From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Yi Min Zhao <zyimin@linux.ibm.com>
Date: Thu, 31 May 2018 11:29:37 +0800
Subject: [PATCH] sandbox: disable -sandbox if CONFIG_SECCOMP undefined
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If CONFIG_SECCOMP is undefined, the option 'elevatedprivileges' remains
compiled. This would make libvirt set the corresponding capability and
then trigger failure during guest startup. This patch moves the code
regarding seccomp command line options to qemu-seccomp.c file and
wraps qemu_opts_foreach finding sandbox option with CONFIG_SECCOMP.
Because parse_sandbox() is moved into qemu-seccomp.c file, change
seccomp_start() to static function.

Signed-off-by: Yi Min Zhao <zyimin@linux.ibm.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
Tested-by: Ján Tomko <jtomko@redhat.com>
Acked-by: Eduardo Otubo <otubo@redhat.com>
(cherry picked from commit 9d0fdecbad130f01b602e35e87c6d3fad5821d6e)
[LD: BSC#1106222 CVE-2018-15746]
Signed-off-by: Larry Dewey <ldewey@suse.com>
---
 include/sysemu/seccomp.h |   3 +-
 qemu-seccomp.c           | 121 ++++++++++++++++++++++++++++++++++++-
 vl.c                     | 127 +++------------------------------------
 3 files changed, 129 insertions(+), 122 deletions(-)

diff --git a/include/sysemu/seccomp.h b/include/sysemu/seccomp.h
index e67c2dc840..fe859894f6 100644
--- a/include/sysemu/seccomp.h
+++ b/include/sysemu/seccomp.h
@@ -21,7 +21,6 @@
 #define QEMU_SECCOMP_SET_SPAWN       (1 << 3)
 #define QEMU_SECCOMP_SET_RESOURCECTL (1 << 4)
 
-#include <seccomp.h>
+int parse_sandbox(void *opaque, QemuOpts *opts, Error **errp);
 
-int seccomp_start(uint32_t seccomp_opts);
 #endif
diff --git a/qemu-seccomp.c b/qemu-seccomp.c
index a29e54b87f..4729eb107f 100644
--- a/qemu-seccomp.c
+++ b/qemu-seccomp.c
@@ -13,6 +13,11 @@
  * GNU GPL, version 2 or (at your option) any later version.
  */
 #include "qemu/osdep.h"
+#include "qemu/config-file.h"
+#include "qemu/option.h"
+#include "qemu/module.h"
+#include "qemu/error-report.h"
+#include <sys/prctl.h>
 #include <seccomp.h>
 #include "sysemu/seccomp.h"
 #include <linux/seccomp.h>
@@ -131,7 +136,7 @@ static uint32_t qemu_seccomp_get_kill_action(void)
 }
 
 
-int seccomp_start(uint32_t seccomp_opts)
+static int seccomp_start(uint32_t seccomp_opts)
 {
     int rc = 0;
     unsigned int i = 0;
@@ -167,3 +172,117 @@ int seccomp_start(uint32_t seccomp_opts)
     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_report("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_report("failed to set no_new_privs "
+                                 "aborting");
+                    return -1;
+                }
+            } else if (g_str_equal(value, "allow")) {
+                /* default value */
+            } else {
+                error_report("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_report("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_report("invalid argument for resourcecontrol");
+                return -1;
+            }
+        }
+
+        if (seccomp_start(seccomp_opts) < 0) {
+            error_report("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)
+{
+    qemu_add_opts(&qemu_sandbox_opts);
+}
+opts_init(seccomp_register);
+#endif
diff --git a/vl.c b/vl.c
index efd2b58bf1..98bb3f4428 100644
--- a/vl.c
+++ b/vl.c
@@ -28,14 +28,7 @@
 #include "qemu/uuid.h"
 #include <sys/resource.h>
 
-#ifdef CONFIG_SECCOMP
 #include "sysemu/seccomp.h"
-#include "sys/prctl.h"
-#endif
-
-#if defined(CONFIG_VDE)
-#include <libvdeplug.h>
-#endif
 
 #ifdef CONFIG_SDL
 #if defined(__APPLE__) || defined(main)
@@ -263,35 +256,6 @@ static QemuOptsList qemu_rtc_opts = {
     },
 };
 
-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 QemuOptsList qemu_option_rom_opts = {
     .name = "option-rom",
     .implied_opt_name = "romfile",
@@ -1045,88 +1009,6 @@ static int bt_parse(const char *opt)
     return 1;
 }
 
-static int parse_sandbox(void *opaque, QemuOpts *opts, Error **errp)
-{
-    if (qemu_opt_get_bool(opts, "enable", false)) {
-#ifdef CONFIG_SECCOMP
-        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_report("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_report("failed to set no_new_privs "
-                                 "aborting");
-                    return -1;
-                }
-            } else if (g_str_equal(value, "allow")) {
-                /* default value */
-            } else {
-                error_report("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_report("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_report("invalid argument for resourcecontrol");
-                return -1;
-            }
-        }
-
-        if (seccomp_start(seccomp_opts) < 0) {
-            error_report("failed to install seccomp syscall filter "
-                         "in the kernel");
-            return -1;
-        }
-#else
-        error_report("seccomp support is disabled");
-        return -1;
-#endif
-    }
-
-    return 0;
-}
-
 static int parse_name(void *opaque, QemuOpts *opts, Error **errp)
 {
     const char *proc_name;
@@ -3109,7 +2991,6 @@ int main(int argc, char **argv, char **envp)
     qemu_add_opts(&qemu_mem_opts);
     qemu_add_opts(&qemu_smp_opts);
     qemu_add_opts(&qemu_boot_opts);
-    qemu_add_opts(&qemu_sandbox_opts);
     qemu_add_opts(&qemu_add_fd_opts);
     qemu_add_opts(&qemu_object_opts);
     qemu_add_opts(&qemu_tpmdev_opts);
@@ -4090,11 +3971,17 @@ int main(int argc, char **argv, char **envp)
                 qtest_log = optarg;
                 break;
             case QEMU_OPTION_sandbox:
+#ifdef CONFIG_SECCOMP
                 opts = qemu_opts_parse_noisily(qemu_find_opts("sandbox"),
                                                optarg, true);
                 if (!opts) {
                     exit(1);
                 }
+#else
+                error_report("-sandbox support is not enabled "
+                             "in this QEMU binary");
+                exit(1);
+#endif
                 break;
             case QEMU_OPTION_add_fd:
 #ifndef _WIN32
@@ -4173,10 +4060,12 @@ int main(int argc, char **argv, char **envp)
         exit(1);
     }
 
+#ifdef CONFIG_SECCOMP
     if (qemu_opts_foreach(qemu_find_opts("sandbox"),
                           parse_sandbox, NULL, NULL)) {
         exit(1);
     }
+#endif
 
     if (qemu_opts_foreach(qemu_find_opts("name"),
                           parse_name, NULL, NULL)) {
