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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id h4-20020a17090a710400b0020ae09e9724sm474301pjk.53.2022.10.13.20.54.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 13 Oct 2022 20:54:15 -0700 (PDT) Date: Thu, 13 Oct 2022 20:54:14 -0700 From: Kees Cook To: Andy Lutomirski Cc: Jann Horn , Christian Brauner , "Eric W. Biederman" , Jorge Merlino , Al Viro , Thomas Gleixner , Sebastian Andrzej Siewior , Andrew Morton , linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, John Johansen , Paul Moore , James Morris , "Serge E. Hallyn" , Stephen Smalley , Eric Paris , Richard Haines , Casey Schaufler , Xin Long , "David S. Miller" , Todd Kjos , Ondrej Mosnacek , Prashanth Prahlad , Micah Morton , Fenghua Yu , Andrei Vagin , Linux Kernel Mailing List , apparmor@lists.ubuntu.com, linux-security-module@vger.kernel.org, selinux@vger.kernel.org, linux-hardening@vger.kernel.org Subject: Re: [PATCH 1/2] fs/exec: Explicitly unshare fs_struct on exec Message-ID: <202210132052.32AE372@keescook> References: <20221006082735.1321612-1-keescook@chromium.org> <20221006082735.1321612-2-keescook@chromium.org> <20221006090506.paqjf537cox7lqrq@wittgenstein> <2032f766-1704-486b-8f24-a670c0b3cb32@app.fastmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2032f766-1704-486b-8f24-a670c0b3cb32@app.fastmail.com> X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE, SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Oct 13, 2022 at 08:18:04PM -0700, Andy Lutomirski wrote: > But seriously, this makes no sense at all. It should not be possible to exec a program and then, without ptrace, change its cwd out from under it. Do we really need to preserve this behavior? Yup, already abandoned: https://lore.kernel.org/lkml/202210061301.207A20C8E5@keescook/ -- Kees Cook