Commit cdbee383 authored by Andrey Ignatov's avatar Andrey Ignatov Committed by Alexei Starovoitov
Browse files

libbpf: Introduce bpf_prog_attach_xattr 



Introduce a new bpf_prog_attach_xattr function that, in addition to
program fd, target fd and attach type, accepts an extendable struct
bpf_prog_attach_opts.

bpf_prog_attach_opts relies on DECLARE_LIBBPF_OPTS macro to maintain
backward and forward compatibility and has the following "optional"
attach attributes:

* existing attach_flags, since it's not required when attaching in NONE
  mode. Even though it's quite often used in MULTI and OVERRIDE mode it
  seems to be a good idea to reduce number of arguments to
  bpf_prog_attach_xattr;

* newly introduced attribute of BPF_PROG_ATTACH command: replace_prog_fd
  that is fd of previously attached cgroup-bpf program to replace if
  BPF_F_REPLACE flag is used.

The new function is named to be consistent with other xattr-functions
(bpf_prog_test_run_xattr, bpf_create_map_xattr, bpf_load_program_xattr).

The struct bpf_prog_attach_opts is supposed to be used with
DECLARE_LIBBPF_OPTS macro.

Signed-off-by: default avatarAndrey Ignatov <rdna@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/bd6e0732303eb14e4b79cb128268d9e9ad6db208.1576741281.git.rdna@fb.com
parent 7dd68b32

tools/lib/bpf/bpf.c

+16 −1
Original line number Diff line number Diff line
@@ -466,14 +466,29 @@ int bpf_obj_get(const char *pathname) 


int bpf_prog_attach(int prog_fd, int target_fd, enum bpf_attach_type type,

		    unsigned int flags)

{

	DECLARE_LIBBPF_OPTS(bpf_prog_attach_opts, opts,

		.flags = flags,

	);



	return bpf_prog_attach_xattr(prog_fd, target_fd, type, &opts);

}



int bpf_prog_attach_xattr(int prog_fd, int target_fd,

			  enum bpf_attach_type type,

			  const struct bpf_prog_attach_opts *opts)

{

	union bpf_attr attr;



	if (!OPTS_VALID(opts, bpf_prog_attach_opts))

		return -EINVAL;



	memset(&attr, 0, sizeof(attr));

	attr.target_fd	   = target_fd;

	attr.attach_bpf_fd = prog_fd;

	attr.attach_type   = type;

	attr.attach_flags  = flags;

	attr.attach_flags  = OPTS_GET(opts, flags, 0);

	attr.replace_bpf_fd = OPTS_GET(opts, replace_prog_fd, 0);



	return sys_bpf(BPF_PROG_ATTACH, &attr, sizeof(attr));

}

tools/lib/bpf/bpf.h

+11 −0
Original line number Diff line number Diff line
@@ -126,8 +126,19 @@ LIBBPF_API int bpf_map_get_next_key(int fd, const void *key, void *next_key); 
LIBBPF_API int bpf_map_freeze(int fd);

LIBBPF_API int bpf_obj_pin(int fd, const char *pathname);

LIBBPF_API int bpf_obj_get(const char *pathname);



struct bpf_prog_attach_opts {

	size_t sz; /* size of this struct for forward/backward compatibility */

	unsigned int flags;

	int replace_prog_fd;

};

#define bpf_prog_attach_opts__last_field replace_prog_fd



LIBBPF_API int bpf_prog_attach(int prog_fd, int attachable_fd,

			       enum bpf_attach_type type, unsigned int flags);

LIBBPF_API int bpf_prog_attach_xattr(int prog_fd, int attachable_fd,

				     enum bpf_attach_type type,

				     const struct bpf_prog_attach_opts *opts);

LIBBPF_API int bpf_prog_detach(int attachable_fd, enum bpf_attach_type type);

LIBBPF_API int bpf_prog_detach2(int prog_fd, int attachable_fd,

				enum bpf_attach_type type);

tools/lib/bpf/libbpf.map

+1 −0
Original line number Diff line number Diff line
@@ -219,6 +219,7 @@ LIBBPF_0.0.7 { 
		bpf_object__detach_skeleton;

		bpf_object__load_skeleton;

		bpf_object__open_skeleton;

		bpf_prog_attach_xattr;

		bpf_program__attach;

		bpf_program__name;

		btf__align_of;

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