From: Vivek Goyal <vgoyal@redhat.com>
To: Stephen Smalley <sds@tycho.nsa.gov>
Cc: miklos@szeredi.hu, pmoore@redhat.com, casey@schaufler-ca.com,
linux-kernel@vger.kernel.org, linux-unionfs@vger.kernel.org,
linux-security-module@vger.kernel.org, dwalsh@redhat.com,
dhowells@redhat.com, viro@ZenIV.linux.org.uk,
linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH 1/7] security, overlayfs: provide copy up security hook for unioned files
Date: Mon, 11 Jul 2016 12:54:23 -0400 [thread overview]
Message-ID: <20160711165423.GB7728@redhat.com> (raw)
In-Reply-To: <26a1232e-09b2-e89b-22c3-7414dd11e79c@tycho.nsa.gov>
On Mon, Jul 11, 2016 at 11:24:26AM -0400, Stephen Smalley wrote:
> On 07/08/2016 12:19 PM, Vivek Goyal wrote:
> > Provide a security hook to label new file correctly when a file is copied
> > up from lower layer to upper layer of a overlay/union mount.
> >
> > This hook can prepare a new set of creds which are suitable for new file
> > creation during copy up. Caller will use new creds to create file and then
> > revert back to old creds and release new creds.
> >
> > Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
> > ---
> > fs/overlayfs/copy_up.c | 18 ++++++++++++++++++
> > include/linux/lsm_hooks.h | 11 +++++++++++
> > include/linux/security.h | 6 ++++++
> > security/security.c | 8 ++++++++
> > 4 files changed, 43 insertions(+)
> >
> > diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c
> > index 80aa6f1..8ebea18 100644
> > --- a/fs/overlayfs/copy_up.c
> > +++ b/fs/overlayfs/copy_up.c
> > @@ -246,6 +246,8 @@ static int ovl_copy_up_locked(struct dentry *workdir, struct dentry *upperdir,
> > struct dentry *upper = NULL;
> > umode_t mode = stat->mode;
> > int err;
> > + const struct cred *old_creds = NULL;
> > + struct cred *new_creds = NULL;
> >
> > newdentry = ovl_lookup_temp(workdir, dentry);
> > err = PTR_ERR(newdentry);
> > @@ -258,10 +260,26 @@ static int ovl_copy_up_locked(struct dentry *workdir, struct dentry *upperdir,
> > if (IS_ERR(upper))
> > goto out1;
> >
> > + err = security_inode_copy_up(dentry, &new_creds);
> > + if (err < 0) {
> > + if (new_creds)
> > + put_cred(new_creds);
>
> Why do we need a put_cred() here?
Being paranoid for the case of stacked modules. Say first module allocated
creds but second module returned error, in that case creds will have to
be freed.
I can get rid of it for now and if in future two LSMs implement this hook,
one can change it, if need be.
Thanks
Vivek
next prev parent reply other threads:[~2016-07-11 16:54 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-08 16:19 [RFC PATCH 0/7][V2] Overlayfs SELinux Support Vivek Goyal
2016-07-08 16:19 ` [PATCH 1/7] security, overlayfs: provide copy up security hook for unioned files Vivek Goyal
2016-07-11 15:24 ` Stephen Smalley
2016-07-11 16:54 ` Vivek Goyal [this message]
2016-07-08 16:19 ` [PATCH 2/7] selinux: Implementation for inode_copy_up() hook Vivek Goyal
2016-07-08 16:19 ` [PATCH 3/7] security,overlayfs: Provide security hook for copy up of xattrs for overlay file Vivek Goyal
2016-07-08 17:41 ` kbuild test robot
2016-07-11 13:40 ` Vivek Goyal
2016-07-11 13:50 ` [kbuild-all] [PATCH 3/7] security, overlayfs: " Fengguang Wu
2016-07-12 0:02 ` [PATCH 3/7] security,overlayfs: " Stephen Rothwell
2016-07-11 15:31 ` Stephen Smalley
2016-07-11 16:56 ` Vivek Goyal
2016-07-11 17:02 ` Vivek Goyal
2016-07-08 16:19 ` [PATCH 4/7] selinux: Implementation for inode_copy_up_xattr() hook Vivek Goyal
2016-07-08 16:19 ` [PATCH 5/7] selinux: Pass security pointer to determine_inode_label() Vivek Goyal
2016-07-08 16:19 ` [PATCH 6/7] security, overlayfs: Provide hook to correctly label newly created files Vivek Goyal
2016-07-08 16:19 ` [PATCH 7/7] selinux: Implement dentry_create_files_as() hook Vivek Goyal
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