From 0997abc5b93ecdf81053c4b25846a36bfd055486 Mon Sep 17 00:00:00 2001 From: Eduard Zateev Date: Mon, 12 Oct 2026 21:00:41 +1000 Subject: [PATCH] docs: explain hardlink risks for writable binds Signed-off-by: Eduard Zateev --- README.md | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/README.md b/README.md index 69addd6f..41b20a7b 100644 --- a/README.md +++ b/README.md @@ -171,6 +171,12 @@ execute commands via systemd. You can use [xdg-dbus-proxy](https://github.com/flatpak/xdg-dbus-proxy) to filter D-Bus communication. +- Writable bind mounts expose the same files as the host. If another process +can write to the bound directory, it can create a hard link there to a file +outside the sandbox. Writes to that link from inside the sandbox also modify +the host file. If writable data needs to be isolated, put it on a separate +filesystem so hard links cannot cross the boundary. + - Some applications deploy their own sandboxing mechanisms, and these can be restricted by the constraints imposed by bubblewrap's sandboxing. For example, some web browsers which configure their child proccesses via