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+---
+edit_link: ''
+title: File Systems
+origin_url: >-
+  https://raw.githubusercontent.com/automotive-grade-linux/docs-sources/master/docs/security-blueprint/part-4/5-FileSystems.md
+---
+
+<!-- WARNING: This file is generated by fetch_docs.js using /home/boron/Documents/AGL/docs-webtemplate/site/_data/tocs/architecture/master/security_blueprint-security-blueprint-book.yml -->
+
+# File System
+
+## Disable all file systems not needed
+
+To reduce the attack surface, file system data is parsed by the kernel, so any logic bugs in file system drivers can become kernel exploits.
+
+### Disable NFS file system
+
+NFS FileSystems are useful during development phases, but this can be a very helpful way for an attacker to get files when you are in production mode, so we must disable them.
+
+<!-- section-config -->
+
+Domain                   | `Config` name   | `Value`
+------------------------ | --------------- | -------
+Kernel-FileSystems-NFS-1 | `CONFIG_NFSD`   | `n`
+Kernel-FileSystems-NFS-2 | `CONFIG_NFS_FS` | `n`
+
+<!-- end-section-config -->
+
+--------------------------------------------------------------------------------
+
+<!-- pagebreak -->
+
+## Partition Mount Options
+
+There are several security restrictions that can be set on a filesystem when it is mounted. Some common security options include, but are not limited to:
+
+`nosuid` - Do not allow set-user-identifier or set-group-identifier bits to take effect.
+
+`nodev` - Do not interpret character or block special devices on the filesystem.
+
+`noexec` - Do not allow execution of any binaries on the mounted filesystem.
+
+`ro` - Mount filesystem as read-only.
+
+The following flags shall be used for mounting common filesystems:
+
+<!-- section-config -->
+
+Domain                     | `Partition`         | `Value`
+-------------------------- | ------------------- | -----------------------------------------------------------------
+Kernel-FileSystems-Mount-1 | `/boot`             | `nosuid`, `nodev` and `noexec`.
+Kernel-FileSystems-Mount-2 | `/var` & `/tmp`     | In `/etc/fstab` or `vfstab`, add `nosuid`, `nodev` and `noexec`.
+Kernel-FileSystems-Mount-3 | _Non-root local_    | If type is `ext2` or `ext3` and mount point not '/', add `nodev`.
+Kernel-FileSystems-Mount-4 | _Removable storage_ | Add `nosuid`, `nodev` and `noexec`.
+Kernel-FileSystems-Mount-5 | _Temporary storage_ | Add `nosuid`, `nodev` and `noexec`.
+Kernel-FileSystems-Mount-6 | `/dev/shm`          | Add `nosuid`, `nodev` and `noexec`.
+Kernel-FileSystems-Mount-7 | `/dev`              | Add `nosuid` and `noexec`.
+
+<!-- end-section-config --> <!-- section-note -->
+
+If `CONFIG_DEVTMPFS_MOUNT` is set, then the kernel will mount /dev and will not apply the `nosuid`, `noexec` options. Either disable `CONFIG_DEVTMPFS_MOUNT` or add a remount with `noexec` and `nosuid` options to system startup.
+
+<!-- end-section-note --> <!-- section-config -->
+
+Domain                     | `Config` name           | _State_ or `Value`
+-------------------------- | ----------------------- | -----------------------------------------------------------------------
+Kernel-FileSystems-Mount-1 | `CONFIG_DEVTMPFS_MOUNT` | _Disabled_ or add remount with `noexec` and `nosuid` to system startup.
+
+<!-- end-section-config -->