Ubuntu
linux-mako package

  1. Yakkety (16.10)
  2. Bug #1535150
  3. Comment #21

Comment 21 for bug 1535150

Revision history for this message
J. R. Okajima (hooanon05) wrote : Re: overlayfs over fuse should refuse copy_up of files if uid/gid not mapped

The security bug hunter halfdog kindly invited me here.

These 6 patches using the mounter's cred are interesting approach, but I have a question.
- mount(2) requires CAP_SYS_ADMIN only. CAP_CHOWN is not necessary.
- the internal copy-up requires CAP_CHOWN. CAP_DAC_OVERRIDE, CAP_FOWNER, CAP_FSETID, CAP_CHOWN, and CAP_MKNOD.

When the mounter doesn't have CAP_CHOWN and others, can a user open the file which is owned by another user?

Unfortunately my machine environment doesn't allow me to test it by myself.