diff mbox series

[v6,11/17] securityfs: Only use simple_pin_fs/simple_release_fs for init_user_ns

Message ID 20211210194736.1538863-12-stefanb@linux.ibm.com (mailing list archive)
State New, archived
Headers show
Series ima: Namespace IMA with audit support in IMA-ns | expand

Commit Message

Stefan Berger Dec. 10, 2021, 7:47 p.m. UTC 
To prepare for virtualization of SecurityFS, use simple_pin_fs and
simpe_release_fs only when init_user_ns is active.

Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
---
 security/inode.c | 34 +++++++++++++++++++++++++---------
 1 file changed, 25 insertions(+), 9 deletions(-)
diff mbox series

Patch

diff --git a/security/inode.c b/security/inode.c
index 6c326939750d..fee01ff4d831 100644
--- a/security/inode.c
+++ b/security/inode.c
@@ -21,9 +21,10 @@ 
 #include <linux/security.h>
 #include <linux/lsm_hooks.h>
 #include <linux/magic.h>
+#include <linux/user_namespace.h>
 
-static struct vfsmount *mount;
-static int mount_count;
+static struct vfsmount *init_securityfs_mount;
+static int init_securityfs_mount_count;
 
 static void securityfs_free_inode(struct inode *inode)
 {
@@ -109,6 +110,7 @@  static struct dentry *securityfs_create_dentry(const char *name, umode_t mode,
 					const struct file_operations *fops,
 					const struct inode_operations *iops)
 {
+	struct user_namespace *ns = current_user_ns();
 	struct dentry *dentry;
 	struct inode *dir, *inode;
 	int error;
@@ -118,12 +120,19 @@  static struct dentry *securityfs_create_dentry(const char *name, umode_t mode,
 
 	pr_debug("securityfs: creating file '%s'\n",name);
 
-	error = simple_pin_fs(&fs_type, &mount, &mount_count);
-	if (error)
-		return ERR_PTR(error);
+	if (ns == &init_user_ns) {
+		error = simple_pin_fs(&fs_type, &init_securityfs_mount,
+				      &init_securityfs_mount_count);
+		if (error)
+			return ERR_PTR(error);
+	}
 
-	if (!parent)
-		parent = mount->mnt_root;
+	if (!parent) {
+		if (ns == &init_user_ns)
+			parent = init_securityfs_mount->mnt_root;
+		else
+			return ERR_PTR(-EINVAL);
+	}
 
 	dir = d_inode(parent);
 
@@ -168,7 +177,9 @@  static struct dentry *securityfs_create_dentry(const char *name, umode_t mode,
 	dentry = ERR_PTR(error);
 out:
 	inode_unlock(dir);
-	simple_release_fs(&mount, &mount_count);
+	if (ns == &init_user_ns)
+		simple_release_fs(&init_securityfs_mount,
+				  &init_securityfs_mount_count);
 	return dentry;
 }
 
@@ -294,11 +305,14 @@  EXPORT_SYMBOL_GPL(securityfs_create_symlink);
  */
 void securityfs_remove(struct dentry *dentry)
 {
+	struct user_namespace *ns;
 	struct inode *dir;
 
 	if (!dentry || IS_ERR(dentry))
 		return;
 
+	ns = dentry->d_sb->s_user_ns;
+
 	dir = d_inode(dentry->d_parent);
 	inode_lock(dir);
 	if (simple_positive(dentry)) {
@@ -309,7 +323,9 @@  void securityfs_remove(struct dentry *dentry)
 		dput(dentry);
 	}
 	inode_unlock(dir);
-	simple_release_fs(&mount, &mount_count);
+	if (ns == &init_user_ns)
+		simple_release_fs(&init_securityfs_mount,
+				  &init_securityfs_mount_count);
 }
 EXPORT_SYMBOL_GPL(securityfs_remove);