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From: Alison Schofield <alison.schofield@intel.com>
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
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> (raw)
In-Reply-To: <cover.1543903910.git.alison.schofield@intel.com>

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 <alison.schofield@intel.com>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
 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


  parent reply index

Thread overview: 91+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-12-04  7:39 [RFC v2 00/13] Multi-Key Total Memory Encryption API (MKTME) Alison Schofield
2018-12-04  7:39 ` [RFC v2 01/13] x86/mktme: Document the MKTME APIs Alison Schofield
2018-12-05 18:11   ` Andy Lutomirski
2018-12-05 19:22     ` Alison Schofield
2018-12-05 23:35       ` Andy Lutomirski
2018-12-06  8:04   ` Sakkinen, Jarkko
2018-12-04  7:39 ` [RFC v2 02/13] mm: Generalize the mprotect implementation to support extensions Alison Schofield
2018-12-06  8:08   ` Sakkinen, Jarkko
2018-12-04  7:39 ` [RFC v2 03/13] syscall/x86: Wire up a new system call for memory encryption keys Alison Schofield
2018-12-04  7:39 ` [RFC v2 04/13] x86/mm: Add helper functions for MKTME " Alison Schofield
2018-12-04  9:14   ` Peter Zijlstra
2018-12-05  5:49     ` Alison Schofield
2018-12-04 15:35   ` Andy Lutomirski
2018-12-05  5:52     ` Alison Schofield
2018-12-06  8:31   ` Sakkinen, Jarkko
2018-12-04  7:39 ` [RFC v2 05/13] x86/mm: Set KeyIDs in encrypted VMAs Alison Schofield
2018-12-06  8:37   ` Sakkinen, Jarkko
2018-12-04  7:39 ` [RFC v2 06/13] mm: Add the encrypt_mprotect() system call Alison Schofield
2018-12-06  8:38   ` Sakkinen, Jarkko
2018-12-04  7:39 ` [RFC v2 07/13] x86/mm: Add helpers for reference counting encrypted VMAs Alison Schofield
2018-12-04  8:58   ` Peter Zijlstra
2018-12-05  5:28     ` Alison Schofield
2018-12-04  7:39 ` Alison Schofield [this message]
2018-12-04  7:39 ` [RFC v2 09/13] mm: Restrict memory encryption to anonymous VMA's Alison Schofield
2018-12-04  9:10   ` Peter Zijlstra
2018-12-05  5:30     ` Alison Schofield
2018-12-05  9:07       ` Peter Zijlstra
2018-12-04  7:39 ` [RFC v2 10/13] keys/mktme: Add the MKTME Key Service type for memory encryption Alison Schofield
2018-12-06  8:51   ` Sakkinen, Jarkko
2018-12-06  8:54     ` Sakkinen, Jarkko
2018-12-06 15:11     ` Dave Hansen
2018-12-06 22:56       ` Sakkinen, Jarkko
2018-12-04  7:39 ` [RFC v2 11/13] keys/mktme: Program memory encryption keys on a system wide basis Alison Schofield
2018-12-04  9:21   ` Peter Zijlstra
2018-12-04  9:50     ` Kirill A. Shutemov
2018-12-05  5:44       ` Alison Schofield
2018-12-05  5:43     ` Alison Schofield
2018-12-05  9:10       ` Peter Zijlstra
2018-12-05 17:26         ` Alison Schofield
2018-12-04  7:39 ` [RFC v2 12/13] keys/mktme: Save MKTME data if kernel cmdline parameter allows Alison Schofield
2018-12-04  9:22   ` Peter Zijlstra
2018-12-07  2:14   ` Huang, Kai
2018-12-07  3:42     ` Alison Schofield
2018-12-07  6:39     ` Jarkko Sakkinen
2018-12-07  6:45       ` Jarkko Sakkinen
2018-12-07 11:47     ` Kirill A. Shutemov
2018-12-04  7:40 ` [RFC v2 13/13] keys/mktme: Support CPU Hotplug for MKTME keys Alison Schofield
2018-12-04  9:28   ` Peter Zijlstra
2018-12-05  5:32     ` Alison Schofield
2018-12-04  9:31   ` Peter Zijlstra
2018-12-05  5:36     ` Alison Schofield
2018-12-04  9:25 ` [RFC v2 00/13] Multi-Key Total Memory Encryption API (MKTME) Peter Zijlstra
2018-12-04  9:46   ` Kirill A. Shutemov
2018-12-05 20:32     ` Sakkinen, Jarkko
2018-12-06 11:22       ` Kirill A. Shutemov
2018-12-06 14:59         ` Dave Hansen
2018-12-07 10:12           ` Huang, Kai
2018-12-06 21:23         ` Sakkinen, Jarkko
2018-12-07 11:54           ` Kirill A. Shutemov
2018-12-04 19:19 ` Andy Lutomirski
2018-12-04 20:00   ` Andy Lutomirski
2018-12-04 20:32     ` Dave Hansen
2018-12-05 22:19   ` Sakkinen, Jarkko
2018-12-07  2:05     ` Huang, Kai
2018-12-07  6:48       ` Jarkko Sakkinen
2018-12-07 11:57     ` Kirill A. Shutemov
2018-12-07 21:59       ` Sakkinen, Jarkko
2018-12-07 23:45         ` Sakkinen, Jarkko
2018-12-07 23:48           ` Andy Lutomirski
2018-12-08  1:33           ` Huang, Kai
2018-12-08  3:53             ` Sakkinen, Jarkko
2018-12-12 15:31           ` Sakkinen, Jarkko
2018-12-12 16:29             ` Andy Lutomirski
2018-12-12 16:43               ` Sakkinen, Jarkko
2018-12-12 23:27                 ` Huang, Kai
2018-12-13  5:49                   ` Sakkinen, Jarkko
2018-12-13  5:52                     ` Sakkinen, Jarkko
2018-12-12 23:24               ` Huang, Kai
2018-12-07 23:35       ` Eric Rannaud
2018-12-05 23:49   ` Dave Hansen
2018-12-06  1:09     ` Andy Lutomirski
2018-12-06  1:25       ` Dan Williams
2018-12-06 15:39       ` Dave Hansen
2018-12-06 19:10         ` Andy Lutomirski
2018-12-06 19:31           ` Dave Hansen
2018-12-07  1:55       ` Huang, Kai
2018-12-07  4:23         ` Dave Hansen
2018-12-07 23:53         ` Andy Lutomirski
2018-12-08  1:11           ` Dave Hansen
2018-12-08  2:07           ` Huang, Kai
2018-12-05 20:30 ` Sakkinen, Jarkko

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