* Contributions after 2012-01-13 are licensed under the terms of the
* GNU GPL, version 2 or (at your option) any later version.
*/
+
#include "qemu/osdep.h"
+#include "qapi/error.h"
+#include "qemu/config-file.h"
+#include "qemu/option.h"
+#include "qemu/module.h"
+#include <sys/prctl.h>
#include <seccomp.h>
#include "sysemu/seccomp.h"
+#include <linux/seccomp.h>
/* For some architectures (notably ARM) cacheflush is not supported until
* libseccomp 2.2.3, but configure enforces that we are using a more recent
struct QemuSeccompSyscall {
int32_t num;
uint8_t set;
+ uint8_t narg;
+ const struct scmp_arg_cmp *arg_cmp;
+};
+
+const struct scmp_arg_cmp sched_setscheduler_arg[] = {
+ /* was SCMP_A1(SCMP_CMP_NE, SCHED_IDLE), but expanded due to GCC 4.x bug */
+ { .arg = 1, .op = SCMP_CMP_NE, .datum_a = SCHED_IDLE }
};
static const struct QemuSeccompSyscall blacklist[] = {
{ SCMP_SYS(setpriority), QEMU_SECCOMP_SET_RESOURCECTL },
{ SCMP_SYS(sched_setparam), QEMU_SECCOMP_SET_RESOURCECTL },
{ SCMP_SYS(sched_getparam), QEMU_SECCOMP_SET_RESOURCECTL },
- { SCMP_SYS(sched_setscheduler), QEMU_SECCOMP_SET_RESOURCECTL },
+ { SCMP_SYS(sched_setscheduler), QEMU_SECCOMP_SET_RESOURCECTL,
+ ARRAY_SIZE(sched_setscheduler_arg), sched_setscheduler_arg },
{ SCMP_SYS(sched_getscheduler), QEMU_SECCOMP_SET_RESOURCECTL },
{ SCMP_SYS(sched_setaffinity), QEMU_SECCOMP_SET_RESOURCECTL },
{ SCMP_SYS(sched_getaffinity), QEMU_SECCOMP_SET_RESOURCECTL },
{ SCMP_SYS(sched_get_priority_min), QEMU_SECCOMP_SET_RESOURCECTL },
};
+static inline __attribute__((unused)) int
+qemu_seccomp(unsigned int operation, unsigned int flags, void *args)
+{
+#ifdef __NR_seccomp
+ return syscall(__NR_seccomp, operation, flags, args);
+#else
+ errno = ENOSYS;
+ return -1;
+#endif
+}
+
+static uint32_t qemu_seccomp_get_action(int set)
+{
+ switch (set) {
+ case QEMU_SECCOMP_SET_DEFAULT:
+ case QEMU_SECCOMP_SET_OBSOLETE:
+ case QEMU_SECCOMP_SET_PRIVILEGED:
+ case QEMU_SECCOMP_SET_SPAWN: {
+#if defined(SECCOMP_GET_ACTION_AVAIL) && defined(SCMP_ACT_KILL_PROCESS) && \
+ defined(SECCOMP_RET_KILL_PROCESS)
+ static int kill_process = -1;
+ if (kill_process == -1) {
+ uint32_t action = SECCOMP_RET_KILL_PROCESS;
+
+ if (qemu_seccomp(SECCOMP_GET_ACTION_AVAIL, 0, &action) == 0) {
+ kill_process = 1;
+ }
+ kill_process = 0;
+ }
+ if (kill_process == 1) {
+ return SCMP_ACT_KILL_PROCESS;
+ }
+#endif
+ return SCMP_ACT_TRAP;
+ }
+
+ case QEMU_SECCOMP_SET_RESOURCECTL:
+ return SCMP_ACT_ERRNO(EPERM);
+
+ default:
+ g_assert_not_reached();
+ }
+}
-int seccomp_start(uint32_t seccomp_opts)
+
+static int seccomp_start(uint32_t seccomp_opts, Error **errp)
{
- int rc = 0;
+ int rc = -1;
unsigned int i = 0;
scmp_filter_ctx ctx;
ctx = seccomp_init(SCMP_ACT_ALLOW);
if (ctx == NULL) {
- rc = -1;
+ error_setg(errp, "failed to initialize seccomp context");
+ goto seccomp_return;
+ }
+
+ rc = seccomp_attr_set(ctx, SCMP_FLTATR_CTL_TSYNC, 1);
+ if (rc != 0) {
+ error_setg_errno(errp, -rc,
+ "failed to set seccomp thread synchronization");
goto seccomp_return;
}
for (i = 0; i < ARRAY_SIZE(blacklist); i++) {
+ uint32_t action;
if (!(seccomp_opts & blacklist[i].set)) {
continue;
}
- rc = seccomp_rule_add(ctx, SCMP_ACT_KILL, blacklist[i].num, 0);
+ action = qemu_seccomp_get_action(blacklist[i].set);
+ rc = seccomp_rule_add_array(ctx, action, blacklist[i].num,
+ blacklist[i].narg, blacklist[i].arg_cmp);
if (rc < 0) {
+ error_setg_errno(errp, -rc,
+ "failed to add seccomp blacklist rules");
goto seccomp_return;
}
}
rc = seccomp_load(ctx);
+ if (rc < 0) {
+ error_setg_errno(errp, -rc,
+ "failed to load seccomp syscall filter in kernel");
+ }
seccomp_return:
seccomp_release(ctx);
- return rc;
+ return rc < 0 ? -1 : 0;
}
+
+#ifdef CONFIG_SECCOMP
+int parse_sandbox(void *opaque, QemuOpts *opts, Error **errp)
+{
+ if (qemu_opt_get_bool(opts, "enable", false)) {
+ uint32_t seccomp_opts = QEMU_SECCOMP_SET_DEFAULT
+ | QEMU_SECCOMP_SET_OBSOLETE;
+ const char *value = NULL;
+
+ value = qemu_opt_get(opts, "obsolete");
+ if (value) {
+ if (g_str_equal(value, "allow")) {
+ seccomp_opts &= ~QEMU_SECCOMP_SET_OBSOLETE;
+ } else if (g_str_equal(value, "deny")) {
+ /* this is the default option, this if is here
+ * to provide a little bit of consistency for
+ * the command line */
+ } else {
+ error_setg(errp, "invalid argument for obsolete");
+ return -1;
+ }
+ }
+
+ value = qemu_opt_get(opts, "elevateprivileges");
+ if (value) {
+ if (g_str_equal(value, "deny")) {
+ seccomp_opts |= QEMU_SECCOMP_SET_PRIVILEGED;
+ } else if (g_str_equal(value, "children")) {
+ seccomp_opts |= QEMU_SECCOMP_SET_PRIVILEGED;
+
+ /* calling prctl directly because we're
+ * not sure if host has CAP_SYS_ADMIN set*/
+ if (prctl(PR_SET_NO_NEW_PRIVS, 1)) {
+ error_setg(errp, "failed to set no_new_privs aborting");
+ return -1;
+ }
+ } else if (g_str_equal(value, "allow")) {
+ /* default value */
+ } else {
+ error_setg(errp, "invalid argument for elevateprivileges");
+ return -1;
+ }
+ }
+
+ value = qemu_opt_get(opts, "spawn");
+ if (value) {
+ if (g_str_equal(value, "deny")) {
+ seccomp_opts |= QEMU_SECCOMP_SET_SPAWN;
+ } else if (g_str_equal(value, "allow")) {
+ /* default value */
+ } else {
+ error_setg(errp, "invalid argument for spawn");
+ return -1;
+ }
+ }
+
+ value = qemu_opt_get(opts, "resourcecontrol");
+ if (value) {
+ if (g_str_equal(value, "deny")) {
+ seccomp_opts |= QEMU_SECCOMP_SET_RESOURCECTL;
+ } else if (g_str_equal(value, "allow")) {
+ /* default value */
+ } else {
+ error_setg(errp, "invalid argument for resourcecontrol");
+ return -1;
+ }
+ }
+
+ if (seccomp_start(seccomp_opts, errp) < 0) {
+ return -1;
+ }
+ }
+
+ return 0;
+}
+
+static QemuOptsList qemu_sandbox_opts = {
+ .name = "sandbox",
+ .implied_opt_name = "enable",
+ .head = QTAILQ_HEAD_INITIALIZER(qemu_sandbox_opts.head),
+ .desc = {
+ {
+ .name = "enable",
+ .type = QEMU_OPT_BOOL,
+ },
+ {
+ .name = "obsolete",
+ .type = QEMU_OPT_STRING,
+ },
+ {
+ .name = "elevateprivileges",
+ .type = QEMU_OPT_STRING,
+ },
+ {
+ .name = "spawn",
+ .type = QEMU_OPT_STRING,
+ },
+ {
+ .name = "resourcecontrol",
+ .type = QEMU_OPT_STRING,
+ },
+ { /* end of list */ }
+ },
+};
+
+static void seccomp_register(void)
+{
+ bool add = false;
+
+ /* FIXME: use seccomp_api_get() >= 2 check when released */
+
+#if defined(SECCOMP_FILTER_FLAG_TSYNC)
+ int check;
+
+ /* check host TSYNC capability, it returns errno == ENOSYS if unavailable */
+ check = qemu_seccomp(SECCOMP_SET_MODE_FILTER,
+ SECCOMP_FILTER_FLAG_TSYNC, NULL);
+ if (check < 0 && errno == EFAULT) {
+ add = true;
+ }
+#endif
+
+ if (add) {
+ qemu_add_opts(&qemu_sandbox_opts);
+ }
+}
+opts_init(seccomp_register);
+#endif
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