// 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 ignores 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);
}