[RFC 04/12] x86/mm: Add helper functions to manage memory encryption keys

On Mon, Sep 10, 2018 at 04:37:01PM -0700, Huang, Kai wrote:

quoted

-----Original Message-----
From: owner-linux-security-module at vger.kernel.org [mailto:owner-linux-
security-module at vger.kernel.org] On Behalf Of Huang, Kai
Sent: Monday, September 10, 2018 2:57 PM
To: Schofield, Alison <alison.schofield@intel.com>; dhowells at redhat.com;
tglx at linutronix.de
Cc: Nakajima, Jun <redacted>; Shutemov, Kirill
[off-list ref]; Hansen, Dave [off-list ref];
Sakkinen, Jarkko [off-list ref]; jmorris at namei.org;
keyrings at vger.kernel.org; linux-security-module at vger.kernel.org;
mingo at redhat.com; hpa at zytor.com; x86 at kernel.org; linux-mm at kvack.org
Subject: RE: [RFC 04/12] x86/mm: Add helper functions to manage memory
encryption keys

quoted

-----Original Message-----
From: owner-linux-security-module at vger.kernel.org [mailto:owner-linux-
security-module at vger.kernel.org] On Behalf Of Alison Schofield
Sent: Saturday, September 8, 2018 10:36 AM
To: dhowells at redhat.com; tglx at linutronix.de
Cc: Huang, Kai <redacted>; Nakajima, Jun
[off-list ref]; Shutemov, Kirill
[off-list ref]; Hansen, Dave [off-list ref];
Sakkinen, Jarkko [off-list ref]; jmorris at namei.org;
keyrings at vger.kernel.org; linux-security-module at vger.kernel.org;
mingo at redhat.com; hpa at zytor.com; x86 at kernel.org; linux-mm at kvack.org
Subject: [RFC 04/12] x86/mm: Add helper functions to manage memory
encryption keys

Define a global mapping structure to track the mapping of userspace
keys to hardware keyids in MKTME (Multi-Key Total Memory Encryption).
This data will be used for the memory encryption system call and the
kernel key service API.

Implement helper functions to access this mapping structure and make
them visible to the MKTME Kernel Key Service: security/keys/mktme_keys

Signed-off-by: Alison Schofield <alison.schofield@intel.com>
---
 arch/x86/include/asm/mktme.h | 11 ++++++
 arch/x86/mm/mktme.c          | 85
++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 96 insertions(+)

Maybe it's better to put those changes to include/keys/mktme-type.h, and
security/keys/mktme_key.c? It seems you don't have to involve linux-mm and
x86 guys by doing so?

Thanks,
-Kai

quoted

diff --git a/arch/x86/include/asm/mktme.h

b/arch/x86/include/asm/mktme.h index dbfbd955da98..f6acd551457f 100644

--- a/arch/x86/include/asm/mktme.h
+++ b/arch/x86/include/asm/mktme.h

@@ -13,6 +13,17 @@ extern phys_addr_t mktme_keyid_mask;  extern int

mktme_nr_keyids;  extern int mktme_keyid_shift;

+/* Manage mappings between hardware keyids and userspace keys */
+extern int mktme_map_alloc(void); extern void mktme_map_free(void);
+extern void mktme_map_lock(void); extern void mktme_map_unlock(void);
+extern int mktme_map_get_free_keyid(void); extern void
+mktme_map_clear_keyid(int keyid); extern void mktme_map_set_keyid(int
+keyid, unsigned int serial); extern int
+mktme_map_keyid_from_serial(unsigned int serial); extern unsigned int
+mktme_map_serial_from_keyid(int keyid);
+
 extern struct page_ext_operations page_mktme_ops;

 #define page_keyid page_keyid

diff --git a/arch/x86/mm/mktme.c b/arch/x86/mm/mktme.c index

660caf6a5ce1..5246d8323359 100644

--- a/arch/x86/mm/mktme.c
+++ b/arch/x86/mm/mktme.c

@@ -63,6 +63,91 @@ int vma_keyid(struct vm_area_struct *vma)
 	return (prot & mktme_keyid_mask) >> mktme_keyid_shift;  }

+/*
+ * struct mktme_mapping and the mktme_map_* functions manage the
+mapping
+ * of userspace keys to hardware keyids in MKTME. They are used by
+the
+ * the encrypt_mprotect system call and the MKTME Key Service API.
+ */
+struct mktme_mapping {
+	struct mutex	lock;		/* protect this map & HW state */
+	unsigned int	mapped_keyids;
+	unsigned int	serial[];
+};

Sorry one more comment that I missed yesterday:

I think 'key_serial_t' should be used  as type of serial throughout this patch, but not 'unsigned int'. 

Thanks,
-Kai

I agree! It's not an oversight, but rather a header file include nightmare.
I can look at it again.