Git is changing my file's permissions when I push to server
This thread post offers a very good explanation:
This is by design. While the git data structure can technically store unix mode bits in its trees, it was found early on in git's history that respecting anything beyond a simple executable bit ended up being more cumbersome for git's normal use cases (i.e., people storing code or other shared files in a repository).
We could add in a config option to respect file modes, but it has generally been seen as not worthwhile. It solves only a part of the general metadata problem, as it omits owner and group names or ids, as well as extended metadata like ACLs.
If modes are important to you, the suggested fixes are one of:
Use a tool like "metastore" that can be called from git hooks, and will save and restore file permissions in a file that is tracked in the repository. Do note that when using such a tool there is a race condition in protecting files (i.e., git will create your file as 644, and then metastore will correct it to 600; in the meantime, somebody could read your file).
Depending on exactly what you're storing, it may make sense to keep your repository in another directory, protected by permissions, and then use a separate tool to deploy your files from the repository to their ultimate location (e.g., a Makefile or other install tool).