From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf1-f197.google.com (mail-pf1-f197.google.com [209.85.210.197]) by kanga.kvack.org (Postfix) with ESMTP id D6B2D6B6D90 for ; Tue, 4 Dec 2018 02:37:26 -0500 (EST) Received: by mail-pf1-f197.google.com with SMTP id i3so13366870pfj.4 for ; Mon, 03 Dec 2018 23:37:26 -0800 (PST) Received: from mga01.intel.com (mga01.intel.com. [192.55.52.88]) by mx.google.com with ESMTPS id 28si21308808pfm.50.2018.12.03.23.37.25 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 03 Dec 2018 23:37:25 -0800 (PST) From: Alison Schofield Subject: [RFC v2 08/13] mm: Use reference counting for encrypted VMAs Date: Mon, 3 Dec 2018 23:39:55 -0800 Message-Id: <985ba614d49986fdfc0397434fd1dd9eb5646c6f.1543903910.git.alison.schofield@intel.com> In-Reply-To: References: In-Reply-To: References: Sender: owner-linux-mm@kvack.org List-ID: To: dhowells@redhat.com, tglx@linutronix.de Cc: jmorris@namei.org, mingo@redhat.com, hpa@zytor.com, bp@alien8.de, luto@kernel.org, peterz@infradead.org, kirill.shutemov@linux.intel.com, dave.hansen@intel.com, kai.huang@intel.com, jun.nakajima@intel.com, dan.j.williams@intel.com, jarkko.sakkinen@intel.com, keyrings@vger.kernel.org, linux-security-module@vger.kernel.org, linux-mm@kvack.org, x86@kernel.org The MKTME (Multi-Key Total Memory Encryption) Key Service needs a reference count on encrypted VMAs. This reference count is used to determine when a hardware encryption keyid is in use, which in turn, tells the key service what operations can be safely performed with this keyid. The approach is: 1) Increment/decrement the reference count during encrypt_mprotect() system call for initial or updated encryption on a VMA. 2) Piggy back on the new vm_area_dup/free() helpers. If the VMAs being duplicated, or freed are encrypted, adjust the reference count. Signed-off-by: Alison Schofield Signed-off-by: Kirill A. Shutemov --- arch/x86/mm/mktme.c | 2 ++ kernel/fork.c | 2 ++ 2 files changed, 4 insertions(+) diff --git a/arch/x86/mm/mktme.c b/arch/x86/mm/mktme.c index facf08f9cb74..55d34beb9b81 100644 --- a/arch/x86/mm/mktme.c +++ b/arch/x86/mm/mktme.c @@ -145,10 +145,12 @@ void mprotect_set_encrypt(struct vm_area_struct *vma, int newkeyid, if (oldkeyid == newkeyid) return; + vma_put_encrypt_ref(vma); newprot = pgprot_val(vma->vm_page_prot); newprot &= ~mktme_keyid_mask; newprot |= (unsigned long)newkeyid << mktme_keyid_shift; vma->vm_page_prot = __pgprot(newprot); + vma_get_encrypt_ref(vma); /* * The VMA doesn't have any inherited pages. diff --git a/kernel/fork.c b/kernel/fork.c index 07cddff89c7b..d12d27b50966 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -341,12 +341,14 @@ struct vm_area_struct *vm_area_dup(struct vm_area_struct *orig) if (new) { *new = *orig; INIT_LIST_HEAD(&new->anon_vma_chain); + vma_get_encrypt_ref(new); } return new; } void vm_area_free(struct vm_area_struct *vma) { + vma_put_encrypt_ref(vma); kmem_cache_free(vm_area_cachep, vma); } -- 2.14.1