From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Borislav Petkov <bp@suse.de>
Date: Mon, 4 Dec 2017 15:08:04 +0100
Subject: [PATCH] x86/mm/dump_pagetables: Add page table directory to the
 debugfs VFS hierarchy
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

CVE-2017-5754

The upcoming support for dumping the kernel and the user space page tables
of the current process would create more random files in the top level
debugfs directory.

Add a page table directory and move the existing file to it.

Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Laight <David.Laight@aculab.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Eduardo Valentin <eduval@amazon.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: aliguori@amazon.com
Cc: daniel.gruss@iaik.tugraz.at
Cc: hughd@google.com
Cc: keescook@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
(cherry picked from commit 75298aa179d56cd64f54e58a19fffc8ab922b4c0)
Signed-off-by: Andy Whitcroft <apw@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
(cherry picked from commit ae5c4af9bbefed4adc12075c28fb5889547c99cc)
Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
---
 arch/x86/mm/debug_pagetables.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/arch/x86/mm/debug_pagetables.c b/arch/x86/mm/debug_pagetables.c
index bfcffdf6c577..d1449fb6dc7a 100644
--- a/arch/x86/mm/debug_pagetables.c
+++ b/arch/x86/mm/debug_pagetables.c
@@ -22,21 +22,26 @@ static const struct file_operations ptdump_fops = {
 	.release	= single_release,
 };
 
-static struct dentry *pe;
+static struct dentry *dir, *pe;
 
 static int __init pt_dump_debug_init(void)
 {
-	pe = debugfs_create_file("kernel_page_tables", S_IRUSR, NULL, NULL,
-				 &ptdump_fops);
-	if (!pe)
+	dir = debugfs_create_dir("page_tables", NULL);
+	if (!dir)
 		return -ENOMEM;
 
+	pe = debugfs_create_file("kernel", 0400, dir, NULL, &ptdump_fops);
+	if (!pe)
+		goto err;
 	return 0;
+err:
+	debugfs_remove_recursive(dir);
+	return -ENOMEM;
 }
 
 static void __exit pt_dump_debug_exit(void)
 {
-	debugfs_remove_recursive(pe);
+	debugfs_remove_recursive(dir);
 }
 
 module_init(pt_dump_debug_init);
-- 
2.14.2

