Index: src/ioslaves/file/file.h
===================================================================
--- src/ioslaves/file/file.h
+++ src/ioslaves/file/file.h
@@ -105,6 +105,7 @@
     PrivilegeOperationReturnValue execWithElevatedPrivilege(ActionType action, const QVariant &arg1,
                                                             const QVariant &arg2 = QVariant(),
                                                             const QVariant &arg3 = QVariant());
+    PrivilegeOperationReturnValue tryOpen(QFile &f, const QByteArray &path, int flags, int mode);
 private:
     mutable QHash<KUserId, QString> mUsercache;
     mutable QHash<KGroupId, QString> mGroupcache;
Index: src/ioslaves/file/file_unix.cpp
===================================================================
--- src/ioslaves/file/file_unix.cpp
+++ src/ioslaves/file/file_unix.cpp
@@ -41,6 +41,8 @@
 
 #include <KAuth>
 
+#include "sharefd.h"
+
 //sendfile has different semantics in different platforms
 #if defined HAVE_SENDFILE && defined Q_OS_LINUX
 #define USE_SENDFILE 1
@@ -70,6 +72,45 @@
     return QStringLiteral("org_kde_kio_file_helper_%1").arg(getpid());
 }
 
+PrivilegeOperationReturnValue FileProtocol::tryOpen(QFile &f, const QByteArray &path, int flags, int mode)
+{
+    FdReceiver fdRecv(socketPath());
+    if (!fdRecv.isValid()) {
+        return PrivilegeOperationReturnValue::failure();
+    }
+
+    int fd = fdRecv.fileDescriptor();
+    if (fd == -1) {
+        return PrivilegeOperationReturnValue::failure();
+    }
+
+    QIODevice::OpenMode openMode;
+    if (flags & O_RDONLY) {
+        openMode |= QIODevice::ReadOnly;
+    }
+    if (flags & O_WRONLY || flags & O_CREAT) {
+        openMode |= QIODevice::WriteOnly;
+    }
+    if (flags & O_RDWR) {
+        openMode |= QIODevice::ReadWrite;
+    }
+    if (flags & O_TRUNC) {
+        openMode |= QIODevice::Truncate;
+    }
+    if (flags & O_APPEND) {
+        openMode |= QIODevice::Append;
+    }
+
+    if (auto err = execWithElevatedPrivilege(OPEN, path, flags, mode)) {
+        return err;
+    } else {
+        if (!f.open(fd, openMode, QFileDevice::AutoCloseHandle)) {
+            return PrivilegeOperationReturnValue::failure();
+        }
+    }
+    return PrivilegeOperationReturnValue::success();
+}
+
 void FileProtocol::copy(const QUrl &srcUrl, const QUrl &destUrl,
                         int _mode, JobFlags _flags)
 {
@@ -125,34 +166,60 @@
         // the symlink actually points to current source!
         if ((_flags & KIO::Overwrite) && ((buff_dest.st_mode & QT_STAT_MASK) == QT_STAT_LNK)) {
             //qDebug() << "copy(): LINK DESTINATION";
-            QFile::remove(dest);
+            if (!QFile::remove(dest)) {
+                if (auto err = execWithElevatedPrivilege(DEL, _dest)) {
+                    if (!err.wasCanceled()) {
+                        error(KIO::ERR_CANNOT_DELETE_ORIGINAL, dest);
+                    }
+                    return;
+                }
+            }
         }
     }
 
     QFile src_file(src);
     if (!src_file.open(QIODevice::ReadOnly)) {
-        error(KIO::ERR_CANNOT_OPEN_FOR_READING, src);
-        return;
+        if (auto err = tryOpen(src_file, _src, O_RDONLY, S_IRUSR)) {
+            if (!err.wasCanceled()) {
+                error(KIO::ERR_CANNOT_OPEN_FOR_READING, src);
+            }
+            return;
+        }
     }
 
 #if HAVE_FADVISE
     posix_fadvise(src_file.handle(), 0, 0, POSIX_FADV_SEQUENTIAL);
 #endif
 
     QFile dest_file(dest);
     if (!dest_file.open(QIODevice::Truncate | QIODevice::WriteOnly)) {
-        // qDebug() << "###### COULD NOT WRITE " << dest;
-        if (errno == EACCES) {
-            error(KIO::ERR_WRITE_ACCESS_DENIED, dest);
-        } else {
-            error(KIO::ERR_CANNOT_OPEN_FOR_WRITING, dest);
+        if (auto err = tryOpen(dest_file, _dest, O_WRONLY | O_TRUNC | O_CREAT, S_IRUSR | S_IWUSR)) {
+            if (!err.wasCanceled()) {
+                // qDebug() << "###### COULD NOT WRITE " << dest;
+                if (errno == EACCES) {
+                    error(KIO::ERR_WRITE_ACCESS_DENIED, dest);
+                } else {
+                    error(KIO::ERR_CANNOT_OPEN_FOR_WRITING, dest);
+                }
+            }
+            src_file.close();
+            return;
         }
-        src_file.close();
-        return;
     }
 
     // nobody shall be allowed to peek into the file during creation
-    dest_file.setPermissions(QFileDevice::ReadOwner | QFileDevice::WriteOwner);
+    if (!dest_file.setPermissions(QFileDevice::ReadOwner | QFileDevice::WriteOwner)) {
+        if (auto err = execWithElevatedPrivilege(CHOWN, _dest, getuid(), getgid())) {
+            dest_file.close();
+            execWithElevatedPrivilege(DEL, _dest);
+            if (!err.wasCanceled()) {
+                error(KIO::ERR_CANNOT_CHOWN, dest);
+            }
+            return;
+        } else {
+            dest_file.setPermissions(QFileDevice::ReadOwner | QFileDevice::WriteOwner);
+        }
+    }
 
 #if HAVE_FADVISE
     posix_fadvise(dest_file.handle(), 0, 0, POSIX_FADV_SEQUENTIAL);
@@ -213,7 +280,9 @@
                 acl_free(acl);
             }
 #endif
-            dest_file.remove();  // don't keep partly copied file
+            if (!QFile::remove(dest)) {  // don't keep partly copied file
+                execWithElevatedPrivilege(DEL, _dest);
+            }
             return;
         }
         if (n == 0) {
@@ -234,7 +303,9 @@
                     acl_free(acl);
                 }
 #endif
-                dest_file.remove();  // don't keep partly copied file
+                if (!QFile::remove(dest)) {  // don't keep partly copied file
+                    execWithElevatedPrivilege(DEL, _dest);
+                }
                 return;
             }
             processed_size += n;
@@ -255,7 +326,9 @@
             acl_free(acl);
         }
 #endif
-        dest_file.remove();  // don't keep partly copied file
+        if (!QFile::remove(dest)) {  // don't keep partly copied file
+            execWithElevatedPrivilege(DEL, _dest);
+        }
         return;
     }
 
@@ -270,10 +343,10 @@
         || (acl && acl_set_file(_dest.data(), ACL_TYPE_ACCESS, acl) != 0)
 #endif
        ) {
-        KMountPoint::Ptr mp = KMountPoint::currentMountPoints().findByPath(dest);
-        // Eat the error if the filesystem apparently doesn't support chmod.
-        if (mp && mp->testFileSystemFlag(KMountPoint::SupportsChmod)) {
-            warning(i18n("Could not change permissions for '%1'", dest));
+        if (auto err = execWithElevatedPrivilege(CHMOD, _dest, _mode)) {
+            if (!err.wasCanceled()) {
+                warning(i18n("Could not change permissions for '%1'", dest));
+            }
         }
     }
 #if HAVE_POSIX_ACL
@@ -288,15 +361,19 @@
         // we might not be allowed to change the owner
         (void)::chown(_dest.data(), buff_src.st_uid, -1 /*keep group*/);
     } else {
-        qCWarning(KIO_FILE) << QStringLiteral("Couldn't preserve group for '%1'").arg(dest);
+        if (execWithElevatedPrivilege(CHOWN, _dest, buff_src.st_uid, buff_src.st_gid)) {
+            qCWarning(KIO_FILE) << QStringLiteral("Couldn't preserve group for '%1'").arg(dest);
+        }
     }
 
     // copy access and modification time
     struct utimbuf ut;
     ut.actime = buff_src.st_atime;
     ut.modtime = buff_src.st_mtime;
     if (::utime(_dest.data(), &ut) != 0) {
-        qCWarning(KIO_FILE) << QStringLiteral("Couldn't preserve access and modification time for '%1'").arg(dest);
+        if (execWithElevatedPrivilege(UTIME, _dest, qint64(ut.actime), qint64(ut.modtime))) {
+            qCWarning(KIO_FILE) << QStringLiteral("Couldn't preserve access and modification time for '%1'").arg(dest);
+        }
     }
 
     processedSize(buff_src.st_size);