I have a folder with the following permissions:
drwxrws--x+ 13 myuser www-data 4096 Mar 20 09:57 project-folder
In this folder I have an archive archive.zip with the following permissions:
-rw-rw----+ 1 myuser www-data 10260 Mar 20 09:56 archive.zip
When I unzipped archive by calling unzip archive.zip I got the following file listing:
drwxrwx--x+ 3 myuser www-data 4096 May 5 2017 folder-from-archive
As we can see, the owner group is www-data as same for parent folder project-folder, but the folder-from-archive does not have the setgid bit (the s in the permissions string) and the content of this folder is not owned by group www-data:
-rw-rw----+ 1 myuser myuser 1083 May 5 2017 LICENSE
-rw-rw----+ 1 myuser myuser 2197 May 5 2017 README.md
-rw-rw----+ 1 myuser myuser 720 May 5 2017 autoload.php
-rw-rw----+ 1 myuser myuser 786 May 5 2017 composer.json
drwxrwx--x+ 3 myuser myuser 4096 May 5 2017 source
But when I tried unzipping this archive as root user the permissions and group owner (as well as the files in the folder) were correct:
drwxr-s--x+ 3 root www-data 4096 May 5 2017 folder-from-archive
Files in folder folder-from-archive:
-rw-r-----+ 1 root www-data 1083 May 5 2017 LICENSE
-rw-r-----+ 1 root www-data 2197 May 5 2017 README.md
-rw-r-----+ 1 root www-data 720 May 5 2017 autoload.php
-rw-r-----+ 1 root www-data 786 May 5 2017 composer.json
drwxr-s--x+ 3 root www-data 4096 May 5 2017 source
As we can see after unzipping by root user the folder inherited the setgid bit and set correct group www-data for itself and all containing files.
How to get the same behavior for the user myuser?
That behavior was default but later it began to be considered as security issue (CVE-2005-0602).
unzip --helpshows argument that should help:-K keep setuid/setgid/tacky permissions. Therefore command should beunzip -K archive.zip.