From: "Sakkinen, Jarkko" <jarkko.sakkinen@intel.com>
To: Hugh Dickins <hughd@google.com>
Cc: "Ware, Ryan R" <ryan.r.ware@intel.com>,
Andrew Morton <akpm@linux-foundation.org>,
James Morris <jmorris@namei.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
linux-security-module@vger.kernel.org
Subject: Re: [PATCH] tmpfs: security xattr setting on inode creation
Date: Tue, 28 Feb 2012 07:51:26 +0200 [thread overview]
Message-ID: <CADjiTvCViw4tZ9HvH-s8a2_8uW82BwfXz3PLQmEEVAVC0PbDwg@mail.gmail.com> (raw)
In-Reply-To: <alpine.LSU.2.00.1202272003380.1574@eggly.anvils>
On Tue, Feb 28, 2012 at 6:10 AM, Hugh Dickins <hughd@google.com> wrote:
> On Tue, 28 Feb 2012, Ware, Ryan R wrote:
>> On Tue, Feb 28, 2012 at 7:46 AM, Andrew Morton <akpm@linux-foundation.org>wrote:
>> > On Fri, 24 Feb 2012 19:19:22 -0800 (PST)
>> > Hugh Dickins <hughd@google.com> wrote:
>> >...
>> > > + if (!new_xattr->name) {
>> > > + kfree(new_xattr);
>> > > + return -ENOMEM;
>> > > + }
>> > > +
>> > > + memcpy(new_xattr->name, XATTR_SECURITY_PREFIX,
>> > > + XATTR_SECURITY_PREFIX_LEN);
>> > > + memcpy(new_xattr->name + XATTR_SECURITY_PREFIX_LEN,
>> > > + xattr->name, len);
>> > > +
>> > > + spin_lock(&info->lock);
>> > > + list_add(&new_xattr->list, &info->xattr_list);
>> > > + spin_unlock(&info->lock);
>> > > + }
>> > > +
>> > > + return 0;
>> > > +}
>> >
>> > So if there's a kmalloc failure partway through the array, we leave a
>> > partially xattrified inode in place.
>> >
>> > Are we sure this is OK?
>> >
>>
>> I'm guessing Jarkko can clean that up a bit. It wouldn't be a good idea to
>> leave inaccurate data structures laying around during failure cases.
>
> Andrew raises a good concern, but Jarkko got it just right and no
> change is needed: any xattrs already allocated are properly linked
> on info->xattr_list, then when security_inode_init_security() fails
> (with an error other than EOPNOTSUPP) the failing inode is iput(),
> which ends up in shmem_evict_inode(), which kfree()s those xattrs
> (and their names) on info->xattr_list.
Yeah, that's how I understood it too. These the are places where
security_inode_init_security() is called:
- http://lxr.free-electrons.com/source/mm/shmem.c#L1459
- http://lxr.free-electrons.com/source/mm/shmem.c#L1590
>
> Hugh
/Jarkko
next prev parent reply other threads:[~2012-02-28 5:51 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-23 9:46 [PATCH] tmpfs: security xattr setting on inode creation Jarkko Sakkinen
2012-02-24 8:13 ` James Morris
2012-02-25 3:19 ` Hugh Dickins
2012-02-25 7:03 ` Sakkinen, Jarkko
2012-02-27 22:46 ` Andrew Morton
2012-02-28 3:46 ` Ware, Ryan R
[not found] ` <CAGGTEhPQ6OLgqZbbAwE=3Xj8qE2iNhLOk5LdkGU13WxbY=qb2w@mail.gmail.com>
2012-02-28 4:10 ` Hugh Dickins
2012-02-28 5:51 ` Sakkinen, Jarkko [this message]
-- strict thread matches above, loose matches on Subject: below --
2012-02-22 7:48 Jarkko Sakkinen
2012-02-22 17:46 ` Sakkinen, Jarkko
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