Re: [PATCH 7/8] SELinux: Create a common helper to determine an inode label

From: David Howells
Date: Thu Jun 18 2015 - 11:14:09 EST


Stephen Smalley <sds@xxxxxxxxxxxxx> wrote:

> > + if ((sbsec->flags & SE_SBINITIALIZED) &&
> > + (sbsec->behavior == SECURITY_FS_USE_MNTPOINT)) {
> > + *_new_isid = sbsec->mntpoint_sid;
> > + } else if (tsec->create_sid) {
>
> This doesn't quite match the logic in inode_init_security today, see its
> checking of SBLABEL_MNT.

Fair point. What does SBLABEL_MNT mean precisely? It seems to indicate one
of an odd mix of behaviours. I presume it means that we *have* to calculate a
label and can't get one from the underlying fs if it is not set.

Also, in:

sbsec->flags |= SE_SBINITIALIZED;
if (selinux_is_sblabel_mnt(sb))
sbsec->flags |= SBLABEL_MNT;

should SE_SBINITIALIZED be set after SBLABEL_MNT? And should there be a
memory barrier in here somewhere before the setting of SE_SBINITIALIZED?

David
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