Re: [PATCH v2 11/14] networking: Update to register_net_sysctl_sz

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On 7/31/23 09:17, Joel Granados wrote:

Move from register_net_sysctl to register_net_sysctl_sz for all the
networking related files. Do this while making sure to mirror the NULL
assignments with a table_size of zero for the unprivileged users.

We need to move to the new function in preparation for when we change
SIZE_MAX to ARRAY_SIZE() in the register_net_sysctl macro. Failing to do
so would erroneously allow ARRAY_SIZE() to be called on a pointer. We
hold off the SIZE_MAX to ARRAY_SIZE change until we have migrated all
the relevant net sysctl registering functions to register_net_sysctl_sz
in subsequent commits.

An additional size function was added to the following files in order to
calculate the size of an array that is defined in another file:
     include/net/ipv6.h
     net/ipv6/icmp.c
     net/ipv6/route.c
     net/ipv6/sysctl_net_ipv6.c

Signed-off-by: Joel Granados <j.granados@xxxxxxxxxxx>
---
  include/net/ipv6.h                  |  2 ++
  net/core/neighbour.c                |  8 ++++++--
  net/core/sysctl_net_core.c          |  3 ++-
  net/ieee802154/6lowpan/reassembly.c |  8 ++++++--
  net/ipv4/devinet.c                  |  3 ++-
  net/ipv4/ip_fragment.c              |  3 ++-
  net/ipv4/route.c                    |  8 ++++++--
  net/ipv4/sysctl_net_ipv4.c          |  3 ++-
  net/ipv4/xfrm4_policy.c             |  3 ++-
  net/ipv6/addrconf.c                 |  3 ++-
  net/ipv6/icmp.c                     |  5 +++++
  net/ipv6/reassembly.c               |  3 ++-
  net/ipv6/route.c                    | 13 +++++++++----
  net/ipv6/sysctl_net_ipv6.c          | 16 +++++++++++-----
  net/ipv6/xfrm6_policy.c             |  3 ++-
  net/mpls/af_mpls.c                  |  6 ++++--
  net/mptcp/ctrl.c                    |  3 ++-
  net/rds/tcp.c                       |  3 ++-
  net/sctp/sysctl.c                   |  4 +++-
  net/smc/smc_sysctl.c                |  3 ++-
  net/unix/sysctl_net_unix.c          |  3 ++-
  net/xfrm/xfrm_sysctl.c              |  8 ++++++--
  22 files changed, 82 insertions(+), 32 deletions(-)

diff --git a/include/net/ipv6.h b/include/net/ipv6.h
index 7332296eca44..63ba68536a20 100644
--- a/include/net/ipv6.h
+++ b/include/net/ipv6.h
@@ -1274,7 +1274,9 @@ static inline int snmp6_unregister_dev(struct inet6_dev *idev) { return 0; }
#ifdef CONFIG_SYSCTL 
  struct ctl_table *ipv6_icmp_sysctl_init(struct net *net);
+size_t ipv6_icmp_sysctl_table_size(void);
  struct ctl_table *ipv6_route_sysctl_init(struct net *net);
+size_t ipv6_route_sysctl_table_size(struct net *net);
  int ipv6_sysctl_register(void);
  void ipv6_sysctl_unregister(void);
  #endif
diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index ddd0f32de20e..adc7fc4ff9bf 100644
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -3779,6 +3779,7 @@ int neigh_sysctl_register(struct net_device *dev, struct neigh_parms *p,
  	const char *dev_name_source;
  	char neigh_path[ sizeof("net//neigh/") + IFNAMSIZ + IFNAMSIZ ];
  	char *p_name;
+	size_t neigh_vars_size;
t = kmemdup(&neigh_sysctl_template, sizeof(*t), GFP_KERNEL_ACCOUNT); 
  	if (!t)
@@ -3790,11 +3791,13 @@ int neigh_sysctl_register(struct net_device *dev, struct neigh_parms *p,
  		t->neigh_vars[i].extra2 = p;
  	}
+ neigh_vars_size = ARRAY_SIZE(t->neigh_vars); 
  	if (dev) {
  		dev_name_source = dev->name;
  		/* Terminate the table early */
  		memset(&t->neigh_vars[NEIGH_VAR_GC_INTERVAL], 0,
  		       sizeof(t->neigh_vars[NEIGH_VAR_GC_INTERVAL]));
+		neigh_vars_size = NEIGH_VAR_BASE_REACHABLE_TIME_MS;
%NEIGH_VAR_BASE_REACHABLE_TIME_MS is last usable index here, and since those are 0 based, size is one more, %NEIGH_VAR_GC_INTERVAL. 
(spelling it "NEIGH_VAR_BASE_REACHABLE_TIME_MS+1" would be perhaps better?)


  	} else {
  		struct neigh_table *tbl = p->tbl;
  		dev_name_source = "default";
@@ -3841,8 +3844,9 @@ int neigh_sysctl_register(struct net_device *dev, struct neigh_parms *p,
snprintf(neigh_path, sizeof(neigh_path), "net/%s/neigh/%s", 
  		p_name, dev_name_source);
-	t->sysctl_header =
-		register_net_sysctl(neigh_parms_net(p), neigh_path, t->neigh_vars);
+	t->sysctl_header = register_net_sysctl_sz(neigh_parms_net(p),
+						  neigh_path, t->neigh_vars,
+						  neigh_vars_size);
  	if (!t->sysctl_header)
  		goto free;
diff --git a/net/core/sysctl_net_core.c b/net/core/sysctl_net_core.c 
index 782273bb93c2..03f1edb948d7 100644
--- a/net/core/sysctl_net_core.c
+++ b/net/core/sysctl_net_core.c
@@ -712,7 +712,8 @@ static __net_init int sysctl_core_net_init(struct net *net)
  			tmp->data += (char *)net - (char *)&init_net;
  	}
- net->core.sysctl_hdr = register_net_sysctl(net, "net/core", tbl); 
+	net->core.sysctl_hdr = register_net_sysctl_sz(net, "net/core", tbl,
+						      ARRAY_SIZE(netns_core_table));
  	if (net->core.sysctl_hdr == NULL)
  		goto err_reg;
diff --git a/net/ieee802154/6lowpan/reassembly.c b/net/ieee802154/6lowpan/reassembly.c 
index a91283d1e5bf..6dd960ec558c 100644
--- a/net/ieee802154/6lowpan/reassembly.c
+++ b/net/ieee802154/6lowpan/reassembly.c
@@ -360,6 +360,7 @@ static int __net_init lowpan_frags_ns_sysctl_register(struct net *net)
  	struct ctl_table_header *hdr;
  	struct netns_ieee802154_lowpan *ieee802154_lowpan =
  		net_ieee802154_lowpan(net);
+	size_t table_size = ARRAY_SIZE(lowpan_frags_ns_ctl_table);
table = lowpan_frags_ns_ctl_table; 
  	if (!net_eq(net, &init_net)) {
@@ -369,8 +370,10 @@ static int __net_init lowpan_frags_ns_sysctl_register(struct net *net)
  			goto err_alloc;
/* Don't export sysctls to unprivileged users */ 
-		if (net->user_ns != &init_user_ns)
+		if (net->user_ns != &init_user_ns) {
  			table[0].procname = NULL;
+			table_size = 0;
+		}
  	}
table[0].data = &ieee802154_lowpan->fqdir->high_thresh; 
@@ -379,7 +382,8 @@ static int __net_init lowpan_frags_ns_sysctl_register(struct net *net)
  	table[1].extra2	= &ieee802154_lowpan->fqdir->high_thresh;
  	table[2].data	= &ieee802154_lowpan->fqdir->timeout;
- hdr = register_net_sysctl(net, "net/ieee802154/6lowpan", table); 
+	hdr = register_net_sysctl_sz(net, "net/ieee802154/6lowpan", table,
+				     table_size);
  	if (hdr == NULL)
  		goto err_reg;
diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c 
index 5deac0517ef7..89087844ea6e 100644
--- a/net/ipv4/devinet.c
+++ b/net/ipv4/devinet.c
@@ -2720,7 +2720,8 @@ static __net_init int devinet_init_net(struct net *net)
  		goto err_reg_dflt;
err = -ENOMEM; 
-	forw_hdr = register_net_sysctl(net, "net/ipv4", tbl);
+	forw_hdr = register_net_sysctl_sz(net, "net/ipv4", tbl,
+					  ARRAY_SIZE(ctl_forward_entry));
  	if (!forw_hdr)
  		goto err_reg_ctl;
  	net->ipv4.forw_hdr = forw_hdr;
diff --git a/net/ipv4/ip_fragment.c b/net/ipv4/ip_fragment.c
index 69c00ffdcf3e..a4941f53b523 100644
--- a/net/ipv4/ip_fragment.c
+++ b/net/ipv4/ip_fragment.c
@@ -615,7 +615,8 @@ static int __net_init ip4_frags_ns_ctl_register(struct net *net)
  	table[2].data	= &net->ipv4.fqdir->timeout;
  	table[3].data	= &net->ipv4.fqdir->max_dist;
- hdr = register_net_sysctl(net, "net/ipv4", table); 
+	hdr = register_net_sysctl_sz(net, "net/ipv4", table,
+				     ARRAY_SIZE(ip4_frags_ns_ctl_table));
  	if (!hdr)
  		goto err_reg;
diff --git a/net/ipv4/route.c b/net/ipv4/route.c 
index 98d7e6ba7493..e7e9fba0357a 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -3592,6 +3592,7 @@ static struct ctl_table ipv4_route_netns_table[] = {
  static __net_init int sysctl_route_net_init(struct net *net)
  {
  	struct ctl_table *tbl;
+	size_t table_size = ARRAY_SIZE(ipv4_route_netns_table);
tbl = ipv4_route_netns_table; 
  	if (!net_eq(net, &init_net)) {
@@ -3603,8 +3604,10 @@ static __net_init int sysctl_route_net_init(struct net *net)
/* Don't export non-whitelisted sysctls to unprivileged users */ 
  		if (net->user_ns != &init_user_ns) {
-			if (tbl[0].procname != ipv4_route_flush_procname)
+			if (tbl[0].procname != ipv4_route_flush_procname) {
  				tbl[0].procname = NULL;
+				table_size = 0;
+			}
  		}
/* Update the variables to point into the current struct net 
@@ -3615,7 +3618,8 @@ static __net_init int sysctl_route_net_init(struct net *net)
  	}
  	tbl[0].extra1 = net;
- net->ipv4.route_hdr = register_net_sysctl(net, "net/ipv4/route", tbl); 
+	net->ipv4.route_hdr = register_net_sysctl_sz(net, "net/ipv4/route",
+						     tbl, table_size);
  	if (!net->ipv4.route_hdr)
  		goto err_reg;
  	return 0;
diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
index 2afb0870648b..6ac890b4073f 100644
--- a/net/ipv4/sysctl_net_ipv4.c
+++ b/net/ipv4/sysctl_net_ipv4.c
@@ -1519,7 +1519,8 @@ static __net_init int ipv4_sysctl_init_net(struct net *net)
  		}
  	}
- net->ipv4.ipv4_hdr = register_net_sysctl(net, "net/ipv4", table); 
+	net->ipv4.ipv4_hdr = register_net_sysctl_sz(net, "net/ipv4", table,
+						    ARRAY_SIZE(ipv4_net_table));
  	if (!net->ipv4.ipv4_hdr)
  		goto err_reg;
diff --git a/net/ipv4/xfrm4_policy.c b/net/ipv4/xfrm4_policy.c 
index 9403bbaf1b61..57ea394ffa8c 100644
--- a/net/ipv4/xfrm4_policy.c
+++ b/net/ipv4/xfrm4_policy.c
@@ -178,7 +178,8 @@ static __net_init int xfrm4_net_sysctl_init(struct net *net)
  		table[0].data = &net->xfrm.xfrm4_dst_ops.gc_thresh;
  	}
- hdr = register_net_sysctl(net, "net/ipv4", table); 
+	hdr = register_net_sysctl_sz(net, "net/ipv4", table,
+				     ARRAY_SIZE(xfrm4_policy_table));
  	if (!hdr)
  		goto err_reg;
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c 
index e5213e598a04..d615a84965c2 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -7085,7 +7085,8 @@ static int __addrconf_sysctl_register(struct net *net, char *dev_name,
snprintf(path, sizeof(path), "net/ipv6/conf/%s", dev_name); - p->sysctl_header = register_net_sysctl(net, path, table); 
+	p->sysctl_header = register_net_sysctl_sz(net, path, table,
+						  ARRAY_SIZE(addrconf_sysctl));
  	if (!p->sysctl_header)
  		goto free;
diff --git a/net/ipv6/icmp.c b/net/ipv6/icmp.c 
index 65fa5014bc85..a76b01b41b57 100644
--- a/net/ipv6/icmp.c
+++ b/net/ipv6/icmp.c
@@ -1229,4 +1229,9 @@ struct ctl_table * __net_init ipv6_icmp_sysctl_init(struct net *net)
  	}
  	return table;
  }
+
+size_t ipv6_icmp_sysctl_table_size(void)
+{
+	return ARRAY_SIZE(ipv6_icmp_table_template);
+}
  #endif
diff --git a/net/ipv6/reassembly.c b/net/ipv6/reassembly.c
index 5bc8a28e67f9..5ebc47da1000 100644
--- a/net/ipv6/reassembly.c
+++ b/net/ipv6/reassembly.c
@@ -470,7 +470,8 @@ static int __net_init ip6_frags_ns_sysctl_register(struct net *net)
  	table[1].extra2	= &net->ipv6.fqdir->high_thresh;
  	table[2].data	= &net->ipv6.fqdir->timeout;
- hdr = register_net_sysctl(net, "net/ipv6", table); 
+	hdr = register_net_sysctl_sz(net, "net/ipv6", table,
+				     ARRAY_SIZE(ip6_frags_ns_ctl_table));
  	if (!hdr)
  		goto err_reg;
diff --git a/net/ipv6/route.c b/net/ipv6/route.c 
index 64e873f5895f..51c6cdae8723 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -6447,14 +6447,19 @@ struct ctl_table * __net_init ipv6_route_sysctl_init(struct net *net)
  		table[8].data = &net->ipv6.sysctl.ip6_rt_min_advmss;
  		table[9].data = &net->ipv6.sysctl.ip6_rt_gc_min_interval;
  		table[10].data = &net->ipv6.sysctl.skip_notify_on_dev_down;
-
-		/* Don't export sysctls to unprivileged users */
-		if (net->user_ns != &init_user_ns)
-			table[1].procname = NULL;
  	}
return table; 
  }
+
+size_t ipv6_route_sysctl_table_size(struct net *net)
+{
+	/* Don't export sysctls to unprivileged users */
+	if (net->user_ns != &init_user_ns)
+		return 0;
+
+	return ARRAY_SIZE(ipv6_route_table_template);
+}
  #endif
static int __net_init ip6_route_net_init(struct net *net) 
diff --git a/net/ipv6/sysctl_net_ipv6.c b/net/ipv6/sysctl_net_ipv6.c
index 94a0a294c6a1..888676163e90 100644
--- a/net/ipv6/sysctl_net_ipv6.c
+++ b/net/ipv6/sysctl_net_ipv6.c
@@ -275,17 +275,23 @@ static int __net_init ipv6_sysctl_net_init(struct net *net)
  	if (!ipv6_icmp_table)
  		goto out_ipv6_route_table;
- net->ipv6.sysctl.hdr = register_net_sysctl(net, "net/ipv6", ipv6_table); 
+	net->ipv6.sysctl.hdr = register_net_sysctl_sz(net, "net/ipv6",
+						      ipv6_table,
+						      ARRAY_SIZE(ipv6_table_template));
  	if (!net->ipv6.sysctl.hdr)
  		goto out_ipv6_icmp_table;
- net->ipv6.sysctl.route_hdr = 
-		register_net_sysctl(net, "net/ipv6/route", ipv6_route_table);
+	net->ipv6.sysctl.route_hdr = register_net_sysctl_sz(net,
+							    "net/ipv6/route",
+							    ipv6_route_table,
+							    ipv6_route_sysctl_table_size(net));
  	if (!net->ipv6.sysctl.route_hdr)
  		goto out_unregister_ipv6_table;
- net->ipv6.sysctl.icmp_hdr = 
-		register_net_sysctl(net, "net/ipv6/icmp", ipv6_icmp_table);
+	net->ipv6.sysctl.icmp_hdr = register_net_sysctl_sz(net,
+							   "net/ipv6/icmp",
+							   ipv6_icmp_table,
+							   ipv6_icmp_sysctl_table_size());
  	if (!net->ipv6.sysctl.icmp_hdr)
  		goto out_unregister_route_table;
diff --git a/net/ipv6/xfrm6_policy.c b/net/ipv6/xfrm6_policy.c 
index eecc5e59da17..8f931e46b460 100644
--- a/net/ipv6/xfrm6_policy.c
+++ b/net/ipv6/xfrm6_policy.c
@@ -205,7 +205,8 @@ static int __net_init xfrm6_net_sysctl_init(struct net *net)
  		table[0].data = &net->xfrm.xfrm6_dst_ops.gc_thresh;
  	}
- hdr = register_net_sysctl(net, "net/ipv6", table); 
+	hdr = register_net_sysctl_sz(net, "net/ipv6", table,
+				     ARRAY_SIZE(xfrm6_policy_table));
  	if (!hdr)
  		goto err_reg;
diff --git a/net/mpls/af_mpls.c b/net/mpls/af_mpls.c 
index bf6e81d56263..1af29af65388 100644
--- a/net/mpls/af_mpls.c
+++ b/net/mpls/af_mpls.c
@@ -1419,7 +1419,8 @@ static int mpls_dev_sysctl_register(struct net_device *dev,
snprintf(path, sizeof(path), "net/mpls/conf/%s", dev->name); - mdev->sysctl = register_net_sysctl(net, path, table); 
+	mdev->sysctl = register_net_sysctl_sz(net, path, table,
+					      ARRAY_SIZE(mpls_dev_table));
  	if (!mdev->sysctl)
  		goto free;
@@ -2689,7 +2690,8 @@ static int mpls_net_init(struct net *net) 
  	for (i = 0; i < ARRAY_SIZE(mpls_table) - 1; i++)
  		table[i].data = (char *)net + (uintptr_t)table[i].data;
- net->mpls.ctl = register_net_sysctl(net, "net/mpls", table); 
+	net->mpls.ctl = register_net_sysctl_sz(net, "net/mpls", table,
+					       ARRAY_SIZE(mpls_table));
  	if (net->mpls.ctl == NULL) {
  		kfree(table);
  		return -ENOMEM;
diff --git a/net/mptcp/ctrl.c b/net/mptcp/ctrl.c
index ae20b7d92e28..43e540328a52 100644
--- a/net/mptcp/ctrl.c
+++ b/net/mptcp/ctrl.c
@@ -150,7 +150,8 @@ static int mptcp_pernet_new_table(struct net *net, struct mptcp_pernet *pernet)
  	table[4].data = &pernet->stale_loss_cnt;
  	table[5].data = &pernet->pm_type;
- hdr = register_net_sysctl(net, MPTCP_SYSCTL_PATH, table); 
+	hdr = register_net_sysctl_sz(net, MPTCP_SYSCTL_PATH, table,
+				     ARRAY_SIZE(mptcp_sysctl_table));
  	if (!hdr)
  		goto err_reg;
diff --git a/net/rds/tcp.c b/net/rds/tcp.c 
index c5b86066ff66..2dba7505b414 100644
--- a/net/rds/tcp.c
+++ b/net/rds/tcp.c
@@ -565,7 +565,8 @@ static __net_init int rds_tcp_init_net(struct net *net)
  	}
  	tbl[RDS_TCP_SNDBUF].data = &rtn->sndbuf_size;
  	tbl[RDS_TCP_RCVBUF].data = &rtn->rcvbuf_size;
-	rtn->rds_tcp_sysctl = register_net_sysctl(net, "net/rds/tcp", tbl);
+	rtn->rds_tcp_sysctl = register_net_sysctl_sz(net, "net/rds/tcp", tbl,
+						     ARRAY_SIZE(rds_tcp_sysctl_table));
  	if (!rtn->rds_tcp_sysctl) {
  		pr_warn("could not register sysctl\n");
  		err = -ENOMEM;
diff --git a/net/sctp/sysctl.c b/net/sctp/sysctl.c
index a7a9136198fd..f65d6f92afcb 100644
--- a/net/sctp/sysctl.c
+++ b/net/sctp/sysctl.c
@@ -612,7 +612,9 @@ int sctp_sysctl_net_register(struct net *net)
  	table[SCTP_PF_RETRANS_IDX].extra2 = &net->sctp.ps_retrans;
  	table[SCTP_PS_RETRANS_IDX].extra1 = &net->sctp.pf_retrans;
- net->sctp.sysctl_header = register_net_sysctl(net, "net/sctp", table); 
+	net->sctp.sysctl_header = register_net_sysctl_sz(net, "net/sctp",
+							 table,
+							 ARRAY_SIZE(sctp_net_table));
  	if (net->sctp.sysctl_header == NULL) {
  		kfree(table);
  		return -ENOMEM;
diff --git a/net/smc/smc_sysctl.c b/net/smc/smc_sysctl.c
index b6f79fabb9d3..3ab2d8eefc55 100644
--- a/net/smc/smc_sysctl.c
+++ b/net/smc/smc_sysctl.c
@@ -81,7 +81,8 @@ int __net_init smc_sysctl_net_init(struct net *net)
  			table[i].data += (void *)net - (void *)&init_net;
  	}
- net->smc.smc_hdr = register_net_sysctl(net, "net/smc", table); 
+	net->smc.smc_hdr = register_net_sysctl_sz(net, "net/smc", table,
+						  ARRAY_SIZE(smc_table));
  	if (!net->smc.smc_hdr)
  		goto err_reg;
diff --git a/net/unix/sysctl_net_unix.c b/net/unix/sysctl_net_unix.c 
index 500129aa710c..3e84b31c355a 100644
--- a/net/unix/sysctl_net_unix.c
+++ b/net/unix/sysctl_net_unix.c
@@ -36,7 +36,8 @@ int __net_init unix_sysctl_register(struct net *net)
  		table[0].data = &net->unx.sysctl_max_dgram_qlen;
  	}
- net->unx.ctl = register_net_sysctl(net, "net/unix", table); 
+	net->unx.ctl = register_net_sysctl_sz(net, "net/unix", table,
+					      ARRAY_SIZE(unix_table));
  	if (net->unx.ctl == NULL)
  		goto err_reg;
diff --git a/net/xfrm/xfrm_sysctl.c b/net/xfrm/xfrm_sysctl.c 
index 0c6c5ef65f9d..7fdeafc838a7 100644
--- a/net/xfrm/xfrm_sysctl.c
+++ b/net/xfrm/xfrm_sysctl.c
@@ -44,6 +44,7 @@ static struct ctl_table xfrm_table[] = {
  int __net_init xfrm_sysctl_init(struct net *net)
  {
  	struct ctl_table *table;
+	size_t table_size = ARRAY_SIZE(xfrm_table);
__xfrm_sysctl_init(net); @@ -56,10 +57,13 @@ int __net_init xfrm_sysctl_init(struct net *net) 
  	table[3].data = &net->xfrm.sysctl_acq_expires;
/* Don't export sysctls to unprivileged users */ 
-	if (net->user_ns != &init_user_ns)
+	if (net->user_ns != &init_user_ns) {
  		table[0].procname = NULL;


do we still have to set procname to NULL, even if passed size is 0?
(same thing for all earlier occurences)


+		table_size = 0;
+	}
- net->xfrm.sysctl_hdr = register_net_sysctl(net, "net/core", table); 
+	net->xfrm.sysctl_hdr = register_net_sysctl_sz(net, "net/core", table,
+						      table_size);
  	if (!net->xfrm.sysctl_hdr)
  		goto out_register;
  	return 0;
overall this patch looks sane, and whole series looks very promissing, thanks
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