X-Git-Url: https://git.proxmox.com/?a=blobdiff_plain;f=qemu-seccomp.c;h=e0a1829b3ddc9732f357179b9c23ce4b48703efb;hb=28605a22f564860c885bde42ad91840e9aacec45;hp=f66613fc71736532f1c855468b578242adf0127e;hpb=1bd6152ae23549032ef4aca0d3d350512f012f05;p=mirror_qemu.git

diff --git a/qemu-seccomp.c b/qemu-seccomp.c
index f66613fc71..e0a1829b3d 100644
--- a/qemu-seccomp.c
+++ b/qemu-seccomp.c
@@ -12,9 +12,16 @@
  * 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
@@ -29,6 +36,13 @@
 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[] = {
@@ -55,30 +69,262 @@ static const struct QemuSeccompSyscall blacklist[] = {
     { 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 },
 };
 
-int seccomp_start(void)
+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)
 {
-    int rc = 0;
+    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) {
-        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++) {
-        rc = seccomp_rule_add(ctx, SCMP_ACT_KILL, blacklist[i].num, 0);
+        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;
+    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