Index: src/ioslaves/file/file_unix.cpp
===================================================================
--- src/ioslaves/file/file_unix.cpp
+++ src/ioslaves/file/file_unix.cpp
@@ -40,6 +40,7 @@
 #include <utime.h>
 
 #include <KAuth>
+#include "sharefd.h"
 
 //sendfile has different semantics in different platforms
 #if defined HAVE_SENDFILE && defined Q_OS_LINUX
@@ -120,14 +121,28 @@
         // 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 (!execWithElevatedPrivilege(DEL, _dest)) {
+                    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;
+        int src_fd = -1;
+        FdReceiver fdRecv;
+        bool _continue = (  fdRecv.startListening(QStringLiteral("org_kde_kio_file_helper_socket"))
+                         && execWithElevatedPrivilege(OPEN, _src, O_RDONLY, S_IRUSR)
+                         && (src_fd = fdRecv.fileDescriptor()) != -1
+                         && src_file.open(src_fd, QIODevice::ReadOnly, QFileDevice::AutoCloseHandle));
+
+        if (!_continue) {
+            error(KIO::ERR_CANNOT_OPEN_FOR_READING, src);
+            return;
+        }
     }
 
 #if HAVE_FADVISE
@@ -137,17 +152,35 @@
     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);
+        int dest_fd = -1;
+        FdReceiver fdRecv;
+        bool _continue = (  fdRecv.startListening(QStringLiteral("org_kde_kio_file_helper_socket"))
+                         && execWithElevatedPrivilege(OPEN, _dest, O_WRONLY | O_TRUNC | O_CREAT, S_IRUSR | S_IWUSR)
+                         && (dest_fd = fdRecv.fileDescriptor()) != -1
+                         && dest_file.open(dest_fd, QIODevice::WriteOnly | QIODevice::Truncate, QFileDevice::AutoCloseHandle));
+
+        if (!_continue) {
+            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 (!QFile::setPermissions(dest, QFileDevice::ReadOwner | QFileDevice::WriteOwner)) {
+        // File was created by root user with the above permissions. We only need to
+        // change its owner.
+        if (!execWithElevatedPrivilege(CHOWN, _dest, getuid(), getgid())) {
+            dest_file.close();
+            execWithElevatedPrivilege(DEL, _dest);
+            error(KIO::ERR_CANNOT_CHOWN, dest);
+            return;
+        }
+    }
 
 #if HAVE_FADVISE
     posix_fadvise(dest_file.handle(), 0, 0, POSIX_FADV_SEQUENTIAL);
@@ -208,7 +241,9 @@
                 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) {
@@ -229,7 +264,9 @@
                     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;
@@ -250,7 +287,9 @@
             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;
     }
 
@@ -265,10 +304,12 @@
         || (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 (!execWithElevatedPrivilege(CHMOD, _dest, _mode)) {
+            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 HAVE_POSIX_ACL
@@ -283,15 +324,19 @@
         // 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);
+        // atime and modtime are of type long so not usable with QVariant.
+        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);