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Shutemov" X-Google-Original-From: "Kirill A. Shutemov" Received: by box.localdomain (Postfix, from userid 1000) id C65041044A6; Wed, 31 Jul 2019 18:08:16 +0300 (+03) To: Andrew Morton , x86@kernel.org, Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Borislav Petkov , Peter Zijlstra , Andy Lutomirski , David Howells Cc: Kees Cook , Dave Hansen , Kai Huang , Jacob Pan , Alison Schofield , linux-mm@kvack.org, kvm@vger.kernel.org, keyrings@vger.kernel.org, linux-kernel@vger.kernel.org, "Kirill A . Shutemov" Subject: [PATCHv2 31/59] keys/mktme: Set up a percpu_ref_count for MKTME keys Date: Wed, 31 Jul 2019 18:07:45 +0300 Message-Id: <20190731150813.26289-32-kirill.shutemov@linux.intel.com> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190731150813.26289-1-kirill.shutemov@linux.intel.com> References: <20190731150813.26289-1-kirill.shutemov@linux.intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org From: Alison Schofield The MKTME key service needs to keep usage counts on the encryption keys in order to know when it is safe to free a key for reuse. percpu_ref_count applies well here because the key service will take the initial reference and typically hold that reference while the intermediary references are get/put. The intermediaries in this case will be encrypted VMA's, Align the percpu_ref_init and percpu_ref_kill with the key service instantiate and destroy methods respectively. Signed-off-by: Alison Schofield Signed-off-by: Kirill A. Shutemov --- security/keys/mktme_keys.c | 39 +++++++++++++++++++++++++++++++++++++- 1 file changed, 38 insertions(+), 1 deletion(-) diff --git a/security/keys/mktme_keys.c b/security/keys/mktme_keys.c index 3c641f3ee794..18cb57be5193 100644 --- a/security/keys/mktme_keys.c +++ b/security/keys/mktme_keys.c @@ -8,6 +8,7 @@ #include #include #include +#include #include #include #include @@ -71,6 +72,26 @@ int mktme_keyid_from_key(struct key *key) return 0; } +struct percpu_ref *encrypt_count; +void mktme_percpu_ref_release(struct percpu_ref *ref) +{ + unsigned long flags; + int keyid; + + for (keyid = 1; keyid <= mktme_nr_keyids(); keyid++) { + if (&encrypt_count[keyid] == ref) + break; + } + if (&encrypt_count[keyid] != ref) { + pr_debug("%s: invalid ref counter\n", __func__); + return; + } + percpu_ref_exit(ref); + spin_lock_irqsave(&mktme_lock, flags); + mktme_release_keyid(keyid); + spin_unlock_irqrestore(&mktme_lock, flags); +} + enum mktme_opt_id { OPT_ERROR, OPT_TYPE, @@ -199,8 +220,10 @@ static void mktme_destroy_key(struct key *key) unsigned long flags; spin_lock_irqsave(&mktme_lock, flags); - mktme_release_keyid(keyid); + mktme_map[keyid].key = NULL; + mktme_map[keyid].state = KEYID_REF_KILLED; spin_unlock_irqrestore(&mktme_lock, flags); + percpu_ref_kill(&encrypt_count[keyid]); } /* Key Service Method to create a new key. Payload is preparsed. */ @@ -216,9 +239,15 @@ int mktme_instantiate_key(struct key *key, struct key_preparsed_payload *prep) if (!keyid) return -ENOKEY; + if (percpu_ref_init(&encrypt_count[keyid], mktme_percpu_ref_release, + 0, GFP_KERNEL)) + goto err_out; + if (!mktme_program_keyid(keyid, *payload)) return MKTME_PROG_SUCCESS; + percpu_ref_exit(&encrypt_count[keyid]); +err_out: spin_lock_irqsave(&mktme_lock, flags); mktme_release_keyid(keyid); spin_unlock_irqrestore(&mktme_lock, flags); @@ -405,10 +434,18 @@ static int __init init_mktme(void) /* Initialize first programming targets */ mktme_update_pconfig_targets(); + /* Reference counters to protect in use KeyIDs */ + encrypt_count = kvcalloc(mktme_nr_keyids() + 1, sizeof(encrypt_count[0]), + GFP_KERNEL); + if (!encrypt_count) + goto free_targets; + ret = register_key_type(&key_type_mktme); if (!ret) return ret; /* SUCCESS */ + kvfree(encrypt_count); +free_targets: free_cpumask_var(mktme_leadcpus); bitmap_free(mktme_target_map); free_cache: -- 2.21.0