// SPDX-License-Identifier: GPL-2.0/* * Test the static transparent flag 'T' of binfmt_misc. A magic-matched * binary is dispatched to an interpreter with the argument vector left * untouched, the binary passed through AT_EXECFD and mm->exe_file labeled * with the binary. The asserting interpreter (binfmt_transparent_interp) * verifies the constructed identity from inside the process and exits 0. * * Needs root for the registration; no bpf toolchain involved. */#define _GNU_SOURCE#include <stdio.h>#include <stdlib.h> #include "binfmt_misc_common.h"#include "kselftest_harness.h" #define MAGIC		"#TRANSPARENT-SELFTEST#"#define TARGET_PATH	"/tmp/binfmt_transparent_target"#define INTERP_PATH	"/tmp/binfmt_transparent_interp"#define ENTRY		"test_transparent"#define RULE(flags)	":" ENTRY ":M:0:" MAGIC "::" INTERP_PATH ":" flags /* The target only has to carry the magic; it is never actually loaded. */static int create_target(void){	char buf[128] = MAGIC "\n";	int fd; 	unlink(TARGET_PATH);	fd = open(TARGET_PATH, O_WRONLY | O_CREAT | O_EXCL, 0755);	if (fd < 0)		return -1;	if (write(fd, buf, sizeof(buf)) != (ssize_t)sizeof(buf)) {		close(fd);		return -1;	}	close(fd);	return 0;} FIXTURE(transparent) {}; FIXTURE_SETUP(transparent){	char src[PATH_MAX]; 	if (getuid() != 0)		SKIP(return, "test must be run as root");	if (!binfmt_misc_available())		SKIP(return, "no binfmt_misc"); 	ASSERT_EQ(artifact_path(src, sizeof(src), "binfmt_transparent_interp"), 0);	ASSERT_EQ(copy_file(src, INTERP_PATH), 0);	ASSERT_EQ(create_target(), 0); 	/* Skip the whole suite on a kernel that does not know 'T'. */	if (!binfmt_flag_supported('T')) {		ASSERT_EQ(errno, EINVAL);		SKIP(return, "kernel without the 'T' flag");	}} FIXTURE_TEARDOWN(transparent){	unregister(ENTRY);	unlink(TARGET_PATH);	unlink(INTERP_PATH);} /* Grammar sanity check: the same entry without 'T' has to register. */TEST_F(transparent, plain_entry_registers){	ASSERT_EQ(write_reg(RULE("")), 0);} /* 'T' preserves the whole argv, so combining it with 'P' is rejected. */TEST_F(transparent, rejects_preserve_argv0){	ASSERT_NE(write_reg(RULE("TP")), 0);	EXPECT_EQ(errno, EINVAL);} /* The interpreter asserts the identity the kernel built for it. */TEST_F(transparent, dispatch){	ASSERT_EQ(write_reg(RULE("T")), 0); 	setenv("BINFMT_TEST_BINARY", TARGET_PATH, 1);	setenv("BINFMT_TEST_ARGV0", PAYLOAD_ARGV0, 1);	EXPECT_EQ(run_payload(TARGET_PATH), 0);} TEST_HARNESS_MAIN