From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1166367AbeBOSWo (ORCPT ); Thu, 15 Feb 2018 13:22:44 -0500 Received: from mga14.intel.com ([192.55.52.115]:3049 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1166314AbeBOSWJ (ORCPT ); Thu, 15 Feb 2018 13:22:09 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.46,517,1511856000"; d="scan'208";a="35068986" From: Joe Konno To: linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org Cc: ard.biesheuvel@linaro.org, matthew.garrett@nebula.com, jk@ozlabs.org, ak@linux.intel.com, tony.luck@intel.com Subject: [PATCH 1/2] fs/efivarfs: restrict inode permissions Date: Thu, 15 Feb 2018 10:22:07 -0800 Message-Id: <20180215182208.35003-2-joe.konno@linux.intel.com> X-Mailer: git-send-email 2.14.1 In-Reply-To: <20180215182208.35003-1-joe.konno@linux.intel.com> References: <20180215182208.35003-1-joe.konno@linux.intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Joe Konno Efivarfs nodes are created with group and world readable permissions. Reading certain EFI variables trigger SMIs. So, this is a potential DoS surface. Make permissions more restrictive-- only the owner may read or write to created inodes. Suggested-by: Andi Kleen Reported-by: Tony Luck Cc: Ard Biesheuvel Cc: Matthew Garrett Cc: Jeremy Kerr Cc: linux-efi@vger.kernel.org Cc: stable@vger.kernel.org Signed-off-by: Joe Konno --- fs/efivarfs/super.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/fs/efivarfs/super.c b/fs/efivarfs/super.c index 5b68e4294faa..ca98c4e31eb7 100644 --- a/fs/efivarfs/super.c +++ b/fs/efivarfs/super.c @@ -145,7 +145,7 @@ static int efivarfs_callback(efi_char16_t *name16, efi_guid_t vendor, name[len + EFI_VARIABLE_GUID_LEN+1] = '\0'; - inode = efivarfs_get_inode(sb, d_inode(root), S_IFREG | 0644, 0, + inode = efivarfs_get_inode(sb, d_inode(root), S_IFREG | 0600, 0, is_removable); if (!inode) goto fail_name; @@ -207,7 +207,7 @@ static int efivarfs_fill_super(struct super_block *sb, void *data, int silent) sb->s_d_op = &efivarfs_d_ops; sb->s_time_gran = 1; - inode = efivarfs_get_inode(sb, NULL, S_IFDIR | 0755, 0, true); + inode = efivarfs_get_inode(sb, NULL, S_IFDIR | 0700, 0, true); if (!inode) return -ENOMEM; inode->i_op = &efivarfs_dir_inode_operations; -- 2.14.1