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.

Yonghong Song committed 6 years ago

Commit ae243451 parent 8086fba3 files · +75 −1Browse files

Unified · Split

3 files

include/linux/bpf.h +15 −0
kernel/bpf/Makefile +1 −1
kernel/bpf/bpf_iter.c +59 −0

include/linux/bpf.h+15−0

@@ -31,6 +31,7 @@ struct seq_file; · 30 unmodified lines
31	31	struct btf;
32	32	struct btf_type;
33	33	struct exception_table_entry;
	34	+struct seq_operations;
34	35
35	36	extern struct idr btf_idr;
36	37	extern spinlock_t btf_idr_lock;
@@ -1126,6 +1127,20 @@ struct bpf_link *bpf_link_get_from_fd(u32 ufd); · 1089 unmodified lines
1126	1127	int bpf_obj_pin_user(u32 ufd, const char __user *pathname);
1127	1128	int bpf_obj_get_user(const char __user *pathname, int flags);
1128	1129
	1130	+typedef int (bpf_iter_init_seq_priv_t)(void private_data);
	1131	+typedef void (bpf_iter_fini_seq_priv_t)(void private_data);
	1132	+
	1133	+struct bpf_iter_reg {
	1134	+ const char *target;
	1135	+ const struct seq_operations *seq_ops;
	1136	+ bpf_iter_init_seq_priv_t init_seq_private;
	1137	+ bpf_iter_fini_seq_priv_t fini_seq_private;
	1138	+ u32 seq_priv_size;
	1139	+};
	1140	+
	1141	+int bpf_iter_reg_target(struct bpf_iter_reg *reg_info);
	1142	+void bpf_iter_unreg_target(const char *target);
	1143	+
1129	1144	int bpf_percpu_hash_copy(struct bpf_map map, void key, void *value);
1130	1145	int bpf_percpu_array_copy(struct bpf_map map, void key, void *value);
1131	1146	int bpf_percpu_hash_update(struct bpf_map map, void key, void *value,

kernel/bpf/Makefile+1−1

@@ -2,7 +2,7 @@ · 1 unmodified line
2	2	obj-y := core.o
3	3	CFLAGS_core.o += $(call cc-disable-warning, override-init)
4	4
5		−obj-$(CONFIG_BPF_SYSCALL) += syscall.o verifier.o inode.o helpers.o tnum.o
	5	+obj-$(CONFIG_BPF_SYSCALL) += syscall.o verifier.o inode.o helpers.o tnum.o bpf_iter.o
6	6	obj-$(CONFIG_BPF_SYSCALL) += hashtab.o arraymap.o percpu_freelist.o bpf_lru_list.o lpm_trie.o map_in_map.o
7	7	obj-$(CONFIG_BPF_SYSCALL) += local_storage.o queue_stack_maps.o
8	8	obj-$(CONFIG_BPF_SYSCALL) += disasm.o

kernel/bpf/bpf_iter.c+59−0

@@ -0,0 +1,59 @@
	1	+// SPDX-License-Identifier: GPL-2.0-only
	2	+/* Copyright (c) 2020 Facebook */
	3	+
	4	+#include <linux/fs.h>
	5	+#include <linux/filter.h>
	6	+#include <linux/bpf.h>
	7	+
	8	+struct bpf_iter_target_info {
	9	+ struct list_head list;
	10	+ const char *target;
	11	+ const struct seq_operations *seq_ops;
	12	+ bpf_iter_init_seq_priv_t init_seq_private;
	13	+ bpf_iter_fini_seq_priv_t fini_seq_private;
	14	+ u32 seq_priv_size;
	15	+};
	16	+
	17	+static struct list_head targets = LIST_HEAD_INIT(targets);
	18	+static DEFINE_MUTEX(targets_mutex);
	19	+
	20	+int bpf_iter_reg_target(struct bpf_iter_reg *reg_info)
	21	+{
	22	+ struct bpf_iter_target_info *tinfo;
	23	+
	24	+ tinfo = kmalloc(sizeof(*tinfo), GFP_KERNEL);
	25	+ if (!tinfo)
	26	+ return -ENOMEM;
	27	+
	28	+ tinfo->target = reg_info->target;
	29	+ tinfo->seq_ops = reg_info->seq_ops;
	30	+ tinfo->init_seq_private = reg_info->init_seq_private;
	31	+ tinfo->fini_seq_private = reg_info->fini_seq_private;
	32	+ tinfo->seq_priv_size = reg_info->seq_priv_size;
	33	+ INIT_LIST_HEAD(&tinfo->list);
	34	+
	35	+ mutex_lock(&targets_mutex);
	36	+ list_add(&tinfo->list, &targets);
	37	+ mutex_unlock(&targets_mutex);
	38	+
	39	+ return 0;
	40	+}
	41	+
	42	+void bpf_iter_unreg_target(const char *target)
	43	+{
	44	+ struct bpf_iter_target_info *tinfo;
	45	+ bool found = false;
	46	+
	47	+ mutex_lock(&targets_mutex);
	48	+ list_for_each_entry(tinfo, &targets, list) {
	49	+ if (!strcmp(target, tinfo->target)) {
	50	+ list_del(&tinfo->list);
	51	+ kfree(tinfo);
	52	+ found = true;
	53	+ break;
	54	+ }
	55	+ }
	56	+ mutex_unlock(&targets_mutex);
	57	+
	58	+ WARN_ON(found == false);
	59	+}