From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6E366C11D25 for ; Thu, 20 Feb 2020 20:51:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 465FC20679 for ; Thu, 20 Feb 2020 20:51:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729144AbgBTUvz (ORCPT ); Thu, 20 Feb 2020 15:51:55 -0500 Received: from out03.mta.xmission.com ([166.70.13.233]:34144 "EHLO out03.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728936AbgBTUvy (ORCPT ); Thu, 20 Feb 2020 15:51:54 -0500 Received: from in01.mta.xmission.com ([166.70.13.51]) by out03.mta.xmission.com with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1j4snZ-0006Pe-Ka; Thu, 20 Feb 2020 13:51:53 -0700 Received: from ip68-227-160-95.om.om.cox.net ([68.227.160.95] helo=x220.xmission.com) by in01.mta.xmission.com with esmtpsa (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.87) (envelope-from ) id 1j4snY-0005Ze-Lt; Thu, 20 Feb 2020 13:51:53 -0700 From: ebiederm@xmission.com (Eric W. Biederman) To: Linus Torvalds Cc: Al Viro , LKML , Kernel Hardening , Linux API , Linux FS Devel , Linux Security Module , Akinobu Mita , Alexey Dobriyan , Andrew Morton , Andy Lutomirski , Daniel Micay , Djalal Harouni , "Dmitry V . Levin" , Greg Kroah-Hartman , Ingo Molnar , "J . Bruce Fields" , Jeff Layton , Jonathan Corbet , Kees Cook , Oleg Nesterov , Solar Designer References: <20200210150519.538333-8-gladkov.alexey@gmail.com> <87v9odlxbr.fsf@x220.int.ebiederm.org> <20200212144921.sykucj4mekcziicz@comp-core-i7-2640m-0182e6> <87tv3vkg1a.fsf@x220.int.ebiederm.org> <87v9obipk9.fsf@x220.int.ebiederm.org> <20200212200335.GO23230@ZenIV.linux.org.uk> <20200212203833.GQ23230@ZenIV.linux.org.uk> <20200212204124.GR23230@ZenIV.linux.org.uk> <87lfp7h422.fsf@x220.int.ebiederm.org> <87pnejf6fz.fsf@x220.int.ebiederm.org> <871rqpaswu.fsf_-_@x220.int.ebiederm.org> Date: Thu, 20 Feb 2020 14:49:53 -0600 In-Reply-To: <871rqpaswu.fsf_-_@x220.int.ebiederm.org> (Eric W. Biederman's message of "Thu, 20 Feb 2020 14:46:25 -0600") Message-ID: <87blpt9e6m.fsf_-_@x220.int.ebiederm.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-XM-SPF: eid=1j4snY-0005Ze-Lt;;;mid=<87blpt9e6m.fsf_-_@x220.int.ebiederm.org>;;;hst=in01.mta.xmission.com;;;ip=68.227.160.95;;;frm=ebiederm@xmission.com;;;spf=neutral X-XM-AID: U2FsdGVkX1+0jzXheB+9rojm9OHQfM0H+L/hnF6cm6M= X-SA-Exim-Connect-IP: 68.227.160.95 X-SA-Exim-Mail-From: ebiederm@xmission.com Subject: [PATCH 4/7] proc: Use d_invalidate in proc_prune_siblings_dcache X-SA-Exim-Version: 4.2.1 (built Thu, 05 May 2016 13:38:54 -0600) X-SA-Exim-Scanned: Yes (on in01.mta.xmission.com) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The function d_prune_aliases has the problem that it will only prune aliases thare are completely unused. It will not remove aliases for the dcache or even think of removing mounts from the dcache. For that behavior d_invalidate is needed. To use d_invalidate replace d_prune_aliases with d_find_alias followed by d_invalidate and dput. This is safe and complete because no inode in proc has any hardlinks or aliases. To make this behavior change clear rename proc_prune_siblings_dache proc_invalidate_siblings_dcache, and rename proc_sys_prune_dcache proc_sys_invalidate_dcache. Signed-off-by: "Eric W. Biederman" --- fs/proc/inode.c | 9 +++++++-- fs/proc/internal.h | 2 +- fs/proc/proc_sysctl.c | 8 ++++---- 3 files changed, 12 insertions(+), 7 deletions(-) diff --git a/fs/proc/inode.c b/fs/proc/inode.c index 38a7baa41aba..c4528c419876 100644 --- a/fs/proc/inode.c +++ b/fs/proc/inode.c @@ -103,12 +103,13 @@ void __init proc_init_kmemcache(void) BUILD_BUG_ON(sizeof(struct proc_dir_entry) >= SIZEOF_PDE); } -void proc_prune_siblings_dcache(struct hlist_head *inodes, spinlock_t *lock) +void proc_invalidate_siblings_dcache(struct hlist_head *inodes, spinlock_t *lock) { struct inode *inode; struct proc_inode *ei; struct hlist_node *node; struct super_block *sb; + struct dentry *dentry; for (;;) { rcu_read_lock(); @@ -135,7 +136,11 @@ void proc_prune_siblings_dcache(struct hlist_head *inodes, spinlock_t *lock) continue; } - d_prune_aliases(inode); + dentry = d_find_alias(inode); + if (dentry) { + d_invalidate(dentry); + dput(dentry); + } iput(inode); deactivate_super(sb); } diff --git a/fs/proc/internal.h b/fs/proc/internal.h index ba9a991824a5..fd470172675f 100644 --- a/fs/proc/internal.h +++ b/fs/proc/internal.h @@ -210,7 +210,7 @@ extern const struct inode_operations proc_pid_link_inode_operations; extern const struct super_operations proc_sops; void proc_init_kmemcache(void); -void proc_prune_siblings_dcache(struct hlist_head *inodes, spinlock_t *lock); +void proc_invalidate_siblings_dcache(struct hlist_head *inodes, spinlock_t *lock); void set_proc_pid_nlink(void); extern struct inode *proc_get_inode(struct super_block *, struct proc_dir_entry *); extern void proc_entry_rundown(struct proc_dir_entry *); diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c index 5da9d7f7ae34..b6f5d459b087 100644 --- a/fs/proc/proc_sysctl.c +++ b/fs/proc/proc_sysctl.c @@ -267,9 +267,9 @@ static void unuse_table(struct ctl_table_header *p) complete(p->unregistering); } -static void proc_sys_prune_dcache(struct ctl_table_header *head) +static void proc_sys_invalidate_dcache(struct ctl_table_header *head) { - proc_prune_siblings_dcache(&head->inodes, &sysctl_lock); + proc_invalidate_siblings_dcache(&head->inodes, &sysctl_lock); } /* called under sysctl_lock, will reacquire if has to wait */ @@ -291,10 +291,10 @@ static void start_unregistering(struct ctl_table_header *p) spin_unlock(&sysctl_lock); } /* - * Prune dentries for unregistered sysctls: namespaced sysctls + * Invalidate dentries for unregistered sysctls: namespaced sysctls * can have duplicate names and contaminate dcache very badly. */ - proc_sys_prune_dcache(p); + proc_sys_invalidate_dcache(p); /* * do not remove from the list until nobody holds it; walking the * list in do_sysctl() relies on that. -- 2.20.1