linux-kernel - [PATCHv2 27/59] keys/mktme: Destroy MKTME keys

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Date:   Wed, 31 Jul 2019 18:07:41 +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 27/59] keys/mktme: Destroy MKTME keys

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

Destroy is a method invoked by the kernel key service when a
userspace key is being removed. (invalidate, revoke, timeout).

During destroy, MKTME wil returned the hardware KeyID to the pool
of available keyids.

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 | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/security/keys/mktme_keys.c b/security/keys/mktme_keys.c
index beca852db01a..10fcdbf5a08f 100644
--- a/security/keys/mktme_keys.c
+++ b/security/keys/mktme_keys.c
@@ -50,6 +50,23 @@ int mktme_reserve_keyid(struct key *key)
 	return 0;
 }
 
+static void mktme_release_keyid(int keyid)
+{
+	 mktme_map[keyid].state = KEYID_AVAILABLE;
+	 mktme_available_keyids++;
+}
+
+int mktme_keyid_from_key(struct key *key)
+{
+	int i;
+
+	for (i = 1; i <= mktme_nr_keyids(); i++) {
+		if (mktme_map[i].key == key)
+			return i;
+	}
+	return 0;
+}
+
 enum mktme_opt_id {
 	OPT_ERROR,
 	OPT_TYPE,
@@ -62,6 +79,17 @@ static const match_table_t mktme_token = {
 	{OPT_ERROR, NULL}
 };
 
+/* Key Service Method called when a Userspace Key is garbage collected. */
+static void mktme_destroy_key(struct key *key)
+{
+	int keyid = mktme_keyid_from_key(key);
+	unsigned long flags;
+
+	spin_lock_irqsave(&mktme_lock, flags);
+	mktme_release_keyid(keyid);
+	spin_unlock_irqrestore(&mktme_lock, flags);
+}
+
 /* Key Service Method to create a new key. Payload is preparsed. */
 int mktme_instantiate_key(struct key *key, struct key_preparsed_payload *prep)
 {
@@ -198,6 +226,7 @@ struct key_type key_type_mktme = {
 	.free_preparse	= mktme_free_preparsed_payload,
 	.instantiate	= mktme_instantiate_key,
 	.describe	= user_describe,
+	.destroy	= mktme_destroy_key,
 };
 
 static int __init init_mktme(void)
-- 
2.21.0