Commit 62dab84c authored by Martin KaFai Lau's avatar Martin KaFai Lau Committed by Daniel Borkmann
Browse files

bpf: btf: Add struct bpf_btf_info 



During BPF_OBJ_GET_INFO_BY_FD on a btf_fd, the current bpf_attr's
info.info is directly filled with the BTF binary data.  It is
not extensible.  In this case, we want to add BTF ID.

This patch adds "struct bpf_btf_info" which has the BTF ID as
one of its member.  The BTF binary data itself is exposed through
the "btf" and "btf_size" members.

Signed-off-by: default avatarMartin KaFai Lau <kafai@fb.com>
Acked-by: default avatarAlexei Starovoitov <ast@fb.com>
Acked-by: default avatarSong Liu <songliubraving@fb.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
parent 78958fca

include/uapi/linux/bpf.h

+6 −0
Original line number Diff line number Diff line
@@ -2137,6 +2137,12 @@ struct bpf_map_info { 
	__u32 btf_value_id;

} __attribute__((aligned(8)));



struct bpf_btf_info {

	__aligned_u64 btf;

	__u32 btf_size;

	__u32 id;

} __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

+21 −5
Original line number Diff line number Diff line
@@ -2114,12 +2114,28 @@ int btf_get_info_by_fd(const struct btf *btf, 
		       const union bpf_attr *attr,

		       union bpf_attr __user *uattr)

{

	void __user *udata = u64_to_user_ptr(attr->info.info);

	u32 copy_len = min_t(u32, btf->data_size,

			     attr->info.info_len);

	struct bpf_btf_info __user *uinfo;

	struct bpf_btf_info info = {};

	u32 info_copy, btf_copy;

	void __user *ubtf;

	u32 uinfo_len;



	if (copy_to_user(udata, btf->data, copy_len) ||

	    put_user(btf->data_size, &uattr->info.info_len))

	uinfo = u64_to_user_ptr(attr->info.info);

	uinfo_len = attr->info.info_len;



	info_copy = min_t(u32, uinfo_len, sizeof(info));

	if (copy_from_user(&info, uinfo, info_copy))

		return -EFAULT;



	info.id = btf->id;

	ubtf = u64_to_user_ptr(info.btf);

	btf_copy = min_t(u32, btf->data_size, info.btf_size);

	if (copy_to_user(ubtf, btf->data, btf_copy))

		return -EFAULT;

	info.btf_size = btf->data_size;



	if (copy_to_user(uinfo, &info, info_copy) ||

	    put_user(info_copy, &uattr->info.info_len))

		return -EFAULT;



	return 0;

kernel/bpf/syscall.c

+16 −1
Original line number Diff line number Diff line
@@ -2021,6 +2021,21 @@ static int bpf_map_get_info_by_fd(struct bpf_map *map, 
	return 0;

}



static int bpf_btf_get_info_by_fd(struct btf *btf,

				  const union bpf_attr *attr,

				  union bpf_attr __user *uattr)

{

	struct bpf_btf_info __user *uinfo = u64_to_user_ptr(attr->info.info);

	u32 info_len = attr->info.info_len;

	int err;



	err = check_uarg_tail_zero(uinfo, sizeof(*uinfo), info_len);

	if (err)

		return err;



	return btf_get_info_by_fd(btf, attr, uattr);

}



#define BPF_OBJ_GET_INFO_BY_FD_LAST_FIELD info.info



static int bpf_obj_get_info_by_fd(const union bpf_attr *attr,
@@ -2044,7 +2059,7 @@ static int bpf_obj_get_info_by_fd(const union bpf_attr *attr, 
		err = bpf_map_get_info_by_fd(f.file->private_data, attr,

					     uattr);

	else if (f.file->f_op == &btf_fops)

		err = btf_get_info_by_fd(f.file->private_data, attr, uattr);

		err = bpf_btf_get_info_by_fd(f.file->private_data, attr, uattr);

	else

		err = -EINVAL;

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