Introduce bpf_link_get_fd_by_id_opts(), to let the caller specify the
needed permissions for the operation. Keep the existing
bpf_link_get_fd_by_id(), to request read-write permissions.
Currently, setting permissions in the data structure has no effect, as the
kernel does not evaluate them. The new variant has been introduced anyway
for symmetry with bpf_map_get_fd_by_id_opts(). Evaluating permissions could
be done in future kernel versions.
Signed-off-by: Roberto Sassu <roberto.sassu@xxxxxxxxxx>
---
tools/lib/bpf/bpf.c | 13 ++++++++++++-
tools/lib/bpf/bpf.h | 2 ++
tools/lib/bpf/libbpf.map | 1 +
3 files changed, 15 insertions(+), 1 deletion(-)
diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
index b131bbc8509e..5f2785a4c358 100644
--- a/tools/lib/bpf/bpf.c
+++ b/tools/lib/bpf/bpf.c
@@ -1002,18 +1002,29 @@ int bpf_btf_get_fd_by_id(__u32 id)
return bpf_btf_get_fd_by_id_opts(id, NULL);
}
-int bpf_link_get_fd_by_id(__u32 id)
+int bpf_link_get_fd_by_id_opts(__u32 id,
+ const struct bpf_get_fd_opts *opts)
{
union bpf_attr attr;
int fd;
+ if (!OPTS_VALID(opts, bpf_get_fd_opts))
+ return libbpf_err(-EINVAL);
+
memset(&attr, 0, sizeof(attr));
attr.link_id = id;
+ if (kernel_supports(NULL, FEAT_GET_FD_BY_ID_OPEN_FLAGS))
+ attr.open_flags = OPTS_GET(opts, flags, 0);
fd = sys_bpf_fd(BPF_LINK_GET_FD_BY_ID, &attr, sizeof(attr));
return libbpf_err_errno(fd);
}
+int bpf_link_get_fd_by_id(__u32 id)
+{
+ return bpf_link_get_fd_by_id_opts(id, NULL);
+}
+
int bpf_obj_get_info_by_fd(int bpf_fd, void *info, __u32 *info_len)
{
union bpf_attr attr;
diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h
index 45d3739d901f..b75fd9d37bad 100644
--- a/tools/lib/bpf/bpf.h
+++ b/tools/lib/bpf/bpf.h
@@ -372,6 +372,8 @@ LIBBPF_API int bpf_map_get_fd_by_id(__u32 id);
LIBBPF_API int bpf_btf_get_fd_by_id_opts(__u32 id,
const struct bpf_get_fd_opts *opts);
LIBBPF_API int bpf_btf_get_fd_by_id(__u32 id);
+LIBBPF_API int bpf_link_get_fd_by_id_opts(__u32 id,
+ const struct bpf_get_fd_opts *opts);
LIBBPF_API int bpf_link_get_fd_by_id(__u32 id);
LIBBPF_API int bpf_obj_get_info_by_fd(int bpf_fd, void *info, __u32 *info_len);
diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index ee6755dbf004..dba97d2ef8a9 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -367,4 +367,5 @@ LIBBPF_1.0.0 {
bpf_prog_get_fd_by_id_opts;
bpf_map_get_fd_by_id_opts;
bpf_btf_get_fd_by_id_opts;
+ bpf_link_get_fd_by_id_opts;
};
--
2.25.1
