From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.1 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A0628C433F5 for ; Fri, 3 Sep 2021 08:56:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7C53B60E77 for ; Fri, 3 Sep 2021 08:56:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1348546AbhICI5a (ORCPT ); Fri, 3 Sep 2021 04:57:30 -0400 Received: from pegase2.c-s.fr ([93.17.235.10]:40695 "EHLO pegase2.c-s.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1348461AbhICI51 (ORCPT ); Fri, 3 Sep 2021 04:57:27 -0400 Received: from localhost (mailhub3.si.c-s.fr [172.26.127.67]) by localhost (Postfix) with ESMTP id 4H1BVL6bMpz9sTr; Fri, 3 Sep 2021 10:56:26 +0200 (CEST) X-Virus-Scanned: amavisd-new at c-s.fr Received: from pegase2.c-s.fr ([172.26.127.65]) by localhost (pegase2.c-s.fr [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id K3RKjrD-w8d1; Fri, 3 Sep 2021 10:56:26 +0200 (CEST) Received: from messagerie.si.c-s.fr (messagerie.si.c-s.fr [192.168.25.192]) by pegase2.c-s.fr (Postfix) with ESMTP id 4H1BVL5L22z9sTN; Fri, 3 Sep 2021 10:56:26 +0200 (CEST) Received: from localhost (localhost [127.0.0.1]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 93B3B8B8D5; Fri, 3 Sep 2021 10:56:26 +0200 (CEST) X-Virus-Scanned: amavisd-new at c-s.fr Received: from messagerie.si.c-s.fr ([127.0.0.1]) by localhost (messagerie.si.c-s.fr [127.0.0.1]) (amavisd-new, port 10023) with ESMTP id DZQ-ShpYtKAd; Fri, 3 Sep 2021 10:56:26 +0200 (CEST) Received: from [192.168.4.90] (unknown [192.168.4.90]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 0DFFA8B764; Fri, 3 Sep 2021 10:56:26 +0200 (CEST) Subject: Re: [PATCH v2 3/5] signal: Add unsafe_copy_siginfo_to_user() To: "Eric W. Biederman" Cc: Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org References: <87mtoux1hi.fsf@disp2133> From: Christophe Leroy Message-ID: <2715792c-eb10-eeb8-3d49-24486abe953b@csgroup.eu> Date: Fri, 3 Sep 2021 10:56:14 +0200 User-Agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.13.0 MIME-Version: 1.0 In-Reply-To: <87mtoux1hi.fsf@disp2133> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: fr Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Le 02/09/2021 à 20:43, Eric W. Biederman a écrit : > Christophe Leroy writes: > >> In the same spirit as commit fb05121fd6a2 ("signal: Add >> unsafe_get_compat_sigset()"), implement an 'unsafe' version of >> copy_siginfo_to_user() in order to use it within user access blocks. >> >> For that, also add an 'unsafe' version of clear_user(). > > Looking at your use cases you need the 32bit compat version of this > as well. > > The 32bit compat version is too complicated to become a macro, so I > don't think you can make this work correctly for the 32bit compat case. When looking into patch 5/5 that you nacked, I think you missed the fact that we keep using copy_siginfo_to_user32() as it for the 32 bit compat case. > > Probably-Not-by: "Eric W. Biederman" > > Eric > >> Signed-off-by: Christophe Leroy >> --- >> include/linux/signal.h | 15 +++++++++++++++ >> include/linux/uaccess.h | 1 + >> kernel/signal.c | 5 ----- >> 3 files changed, 16 insertions(+), 5 deletions(-) >> >> diff --git a/include/linux/signal.h b/include/linux/signal.h >> index 3454c7ff0778..659bd43daf10 100644 >> --- a/include/linux/signal.h >> +++ b/include/linux/signal.h >> @@ -35,6 +35,21 @@ static inline void copy_siginfo_to_external(siginfo_t *to, >> int copy_siginfo_to_user(siginfo_t __user *to, const kernel_siginfo_t *from); >> int copy_siginfo_from_user(kernel_siginfo_t *to, const siginfo_t __user *from); >> >> +static __always_inline char __user *si_expansion(const siginfo_t __user *info) >> +{ >> + return ((char __user *)info) + sizeof(struct kernel_siginfo); >> +} >> + >> +#define unsafe_copy_siginfo_to_user(to, from, label) do { \ >> + siginfo_t __user *__ucs_to = to; \ >> + const kernel_siginfo_t *__ucs_from = from; \ >> + char __user *__ucs_expansion = si_expansion(__ucs_to); \ >> + \ >> + unsafe_copy_to_user(__ucs_to, __ucs_from, \ >> + sizeof(struct kernel_siginfo), label); \ >> + unsafe_clear_user(__ucs_expansion, SI_EXPANSION_SIZE, label); \ >> +} while (0) >> + >> enum siginfo_layout { >> SIL_KILL, >> SIL_TIMER, >> diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h >> index c05e903cef02..37073caac474 100644 >> --- a/include/linux/uaccess.h >> +++ b/include/linux/uaccess.h >> @@ -398,6 +398,7 @@ long strnlen_user_nofault(const void __user *unsafe_addr, long count); >> #define unsafe_put_user(x,p,e) unsafe_op_wrap(__put_user(x,p),e) >> #define unsafe_copy_to_user(d,s,l,e) unsafe_op_wrap(__copy_to_user(d,s,l),e) >> #define unsafe_copy_from_user(d,s,l,e) unsafe_op_wrap(__copy_from_user(d,s,l),e) >> +#define unsafe_clear_user(d, l, e) unsafe_op_wrap(__clear_user(d, l), e) >> static inline unsigned long user_access_save(void) { return 0UL; } >> static inline void user_access_restore(unsigned long flags) { } >> #endif >> diff --git a/kernel/signal.c b/kernel/signal.c >> index a3229add4455..83b5971e4304 100644 >> --- a/kernel/signal.c >> +++ b/kernel/signal.c >> @@ -3261,11 +3261,6 @@ enum siginfo_layout siginfo_layout(unsigned sig, int si_code) >> return layout; >> } >> >> -static inline char __user *si_expansion(const siginfo_t __user *info) >> -{ >> - return ((char __user *)info) + sizeof(struct kernel_siginfo); >> -} >> - >> int copy_siginfo_to_user(siginfo_t __user *to, const kernel_siginfo_t *from) >> { >> char __user *expansion = si_expansion(to);