1 // SPDX-License-Identifier: GPL-2.0
2 /* Copyright (c) 2025 Meta Platforms, Inc. and affiliates. */
3
4 #include <vmlinux.h>
5 #include <bpf/bpf_tracing.h>
6 #include <bpf/bpf_helpers.h>
7 #include <bpf/bpf_core_read.h>
8 #include "bpf_experimental.h"
9
10 char _license[] SEC("license") = "GPL";
11
12 pid_t target_pid = 0;
13
14 char xattr_value[64];
15 static const char expected_value_a[] = "bpf_selftest_value_a";
16 static const char expected_value_b[] = "bpf_selftest_value_b";
17 bool found_value_a;
18 bool found_value_b;
19
20 SEC("lsm.s/file_open")
BPF_PROG(test_file_open)21 int BPF_PROG(test_file_open)
22 {
23 u64 cgrp_id = bpf_get_current_cgroup_id();
24 struct cgroup_subsys_state *css, *tmp;
25 struct bpf_dynptr value_ptr;
26 struct cgroup *cgrp;
27
28 if ((bpf_get_current_pid_tgid() >> 32) != target_pid)
29 return 0;
30
31 bpf_rcu_read_lock();
32 cgrp = bpf_cgroup_from_id(cgrp_id);
33 if (!cgrp) {
34 bpf_rcu_read_unlock();
35 return 0;
36 }
37
38 css = &cgrp->self;
39 bpf_dynptr_from_mem(xattr_value, sizeof(xattr_value), 0, &value_ptr);
40 bpf_for_each(css, tmp, css, BPF_CGROUP_ITER_ANCESTORS_UP) {
41 int ret;
42
43 ret = bpf_cgroup_read_xattr(tmp->cgroup, "user.bpf_test",
44 &value_ptr);
45 if (ret < 0)
46 continue;
47
48 if (ret == sizeof(expected_value_a) &&
49 !bpf_strncmp(xattr_value, sizeof(expected_value_a), expected_value_a))
50 found_value_a = true;
51 if (ret == sizeof(expected_value_b) &&
52 !bpf_strncmp(xattr_value, sizeof(expected_value_b), expected_value_b))
53 found_value_b = true;
54 }
55
56 bpf_rcu_read_unlock();
57 bpf_cgroup_release(cgrp);
58
59 return 0;
60 }
61