linux-kernel - [PATCHv2 26/59] keys/mktme: Instantiate MKTME keys

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Date:   Wed, 31 Jul 2019 18:07:40 +0300
From:   "Kirill A. Shutemov" <kirill@...temov.name>
To:     Andrew Morton <akpm@...ux-foundation.org>, x86@...nel.org,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>, Borislav Petkov <bp@...en8.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Andy Lutomirski <luto@...capital.net>,
        David Howells <dhowells@...hat.com>
Cc:     Kees Cook <keescook@...omium.org>,
        Dave Hansen <dave.hansen@...el.com>,
        Kai Huang <kai.huang@...ux.intel.com>,
        Jacob Pan <jacob.jun.pan@...ux.intel.com>,
        Alison Schofield <alison.schofield@...el.com>,
        linux-mm@...ck.org, kvm@...r.kernel.org, keyrings@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        "Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>
Subject: [PATCHv2 26/59] keys/mktme: Instantiate MKTME keys

From: Alison Schofield <alison.schofield@...el.com>

Instantiate is a Kernel Key Service method invoked when a key is
added (add_key, request_key) by the user.

During instantiation, MKTME allocates an available hardware KeyID
and maps it to the Userspace Key.

Signed-off-by: Alison Schofield <alison.schofield@...el.com>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
---
 security/keys/mktme_keys.c | 34 ++++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)

diff --git a/security/keys/mktme_keys.c b/security/keys/mktme_keys.c
index fe119a155235..beca852db01a 100644
--- a/security/keys/mktme_keys.c
+++ b/security/keys/mktme_keys.c
@@ -14,6 +14,7 @@
 
 #include "internal.h"
 
+static DEFINE_SPINLOCK(mktme_lock);
 static unsigned int mktme_available_keyids;  /* Free Hardware KeyIDs */
 
 enum mktme_keyid_state {
@@ -31,6 +32,24 @@ struct mktme_mapping {
 
 static struct mktme_mapping *mktme_map;
 
+int mktme_reserve_keyid(struct key *key)
+{
+	int i;
+
+	if (!mktme_available_keyids)
+		return 0;
+
+	for (i = 1; i <= mktme_nr_keyids(); i++) {
+		if (mktme_map[i].state == KEYID_AVAILABLE) {
+			mktme_map[i].state = KEYID_ASSIGNED;
+			mktme_map[i].key = key;
+			mktme_available_keyids--;
+			return i;
+		}
+	}
+	return 0;
+}
+
 enum mktme_opt_id {
 	OPT_ERROR,
 	OPT_TYPE,
@@ -43,6 +62,20 @@ static const match_table_t mktme_token = {
 	{OPT_ERROR, NULL}
 };
 
+/* Key Service Method to create a new key. Payload is preparsed. */
+int mktme_instantiate_key(struct key *key, struct key_preparsed_payload *prep)
+{
+	unsigned long flags;
+	int keyid;
+
+	spin_lock_irqsave(&mktme_lock, flags);
+	keyid = mktme_reserve_keyid(key);
+	spin_unlock_irqrestore(&mktme_lock, flags);
+	if (!keyid)
+		return -ENOKEY;
+	return 0;
+}
+
 /* Make sure arguments are correct for the TYPE of key requested */
 static int mktme_check_options(u32 *payload, unsigned long token_mask,
 			       enum mktme_type type, enum mktme_alg alg)
@@ -163,6 +196,7 @@ struct key_type key_type_mktme = {
 	.name		= "mktme",
 	.preparse	= mktme_preparse_payload,
 	.free_preparse	= mktme_free_preparsed_payload,
+	.instantiate	= mktme_instantiate_key,
 	.describe	= user_describe,
 };
 
-- 
2.21.0