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
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
|
// SPDX-License-Identifier: GPL-2.0+
/*
* Ptrace test for Memory Protection Key registers
*
* Copyright (C) 2015 Anshuman Khandual, IBM Corporation.
* Copyright (C) 2018 IBM Corporation.
*/
#include "ptrace.h"
#include "child.h"
#ifndef __NR_pkey_alloc
#define __NR_pkey_alloc 384
#endif
#ifndef __NR_pkey_free
#define __NR_pkey_free 385
#endif
#ifndef NT_PPC_PKEY
#define NT_PPC_PKEY 0x110
#endif
#ifndef PKEY_DISABLE_EXECUTE
#define PKEY_DISABLE_EXECUTE 0x4
#endif
#define AMR_BITS_PER_PKEY 2
#define PKEY_REG_BITS (sizeof(u64) * 8)
#define pkeyshift(pkey) (PKEY_REG_BITS - ((pkey + 1) * AMR_BITS_PER_PKEY))
static const char user_read[] = "[User Read (Running)]";
static const char user_write[] = "[User Write (Running)]";
static const char ptrace_read_running[] = "[Ptrace Read (Running)]";
static const char ptrace_write_running[] = "[Ptrace Write (Running)]";
/* Information shared between the parent and the child. */
struct shared_info {
struct child_sync child_sync;
/* AMR value the parent expects to read from the child. */
unsigned long amr1;
/* AMR value the parent is expected to write to the child. */
unsigned long amr2;
/* AMR value that ptrace should refuse to write to the child. */
unsigned long amr3;
/* IAMR value the parent expects to read from the child. */
unsigned long expected_iamr;
/* UAMOR value the parent expects to read from the child. */
unsigned long expected_uamor;
/*
* IAMR and UAMOR values that ptrace should refuse to write to the child
* (even though they're valid ones) because userspace doesn't have
* access to those registers.
*/
unsigned long new_iamr;
unsigned long new_uamor;
};
static int sys_pkey_alloc(unsigned long flags, unsigned long init_access_rights)
{
return syscall(__NR_pkey_alloc, flags, init_access_rights);
}
static int sys_pkey_free(int pkey)
{
return syscall(__NR_pkey_free, pkey);
}
static int child(struct shared_info *info)
{
unsigned long reg;
bool disable_execute = true;
int pkey1, pkey2, pkey3;
int ret;
/* Wait until parent fills out the initial register values. */
ret = wait_parent(&info->child_sync);
if (ret)
return ret;
/* Get some pkeys so that we can change their bits in the AMR. */
pkey1 = sys_pkey_alloc(0, PKEY_DISABLE_EXECUTE);
if (pkey1 < 0) {
pkey1 = sys_pkey_alloc(0, 0);
CHILD_FAIL_IF(pkey1 < 0, &info->child_sync);
disable_execute = false;
}
pkey2 = sys_pkey_alloc(0, 0);
CHILD_FAIL_IF(pkey2 < 0, &info->child_sync);
pkey3 = sys_pkey_alloc(0, 0);
CHILD_FAIL_IF(pkey3 < 0, &info->child_sync);
info->amr1 |= 3ul << pkeyshift(pkey1);
info->amr2 |= 3ul << pkeyshift(pkey2);
info->amr3 |= info->amr2 | 3ul << pkeyshift(pkey3);
if (disable_execute)
info->expected_iamr |= 1ul << pkeyshift(pkey1);
else
info->expected_iamr &= ~(1ul << pkeyshift(pkey1));
info->expected_iamr &= ~(1ul << pkeyshift(pkey2) | 1ul << pkeyshift(pkey3));
info->expected_uamor |= 3ul << pkeyshift(pkey1) |
3ul << pkeyshift(pkey2);
info->new_iamr |= 1ul << pkeyshift(pkey1) | 1ul << pkeyshift(pkey2);
info->new_uamor |= 3ul << pkeyshift(pkey1);
/*
* We won't use pkey3. We just want a plausible but invalid key to test
* whether ptrace will let us write to AMR bits we are not supposed to.
*
* This also tests whether the kernel restores the UAMOR permissions
* after a key is freed.
*/
sys_pkey_free(pkey3);
printf("%-30s AMR: %016lx pkey1: %d pkey2: %d pkey3: %d\n",
user_write, info->amr1, pkey1, pkey2, pkey3);
mtspr(SPRN_AMR, info->amr1);
/* Wait for parent to read our AMR value and write a new one. */
ret = prod_parent(&info->child_sync);
CHILD_FAIL_IF(ret, &info->child_sync);
ret = wait_parent(&info->child_sync);
if (ret)
return ret;
reg = mfspr(SPRN_AMR);
printf("%-30s AMR: %016lx\n", user_read, reg);
CHILD_FAIL_IF(reg != info->amr2, &info->child_sync);
/*
* Wait for parent to try to write an invalid AMR value.
*/
ret = prod_parent(&info->child_sync);
CHILD_FAIL_IF(ret, &info->child_sync);
ret = wait_parent(&info->child_sync);
if (ret)
return ret;
reg = mfspr(SPRN_AMR);
printf("%-30s AMR: %016lx\n", user_read, reg);
CHILD_FAIL_IF(reg != info->amr2, &info->child_sync);
/*
* Wait for parent to try to write an IAMR and a UAMOR value. We can't
* verify them, but we can verify that the AMR didn't change.
*/
ret = prod_parent(&info->child_sync);
CHILD_FAIL_IF(ret, &info->child_sync);
ret = wait_parent(&info->child_sync);
if (ret)
return ret;
reg = mfspr(SPRN_AMR);
printf("%-30s AMR: %016lx\n", user_read, reg);
CHILD_FAIL_IF(reg != info->amr2, &info->child_sync);
/* Now let parent now that we are finished. */
ret = prod_parent(&info->child_sync);
CHILD_FAIL_IF(ret, &info->child_sync);
return TEST_PASS;
}
static int parent(struct shared_info *info, pid_t pid)
{
unsigned long regs[3];
int ret, status;
/*
* Get the initial values for AMR, IAMR and UAMOR and communicate them
* to the child.
*/
ret = ptrace_read_regs(pid, NT_PPC_PKEY, regs, 3);
PARENT_SKIP_IF_UNSUPPORTED(ret, &info->child_sync);
PARENT_FAIL_IF(ret, &info->child_sync);
info->amr1 = info->amr2 = info->amr3 = regs[0];
info->expected_iamr = info->new_iamr = regs[1];
info->expected_uamor = info->new_uamor = regs[2];
/* Wake up child so that it can set itself up. */
ret = prod_child(&info->child_sync);
PARENT_FAIL_IF(ret, &info->child_sync);
ret = wait_child(&info->child_sync);
if (ret)
return ret;
/* Verify that we can read the pkey registers from the child. */
ret = ptrace_read_regs(pid, NT_PPC_PKEY, regs, 3);
PARENT_FAIL_IF(ret, &info->child_sync);
printf("%-30s AMR: %016lx IAMR: %016lx UAMOR: %016lx\n",
ptrace_read_running, regs[0], regs[1], regs[2]);
PARENT_FAIL_IF(regs[0] != info->amr1, &info->child_sync);
PARENT_FAIL_IF(regs[1] != info->expected_iamr, &info->child_sync);
PARENT_FAIL_IF(regs[2] != info->expected_uamor, &info->child_sync);
/* Write valid AMR value in child. */
ret = ptrace_write_regs(pid, NT_PPC_PKEY, &info->amr2, 1);
PARENT_FAIL_IF(ret, &info->child_sync);
printf("%-30s AMR: %016lx\n", ptrace_write_running, info->amr2);
/* Wake up child so that it can verify it changed. */
ret = prod_child(&info->child_sync);
PARENT_FAIL_IF(ret, &info->child_sync);
ret = wait_child(&info->child_sync);
if (ret)
return ret;
/* Write invalid AMR value in child. */
ret = ptrace_write_regs(pid, NT_PPC_PKEY, &info->amr3, 1);
PARENT_FAIL_IF(ret, &info->child_sync);
printf("%-30s AMR: %016lx\n", ptrace_write_running, info->amr3);
/* Wake up child so that it can verify it didn't change. */
ret = prod_child(&info->child_sync);
PARENT_FAIL_IF(ret, &info->child_sync);
ret = wait_child(&info->child_sync);
if (ret)
return ret;
/* Try to write to IAMR. */
regs[0] = info->amr1;
regs[1] = info->new_iamr;
ret = ptrace_write_regs(pid, NT_PPC_PKEY, regs, 2);
PARENT_FAIL_IF(!ret, &info->child_sync);
printf("%-30s AMR: %016lx IAMR: %016lx\n",
ptrace_write_running, regs[0], regs[1]);
/* Try to write to IAMR and UAMOR. */
regs[2] = info->new_uamor;
ret = ptrace_write_regs(pid, NT_PPC_PKEY, regs, 3);
PARENT_FAIL_IF(!ret, &info->child_sync);
printf("%-30s AMR: %016lx IAMR: %016lx UAMOR: %016lx\n",
ptrace_write_running, regs[0], regs[1], regs[2]);
/* Verify that all registers still have their expected values. */
ret = ptrace_read_regs(pid, NT_PPC_PKEY, regs, 3);
PARENT_FAIL_IF(ret, &info->child_sync);
printf("%-30s AMR: %016lx IAMR: %016lx UAMOR: %016lx\n",
ptrace_read_running, regs[0], regs[1], regs[2]);
PARENT_FAIL_IF(regs[0] != info->amr2, &info->child_sync);
PARENT_FAIL_IF(regs[1] != info->expected_iamr, &info->child_sync);
PARENT_FAIL_IF(regs[2] != info->expected_uamor, &info->child_sync);
/* Wake up child so that it can verify AMR didn't change and wrap up. */
ret = prod_child(&info->child_sync);
PARENT_FAIL_IF(ret, &info->child_sync);
ret = wait(&status);
if (ret != pid) {
printf("Child's exit status not captured\n");
ret = TEST_PASS;
} else if (!WIFEXITED(status)) {
printf("Child exited abnormally\n");
ret = TEST_FAIL;
} else
ret = WEXITSTATUS(status) ? TEST_FAIL : TEST_PASS;
return ret;
}
static int ptrace_pkey(void)
{
struct shared_info *info;
int shm_id;
int ret;
pid_t pid;
shm_id = shmget(IPC_PRIVATE, sizeof(*info), 0777 | IPC_CREAT);
info = shmat(shm_id, NULL, 0);
ret = init_child_sync(&info->child_sync);
if (ret)
return ret;
pid = fork();
if (pid < 0) {
perror("fork() failed");
ret = TEST_FAIL;
} else if (pid == 0)
ret = child(info);
else
ret = parent(info, pid);
shmdt(info);
if (pid) {
destroy_child_sync(&info->child_sync);
shmctl(shm_id, IPC_RMID, NULL);
}
return ret;
}
int main(int argc, char *argv[])
{
return test_harness(ptrace_pkey, "ptrace_pkey");
}
|
