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[192.55.52.115]) by mx.google.com with ESMTPS id d3si22507173pfc.278.2019.05.08.07.44.46 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 08 May 2019 07:44:46 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of kirill.shutemov@linux.intel.com designates 192.55.52.115 as permitted sender) client-ip=192.55.52.115; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of kirill.shutemov@linux.intel.com designates 192.55.52.115 as permitted sender) smtp.mailfrom=kirill.shutemov@linux.intel.com; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=intel.com X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga001.jf.intel.com ([10.7.209.18]) by fmsmga103.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 08 May 2019 07:44:45 -0700 X-ExtLoop1: 1 Received: from black.fi.intel.com ([10.237.72.28]) by orsmga001.jf.intel.com with ESMTP; 08 May 2019 07:44:40 -0700 Received: by black.fi.intel.com (Postfix, from userid 1000) id 297B6B2F; Wed, 8 May 2019 17:44:30 +0300 (EEST) From: "Kirill A. Shutemov" 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: [PATCH, RFC 30/62] keys/mktme: Set up a percpu_ref_count for MKTME keys Date: Wed, 8 May 2019 17:43:50 +0300 Message-Id: <20190508144422.13171-31-kirill.shutemov@linux.intel.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190508144422.13171-1-kirill.shutemov@linux.intel.com> References: <20190508144422.13171-1-kirill.shutemov@linux.intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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 are the 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 | 40 +++++++++++++++++++++++++++++++++++++- 1 file changed, 39 insertions(+), 1 deletion(-) diff --git a/security/keys/mktme_keys.c b/security/keys/mktme_keys.c index f70533b1a7fd..496b5c1b7461 100644 --- a/security/keys/mktme_keys.c +++ b/security/keys/mktme_keys.c @@ -8,6 +8,7 @@ #include #include #include +#include #include #include #include @@ -80,6 +81,26 @@ 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_map_lock, flags); + mktme_release_keyid(keyid); + spin_unlock_irqrestore(&mktme_map_lock, flags); +} + enum mktme_opt_id { OPT_ERROR, OPT_TYPE, @@ -225,7 +246,10 @@ static int mktme_program_keyid(int keyid, struct mktme_payload *payload) /* Key Service Method called when a Userspace Key is garbage collected. */ static void mktme_destroy_key(struct key *key) { - mktme_release_keyid(mktme_keyid_from_key(key)); + int keyid = mktme_keyid_from_key(key); + + mktme_map->key[keyid] = (void *)-1; + percpu_ref_kill(&encrypt_count[keyid]); } /* Key Service Method to create a new key. Payload is preparsed. */ @@ -241,9 +265,15 @@ 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); @@ -447,10 +477,18 @@ 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: -- 2.20.1