From patchwork Thu Feb 20 20:49:53 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Eric W. Biederman" X-Patchwork-Id: 11395023 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id B95DA92A for ; Thu, 20 Feb 2020 20:52:08 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id F2C8920679 for ; Thu, 20 Feb 2020 20:52:07 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org F2C8920679 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=xmission.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kernel-hardening-return-17863-patchwork-kernel-hardening=patchwork.kernel.org@lists.openwall.com Received: (qmail 1707 invoked by uid 550); 20 Feb 2020 20:52:06 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Delivered-To: mailing list kernel-hardening@lists.openwall.com Received: (qmail 1670 invoked from network); 20 Feb 2020 20:52:05 -0000 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 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 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on sa06.xmission.com X-Spam-Level: ** X-Spam-Status: No, score=2.5 required=8.0 tests=ALL_TRUSTED,BAYES_50, DCC_CHECK_NEGATIVE,T_TooManySym_01,XMGappySubj_01,XMNoVowels,XMSubLong autolearn=disabled version=3.4.2 X-Spam-Report: * -1.0 ALL_TRUSTED Passed through trusted hosts only via SMTP * 0.8 BAYES_50 BODY: Bayes spam probability is 40 to 60% * [score: 0.4982] * 0.7 XMSubLong Long Subject * 1.5 XMNoVowels Alpha-numberic number with no vowels * 0.5 XMGappySubj_01 Very gappy subject * -0.0 DCC_CHECK_NEGATIVE Not listed in DCC * [sa06 1397; Body=1 Fuz1=1 Fuz2=1] * 0.0 T_TooManySym_01 4+ unique symbols in subject X-Spam-DCC: XMission; sa06 1397; Body=1 Fuz1=1 Fuz2=1 X-Spam-Combo: **;Linus Torvalds X-Spam-Relay-Country: X-Spam-Timing: total 538 ms - load_scoreonly_sql: 0.05 (0.0%), signal_user_changed: 3.3 (0.6%), b_tie_ro: 2.3 (0.4%), parse: 1.02 (0.2%), extract_message_metadata: 11 (2.1%), get_uri_detail_list: 1.95 (0.4%), tests_pri_-1000: 14 (2.7%), tests_pri_-950: 1.26 (0.2%), tests_pri_-900: 1.04 (0.2%), tests_pri_-90: 29 (5.4%), check_bayes: 28 (5.2%), b_tokenize: 11 (2.0%), b_tok_get_all: 8 (1.5%), b_comp_prob: 2.5 (0.5%), b_tok_touch_all: 4.2 (0.8%), b_finish: 0.66 (0.1%), tests_pri_0: 466 (86.5%), check_dkim_signature: 0.60 (0.1%), check_dkim_adsp: 2.5 (0.5%), poll_dns_idle: 0.79 (0.1%), tests_pri_10: 2.1 (0.4%), tests_pri_500: 6 (1.2%), rewrite_mail: 0.00 (0.0%) Subject: [PATCH 4/7] proc: Use d_invalidate in proc_prune_siblings_dcache X-Spam-Flag: No 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) 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.