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1 | // relro_test.cc -- test -z relro for gold |
2 | ||
3 | // Copyright 2008 Free Software Foundation, Inc. | |
4 | // Written by Ian Lance Taylor <iant@google.com>. | |
5 | ||
6 | // This file is part of gold. | |
7 | ||
8 | // This program is free software; you can redistribute it and/or modify | |
9 | // it under the terms of the GNU General Public License as published by | |
10 | // the Free Software Foundation; either version 3 of the License, or | |
11 | // (at your option) any later version. | |
12 | ||
13 | // This program is distributed in the hope that it will be useful, | |
14 | // but WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
16 | // GNU General Public License for more details. | |
17 | ||
18 | // You should have received a copy of the GNU General Public License | |
19 | // along with this program; if not, write to the Free Software | |
20 | // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, | |
21 | // MA 02110-1301, USA. | |
22 | ||
23 | #include <cassert> | |
24 | #include <csignal> | |
7b308235 ILT |
25 | #include <cstdio> |
26 | #include <cstdlib> | |
27 | #include <exception> | |
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28 | #include <stdint.h> |
29 | #include <unistd.h> | |
30 | ||
31 | // This code is put into a shared library linked with -z relro. | |
32 | ||
33 | // i1 and i2 are not relro variables. | |
34 | int i1 = 1; | |
35 | static int i2 = 2; | |
36 | ||
37 | // P1 is a global relro variable. | |
38 | int* const p1 = &i1; | |
39 | ||
40 | // P2 is a local relro variable. | |
41 | int* const p2 = &i2; | |
42 | ||
43 | // Test symbol addresses. | |
44 | ||
45 | bool | |
46 | t1() | |
47 | { | |
48 | void* i1addr = static_cast<void*>(&i1); | |
49 | void* i2addr = static_cast<void*>(&i2); | |
50 | const void* p1addr = static_cast<const void*>(&p1); | |
51 | const void* p2addr = static_cast<const void*>(&p2); | |
52 | ||
53 | // The relro variables should precede the non-relro variables in the | |
54 | // memory image. | |
55 | assert(i1addr > p1addr); | |
56 | assert(i1addr > p2addr); | |
57 | assert(i2addr > p1addr); | |
58 | assert(i2addr > p2addr); | |
59 | ||
60 | // The relro variables should not be on the same page as the | |
61 | // non-relro variables. | |
62 | const size_t page_size = getpagesize(); | |
63 | uintptr_t i1page = reinterpret_cast<uintptr_t>(i1addr) & ~ (page_size - 1); | |
64 | uintptr_t i2page = reinterpret_cast<uintptr_t>(i2addr) & ~ (page_size - 1); | |
65 | uintptr_t p1page = reinterpret_cast<uintptr_t>(p1addr) & ~ (page_size - 1); | |
66 | uintptr_t p2page = reinterpret_cast<uintptr_t>(p2addr) & ~ (page_size - 1); | |
67 | assert(i1page != p1page); | |
68 | assert(i1page != p2page); | |
69 | assert(i2page != p1page); | |
70 | assert(i2page != p2page); | |
71 | ||
72 | return true; | |
73 | } | |
74 | ||
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75 | // Tell terminate handler that we are throwing from a signal handler. |
76 | ||
77 | static bool throwing; | |
78 | ||
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79 | // A signal handler for SIGSEGV. |
80 | ||
81 | extern "C" | |
82 | void | |
83 | sigsegv_handler(int) | |
84 | { | |
7b308235 | 85 | throwing = true; |
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86 | throw 0; |
87 | } | |
88 | ||
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89 | // The original terminate handler. |
90 | ||
91 | std::terminate_handler orig_terminate; | |
92 | ||
93 | // Throwing an exception out of a signal handler doesn't always work | |
94 | // reliably. When that happens the program will call terminate. We | |
95 | // set a terminate handler to indicate that the test probably passed. | |
96 | ||
97 | void | |
98 | terminate_handler() | |
99 | { | |
100 | if (!throwing) | |
101 | { | |
102 | orig_terminate(); | |
103 | ::exit(EXIT_FAILURE); | |
104 | } | |
105 | fprintf(stderr, | |
106 | "relro_test: terminate called due to failure to throw through signal handler\n"); | |
107 | fprintf(stderr, "relro_test: assuming test succeeded\n"); | |
108 | ::exit(EXIT_SUCCESS); | |
109 | } | |
110 | ||
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111 | // Use a separate function to throw the exception, so that we don't |
112 | // need to use -fnon-call-exceptions. | |
113 | ||
114 | void f2() __attribute__ ((noinline)); | |
115 | void | |
116 | f2() | |
117 | { | |
118 | int** pp1 = const_cast<int**>(&p1); | |
119 | *pp1 = &i2; | |
120 | ||
121 | // We shouldn't get here--the assignment to *pp1 should write to | |
122 | // memory which the dynamic linker marked as read-only, giving us a | |
123 | // SIGSEGV, causing sigsegv_handler to be invoked, to throw past us. | |
124 | assert(0); | |
125 | } | |
126 | ||
127 | // Changing a relro variable should give us a SIGSEGV. | |
128 | ||
129 | bool | |
130 | t2() | |
131 | { | |
132 | signal(SIGSEGV, sigsegv_handler); | |
7b308235 | 133 | orig_terminate = std::set_terminate(terminate_handler); |
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134 | |
135 | try | |
136 | { | |
137 | f2(); | |
138 | return false; | |
139 | } | |
140 | catch (int i) | |
141 | { | |
142 | assert(i == 0); | |
143 | return true; | |
144 | } | |
145 | } |