OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx> writes:
> Amerigo Wang <amwang@xxxxxxxxxx> writes:
>
>>> static int selinux_inode_setattr(struct dentry *dentry, struct iattr *iattr)
>>> {
>>> const struct cred *cred = current_cred();
>>>
>>> if (iattr->ia_valid & ATTR_FORCE)
>>> return 0;
>>>
>>> if (iattr->ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID |
>>> ATTR_ATIME_SET | ATTR_MTIME_SET))
>>> return dentry_has_perm(cred, NULL, dentry, FILE__SETATTR);
>>>
>>> return dentry_has_perm(cred, NULL, dentry, FILE__WRITE);
>>> }
>>>
>>> I guess it's assuming the ia_valid doesn't have (ATTR_MODE | ATTR_SIZE),
>>> but truncate() already does it, I don't know whether it's ok.
>>
>> No, here we should only force ATTR_KILL_SUID and/or ATTR_KILL_SGID.
>> do_truncate() has ATTR_SIZE and ATTR_FILE.
>
> I guess security module should do,
>
> ia_valid = iattr->ia_valid;
> if (!(ia_valid & ATTR_FORCE) && (ia_valid & ATTR_FORCE_MASK)) {
> err = dentry_has_perm(cred, NULL, dentry, FILE__SETATTR);
> if (err)
> return err;
> ia_valid &= ~ATTR_FORCE_MASK;
> }
> if (ia_valid & ATTR_NOT_FORCE_MASK)
> err = dentry_has_perm(cred, NULL, dentry, FILE__WRITE);
> return err;
>
> or something. Because do_truncate() already do (ATTR_MODE | ATTR_SIZE)
> without ATTR_FORCE.
BTW, it seems original code doesn't check ATTR_SIZE if (ATTR_MODE |
ATTR_SIZE), right? So, ATTR_FORCE is just forcing ATTR_MODE, but I
guess that's problem itself.
Thanks.
--
OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx>
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