Adding upstream version 255.4.upstream/255.4

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 43 insertions, 0 deletions

diff --git a/src/shared/bpf-link.c b/src/shared/bpf-link.c
new file mode 100644
index 0000000..fea49b2
--- /dev/null
+++ b/src/shared/bpf-link.c
@@ -0,0 +1,43 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include "bpf-dlopen.h"
+#include "bpf-link.h"
+#include "serialize.h"
+
+bool bpf_can_link_program(struct bpf_program *prog) {
+        _cleanup_(bpf_link_freep) struct bpf_link *link = NULL;
+
+        assert(prog);
+
+        if (dlopen_bpf() < 0)
+                return false;
+
+        /* Pass invalid cgroup fd intentionally. */
+        link = sym_bpf_program__attach_cgroup(prog, /*cgroup_fd=*/-1);
+
+        /* EBADF indicates that bpf_link is supported by kernel. */
+        return sym_libbpf_get_error(link) == -EBADF;
+}
+
+int bpf_serialize_link(FILE *f, FDSet *fds, const char *key, struct bpf_link *link) {
+        assert(key);
+
+        if (!link)
+                return -ENOENT;
+
+        if (sym_libbpf_get_error(link) != 0)
+                return -EINVAL;
+
+        return serialize_fd(f, fds, key, sym_bpf_link__fd(link));
+}
+
+struct bpf_link *bpf_link_free(struct bpf_link *link) {
+        /* If libbpf wasn't dlopen()ed, sym_bpf_link__destroy might be unresolved (NULL), so let's not try to
+         * call it if link is NULL. link might also be a non-null "error pointer", but such a value can only
+         * originate from a call to libbpf, but that means that libbpf is available, and we can let
+         * bpf_link__destroy() handle it. */
+        if (link)
+                (void) sym_bpf_link__destroy(link);
+
+        return NULL;
+}