From patchwork Tue Sep 15 10:49:35 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexey Kardashevskiy X-Patchwork-Id: 517816 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id CB4281401EF for ; Tue, 15 Sep 2015 20:51:05 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751640AbbIOKvE (ORCPT ); Tue, 15 Sep 2015 06:51:04 -0400 Received: from e23smtp09.au.ibm.com ([202.81.31.142]:38512 "EHLO e23smtp09.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752334AbbIOKvD (ORCPT ); Tue, 15 Sep 2015 06:51:03 -0400 Received: from /spool/local by e23smtp09.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; Tue, 15 Sep 2015 20:51:00 +1000 X-Helo: d23dlp02.au.ibm.com X-MailFrom: aik@ozlabs.ru X-RcptTo: kvm@vger.kernel.org Received: from d23relay06.au.ibm.com (d23relay06.au.ibm.com [9.185.63.219]) by d23dlp02.au.ibm.com (Postfix) with ESMTP id 54D282BB0054; Tue, 15 Sep 2015 20:50:59 +1000 (EST) Received: from d23av02.au.ibm.com (d23av02.au.ibm.com [9.190.235.138]) by d23relay06.au.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id t8FAomHC26804270; Tue, 15 Sep 2015 20:50:56 +1000 Received: from d23av02.au.ibm.com (localhost [127.0.0.1]) by d23av02.au.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id t8FAoQwY026650; Tue, 15 Sep 2015 20:50:27 +1000 Received: from ozlabs.au.ibm.com (ozlabs.au.ibm.com [9.192.253.14]) by d23av02.au.ibm.com (8.14.4/8.14.4/NCO v10.0 AVin) with ESMTP id t8FAoQ3E026267; Tue, 15 Sep 2015 20:50:26 +1000 Received: from bran.ozlabs.ibm.com (haven.au.ibm.com [9.192.254.114]) by ozlabs.au.ibm.com (Postfix) with ESMTP id 1F5BDA03E0; Tue, 15 Sep 2015 20:49:42 +1000 (AEST) Received: from ka1.ozlabs.ibm.com (ka1.ozlabs.ibm.com [10.61.145.11]) by bran.ozlabs.ibm.com (Postfix) with ESMTP id 17F22E450E; Tue, 15 Sep 2015 20:49:42 +1000 (AEST) From: Alexey Kardashevskiy To: linuxppc-dev@lists.ozlabs.org Cc: Alexey Kardashevskiy , Paul Mackerras , Alexander Graf , David Gibson , kvm-ppc@vger.kernel.org, kvm@vger.kernel.org Subject: [PATCH kernel 5/9] KVM: PPC: Account TCE-containing pages in locked_vm Date: Tue, 15 Sep 2015 20:49:35 +1000 Message-Id: <1442314179-9706-6-git-send-email-aik@ozlabs.ru> X-Mailer: git-send-email 2.4.0.rc3.8.gfb3e7d5 In-Reply-To: <1442314179-9706-1-git-send-email-aik@ozlabs.ru> References: <1442314179-9706-1-git-send-email-aik@ozlabs.ru> X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 15091510-0033-0000-0000-000002200351 Sender: kvm-ppc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm-ppc@vger.kernel.org At the moment pages used for TCE tables (in addition to pages addressed by TCEs) are not counted in locked_vm counter so a malicious userspace tool can call ioctl(KVM_CREATE_SPAPR_TCE) as many times as RLIMIT_NOFILE and lock a lot of memory. This adds counting for pages used for TCE tables. This counts the number of pages required for a table plus pages for the kvmppc_spapr_tce_table struct (TCE table descriptor) itself. This does not change the amount of (de)allocated memory. Signed-off-by: Alexey Kardashevskiy --- arch/powerpc/kvm/book3s_64_vio.c | 51 +++++++++++++++++++++++++++++++++++++++- 1 file changed, 50 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/kvm/book3s_64_vio.c b/arch/powerpc/kvm/book3s_64_vio.c index 9526c34..b70787d 100644 --- a/arch/powerpc/kvm/book3s_64_vio.c +++ b/arch/powerpc/kvm/book3s_64_vio.c @@ -45,13 +45,56 @@ static long kvmppc_stt_npages(unsigned long window_size) * sizeof(u64), PAGE_SIZE) / PAGE_SIZE; } +static long kvmppc_account_memlimit(long npages, bool inc) +{ + long ret = 0; + const long bytes = sizeof(struct kvmppc_spapr_tce_table) + + (abs(npages) * sizeof(struct page *)); + const long stt_pages = ALIGN(bytes, PAGE_SIZE) / PAGE_SIZE; + + if (!current || !current->mm) + return ret; /* process exited */ + + npages += stt_pages; + + down_write(¤t->mm->mmap_sem); + + if (inc) { + long locked, lock_limit; + + locked = current->mm->locked_vm + npages; + lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT; + if (locked > lock_limit && !capable(CAP_IPC_LOCK)) + ret = -ENOMEM; + else + current->mm->locked_vm += npages; + } else { + if (npages > current->mm->locked_vm) + npages = current->mm->locked_vm; + + current->mm->locked_vm -= npages; + } + + pr_debug("[%d] RLIMIT_MEMLOCK KVM %c%ld %ld/%ld%s\n", current->pid, + inc ? '+' : '-', + npages << PAGE_SHIFT, + current->mm->locked_vm << PAGE_SHIFT, + rlimit(RLIMIT_MEMLOCK), + ret ? " - exceeded" : ""); + + up_write(¤t->mm->mmap_sem); + + return ret; +} + static void release_spapr_tce_table(struct rcu_head *head) { struct kvmppc_spapr_tce_table *stt = container_of(head, struct kvmppc_spapr_tce_table, rcu); int i; + long npages = kvmppc_stt_npages(stt->window_size); - for (i = 0; i < kvmppc_stt_npages(stt->window_size); i++) + for (i = 0; i < npages; i++) __free_page(stt->pages[i]); kfree(stt); @@ -89,6 +132,7 @@ static int kvm_spapr_tce_release(struct inode *inode, struct file *filp) kvm_put_kvm(stt->kvm); + kvmppc_account_memlimit(kvmppc_stt_npages(stt->window_size), false); call_rcu(&stt->rcu, release_spapr_tce_table); return 0; @@ -114,6 +158,11 @@ long kvm_vm_ioctl_create_spapr_tce(struct kvm *kvm, } npages = kvmppc_stt_npages(args->window_size); + ret = kvmppc_account_memlimit(npages, true); + if (ret) { + stt = NULL; + goto fail; + } stt = kzalloc(sizeof(*stt) + npages * sizeof(struct page *), GFP_KERNEL);