|
0
|
1 /* Linux host-specific hook definitions.
|
|
131
|
2 Copyright (C) 2004-2018 Free Software Foundation, Inc.
|
|
0
|
3
|
|
|
4 This file is part of GCC.
|
|
|
5
|
|
|
6 GCC is free software; you can redistribute it and/or modify it
|
|
|
7 under the terms of the GNU General Public License as published
|
|
|
8 by the Free Software Foundation; either version 3, or (at your
|
|
|
9 option) any later version.
|
|
|
10
|
|
|
11 GCC is distributed in the hope that it will be useful, but WITHOUT
|
|
|
12 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
|
|
|
13 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
|
|
|
14 License for more details.
|
|
|
15
|
|
|
16 You should have received a copy of the GNU General Public License
|
|
|
17 along with GCC; see the file COPYING3. If not see
|
|
|
18 <http://www.gnu.org/licenses/>. */
|
|
|
19
|
|
|
20 #include "config.h"
|
|
|
21 #include "system.h"
|
|
|
22 #include "coretypes.h"
|
|
|
23 #include "hosthooks.h"
|
|
|
24 #include "hosthooks-def.h"
|
|
|
25
|
|
|
26
|
|
|
27 /* Linux has a feature called exec-shield-randomize that perturbs the
|
|
|
28 address of non-fixed mapped segments by a (relatively) small amount.
|
|
|
29 The feature is intended to make it harder to attack the system with
|
|
|
30 buffer overflow attacks, since every invocation of a program will
|
|
|
31 have its libraries and data segments at slightly different addresses.
|
|
|
32
|
|
|
33 This feature causes us problems with PCH because it makes it that
|
|
|
34 much harder to acquire a stable location at which to map our PCH
|
|
|
35 data file.
|
|
|
36
|
|
|
37 [ The feature causes other points of non-determinism within the
|
|
|
38 compiler as well, so we'd *really* like to be able to have the
|
|
|
39 driver disable exec-shield-randomize for the process group, but
|
|
|
40 that isn't possible at present. ]
|
|
|
41
|
|
|
42 We're going to try several things:
|
|
|
43
|
|
|
44 * Select an architecture specific address as "likely" and see
|
|
|
45 if that's free. For our 64-bit hosts, we can easily choose
|
|
|
46 an address in Never Never Land.
|
|
|
47
|
|
|
48 * If exec-shield-randomize is disabled, then just use the
|
|
|
49 address chosen by mmap in step one.
|
|
|
50
|
|
|
51 * If exec-shield-randomize is enabled, then temporarily allocate
|
|
|
52 32M of memory as a buffer, then allocate PCH memory, then
|
|
|
53 free the buffer. The theory here is that the perturbation is
|
|
|
54 no more than 16M, and so by allocating our buffer larger than
|
|
|
55 that we make it considerably more likely that the address will
|
|
|
56 be free when we want to load the data back.
|
|
|
57 */
|
|
|
58
|
|
|
59 #undef HOST_HOOKS_GT_PCH_GET_ADDRESS
|
|
|
60 #define HOST_HOOKS_GT_PCH_GET_ADDRESS linux_gt_pch_get_address
|
|
|
61
|
|
|
62 #undef HOST_HOOKS_GT_PCH_USE_ADDRESS
|
|
|
63 #define HOST_HOOKS_GT_PCH_USE_ADDRESS linux_gt_pch_use_address
|
|
|
64
|
|
|
65 /* For various ports, try to guess a fixed spot in the vm space
|
|
|
66 that's probably free. */
|
|
|
67 #if defined(__alpha)
|
|
|
68 # define TRY_EMPTY_VM_SPACE 0x10000000000
|
|
|
69 #elif defined(__ia64)
|
|
|
70 # define TRY_EMPTY_VM_SPACE 0x2000000100000000
|
|
111
|
71 #elif defined(__x86_64) && defined(__LP64__)
|
|
|
72 # define TRY_EMPTY_VM_SPACE 0x1000000000
|
|
0
|
73 #elif defined(__x86_64)
|
|
111
|
74 # define TRY_EMPTY_VM_SPACE 0x60000000
|
|
0
|
75 #elif defined(__i386)
|
|
|
76 # define TRY_EMPTY_VM_SPACE 0x60000000
|
|
|
77 #elif defined(__powerpc__)
|
|
|
78 # define TRY_EMPTY_VM_SPACE 0x60000000
|
|
|
79 #elif defined(__s390x__)
|
|
|
80 # define TRY_EMPTY_VM_SPACE 0x8000000000
|
|
|
81 #elif defined(__s390__)
|
|
|
82 # define TRY_EMPTY_VM_SPACE 0x60000000
|
|
|
83 #elif defined(__sparc__) && defined(__LP64__)
|
|
|
84 # define TRY_EMPTY_VM_SPACE 0x8000000000
|
|
|
85 #elif defined(__sparc__)
|
|
|
86 # define TRY_EMPTY_VM_SPACE 0x60000000
|
|
|
87 #elif defined(__mc68000__)
|
|
|
88 # define TRY_EMPTY_VM_SPACE 0x40000000
|
|
111
|
89 #elif defined(__aarch64__) && defined(__ILP32__)
|
|
|
90 # define TRY_EMPTY_VM_SPACE 0x60000000
|
|
|
91 #elif defined(__aarch64__)
|
|
|
92 # define TRY_EMPTY_VM_SPACE 0x1000000000
|
|
|
93 #elif defined(__ARM_EABI__)
|
|
|
94 # define TRY_EMPTY_VM_SPACE 0x60000000
|
|
|
95 #elif defined(__mips__) && defined(__LP64__)
|
|
|
96 # define TRY_EMPTY_VM_SPACE 0x8000000000
|
|
|
97 #elif defined(__mips__)
|
|
|
98 # define TRY_EMPTY_VM_SPACE 0x60000000
|
|
0
|
99 #else
|
|
|
100 # define TRY_EMPTY_VM_SPACE 0
|
|
|
101 #endif
|
|
|
102
|
|
|
103 /* Determine a location where we might be able to reliably allocate SIZE
|
|
|
104 bytes. FD is the PCH file, though we should return with the file
|
|
|
105 unmapped. */
|
|
|
106
|
|
|
107 static void *
|
|
|
108 linux_gt_pch_get_address (size_t size, int fd)
|
|
|
109 {
|
|
|
110 size_t buffer_size = 32 * 1024 * 1024;
|
|
|
111 void *addr, *buffer;
|
|
|
112 FILE *f;
|
|
|
113 bool randomize_on;
|
|
|
114
|
|
|
115 addr = mmap ((void *)TRY_EMPTY_VM_SPACE, size, PROT_READ | PROT_WRITE,
|
|
|
116 MAP_PRIVATE, fd, 0);
|
|
|
117
|
|
|
118 /* If we failed the map, that means there's *no* free space. */
|
|
|
119 if (addr == (void *) MAP_FAILED)
|
|
|
120 return NULL;
|
|
|
121 /* Unmap the area before returning. */
|
|
|
122 munmap (addr, size);
|
|
|
123
|
|
|
124 /* If we got the exact area we requested, then that's great. */
|
|
|
125 if (TRY_EMPTY_VM_SPACE && addr == (void *) TRY_EMPTY_VM_SPACE)
|
|
|
126 return addr;
|
|
|
127
|
|
|
128 /* If we didn't, then we need to look to see if virtual address
|
|
|
129 randomization is on. That is recorded in
|
|
|
130 kernel.randomize_va_space. An older implementation used
|
|
|
131 kernel.exec-shield-randomize. */
|
|
|
132 f = fopen ("/proc/sys/kernel/randomize_va_space", "r");
|
|
|
133 if (f == NULL)
|
|
|
134 f = fopen ("/proc/sys/kernel/exec-shield-randomize", "r");
|
|
|
135 randomize_on = false;
|
|
|
136 if (f != NULL)
|
|
|
137 {
|
|
|
138 char buf[100];
|
|
|
139 size_t c;
|
|
|
140
|
|
|
141 c = fread (buf, 1, sizeof buf - 1, f);
|
|
|
142 if (c > 0)
|
|
|
143 {
|
|
|
144 buf[c] = '\0';
|
|
|
145 randomize_on = (atoi (buf) > 0);
|
|
|
146 }
|
|
|
147 fclose (f);
|
|
|
148 }
|
|
|
149
|
|
|
150 /* If it isn't, then accept the address that mmap selected as fine. */
|
|
|
151 if (!randomize_on)
|
|
|
152 return addr;
|
|
|
153
|
|
|
154 /* Otherwise, we need to try again with buffer space. */
|
|
|
155 buffer = mmap (0, buffer_size, PROT_NONE, MAP_PRIVATE | MAP_ANON, -1, 0);
|
|
|
156 addr = mmap (0, size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
|
|
|
157 if (buffer != (void *) MAP_FAILED)
|
|
|
158 munmap (buffer, buffer_size);
|
|
|
159 if (addr == (void *) MAP_FAILED)
|
|
|
160 return NULL;
|
|
|
161 munmap (addr, size);
|
|
|
162
|
|
|
163 return addr;
|
|
|
164 }
|
|
|
165
|
|
|
166 /* Map SIZE bytes of FD+OFFSET at BASE. Return 1 if we succeeded at
|
|
|
167 mapping the data at BASE, -1 if we couldn't.
|
|
|
168
|
|
|
169 It's not possibly to reliably mmap a file using MAP_PRIVATE to
|
|
|
170 a specific START address on either hpux or linux. First we see
|
|
|
171 if mmap with MAP_PRIVATE works. If it does, we are off to the
|
|
|
172 races. If it doesn't, we try an anonymous private mmap since the
|
|
|
173 kernel is more likely to honor the BASE address in anonymous maps.
|
|
|
174 We then copy the data to the anonymous private map. This assumes
|
|
|
175 of course that we don't need to change the data in the PCH file
|
|
|
176 after it is created.
|
|
|
177
|
|
|
178 This approach obviously causes a performance penalty but there is
|
|
|
179 little else we can do given the current PCH implementation. */
|
|
|
180
|
|
|
181 static int
|
|
|
182 linux_gt_pch_use_address (void *base, size_t size, int fd, size_t offset)
|
|
|
183 {
|
|
|
184 void *addr;
|
|
|
185
|
|
|
186 /* We're called with size == 0 if we're not planning to load a PCH
|
|
|
187 file at all. This allows the hook to free any static space that
|
|
|
188 we might have allocated at link time. */
|
|
|
189 if (size == 0)
|
|
|
190 return -1;
|
|
|
191
|
|
|
192 /* Try to map the file with MAP_PRIVATE. */
|
|
|
193 addr = mmap (base, size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, offset);
|
|
|
194
|
|
|
195 if (addr == base)
|
|
|
196 return 1;
|
|
|
197
|
|
|
198 if (addr != (void *) MAP_FAILED)
|
|
|
199 munmap (addr, size);
|
|
|
200
|
|
|
201 /* Try to make an anonymous private mmap at the desired location. */
|
|
|
202 addr = mmap (base, size, PROT_READ | PROT_WRITE,
|
|
|
203 MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
|
|
|
204
|
|
|
205 if (addr != base)
|
|
|
206 {
|
|
|
207 if (addr != (void *) MAP_FAILED)
|
|
|
208 munmap (addr, size);
|
|
|
209 return -1;
|
|
|
210 }
|
|
|
211
|
|
|
212 if (lseek (fd, offset, SEEK_SET) == (off_t)-1)
|
|
|
213 return -1;
|
|
|
214
|
|
|
215 while (size)
|
|
|
216 {
|
|
|
217 ssize_t nbytes;
|
|
|
218
|
|
111
|
219 nbytes = read (fd, base, MIN (size, (size_t)-1 >> 1));
|
|
0
|
220 if (nbytes <= 0)
|
|
|
221 return -1;
|
|
|
222 base = (char *) base + nbytes;
|
|
|
223 size -= nbytes;
|
|
|
224 }
|
|
|
225
|
|
|
226 return 1;
|
|
|
227 }
|
|
|
228
|
|
|
229
|
|
|
230 const struct host_hooks host_hooks = HOST_HOOKS_INITIALIZER;
|
