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1// SPDX-License-Identifier: GPL-2.0-only
2
3#include "../../kselftest.h"
4#include <sys/wait.h>
5#include <signal.h>
6#include <fcntl.h>
7#include <asm-generic/unistd.h>
8#include <sys/mman.h>
9#include "shadowstack.h"
10#include "cfi_rv_test.h"
11
12static struct shadow_stack_tests shstk_tests[] = {
13 { "shstk fork test\n", shadow_stack_fork_test },
14 { "map shadow stack syscall\n", shadow_stack_map_test },
15 { "shadow stack gup tests\n", shadow_stack_gup_tests },
16 { "shadow stack signal tests\n", shadow_stack_signal_test},
17 { "memory protections of shadow stack memory\n", shadow_stack_protection_test }
18};
19
20#define RISCV_SHADOW_STACK_TESTS ARRAY_SIZE(shstk_tests)
21
22/* do not optimize shadow stack related test functions */
23#pragma GCC push_options
24#pragma GCC optimize("O0")
25
26void zar(void)
27{
28 unsigned long ssp = 0;
29
30 ssp = csr_read(CSR_SSP);
31 ksft_print_msg("Spewing out shadow stack ptr: %lx\n"
32 " This is to ensure shadow stack is indeed enabled and working\n",
33 ssp);
34}
35
36void bar(void)
37{
38 zar();
39}
40
41void foo(void)
42{
43 bar();
44}
45
46void zar_child(void)
47{
48 unsigned long ssp = 0;
49
50 ssp = csr_read(CSR_SSP);
51 ksft_print_msg("Spewing out shadow stack ptr: %lx\n"
52 " This is to ensure shadow stack is indeed enabled and working\n",
53 ssp);
54}
55
56void bar_child(void)
57{
58 zar_child();
59}
60
61void foo_child(void)
62{
63 bar_child();
64}
65
66typedef void (call_func_ptr)(void);
67/*
68 * call couple of functions to test push/pop.
69 */
70int shadow_stack_call_tests(call_func_ptr fn_ptr, bool parent)
71{
72 ksft_print_msg("dummy calls for sspush and sspopchk in context of %s\n",
73 parent ? "parent" : "child");
74
75 (fn_ptr)();
76
77 return 0;
78}
79
80/* forks a thread, and ensure shadow stacks fork out */
81bool shadow_stack_fork_test(unsigned long test_num, void *ctx)
82{
83 int pid = 0, child_status = 0, parent_pid = 0, ret = 0;
84 unsigned long ss_status = 0;
85
86 ksft_print_msg("Exercising shadow stack fork test\n");
87
88 ret = my_syscall5(__NR_prctl, PR_GET_SHADOW_STACK_STATUS, &ss_status, 0, 0, 0);
89 if (ret) {
90 ksft_exit_skip("Shadow stack get status prctl failed with errorcode %d\n", ret);
91 return false;
92 }
93
94 if (!(ss_status & PR_SHADOW_STACK_ENABLE))
95 ksft_exit_skip("Shadow stack is not enabled, should be enabled via glibc\n");
96
97 parent_pid = getpid();
98 pid = fork();
99
100 if (pid) {
101 ksft_print_msg("Parent pid %d and child pid %d\n", parent_pid, pid);
102 shadow_stack_call_tests(&foo, true);
103 } else {
104 shadow_stack_call_tests(&foo_child, false);
105 }
106
107 if (pid) {
108 ksft_print_msg("Waiting on child to finish\n");
109 wait(&child_status);
110 } else {
111 /* exit child gracefully */
112 exit(0);
113 }
114
115 if (pid && WIFSIGNALED(child_status)) {
116 ksft_print_msg("Child faulted, fork test failed\n");
117 return false;
118 }
119
120 return true;
121}
122
123/* exercise 'map_shadow_stack', pivot to it and call some functions to ensure it works */
124#define SHADOW_STACK_ALLOC_SIZE 4096
125bool shadow_stack_map_test(unsigned long test_num, void *ctx)
126{
127 unsigned long shdw_addr;
128 int ret = 0;
129
130 ksft_print_msg("Exercising shadow stack map test\n");
131
132 shdw_addr = my_syscall3(__NR_map_shadow_stack, NULL, SHADOW_STACK_ALLOC_SIZE, 0);
133
134 if (((long)shdw_addr) <= 0) {
135 ksft_print_msg("map_shadow_stack failed with error code %d\n",
136 (int)shdw_addr);
137 return false;
138 }
139
140 ret = munmap((void *)shdw_addr, SHADOW_STACK_ALLOC_SIZE);
141
142 if (ret) {
143 ksft_print_msg("munmap failed with error code %d\n", ret);
144 return false;
145 }
146
147 return true;
148}
149
150/*
151 * shadow stack protection tests. map a shadow stack and
152 * validate all memory protections work on it
153 */
154bool shadow_stack_protection_test(unsigned long test_num, void *ctx)
155{
156 unsigned long shdw_addr;
157 unsigned long *write_addr = NULL;
158 int ret = 0, pid = 0, child_status = 0;
159
160 ksft_print_msg("Exercising shadow stack protection test (WPT)\n");
161
162 shdw_addr = my_syscall3(__NR_map_shadow_stack, NULL, SHADOW_STACK_ALLOC_SIZE, 0);
163
164 if (((long)shdw_addr) <= 0) {
165 ksft_print_msg("map_shadow_stack failed with error code %d\n",
166 (int)shdw_addr);
167 return false;
168 }
169
170 write_addr = (unsigned long *)shdw_addr;
171 pid = fork();
172
173 /* no child was created, return false */
174 if (pid == -1)
175 return false;
176
177 /*
178 * try to perform a store from child on shadow stack memory
179 * it should result in SIGSEGV
180 */
181 if (!pid) {
182 /* below write must lead to SIGSEGV */
183 *write_addr = 0xdeadbeef;
184 } else {
185 wait(&child_status);
186 }
187
188 /* test fail, if 0xdeadbeef present on shadow stack address */
189 if (*write_addr == 0xdeadbeef) {
190 ksft_print_msg("Shadow stack WPT failed\n");
191 return false;
192 }
193
194 /* if child reached here, then fail */
195 if (!pid) {
196 ksft_print_msg("Shadow stack WPT failed: child reached unreachable state\n");
197 return false;
198 }
199
200 /* if child exited via signal handler but not for write on ss */
201 if (WIFEXITED(child_status) &&
202 WEXITSTATUS(child_status) != CHILD_EXIT_CODE_SSWRITE) {
203 ksft_print_msg("Shadow stack WPT failed: child wasn't signaled for write\n");
204 return false;
205 }
206
207 ret = munmap(write_addr, SHADOW_STACK_ALLOC_SIZE);
208 if (ret) {
209 ksft_print_msg("Shadow stack WPT failed: munmap failed, error code %d\n",
210 ret);
211 return false;
212 }
213
214 return true;
215}
216
217#define SS_MAGIC_WRITE_VAL 0xbeefdead
218
219int gup_tests(int mem_fd, unsigned long *shdw_addr)
220{
221 unsigned long val = 0;
222
223 lseek(mem_fd, (unsigned long)shdw_addr, SEEK_SET);
224 if (read(mem_fd, &val, sizeof(val)) < 0) {
225 ksft_print_msg("Reading shadow stack mem via gup failed\n");
226 return 1;
227 }
228
229 val = SS_MAGIC_WRITE_VAL;
230 lseek(mem_fd, (unsigned long)shdw_addr, SEEK_SET);
231 if (write(mem_fd, &val, sizeof(val)) < 0) {
232 ksft_print_msg("Writing shadow stack mem via gup failed\n");
233 return 1;
234 }
235
236 if (*shdw_addr != SS_MAGIC_WRITE_VAL) {
237 ksft_print_msg("GUP write to shadow stack memory failed\n");
238 return 1;
239 }
240
241 return 0;
242}
243
244bool shadow_stack_gup_tests(unsigned long test_num, void *ctx)
245{
246 unsigned long shdw_addr = 0;
247 unsigned long *write_addr = NULL;
248 int fd = 0;
249 bool ret = false;
250
251 ksft_print_msg("Exercising shadow stack gup tests\n");
252 shdw_addr = my_syscall3(__NR_map_shadow_stack, NULL, SHADOW_STACK_ALLOC_SIZE, 0);
253
254 if (((long)shdw_addr) <= 0) {
255 ksft_print_msg("map_shadow_stack failed with error code %d\n", (int)shdw_addr);
256 return false;
257 }
258
259 write_addr = (unsigned long *)shdw_addr;
260
261 fd = open("/proc/self/mem", O_RDWR);
262 if (fd == -1)
263 return false;
264
265 if (gup_tests(fd, write_addr)) {
266 ksft_print_msg("gup tests failed\n");
267 goto out;
268 }
269
270 ret = true;
271out:
272 if (shdw_addr && munmap(write_addr, SHADOW_STACK_ALLOC_SIZE)) {
273 ksft_print_msg("munmap failed with error code %d\n", ret);
274 ret = false;
275 }
276
277 return ret;
278}
279
280volatile bool break_loop;
281
282void sigusr1_handler(int signo)
283{
284 break_loop = true;
285}
286
287bool sigusr1_signal_test(void)
288{
289 struct sigaction sa = {};
290
291 sa.sa_handler = sigusr1_handler;
292 sa.sa_flags = 0;
293 sigemptyset(&sa.sa_mask);
294 if (sigaction(SIGUSR1, &sa, NULL)) {
295 ksft_print_msg("Registering signal handler for SIGUSR1 failed\n");
296 return false;
297 }
298
299 return true;
300}
301
302/*
303 * shadow stack signal test. shadow stack must be enabled.
304 * register a signal, fork another thread which is waiting
305 * on signal. Send a signal from parent to child, verify
306 * that signal was received by child. If not test fails
307 */
308bool shadow_stack_signal_test(unsigned long test_num, void *ctx)
309{
310 int pid = 0, child_status = 0, ret = 0;
311 unsigned long ss_status = 0;
312
313 ksft_print_msg("Exercising shadow stack signal test\n");
314
315 ret = my_syscall5(__NR_prctl, PR_GET_SHADOW_STACK_STATUS, &ss_status, 0, 0, 0);
316 if (ret) {
317 ksft_print_msg("Shadow stack get status prctl failed with errorcode %d\n", ret);
318 return false;
319 }
320
321 if (!(ss_status & PR_SHADOW_STACK_ENABLE))
322 ksft_print_msg("Shadow stack is not enabled, should be enabled via glibc\n");
323
324 /* this should be caught by signal handler and do an exit */
325 if (!sigusr1_signal_test()) {
326 ksft_print_msg("Registering sigusr1 handler failed\n");
327 exit(-1);
328 }
329
330 pid = fork();
331
332 if (pid == -1) {
333 ksft_print_msg("Signal test: fork failed\n");
334 goto out;
335 }
336
337 if (pid == 0) {
338 while (!break_loop)
339 sleep(1);
340
341 exit(11);
342 /* child shouldn't go beyond here */
343 }
344
345 /* send SIGUSR1 to child */
346 kill(pid, SIGUSR1);
347 wait(&child_status);
348
349out:
350
351 return (WIFEXITED(child_status) &&
352 WEXITSTATUS(child_status) == 11);
353}
354
355int execute_shadow_stack_tests(void)
356{
357 int ret = 0;
358 unsigned long test_count = 0;
359 unsigned long shstk_status = 0;
360 bool test_pass = false;
361
362 ksft_print_msg("Executing RISC-V shadow stack self tests\n");
363 ksft_set_plan(RISCV_SHADOW_STACK_TESTS);
364
365 ret = my_syscall5(__NR_prctl, PR_GET_SHADOW_STACK_STATUS, &shstk_status, 0, 0, 0);
366
367 if (ret != 0)
368 ksft_exit_fail_msg("Get shadow stack status failed with %d\n", ret);
369
370 /*
371 * If we are here that means get shadow stack status succeeded and
372 * thus shadow stack support is baked in the kernel.
373 */
374 while (test_count < RISCV_SHADOW_STACK_TESTS) {
375 test_pass = (*shstk_tests[test_count].t_func)(test_count, NULL);
376 ksft_test_result(test_pass, shstk_tests[test_count].name);
377 test_count++;
378 }
379
380 ksft_finished();
381
382 return 0;
383}
384
385#pragma GCC pop_options