizeof(*pl), GFP_KERNEL);
 		if (!pl) {
-			bpf_cgroup_storage_free(storage);
+			for_each_cgroup_storage_type(stype)
+				bpf_cgroup_storage_free(storage[stype]);
 			return -ENOMEM;
 		}
 
 		pl_was_allocated = true;
 		pl->prog = prog;
-		pl->storage = storage;
+		for_each_cgroup_storage_type(stype)
+			pl->storage[stype] = storage[stype];
 		list_add_tail(&pl->node, progs);
 	} else {
 		if (list_empty(progs)) {
 			pl = kmalloc(sizeof(*pl), GFP_KERNEL);
 			if (!pl) {
-				bpf_cgroup_storage_free(storage);
+				for_each_cgroup_storage_type(stype)
+					bpf_cgroup_storage_free(storage[stype]);
 				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);
+			for_each_cgroup_storage_type(stype) {
+				old_storage[stype] = pl->storage[stype];
+				bpf_cgroup_storage_unlink(old_storage[stype]);
+			}
 			pl_was_allocated = false;
 		}
 		pl->prog = prog;
-		pl->storage = storage;
+		for_each_cgroup_storage_type(stype)
+			pl->storage[stype] = storage[stype];
 	}
 
 	cgrp->bpf.flags[type] = flags;
@@ -304,21 +325,27 @@ int __cgroup_bpf_attach(struct cgroup *cgrp, struct bpf_prog *prog,
 		goto cleanup;
 
 	static_branch_inc(&cgroup_bpf_enabled_key);
-	if (old_storage)
-		bpf_cgroup_storage_free(old_storage);
+	for_each_cgroup_storage_type(stype) {
+		if (!old_storage[stype])
+			continue;
+		bpf_cgroup_storage_free(old_storage[stype]);
+	}
 	if (old_prog) {
 		bpf_prog_put(old_prog);
 		static_branch_dec(&cgroup_bpf_enabled_key);
 	}
-	bpf_cgroup_storage_link(storage, cgrp, type);
+	for_each_cgroup_storage_type(stype)
+		bpf_cgroup_storage_link(storage[stype], cgrp, type);
 	return 0;
 
 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);
+	for_each_cgroup_storage_type(stype) {
+		bpf_cgroup_storage_free(pl->storage[stype]);
+		pl->storage[stype] = old_storage[stype];
+		bpf_cgroup_storage_link(old_storage[stype], cgrp, type);
+	}
 	if (pl_was_allocated) {
 		list_del(&pl->node);
 		kfree(pl);
@@ -339,6 +366,7 @@ int __cgroup_bpf_detach(struct cgroup *cgrp, struct bpf_prog *prog,
 			enum bpf_attach_type type, u32 unused_flags)
 {
 	struct list_head *progs = &cgrp->bpf.progs[type];
+	enum bpf_cgroup_storage_type stype;
 	u32 flags = cgrp->bpf.flags[type];
 	struct bpf_prog *old_prog = NULL;
 	struct bpf_prog_list *pl;
@@ -385,8 +413,10 @@ 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);
+	for_each_cgroup_storage_type(stype) {
+		bpf_cgroup_storage_unlink(pl->storage[stype]);
+		bpf_cgroup_storage_free(pl->storage[stype]);
+	}
 	kfree(pl);
 	if (list_empty(progs))
 		/* last program was detached, reset flags to zero */

kernel/bpf/helpers.c

@@ -194,16 +194,18 @@ const struct bpf_func_proto bpf_get_current_cgroup_id_proto = {
 	.ret_type	= RET_INTEGER,
 };
 
-DECLARE_PER_CPU(void*, bpf_cgroup_storage);
+#ifdef CONFIG_CGROUP_BPF
+DECLARE_PER_CPU(void*, bpf_cgroup_storage[MAX_BPF_CGROUP_STORAGE_TYPE]);
 
 BPF_CALL_2(bpf_get_local_storage, struct bpf_map *, map, u64, flags)
 {
-	/* map and flags arguments are not used now,
-	 * but provide an ability to extend the API
-	 * for other types of local storages.
-	 * verifier checks that their values are correct.
+	/* flags argument is not used now,
+	 * but provides an ability to extend the API.
+	 * verifier checks that its value is correct.
 	 */
-	return (unsigned long) this_cpu_read(bpf_cgroup_storage);
+	enum bpf_cgroup_storage_type stype = cgroup_storage_type(map);
+
+	return (unsigned long) this_cpu_read(bpf_cgroup_storage[stype]);
 }
 
 const struct bpf_func_proto bpf_get_local_storage_proto = {
@@ -214,3 +216,4 @@ const struct bpf_func_proto bpf_get_local_storage_proto = {
 	.arg2_type	= ARG_ANYTHING,
 };
 #endif
+#endif

kernel/bpf/local_storage.c

@@ -7,7 +7,7 @@
 #include <linux/rbtree.h>
 #include <linux/slab.h>
 
-DEFINE_PER_CPU(void*, bpf_cgroup_storage);
+DEFINE_PER_CPU(void*, bpf_cgroup_storage[MAX_BPF_CGROUP_STORAGE_TYPE]);
 
 #ifdef CONFIG_CGROUP_BPF
 
@@ -251,18 +251,20 @@ const struct bpf_map_ops cgroup_storage_map_ops = {
 
 int bpf_cgroup_storage_assign(struct bpf_prog *prog, struct bpf_map *_map)
 {
+	enum bpf_cgroup_storage_type stype = cgroup_storage_type(_map);
 	struct bpf_cgroup_storage_map *map = map_to_storage(_map);
 	int ret = -EBUSY;
 
 	spin_lock_bh(&map->lock);
 
 	if (map->prog && map->prog != prog)
 		goto unlock;
-	if (prog->aux->cgroup_storage && prog->aux->cgroup_storage != _map)
+	if (prog->aux->cgroup_storage[stype] &&
+	    prog->aux->cgroup_storage[stype] != _map)
 		goto unlock;
 
 	map->prog = prog;
-	prog->aux->cgroup_storage = _map;
+	prog->aux->cgroup_storage[stype] = _map;
 	ret = 0;
 unlock:
 	spin_unlock_bh(&map->lock);
@@ -272,24 +274,26 @@ int bpf_cgroup_storage_assign(struct bpf_prog *prog, struct bpf_map *_map)
 
 void bpf_cgroup_storage_release(struct bpf_prog *prog, struct bpf_map *_map)
 {
+	enum bpf_cgroup_storage_type stype = cgroup_storage_type(_map);
 	struct bpf_cgroup_storage_map *map = map_to_storage(_map);
 
 	spin_lock_bh(&map->lock);
 	if (map->prog == prog) {
-		WARN_ON(prog->aux->cgroup_storage != _map);
+		WARN_ON(prog->aux->cgroup_storage[stype] != _map);
 		map->prog = NULL;
-		prog->aux->cgroup_storage = NULL;
+		prog->aux->cgroup_storage[stype] = NULL;
 	}
 	spin_unlock_bh(&map->lock);
 }
 
-struct bpf_cgroup_storage *bpf_cgroup_storage_alloc(struct bpf_prog *prog)
+struct bpf_cgroup_storage *bpf_cgroup_storage_alloc(struct bpf_prog *prog,
+					enum bpf_cgroup_storage_type stype)
 {
 	struct bpf_cgroup_storage *storage;
 	struct bpf_map *map;
 	u32 pages;
 
-	map = prog->aux->cgroup_storage;
+	map = prog->aux->cgroup_storage[stype];
 	if (!map)
 		return NULL;