linux-kernel - [PATCH 15/29] sysctl: Initial support for auto-unregistering sysctl tables.

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <1327639925-12920-15-git-send-email-ebiederm@xmission.com>
Date:	Thu, 26 Jan 2012 20:51:51 -0800
From:	"Eric W. Biederman" <ebiederm@...ssion.com>
To:	<linux-kernel@...r.kernel.org>
Cc:	<linux-fsdevel@...r.kernel.org>, <netdev@...r.kernel.org>,
	Lucian Adrian Grijincu <lucian.grijincu@...il.com>,
	Damien Millescamps <damien.millescamps@...nd.com>,
	"Eric W. Biederman" <ebiederm@...ssion.com>
Subject: [PATCH 15/29] sysctl: Initial support for auto-unregistering sysctl tables.

Add nreg to ctl_table_header.  When nreg drops to 0 the ctl_table_header
will be unregistered.

Factor out drop_sysctl_table from unregister_sysctl_table, and add
the logic for decrementing nreg.

Signed-off-by: Eric W. Biederman <ebiederm@...ssion.com>
---
 fs/proc/proc_sysctl.c  |   28 +++++++++++++++++++---------
 include/linux/sysctl.h |    1 +
 2 files changed, 20 insertions(+), 9 deletions(-)

diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c
index 1544485..13faa48 100644
--- a/fs/proc/proc_sysctl.c
+++ b/fs/proc/proc_sysctl.c
@@ -29,8 +29,9 @@ static struct ctl_table root_table[1];
 static struct ctl_table_root sysctl_table_root;
 static struct ctl_table_header root_table_header = {
 	{{.count = 1,
-	.ctl_table = root_table,
-	.ctl_entry = LIST_HEAD_INIT(sysctl_table_root.default_set.list),}},
+	  .nreg = 1,
+	  .ctl_table = root_table,
+	  .ctl_entry = LIST_HEAD_INIT(sysctl_table_root.default_set.list),}},
 	.root = &sysctl_table_root,
 	.set = &sysctl_table_root.default_set,
 };
@@ -938,6 +939,7 @@ struct ctl_table_header *__register_sysctl_table(
 	header->unregistering = NULL;
 	header->root = root;
 	header->count = 1;
+	header->nreg = 1;
 	if (sysctl_check_table(path, table))
 		goto fail;
 
@@ -1192,6 +1194,20 @@ struct ctl_table_header *register_sysctl_table(struct ctl_table *table)
 }
 EXPORT_SYMBOL(register_sysctl_table);
 
+static void drop_sysctl_table(struct ctl_table_header *header)
+{
+	if (--header->nreg)
+		return;
+
+	start_unregistering(header);
+	if (!--header->parent->count) {
+		WARN_ON(1);
+		kfree_rcu(header->parent, rcu);
+	}
+	if (!--header->count)
+		kfree_rcu(header, rcu);
+}
+
 /**
  * unregister_sysctl_table - unregister a sysctl table hierarchy
  * @header: the header returned from register_sysctl_table
@@ -1224,13 +1240,7 @@ void unregister_sysctl_table(struct ctl_table_header * header)
 	}
 
 	spin_lock(&sysctl_lock);
-	start_unregistering(header);
-	if (!--header->parent->count) {
-		WARN_ON(1);
-		kfree_rcu(header->parent, rcu);
-	}
-	if (!--header->count)
-		kfree_rcu(header, rcu);
+	drop_sysctl_table(header);
 	spin_unlock(&sysctl_lock);
 }
 EXPORT_SYMBOL(unregister_sysctl_table);
diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
index 094bc5c..e40b8f6 100644
--- a/include/linux/sysctl.h
+++ b/include/linux/sysctl.h
@@ -1032,6 +1032,7 @@ struct ctl_table_header
 			struct list_head ctl_entry;
 			int used;
 			int count;
+			int nreg;
 		};
 		struct rcu_head rcu;
 	};
-- 
1.7.2.5

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/