From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on inbox.vuxu.org X-Spam-Level: X-Spam-Status: No, score=-3.3 required=5.0 tests=MAILING_LIST_MULTI, RCVD_IN_DNSWL_MED,RCVD_IN_MSPIKE_H3,RCVD_IN_MSPIKE_WL autolearn=ham autolearn_force=no version=3.4.4 Received: (qmail 24339 invoked from network); 13 Oct 2020 15:25:00 -0000 Received: from mother.openwall.net (195.42.179.200) by inbox.vuxu.org with ESMTPUTF8; 13 Oct 2020 15:25:00 -0000 Received: (qmail 13607 invoked by uid 550); 13 Oct 2020 15:24:57 -0000 Mailing-List: contact musl-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Reply-To: musl@lists.openwall.com Received: (qmail 13589 invoked from network); 13 Oct 2020 15:24:57 -0000 MIME-Version: 1.0 Date: Tue, 13 Oct 2020 18:24:45 +0300 From: Alexey Izbyshev To: musl@lists.openwall.com In-Reply-To: <20201013024737.GB7816@voyager> References: <93cbaeffbc860a145843e0380058c50e@ispras.ru> <20201012145549.GG17637@brightrain.aerifal.cx> <20201013024737.GB7816@voyager> User-Agent: Roundcube Webmail/1.4.4 Message-ID: <208f256649f23621ada37409eb02ff86@ispras.ru> X-Sender: izbyshev@ispras.ru Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [musl] Calling setxid() in a vfork()-child On 2020-10-13 05:47, Markus Wichmann wrote: > If dropping privileges is all you want, then posix_spawn() has a flag > for that. And if you are foregoing portability anyway by doing anything > between vfork() and execve(), might as well use clone() and do it > properly. > What do you mean by "do it properly"? Unless you mean doing syscalls, it seems that I'd have the same issues with clone() (with CLONE_VFORK, since I'm trying to avoid copying of page tables) as I do with vfork(). Namely, I'd still have to care about signals, and I wouldn't be able to safely call setxid() (and, frankly, anything else from a C library if we want a solution that's, while being Linux-specific, still portable across C libraries).