[qemu.git] / qemu-seccomp.c

/*
 * QEMU seccomp mode 2 support with libseccomp
 *
 * Copyright IBM, Corp. 2012
 *
 * Authors:
 *  Eduardo Otubo    <[email protected]>
 *
 * 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_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();
    }
}


static int seccomp_start(uint32_t seccomp_opts, Error **errp)
{
    int rc = -1;
    unsigned int i = 0;
    scmp_filter_ctx ctx;

    ctx = seccomp_init(SCMP_ACT_ALLOW);
    if (ctx == NULL) {
        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;
        }

        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 < 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
Commit	Line	Data
2f668be7 EO	1	/*
	2	* QEMU seccomp mode 2 support with libseccomp
	3	*
	4	* Copyright IBM, Corp. 2012
	5	*
	6	* Authors:
	7	* Eduardo Otubo <[email protected]>
	8	*
	9	* This work is licensed under the terms of the GNU GPL, version 2. See
	10	* the COPYING file in the top-level directory.
	11	*
	12	* Contributions after 2012-01-13 are licensed under the terms of the
	13	* GNU GPL, version 2 or (at your option) any later version.
	14	*/
65484597	15
d38ea87a	16	#include "qemu/osdep.h"
65484597	17	#include "qapi/error.h"
9d0fdecb YMZ	18	#include "qemu/config-file.h"
	19	#include "qemu/option.h"
	20	#include "qemu/module.h"
9d0fdecb	21	#include <sys/prctl.h>
2f668be7	22	#include <seccomp.h>
9c17d615	23	#include "sysemu/seccomp.h"
bda08a57	24	#include <linux/seccomp.h>
2f668be7	25
81bed73b JH	26	/* For some architectures (notably ARM) cacheflush is not supported until
	27	* libseccomp 2.2.3, but configure enforces that we are using a more recent
	28	* version on those hosts, so it is OK for this check to be less strict.
	29	*/
47d2067a AJ	30	#if SCMP_VER_MAJOR >= 3
47d2067a AJ	31	#define HAVE_CACHEFLUSH
81bed73b	32	#elif SCMP_VER_MAJOR == 2 && SCMP_VER_MINOR >= 2
47d2067a AJ	33	#define HAVE_CACHEFLUSH
	34	#endif
	35
2f668be7 EO	36	struct QemuSeccompSyscall {
2f668be7 EO	37	int32_t num;
1bd6152a	38	uint8_t set;
056de1e8 MAL	39	uint8_t narg;
	40	const struct scmp_arg_cmp *arg_cmp;
	41	};
	42
	43	const struct scmp_arg_cmp sched_setscheduler_arg[] = {
e81e7b52 TH	44	/* was SCMP_A1(SCMP_CMP_NE, SCHED_IDLE), but expanded due to GCC 4.x bug */
e81e7b52 TH	45	{ .arg = 1, .op = SCMP_CMP_NE, .datum_a = SCHED_IDLE }
2f668be7 EO	46	};
2f668be7 EO	47
1bd6152a EO	48	static const struct QemuSeccompSyscall blacklist[] = {
	49	/* default set of syscalls to blacklist */
	50	{ SCMP_SYS(reboot), QEMU_SECCOMP_SET_DEFAULT },
	51	{ SCMP_SYS(swapon), QEMU_SECCOMP_SET_DEFAULT },
	52	{ SCMP_SYS(swapoff), QEMU_SECCOMP_SET_DEFAULT },
	53	{ SCMP_SYS(syslog), QEMU_SECCOMP_SET_DEFAULT },
	54	{ SCMP_SYS(mount), QEMU_SECCOMP_SET_DEFAULT },
	55	{ SCMP_SYS(umount), QEMU_SECCOMP_SET_DEFAULT },
	56	{ SCMP_SYS(kexec_load), QEMU_SECCOMP_SET_DEFAULT },
	57	{ SCMP_SYS(afs_syscall), QEMU_SECCOMP_SET_DEFAULT },
	58	{ SCMP_SYS(break), QEMU_SECCOMP_SET_DEFAULT },
	59	{ SCMP_SYS(ftime), QEMU_SECCOMP_SET_DEFAULT },
	60	{ SCMP_SYS(getpmsg), QEMU_SECCOMP_SET_DEFAULT },
	61	{ SCMP_SYS(gtty), QEMU_SECCOMP_SET_DEFAULT },
	62	{ SCMP_SYS(lock), QEMU_SECCOMP_SET_DEFAULT },
	63	{ SCMP_SYS(mpx), QEMU_SECCOMP_SET_DEFAULT },
	64	{ SCMP_SYS(prof), QEMU_SECCOMP_SET_DEFAULT },
	65	{ SCMP_SYS(profil), QEMU_SECCOMP_SET_DEFAULT },
	66	{ SCMP_SYS(putpmsg), QEMU_SECCOMP_SET_DEFAULT },
	67	{ SCMP_SYS(security), QEMU_SECCOMP_SET_DEFAULT },
	68	{ SCMP_SYS(stty), QEMU_SECCOMP_SET_DEFAULT },
	69	{ SCMP_SYS(tuxcall), QEMU_SECCOMP_SET_DEFAULT },
	70	{ SCMP_SYS(ulimit), QEMU_SECCOMP_SET_DEFAULT },
	71	{ SCMP_SYS(vserver), QEMU_SECCOMP_SET_DEFAULT },
2b716fa6 EO	72	/* obsolete */
	73	{ SCMP_SYS(readdir), QEMU_SECCOMP_SET_OBSOLETE },
	74	{ SCMP_SYS(_sysctl), QEMU_SECCOMP_SET_OBSOLETE },
	75	{ SCMP_SYS(bdflush), QEMU_SECCOMP_SET_OBSOLETE },
	76	{ SCMP_SYS(create_module), QEMU_SECCOMP_SET_OBSOLETE },
	77	{ SCMP_SYS(get_kernel_syms), QEMU_SECCOMP_SET_OBSOLETE },
	78	{ SCMP_SYS(query_module), QEMU_SECCOMP_SET_OBSOLETE },
	79	{ SCMP_SYS(sgetmask), QEMU_SECCOMP_SET_OBSOLETE },
	80	{ SCMP_SYS(ssetmask), QEMU_SECCOMP_SET_OBSOLETE },
	81	{ SCMP_SYS(sysfs), QEMU_SECCOMP_SET_OBSOLETE },
	82	{ SCMP_SYS(uselib), QEMU_SECCOMP_SET_OBSOLETE },
	83	{ SCMP_SYS(ustat), QEMU_SECCOMP_SET_OBSOLETE },
73a1e647 EO	84	/* privileged */
	85	{ SCMP_SYS(setuid), QEMU_SECCOMP_SET_PRIVILEGED },
	86	{ SCMP_SYS(setgid), QEMU_SECCOMP_SET_PRIVILEGED },
	87	{ SCMP_SYS(setpgid), QEMU_SECCOMP_SET_PRIVILEGED },
	88	{ SCMP_SYS(setsid), QEMU_SECCOMP_SET_PRIVILEGED },
	89	{ SCMP_SYS(setreuid), QEMU_SECCOMP_SET_PRIVILEGED },
	90	{ SCMP_SYS(setregid), QEMU_SECCOMP_SET_PRIVILEGED },
	91	{ SCMP_SYS(setresuid), QEMU_SECCOMP_SET_PRIVILEGED },
	92	{ SCMP_SYS(setresgid), QEMU_SECCOMP_SET_PRIVILEGED },
	93	{ SCMP_SYS(setfsuid), QEMU_SECCOMP_SET_PRIVILEGED },
	94	{ SCMP_SYS(setfsgid), QEMU_SECCOMP_SET_PRIVILEGED },
995a226f EO	95	/* spawn */
	96	{ SCMP_SYS(fork), QEMU_SECCOMP_SET_SPAWN },
	97	{ SCMP_SYS(vfork), QEMU_SECCOMP_SET_SPAWN },
	98	{ SCMP_SYS(execve), QEMU_SECCOMP_SET_SPAWN },
24f8cdc5 EO	99	/* resource control */
	100	{ SCMP_SYS(getpriority), QEMU_SECCOMP_SET_RESOURCECTL },
	101	{ SCMP_SYS(setpriority), QEMU_SECCOMP_SET_RESOURCECTL },
	102	{ SCMP_SYS(sched_setparam), QEMU_SECCOMP_SET_RESOURCECTL },
	103	{ SCMP_SYS(sched_getparam), QEMU_SECCOMP_SET_RESOURCECTL },
056de1e8 MAL	104	{ SCMP_SYS(sched_setscheduler), QEMU_SECCOMP_SET_RESOURCECTL,
056de1e8 MAL	105	ARRAY_SIZE(sched_setscheduler_arg), sched_setscheduler_arg },
24f8cdc5 EO	106	{ SCMP_SYS(sched_getscheduler), QEMU_SECCOMP_SET_RESOURCECTL },
	107	{ SCMP_SYS(sched_setaffinity), QEMU_SECCOMP_SET_RESOURCECTL },
	108	{ SCMP_SYS(sched_getaffinity), QEMU_SECCOMP_SET_RESOURCECTL },
	109	{ SCMP_SYS(sched_get_priority_max), QEMU_SECCOMP_SET_RESOURCECTL },
	110	{ SCMP_SYS(sched_get_priority_min), QEMU_SECCOMP_SET_RESOURCECTL },
2f668be7 EO	111	};
2f668be7 EO	112
bda08a57 MAL	113	static inline __attribute__((unused)) int
	114	qemu_seccomp(unsigned int operation, unsigned int flags, void *args)
	115	{
	116	#ifdef __NR_seccomp
	117	return syscall(__NR_seccomp, operation, flags, args);
	118	#else
	119	errno = ENOSYS;
	120	return -1;
	121	#endif
	122	}
	123
9a1565a0	124	static uint32_t qemu_seccomp_get_action(int set)
bda08a57	125	{
9a1565a0 DB	126	switch (set) {
	127	case QEMU_SECCOMP_SET_DEFAULT:
	128	case QEMU_SECCOMP_SET_OBSOLETE:
	129	case QEMU_SECCOMP_SET_PRIVILEGED:
	130	case QEMU_SECCOMP_SET_SPAWN: {
bda08a57 MAL	131	#if defined(SECCOMP_GET_ACTION_AVAIL) && defined(SCMP_ACT_KILL_PROCESS) && \
bda08a57 MAL	132	defined(SECCOMP_RET_KILL_PROCESS)
9a1565a0 DB	133	static int kill_process = -1;
	134	if (kill_process == -1) {
	135	uint32_t action = SECCOMP_RET_KILL_PROCESS;
bda08a57	136
9a1565a0 DB	137	if (qemu_seccomp(SECCOMP_GET_ACTION_AVAIL, 0, &action) == 0) {
	138	kill_process = 1;
	139	}
	140	kill_process = 0;
	141	}
	142	if (kill_process == 1) {
bda08a57 MAL	143	return SCMP_ACT_KILL_PROCESS;
bda08a57 MAL	144	}
bda08a57	145	#endif
9a1565a0 DB	146	return SCMP_ACT_TRAP;
9a1565a0 DB	147	}
bda08a57	148
9a1565a0 DB	149	case QEMU_SECCOMP_SET_RESOURCECTL:
	150	return SCMP_ACT_ERRNO(EPERM);
	151
	152	default:
	153	g_assert_not_reached();
	154	}
bda08a57 MAL	155	}
bda08a57 MAL	156
2b716fa6	157
035121d2	158	static int seccomp_start(uint32_t seccomp_opts, Error **errp)
2f668be7	159	{
035121d2	160	int rc = -1;
2f668be7 EO	161	unsigned int i = 0;
	162	scmp_filter_ctx ctx;
	163
1bd6152a	164	ctx = seccomp_init(SCMP_ACT_ALLOW);
2f668be7	165	if (ctx == NULL) {
035121d2	166	error_setg(errp, "failed to initialize seccomp context");
2f668be7 EO	167	goto seccomp_return;
	168	}
	169
70dfabea MAL	170	rc = seccomp_attr_set(ctx, SCMP_FLTATR_CTL_TSYNC, 1);
70dfabea MAL	171	if (rc != 0) {
035121d2 DB	172	error_setg_errno(errp, -rc,
035121d2 DB	173	"failed to set seccomp thread synchronization");
70dfabea MAL	174	goto seccomp_return;
	175	}
	176
1bd6152a	177	for (i = 0; i < ARRAY_SIZE(blacklist); i++) {
9a1565a0	178	uint32_t action;
2b716fa6 EO	179	if (!(seccomp_opts & blacklist[i].set)) {
	180	continue;
	181	}
	182
9a1565a0	183	action = qemu_seccomp_get_action(blacklist[i].set);
bda08a57	184	rc = seccomp_rule_add_array(ctx, action, blacklist[i].num,
056de1e8	185	blacklist[i].narg, blacklist[i].arg_cmp);
2f668be7	186	if (rc < 0) {
035121d2 DB	187	error_setg_errno(errp, -rc,
035121d2 DB	188	"failed to add seccomp blacklist rules");
2f668be7 EO	189	goto seccomp_return;
	190	}
	191	}
	192
	193	rc = seccomp_load(ctx);
035121d2 DB	194	if (rc < 0) {
	195	error_setg_errno(errp, -rc,
	196	"failed to load seccomp syscall filter in kernel");
	197	}
2f668be7 EO	198
	199	seccomp_return:
	200	seccomp_release(ctx);
035121d2	201	return rc < 0 ? -1 : 0;
2f668be7	202	}
9d0fdecb YMZ	203
	204	#ifdef CONFIG_SECCOMP
	205	int parse_sandbox(void opaque, QemuOpts opts, Error **errp)
	206	{
	207	if (qemu_opt_get_bool(opts, "enable", false)) {
	208	uint32_t seccomp_opts = QEMU_SECCOMP_SET_DEFAULT
	209	\| QEMU_SECCOMP_SET_OBSOLETE;
	210	const char *value = NULL;
	211
	212	value = qemu_opt_get(opts, "obsolete");
	213	if (value) {
	214	if (g_str_equal(value, "allow")) {
	215	seccomp_opts &= ~QEMU_SECCOMP_SET_OBSOLETE;
	216	} else if (g_str_equal(value, "deny")) {
	217	/* this is the default option, this if is here
	218	* to provide a little bit of consistency for
	219	* the command line */
	220	} else {
65484597	221	error_setg(errp, "invalid argument for obsolete");
9d0fdecb YMZ	222	return -1;
	223	}
	224	}
	225
	226	value = qemu_opt_get(opts, "elevateprivileges");
	227	if (value) {
	228	if (g_str_equal(value, "deny")) {
	229	seccomp_opts \|= QEMU_SECCOMP_SET_PRIVILEGED;
	230	} else if (g_str_equal(value, "children")) {
	231	seccomp_opts \|= QEMU_SECCOMP_SET_PRIVILEGED;
	232
	233	/* calling prctl directly because we're
	234	* not sure if host has CAP_SYS_ADMIN set*/
	235	if (prctl(PR_SET_NO_NEW_PRIVS, 1)) {
65484597	236	error_setg(errp, "failed to set no_new_privs aborting");
9d0fdecb YMZ	237	return -1;
	238	}
	239	} else if (g_str_equal(value, "allow")) {
	240	/* default value */
	241	} else {
65484597	242	error_setg(errp, "invalid argument for elevateprivileges");
9d0fdecb YMZ	243	return -1;
	244	}
	245	}
	246
	247	value = qemu_opt_get(opts, "spawn");
	248	if (value) {
	249	if (g_str_equal(value, "deny")) {
	250	seccomp_opts \|= QEMU_SECCOMP_SET_SPAWN;
	251	} else if (g_str_equal(value, "allow")) {
	252	/* default value */
	253	} else {
65484597	254	error_setg(errp, "invalid argument for spawn");
9d0fdecb YMZ	255	return -1;
	256	}
	257	}
	258
	259	value = qemu_opt_get(opts, "resourcecontrol");
	260	if (value) {
	261	if (g_str_equal(value, "deny")) {
	262	seccomp_opts \|= QEMU_SECCOMP_SET_RESOURCECTL;
	263	} else if (g_str_equal(value, "allow")) {
	264	/* default value */
	265	} else {
65484597	266	error_setg(errp, "invalid argument for resourcecontrol");
9d0fdecb YMZ	267	return -1;
	268	}
	269	}
	270
035121d2	271	if (seccomp_start(seccomp_opts, errp) < 0) {
9d0fdecb YMZ	272	return -1;
	273	}
	274	}
	275
	276	return 0;
	277	}
	278
	279	static QemuOptsList qemu_sandbox_opts = {
	280	.name = "sandbox",
	281	.implied_opt_name = "enable",
	282	.head = QTAILQ_HEAD_INITIALIZER(qemu_sandbox_opts.head),
	283	.desc = {
	284	{
	285	.name = "enable",
	286	.type = QEMU_OPT_BOOL,
	287	},
	288	{
	289	.name = "obsolete",
	290	.type = QEMU_OPT_STRING,
	291	},
	292	{
	293	.name = "elevateprivileges",
	294	.type = QEMU_OPT_STRING,
	295	},
	296	{
	297	.name = "spawn",
	298	.type = QEMU_OPT_STRING,
	299	},
	300	{
	301	.name = "resourcecontrol",
	302	.type = QEMU_OPT_STRING,
	303	},
	304	{ /* end of list */ }
	305	},
	306	};
	307
	308	static void seccomp_register(void)
	309	{
5780760f MAL	310	bool add = false;
	311
	312	/* FIXME: use seccomp_api_get() >= 2 check when released */
	313
	314	#if defined(SECCOMP_FILTER_FLAG_TSYNC)
	315	int check;
	316
	317	/* check host TSYNC capability, it returns errno == ENOSYS if unavailable */
	318	check = qemu_seccomp(SECCOMP_SET_MODE_FILTER,
	319	SECCOMP_FILTER_FLAG_TSYNC, NULL);
	320	if (check < 0 && errno == EFAULT) {
	321	add = true;
	322	}
	323	#endif
	324
	325	if (add) {
	326	qemu_add_opts(&qemu_sandbox_opts);
	327	}
9d0fdecb YMZ	328	}
	329	opts_init(seccomp_register);
	330	#endif