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Commit e79c6a4f authored by Dmitry Torokhov's avatar Dmitry Torokhov Committed by David S. Miller
Browse files

net: make net namespace sysctls belong to container's owner 



If net namespace is attached to a user namespace let's make container's
root owner of sysctls affecting said network namespace instead of global
root.

This also allows us to clean up net_ctl_permissions() because we do not
need to fudge permissions anymore for the container's owner since it now
owns the objects in question.

Acked-by: default avatar"Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: default avatarDmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent c110486f

fs/proc/proc_sysctl.c

+5 −0
Original line number Diff line number Diff line
@@ -430,6 +430,7 @@ static int sysctl_perm(struct ctl_table_header *head, struct ctl_table *table, i 
static struct inode *proc_sys_make_inode(struct super_block *sb,

		struct ctl_table_header *head, struct ctl_table *table)

{

	struct ctl_table_root *root = head->root;

	struct inode *inode;

	struct proc_inode *ei;
@@ -457,6 +458,10 @@ static struct inode *proc_sys_make_inode(struct super_block *sb, 
		if (is_empty_dir(head))

			make_empty_dir_inode(inode);

	}



	if (root->set_ownership)

		root->set_ownership(head, table, &inode->i_uid, &inode->i_gid);



out:

	return inode;

}

include/linux/sysctl.h

+4 −0
Original line number Diff line number Diff line
@@ -25,6 +25,7 @@ 
#include <linux/rcupdate.h>

#include <linux/wait.h>

#include <linux/rbtree.h>

#include <linux/uidgid.h>

#include <uapi/linux/sysctl.h>



/* For the /proc/sys support */
@@ -157,6 +158,9 @@ struct ctl_table_root { 
	struct ctl_table_set default_set;

	struct ctl_table_set *(*lookup)(struct ctl_table_root *root,

					   struct nsproxy *namespaces);

	void (*set_ownership)(struct ctl_table_header *head,

			      struct ctl_table *table,

			      kuid_t *uid, kgid_t *gid);

	int (*permissions)(struct ctl_table_header *head, struct ctl_table *table);

};

net/sysctl_net.c

+20 −9
Original line number Diff line number Diff line
@@ -42,26 +42,37 @@ static int net_ctl_permissions(struct ctl_table_header *head, 
			       struct ctl_table *table)

{

	struct net *net = container_of(head->set, struct net, sysctls);

	kuid_t root_uid = make_kuid(net->user_ns, 0);

	kgid_t root_gid = make_kgid(net->user_ns, 0);



	/* Allow network administrator to have same access as root. */

	if (ns_capable_noaudit(net->user_ns, CAP_NET_ADMIN) ||

	    uid_eq(root_uid, current_euid())) {

	if (ns_capable(net->user_ns, CAP_NET_ADMIN)) {

		int mode = (table->mode >> 6) & 7;

		return (mode << 6) | (mode << 3) | mode;

	}

	/* Allow netns root group to have the same access as the root group */

	if (in_egroup_p(root_gid)) {

		int mode = (table->mode >> 3) & 7;

		return (mode << 3) | mode;

	}



	return table->mode;

}



static void net_ctl_set_ownership(struct ctl_table_header *head,

				  struct ctl_table *table,

				  kuid_t *uid, kgid_t *gid)

{

	struct net *net = container_of(head->set, struct net, sysctls);

	kuid_t ns_root_uid;

	kgid_t ns_root_gid;



	ns_root_uid = make_kuid(net->user_ns, 0);

	if (uid_valid(ns_root_uid))

		*uid = ns_root_uid;



	ns_root_gid = make_kgid(net->user_ns, 0);

	if (gid_valid(ns_root_gid))

		*gid = ns_root_gid;

}



static struct ctl_table_root net_sysctl_root = {

	.lookup = net_ctl_header_lookup,

	.permissions = net_ctl_permissions,

	.set_ownership = net_ctl_set_ownership,

};



static int __net_init sysctl_net_init(struct net *net)