net: Don't export sysctls to unprivileged users

In preparation for supporting the creation of network namespaces
by unprivileged users, modify all of the per net sysctl exports
and refuse to allow them to unprivileged users.

This makes it safe for unprivileged users in general to access
per net sysctls, and allows sysctls to be exported to unprivileged
users on an individual basis as they are deemed safe.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

9 files changed, 40 insertions, 3 deletions

diff --git a/net/netfilter/ipvs/ip_vs_ctl.c b/net/netfilter/ipvs/ip_vs_ctl.c
index c4ee437..c6cebd5 100644
--- a/net/netfilter/ipvs/ip_vs_ctl.c
+++ b/net/netfilter/ipvs/ip_vs_ctl.c
@@ -3699,6 +3699,10 @@ static int __net_init ip_vs_control_net_init_sysctl(struct net *net)
 		tbl = kmemdup(vs_vars, sizeof(vs_vars), GFP_KERNEL);
 		if (tbl == NULL)
 			return -ENOMEM;
+
+		/* Don't export sysctls to unprivileged users */
+		if (net->user_ns != &init_user_ns)
+			tbl[0].procname = NULL;
 	} else
 		tbl = vs_vars;
 	/* Initialize sysctl defaults */
diff --git a/net/netfilter/ipvs/ip_vs_lblc.c b/net/netfilter/ipvs/ip_vs_lblc.c
index cbd3748..d742aa9 100644
--- a/net/netfilter/ipvs/ip_vs_lblc.c
+++ b/net/netfilter/ipvs/ip_vs_lblc.c
@@ -560,6 +560,11 @@ static int __net_init __ip_vs_lblc_init(struct net *net)
 						GFP_KERNEL);
 		if (ipvs->lblc_ctl_table == NULL)
 			return -ENOMEM;
+
+		/* Don't export sysctls to unprivileged users */
+		if (net->user_ns != &init_user_ns)
+			ipvs->lblc_ctl_table[0].procname = NULL;
+
 	} else
 		ipvs->lblc_ctl_table = vs_vars_table;
 	ipvs->sysctl_lblc_expiration = DEFAULT_EXPIRATION;
@@ -569,7 +574,7 @@ static int __net_init __ip_vs_lblc_init(struct net *net)
 		register_net_sysctl(net, "net/ipv4/vs", ipvs->lblc_ctl_table);
 	if (!ipvs->lblc_ctl_header) {
 		if (!net_eq(net, &init_net))
-			kfree(ipvs->lblc_ctl_table);
+			kfree(ipvs->lblc_ctl_table);\
 		return -ENOMEM;
 	}
 
diff --git a/net/netfilter/ipvs/ip_vs_lblcr.c b/net/netfilter/ipvs/ip_vs_lblcr.c
index 161b679..c03b6a3 100644
--- a/net/netfilter/ipvs/ip_vs_lblcr.c
+++ b/net/netfilter/ipvs/ip_vs_lblcr.c
@@ -754,6 +754,10 @@ static int __net_init __ip_vs_lblcr_init(struct net *net)
 						GFP_KERNEL);
 		if (ipvs->lblcr_ctl_table == NULL)
 			return -ENOMEM;
+
+		/* Don't export sysctls to unprivileged users */
+		if (net->user_ns != &init_user_ns)
+			ipvs->lblcr_ctl_table[0].procname = NULL;
 	} else
 		ipvs->lblcr_ctl_table = vs_vars_table;
 	ipvs->sysctl_lblcr_expiration = DEFAULT_EXPIRATION;
diff --git a/net/netfilter/nf_conntrack_acct.c b/net/netfilter/nf_conntrack_acct.c
index d61e078..7df424e 100644
--- a/net/netfilter/nf_conntrack_acct.c
+++ b/net/netfilter/nf_conntrack_acct.c
@@ -69,6 +69,10 @@ static int nf_conntrack_acct_init_sysctl(struct net *net)
 
 	table[0].data = &net->ct.sysctl_acct;
 
+	/* Don't export sysctls to unprivileged users */
+	if (net->user_ns != &init_user_ns)
+		table[0].procname = NULL;
+
 	net->ct.acct_sysctl_header = register_net_sysctl(net, "net/netfilter",
 							 table);
 	if (!net->ct.acct_sysctl_header) {
diff --git a/net/netfilter/nf_conntrack_ecache.c b/net/netfilter/nf_conntrack_ecache.c
index de9781b..faa978f 100644
--- a/net/netfilter/nf_conntrack_ecache.c
+++ b/net/netfilter/nf_conntrack_ecache.c
@@ -196,6 +196,10 @@ static int nf_conntrack_event_init_sysctl(struct net *net)
 	table[0].data = &net->ct.sysctl_events;
 	table[1].data = &net->ct.sysctl_events_retry_timeout;
 
+	/* Don't export sysctls to unprivileged users */
+	if (net->user_ns != &init_user_ns)
+		table[0].procname = NULL;
+
 	net->ct.event_sysctl_header =
 		register_net_sysctl(net, "net/netfilter", table);
 	if (!net->ct.event_sysctl_header) {
diff --git a/net/netfilter/nf_conntrack_helper.c b/net/netfilter/nf_conntrack_helper.c
index c4bc637..884f2b3 100644
--- a/net/netfilter/nf_conntrack_helper.c
+++ b/net/netfilter/nf_conntrack_helper.c
@@ -64,6 +64,10 @@ static int nf_conntrack_helper_init_sysctl(struct net *net)
 
 	table[0].data = &net->ct.sysctl_auto_assign_helper;
 
+	/* Don't export sysctls to unprivileged users */
+	if (net->user_ns != &init_user_ns)
+		table[0].procname = NULL;
+
 	net->ct.helper_sysctl_header =
 		register_net_sysctl(net, "net/netfilter", table);
 
diff --git a/net/netfilter/nf_conntrack_proto_dccp.c b/net/netfilter/nf_conntrack_proto_dccp.c
index 6535326..a8ae287 100644
--- a/net/netfilter/nf_conntrack_proto_dccp.c
+++ b/net/netfilter/nf_conntrack_proto_dccp.c
@@ -815,7 +815,7 @@ static struct ctl_table dccp_sysctl_table[] = {
 };
 #endif /* CONFIG_SYSCTL */
 
-static int dccp_kmemdup_sysctl_table(struct nf_proto_net *pn,
+static int dccp_kmemdup_sysctl_table(struct net *net, struct nf_proto_net *pn,
 				     struct dccp_net *dn)
 {
 #ifdef CONFIG_SYSCTL
@@ -836,6 +836,10 @@ static int dccp_kmemdup_sysctl_table(struct nf_proto_net *pn,
 	pn->ctl_table[5].data = &dn->dccp_timeout[CT_DCCP_CLOSING];
 	pn->ctl_table[6].data = &dn->dccp_timeout[CT_DCCP_TIMEWAIT];
 	pn->ctl_table[7].data = &dn->dccp_loose;
+
+	/* Don't export sysctls to unprivileged users */
+	if (net->user_ns != &init_user_ns)
+		pn->ctl_table[0].procname = NULL;
 #endif
 	return 0;
 }
@@ -857,7 +861,7 @@ static int dccp_init_net(struct net *net, u_int16_t proto)
 		dn->dccp_timeout[CT_DCCP_TIMEWAIT]	= 2 * DCCP_MSL;
 	}
 
-	return dccp_kmemdup_sysctl_table(pn, dn);
+	return dccp_kmemdup_sysctl_table(net, pn, dn);
 }
 
 static struct nf_conntrack_l4proto dccp_proto4 __read_mostly = {
diff --git a/net/netfilter/nf_conntrack_standalone.c b/net/netfilter/nf_conntrack_standalone.c
index 9b39432..363285d 100644
--- a/net/netfilter/nf_conntrack_standalone.c
+++ b/net/netfilter/nf_conntrack_standalone.c
@@ -489,6 +489,10 @@ static int nf_conntrack_standalone_init_sysctl(struct net *net)
 	table[3].data = &net->ct.sysctl_checksum;
 	table[4].data = &net->ct.sysctl_log_invalid;
 
+	/* Don't export sysctls to unprivileged users */
+	if (net->user_ns != &init_user_ns)
+		table[0].procname = NULL;
+
 	net->ct.sysctl_header = register_net_sysctl(net, "net/netfilter", table);
 	if (!net->ct.sysctl_header)
 		goto out_unregister_netfilter;
diff --git a/net/netfilter/nf_conntrack_timestamp.c b/net/netfilter/nf_conntrack_timestamp.c
index dbb364f..7ea8026 100644
--- a/net/netfilter/nf_conntrack_timestamp.c
+++ b/net/netfilter/nf_conntrack_timestamp.c
@@ -51,6 +51,10 @@ static int nf_conntrack_tstamp_init_sysctl(struct net *net)
 
 	table[0].data = &net->ct.sysctl_tstamp;
 
+	/* Don't export sysctls to unprivileged users */
+	if (net->user_ns != &init_user_ns)
+		table[0].procname = NULL;
+
 	net->ct.tstamp_sysctl_header = register_net_sysctl(net,	"net/netfilter",
 							   table);
 	if (!net->ct.tstamp_sysctl_header) {