cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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test_bprm_opts.c (2915B)

      1// SPDX-License-Identifier: GPL-2.0
      2
      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
     13#ifndef __NR_pidfd_open
     14#define __NR_pidfd_open 434
     15#endif
     16
     17static const char * const bash_envp[] = { "TMPDIR=shouldnotbeset", NULL };
     18
     19static inline int sys_pidfd_open(pid_t pid, unsigned int flags)
     20{
     21	return syscall(__NR_pidfd_open, pid, flags);
     22}
     23
     24static int update_storage(int map_fd, int secureexec)
     25{
     26	int task_fd, ret = 0;
     27
     28	task_fd = sys_pidfd_open(getpid(), 0);
     29	if (task_fd < 0)
     30		return errno;
     31
     32	ret = bpf_map_update_elem(map_fd, &task_fd, &secureexec, BPF_NOEXIST);
     33	if (ret)
     34		ret = errno;
     35
     36	close(task_fd);
     37	return ret;
     38}
     39
     40static int run_set_secureexec(int map_fd, int secureexec)
     41{
     42	int child_pid, child_status, ret, null_fd;
     43
     44	child_pid = fork();
     45	if (child_pid == 0) {
     46		null_fd = open("/dev/null", O_WRONLY);
     47		if (null_fd == -1)
     48			exit(errno);
     49		dup2(null_fd, STDOUT_FILENO);
     50		dup2(null_fd, STDERR_FILENO);
     51		close(null_fd);
     52
     53		/* Ensure that all executions from hereon are
     54		 * secure by setting a local storage which is read by
     55		 * the bprm_creds_for_exec hook and sets bprm->secureexec.
     56		 */
     57		ret = update_storage(map_fd, secureexec);
     58		if (ret)
     59			exit(ret);
     60
     61		/* If the binary is executed with securexec=1, the dynamic
     62		 * loader ingores and unsets certain variables like LD_PRELOAD,
     63		 * TMPDIR etc. TMPDIR is used here to simplify the example, as
     64		 * LD_PRELOAD requires a real .so file.
     65		 *
     66		 * If the value of TMPDIR is set, the bash command returns 10
     67		 * and if the value is unset, it returns 20.
     68		 */
     69		execle("/bin/bash", "bash", "-c",
     70		       "[[ -z \"${TMPDIR}\" ]] || exit 10 && exit 20", NULL,
     71		       bash_envp);
     72		exit(errno);
     73	} else if (child_pid > 0) {
     74		waitpid(child_pid, &child_status, 0);
     75		ret = WEXITSTATUS(child_status);
     76
     77		/* If a secureexec occurred, the exit status should be 20 */
     78		if (secureexec && ret == 20)
     79			return 0;
     80
     81		/* If normal execution happened, the exit code should be 10 */
     82		if (!secureexec && ret == 10)
     83			return 0;
     84	}
     85
     86	return -EINVAL;
     87}
     88
     89void test_test_bprm_opts(void)
     90{
     91	int err, duration = 0;
     92	struct bprm_opts *skel = NULL;
     93
     94	skel = bprm_opts__open_and_load();
     95	if (CHECK(!skel, "skel_load", "skeleton failed\n"))
     96		goto close_prog;
     97
     98	err = bprm_opts__attach(skel);
     99	if (CHECK(err, "attach", "attach failed: %d\n", err))
    100		goto close_prog;
    101
    102	/* Run the test with the secureexec bit unset */
    103	err = run_set_secureexec(bpf_map__fd(skel->maps.secure_exec_task_map),
    104				 0 /* secureexec */);
    105	if (CHECK(err, "run_set_secureexec:0", "err = %d\n", err))
    106		goto close_prog;
    107
    108	/* Run the test with the secureexec bit set */
    109	err = run_set_secureexec(bpf_map__fd(skel->maps.secure_exec_task_map),
    110				 1 /* secureexec */);
    111	if (CHECK(err, "run_set_secureexec:1", "err = %d\n", err))
    112		goto close_prog;
    113
    114close_prog:
    115	bprm_opts__destroy(skel);
    116}