On 06/18/2015 11:32 AM, David Howells wrote:
> Stephen Smalley <sds@xxxxxxxxxxxxx> wrote:
>
>>> 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.
>>
>> It means the filesystem supports per-file labeling and you can use
>> setxattr(..."security.selinux") and setfscreatecon() for files on it.
>> You can see whether it is set on a filesystem by looking for the
>> seclabel option in cat /proc/mounts. If it is not set, then we ignore
>> tsec->create_sid. It is arguable as to whether it is correct to always
>> call security_transition_sid() there either, but that's another topic.
>
> Okay, so how about the attached?
>
> David
> ---
> static int selinux_determine_inode_label(const struct inode *dir,
> const struct qstr *name,
> const char *caller,
> u16 tclass,
> u32 *_new_isid)
> {
> const struct superblock_security_struct *sbsec = dir->i_sb->s_security;
> const struct inode_security_struct *dsec = dir->i_security;
> const struct task_security_struct *tsec = current_security();
>
> if ((sbsec->flags & SE_SBINITIALIZED) &&
> (sbsec->behavior == SECURITY_FS_USE_MNTPOINT)) {
> *_new_isid = sbsec->mntpoint_sid;
> } else if ((sbsec->flags & SBLABEL_MNT) &&
> tsec->create_sid) {
> *_new_isid = tsec->create_sid;
> } else {
> return security_transition_sid(tsec->sid, dsec->sid, tclass,
> name, _new_isid);
> }
>
> return 0;
> }
That looks good to me. In fact, I'd take a patch that defines that
function and rewrites may_create(), inode_init_security(), and
dentry_init_security() to use it even before (or independent of) the
union support patches.
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