xref: /qemu/tests/unit/test-seccomp.c (revision b2a3cbb8) 
1 /*
2  * QEMU seccomp test suite
3  *
4  * Copyright (c) 2021 Red Hat, Inc.
5  *
6  * This library is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU Lesser General Public
8  * License as published by the Free Software Foundation; either
9  * version 2.1 of the License, or (at your option) any later version.
10  *
11  * This library is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
14  * Lesser General Public License for more details.
15  *
16  * You should have received a copy of the GNU Lesser General Public
17  * License along with this library; if not, see <http://www.gnu.org/licenses/>.
18  *
19  */
20 
21 #include "qemu/osdep.h"
22 #include "qemu/config-file.h"
23 #include "qemu/option.h"
24 #include "sysemu/seccomp.h"
25 #include "qapi/error.h"
26 #include "qemu/module.h"
27 
28 #include <unistd.h>
29 #include <sys/syscall.h>
30 
31 static void test_seccomp_helper(const char *args, bool killed,
32                                 int errnum, int (*doit)(void))
33 {
34     if (g_test_subprocess()) {
35         QemuOptsList *olist;
36         QemuOpts *opts;
37         int ret;
38 
39         module_call_init(MODULE_INIT_OPTS);
40         olist = qemu_find_opts("sandbox");
41         g_assert(olist != NULL);
42 
43         opts = qemu_opts_parse_noisily(olist, args, true);
44         g_assert(opts != NULL);
45 
46         parse_sandbox(NULL, opts, &error_abort);
47 
48         /* Running in a child process */
49         ret = doit();
50 
51         if (errnum != 0) {
52             g_assert(ret != 0);
53             g_assert(errno == errnum);
54         } else {
55             g_assert(ret == 0);
56         }
57 
58         _exit(0);
59     } else {
60         /* Running in main test process, spawning the child */
61         g_test_trap_subprocess(NULL, 0, 0);
62         if (killed) {
63             g_test_trap_assert_failed();
64         } else {
65             g_test_trap_assert_passed();
66         }
67     }
68 }
69 
70 
71 static void test_seccomp_killed(const char *args, int (*doit)(void))
72 {
73     test_seccomp_helper(args, true, 0, doit);
74 }
75 
76 static void test_seccomp_errno(const char *args, int errnum, int (*doit)(void))
77 {
78     test_seccomp_helper(args, false, errnum, doit);
79 }
80 
81 static void test_seccomp_passed(const char *args, int (*doit)(void))
82 {
83     test_seccomp_helper(args, false, 0, doit);
84 }
85 
86 #ifdef SYS_fork
87 static int doit_sys_fork(void)
88 {
89     int ret = syscall(SYS_fork);
90     if (ret < 0) {
91         return ret;
92     }
93     if (ret == 0) {
94         _exit(0);
95     }
96     return 0;
97 }
98 
99 static void test_seccomp_sys_fork_on_nospawn(void)
100 {
101     test_seccomp_killed("on,spawn=deny", doit_sys_fork);
102 }
103 
104 static void test_seccomp_sys_fork_on(void)
105 {
106     test_seccomp_passed("on", doit_sys_fork);
107 }
108 
109 static void test_seccomp_sys_fork_off(void)
110 {
111     test_seccomp_passed("off", doit_sys_fork);
112 }
113 #endif
114 
115 static int doit_fork(void)
116 {
117     int ret = fork();
118     if (ret < 0) {
119         return ret;
120     }
121     if (ret == 0) {
122         _exit(0);
123     }
124     return 0;
125 }
126 
127 static void test_seccomp_fork_on_nospawn(void)
128 {
129     test_seccomp_killed("on,spawn=deny", doit_fork);
130 }
131 
132 static void test_seccomp_fork_on(void)
133 {
134     test_seccomp_passed("on", doit_fork);
135 }
136 
137 static void test_seccomp_fork_off(void)
138 {
139     test_seccomp_passed("off", doit_fork);
140 }
141 
142 static void *noop(void *arg)
143 {
144     return arg;
145 }
146 
147 static int doit_thread(void)
148 {
149     pthread_t th;
150     int ret = pthread_create(&th, NULL, noop, NULL);
151     if (ret != 0) {
152         errno = ret;
153         return -1;
154     } else {
155         pthread_join(th, NULL);
156         return 0;
157     }
158 }
159 
160 static void test_seccomp_thread_on(void)
161 {
162     test_seccomp_passed("on", doit_thread);
163 }
164 
165 static void test_seccomp_thread_on_nospawn(void)
166 {
167     test_seccomp_passed("on,spawn=deny", doit_thread);
168 }
169 
170 static void test_seccomp_thread_off(void)
171 {
172     test_seccomp_passed("off", doit_thread);
173 }
174 
175 static int doit_sched(void)
176 {
177     struct sched_param param = { .sched_priority = 0 };
178     return sched_setscheduler(getpid(), SCHED_OTHER, &param);
179 }
180 
181 static void test_seccomp_sched_on_nores(void)
182 {
183     test_seccomp_errno("on,resourcecontrol=deny", EPERM, doit_sched);
184 }
185 
186 static void test_seccomp_sched_on(void)
187 {
188     test_seccomp_passed("on", doit_sched);
189 }
190 
191 static void test_seccomp_sched_off(void)
192 {
193     test_seccomp_passed("off", doit_sched);
194 }
195 
196 static bool can_play_with_seccomp(void)
197 {
198     g_autofree char *status = NULL;
199     g_auto(GStrv) lines = NULL;
200     size_t i;
201 
202     if (!g_file_get_contents("/proc/self/status", &status, NULL, NULL)) {
203         return false;
204     }
205 
206     lines = g_strsplit(status, "\n", 0);
207 
208     for (i = 0; lines[i] != NULL; i++) {
209         if (g_str_has_prefix(lines[i], "Seccomp:")) {
210             /*
211              * "Seccomp: 1" or "Seccomp: 2" indicate we're already
212              * confined, probably as we're inside a container. In
213              * this case our tests might get unexpected results,
214              * so we can't run reliably
215              */
216             if (!strchr(lines[i], '0')) {
217                 return false;
218             }
219 
220             return true;
221         }
222     }
223 
224     /* Doesn't look like seccomp is enabled in the kernel */
225     return false;
226 }
227 
228 int main(int argc, char **argv)
229 {
230     g_test_init(&argc, &argv, NULL);
231     if (can_play_with_seccomp()) {
232 #ifdef SYS_fork
233         g_test_add_func("/softmmu/seccomp/sys-fork/on",
234                         test_seccomp_sys_fork_on);
235         g_test_add_func("/softmmu/seccomp/sys-fork/on-nospawn",
236                         test_seccomp_sys_fork_on_nospawn);
237         g_test_add_func("/softmmu/seccomp/sys-fork/off",
238                         test_seccomp_sys_fork_off);
239 #endif
240 
241         g_test_add_func("/softmmu/seccomp/fork/on",
242                         test_seccomp_fork_on);
243         g_test_add_func("/softmmu/seccomp/fork/on-nospawn",
244                         test_seccomp_fork_on_nospawn);
245         g_test_add_func("/softmmu/seccomp/fork/off",
246                         test_seccomp_fork_off);
247 
248         g_test_add_func("/softmmu/seccomp/thread/on",
249                         test_seccomp_thread_on);
250         g_test_add_func("/softmmu/seccomp/thread/on-nospawn",
251                         test_seccomp_thread_on_nospawn);
252         g_test_add_func("/softmmu/seccomp/thread/off",
253                         test_seccomp_thread_off);
254 
255         if (doit_sched() == 0) {
256             /*
257              * musl doesn't impl sched_setscheduler, hence
258              * we check above if it works first
259              */
260             g_test_add_func("/softmmu/seccomp/sched/on",
261                             test_seccomp_sched_on);
262             g_test_add_func("/softmmu/seccomp/sched/on-nores",
263                             test_seccomp_sched_on_nores);
264             g_test_add_func("/softmmu/seccomp/sched/off",
265                             test_seccomp_sched_off);
266         }
267     }
268     return g_test_run();
269 }
270