Add tests for bpf path iterator, including test cases similar to real
workload (call bpf_path_d_path and bpf_get_dentry_xattr), and test cases
where the verifier rejects invalid use of the iterator.
Signed-off-by: Song Liu <song@xxxxxxxxxx>
---
.../testing/selftests/bpf/bpf_experimental.h | 6 +
.../selftests/bpf/prog_tests/path_iter.c | 12 ++
tools/testing/selftests/bpf/progs/path_iter.c | 145 ++++++++++++++++++
3 files changed, 163 insertions(+)
create mode 100644 tools/testing/selftests/bpf/prog_tests/path_iter.c
create mode 100644 tools/testing/selftests/bpf/progs/path_iter.c
diff --git a/tools/testing/selftests/bpf/bpf_experimental.h b/tools/testing/selftests/bpf/bpf_experimental.h
index 5e512a1d09d1..cbb759b473df 100644
--- a/tools/testing/selftests/bpf/bpf_experimental.h
+++ b/tools/testing/selftests/bpf/bpf_experimental.h
@@ -596,4 +596,10 @@ extern int bpf_iter_dmabuf_new(struct bpf_iter_dmabuf *it) __weak __ksym;
extern struct dma_buf *bpf_iter_dmabuf_next(struct bpf_iter_dmabuf *it) __weak __ksym;
extern void bpf_iter_dmabuf_destroy(struct bpf_iter_dmabuf *it) __weak __ksym;
+struct bpf_iter_path;
+extern int bpf_iter_path_new(struct bpf_iter_path *it, struct path *start,
+ __u64 flags) __weak __ksym;
+extern struct path *bpf_iter_path_next(struct bpf_iter_path *it) __weak __ksym;
+extern void bpf_iter_path_destroy(struct bpf_iter_path *it) __weak __ksym;
+
#endif
diff --git a/tools/testing/selftests/bpf/prog_tests/path_iter.c b/tools/testing/selftests/bpf/prog_tests/path_iter.c
new file mode 100644
index 000000000000..3c99c24fbd96
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/path_iter.c
@@ -0,0 +1,12 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2025 Meta Platforms, Inc. and affiliates. */
+
+#include <test_progs.h>
+#include <bpf/libbpf.h>
+#include <bpf/btf.h>
+#include "path_iter.skel.h"
+
+void test_path_iter(void)
+{
+ RUN_TESTS(path_iter);
+}
diff --git a/tools/testing/selftests/bpf/progs/path_iter.c b/tools/testing/selftests/bpf/progs/path_iter.c
new file mode 100644
index 000000000000..74d0f4e19ffa
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/path_iter.c
@@ -0,0 +1,145 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2025 Meta Platforms, Inc. and affiliates. */
+
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+#include "bpf_misc.h"
+#include "bpf_experimental.h"
+
+char _license[] SEC("license") = "GPL";
+
+char path_name[256];
+char xattr_val[64];
+
+static __always_inline void access_path_dentry(struct path *p)
+{
+ struct bpf_dynptr ptr;
+ struct dentry *dentry;
+
+ if (!p)
+ return;
+
+ bpf_dynptr_from_mem(xattr_val, sizeof(xattr_val), 0, &ptr);
+ bpf_path_d_path(p, path_name, sizeof(path_name));
+
+ dentry = p->dentry;
+ if (dentry)
+ bpf_get_dentry_xattr(dentry, "user.xattr", &ptr);
+}
+
+SEC("lsm.s/file_open")
+__success
+int BPF_PROG(open_code, struct file *f)
+{
+ struct bpf_iter_path path_it;
+ struct path *p;
+ int ret;
+
+ ret = bpf_iter_path_new(&path_it, &f->f_path, 0);
+ if (ret) {
+ bpf_iter_path_destroy(&path_it);
+ return 0;
+ }
+
+ p = bpf_iter_path_next(&path_it);
+ access_path_dentry(p);
+ bpf_iter_path_destroy(&path_it);
+
+ return 0;
+}
+
+SEC("lsm.s/file_open")
+__success
+int BPF_PROG(for_each, struct file *f)
+{
+ struct path *p;
+
+ bpf_for_each(path, p, &f->f_path, 0)
+ access_path_dentry(p);
+
+ return 0;
+}
+
+SEC("lsm.s/file_open")
+__failure __msg("Unreleased reference")
+int BPF_PROG(missing_destroy, struct file *f)
+{
+ struct bpf_iter_path path_it;
+
+ bpf_iter_path_new(&path_it, &f->f_path, 0);
+
+ return 0;
+}
+
+SEC("lsm.s/file_open")
+__failure __msg("expected an initialized iter_path")
+int BPF_PROG(missing_new, struct file *f)
+{
+ struct bpf_iter_path path_it;
+
+ bpf_iter_path_destroy(&path_it);
+ return 0;
+}
+
+SEC("lsm.s/file_open")
+__failure __msg("expected uninitialized iter_path")
+int BPF_PROG(new_twice, struct file *f)
+{
+ struct bpf_iter_path path_it;
+
+ bpf_iter_path_new(&path_it, &f->f_path, 0);
+ bpf_iter_path_new(&path_it, &f->f_path, 0);
+ bpf_iter_path_destroy(&path_it);
+ return 0;
+}
+
+SEC("lsm.s/file_open")
+__failure __msg("expected an initialized iter_path")
+int BPF_PROG(destroy_twice, struct file *f)
+{
+ struct bpf_iter_path path_it;
+
+ bpf_iter_path_new(&path_it, &f->f_path, 0);
+ bpf_iter_path_destroy(&path_it);
+ bpf_iter_path_destroy(&path_it);
+ return 0;
+}
+
+SEC("lsm.s/file_open")
+__success
+int BPF_PROG(reuse_path_iter, struct file *f)
+{
+ struct bpf_iter_path path_it;
+
+ bpf_iter_path_new(&path_it, &f->f_path, 0);
+ bpf_iter_path_destroy(&path_it);
+ bpf_iter_path_new(&path_it, &f->f_path, 0);
+ bpf_iter_path_destroy(&path_it);
+ return 0;
+}
+
+SEC("lsm.s/file_open")
+__failure __msg("invalid read from stack off")
+int BPF_PROG(invalid_read_path_iter, struct file *f)
+{
+ struct bpf_iter_path path_it;
+ struct bpf_iter_path path_it_2;
+
+
+ bpf_iter_path_new(&path_it, &f->f_path, 0);
+ path_it_2 = path_it;
+ bpf_iter_path_destroy(&path_it_2);
+ return 0;
+}
+
+SEC("lsm.s/sb_alloc_security")
+__failure __msg("must be referenced or trusted")
+int BPF_PROG(untrusted_path, struct super_block *sb)
+{
+ struct bpf_iter_path path_it;
+
+ bpf_iter_path_new(&path_it, &sb->s_bdev_file->f_path, 0);
+ bpf_iter_path_destroy(&path_it);
+ return 0;
+}
--
2.47.1
