[PATCH net-next v6 2/8] net: ipv{6,4}: Remove the now superfluous sentinel elements from ctl_table array

Joel Granados via B4 Relay
2024-05-01T09:30:09Z

This commit comes at the tail end of a greater effort to remove the
empty elements at the end of the ctl_table arrays (sentinels) which
will reduce the overall build time size of the kernel and run time
memory bloat by ~64 bytes per sentinel (further information Link :
https://lore.kernel.org/all/ZO5Yx5JFogGi%2FcBo@bombadil.infradead.org/)

* Remove sentinel element from ctl_table structs.
* Remove the zeroing out of an array element (to make it look like a
sentinel) in sysctl_route_net_init And ipv6_route_sysctl_init.
This is not longer needed and is safe after commit c899710fe7f9
("networking: Update to register_net_sysctl_sz") added the array size
to the ctl_table registration.
* Remove extra sentinel element in the declaration of devinet_vars.
* Removed the "-1" in __devinet_sysctl_register, sysctl_route_net_init,
ipv6_sysctl_net_init and ipv4_sysctl_init_net that adjusted for having
an extra empty element when looping over ctl_table arrays
* Replace the for loop stop condition in __addrconf_sysctl_register that
tests for procname == NULL with one that depends on array size
* Removing the unprivileged user check in ipv6_route_sysctl_init is
safe as it is replaced by calling ipv6_route_sysctl_table_size;
introduced in commit c899710fe7f9 ("networking: Update to
register_net_sysctl_sz")
* Use a table_size variable to keep the value of ARRAY_SIZE

Signed-off-by: Joel Granados <j.granados@samsung.com>
---
net/ipv4/devinet.c | 5 ++---
net/ipv4/ip_fragment.c | 2 --
net/ipv4/route.c | 8 ++------
net/ipv4/sysctl_net_ipv4.c | 7 +++----
net/ipv4/xfrm4_policy.c | 1 -
net/ipv6/addrconf.c | 8 +++-----
net/ipv6/icmp.c | 1 -
net/ipv6/reassembly.c | 2 --
net/ipv6/route.c | 5 -----
net/ipv6/sysctl_net_ipv6.c | 8 +++-----
net/ipv6/xfrm6_policy.c | 1 -
11 files changed, 13 insertions(+), 35 deletions(-)

diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
index 364dbf0cd9bf..a612c57b61c5 100644
--- a/net/ipv4/devinet.c
+++ b/net/ipv4/devinet.c
@@ -2520,7 +2520,7 @@ static int ipv4_doint_and_flush(struct ctl_table *ctl, int write,

static struct devinet_sysctl_table {
struct ctl_table_header *sysctl_header;
- struct ctl_table devinet_vars[__IPV4_DEVCONF_MAX];
+ struct ctl_table devinet_vars[IPV4_DEVCONF_MAX];
} devinet_sysctl = {
.devinet_vars = {
DEVINET_SYSCTL_COMPLEX_ENTRY(FORWARDING, "forwarding",
@@ -2583,7 +2583,7 @@ static int __devinet_sysctl_register(struct net *net, char *dev_name,
if (!t)
goto out;

- for (i = 0; i < ARRAY_SIZE(t->devinet_vars) - 1; i++) {
+ for (i = 0; i < ARRAY_SIZE(t->devinet_vars); i++) {
t->devinet_vars[i].data += (char *)p - (char *)&ipv4_devconf;
t->devinet_vars[i].extra1 = p;
t->devinet_vars[i].extra2 = net;
@@ -2657,7 +2657,6 @@ static struct ctl_table ctl_forward_entry[] = {
.extra1 = &ipv4_devconf,
.extra2 = &init_net,
},
- { },
};
#endif

diff --git a/net/ipv4/ip_fragment.c b/net/ipv4/ip_fragment.c
index 534b98a0744a..08e2c92e25ab 100644
--- a/net/ipv4/ip_fragment.c
+++ b/net/ipv4/ip_fragment.c
@@ -580,7 +580,6 @@ static struct ctl_table ip4_frags_ns_ctl_table[] = {
.proc_handler = proc_dointvec_minmax,
.extra1 = &dist_min,
},
- { }
};

/* secret interval has been deprecated */
@@ -593,7 +592,6 @@ static struct ctl_table ip4_frags_ctl_table[] = {
.mode = 0644,
.proc_handler = proc_dointvec_jiffies,
},
- { }
};

static int __net_init ip4_frags_ns_ctl_register(struct net *net)
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 0fd9a3d7ac4a..5fd54103174f 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -3496,7 +3496,6 @@ static struct ctl_table ipv4_route_table[] = {
.mode = 0644,
.proc_handler = proc_dointvec,
},
- { }
};

static const char ipv4_route_flush_procname[] = "flush";
@@ -3530,7 +3529,6 @@ static struct ctl_table ipv4_route_netns_table[] = {
.mode = 0644,
.proc_handler = proc_dointvec,
},
- { },
};

static __net_init int sysctl_route_net_init(struct net *net)
@@ -3548,16 +3546,14 @@ 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) {
- tbl[0].procname = NULL;
+ if (tbl[0].procname != ipv4_route_flush_procname)
table_size = 0;
- }
}

/* Update the variables to point into the current struct net
* except for the first element flush
*/
- for (i = 1; i < ARRAY_SIZE(ipv4_route_netns_table) - 1; i++)
+ for (i = 1; i < table_size; i++)
tbl[i].data += (void *)net - (void *)&init_net;
}
tbl[0].extra1 = net;
diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
index ce5d19978a26..162a0a3b6ba5 100644
--- a/net/ipv4/sysctl_net_ipv4.c
+++ b/net/ipv4/sysctl_net_ipv4.c
@@ -575,7 +575,6 @@ static struct ctl_table ipv4_table[] = {
.extra1 = &sysctl_fib_sync_mem_min,
.extra2 = &sysctl_fib_sync_mem_max,
},
- { }
};

static struct ctl_table ipv4_net_table[] = {
@@ -1502,11 +1501,11 @@ static struct ctl_table ipv4_net_table[] = {
.proc_handler = proc_dou8vec_minmax,
.extra1 = SYSCTL_ONE,
},
- { }
};

static __net_init int ipv4_sysctl_init_net(struct net *net)
{
+ size_t table_size = ARRAY_SIZE(ipv4_net_table);
struct ctl_table *table;

table = ipv4_net_table;
@@ -1517,7 +1516,7 @@ static __net_init int ipv4_sysctl_init_net(struct net *net)
if (!table)
goto err_alloc;

- for (i = 0; i < ARRAY_SIZE(ipv4_net_table) - 1; i++) {
+ for (i = 0; i < table_size; i++) {
if (table[i].data) {
/* Update the variables to point into
* the current struct net
@@ -1533,7 +1532,7 @@ static __net_init int ipv4_sysctl_init_net(struct net *net)
}

net->ipv4.ipv4_hdr = register_net_sysctl_sz(net, "net/ipv4", table,
- ARRAY_SIZE(ipv4_net_table));
+ table_size);
if (!net->ipv4.ipv4_hdr)
goto err_reg;

diff --git a/net/ipv4/xfrm4_policy.c b/net/ipv4/xfrm4_policy.c
index fccbbd3e1a4b..0294fef577fa 100644
--- a/net/ipv4/xfrm4_policy.c
+++ b/net/ipv4/xfrm4_policy.c
@@ -152,7 +152,6 @@ static struct ctl_table xfrm4_policy_table[] = {
.mode = 0644,
.proc_handler = proc_dointvec,
},
- { }
};

static __net_init int xfrm4_net_sysctl_init(struct net *net)
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 9aa0900abfa1..5c424a0e7232 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -7184,14 +7184,12 @@ static const struct ctl_table addrconf_sysctl[] = {
.extra1 = SYSCTL_ZERO,
.extra2 = SYSCTL_TWO,
},
- {
- /* sentinel */
- }
};

static int __addrconf_sysctl_register(struct net *net, char *dev_name,
struct inet6_dev *idev, struct ipv6_devconf *p)
{
+ size_t table_size = ARRAY_SIZE(addrconf_sysctl);
int i, ifindex;
struct ctl_table *table;
char path[sizeof("net/ipv6/conf/") + IFNAMSIZ];
@@ -7200,7 +7198,7 @@ static int __addrconf_sysctl_register(struct net *net, char *dev_name,
if (!table)
goto out;

- for (i = 0; table[i].data; i++) {
+ for (i = 0; i < table_size; i++) {
table[i].data += (char *)p - (char *)&ipv6_devconf;
/* If one of these is already set, then it is not safe to
* overwrite either of them: this makes proc_dointvec_minmax
@@ -7215,7 +7213,7 @@ 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_sz(net, path, table,
- ARRAY_SIZE(addrconf_sysctl));
+ table_size);
if (!p->sysctl_header)
goto free;

diff --git a/net/ipv6/icmp.c b/net/ipv6/icmp.c
index d285c1f6f1a6..7b31674644ef 100644
--- a/net/ipv6/icmp.c
+++ b/net/ipv6/icmp.c
@@ -1206,7 +1206,6 @@ static struct ctl_table ipv6_icmp_table_template[] = {
.extra1 = SYSCTL_ZERO,
.extra2 = SYSCTL_ONE,
},
- { },
};

struct ctl_table * __net_init ipv6_icmp_sysctl_init(struct net *net)
diff --git a/net/ipv6/reassembly.c b/net/ipv6/reassembly.c
index ee95cdcc8747..439f93512b0a 100644
--- a/net/ipv6/reassembly.c
+++ b/net/ipv6/reassembly.c
@@ -436,7 +436,6 @@ static struct ctl_table ip6_frags_ns_ctl_table[] = {
.mode = 0644,
.proc_handler = proc_dointvec_jiffies,
},
- { }
};

/* secret interval has been deprecated */
@@ -449,7 +448,6 @@ static struct ctl_table ip6_frags_ctl_table[] = {
.mode = 0644,
.proc_handler = proc_dointvec_jiffies,
},
- { }
};

static int __net_init ip6_frags_ns_sysctl_register(struct net *net)
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 3e0b2cb20fd2..c43b0616742e 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -6428,7 +6428,6 @@ static struct ctl_table ipv6_route_table_template[] = {
.extra1 = SYSCTL_ZERO,
.extra2 = SYSCTL_ONE,
},
- { }
};

struct ctl_table * __net_init ipv6_route_sysctl_init(struct net *net)
@@ -6452,10 +6451,6 @@ 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;
diff --git a/net/ipv6/sysctl_net_ipv6.c b/net/ipv6/sysctl_net_ipv6.c
index 75de55f907b0..c060285ff47f 100644
--- a/net/ipv6/sysctl_net_ipv6.c
+++ b/net/ipv6/sysctl_net_ipv6.c
@@ -213,7 +213,6 @@ static struct ctl_table ipv6_table_template[] = {
.proc_handler = proc_doulongvec_minmax,
.extra2 = &ioam6_id_wide_max,
},
- { }
};

static struct ctl_table ipv6_rotable[] = {
@@ -248,11 +247,11 @@ static struct ctl_table ipv6_rotable[] = {
.proc_handler = proc_dointvec,
},
#endif /* CONFIG_NETLABEL */
- { }
};

static int __net_init ipv6_sysctl_net_init(struct net *net)
{
+ size_t table_size = ARRAY_SIZE(ipv6_table_template);
struct ctl_table *ipv6_table;
struct ctl_table *ipv6_route_table;
struct ctl_table *ipv6_icmp_table;
@@ -264,7 +263,7 @@ static int __net_init ipv6_sysctl_net_init(struct net *net)
if (!ipv6_table)
goto out;
/* Update the variables to point into the current struct net */
- for (i = 0; i < ARRAY_SIZE(ipv6_table_template) - 1; i++)
+ for (i = 0; i < table_size; i++)
ipv6_table[i].data += (void *)net - (void *)&init_net;

ipv6_route_table = ipv6_route_sysctl_init(net);
@@ -276,8 +275,7 @@ static int __net_init ipv6_sysctl_net_init(struct net *net)
goto out_ipv6_route_table;

net->ipv6.sysctl.hdr = register_net_sysctl_sz(net, "net/ipv6",
- ipv6_table,
- ARRAY_SIZE(ipv6_table_template));
+ ipv6_table, table_size);
if (!net->ipv6.sysctl.hdr)
goto out_ipv6_icmp_table;

diff --git a/net/ipv6/xfrm6_policy.c b/net/ipv6/xfrm6_policy.c
index 7924e08ee142..cc885d3aa9e5 100644
--- a/net/ipv6/xfrm6_policy.c
+++ b/net/ipv6/xfrm6_policy.c
@@ -184,7 +184,6 @@ static struct ctl_table xfrm6_policy_table[] = {
.mode = 0644,
.proc_handler = proc_dointvec,
},
- { }
};

static int __net_init xfrm6_net_sysctl_init(struct net *net)

--
2.43.0