[daemon] Change permissions for instances to root only

include/multipass/platform.h

@@ -59,7 +59,8 @@ class Platform : public Singleton<Platform>
     virtual bool is_backend_supported(const QString& backend) const; // temporary (?)
     virtual int chown(const char* path, unsigned int uid, unsigned int gid) const;
     virtual int chmod(const char* path, unsigned int mode) const;
-    virtual bool set_permissions(const multipass::Path path, const QFileDevice::Permissions permissions) const;
+    virtual bool set_permissions(const multipass::Path& path, const QFileDevice::Permissions permissions) const;
+    virtual bool set_root_as_owner(const multipass::Path& path) const;
     virtual bool link(const char* target, const char* link) const;
     virtual bool symlink(const char* target, const char* link, bool is_dir) const;
     virtual int utime(const char* path, int atime, int mtime) const;

src/daemon/default_vm_image_vault.cpp

@@ -645,7 +645,9 @@ QString mp::DefaultVMImageVault::extract_image_from(const VMImage& source_image,
                                                     const ProgressMonitor& monitor,
                                                     const mp::Path& dest_dir)
 {
-    MP_UTILS.make_dir(dest_dir);
+    MP_UTILS.make_dir(dest_dir, QFile::ReadOwner | QFile::WriteOwner | QFile::ExeOwner);
+    MP_PLATFORM.set_root_as_owner(dest_dir);
+
     QFileInfo file_info{source_image.image_path};
     const auto image_name = file_info.fileName().remove(".xz");
     const auto image_path = QDir(dest_dir).filePath(image_name);
@@ -655,7 +657,8 @@ QString mp::DefaultVMImageVault::extract_image_from(const VMImage& source_image,
 
 mp::VMImage mp::DefaultVMImageVault::image_instance_from(const VMImage& prepared_image, const mp::Path& dest_dir)
 {
-    MP_UTILS.make_dir(dest_dir);
+    MP_UTILS.make_dir(dest_dir, QFile::ReadOwner | QFile::WriteOwner | QFile::ExeOwner);
+    MP_PLATFORM.set_root_as_owner(dest_dir);
 
     return {mp::vault::copy(prepared_image.image_path, dest_dir),
             prepared_image.id,

src/iso/cloud_init_iso.cpp

@@ -20,6 +20,7 @@
 #include <multipass/cloud_init_iso.h>
 #include <multipass/file_ops.h>
 #include <multipass/format.h>
+#include <multipass/platform.h>
 #include <multipass/yaml_node_utils.h>
 
 #include <QFile>
@@ -536,6 +537,12 @@ void mp::CloudInitIso::write_to(const Path& path)
         throw std::runtime_error{fmt::format(
             "Failed to open file for writing during cloud-init generation: {}; path: {}", f.errorString(), path)};
 
+    if (!MP_PLATFORM.set_permissions(path, QFile::ReadOwner | QFile::WriteOwner))
+        throw std::runtime_error{fmt::format("Failed to set permissions during cloud-init generation: path: {}", path)};
+
+    if (!MP_PLATFORM.set_root_as_owner(path))
+        throw std::runtime_error{fmt::format("Failed to set owner during cloud-init generation: path: {}", path)};
+
     const uint32_t num_reserved_bytes = 32768u;
     const uint32_t num_reserved_blocks = num_blocks(num_reserved_bytes);
     f.seek(num_reserved_bytes);

src/platform/platform_unix.cpp

@@ -63,11 +63,16 @@ int mp::platform::Platform::chmod(const char* path, unsigned int mode) const
     return ::chmod(path, mode);
 }
 
-bool mp::platform::Platform::set_permissions(const mp::Path path, const QFileDevice::Permissions permissions) const
+bool mp::platform::Platform::set_permissions(const mp::Path& path, const QFileDevice::Permissions permissions) const
 {
     return QFile::setPermissions(path, permissions);
 }
 
+bool mp::platform::Platform::set_root_as_owner(const mp::Path& path) const
+{
+    return this->chown(path.toStdString().c_str(), 0, 0) == 0;
+}
+
 bool mp::platform::Platform::symlink(const char* target, const char* link, bool is_dir) const
 {
     return ::symlink(target, link) == 0;

src/utils/vm_image_vault_utils.cpp

@@ -16,6 +16,7 @@
  */
 
 #include <multipass/format.h>
+#include <multipass/platform.h>
 #include <multipass/vm_image_host.h>
 #include <multipass/vm_image_vault.h>
 #include <multipass/xz_image_decoder.h>
@@ -45,6 +46,10 @@ QString mp::vault::copy(const QString& file_name, const QDir& output_dir)
     const auto source_name = info.fileName();
     auto new_path = output_dir.filePath(source_name);
     QFile::copy(file_name, new_path);
+
+    MP_PLATFORM.set_permissions(new_path, QFile::ReadOwner | QFile::WriteOwner | QFile::ExeOwner);
+    MP_PLATFORM.set_root_as_owner(new_path);
+
     return new_path;
 }
 
@@ -90,6 +95,9 @@ QString mp::vault::extract_image(const mp::Path& image_path, const mp::ProgressM
 
     xz_decoder.decode_to(new_image_path, monitor);
 
+    MP_PLATFORM.set_permissions(new_image_path, QFile::ReadOwner | QFile::WriteOwner | QFile::ExeOwner);
+    MP_PLATFORM.set_root_as_owner(new_image_path);
+
     mp::vault::delete_file(image_path);
 
     return new_image_path;

tests/mock_platform.h

@@ -42,6 +42,11 @@ class MockPlatform : public platform::Platform
     MOCK_METHOD(bool, is_alias_supported, (const std::string&, const std::string&), (const, override));
     MOCK_METHOD(int, chmod, (const char*, unsigned int), (const, override));
     MOCK_METHOD(int, chown, (const char*, unsigned int, unsigned int), (const, override));
+    MOCK_METHOD(bool,
+                set_permissions,
+                (const multipass::Path& path, const QFileDevice::Permissions),
+                (const, override));
+    MOCK_METHOD(bool, set_root_as_owner, (const multipass::Path& path), (const, override));
     MOCK_METHOD(bool, link, (const char*, const char*), (const, override));
     MOCK_METHOD(bool, symlink, (const char*, const char*, bool), (const, override));
     MOCK_METHOD(int, utime, (const char*, int, int), (const, override));

tests/test_base_virtual_machine_factory.cpp

@@ -123,6 +123,11 @@ TEST_F(BaseFactory, networks_throws)
 // at this time.  Instead, just make sure an ISO image is created and has the expected path.
 TEST_F(BaseFactory, creates_cloud_init_iso_image)
 {
+    auto [mock_platform, platform_guard] = mpt::MockPlatform::inject();
+
+    ON_CALL(*mock_platform, set_permissions).WillByDefault(Return(true));
+    ON_CALL(*mock_platform, set_root_as_owner).WillByDefault(Return(true));
+
     MockBaseFactory factory;
     const std::string name{"foo"};
     const YAML::Node metadata{YAML::Load({fmt::format("name: {}", name)})}, vendor_data{metadata}, user_data{metadata},

tests/test_cloud_init_iso.cpp

@@ -17,6 +17,7 @@
 
 #include "common.h"
 #include "mock_file_ops.h"
+#include "mock_platform.h"
 #include "temp_dir.h"
 
 #include <multipass/cloud_init_iso.h>
@@ -51,9 +52,15 @@ struct CloudInitIso : public Test
     CloudInitIso()
     {
         iso_path = QDir{temp_dir.path()}.filePath("test.iso");
+
+        ON_CALL(mock_platform, set_permissions).WillByDefault(Return(true));
+        ON_CALL(mock_platform, set_root_as_owner).WillByDefault(Return(true));
     }
     mpt::TempDir temp_dir;
     QString iso_path;
+
+    const mpt::MockPlatform::GuardedMock attr{mpt::MockPlatform::inject<NiceMock>()};
+    mpt::MockPlatform& mock_platform = *attr.first;
 };
 
 TEST_F(CloudInitIso, check_contains_false)