linux-hardening - Re: [PATCH 5/9] LSM: Introduce inode_post

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Message-ID: <20221018145013.duwxiczk5gj7pk66@wittgenstein>
Date:   Tue, 18 Oct 2022 16:50:13 +0200
From:   Christian Brauner <brauner@...nel.org>
To:     Kees Cook <keescook@...omium.org>
Cc:     Mimi Zohar <zohar@...ux.ibm.com>,
        Dmitry Kasatkin <dmitry.kasatkin@...il.com>,
        Paul Moore <paul@...l-moore.com>,
        James Morris <jmorris@...ei.org>,
        "Serge E. Hallyn" <serge@...lyn.com>, Takashi Iwai <tiwai@...e.de>,
        Jonathan McDowell <noodles@...com>,
        Casey Schaufler <casey@...aufler-ca.com>,
        linux-integrity@...r.kernel.org,
        linux-security-module@...r.kernel.org,
        Mickaël Salaün <mic@...ikod.net>,
        KP Singh <kpsingh@...nel.org>,
        John Johansen <john.johansen@...onical.com>,
        linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org,
        fsdevel@...r.kernel.org
Subject: Re: [PATCH 5/9] LSM: Introduce inode_post_setattr hook

On Thu, Oct 13, 2022 at 03:36:50PM -0700, Kees Cook wrote:
> IMA and EVM need to hook after setattr finishes. Introduce this hook and
> move IMA and EVM's open-coded stacking to use it.
> 
> Cc: Mimi Zohar <zohar@...ux.ibm.com>
> Cc: Dmitry Kasatkin <dmitry.kasatkin@...il.com>
> Cc: Paul Moore <paul@...l-moore.com>
> Cc: James Morris <jmorris@...ei.org>
> Cc: "Serge E. Hallyn" <serge@...lyn.com>
> Cc: Takashi Iwai <tiwai@...e.de>
> Cc: Jonathan McDowell <noodles@...com>
> Cc: Casey Schaufler <casey@...aufler-ca.com>
> Cc: linux-integrity@...r.kernel.org
> Cc: linux-security-module@...r.kernel.org
> Signed-off-by: Kees Cook <keescook@...omium.org>
> ---
>  fs/attr.c                             |  3 +--
>  include/linux/evm.h                   |  6 ------
>  include/linux/ima.h                   |  9 ---------
>  include/linux/lsm_hook_defs.h         |  3 +++
>  security/integrity/evm/evm_main.c     | 10 +++++++++-
>  security/integrity/ima/ima.h          |  2 ++
>  security/integrity/ima/ima_appraise.c |  2 +-
>  security/integrity/ima/ima_main.c     |  1 +
>  security/security.c                   |  8 ++++++++
>  9 files changed, 25 insertions(+), 19 deletions(-)
> 
> diff --git a/fs/attr.c b/fs/attr.c
> index 1552a5f23d6b..e5731057426b 100644
> --- a/fs/attr.c
> +++ b/fs/attr.c
> @@ -423,8 +423,7 @@ int notify_change(struct user_namespace *mnt_userns, struct dentry *dentry,
>  
>  	if (!error) {
>  		fsnotify_change(dentry, ia_valid);
> -		ima_inode_post_setattr(mnt_userns, dentry);
> -		evm_inode_post_setattr(dentry, ia_valid);
> +		security_inode_post_setattr(mnt_userns, dentry, ia_valid);

I like that change. In general, no more separate evm_* and ima_*
invocations in the vfs would be much appreciated.