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[209.85.208.41]) by smtp.gmail.com with ESMTPSA id d9sm89599edp.97.2020.02.20.14.49.22 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 20 Feb 2020 14:49:22 -0800 (PST) Received: by mail-ed1-f41.google.com with SMTP id v28so35639708edw.12 for ; Thu, 20 Feb 2020 14:49:22 -0800 (PST) X-Received: by 2002:a2e:88c5:: with SMTP id a5mr20465844ljk.201.1582238633679; Thu, 20 Feb 2020 14:43:53 -0800 (PST) MIME-Version: 1.0 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> <87blpt9e6m.fsf_-_@x220.int.ebiederm.org> In-Reply-To: <87blpt9e6m.fsf_-_@x220.int.ebiederm.org> From: Linus Torvalds Date: Thu, 20 Feb 2020 14:43:38 -0800 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH 4/7] proc: Use d_invalidate in proc_prune_siblings_dcache To: "Eric W. Biederman" 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 Content-Type: text/plain; charset="UTF-8" Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: On Thu, Feb 20, 2020 at 12:51 PM Eric W. Biederman wrote: > > 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. Are you sure you can't create them some way? This makes em go "what if we had multiple dentries associated with that inode?" Then the code would just invalidate the first one. I guess we don't have export_operations or anything like that, but this makes me worry... Linus