strace/tests/modify_ldt.c

/*
 * Check decoding of modify_ldt syscall.
 *
 * Copyright (c) 2018 The strace developers.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "tests.h"

#include <asm/unistd.h>

#if defined __NR_modify_ldt && defined HAVE_STRUCT_USER_DESC

# include <errno.h>
# include <stdio.h>
# include <unistd.h>
# include <asm/ldt.h>

void
print_user_desc(struct user_desc *us, const char *entry_str)
{
	if (entry_str)
		printf("{entry_number=%s", entry_str);
	else
		printf("{entry_number=%u", us->entry_number);

	printf(", base_addr=%#08x"
	       ", limit=%#08x"
	       ", seg_32bit=%u"
	       ", contents=%u"
	       ", read_exec_only=%u"
	       ", limit_in_pages=%u"
	       ", seg_not_present=%u"
	       ", useable=%u"
#ifdef __x86_64__
	       ", lm=%u"
#endif
	       "}",
	       us->base_addr,
	       us->limit,
	       us->seg_32bit,
	       us->contents,
	       us->read_exec_only,
	       us->limit_in_pages,
	       us->seg_not_present,
	       us->useable
#ifdef __x86_64__
	       , us->lm
#endif
	       );
}

void
printrc(long rc)
{
#ifdef __x86_64__
	int err = -rc;

	/* Thanks, long return type of syscall(2) */
	printf("%lld", zero_extend_signed_to_ull(rc));

	if (err > 0 && err < 0x1000) {
		errno = err;
		printf(" %s (%m)", errno2name());
	}
#else
	printf("%s", sprintrc(rc));
#endif

	puts("");
}

int
main(void)
{
	static const kernel_ulong_t bogus_func =
		(kernel_ulong_t) 0xbadc0dedda7a1057ULL;
	static const kernel_ulong_t bogus_bytecount =
		(kernel_ulong_t) 0xdeadfacefa57beefULL;

	struct user_desc *us = tail_alloc(sizeof(*us));
	long rc;

	fill_memory(us, sizeof(*us));

	rc = syscall(__NR_modify_ldt, 0, 0, 0);
	printf("modify_ldt(0, NULL, 0) = ");
	printrc(rc);

	rc = syscall(__NR_modify_ldt, bogus_func, (kernel_long_t) -1,
		     bogus_bytecount);
	printf("modify_ldt(%d, %#llx, %llu) = ",
	       (int) bogus_func,
	       zero_extend_signed_to_ull((kernel_long_t) -1),
	       (unsigned long long) bogus_bytecount);
	printrc(rc);

	rc = syscall(__NR_modify_ldt, bogus_func, us + 1, 0);
	printf("modify_ldt(%d, %p, 0) = ", (int) bogus_func, us + 1);
	printrc(rc);

	rc = syscall(__NR_modify_ldt, bogus_func, us, 42);
	printf("modify_ldt(%d, %p, 42) = ", (int) bogus_func, us);
	printrc(rc);

	rc = syscall(__NR_modify_ldt, bogus_func, us + 1, sizeof(*us));
	printf("modify_ldt(%d, %p, %zu) = ",
	       (int) bogus_func, us + 1, sizeof(*us));
	printrc(rc);

	rc = syscall(__NR_modify_ldt, bogus_func, us, sizeof(*us));
	printf("modify_ldt(%d, ", (int) bogus_func);
	print_user_desc(us, NULL);
	printf(", %zu) = ", sizeof(*us));
	printrc(rc);

	fill_memory_ex(us, sizeof(*us), 0x55, 80);
	us->entry_number = -1;
	us->base_addr = 0;
	us->limit = 0;

	rc = syscall(__NR_modify_ldt, bogus_func, us, sizeof(*us));
	printf("modify_ldt(%d, ", (int) bogus_func);
	print_user_desc(us, "-1");
	printf(", %zu) = ", sizeof(*us));
	printrc(rc);

	puts("+++ exited with 0 +++");

	return 0;
}

#else

SKIP_MAIN_UNDEFINED("__NR_modify_ldt && HAVE_STRUCT_USER_DESC");

#endif