Commit ae24345d authored by Yonghong Song's avatar Yonghong Song Committed by Alexei Starovoitov
Browse files

bpf: Implement an interface to register bpf_iter targets 



The target can call bpf_iter_reg_target() to register itself.
The needed information:
  target:           target name
  seq_ops:          the seq_file operations for the target
  init_seq_private  target callback to initialize seq_priv during file open
  fini_seq_private  target callback to clean up seq_priv during file release
  seq_priv_size:    the private_data size needed by the seq_file
                    operations

The target name represents a target which provides a seq_ops
for iterating objects.

The target can provide two callback functions, init_seq_private
and fini_seq_private, called during file open/release time.
For example, /proc/net/{tcp6, ipv6_route, netlink, ...}, net
name space needs to be setup properly during file open and
released properly during file release.

Function bpf_iter_unreg_target() is also implemented to unregister
a particular target.

Signed-off-by: default avatarYonghong Song <yhs@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Acked-by: default avatarAndrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200509175859.2474669-1-yhs@fb.com
parent 8086fbaf

include/linux/bpf.h

+15 −0
Original line number Diff line number Diff line
@@ -31,6 +31,7 @@ struct seq_file; 
struct btf;

struct btf_type;

struct exception_table_entry;

struct seq_operations;



extern struct idr btf_idr;

extern spinlock_t btf_idr_lock;
@@ -1126,6 +1127,20 @@ struct bpf_link *bpf_link_get_from_fd(u32 ufd); 
int bpf_obj_pin_user(u32 ufd, const char __user *pathname);

int bpf_obj_get_user(const char __user *pathname, int flags);



typedef int (*bpf_iter_init_seq_priv_t)(void *private_data);

typedef void (*bpf_iter_fini_seq_priv_t)(void *private_data);



struct bpf_iter_reg {

	const char *target;

	const struct seq_operations *seq_ops;

	bpf_iter_init_seq_priv_t init_seq_private;

	bpf_iter_fini_seq_priv_t fini_seq_private;

	u32 seq_priv_size;

};



int bpf_iter_reg_target(struct bpf_iter_reg *reg_info);

void bpf_iter_unreg_target(const char *target);



int bpf_percpu_hash_copy(struct bpf_map *map, void *key, void *value);

int bpf_percpu_array_copy(struct bpf_map *map, void *key, void *value);

int bpf_percpu_hash_update(struct bpf_map *map, void *key, void *value,

kernel/bpf/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -2,7 +2,7 @@ 
obj-y := core.o

CFLAGS_core.o += $(call cc-disable-warning, override-init)



obj-$(CONFIG_BPF_SYSCALL) += syscall.o verifier.o inode.o helpers.o tnum.o

obj-$(CONFIG_BPF_SYSCALL) += syscall.o verifier.o inode.o helpers.o tnum.o bpf_iter.o

obj-$(CONFIG_BPF_SYSCALL) += hashtab.o arraymap.o percpu_freelist.o bpf_lru_list.o lpm_trie.o map_in_map.o

obj-$(CONFIG_BPF_SYSCALL) += local_storage.o queue_stack_maps.o

obj-$(CONFIG_BPF_SYSCALL) += disasm.o

kernel/bpf/bpf_iter.c

0 → 100644
+59 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0-only

/* Copyright (c) 2020 Facebook */



#include <linux/fs.h>

#include <linux/filter.h>

#include <linux/bpf.h>



struct bpf_iter_target_info {

	struct list_head list;

	const char *target;

	const struct seq_operations *seq_ops;

	bpf_iter_init_seq_priv_t init_seq_private;

	bpf_iter_fini_seq_priv_t fini_seq_private;

	u32 seq_priv_size;

};



static struct list_head targets = LIST_HEAD_INIT(targets);

static DEFINE_MUTEX(targets_mutex);



int bpf_iter_reg_target(struct bpf_iter_reg *reg_info)

{

	struct bpf_iter_target_info *tinfo;



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

	if (!tinfo)

		return -ENOMEM;



	tinfo->target = reg_info->target;

	tinfo->seq_ops = reg_info->seq_ops;

	tinfo->init_seq_private = reg_info->init_seq_private;

	tinfo->fini_seq_private = reg_info->fini_seq_private;

	tinfo->seq_priv_size = reg_info->seq_priv_size;

	INIT_LIST_HEAD(&tinfo->list);



	mutex_lock(&targets_mutex);

	list_add(&tinfo->list, &targets);

	mutex_unlock(&targets_mutex);



	return 0;

}



void bpf_iter_unreg_target(const char *target)

{

	struct bpf_iter_target_info *tinfo;

	bool found = false;



	mutex_lock(&targets_mutex);

	list_for_each_entry(tinfo, &targets, list) {

		if (!strcmp(target, tinfo->target)) {

			list_del(&tinfo->list);

			kfree(tinfo);

			found = true;

			break;

		}

	}

	mutex_unlock(&targets_mutex);



	WARN_ON(found == false);

}

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