[NETFILTER] nfnetlink: unconditionally require CAP_NET_ADMIN

This patch unconditionally requires CAP_NET_ADMIN for all nfnetlink
messages.  It also removes the per-message cap_required field, since all
existing subsystems use CAP_NET_ADMIN for all their messages anyway.

Patrick McHardy owes me a beer if we ever need to re-introduce this.

Signed-off-by: Harald Welte <laforge@netfilter.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/netfilter/nfnetlink.h

@@ -112,7 +112,6 @@ struct nfnl_callback
 {
 	int (*call)(struct sock *nl, struct sk_buff *skb, 
 		struct nlmsghdr *nlh, struct nfattr *cda[], int *errp);
-	kernel_cap_t cap_required; /* capabilities required for this msg */
 	u_int16_t attr_count;	/* number of nfattr's */
 };
 

net/ipv4/netfilter/ip_conntrack_netlink.c

@@ -1543,29 +1543,22 @@ static struct notifier_block ctnl_notifier_exp = {
 
 static struct nfnl_callback ctnl_cb[IPCTNL_MSG_MAX] = {
 	[IPCTNL_MSG_CT_NEW]		= { .call = ctnetlink_new_conntrack,
-					    .attr_count = CTA_MAX,
-					    .cap_required = CAP_NET_ADMIN },
+					    .attr_count = CTA_MAX, },
 	[IPCTNL_MSG_CT_GET] 		= { .call = ctnetlink_get_conntrack,
-					    .attr_count = CTA_MAX,
-					    .cap_required = CAP_NET_ADMIN },
+					    .attr_count = CTA_MAX, },
 	[IPCTNL_MSG_CT_DELETE]  	= { .call = ctnetlink_del_conntrack,
-					    .attr_count = CTA_MAX,
-					    .cap_required = CAP_NET_ADMIN },
+					    .attr_count = CTA_MAX, },
 	[IPCTNL_MSG_CT_GET_CTRZERO] 	= { .call = ctnetlink_get_conntrack,
-					    .attr_count = CTA_MAX,
-					    .cap_required = CAP_NET_ADMIN },
+					    .attr_count = CTA_MAX, },
 };
 
 static struct nfnl_callback ctnl_exp_cb[IPCTNL_MSG_EXP_MAX] = {
 	[IPCTNL_MSG_EXP_GET]		= { .call = ctnetlink_get_expect,
-					    .attr_count = CTA_EXPECT_MAX,
-					    .cap_required = CAP_NET_ADMIN },
+					    .attr_count = CTA_EXPECT_MAX, },
 	[IPCTNL_MSG_EXP_NEW]		= { .call = ctnetlink_new_expect,
-					    .attr_count = CTA_EXPECT_MAX,
-					    .cap_required = CAP_NET_ADMIN },
+					    .attr_count = CTA_EXPECT_MAX, },
 	[IPCTNL_MSG_EXP_DELETE]		= { .call = ctnetlink_del_expect,
-					    .attr_count = CTA_EXPECT_MAX,
-					    .cap_required = CAP_NET_ADMIN },
+					    .attr_count = CTA_EXPECT_MAX, },
 };
 
 static struct nfnetlink_subsystem ctnl_subsys = {

net/netfilter/nfnetlink.c

@@ -223,6 +223,12 @@ static inline int nfnetlink_rcv_msg(struct sk_buff *skb,
 		 NFNL_SUBSYS_ID(nlh->nlmsg_type),
 		 NFNL_MSG_TYPE(nlh->nlmsg_type));
 
+	if (!cap_raised(NETLINK_CB(skb).eff_cap, CAP_NET_ADMIN)) {
+		DEBUGP("missing CAP_NET_ADMIN\n");
+		*errp = -EPERM;
+		return -1;
+	}
+
 	/* Only requests are handled by kernel now. */
 	if (!(nlh->nlmsg_flags & NLM_F_REQUEST)) {
 		DEBUGP("received non-request message\n");
@@ -240,15 +246,12 @@ static inline int nfnetlink_rcv_msg(struct sk_buff *skb,
 	ss = nfnetlink_get_subsys(type);
 	if (!ss) {
 #ifdef CONFIG_KMOD
-		if (cap_raised(NETLINK_CB(skb).eff_cap, CAP_NET_ADMIN)) {
-			/* don't call nfnl_shunlock, since it would reenter
-			 * with further packet processing */
-			up(&nfnl_sem);
-			request_module("nfnetlink-subsys-%d",
-					NFNL_SUBSYS_ID(type));
-			nfnl_shlock();
-			ss = nfnetlink_get_subsys(type);
-		}
+		/* don't call nfnl_shunlock, since it would reenter
+		 * with further packet processing */
+		up(&nfnl_sem);
+		request_module("nfnetlink-subsys-%d", NFNL_SUBSYS_ID(type));
+		nfnl_shlock();
+		ss = nfnetlink_get_subsys(type);
 		if (!ss)
 #endif
 			goto err_inval;
@@ -260,13 +263,6 @@ static inline int nfnetlink_rcv_msg(struct sk_buff *skb,
 		goto err_inval;
 	}
 
-	if (nc->cap_required && 
-	    !cap_raised(NETLINK_CB(skb).eff_cap, nc->cap_required)) {
-		DEBUGP("permission denied for type %d\n", type);
-		*errp = -EPERM;
-		return -1;
-	}
-
 	{
 		u_int16_t attr_count = 
 			ss->cb[NFNL_MSG_TYPE(nlh->nlmsg_type)].attr_count;

net/netfilter/nfnetlink_log.c

@@ -862,11 +862,9 @@ out_put:
 
 static struct nfnl_callback nfulnl_cb[NFULNL_MSG_MAX] = {
 	[NFULNL_MSG_PACKET]	= { .call = nfulnl_recv_unsupp,
-				    .attr_count = NFULA_MAX,
-				    .cap_required = CAP_NET_ADMIN, },
+				    .attr_count = NFULA_MAX, },
 	[NFULNL_MSG_CONFIG]	= { .call = nfulnl_recv_config,
-				    .attr_count = NFULA_CFG_MAX,
-				    .cap_required = CAP_NET_ADMIN },
+				    .attr_count = NFULA_CFG_MAX, },
 };
 
 static struct nfnetlink_subsystem nfulnl_subsys = {

net/netfilter/nfnetlink_queue.c

@@ -931,14 +931,11 @@ out_put:
 
 static struct nfnl_callback nfqnl_cb[NFQNL_MSG_MAX] = {
 	[NFQNL_MSG_PACKET]	= { .call = nfqnl_recv_unsupp,
-				    .attr_count = NFQA_MAX,
-				    .cap_required = CAP_NET_ADMIN },
+				    .attr_count = NFQA_MAX, },
 	[NFQNL_MSG_VERDICT]	= { .call = nfqnl_recv_verdict,
-				    .attr_count = NFQA_MAX,
-				    .cap_required = CAP_NET_ADMIN },
+				    .attr_count = NFQA_MAX, },
 	[NFQNL_MSG_CONFIG]	= { .call = nfqnl_recv_config,
-				    .attr_count = NFQA_CFG_MAX,
-				    .cap_required = CAP_NET_ADMIN },
+				    .attr_count = NFQA_CFG_MAX, },
 };
 
 static struct nfnetlink_subsystem nfqnl_subsys = {