diff mbox series

[v20,17/23] LSM: security_secid_to_secctx in netlink netfilter

Message ID 20200826145247.10029-18-casey@schaufler-ca.com
State New
Headers show
Series LSM: Module stacking for AppArmor | expand

Commit Message

Casey Schaufler Aug. 26, 2020, 2:52 p.m. UTC
Change netlink netfilter interfaces to use lsmcontext
pointers, and remove scaffolding.

Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: John Johansen <john.johansen@canonical.com>
Acked-by: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
cc: netdev@vger.kernel.org
---
 net/netfilter/nfnetlink_queue.c | 31 ++++++++++++-------------------
 1 file changed, 12 insertions(+), 19 deletions(-)

Comments

Paul Moore Sept. 6, 2020, 3:11 a.m. UTC | #1
On Wed, Aug 26, 2020 at 11:20 AM Casey Schaufler <casey@schaufler-ca.com> wrote:
>
> Change netlink netfilter interfaces to use lsmcontext
> pointers, and remove scaffolding.
>
> Reviewed-by: Kees Cook <keescook@chromium.org>
> Reviewed-by: John Johansen <john.johansen@canonical.com>
> Acked-by: Stephen Smalley <sds@tycho.nsa.gov>
> Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
> cc: netdev@vger.kernel.org
> ---
>  net/netfilter/nfnetlink_queue.c | 31 ++++++++++++-------------------
>  1 file changed, 12 insertions(+), 19 deletions(-)

...

> diff --git a/net/netfilter/nfnetlink_queue.c b/net/netfilter/nfnetlink_queue.c
> index d3f8e808c5d3..c830401f7792 100644
> --- a/net/netfilter/nfnetlink_queue.c
> +++ b/net/netfilter/nfnetlink_queue.c
> @@ -401,8 +399,7 @@ nfqnl_build_packet_message(struct net *net, struct nfqnl_instance *queue,
>         enum ip_conntrack_info ctinfo;
>         struct nfnl_ct_hook *nfnl_ct;
>         bool csum_verify;
> -       struct lsmcontext scaff; /* scaffolding */
> -       char *secdata = NULL;
> +       struct lsmcontext context = { };
>         u32 seclen = 0;
>
>         size = nlmsg_total_size(sizeof(struct nfgenmsg))
> @@ -469,7 +466,7 @@ nfqnl_build_packet_message(struct net *net, struct nfqnl_instance *queue,
>         }
>
>         if ((queue->flags & NFQA_CFG_F_SECCTX) && entskb->sk) {
> -               seclen = nfqnl_get_sk_secctx(entskb, &secdata);
> +               seclen = nfqnl_get_sk_secctx(entskb, &context);
>                 if (seclen)
>                         size += nla_total_size(seclen);
>         }

I think we can get rid of the local "seclen" variable, right?  We can
embed the nfqnl_get_sk_secctx() in the conditional and then simply
reference "context.len" everywhere else, yes?  For example:

  if (nfqnl_get_sk_secctx(..., &context))
    size += nla_total_size(context.len);
Pablo Neira Ayuso Sept. 8, 2020, 10:46 a.m. UTC | #2
On Wed, Aug 26, 2020 at 07:52:41AM -0700, Casey Schaufler wrote:
> Change netlink netfilter interfaces to use lsmcontext
> pointers, and remove scaffolding.
> 
> Reviewed-by: Kees Cook <keescook@chromium.org>
> Reviewed-by: John Johansen <john.johansen@canonical.com>
> Acked-by: Stephen Smalley <sds@tycho.nsa.gov>
> Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
> cc: netdev@vger.kernel.org
> ---
>  net/netfilter/nfnetlink_queue.c | 31 ++++++++++++-------------------
>  1 file changed, 12 insertions(+), 19 deletions(-)
> 
[...]
>  static u32 nfqnl_get_bridge_size(struct nf_queue_entry *entry)
> @@ -401,8 +399,7 @@ nfqnl_build_packet_message(struct net *net, struct nfqnl_instance *queue,
>  	enum ip_conntrack_info ctinfo;
>  	struct nfnl_ct_hook *nfnl_ct;
>  	bool csum_verify;
> -	struct lsmcontext scaff; /* scaffolding */
> -	char *secdata = NULL;
> +	struct lsmcontext context = { };
>  	u32 seclen = 0;

While at it, please introduce reverse xmas tree in variable
definitions incrementally:

	struct lsmcontext context = { };
  	enum ip_conntrack_info ctinfo;
  	struct nfnl_ct_hook *nfnl_ct;
  	bool csum_verify;
 	u32 seclen = 0;

And Cc: netfilter-devel@vger.kernel.org for patches that update the
Netfilter codebase.

Thanks.
diff mbox series

Patch

diff --git a/net/netfilter/nfnetlink_queue.c b/net/netfilter/nfnetlink_queue.c
index d3f8e808c5d3..c830401f7792 100644
--- a/net/netfilter/nfnetlink_queue.c
+++ b/net/netfilter/nfnetlink_queue.c
@@ -301,12 +301,10 @@  static int nfqnl_put_sk_uidgid(struct sk_buff *skb, struct sock *sk)
 	return -1;
 }
 
-static u32 nfqnl_get_sk_secctx(struct sk_buff *skb, char **secdata)
+static u32 nfqnl_get_sk_secctx(struct sk_buff *skb, struct lsmcontext *context)
 {
-	u32 seclen = 0;
 #if IS_ENABLED(CONFIG_NETWORK_SECMARK)
 	struct lsmblob blob;
-	struct lsmcontext context = { };
 
 	if (!skb || !sk_fullsock(skb->sk))
 		return 0;
@@ -318,14 +316,14 @@  static u32 nfqnl_get_sk_secctx(struct sk_buff *skb, char **secdata)
 		 * blob. security_secid_to_secctx() will know which security
 		 * module to use to create the secctx.  */
 		lsmblob_init(&blob, skb->secmark);
-		security_secid_to_secctx(&blob, &context);
-		*secdata = context.context;
+		security_secid_to_secctx(&blob, context);
 	}
 
 	read_unlock_bh(&skb->sk->sk_callback_lock);
-	seclen = context.len;
+	return context->len;
+#else
+	return 0;
 #endif
-	return seclen;
 }
 
 static u32 nfqnl_get_bridge_size(struct nf_queue_entry *entry)
@@ -401,8 +399,7 @@  nfqnl_build_packet_message(struct net *net, struct nfqnl_instance *queue,
 	enum ip_conntrack_info ctinfo;
 	struct nfnl_ct_hook *nfnl_ct;
 	bool csum_verify;
-	struct lsmcontext scaff; /* scaffolding */
-	char *secdata = NULL;
+	struct lsmcontext context = { };
 	u32 seclen = 0;
 
 	size = nlmsg_total_size(sizeof(struct nfgenmsg))
@@ -469,7 +466,7 @@  nfqnl_build_packet_message(struct net *net, struct nfqnl_instance *queue,
 	}
 
 	if ((queue->flags & NFQA_CFG_F_SECCTX) && entskb->sk) {
-		seclen = nfqnl_get_sk_secctx(entskb, &secdata);
+		seclen = nfqnl_get_sk_secctx(entskb, &context);
 		if (seclen)
 			size += nla_total_size(seclen);
 	}
@@ -604,7 +601,7 @@  nfqnl_build_packet_message(struct net *net, struct nfqnl_instance *queue,
 	    nfqnl_put_sk_uidgid(skb, entskb->sk) < 0)
 		goto nla_put_failure;
 
-	if (seclen && nla_put(skb, NFQA_SECCTX, seclen, secdata))
+	if (seclen && nla_put(skb, NFQA_SECCTX, context.len, context.context))
 		goto nla_put_failure;
 
 	if (ct && nfnl_ct->build(skb, ct, ctinfo, NFQA_CT, NFQA_CT_INFO) < 0)
@@ -632,10 +629,8 @@  nfqnl_build_packet_message(struct net *net, struct nfqnl_instance *queue,
 	}
 
 	nlh->nlmsg_len = skb->len;
-	if (seclen) {
-		lsmcontext_init(&scaff, secdata, seclen, 0);
-		security_release_secctx(&scaff);
-	}
+	if (seclen)
+		security_release_secctx(&context);
 	return skb;
 
 nla_put_failure:
@@ -643,10 +638,8 @@  nfqnl_build_packet_message(struct net *net, struct nfqnl_instance *queue,
 	kfree_skb(skb);
 	net_err_ratelimited("nf_queue: error creating packet message\n");
 nlmsg_failure:
-	if (seclen) {
-		lsmcontext_init(&scaff, secdata, seclen, 0);
-		security_release_secctx(&scaff);
-	}
+	if (seclen)
+		security_release_secctx(&context);
 	return NULL;
 }