linux-kernel - [PATCH 08/14] sysctl: Add size to register_net

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Message-Id: <20230726140635.2059334-9-j.granados@samsung.com>
Date:   Wed, 26 Jul 2023 16:06:28 +0200
From:   Joel Granados <j.granados@...sung.com>
To:     mcgrof@...nel.org, "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>
Cc:     willy@...radead.org, keescook@...omium.org, josh@...htriplett.org,
        Joel Granados <j.granados@...sung.com>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 08/14] sysctl: Add size to register_net_sysctl function

This is part of the effort to remove the sentinel (last empty) element
from the ctl_table arrays.

We create a new function register_net_sysctl_sz with an extra size
argument. A macro replaces the existing register_net_sysctl. For now,
the size passed by the macro is SIZE_MAX (will eventually be ARRAY_SIZE)
to avoid compilation warnings from pointers to ctl_table arrays instead
of the arrays themselves.

Care is also taken to add table_size to the stopping criteria in such a
way that when we remove the empty sentinel element, it will continue
stopping in the last element of the ctl_table array

Signed-off-by: Joel Granados <j.granados@...sung.com>
---
 include/net/net_namespace.h | 10 ++++++----
 net/sysctl_net.c            | 22 +++++++++++++---------
 2 files changed, 19 insertions(+), 13 deletions(-)

diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h
index 78beaa765c73..e4e5fe75a281 100644
--- a/include/net/net_namespace.h
+++ b/include/net/net_namespace.h
@@ -469,15 +469,17 @@ void unregister_pernet_device(struct pernet_operations *);
 
 struct ctl_table;
 
+#define register_net_sysctl(net, path, table)	\
+	register_net_sysctl_sz(net, path, table, SIZE_MAX)
 #ifdef CONFIG_SYSCTL
 int net_sysctl_init(void);
-struct ctl_table_header *register_net_sysctl(struct net *net, const char *path,
-					     struct ctl_table *table);
+struct ctl_table_header *register_net_sysctl_sz(struct net *net, const char *path,
+					     struct ctl_table *table, size_t table_size);
 void unregister_net_sysctl_table(struct ctl_table_header *header);
 #else
 static inline int net_sysctl_init(void) { return 0; }
-static inline struct ctl_table_header *register_net_sysctl(struct net *net,
-	const char *path, struct ctl_table *table)
+static inline struct ctl_table_header *register_net_sysctl_sz(struct net *net,
+	const char *path, struct ctl_table *table, size_t table_size)
 {
 	return NULL;
 }
diff --git a/net/sysctl_net.c b/net/sysctl_net.c
index d9cbbb51b143..051ed5f6fc93 100644
--- a/net/sysctl_net.c
+++ b/net/sysctl_net.c
@@ -122,12 +122,13 @@ __init int net_sysctl_init(void)
  *    allocated.
  */
 static void ensure_safe_net_sysctl(struct net *net, const char *path,
-				   struct ctl_table *table)
+				   struct ctl_table *table, size_t table_size)
 {
 	struct ctl_table *ent;
 
 	pr_debug("Registering net sysctl (net %p): %s\n", net, path);
-	for (ent = table; ent->procname; ent++) {
+	ent = table;
+	for (size_t i = 0; i < table_size && ent->procname; ent++, i++) {
 		unsigned long addr;
 		const char *where;
 
@@ -160,21 +161,24 @@ static void ensure_safe_net_sysctl(struct net *net, const char *path,
 	}
 }
 
-struct ctl_table_header *register_net_sysctl(struct net *net,
-	const char *path, struct ctl_table *table)
+struct ctl_table_header *register_net_sysctl_sz(struct net *net,
+						const char *path,
+						struct ctl_table *table,
+						size_t table_size)
 {
-	int count = 0;
+	int count;
 	struct ctl_table *entry;
 
 	if (!net_eq(net, &init_net))
-		ensure_safe_net_sysctl(net, path, table);
+		ensure_safe_net_sysctl(net, path, table, table_size);
 
-	for (entry = table; entry->procname; entry++)
-		count++;
+	entry = table;
+	for (count = 0 ; count < table_size && entry->procname; entry++, count++)
+		;
 
 	return __register_sysctl_table(&net->sysctls, path, table, count);
 }
-EXPORT_SYMBOL_GPL(register_net_sysctl);
+EXPORT_SYMBOL_GPL(register_net_sysctl_sz);
 
 void unregister_net_sysctl_table(struct ctl_table_header *header)
 {
-- 
2.30.2