e81e7b52f9
We'd like to compile QEMU with -std=gnu99, but GCC 4.8 currently fails to compile qemu-seccomp.c in this mode: qemu-seccomp.c:45:1: error: initializer element is not constant }; ^ qemu-seccomp.c:45:1: error: (near initialization for ‘sched_setscheduler_arg[0]’) This is due to a compiler bug which has just been fixed in GCC 5.0: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63567 Since we still want to support GCC 4.8 for a while and also want to use gnu99 mode, work-around the issue by expanding the macro manually. Reviewed-by: Daniel P. Berrangé <berrange@redhat.com> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com> Acked-by: Eduardo Otubo <otubo@redhat.com> Signed-off-by: Thomas Huth <thuth@redhat.com>
307 lines
11 KiB
C
307 lines
11 KiB
C
/*
|
|
* QEMU seccomp mode 2 support with libseccomp
|
|
*
|
|
* Copyright IBM, Corp. 2012
|
|
*
|
|
* Authors:
|
|
* Eduardo Otubo <eotubo@br.ibm.com>
|
|
*
|
|
* This work is licensed under the terms of the GNU GPL, version 2. See
|
|
* the COPYING file in the top-level directory.
|
|
*
|
|
* 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
|
|
* version on those hosts, so it is OK for this check to be less strict.
|
|
*/
|
|
#if SCMP_VER_MAJOR >= 3
|
|
#define HAVE_CACHEFLUSH
|
|
#elif SCMP_VER_MAJOR == 2 && SCMP_VER_MINOR >= 2
|
|
#define HAVE_CACHEFLUSH
|
|
#endif
|
|
|
|
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[] = {
|
|
/* default set of syscalls to blacklist */
|
|
{ SCMP_SYS(reboot), QEMU_SECCOMP_SET_DEFAULT },
|
|
{ SCMP_SYS(swapon), QEMU_SECCOMP_SET_DEFAULT },
|
|
{ SCMP_SYS(swapoff), QEMU_SECCOMP_SET_DEFAULT },
|
|
{ SCMP_SYS(syslog), QEMU_SECCOMP_SET_DEFAULT },
|
|
{ SCMP_SYS(mount), QEMU_SECCOMP_SET_DEFAULT },
|
|
{ SCMP_SYS(umount), QEMU_SECCOMP_SET_DEFAULT },
|
|
{ SCMP_SYS(kexec_load), QEMU_SECCOMP_SET_DEFAULT },
|
|
{ SCMP_SYS(afs_syscall), QEMU_SECCOMP_SET_DEFAULT },
|
|
{ SCMP_SYS(break), QEMU_SECCOMP_SET_DEFAULT },
|
|
{ SCMP_SYS(ftime), QEMU_SECCOMP_SET_DEFAULT },
|
|
{ SCMP_SYS(getpmsg), QEMU_SECCOMP_SET_DEFAULT },
|
|
{ SCMP_SYS(gtty), QEMU_SECCOMP_SET_DEFAULT },
|
|
{ SCMP_SYS(lock), QEMU_SECCOMP_SET_DEFAULT },
|
|
{ SCMP_SYS(mpx), QEMU_SECCOMP_SET_DEFAULT },
|
|
{ SCMP_SYS(prof), QEMU_SECCOMP_SET_DEFAULT },
|
|
{ SCMP_SYS(profil), QEMU_SECCOMP_SET_DEFAULT },
|
|
{ SCMP_SYS(putpmsg), QEMU_SECCOMP_SET_DEFAULT },
|
|
{ SCMP_SYS(security), QEMU_SECCOMP_SET_DEFAULT },
|
|
{ SCMP_SYS(stty), QEMU_SECCOMP_SET_DEFAULT },
|
|
{ SCMP_SYS(tuxcall), QEMU_SECCOMP_SET_DEFAULT },
|
|
{ SCMP_SYS(ulimit), QEMU_SECCOMP_SET_DEFAULT },
|
|
{ SCMP_SYS(vserver), QEMU_SECCOMP_SET_DEFAULT },
|
|
/* obsolete */
|
|
{ SCMP_SYS(readdir), QEMU_SECCOMP_SET_OBSOLETE },
|
|
{ SCMP_SYS(_sysctl), QEMU_SECCOMP_SET_OBSOLETE },
|
|
{ SCMP_SYS(bdflush), QEMU_SECCOMP_SET_OBSOLETE },
|
|
{ SCMP_SYS(create_module), QEMU_SECCOMP_SET_OBSOLETE },
|
|
{ SCMP_SYS(get_kernel_syms), QEMU_SECCOMP_SET_OBSOLETE },
|
|
{ SCMP_SYS(query_module), QEMU_SECCOMP_SET_OBSOLETE },
|
|
{ SCMP_SYS(sgetmask), QEMU_SECCOMP_SET_OBSOLETE },
|
|
{ SCMP_SYS(ssetmask), QEMU_SECCOMP_SET_OBSOLETE },
|
|
{ SCMP_SYS(sysfs), QEMU_SECCOMP_SET_OBSOLETE },
|
|
{ SCMP_SYS(uselib), QEMU_SECCOMP_SET_OBSOLETE },
|
|
{ SCMP_SYS(ustat), QEMU_SECCOMP_SET_OBSOLETE },
|
|
/* privileged */
|
|
{ SCMP_SYS(setuid), QEMU_SECCOMP_SET_PRIVILEGED },
|
|
{ SCMP_SYS(setgid), QEMU_SECCOMP_SET_PRIVILEGED },
|
|
{ SCMP_SYS(setpgid), QEMU_SECCOMP_SET_PRIVILEGED },
|
|
{ SCMP_SYS(setsid), QEMU_SECCOMP_SET_PRIVILEGED },
|
|
{ SCMP_SYS(setreuid), QEMU_SECCOMP_SET_PRIVILEGED },
|
|
{ SCMP_SYS(setregid), QEMU_SECCOMP_SET_PRIVILEGED },
|
|
{ SCMP_SYS(setresuid), QEMU_SECCOMP_SET_PRIVILEGED },
|
|
{ SCMP_SYS(setresgid), QEMU_SECCOMP_SET_PRIVILEGED },
|
|
{ SCMP_SYS(setfsuid), QEMU_SECCOMP_SET_PRIVILEGED },
|
|
{ SCMP_SYS(setfsgid), QEMU_SECCOMP_SET_PRIVILEGED },
|
|
/* spawn */
|
|
{ SCMP_SYS(fork), QEMU_SECCOMP_SET_SPAWN },
|
|
{ SCMP_SYS(vfork), QEMU_SECCOMP_SET_SPAWN },
|
|
{ SCMP_SYS(execve), QEMU_SECCOMP_SET_SPAWN },
|
|
/* resource control */
|
|
{ SCMP_SYS(getpriority), QEMU_SECCOMP_SET_RESOURCECTL },
|
|
{ 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,
|
|
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_max), 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_kill_action(void)
|
|
{
|
|
#if defined(SECCOMP_GET_ACTION_AVAIL) && defined(SCMP_ACT_KILL_PROCESS) && \
|
|
defined(SECCOMP_RET_KILL_PROCESS)
|
|
{
|
|
uint32_t action = SECCOMP_RET_KILL_PROCESS;
|
|
|
|
if (qemu_seccomp(SECCOMP_GET_ACTION_AVAIL, 0, &action) == 0) {
|
|
return SCMP_ACT_KILL_PROCESS;
|
|
}
|
|
}
|
|
#endif
|
|
|
|
return SCMP_ACT_TRAP;
|
|
}
|
|
|
|
|
|
static int seccomp_start(uint32_t seccomp_opts)
|
|
{
|
|
int rc = 0;
|
|
unsigned int i = 0;
|
|
scmp_filter_ctx ctx;
|
|
uint32_t action = qemu_seccomp_get_kill_action();
|
|
|
|
ctx = seccomp_init(SCMP_ACT_ALLOW);
|
|
if (ctx == NULL) {
|
|
rc = -1;
|
|
goto seccomp_return;
|
|
}
|
|
|
|
rc = seccomp_attr_set(ctx, SCMP_FLTATR_CTL_TSYNC, 1);
|
|
if (rc != 0) {
|
|
goto seccomp_return;
|
|
}
|
|
|
|
for (i = 0; i < ARRAY_SIZE(blacklist); i++) {
|
|
if (!(seccomp_opts & blacklist[i].set)) {
|
|
continue;
|
|
}
|
|
|
|
rc = seccomp_rule_add_array(ctx, action, blacklist[i].num,
|
|
blacklist[i].narg, blacklist[i].arg_cmp);
|
|
if (rc < 0) {
|
|
goto seccomp_return;
|
|
}
|
|
}
|
|
|
|
rc = seccomp_load(ctx);
|
|
|
|
seccomp_return:
|
|
seccomp_release(ctx);
|
|
return rc;
|
|
}
|
|
|
|
#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) < 0) {
|
|
error_setg(errp, "failed to install seccomp syscall filter "
|
|
"in the kernel");
|
|
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
|