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1// SPDX-License-Identifier: GPL-2.02 3/*4 * Copyright (C) 2020 Google LLC.5 */6 7#include <test_progs.h>8#include <linux/limits.h>9 10#include "bprm_opts.skel.h"11#include "network_helpers.h"12#include "task_local_storage_helpers.h"13 14static const char * const bash_envp[] = { "TMPDIR=shouldnotbeset", NULL };15 16static int update_storage(int map_fd, int secureexec)17{18 int task_fd, ret = 0;19 20 task_fd = sys_pidfd_open(getpid(), 0);21 if (task_fd < 0)22 return errno;23 24 ret = bpf_map_update_elem(map_fd, &task_fd, &secureexec, BPF_NOEXIST);25 if (ret)26 ret = errno;27 28 close(task_fd);29 return ret;30}31 32static int run_set_secureexec(int map_fd, int secureexec)33{34 int child_pid, child_status, ret, null_fd;35 36 child_pid = fork();37 if (child_pid == 0) {38 null_fd = open("/dev/null", O_WRONLY);39 if (null_fd == -1)40 exit(errno);41 dup2(null_fd, STDOUT_FILENO);42 dup2(null_fd, STDERR_FILENO);43 close(null_fd);44 45 /* Ensure that all executions from hereon are46 * secure by setting a local storage which is read by47 * the bprm_creds_for_exec hook and sets bprm->secureexec.48 */49 ret = update_storage(map_fd, secureexec);50 if (ret)51 exit(ret);52 53 /* If the binary is executed with securexec=1, the dynamic54 * loader ignores and unsets certain variables like LD_PRELOAD,55 * TMPDIR etc. TMPDIR is used here to simplify the example, as56 * LD_PRELOAD requires a real .so file.57 *58 * If the value of TMPDIR is set, the bash command returns 1059 * and if the value is unset, it returns 20.60 */61 execle("/bin/bash", "bash", "-c",62 "[[ -z \"${TMPDIR}\" ]] || exit 10 && exit 20", NULL,63 bash_envp);64 exit(errno);65 } else if (child_pid > 0) {66 waitpid(child_pid, &child_status, 0);67 ret = WEXITSTATUS(child_status);68 69 /* If a secureexec occurred, the exit status should be 20 */70 if (secureexec && ret == 20)71 return 0;72 73 /* If normal execution happened, the exit code should be 10 */74 if (!secureexec && ret == 10)75 return 0;76 }77 78 return -EINVAL;79}80 81void test_test_bprm_opts(void)82{83 int err, duration = 0;84 struct bprm_opts *skel = NULL;85 86 skel = bprm_opts__open_and_load();87 if (CHECK(!skel, "skel_load", "skeleton failed\n"))88 goto close_prog;89 90 err = bprm_opts__attach(skel);91 if (CHECK(err, "attach", "attach failed: %d\n", err))92 goto close_prog;93 94 /* Run the test with the secureexec bit unset */95 err = run_set_secureexec(bpf_map__fd(skel->maps.secure_exec_task_map),96 0 /* secureexec */);97 if (CHECK(err, "run_set_secureexec:0", "err = %d\n", err))98 goto close_prog;99 100 /* Run the test with the secureexec bit set */101 err = run_set_secureexec(bpf_map__fd(skel->maps.secure_exec_task_map),102 1 /* secureexec */);103 if (CHECK(err, "run_set_secureexec:1", "err = %d\n", err))104 goto close_prog;105 106close_prog:107 bprm_opts__destroy(skel);108}109