Messages in this thread | | | From | (Eric W. Biederman) | Date | Wed, 16 Sep 2015 19:54:26 -0500 | Subject | Re: [PATCH v3 2/7] userns: Simpilify MNT_NODEV handling. |
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Andy Lutomirski <luto@amacapital.net> writes:
> On Wed, Sep 16, 2015 at 1:02 PM, Seth Forshee > <seth.forshee@canonical.com> wrote: >> From: "Eric W. Biederman" <ebiederm@xmission.com> >> >> - Consolidate the testing if a device node may be opened in a new >> function may_open_dev. >> >> - Move the check for allowing access to device nodes on filesystems >> not mounted in the initial user namespace from mount time to open >> time and include it in may_open_dev. >> >> This set of changes removes the implicit adding of MNT_NODEV which >> simplifies the logic in fs/namespace.c and removes a potentially >> problematic user visible difference in how normal and unprivileged >> mount namespaces work. >> >> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> > >> - /* Only in special cases allow devices from mounts >> - * created outside the initial user namespace. >> - */ >> - if (!(type->fs_flags & FS_USERNS_DEV_MOUNT)) { >> - flags |= MS_NODEV; >> - mnt_flags |= MNT_NODEV | MNT_LOCK_NODEV; >> - } > > This is an ABI change. It's probably okay, but I think the commit > message should make it clear what's happening.
You mean it should include in big flashing neon letters ***REGRESSION FIX*** ?
It is longer in coming than I had hoped. But that is part of the reason I did not fix the security hole this way. Getting the s_user_ns stuff just so has been non-trivial.
I do agree that because this is a user visible change we do need to keep our eyes peeled for pieces of userspace software that may depend on the exact details of the current behavior.
Eric
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