From e788d29cf3d076b2c89da596fd35e089145c3370 Mon Sep 17 00:00:00 2001
From: "Eric W. Biederman" <ebiederm@xmission.com>
Date: Fri, 16 Nov 2012 03:02:59 +0000
Subject: [PATCH] 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>
---
 net/core/neighbour.c                    | 4 ++++
 net/core/sysctl_net_core.c              | 5 +++++
 net/ipv4/devinet.c                      | 8 ++++++++
 net/ipv4/ip_fragment.c                  | 4 ++++
 net/ipv4/route.c                        | 4 ++++
 net/ipv4/sysctl_net_ipv4.c              | 3 +++
 net/ipv6/addrconf.c                     | 4 ++++
 net/ipv6/icmp.c                         | 7 ++++++-
 net/ipv6/reassembly.c                   | 4 ++++
 net/ipv6/route.c                        | 4 ++++
 net/ipv6/sysctl_net_ipv6.c              | 4 ++++
 net/netfilter/ipvs/ip_vs_ctl.c          | 4 ++++
 net/netfilter/ipvs/ip_vs_lblc.c         | 7 ++++++-
 net/netfilter/ipvs/ip_vs_lblcr.c        | 4 ++++
 net/netfilter/nf_conntrack_acct.c       | 4 ++++
 net/netfilter/nf_conntrack_ecache.c     | 4 ++++
 net/netfilter/nf_conntrack_helper.c     | 4 ++++
 net/netfilter/nf_conntrack_proto_dccp.c | 8 ++++++--
 net/netfilter/nf_conntrack_standalone.c | 4 ++++
 net/netfilter/nf_conntrack_timestamp.c  | 4 ++++
 net/unix/sysctl_net_unix.c              | 4 ++++
 net/xfrm/xfrm_sysctl.c                  | 4 ++++
 22 files changed, 98 insertions(+), 4 deletions(-)

diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index 22571488730a7..f1c0c2e9cad5f 100644
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -2987,6 +2987,10 @@ int neigh_sysctl_register(struct net_device *dev, struct neigh_parms *p,
 		t->neigh_vars[NEIGH_VAR_BASE_REACHABLE_TIME_MS].extra1 = dev;
 	}
 
+	/* Don't export sysctls to unprivileged users */
+	if (neigh_parms_net(p)->user_ns != &init_user_ns)
+		t->neigh_vars[0].procname = NULL;
+
 	snprintf(neigh_path, sizeof(neigh_path), "net/%s/neigh/%s",
 		p_name, dev_name_source);
 	t->sysctl_header =
diff --git a/net/core/sysctl_net_core.c b/net/core/sysctl_net_core.c
index a7c36845b123c..d1b08045a9dfb 100644
--- a/net/core/sysctl_net_core.c
+++ b/net/core/sysctl_net_core.c
@@ -216,6 +216,11 @@ static __net_init int sysctl_core_net_init(struct net *net)
 			goto err_dup;
 
 		tbl[0].data = &net->core.sysctl_somaxconn;
+
+		/* Don't export any sysctls to unprivileged users */
+		if (net->user_ns != &init_user_ns) {
+			tbl[0].procname = NULL;
+		}
 	}
 
 	net->core.sysctl_hdr = register_net_sysctl(net, "net/core", tbl);
diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
index f6db227c1fd92..6e06e924ed995 100644
--- a/net/ipv4/devinet.c
+++ b/net/ipv4/devinet.c
@@ -1815,6 +1815,10 @@ static int __devinet_sysctl_register(struct net *net, char *dev_name,
 		t->devinet_vars[i].extra2 = net;
 	}
 
+	/* Don't export sysctls to unprivileged users */
+	if (net->user_ns != &init_user_ns)
+		t->devinet_vars[0].procname = NULL;
+
 	snprintf(path, sizeof(path), "net/ipv4/conf/%s", dev_name);
 
 	t->sysctl_header = register_net_sysctl(net, path, t->devinet_vars);
@@ -1900,6 +1904,10 @@ static __net_init int devinet_init_net(struct net *net)
 		tbl[0].data = &all->data[IPV4_DEVCONF_FORWARDING - 1];
 		tbl[0].extra1 = all;
 		tbl[0].extra2 = net;
+
+		/* Don't export sysctls to unprivileged users */
+		if (net->user_ns != &init_user_ns)
+			tbl[0].procname = NULL;
 #endif
 	}
 
diff --git a/net/ipv4/ip_fragment.c b/net/ipv4/ip_fragment.c
index 448e685468274..1cf6a768cd53d 100644
--- a/net/ipv4/ip_fragment.c
+++ b/net/ipv4/ip_fragment.c
@@ -802,6 +802,10 @@ static int __net_init ip4_frags_ns_ctl_register(struct net *net)
 		table[0].data = &net->ipv4.frags.high_thresh;
 		table[1].data = &net->ipv4.frags.low_thresh;
 		table[2].data = &net->ipv4.frags.timeout;
+
+		/* Don't export sysctls to unprivileged users */
+		if (net->user_ns != &init_user_ns)
+			table[0].procname = NULL;
 	}
 
 	hdr = register_net_sysctl(net, "net/ipv4", table);
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index a8c651216fa62..5b58788db863c 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -2493,6 +2493,10 @@ static __net_init int sysctl_route_net_init(struct net *net)
 		tbl = kmemdup(tbl, sizeof(ipv4_route_flush_table), GFP_KERNEL);
 		if (tbl == NULL)
 			goto err_dup;
+
+		/* Don't export sysctls to unprivileged users */
+		if (net->user_ns != &init_user_ns)
+			tbl[0].procname = NULL;
 	}
 	tbl[0].extra1 = net;
 
diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
index 63d4eccc674dd..d84400b65049e 100644
--- a/net/ipv4/sysctl_net_ipv4.c
+++ b/net/ipv4/sysctl_net_ipv4.c
@@ -883,6 +883,9 @@ static __net_init int ipv4_sysctl_init_net(struct net *net)
 		table[6].data =
 			&net->ipv4.sysctl_ping_group_range;
 
+		/* Don't export sysctls to unprivileged users */
+		if (net->user_ns != &init_user_ns)
+			table[0].procname = NULL;
 	}
 
 	/*
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index cb803b7bb0d8d..b24b4de5cd263 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -4735,6 +4735,10 @@ static int __addrconf_sysctl_register(struct net *net, char *dev_name,
 		t->addrconf_vars[i].extra2 = net;
 	}
 
+	/* Don't export sysctls to unprivileged users */
+	if (net->user_ns != &init_user_ns)
+		t->addrconf_vars[0].procname = NULL;
+
 	snprintf(path, sizeof(path), "net/ipv6/conf/%s", dev_name);
 
 	t->sysctl_header = register_net_sysctl(net, path, t->addrconf_vars);
diff --git a/net/ipv6/icmp.c b/net/ipv6/icmp.c
index b4a9fd51dae74..d77dc1e2a42bc 100644
--- a/net/ipv6/icmp.c
+++ b/net/ipv6/icmp.c
@@ -967,9 +967,14 @@ struct ctl_table * __net_init ipv6_icmp_sysctl_init(struct net *net)
 			sizeof(ipv6_icmp_table_template),
 			GFP_KERNEL);
 
-	if (table)
+	if (table) {
 		table[0].data = &net->ipv6.sysctl.icmpv6_time;
 
+		/* Don't export sysctls to unprivileged users */
+		if (net->user_ns != &init_user_ns)
+			table[0].procname = NULL;
+	}
+
 	return table;
 }
 #endif
diff --git a/net/ipv6/reassembly.c b/net/ipv6/reassembly.c
index da8a4e301b1b0..e5253ec9e0fcd 100644
--- a/net/ipv6/reassembly.c
+++ b/net/ipv6/reassembly.c
@@ -616,6 +616,10 @@ static int __net_init ip6_frags_ns_sysctl_register(struct net *net)
 		table[0].data = &net->ipv6.frags.high_thresh;
 		table[1].data = &net->ipv6.frags.low_thresh;
 		table[2].data = &net->ipv6.frags.timeout;
+
+		/* Don't export sysctls to unprivileged users */
+		if (net->user_ns != &init_user_ns)
+			table[0].procname = NULL;
 	}
 
 	hdr = register_net_sysctl(net, "net/ipv6", table);
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 11249d211ea9a..021a48e8a5e2e 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -2989,6 +2989,10 @@ struct ctl_table * __net_init ipv6_route_sysctl_init(struct net *net)
 		table[7].data = &net->ipv6.sysctl.ip6_rt_mtu_expires;
 		table[8].data = &net->ipv6.sysctl.ip6_rt_min_advmss;
 		table[9].data = &net->ipv6.sysctl.ip6_rt_gc_min_interval;
+
+		/* Don't export sysctls to unprivileged users */
+		if (net->user_ns != &init_user_ns)
+			table[0].procname = NULL;
 	}
 
 	return table;
diff --git a/net/ipv6/sysctl_net_ipv6.c b/net/ipv6/sysctl_net_ipv6.c
index e85c48bd404f4..b06fd078e6c7a 100644
--- a/net/ipv6/sysctl_net_ipv6.c
+++ b/net/ipv6/sysctl_net_ipv6.c
@@ -52,6 +52,10 @@ static int __net_init ipv6_sysctl_net_init(struct net *net)
 		goto out;
 	ipv6_table[0].data = &net->ipv6.sysctl.bindv6only;
 
+	/* Don't export sysctls to unprivileged users */
+	if (net->user_ns != &init_user_ns)
+		ipv6_table[0].procname = NULL;
+
 	ipv6_route_table = ipv6_route_sysctl_init(net);
 	if (!ipv6_route_table)
 		goto out_ipv6_table;
diff --git a/net/netfilter/ipvs/ip_vs_ctl.c b/net/netfilter/ipvs/ip_vs_ctl.c
index c4ee43710aab6..c6cebd560936b 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 cbd37489ac77b..d742aa9780ec3 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 161b67972e3f6..c03b6a3ade2f9 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 d61e0782a797d..7df424e2d10cf 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 de9781b6464f0..faa978f1714b8 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 c4bc637feb76b..884f2b39319a2 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 6535326cf07c7..a8ae287bc7afe 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 9b3943252a5e9..363285d544a1c 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 dbb364f62d6f0..7ea8026f07c9c 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) {
diff --git a/net/unix/sysctl_net_unix.c b/net/unix/sysctl_net_unix.c
index b34b5b9792f0e..8800604c93f45 100644
--- a/net/unix/sysctl_net_unix.c
+++ b/net/unix/sysctl_net_unix.c
@@ -34,6 +34,10 @@ int __net_init unix_sysctl_register(struct net *net)
 	if (table == NULL)
 		goto err_alloc;
 
+	/* Don't export sysctls to unprivileged users */
+	if (net->user_ns != &init_user_ns)
+		table[0].procname = NULL;
+
 	table[0].data = &net->unx.sysctl_max_dgram_qlen;
 	net->unx.ctl = register_net_sysctl(net, "net/unix", table);
 	if (net->unx.ctl == NULL)
diff --git a/net/xfrm/xfrm_sysctl.c b/net/xfrm/xfrm_sysctl.c
index 380976f74c4c9..05a6e3d9c258c 100644
--- a/net/xfrm/xfrm_sysctl.c
+++ b/net/xfrm/xfrm_sysctl.c
@@ -54,6 +54,10 @@ int __net_init xfrm_sysctl_init(struct net *net)
 	table[2].data = &net->xfrm.sysctl_larval_drop;
 	table[3].data = &net->xfrm.sysctl_acq_expires;
 
+	/* Don't export sysctls to unprivileged users */
+	if (net->user_ns != &init_user_ns)
+		table[0].procname = NULL;
+
 	net->xfrm.sysctl_hdr = register_net_sysctl(net, "net/core", table);
 	if (!net->xfrm.sysctl_hdr)
 		goto out_register;
-- 
2.39.5