[RFC,26/62] keys/mktme: Move the MKTME payload into a cache aligned structure

Commit Message

[e-mail] May 8, 2019, 2:43 p.m. UTC

From: Alison Schofield <[e-mail]>

In preparation for programming the key into the hardware, move
the key payload into a cache aligned structure. This alignment
is a requirement of the MKTME hardware.

Use the slab allocator to have this structure readily available.

Signed-off-by: Alison Schofield <[e-mail]>
Signed-off-by: Kirill A. Shutemov <[e-mail]>
---
 security/keys/mktme_keys.c | 39 ++++++++++++++++++++++++++++++++++++--
 1 file changed, 37 insertions(+), 2 deletions(-)

Comments

Peter Zijlstra June 14, 2019, 11:35 a.m. UTC | #1

On Wed, May 08, 2019 at 05:43:46PM +0300, Kirill A. Shutemov wrote:

> +/* Copy the payload to the HW programming structure and program this KeyID */
> +static int mktme_program_keyid(int keyid, struct mktme_payload *payload)
> +{
> +	struct mktme_key_program *kprog = NULL;
> +	int ret;
> +
> +	kprog = kmem_cache_zalloc(mktme_prog_cache, GFP_ATOMIC);

Why GFP_ATOMIC, afaict neither of the usage is with a spinlock held.

> +	if (!kprog)
> +		return -ENOMEM;
> +
> +	/* Hardware programming requires cached aligned struct */
> +	kprog->keyid = keyid;
> +	kprog->keyid_ctrl = payload->keyid_ctrl;
> +	memcpy(kprog->key_field_1, payload->data_key, MKTME_AES_XTS_SIZE);
> +	memcpy(kprog->key_field_2, payload->tweak_key, MKTME_AES_XTS_SIZE);
> +
> +	ret = MKTME_PROG_SUCCESS;	/* Future programming call */
> +	kmem_cache_free(mktme_prog_cache, kprog);
> +	return ret;
> +}

Alison Schofield June 14, 2019, 5:10 p.m. UTC | #2

On Fri, Jun 14, 2019 at 01:35:23PM +0200, Peter Zijlstra wrote:
> On Wed, May 08, 2019 at 05:43:46PM +0300, Kirill A. Shutemov wrote:
> 
> > +/* Copy the payload to the HW programming structure and program this KeyID */
> > +static int mktme_program_keyid(int keyid, struct mktme_payload *payload)
> > +{
> > +	struct mktme_key_program *kprog = NULL;
> > +	int ret;
> > +
> > +	kprog = kmem_cache_zalloc(mktme_prog_cache, GFP_ATOMIC);
> 
> Why GFP_ATOMIC, afaict neither of the usage is with a spinlock held.

Got it. GFP_ATOMIC not needed.
That said, this is an artifact of reworking the locking, and that 
locking may need to change again. If it does, will try to pre-allocate
rather than depend on GFP_ATOMIC here.

> 
> > +	if (!kprog)
> > +		return -ENOMEM;
> > +
> > +	/* Hardware programming requires cached aligned struct */
> > +	kprog->keyid = keyid;
> > +	kprog->keyid_ctrl = payload->keyid_ctrl;
> > +	memcpy(kprog->key_field_1, payload->data_key, MKTME_AES_XTS_SIZE);
> > +	memcpy(kprog->key_field_2, payload->tweak_key, MKTME_AES_XTS_SIZE);
> > +
> > +	ret = MKTME_PROG_SUCCESS;	/* Future programming call */
> > +	kmem_cache_free(mktme_prog_cache, kprog);
> > +	return ret;
> > +}

Patch

diff --git a/security/keys/mktme_keys.c b/security/keys/mktme_keys.c
index 14bc4e600978..a7ca32865a1c 100644
--- a/security/keys/mktme_keys.c
+++ b/security/keys/mktme_keys.c
@@ -15,6 +15,7 @@ 
 #include "internal.h"
 
 static DEFINE_SPINLOCK(mktme_lock);
+struct kmem_cache *mktme_prog_cache;	/* Hardware programming cache */
 
 /* 1:1 Mapping between Userspace Keys (struct key) and Hardware KeyIDs */
 struct mktme_mapping {
@@ -97,6 +98,27 @@  struct mktme_payload {
 	u8		tweak_key[MKTME_AES_XTS_SIZE];
 };
 
+/* Copy the payload to the HW programming structure and program this KeyID */
+static int mktme_program_keyid(int keyid, struct mktme_payload *payload)
+{
+	struct mktme_key_program *kprog = NULL;
+	int ret;
+
+	kprog = kmem_cache_zalloc(mktme_prog_cache, GFP_ATOMIC);
+	if (!kprog)
+		return -ENOMEM;
+
+	/* Hardware programming requires cached aligned struct */
+	kprog->keyid = keyid;
+	kprog->keyid_ctrl = payload->keyid_ctrl;
+	memcpy(kprog->key_field_1, payload->data_key, MKTME_AES_XTS_SIZE);
+	memcpy(kprog->key_field_2, payload->tweak_key, MKTME_AES_XTS_SIZE);
+
+	ret = MKTME_PROG_SUCCESS;	/* Future programming call */
+	kmem_cache_free(mktme_prog_cache, kprog);
+	return ret;
+}
+
 /* Key Service Method called when a Userspace Key is garbage collected. */
 static void mktme_destroy_key(struct key *key)
 {
@@ -106,6 +128,7 @@  static void mktme_destroy_key(struct key *key)
 /* Key Service Method to create a new key. Payload is preparsed. */
 int mktme_instantiate_key(struct key *key, struct key_preparsed_payload *prep)
 {
+	struct mktme_payload *payload = prep->payload.data[0];
 	unsigned long flags;
 	int keyid;
 
@@ -114,7 +137,14 @@  int mktme_instantiate_key(struct key *key, struct key_preparsed_payload *prep)
 	spin_unlock_irqrestore(&mktme_lock, flags);
 	if (!keyid)
 		return -ENOKEY;
-	return 0;
+
+	if (!mktme_program_keyid(keyid, payload))
+		return MKTME_PROG_SUCCESS;
+
+	spin_lock_irqsave(&mktme_lock, flags);
+	mktme_release_keyid(keyid);
+	spin_unlock_irqrestore(&mktme_lock, flags);
+	return -ENOKEY;
 }
 
 /* Make sure arguments are correct for the TYPE of key requested */
@@ -275,10 +305,15 @@  static int __init init_mktme(void)
 	if (mktme_map_alloc())
 		return -ENOMEM;
 
+	/* Used to program the hardware key tables */
+	mktme_prog_cache = KMEM_CACHE(mktme_key_program, SLAB_PANIC);
+	if (!mktme_prog_cache)
+		goto free_map;
+
 	ret = register_key_type(&key_type_mktme);
 	if (!ret)
 		return ret;			/* SUCCESS */
-
+free_map:
 	kvfree(mktme_map);
 
 	return -ENOMEM;