From: Mykyta Yatsenko <yatsenko@xxxxxxxx>
Add selftests to verify that it is possible to load freplace program
from user namespace if BPF token is initialized by bpf_object__prepare
before calling bpf_program__set_attach_target.
Negative test is added as well.
Signed-off-by: Mykyta Yatsenko <yatsenko@xxxxxxxx>
---
.../testing/selftests/bpf/prog_tests/token.c | 94 +++++++++++++++++++
.../selftests/bpf/progs/priv_freplace_prog.c | 13 +++
tools/testing/selftests/bpf/progs/priv_prog.c | 4 +-
3 files changed, 109 insertions(+), 2 deletions(-)
create mode 100644 tools/testing/selftests/bpf/progs/priv_freplace_prog.c
diff --git a/tools/testing/selftests/bpf/prog_tests/token.c b/tools/testing/selftests/bpf/prog_tests/token.c
index c3ab9b6fb069..38f405b8a2c5 100644
--- a/tools/testing/selftests/bpf/prog_tests/token.c
+++ b/tools/testing/selftests/bpf/prog_tests/token.c
@@ -19,6 +19,7 @@
#include "priv_prog.skel.h"
#include "dummy_st_ops_success.skel.h"
#include "token_lsm.skel.h"
+#include "priv_freplace_prog.skel.h"
static inline int sys_mount(const char *dev_name, const char *dir_name,
const char *type, unsigned long flags,
@@ -788,6 +789,83 @@ static int userns_obj_priv_prog(int mnt_fd, struct token_lsm *lsm_skel)
return 0;
}
+static int userns_obj_priv_freplace_setup(int mnt_fd, struct priv_freplace_prog **fr_skel,
+ struct priv_prog **skel, int *tgt_fd)
+{
+ LIBBPF_OPTS(bpf_object_open_opts, opts);
+ int err;
+ char buf[256];
+
+ /* use bpf_token_path to provide BPF FS path */
+ snprintf(buf, sizeof(buf), "/proc/self/fd/%d", mnt_fd);
+ opts.bpf_token_path = buf;
+ *skel = priv_prog__open_opts(&opts);
+ if (!ASSERT_OK_PTR(*skel, "priv_prog__open_opts"))
+ return -EINVAL;
+ err = priv_prog__load(*skel);
+ if (!ASSERT_OK(err, "priv_prog__load"))
+ return -EINVAL;
+
+ *fr_skel = priv_freplace_prog__open_opts(&opts);
+ if (!ASSERT_OK_PTR(*skel, "priv_freplace_prog__open_opts"))
+ return -EINVAL;
+
+ *tgt_fd = bpf_program__fd((*skel)->progs.kprobe_prog);
+ return 0;
+}
+
+/* Verify that freplace works from user namespace, because bpf token is loaded
+ * in bpf_object__prepare
+ */
+static int userns_obj_priv_freplace_prog(int mnt_fd, struct token_lsm *lsm_skel)
+{
+ struct priv_freplace_prog *fr_skel = NULL;
+ struct priv_prog *skel = NULL;
+ int err, tgt_fd;
+
+ err = userns_obj_priv_freplace_setup(mnt_fd, &fr_skel, &skel, &tgt_fd);
+ if (!ASSERT_OK(err, "setup"))
+ goto out;
+
+ err = bpf_object__prepare(fr_skel->obj);
+ if (!ASSERT_OK(err, "freplace__prepare"))
+ goto out;
+
+ err = bpf_program__set_attach_target(fr_skel->progs.new_kprobe_prog, tgt_fd, "kprobe_prog");
+ if (err)
+ goto out;
+
+ err = priv_freplace_prog__load(fr_skel);
+ ASSERT_OK(err, "priv_freplace_prog__load");
+out:
+ priv_freplace_prog__destroy(fr_skel);
+ priv_prog__destroy(skel);
+ return err;
+}
+
+/* Verify that replace fails to set attach target from user namespace without bpf token */
+static int userns_obj_priv_freplace_prog_fail(int mnt_fd, struct token_lsm *lsm_skel)
+{
+ struct priv_freplace_prog *fr_skel = NULL;
+ struct priv_prog *skel = NULL;
+ int err, tgt_fd;
+
+ err = userns_obj_priv_freplace_setup(mnt_fd, &fr_skel, &skel, &tgt_fd);
+ if (!ASSERT_OK(err, "setup"))
+ goto out;
+
+ err = bpf_program__set_attach_target(fr_skel->progs.new_kprobe_prog, tgt_fd, "kprobe_prog");
+ if (ASSERT_ERR(err, "attach fails"))
+ err = 0;
+ else
+ err = -EINVAL;
+
+out:
+ priv_freplace_prog__destroy(fr_skel);
+ priv_prog__destroy(skel);
+ return err;
+}
+
/* this test is called with BPF FS that doesn't delegate BPF_BTF_LOAD command,
* which should cause struct_ops application to fail, as BTF won't be uploaded
* into the kernel, even if STRUCT_OPS programs themselves are allowed
@@ -1010,6 +1088,22 @@ void test_token(void)
subtest_userns(&opts, userns_obj_priv_prog);
}
+ if (test__start_subtest("obj_priv_freplace_prog")) {
+ struct bpffs_opts opts = {
+ .cmds = bit(BPF_BTF_LOAD) | bit(BPF_PROG_LOAD),
+ .progs = bit(BPF_PROG_TYPE_KPROBE) | bit(BPF_PROG_TYPE_EXT),
+ .attachs = ~0ULL,
+ };
+ subtest_userns(&opts, userns_obj_priv_freplace_prog);
+ }
+ if (test__start_subtest("obj_priv_freplace_prog_fail")) {
+ struct bpffs_opts opts = {
+ .cmds = bit(BPF_BTF_LOAD) | bit(BPF_PROG_LOAD),
+ .progs = bit(BPF_PROG_TYPE_KPROBE) | bit(BPF_PROG_TYPE_EXT),
+ .attachs = ~0ULL,
+ };
+ subtest_userns(&opts, userns_obj_priv_freplace_prog_fail);
+ }
if (test__start_subtest("obj_priv_btf_fail")) {
struct bpffs_opts opts = {
/* disallow BTF loading */
diff --git a/tools/testing/selftests/bpf/progs/priv_freplace_prog.c b/tools/testing/selftests/bpf/progs/priv_freplace_prog.c
new file mode 100644
index 000000000000..c9ab81988624
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/priv_freplace_prog.c
@@ -0,0 +1,13 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2025 Meta Platforms, Inc. and affiliates. */
+
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+
+char _license[] SEC("license") = "GPL";
+
+SEC("freplace/kprobe_prog")
+int new_kprobe_prog(struct pt_regs *ctx)
+{
+ return 1;
+}
diff --git a/tools/testing/selftests/bpf/progs/priv_prog.c b/tools/testing/selftests/bpf/progs/priv_prog.c
index 3c7b2b618c8a..be9deda38b52 100644
--- a/tools/testing/selftests/bpf/progs/priv_prog.c
+++ b/tools/testing/selftests/bpf/progs/priv_prog.c
@@ -1,5 +1,5 @@
// SPDX-License-Identifier: GPL-2.0
-/* Copyright (c) 2023 Meta Platforms, Inc. and affiliates. */
+/* Copyright (c) 2025 Meta Platforms, Inc. and affiliates. */
#include "vmlinux.h"
#include <bpf/bpf_helpers.h>
@@ -7,7 +7,7 @@
char _license[] SEC("license") = "GPL";
SEC("kprobe")
-int kprobe_prog(void *ctx)
+int kprobe_prog(struct pt_regs *ctx)
{
return 1;
}
--
2.48.1
