[PATCH v27 18/25] LSM: security_secid_to_secctx in netlink netfilter

STALE1935d REVIEWED: 5 (3M)

From: Casey Schaufler <casey@schaufler-ca.com>
Date: 2021-06-11 00:24:45
Also in: linux-security-module, lkml, netfilter-devel, selinux
Subsystem: netfilter, networking [general], the rest · Maintainers: Pablo Neira Ayuso, Florian Westphal, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds

Revision v27 of 45 in this series; 4 review trailers (1 from subsystem maintainers).

Revisions (45)

2019-04-09 v1 [diff vs current]
2019-04-09 v1 [diff vs current]
2019-04-09 v1 [diff vs current]
2019-05-31 v1 [diff vs current]
2019-06-02 v1 [diff vs current]
2019-06-18 v2 [diff vs current]
2019-06-21 v3 [diff vs current]
2019-06-24 v3 [diff vs current]
2019-06-26 v4 [diff vs current]
2019-07-03 v5 [diff vs current]
2019-07-26 v5 [diff vs current]
2019-08-07 v7 [diff vs current]
2019-08-29 v8 [diff vs current]
2019-10-24 v10 [diff vs current]
2019-11-13 v10 [diff vs current]
2019-11-13 v11 [diff vs current]
2019-11-19 v11 [diff vs current]
2019-11-27 v11 [diff vs current]
2019-12-16 v12 [diff vs current]
2019-12-16 v12 [diff vs current]
2019-12-24 v12 [diff vs current]
2019-12-25 v13 [diff vs current]
2020-01-24 v14 [diff vs current]
2020-02-14 v15 [diff vs current]
2020-04-07 v16 [diff vs current]
2020-05-14 v17 [diff vs current]
2020-10-12 v21 [diff vs current]
2020-11-05 v22 [diff vs current]
2020-11-20 v22 [diff vs current]
2021-01-27 v24 [diff vs current]
2021-03-09 v25 [diff vs current]
2021-05-13 v26 [diff vs current]
2021-06-11 v27 current
2021-07-22 v28 [diff vs current]
2021-09-24 v29 [diff vs current]
2021-11-24 v30 [diff vs current]
2021-12-14 v31 [diff vs current]
2022-02-03 v32 [diff vs current]
2022-03-10 v33 [diff vs current]
2022-04-07 v34 [diff vs current]
2022-04-15 v34 [diff vs current]
2022-04-18 v35 [diff vs current]
2022-06-09 v36 [diff vs current]
2022-06-28 v37 [diff vs current]
2022-09-27 v38 [diff vs current]

Change netlink netfilter interfaces to use lsmcontext
pointers, and remove scaffolding.

Reviewed-by: Kees Cook <redacted>
Reviewed-by: John Johansen <john.johansen@canonical.com>
Acked-by: Stephen Smalley <redacted>
Acked-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Cc: netdev@vger.kernel.org
Cc: netfilter-devel@vger.kernel.org
---
 net/netfilter/nfnetlink_queue.c | 37 +++++++++++++--------------------
 1 file changed, 14 insertions(+), 23 deletions(-)

diff --git a/net/netfilter/nfnetlink_queue.c b/net/netfilter/nfnetlink_queue.c
index 719ec0f0f2ab..bf8db099090b 100644
--- a/net/netfilter/nfnetlink_queue.c
+++ b/net/netfilter/nfnetlink_queue.c

@@ -301,15 +301,13 @@ 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 void 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;
+		return;
 
 	read_lock_bh(&skb->sk->sk_callback_lock);

@@ -318,14 +316,12 @@ 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;
 #endif
-	return seclen;
+	return;
 }
 
 static u32 nfqnl_get_bridge_size(struct nf_queue_entry *entry)

@@ -397,12 +393,10 @@ nfqnl_build_packet_message(struct net *net, struct nfqnl_instance *queue,
 	struct net_device *indev;
 	struct net_device *outdev;
 	struct nf_conn *ct = NULL;
+	struct lsmcontext context = { };
 	enum ip_conntrack_info ctinfo;
 	struct nfnl_ct_hook *nfnl_ct;
 	bool csum_verify;
-	struct lsmcontext scaff; /* scaffolding */
-	char *secdata = NULL;
-	u32 seclen = 0;
 
 	size = nlmsg_total_size(sizeof(struct nfgenmsg))
 		+ nla_total_size(sizeof(struct nfqnl_msg_packet_hdr))

@@ -470,9 +464,9 @@ 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);
-		if (seclen)
-			size += nla_total_size(seclen);
+		nfqnl_get_sk_secctx(entskb, &context);
+		if (context.len)
+			size += nla_total_size(context.len);
 	}
 
 	skb = alloc_skb(size, GFP_ATOMIC);

@@ -602,7 +596,8 @@ 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 (context.len &&
+	    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)

@@ -630,10 +625,8 @@ 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 (context.len)
+		security_release_secctx(&context);
 	return skb;
 
 nla_put_failure:

@@ -641,10 +634,8 @@ 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 (context.len)
+		security_release_secctx(&context);
 	return NULL;
 }

-- 
2.29.2

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