commit 13bcc6a2853435bb5dad368bcbaa9d2a5b9c0ac4
author Eric W. Biederman <ebiederm@xmission.com> Sat Jul 16 15:22:55 2016 -0500
committer Eric W. Biederman <ebiederm@xmission.com> Mon Aug 08 09:17:16 2016 -0500
tree 3c852b1ed6545b504ea23f5353d3570f46316d16
parent 29b4817d4018df78086157ea3a55c1d9424a7cfc

sysctl: Stop implicitly passing current into sysctl_table_root.lookup

Passing nsproxy into sysctl_table_root.lookup was a premature
optimization in attempt to avoid depending on current.  The
directory /proc/self/sys has not appeared and if and when
it does this code will need to be reviewed closely and reworked
anyway.  So remove the premature optimization.

Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Serge Hallyn <serge@hallyn.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

fs/proc/proc_sysctl.c

diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c
index 1b93650..a80acdf 100644
--- a/fs/proc/proc_sysctl.c
+++ b/fs/proc/proc_sysctl.c
@@ -72,7 +72,7 @@
 
 static void drop_sysctl_table(struct ctl_table_header *header);
 static int sysctl_follow_link(struct ctl_table_header **phead,
-	struct ctl_table **pentry, struct nsproxy *namespaces);
+	struct ctl_table **pentry);
 static int insert_links(struct ctl_table_header *head);
 static void put_links(struct ctl_table_header *header);
 
@@ -319,11 +319,11 @@
 }
 
 static struct ctl_table_set *
-lookup_header_set(struct ctl_table_root *root, struct nsproxy *namespaces)
+lookup_header_set(struct ctl_table_root *root)
 {
 	struct ctl_table_set *set = &root->default_set;
 	if (root->lookup)
-		set = root->lookup(root, namespaces);
+		set = root->lookup(root);
 	return set;
 }
 
@@ -491,7 +491,7 @@
 		goto out;
 
 	if (S_ISLNK(p->mode)) {
-		ret = sysctl_follow_link(&h, &p, current->nsproxy);
+		ret = sysctl_follow_link(&h, &p);
 		err = ERR_PTR(ret);
 		if (ret)
 			goto out;
@@ -659,7 +659,7 @@
 
 	if (S_ISLNK(table->mode)) {
 		/* It is not an error if we can not follow the link ignore it */
-		int err = sysctl_follow_link(&head, &table, current->nsproxy);
+		int err = sysctl_follow_link(&head, &table);
 		if (err)
 			goto out;
 	}
@@ -976,7 +976,7 @@
 }
 
 static int sysctl_follow_link(struct ctl_table_header **phead,
-	struct ctl_table **pentry, struct nsproxy *namespaces)
+	struct ctl_table **pentry)
 {
 	struct ctl_table_header *head;
 	struct ctl_table_root *root;
@@ -988,7 +988,7 @@
 	ret = 0;
 	spin_lock(&sysctl_lock);
 	root = (*pentry)->data;
-	set = lookup_header_set(root, namespaces);
+	set = lookup_header_set(root);
 	dir = xlate_dir(set, (*phead)->parent);
 	if (IS_ERR(dir))
 		ret = PTR_ERR(dir);

include/linux/sysctl.h

diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
index 697e160..f166ca0 100644
--- a/include/linux/sysctl.h
+++ b/include/linux/sysctl.h
@@ -155,8 +155,7 @@
 
 struct ctl_table_root {
 	struct ctl_table_set default_set;
-	struct ctl_table_set *(*lookup)(struct ctl_table_root *root,
-					   struct nsproxy *namespaces);
+	struct ctl_table_set *(*lookup)(struct ctl_table_root *root);
 	int (*permissions)(struct ctl_table_header *head, struct ctl_table *table);
 };
 

net/sysctl_net.c

diff --git a/net/sysctl_net.c b/net/sysctl_net.c
index 46a71c7..ba9b5d1 100644
--- a/net/sysctl_net.c
+++ b/net/sysctl_net.c
@@ -27,9 +27,9 @@
 #endif
 
 static struct ctl_table_set *
-net_ctl_header_lookup(struct ctl_table_root *root, struct nsproxy *namespaces)
+net_ctl_header_lookup(struct ctl_table_root *root)
 {
-	return &namespaces->net_ns->sysctls;
+	return &current->nsproxy->net_ns->sysctls;
 }
 
 static int is_seen(struct ctl_table_set *set)