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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: Martin KaFai Lau <kafai@fb.com>
Acked-by: Alexei Starovoitov <ast@fb.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This commit is contained in:
Martin KaFai Lau 2018-05-04 14:49:52 -07:00 committed by Daniel Borkmann
parent 78958fca7e
commit 62dab84c81
3 changed files with 43 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
include/uapi/linux/bpf.h
View File

@ -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).

26
kernel/bpf/btf.c
View File

@ -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;

17
kernel/bpf/syscall.c
View File

@ -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;