linux-kernel - Re: [PATCH 15/28] security: Introduce inode_post

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Message-ID: <92c36707c8f9398f7f626c3da01bb98586880836.camel@huaweicloud.com>
Date:   Thu, 09 Mar 2023 14:07:26 +0100
From:   Roberto Sassu <roberto.sassu@...weicloud.com>
To:     Mimi Zohar <zohar@...ux.ibm.com>, viro@...iv.linux.org.uk,
        chuck.lever@...cle.com, jlayton@...nel.org,
        dmitry.kasatkin@...il.com, paul@...l-moore.com, jmorris@...ei.org,
        serge@...lyn.com, dhowells@...hat.com, jarkko@...nel.org,
        stephen.smalley.work@...il.com, eparis@...isplace.org,
        casey@...aufler-ca.com, brauner@...nel.org
Cc:     linux-fsdevel@...r.kernel.org, linux-nfs@...r.kernel.org,
        linux-integrity@...r.kernel.org,
        linux-security-module@...r.kernel.org, keyrings@...r.kernel.org,
        selinux@...r.kernel.org, linux-kernel@...r.kernel.org,
        stefanb@...ux.ibm.com, Roberto Sassu <roberto.sassu@...wei.com>
Subject: Re: [PATCH 15/28] security: Introduce inode_post_removexattr hook

On Wed, 2023-03-08 at 10:43 -0500, Mimi Zohar wrote:
> Hi Roberto,
> 
> On Fri, 2023-03-03 at 19:18 +0100, Roberto Sassu wrote:
> > From: Roberto Sassu <roberto.sassu@...wei.com>
> > 
> > In preparation for moving IMA and EVM to the LSM infrastructure, introduce
> > the inode_post_removexattr hook.
> > 
> > Signed-off-by: Roberto Sassu <roberto.sassu@...wei.com>
> > ---
> >  fs/xattr.c                    |  1 +
> >  include/linux/lsm_hook_defs.h |  2 ++
> >  include/linux/security.h      |  5 +++++
> >  security/security.c           | 14 ++++++++++++++
> >  4 files changed, 22 insertions(+)
> > 
> > diff --git a/fs/xattr.c b/fs/xattr.c
> > index 14a7eb3c8fa..10c959d9fc6 100644
> > --- a/fs/xattr.c
> > +++ b/fs/xattr.c
> > @@ -534,6 +534,7 @@ __vfs_removexattr_locked(struct mnt_idmap *idmap,
> >  
> >  	if (!error) {
> >  		fsnotify_xattr(dentry);
> > +		security_inode_post_removexattr(dentry, name);
> >  		evm_inode_post_removexattr(dentry, name);
> >  	}
> 
> Nothing wrong with this, but other places in this function test "if
> (error) goto ...".   Perhaps it is time to clean this up.

Theoretically, all 'goto out' can be replaced with 'return error'.

I would be more in favor of minimizing the changes as much as possible
to reach the main goal. But it is ok also to change the last part.

Thanks

Roberto

> >  
> > diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
> > index eedefbcdde3..2ae5224d967 100644
> > --- a/include/linux/lsm_hook_defs.h
> > +++ b/include/linux/lsm_hook_defs.h
> > @@ -147,6 +147,8 @@ LSM_HOOK(int, 0, inode_getxattr, struct dentry *dentry, const char *name)
> >  LSM_HOOK(int, 0, inode_listxattr, struct dentry *dentry)
> >  LSM_HOOK(int, 0, inode_removexattr, struct mnt_idmap *idmap,
> >  	 struct dentry *dentry, const char *name)
> > +LSM_HOOK(void, LSM_RET_VOID, inode_post_removexattr, struct dentry *dentry,
> > +	 const char *name)
> 
> @Christian should the security_inode_removexattr() and
> security_inode_post_removexattr() arguments be the same?
> 
> >  LSM_HOOK(int, 0, inode_set_acl, struct mnt_idmap *idmap,
> >  	 struct dentry *dentry, const char *acl_name, struct posix_acl *kacl)
> >  LSM_HOOK(int, 0, inode_get_acl, struct mnt_idmap *idmap,