tests/unit/test-seccomp.c

   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     /* XXX fixme - should be killed */
 130     test_seccomp_passed("on,spawn=deny", doit_fork);
 131 }
 132
 133 static void test_seccomp_fork_on(void)
 134 {
 135     test_seccomp_passed("on", doit_fork);
 136 }
 137
 138 static void test_seccomp_fork_off(void)
 139 {
 140     test_seccomp_passed("off", doit_fork);
 141 }
 142
 143 static void *noop(void *arg)
 144 {
 145     return arg;
 146 }
 147
 148 static int doit_thread(void)
 149 {
 150     pthread_t th;
 151     int ret = pthread_create(&th, NULL, noop, NULL);
 152     if (ret != 0) {
 153         errno = ret;
 154         return -1;
 155     } else {
 156         pthread_join(th, NULL);
 157         return 0;
 158     }
 159 }
 160
 161 static void test_seccomp_thread_on(void)
 162 {
 163     test_seccomp_passed("on", doit_thread);
 164 }
 165
 166 static void test_seccomp_thread_on_nospawn(void)
 167 {
 168     test_seccomp_passed("on,spawn=deny", doit_thread);
 169 }
 170
 171 static void test_seccomp_thread_off(void)
 172 {
 173     test_seccomp_passed("off", doit_thread);
 174 }
 175
 176 static int doit_sched(void)
 177 {
 178     struct sched_param param = { .sched_priority = 0 };
 179     return sched_setscheduler(getpid(), SCHED_OTHER, &param);
 180 }
 181
 182 static void test_seccomp_sched_on_nores(void)
 183 {
 184     test_seccomp_errno("on,resourcecontrol=deny", EPERM, doit_sched);
 185 }
 186
 187 static void test_seccomp_sched_on(void)
 188 {
 189     test_seccomp_passed("on", doit_sched);
 190 }
 191
 192 static void test_seccomp_sched_off(void)
 193 {
 194     test_seccomp_passed("off", doit_sched);
 195 }
 196
 197 static bool can_play_with_seccomp(void)
 198 {
 199     g_autofree char *status = NULL;
 200     g_auto(GStrv) lines = NULL;
 201     size_t i;
 202
 203     if (!g_file_get_contents("/proc/self/status", &status, NULL, NULL)) {
 204         return false;
 205     }
 206
 207     lines = g_strsplit(status, "\n", 0);
 208
 209     for (i = 0; lines[i] != NULL; i++) {
 210         if (g_str_has_prefix(lines[i], "Seccomp:")) {
 211             /*
 212              * "Seccomp: 1" or "Seccomp: 2" indicate we're already
 213              * confined, probably as we're inside a container. In
 214              * this case our tests might get unexpected results,
 215              * so we can't run reliably
 216              */
 217             if (!strchr(lines[i], '0')) {
 218                 return false;
 219             }
 220
 221             return true;
 222         }
 223     }
 224
 225     /* Doesn't look like seccomp is enabled in the kernel */
 226     return false;
 227 }
 228
 229 int main(int argc, char **argv)
 230 {
 231     g_test_init(&argc, &argv, NULL);
 232     if (can_play_with_seccomp()) {
 233 #ifdef SYS_fork
 234         g_test_add_func("/softmmu/seccomp/sys-fork/on",
 235                         test_seccomp_sys_fork_on);
 236         g_test_add_func("/softmmu/seccomp/sys-fork/on-nospawn",
 237                         test_seccomp_sys_fork_on_nospawn);
 238         g_test_add_func("/softmmu/seccomp/sys-fork/off",
 239                         test_seccomp_sys_fork_off);
 240 #endif
 241
 242         g_test_add_func("/softmmu/seccomp/fork/on",
 243                         test_seccomp_fork_on);
 244         g_test_add_func("/softmmu/seccomp/fork/on-nospawn",
 245                         test_seccomp_fork_on_nospawn);
 246         g_test_add_func("/softmmu/seccomp/fork/off",
 247                         test_seccomp_fork_off);
 248
 249         g_test_add_func("/softmmu/seccomp/thread/on",
 250                         test_seccomp_thread_on);
 251         g_test_add_func("/softmmu/seccomp/thread/on-nospawn",
 252                         test_seccomp_thread_on_nospawn);
 253         g_test_add_func("/softmmu/seccomp/thread/off",
 254                         test_seccomp_thread_off);
 255
 256         if (doit_sched() == 0) {
 257             /*
 258              * musl doesn't impl sched_setscheduler, hence
 259              * we check above if it works first
 260              */
 261             g_test_add_func("/softmmu/seccomp/sched/on",
 262                             test_seccomp_sched_on);
 263             g_test_add_func("/softmmu/seccomp/sched/on-nores",
 264                             test_seccomp_sched_on_nores);
 265             g_test_add_func("/softmmu/seccomp/sched/off",
 266                             test_seccomp_sched_off);
 267         }
 268     }
 269     return g_test_run();
 270 }