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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2020 Google LLC.
*/
#include <test_progs.h>
#include <linux/limits.h>
#include "bprm_opts.skel.h"
#include "network_helpers.h"
#include "task_local_storage_helpers.h"
static const char * const bash_envp[] = { "TMPDIR=shouldnotbeset", NULL };
static int update_storage(int map_fd, int secureexec)
{
int task_fd, ret = 0;
task_fd = sys_pidfd_open(getpid(), 0);
if (task_fd < 0)
return errno;
ret = bpf_map_update_elem(map_fd, &task_fd, &secureexec, BPF_NOEXIST);
if (ret)
ret = errno;
close(task_fd);
return ret;
}
static int run_set_secureexec(int map_fd, int secureexec)
{
int child_pid, child_status, ret, null_fd;
child_pid = fork();
if (child_pid == 0) {
null_fd = open("/dev/null", O_WRONLY);
if (null_fd == -1)
exit(errno);
dup2(null_fd, STDOUT_FILENO);
dup2(null_fd, STDERR_FILENO);
close(null_fd);
/* Ensure that all executions from hereon are
* secure by setting a local storage which is read by
* the bprm_creds_for_exec hook and sets bprm->secureexec.
*/
ret = update_storage(map_fd, secureexec);
if (ret)
exit(ret);
/* If the binary is executed with securexec=1, the dynamic
* loader ingores and unsets certain variables like LD_PRELOAD,
* TMPDIR etc. TMPDIR is used here to simplify the example, as
* LD_PRELOAD requires a real .so file.
*
* If the value of TMPDIR is set, the bash command returns 10
* and if the value is unset, it returns 20.
*/
execle("/bin/bash", "bash", "-c",
"[[ -z \"${TMPDIR}\" ]] || exit 10 && exit 20", NULL,
bash_envp);
exit(errno);
} else if (child_pid > 0) {
waitpid(child_pid, &child_status, 0);
ret = WEXITSTATUS(child_status);
/* If a secureexec occurred, the exit status should be 20 */
if (secureexec && ret == 20)
return 0;
/* If normal execution happened, the exit code should be 10 */
if (!secureexec && ret == 10)
return 0;
}
return -EINVAL;
}
void test_test_bprm_opts(void)
{
int err, duration = 0;
struct bprm_opts *skel = NULL;
skel = bprm_opts__open_and_load();
if (CHECK(!skel, "skel_load", "skeleton failed\n"))
goto close_prog;
err = bprm_opts__attach(skel);
if (CHECK(err, "attach", "attach failed: %d\n", err))
goto close_prog;
/* Run the test with the secureexec bit unset */
err = run_set_secureexec(bpf_map__fd(skel->maps.secure_exec_task_map),
0 /* secureexec */);
if (CHECK(err, "run_set_secureexec:0", "err = %d\n", err))
goto close_prog;
/* Run the test with the secureexec bit set */
err = run_set_secureexec(bpf_map__fd(skel->maps.secure_exec_task_map),
1 /* secureexec */);
if (CHECK(err, "run_set_secureexec:1", "err = %d\n", err))
goto close_prog;
close_prog:
bprm_opts__destroy(skel);
}
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