1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Copyright IBM Corporation, 2021
4 *
5 * Author: Mike Rapoport <rppt@linux.ibm.com>
6 */
7
8 #define _GNU_SOURCE
9 #include <sys/uio.h>
10 #include <sys/mman.h>
11 #include <sys/wait.h>
12 #include <sys/types.h>
13 #include <sys/ptrace.h>
14 #include <sys/syscall.h>
15 #include <sys/resource.h>
16 #include <sys/capability.h>
17
18 #include <stdlib.h>
19 #include <string.h>
20 #include <unistd.h>
21 #include <errno.h>
22 #include <stdio.h>
23
24 #include "../kselftest.h"
25
26 #define fail(fmt, ...) ksft_test_result_fail(fmt, ##__VA_ARGS__)
27 #define pass(fmt, ...) ksft_test_result_pass(fmt, ##__VA_ARGS__)
28 #define skip(fmt, ...) ksft_test_result_skip(fmt, ##__VA_ARGS__)
29
30 #ifdef __NR_memfd_secret
31
32 #define PATTERN 0x55
33
34 static const int prot = PROT_READ | PROT_WRITE;
35 static const int mode = MAP_SHARED;
36
37 static unsigned long page_size;
38 static unsigned long mlock_limit_cur;
39 static unsigned long mlock_limit_max;
40
memfd_secret(unsigned int flags)41 static int memfd_secret(unsigned int flags)
42 {
43 return syscall(__NR_memfd_secret, flags);
44 }
45
test_file_apis(int fd)46 static void test_file_apis(int fd)
47 {
48 char buf[64];
49
50 if ((read(fd, buf, sizeof(buf)) >= 0) ||
51 (write(fd, buf, sizeof(buf)) >= 0) ||
52 (pread(fd, buf, sizeof(buf), 0) >= 0) ||
53 (pwrite(fd, buf, sizeof(buf), 0) >= 0))
54 fail("unexpected file IO\n");
55 else
56 pass("file IO is blocked as expected\n");
57 }
58
test_mlock_limit(int fd)59 static void test_mlock_limit(int fd)
60 {
61 size_t len;
62 char *mem;
63
64 len = mlock_limit_cur;
65 if (len % page_size != 0)
66 len = (len/page_size) * page_size;
67
68 mem = mmap(NULL, len, prot, mode, fd, 0);
69 if (mem == MAP_FAILED) {
70 fail("unable to mmap secret memory\n");
71 return;
72 }
73 munmap(mem, len);
74
75 len = mlock_limit_max * 2;
76 mem = mmap(NULL, len, prot, mode, fd, 0);
77 if (mem != MAP_FAILED) {
78 fail("unexpected mlock limit violation\n");
79 munmap(mem, len);
80 return;
81 }
82
83 pass("mlock limit is respected\n");
84 }
85
try_process_vm_read(int fd,int pipefd[2])86 static void try_process_vm_read(int fd, int pipefd[2])
87 {
88 struct iovec liov, riov;
89 char buf[64];
90 char *mem;
91
92 if (read(pipefd[0], &mem, sizeof(mem)) < 0) {
93 fail("pipe write: %s\n", strerror(errno));
94 exit(KSFT_FAIL);
95 }
96
97 liov.iov_len = riov.iov_len = sizeof(buf);
98 liov.iov_base = buf;
99 riov.iov_base = mem;
100
101 if (process_vm_readv(getppid(), &liov, 1, &riov, 1, 0) < 0) {
102 if (errno == ENOSYS)
103 exit(KSFT_SKIP);
104 exit(KSFT_PASS);
105 }
106
107 exit(KSFT_FAIL);
108 }
109
try_ptrace(int fd,int pipefd[2])110 static void try_ptrace(int fd, int pipefd[2])
111 {
112 pid_t ppid = getppid();
113 int status;
114 char *mem;
115 long ret;
116
117 if (read(pipefd[0], &mem, sizeof(mem)) < 0) {
118 perror("pipe write");
119 exit(KSFT_FAIL);
120 }
121
122 ret = ptrace(PTRACE_ATTACH, ppid, 0, 0);
123 if (ret) {
124 perror("ptrace_attach");
125 exit(KSFT_FAIL);
126 }
127
128 ret = waitpid(ppid, &status, WUNTRACED);
129 if ((ret != ppid) || !(WIFSTOPPED(status))) {
130 fprintf(stderr, "weird waitppid result %ld stat %x\n",
131 ret, status);
132 exit(KSFT_FAIL);
133 }
134
135 if (ptrace(PTRACE_PEEKDATA, ppid, mem, 0))
136 exit(KSFT_PASS);
137
138 exit(KSFT_FAIL);
139 }
140
check_child_status(pid_t pid,const char * name)141 static void check_child_status(pid_t pid, const char *name)
142 {
143 int status;
144
145 waitpid(pid, &status, 0);
146
147 if (WIFEXITED(status) && WEXITSTATUS(status) == KSFT_SKIP) {
148 skip("%s is not supported\n", name);
149 return;
150 }
151
152 if ((WIFEXITED(status) && WEXITSTATUS(status) == KSFT_PASS) ||
153 WIFSIGNALED(status)) {
154 pass("%s is blocked as expected\n", name);
155 return;
156 }
157
158 fail("%s: unexpected memory access\n", name);
159 }
160
test_remote_access(int fd,const char * name,void (* func)(int fd,int pipefd[2]))161 static void test_remote_access(int fd, const char *name,
162 void (*func)(int fd, int pipefd[2]))
163 {
164 int pipefd[2];
165 pid_t pid;
166 char *mem;
167
168 if (pipe(pipefd)) {
169 fail("pipe failed: %s\n", strerror(errno));
170 return;
171 }
172
173 pid = fork();
174 if (pid < 0) {
175 fail("fork failed: %s\n", strerror(errno));
176 return;
177 }
178
179 if (pid == 0) {
180 func(fd, pipefd);
181 return;
182 }
183
184 mem = mmap(NULL, page_size, prot, mode, fd, 0);
185 if (mem == MAP_FAILED) {
186 fail("Unable to mmap secret memory\n");
187 return;
188 }
189
190 ftruncate(fd, page_size);
191 memset(mem, PATTERN, page_size);
192
193 if (write(pipefd[1], &mem, sizeof(mem)) < 0) {
194 fail("pipe write: %s\n", strerror(errno));
195 return;
196 }
197
198 check_child_status(pid, name);
199 }
200
test_process_vm_read(int fd)201 static void test_process_vm_read(int fd)
202 {
203 test_remote_access(fd, "process_vm_read", try_process_vm_read);
204 }
205
test_ptrace(int fd)206 static void test_ptrace(int fd)
207 {
208 test_remote_access(fd, "ptrace", try_ptrace);
209 }
210
set_cap_limits(rlim_t max)211 static int set_cap_limits(rlim_t max)
212 {
213 struct rlimit new;
214 cap_t cap = cap_init();
215
216 new.rlim_cur = max;
217 new.rlim_max = max;
218 if (setrlimit(RLIMIT_MEMLOCK, &new)) {
219 perror("setrlimit() returns error");
220 return -1;
221 }
222
223 /* drop capabilities including CAP_IPC_LOCK */
224 if (cap_set_proc(cap)) {
225 perror("cap_set_proc() returns error");
226 return -2;
227 }
228
229 return 0;
230 }
231
prepare(void)232 static void prepare(void)
233 {
234 struct rlimit rlim;
235
236 page_size = sysconf(_SC_PAGE_SIZE);
237 if (!page_size)
238 ksft_exit_fail_msg("Failed to get page size %s\n",
239 strerror(errno));
240
241 if (getrlimit(RLIMIT_MEMLOCK, &rlim))
242 ksft_exit_fail_msg("Unable to detect mlock limit: %s\n",
243 strerror(errno));
244
245 mlock_limit_cur = rlim.rlim_cur;
246 mlock_limit_max = rlim.rlim_max;
247
248 printf("page_size: %ld, mlock.soft: %ld, mlock.hard: %ld\n",
249 page_size, mlock_limit_cur, mlock_limit_max);
250
251 if (page_size > mlock_limit_cur)
252 mlock_limit_cur = page_size;
253 if (page_size > mlock_limit_max)
254 mlock_limit_max = page_size;
255
256 if (set_cap_limits(mlock_limit_max))
257 ksft_exit_fail_msg("Unable to set mlock limit: %s\n",
258 strerror(errno));
259 }
260
261 #define NUM_TESTS 4
262
main(int argc,char * argv[])263 int main(int argc, char *argv[])
264 {
265 int fd;
266
267 prepare();
268
269 ksft_print_header();
270 ksft_set_plan(NUM_TESTS);
271
272 fd = memfd_secret(0);
273 if (fd < 0) {
274 if (errno == ENOSYS)
275 ksft_exit_skip("memfd_secret is not supported\n");
276 else
277 ksft_exit_fail_msg("memfd_secret failed: %s\n",
278 strerror(errno));
279 }
280
281 test_mlock_limit(fd);
282 test_file_apis(fd);
283 test_process_vm_read(fd);
284 test_ptrace(fd);
285
286 close(fd);
287
288 ksft_finished();
289 }
290
291 #else /* __NR_memfd_secret */
292
main(int argc,char * argv[])293 int main(int argc, char *argv[])
294 {
295 printf("skip: skipping memfd_secret test (missing __NR_memfd_secret)\n");
296 return KSFT_SKIP;
297 }
298
299 #endif /* __NR_memfd_secret */
300