Commit f2e10bff authored by Andrii Nakryiko's avatar Andrii Nakryiko Committed by Alexei Starovoitov
Browse files

bpf: Add support for BPF_OBJ_GET_INFO_BY_FD for bpf_link 



Add ability to fetch bpf_link details through BPF_OBJ_GET_INFO_BY_FD command.
Also enhance show_fdinfo to potentially include bpf_link type-specific
information (similarly to obj_info).

Also introduce enum bpf_link_type stored in bpf_link itself and expose it in
UAPI. bpf_link_tracing also now will store and return bpf_attach_type.

Signed-off-by: default avatarAndrii Nakryiko <andriin@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200429001614.1544-5-andriin@fb.com
parent 2d602c8c

include/linux/bpf-cgroup.h

+0 −2
Original line number Diff line number Diff line
@@ -57,8 +57,6 @@ struct bpf_cgroup_link { 
	enum bpf_attach_type type;

};



extern const struct bpf_link_ops bpf_cgroup_link_lops;



struct bpf_prog_list {

	struct list_head node;

	struct bpf_prog *prog;

include/linux/bpf.h

+7 −1
Original line number Diff line number Diff line
@@ -1026,9 +1026,11 @@ extern const struct file_operations bpf_prog_fops; 
	extern const struct bpf_verifier_ops _name ## _verifier_ops;

#define BPF_MAP_TYPE(_id, _ops) \

	extern const struct bpf_map_ops _ops;

#define BPF_LINK_TYPE(_id, _name)

#include <linux/bpf_types.h>

#undef BPF_PROG_TYPE

#undef BPF_MAP_TYPE

#undef BPF_LINK_TYPE



extern const struct bpf_prog_ops bpf_offload_prog_ops;

extern const struct bpf_verifier_ops tc_cls_act_analyzer_ops;
@@ -1086,6 +1088,7 @@ int bpf_prog_new_fd(struct bpf_prog *prog); 
struct bpf_link {

	atomic64_t refcnt;

	u32 id;

	enum bpf_link_type type;

	const struct bpf_link_ops *ops;

	struct bpf_prog *prog;

	struct work_struct work;
@@ -1103,9 +1106,12 @@ struct bpf_link_ops { 
	void (*dealloc)(struct bpf_link *link);

	int (*update_prog)(struct bpf_link *link, struct bpf_prog *new_prog,

			   struct bpf_prog *old_prog);

	void (*show_fdinfo)(const struct bpf_link *link, struct seq_file *seq);

	int (*fill_link_info)(const struct bpf_link *link,

			      struct bpf_link_info *info);

};



void bpf_link_init(struct bpf_link *link,

void bpf_link_init(struct bpf_link *link, enum bpf_link_type type,

		   const struct bpf_link_ops *ops, struct bpf_prog *prog);

int bpf_link_prime(struct bpf_link *link, struct bpf_link_primer *primer);

int bpf_link_settle(struct bpf_link_primer *primer);

include/linux/bpf_types.h

+6 −0
Original line number Diff line number Diff line
@@ -118,3 +118,9 @@ BPF_MAP_TYPE(BPF_MAP_TYPE_STACK, stack_map_ops) 
#if defined(CONFIG_BPF_JIT)

BPF_MAP_TYPE(BPF_MAP_TYPE_STRUCT_OPS, bpf_struct_ops_map_ops)

#endif



BPF_LINK_TYPE(BPF_LINK_TYPE_RAW_TRACEPOINT, raw_tracepoint)

BPF_LINK_TYPE(BPF_LINK_TYPE_TRACING, tracing)

#ifdef CONFIG_CGROUP_BPF

BPF_LINK_TYPE(BPF_LINK_TYPE_CGROUP, cgroup)

#endif

include/uapi/linux/bpf.h

+28 −0
Original line number Diff line number Diff line
@@ -222,6 +222,15 @@ enum bpf_attach_type { 


#define MAX_BPF_ATTACH_TYPE __MAX_BPF_ATTACH_TYPE



enum bpf_link_type {

	BPF_LINK_TYPE_UNSPEC = 0,

	BPF_LINK_TYPE_RAW_TRACEPOINT = 1,

	BPF_LINK_TYPE_TRACING = 2,

	BPF_LINK_TYPE_CGROUP = 3,



	MAX_BPF_LINK_TYPE,

};



/* cgroup-bpf attach flags used in BPF_PROG_ATTACH command

 *

 * NONE(default): No further bpf programs allowed in the subtree.
@@ -3612,6 +3621,25 @@ struct bpf_btf_info { 
	__u32 id;

} __attribute__((aligned(8)));



struct bpf_link_info {

	__u32 type;

	__u32 id;

	__u32 prog_id;

	union {

		struct {

			__aligned_u64 tp_name; /* in/out: tp_name buffer ptr */

			__u32 tp_name_len;     /* in/out: tp_name buffer len */

		} raw_tracepoint;

		struct {

			__u32 attach_type;

		} tracing;

		struct {

			__u64 cgroup_id;

			__u32 attach_type;

		} cgroup;

	};

} __attribute__((aligned(8)));



/* User bpf_sock_addr struct to access socket fields and sockaddr struct passed

 * by user and intended to be used by socket (e.g. to bind to, depends on

 * attach attach type).

kernel/bpf/btf.c

+2 −0
Original line number Diff line number Diff line
@@ -3482,6 +3482,7 @@ extern char __weak __stop_BTF[]; 
extern struct btf *btf_vmlinux;



#define BPF_MAP_TYPE(_id, _ops)

#define BPF_LINK_TYPE(_id, _name)

static union {

	struct bpf_ctx_convert {

#define BPF_PROG_TYPE(_id, _name, prog_ctx_type, kern_ctx_type) \
@@ -3508,6 +3509,7 @@ static u8 bpf_ctx_convert_map[] = { 
	0, /* avoid empty array */

};

#undef BPF_MAP_TYPE

#undef BPF_LINK_TYPE



static const struct btf_member *

btf_get_prog_ctx_type(struct bpf_verifier_log *log, struct btf *btf,

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