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[209.85.167.43]) by smtp.gmail.com with ESMTPSA id k28sm16089lfj.33.2019.09.04.14.42.38 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 04 Sep 2019 14:42:38 -0700 (PDT) Received: by mail-lf1-f43.google.com with SMTP id c12so217826lfh.5 for ; Wed, 04 Sep 2019 14:42:38 -0700 (PDT) X-Received: by 2002:a05:6512:512:: with SMTP id o18mr154625lfb.170.1567633024273; Wed, 04 Sep 2019 14:37:04 -0700 (PDT) MIME-Version: 1.0 References: <20190904201933.10736-1-cyphar@cyphar.com> <20190904201933.10736-11-cyphar@cyphar.com> In-Reply-To: From: Linus Torvalds Date: Wed, 4 Sep 2019 14:36:48 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v12 10/12] namei: aggressively check for nd->root escape on ".." resolution To: Aleksa Sarai Cc: Al Viro , Jeff Layton , "J. Bruce Fields" , Arnd Bergmann , David Howells , Shuah Khan , Shuah Khan , Ingo Molnar , Peter Zijlstra , Christian Brauner , Jann Horn , Kees Cook , Eric Biederman , Andy Lutomirski , Andrew Morton , Alexei Starovoitov , Tycho Andersen , David Drysdale , Chanho Min , Oleg Nesterov , Rasmus Villemoes , Alexander Shishkin , Jiri Olsa , Namhyung Kim , Aleksa Sarai , Linux Containers , alpha , Linux API , linux-arch , Linux ARM , linux-fsdevel , linux-ia64@vger.kernel.org, Linux List Kernel Mailing , "open list:KERNEL SELFTEST FRAMEWORK" , linux-m68k , linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390 , Linux-sh list , linux-xtensa@linux-xtensa.org, sparclinux@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Sender: linux-kselftest-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org On Wed, Sep 4, 2019 at 2:35 PM Linus Torvalds wrote: > > On Wed, Sep 4, 2019 at 2:09 PM Linus Torvalds > wrote: > > > > So you'd have three stages: > > > > 1) ".." always returns -EXDEV > > > > 2) ".." returns -EXDEV if there was a concurrent rename/mount > > > > 3) ".." returns -EXDEV if there was a concurrent rename/mount and we > > reset the sequence numbers and check if you escaped. > > In fact, I wonder if this should return -EAGAIN instead - to say that > "retrying may work". And here "this" was meant to be "case 2" - I was moving the quoted text around and didn't fix my wording, so now it is ambiguous or implies #3, which would be crazy. Sorry for the confusion, Linus