linux-kernel - Re: [PATCH v2 15/25] security: call evm fscaps hooks from generic security hooks

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Message-ID: <ZdaTPV/Ngd8ed/p5@do-x1extreme>
Date: Wed, 21 Feb 2024 18:20:13 -0600
From: "Seth Forshee (DigitalOcean)" <sforshee@...nel.org>
To: Paul Moore <paul@...l-moore.com>
Cc: Christian Brauner <brauner@...nel.org>, Serge Hallyn <serge@...lyn.com>,
	Eric Paris <eparis@...hat.com>, James Morris <jmorris@...ei.org>,
	Alexander Viro <viro@...iv.linux.org.uk>, Jan Kara <jack@...e.cz>,
	Stephen Smalley <stephen.smalley.work@...il.com>,
	Ondrej Mosnacek <omosnace@...hat.com>,
	Casey Schaufler <casey@...aufler-ca.com>,
	Mimi Zohar <zohar@...ux.ibm.com>,
	Roberto Sassu <roberto.sassu@...wei.com>,
	Dmitry Kasatkin <dmitry.kasatkin@...il.com>,
	Eric Snowberg <eric.snowberg@...cle.com>,
	"Matthew Wilcox (Oracle)" <willy@...radead.org>,
	Jonathan Corbet <corbet@....net>,
	Miklos Szeredi <miklos@...redi.hu>,
	Amir Goldstein <amir73il@...il.com>, linux-kernel@...r.kernel.org,
	linux-fsdevel@...r.kernel.org,
	linux-security-module@...r.kernel.org, audit@...r.kernel.org,
	selinux@...r.kernel.org, linux-integrity@...r.kernel.org,
	linux-doc@...r.kernel.org, linux-unionfs@...r.kernel.org
Subject: Re: [PATCH v2 15/25] security: call evm fscaps hooks from generic
 security hooks

On Wed, Feb 21, 2024 at 06:43:43PM -0500, Paul Moore wrote:
> On Wed, Feb 21, 2024 at 4:25 PM Seth Forshee (DigitalOcean)
> <sforshee@...nel.org> wrote:
> >
> > Signed-off-by: Seth Forshee (DigitalOcean) <sforshee@...nel.org>
> > ---
> >  security/security.c | 15 +++++++++++++--
> >  1 file changed, 13 insertions(+), 2 deletions(-)
> 
> First off, you've got to write *something* for the commit description,
> even if it is just a single sentence.
> 
> > diff --git a/security/security.c b/security/security.c
> > index 0d210da9862c..f515d8430318 100644
> > --- a/security/security.c
> > +++ b/security/security.c
> > @@ -2365,9 +2365,14 @@ int security_inode_remove_acl(struct mnt_idmap *idmap,
> >  int security_inode_set_fscaps(struct mnt_idmap *idmap, struct dentry *dentry,
> >                               const struct vfs_caps *caps, int flags)
> >  {
> > +       int ret;
> > +
> >         if (unlikely(IS_PRIVATE(d_backing_inode(dentry))))
> >                 return 0;
> > -       return call_int_hook(inode_set_fscaps, 0, idmap, dentry, caps, flags);
> > +       ret = call_int_hook(inode_set_fscaps, 0, idmap, dentry, caps, flags);
> > +       if (ret)
> > +               return ret;
> > +       return evm_inode_set_fscaps(idmap, dentry, caps, flags);
> >  }
> >
> >  /**
> > @@ -2387,6 +2392,7 @@ void security_inode_post_set_fscaps(struct mnt_idmap *idmap,
> >         if (unlikely(IS_PRIVATE(d_backing_inode(dentry))))
> >                 return;
> >         call_void_hook(inode_post_set_fscaps, idmap, dentry, caps, flags);
> > +       evm_inode_post_set_fscaps(idmap, dentry, caps, flags);
> >  }
> >
> >  /**
> > @@ -2415,9 +2421,14 @@ int security_inode_get_fscaps(struct mnt_idmap *idmap, struct dentry *dentry)
> >   */
> >  int security_inode_remove_fscaps(struct mnt_idmap *idmap, struct dentry *dentry)
> >  {
> > +       int ret;
> > +
> >         if (unlikely(IS_PRIVATE(d_backing_inode(dentry))))
> >                 return 0;
> > -       return call_int_hook(inode_remove_fscaps, 0, idmap, dentry);
> > +       ret = call_int_hook(inode_remove_fscaps, 0, idmap, dentry);
> > +       if (ret)
> > +               return ret;
> > +       return evm_inode_remove_fscaps(dentry);
> >  }
> 
> If you take a look at linux-next or the LSM tree's dev branch you'll
> see that we've gotten rid of the dedicated IMA and EVM hooks,
> promoting both IMA and EVM to "proper" LSMs that leverage the existing
> LSM hook infrastructure.  In this patchset, and moving forward, please
> don't add dedicated IMA/EVM hooks like this, instead register them as
> LSM hook implementations with LSM_HOOK_INIT().

Yeah, I'm aware that work was going on and got applied recently. I've
been assuming this change will go in through the vfs tree though, and I
wasn't sure how you and Al/Christian would want to handle that
dependency between your trees, so I held off on updating based off the
LSM tree. I'm happy to update this for the next round though.

Thanks,
Seth