Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Subject: Re: [PATCH 01/12] ima: Have the LSM free its audit rule
To:     Tyler Hicks <tyhicks@linux.microsoft.com>,
        Mimi Zohar <zohar@linux.ibm.com>,
        Dmitry Kasatkin <dmitry.kasatkin@gmail.com>
Cc:     James Morris <jmorris@namei.org>,
        "Serge E . Hallyn" <serge@hallyn.com>,
        Lakshmi Ramasubramanian <nramas@linux.microsoft.com>,
        Prakhar Srivastava <prsriva02@gmail.com>,
        linux-kernel@vger.kernel.org, linux-integrity@vger.kernel.org,
        linux-security-module@vger.kernel.org,
        Janne Karhunen <janne.karhunen@gmail.com>,
        Casey Schaufler <casey@schaufler-ca.com>
References: <20200623003236.830149-1-tyhicks@linux.microsoft.com>
 <20200623003236.830149-2-tyhicks@linux.microsoft.com>
From:   Casey Schaufler <casey@schaufler-ca.com>
Autocrypt: addr=casey@schaufler-ca.com; keydata=
 mQINBFzV9HABEAC/mmv3jeJyF7lR7QhILYg1+PeBLIMZv7KCzBSc/4ZZipoWdmr77Lel/RxQ
 1PrNx0UaM5r6Hj9lJmJ9eg4s/TUBSP67mTx+tsZ1RhG78/WFf9aBe8MSXxY5cu7IUwo0J/CG
 vdSqACKyYPV5eoTJmnMxalu8/oVUHyPnKF3eMGgE0mKOFBUMsb2pLS/enE4QyxhcZ26jeeS6
 3BaqDl1aTXGowM5BHyn7s9LEU38x/y2ffdqBjd3au2YOlvZ+XUkzoclSVfSR29bomZVVyhMB
 h1jTmX4Ac9QjpwsxihT8KNGvOM5CeCjQyWcW/g8LfWTzOVF9lzbx6IfEZDDoDem4+ZiPsAXC
 SWKBKil3npdbgb8MARPes2DpuhVm8yfkJEQQmuLYv8GPiJbwHQVLZGQAPBZSAc7IidD2zbf9
 XAw1/SJGe1poxOMfuSBsfKxv9ba2i8hUR+PH7gWwkMQaQ97B1yXYxVEkpG8Y4MfE5Vd3bjJU
 kvQ/tOBUCw5zwyIRC9+7zr1zYi/3hk+OG8OryZ5kpILBNCo+aePeAJ44znrySarUqS69tuXd
 a3lMPHUJJpUpIwSKQ5UuYYkWlWwENEWSefpakFAIwY4YIBkzoJ/t+XJHE1HTaJnRk6SWpeDf
 CreF3+LouP4njyeLEjVIMzaEpwROsw++BX5i5vTXJB+4UApTAQARAQABtChDYXNleSBTY2hh
 dWZsZXIgPGNhc2V5QHNjaGF1Zmxlci1jYS5jb20+iQJUBBMBCAA+FiEEC+9tH1YyUwIQzUIe
 OKUVfIxDyBEFAlzV9HACGwMFCRLMAwAFCwkIBwIGFQoJCAsCBBYCAwECHgECF4AACgkQOKUV
 fIxDyBG6ag/6AiRl8yof47YOEVHlrmewbpnlBTaYNfJ5cZflNRKRX6t4bp1B2YV1whlDTpiL
 vNOwFkh+ZE0eI5M4x8Gw2Oiok+4Q5liA9PHTozQYF+Ia+qdL5EehfbLGoEBqklpGvG3h8JsO
 7SvONJuFDgvab/U/UriDYycJwzwKZuhVtK9EMpnTtUDyP3DY+Q8h7MWsniNBLVXnh4yBIEJg
 SSgDn3COpZoFTPGKE+rIzioo/GJe8CTa2g+ZggJiY/myWTS3quG0FMvwvNYvZ4I2g6uxSl7n
 bZVqAZgqwoTAv1HSXIAn9muwZUJL03qo25PFi2gQmX15BgJKQcV5RL0GHFHRThDS3IyadOgK
 P2j78P8SddTN73EmsG5OoyzwZAxXfck9A512BfVESqapHurRu2qvMoUkQaW/2yCeRQwGTsFj
 /rr0lnOBkyC6wCmPSKXe3dT2mnD5KnCkjn7KxLqexKt4itGjJz4/ynD/qh+gL7IPbifrQtVH
 JI7cr0fI6Tl8V6efurk5RjtELsAlSR6fKV7hClfeDEgLpigHXGyVOsynXLr59uE+g/+InVic
 jKueTq7LzFd0BiduXGO5HbGyRKw4MG5DNQvC//85EWmFUnDlD3WHz7Hicg95D+2IjD2ZVXJy
 x3LTfKWdC8bU8am1fi+d6tVEFAe/KbUfe+stXkgmfB7pxqW5Ag0EXNX0cAEQAPIEYtPebJzT
 wHpKLu1/j4jQcke06Kmu5RNuj1pEje7kX5IKzQSs+CPH0NbSNGvrA4dNGcuDUTNHgb5Be9hF
 zVqRCEvF2j7BFbrGe9jqMBWHuWheQM8RRoa2UMwQ704mRvKr4sNPh01nKT52ASbWpBPYG3/t
 WbYaqfgtRmCxBnqdOx5mBJIBh9Q38i63DjQgdNcsTx2qS7HFuFyNef5LCf3jogcbmZGxG/b7
 yF4OwmGsVc8ufvlKo5A9Wm+tnRjLr/9Mn9vl5Xa/tQDoPxz26+aWz7j1in7UFzAarcvqzsdM
 Em6S7uT+qy5jcqyuipuenDKYF/yNOVSNnsiFyQTFqCPCpFihOnuaWqfmdeUOQHCSo8fD4aRF
 emsuxqcsq0Jp2ODq73DOTsdFxX2ESXYoFt3Oy7QmIxeEgiHBzdKU2bruIB5OVaZ4zWF+jusM
 Uh+jh+44w9DZkDNjxRAA5CxPlmBIn1OOYt1tsphrHg1cH1fDLK/pDjsJZkiH8EIjhckOtGSb
 aoUUMMJ85nVhN1EbU/A3DkWCVFEA//Vu1+BckbSbJKE7Hl6WdW19BXOZ7v3jo1q6lWwcFYth
 esJfk3ZPPJXuBokrFH8kqnEQ9W2QgrjDX3et2WwZFLOoOCItWxT0/1QO4ikcef/E7HXQf/ij
 Dxf9HG2o5hOlMIAkJq/uLNMvABEBAAGJAjwEGAEIACYWIQQL720fVjJTAhDNQh44pRV8jEPI
 EQUCXNX0cAIbDAUJEswDAAAKCRA4pRV8jEPIEWkzEACKFUnpp+wIVHpckMfBqN8BE5dUbWJc
 GyQ7wXWajLtlPdw1nNw0Wrv+ob2RCT7qQlUo6GRLcvj9Fn5tR4hBvR6D3m8aR0AGHbcC62cq
 I7LjaSDP5j/em4oVL2SMgNTrXgE2w33JMGjAx9oBzkxmKUqprhJomPwmfDHMJ0t7y39Da724
 oLPTkQDpJL1kuraM9TC5NyLe1+MyIxqM/8NujoJbWeQUgGjn9uxQAil7o/xSCjrWCP3kZDID
 vd5ZaHpdl8e1mTExQoKr4EWgaMjmD/a3hZ/j3KfTVNpM2cLfD/QwTMaC2fkK8ExMsz+rUl1H
 icmcmpptCwOSgwSpPY1Zfio6HvEJp7gmDwMgozMfwQuT9oxyFTxn1X3rn1IoYQF3P8gsziY5
 qtTxy2RrgqQFm/hr8gM78RhP54UPltIE96VywviFzDZehMvuwzW//fxysIoK97Y/KBZZOQs+
 /T+Bw80Pwk/dqQ8UmIt2ffHEgwCTbkSm711BejapWCfklxkMZDp16mkxSt2qZovboVjXnfuq
 wQ1QL4o4t1hviM7LyoflsCLnQFJh6RSBhBpKQinMJl/z0A6NYDkQi6vEGMDBWX/M2vk9Jvwa
 v0cEBfY3Z5oFgkh7BUORsu1V+Hn0fR/Lqq/Pyq+nTR26WzGDkolLsDr3IH0TiAVH5ZuPxyz6
 abzjfg==
Message-ID: <277dd210-c443-c067-e731-44ac53418fa5@schaufler-ca.com>
Date:   Mon, 22 Jun 2020 17:55:59 -0700
User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101
 Thunderbird/68.9.0
MIME-Version: 1.0
In-Reply-To: <20200623003236.830149-2-tyhicks@linux.microsoft.com>
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: quoted-printable
Content-Language: en-US
Content-Length: 2662
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On 6/22/2020 5:32 PM, Tyler Hicks wrote:
> Ask the LSM to free its audit rule rather than directly calling kfree()=
=2E
> Both AppArmor and SELinux do additional work in their audit_rule_free()=

> hooks. Fix memory leaks by allowing the LSMs to perform necessary work.=

>
> Fixes: b16942455193 ("ima: use the lsm policy update notifier")
> Signed-off-by: Tyler Hicks <tyhicks@linux.microsoft.com>
> Cc: Janne Karhunen <janne.karhunen@gmail.com>
> ---
>  security/integrity/ima/ima.h        | 6 ++++++
>  security/integrity/ima/ima_policy.c | 2 +-
>  2 files changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.=
h
> index df93ac258e01..de05d7f1d3ec 100644
> --- a/security/integrity/ima/ima.h
> +++ b/security/integrity/ima/ima.h
> @@ -404,6 +404,7 @@ static inline void ima_free_modsig(struct modsig *m=
odsig)
>  #ifdef CONFIG_IMA_LSM_RULES
> =20
>  #define security_filter_rule_init security_audit_rule_init
> +#define security_filter_rule_free security_audit_rule_free
>  #define security_filter_rule_match security_audit_rule_match

In context this seems perfectly reasonable. If, however, you're
working with the LSM infrastructure this set of #defines is maddening.
The existing ones have been driving my nuts for the past few years,
so I'd like to discourage adding another. Since the security_filter_rule
functions are IMA specific they shouldn't be prefixed security_. I know
that it seems to be code churn/bikesheading, but we please change these:

static inline int ima_filter_rule_init(.....)
{
	return security_audit_rule_init(.....);
}

and so forth. I understand if you don't want to make the change.
I have plenty of other things driving me crazy just now, so this
doesn't seem likely to push me over the edge.

> =20
>  #else
> @@ -414,6 +415,11 @@ static inline int security_filter_rule_init(u32 fi=
eld, u32 op, char *rulestr,
>  	return -EINVAL;
>  }
> =20
> +static inline void security_filter_rule_free(void *lsmrule)
> +{
> +	return -EINVAL;
> +}
> +
>  static inline int security_filter_rule_match(u32 secid, u32 field, u32=
 op,
>  					     void *lsmrule)
>  {
> diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/i=
ma/ima_policy.c
> index e493063a3c34..236a731492d1 100644
> --- a/security/integrity/ima/ima_policy.c
> +++ b/security/integrity/ima/ima_policy.c
> @@ -258,7 +258,7 @@ static void ima_lsm_free_rule(struct ima_rule_entry=
 *entry)
>  	int i;
> =20
>  	for (i =3D 0; i < MAX_LSM_RULES; i++) {
> -		kfree(entry->lsm[i].rule);
> +		security_filter_rule_free(entry->lsm[i].rule);
>  		kfree(entry->lsm[i].args_p);
>  	}
>  	kfree(entry);