Patch "vfs: open() with O_CREAT should not create inodes with unknown ids" has been added to the 4.9-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    vfs: open() with O_CREAT should not create inodes with unknown ids

to the 4.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     vfs-open-with-o_creat-should-not-create-inodes-with-unknown-ids.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From foo@baz Mon Nov  6 10:07:35 CET 2017
From: Seth Forshee <seth.forshee@canonical.com>
Date: Sat, 7 Oct 2017 22:36:55 +0000
Subject: vfs: open() with O_CREAT should not create inodes with unknown ids

From: Seth Forshee <seth.forshee@canonical.com>


[ Upstream commit 1328c727004d432bbdfba0ffa02a166df04c7305 ]

may_create() rejects creation of inodes with ids which lack a
mapping into s_user_ns. However for O_CREAT may_o_create() is
is used instead. Add a similar check there.

Fixes: 036d523641c6 ("vfs: Don't create inodes with a uid or gid unknown to the vfs")
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 fs/namei.c |    6 ++++++
 1 file changed, 6 insertions(+)

--- a/fs/namei.c
+++ b/fs/namei.c
@@ -2971,10 +2971,16 @@ static inline int open_to_namei_flags(in
 
 static int may_o_create(const struct path *dir, struct dentry *dentry, umode_t mode)
 {
+	struct user_namespace *s_user_ns;
 	int error = security_path_mknod(dir, dentry, mode, 0);
 	if (error)
 		return error;
 
+	s_user_ns = dir->dentry->d_sb->s_user_ns;
+	if (!kuid_has_mapping(s_user_ns, current_fsuid()) ||
+	    !kgid_has_mapping(s_user_ns, current_fsgid()))
+		return -EOVERFLOW;
+
 	error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC);
 	if (error)
 		return error;


Patches currently in stable-queue which might be from seth.forshee@canonical.com are

queue-4.9/vfs-open-with-o_creat-should-not-create-inodes-with-unknown-ids.patch