1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
|
// relro_test.cc -- test -z relro for gold
// Copyright (C) 2008-2015 Free Software Foundation, Inc.
// Written by Ian Lance Taylor <iant@google.com>.
// This file is part of gold.
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 3 of the License, or
// (at your option) any later version.
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
// MA 02110-1301, USA.
#include <cassert>
#include <csignal>
#include <cstdio>
#include <cstdlib>
#include <exception>
#include <stdint.h>
#include <unistd.h>
// This tests we were linked with a script. If we were linked with a
// script, relro currently does not work.
extern char using_script[] __attribute__ ((weak));
// This code is put into a shared library linked with -z relro.
// i1 and i2 are not relro variables.
int i1 = 1;
static int i2 = 2;
// P1 is a global relro variable.
int* const p1 __attribute__ ((aligned(64))) = &i1;
// P2 is a local relro variable.
int* const p2 __attribute__ ((aligned(64))) = &i2;
// Add a TLS variable to make sure -z relro works correctly with TLS.
__thread int i3 = 1;
// Test symbol addresses.
bool
t1()
{
if (using_script)
return true;
void* i1addr = static_cast<void*>(&i1);
void* i2addr = static_cast<void*>(&i2);
const void* p1addr = static_cast<const void*>(&p1);
const void* p2addr = static_cast<const void*>(&p2);
// The relro variables should precede the non-relro variables in the
// memory image.
assert(i1addr > p1addr);
assert(i1addr > p2addr);
assert(i2addr > p1addr);
assert(i2addr > p2addr);
// The relro variables should not be on the same page as the
// non-relro variables.
const size_t page_size = getpagesize();
uintptr_t i1page = reinterpret_cast<uintptr_t>(i1addr) & ~ (page_size - 1);
uintptr_t i2page = reinterpret_cast<uintptr_t>(i2addr) & ~ (page_size - 1);
uintptr_t p1page = reinterpret_cast<uintptr_t>(p1addr) & ~ (page_size - 1);
uintptr_t p2page = reinterpret_cast<uintptr_t>(p2addr) & ~ (page_size - 1);
assert(i1page != p1page);
assert(i1page != p2page);
assert(i2page != p1page);
assert(i2page != p2page);
assert(i3 == 1);
return true;
}
// Tell terminate handler that we are throwing from a signal handler.
static bool throwing;
// A signal handler for SIGSEGV.
extern "C"
void
sigsegv_handler(int)
{
throwing = true;
throw 0;
}
// The original terminate handler.
std::terminate_handler orig_terminate;
// Throwing an exception out of a signal handler doesn't always work
// reliably. When that happens the program will call terminate. We
// set a terminate handler to indicate that the test probably passed.
void
terminate_handler()
{
if (!throwing)
{
orig_terminate();
::exit(EXIT_FAILURE);
}
fprintf(stderr,
"relro_test: terminate called due to failure to throw through signal handler\n");
fprintf(stderr, "relro_test: assuming test succeeded\n");
::exit(EXIT_SUCCESS);
}
// Use a separate function to throw the exception, so that we don't
// need to use -fnon-call-exceptions.
void f2() __attribute__ ((noinline));
void
f2()
{
int** pp1 = const_cast<int**>(&p1);
*pp1 = &i2;
// We shouldn't get here--the assignment to *pp1 should write to
// memory which the dynamic linker marked as read-only, giving us a
// SIGSEGV, causing sigsegv_handler to be invoked, to throw past us.
assert(0);
}
// Changing a relro variable should give us a SIGSEGV.
bool
t2()
{
if (using_script)
return true;
signal(SIGSEGV, sigsegv_handler);
orig_terminate = std::set_terminate(terminate_handler);
try
{
f2();
return false;
}
catch (int i)
{
assert(i == 0);
return true;
}
}
|
