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bpf: extend cgroup bpf core to allow multiple cgroup storage types
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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 <guro@fb.com>
Acked-by: Song Liu <songliubraving@fb.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
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Roman Gushchin authored and Daniel Borkmann committed Oct 1, 2018
1 parent 5bf7a60 commit 8bad74f
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Showing 8 changed files with 136 additions and 57 deletions.
38 changes: 28 additions & 10 deletions include/linux/bpf-cgroup.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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>
Expand All @@ -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;

Expand All @@ -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;
Expand Down Expand Up @@ -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,
Expand Down Expand Up @@ -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) {}

Expand All @@ -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 */
11 changes: 9 additions & 2 deletions include/linux/bpf.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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;
Expand All @@ -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;
Expand Down Expand Up @@ -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 {
Expand Down
74 changes: 52 additions & 22 deletions kernel/bpf/cgroup.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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++) {
Expand All @@ -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);
}
Expand Down Expand Up @@ -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;
Expand Down Expand Up @@ -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)));
Expand Down Expand Up @@ -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;
Expand All @@ -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;
Expand All @@ -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);
Expand All @@ -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;
Expand Down Expand Up @@ -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 */
Expand Down
15 changes: 9 additions & 6 deletions kernel/bpf/helpers.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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 = {
Expand All @@ -214,3 +216,4 @@ const struct bpf_func_proto bpf_get_local_storage_proto = {
.arg2_type = ARG_ANYTHING,
};
#endif
#endif
18 changes: 11 additions & 7 deletions kernel/bpf/local_storage.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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

Expand Down Expand Up @@ -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);
Expand All @@ -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;

Expand Down
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