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") 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