[PATCH] !!!! HERE BE DRAGONS - UNTESTED !!!!

[Christian Brauner]

---
 security/integrity/ima/ima_fs.c | 43 +++++++++++++++++++++++++++++----
 1 file changed, 38 insertions(+), 5 deletions(-)

diff --git a/security/integrity/ima/ima_fs.c b/security/integrity/ima/ima_fs.c
index 583462b29cb5..d5b302b925b8 100644
--- a/security/integrity/ima/ima_fs.c
+++ b/security/integrity/ima/ima_fs.c
@@ -317,10 +317,14 @@ static ssize_t ima_read_policy(char *path)
 static ssize_t ima_write_policy(struct file *file, const char __user *buf,
 				size_t datalen, loff_t *ppos)
 {
-	struct ima_namespace *ns = get_current_ns();
+	struct ima_namespace *ns;
+	struct user_namespace *user_ns;
 	char *data;
 	ssize_t result;
 
+	user_ns = ima_filp_private(filp);
+	ns = user_ns->ima_ns
+
 	if (datalen >= PAGE_SIZE)
 		datalen = PAGE_SIZE - 1;
 
@@ -373,26 +377,51 @@ static const struct seq_operations ima_policy_seqops = {
 };
 #endif
 
+static struct user_namespace *ima_filp_private(struct file *filp)
+{
+	if (!(filp->f_flags & O_WRONLY)) {
+#ifdef CONFIG_IMA_READ_POLICY
+		struct seq_file *seq;
+
+		seq = filp->private_data;
+		return seq->private;
+#endif
+	}
+	return filp->private_data;
+}
+
 /*
  * ima_open_policy: sequentialize access to the policy file
  */
 static int ima_open_policy(struct inode *inode, struct file *filp)
 {
-	struct ima_namespace *ns = get_current_ns();
+	struct user_namespace *user_ns = current_user_ns();
+	struct ima_namespace *ns = user_ns->ima_ns;
 
 	if (!(filp->f_flags & O_WRONLY)) {
 #ifndef	CONFIG_IMA_READ_POLICY
 		return -EACCES;
 #else
+		int err;
+		struct seq_file *seq;
+
 		if ((filp->f_flags & O_ACCMODE) != O_RDONLY)
 			return -EACCES;
-		if (!mac_admin_ns_capable(ima_user_ns(ns)))
+		if (!mac_admin_ns_capable(user_ns))
 			return -EPERM;
-		return seq_open(filp, &ima_policy_seqops);
+		err = seq_open(filp, &ima_policy_seqops);
+		if (err)
+			return err;
+
+		seq = filp->private_data;
+		seq->private = user_ns;
+		return 0;
 #endif
 	}
 	if (test_and_set_bit(IMA_FS_BUSY, &ns->ima_fs_flags))
 		return -EBUSY;
+
+	filp->private_data = user_ns;
 	return 0;
 }
 
@@ -405,9 +434,13 @@ static int ima_open_policy(struct inode *inode, struct file *filp)
  */
 static int ima_release_policy(struct inode *inode, struct file *file)
 {
-	struct ima_namespace *ns = get_current_ns();
+	struct ima_namespace *ns;
+	struct user_namespace *user_ns;
 	const char *cause = ns->valid_policy ? "completed" : "failed";
 
+	user_ns = ima_filp_private(filp);
+	ns = user_ns->ima_ns
+
 	if ((file->f_flags & O_ACCMODE) == O_RDONLY)
 		return seq_release(inode, file);
 
-- 
2.30.2