From patchwork Thu Sep 20 04:41:05 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Deepa Dinamani X-Patchwork-Id: 10606841 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id B6C0914BD for ; Thu, 20 Sep 2018 04:53:28 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id A580F2873B for ; Thu, 20 Sep 2018 04:53:28 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 99AA6287CD; Thu, 20 Sep 2018 04:53:28 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FROM,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id DF65B2873B for ; Thu, 20 Sep 2018 04:53:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731358AbeITKeb (ORCPT ); Thu, 20 Sep 2018 06:34:31 -0400 Received: from mail-pg1-f195.google.com ([209.85.215.195]:33081 "EHLO mail-pg1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726028AbeITKea (ORCPT ); Thu, 20 Sep 2018 06:34:30 -0400 Received: by mail-pg1-f195.google.com with SMTP id y18-v6so507021pge.0; Wed, 19 Sep 2018 21:53:02 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=HQqqRygxhBuiyPpIMUlXQTKBkiwovKQLqXMPfKz9M1I=; b=FmXugEkf8iGJAfaIrRMuR1Zd+vm2g3XLIPNsJG4pbfLQQKW4CFy3O9Ax3aSLIJTOc6 oakDZwdRpCZz7qbAiAXFzL8XuqNpyNBfpufSTBZbLJ3ZDORbG2M9sQ0ba/7M8EsYW5E6 PLswL7XjgZ3IZp0bu1H1EgBtLVuookx1KHt079FDbTAEDwGnhnLHsllyUXAgVO+VJ9Tc MsB1auAyr/buxEUIpPlSeKzx0ZZxHDPWDktPR1qaozpu/eOulX/WSvEv3UuM3hg0O7cB GbtHImZVAqLQWnB8s4rj7Bc70JQtUfKq6dsXTEjBdfVDSoGMP+o4DY/mBfYyf93YcGFV pxZw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=HQqqRygxhBuiyPpIMUlXQTKBkiwovKQLqXMPfKz9M1I=; b=VVcAn1Ci6AR7L3uAgm3CwsdE/chPRAxLfTmCwVG+XZ7IQvCdGAdTv00U7wgYNdv7CL mAbadjltb7/AS6KRIHDJvRK03mcHpDDMC9YqDQHjN4ftOk4MNc0eSGnqXf6cVVt9VQC8 m7TN6W+/xzLJ2NRHoXfhdrRw7lo41z5y5EqZrc7BCHOUcBK9rsCPaTyvPwECGWD1iaSA JrlSOZSHv25g2P4CSqYBua3Rn9eu//9TSwAa3ZjE87nZqnb4ahCNmspsTUV0DzfffqgW wLvHqR96QdrVqYPp7gbPwEU3Jw5ubONPWkQNz8tSB1OpZ8r99lf76bIbDSHJsmVS4qv9 sT3g== X-Gm-Message-State: APzg51AgXynSesLuLQ70OIGtMUCULD/ecyPASafoAHiFTE1IAHcK20se K7CVFGmsxJuuzfAmIxhHKzc= X-Google-Smtp-Source: ANB0VdYU+bAJC0bQDFXd7sr3okvSR2WCfYAXjGYnbmJOJHXCn/9HfH3n4239OZzHWQe6oiHfYx9nqQ== X-Received: by 2002:a62:2904:: with SMTP id p4-v6mr17137591pfp.128.1537419181584; Wed, 19 Sep 2018 21:53:01 -0700 (PDT) Received: from deepa-ubuntu.lan (c-67-170-212-194.hsd1.ca.comcast.net. [67.170.212.194]) by smtp.gmail.com with ESMTPSA id d66-v6sm39209705pfd.121.2018.09.19.21.53.00 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 19 Sep 2018 21:53:01 -0700 (PDT) From: Deepa Dinamani To: viro@zeniv.linux.org.uk, tglx@linutronix.de, linux-kernel@vger.kernel.org Cc: arnd@arndb.de, y2038@lists.linaro.org, linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org, linux-aio@kvack.org Subject: [PATCH v4 2/5] signal: Add restore_user_sigmask() Date: Wed, 19 Sep 2018 21:41:05 -0700 Message-Id: <20180920044108.6606-3-deepa.kernel@gmail.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20180920044108.6606-1-deepa.kernel@gmail.com> References: <20180920044108.6606-1-deepa.kernel@gmail.com> Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Refactor the logic to restore the sigmask before the syscall returns into an api. This is useful for versions of syscalls that pass in the sigmask and expect the current->sigmask to be changed during the execution and restored after the execution of the syscall. With the advent of new y2038 syscalls in the subsequent patches, we add two more new versions of the syscalls (for pselect, ppoll and io_pgetevents) in addition to the existing native and compat versions. Adding such an api reduces the logic that would need to be replicated otherwise. Signed-off-by: Deepa Dinamani --- fs/aio.c | 29 +++++--------------- fs/eventpoll.c | 30 ++------------------- fs/select.c | 60 ++++++------------------------------------ include/linux/signal.h | 2 ++ kernel/signal.c | 33 +++++++++++++++++++++++ 5 files changed, 51 insertions(+), 103 deletions(-) diff --git a/fs/aio.c b/fs/aio.c index 67e5b1f6fb0f..b81c216534d6 100644 --- a/fs/aio.c +++ b/fs/aio.c @@ -2111,18 +2111,9 @@ SYSCALL_DEFINE6(io_pgetevents, return ret; ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &ts : NULL); - if (signal_pending(current)) { - if (ksig.sigmask) { - current->saved_sigmask = sigsaved; - set_restore_sigmask(); - } - - if (!ret) - ret = -ERESTARTNOHAND; - } else { - if (ksig.sigmask) - sigprocmask(SIG_SETMASK, &sigsaved, NULL); - } + restore_user_sigmask(ksig.sigmask, &sigsaved); + if (signal_pending(current) && !ret) + ret = -ERESTARTNOHAND; return ret; } @@ -2176,17 +2167,9 @@ COMPAT_SYSCALL_DEFINE6(io_pgetevents, return ret; ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &t : NULL); - if (signal_pending(current)) { - if (ksig.sigmask) { - current->saved_sigmask = sigsaved; - set_restore_sigmask(); - } - if (!ret) - ret = -ERESTARTNOHAND; - } else { - if (ksig.sigmask) - sigprocmask(SIG_SETMASK, &sigsaved, NULL); - } + restore_user_sigmask(ksig.sigmask, &sigsaved); + if (signal_pending(current) && !ret) + ret = -ERESTARTNOHAND; return ret; } diff --git a/fs/eventpoll.c b/fs/eventpoll.c index 2d86eeba837b..8a5a1010886b 100644 --- a/fs/eventpoll.c +++ b/fs/eventpoll.c @@ -2229,20 +2229,7 @@ SYSCALL_DEFINE6(epoll_pwait, int, epfd, struct epoll_event __user *, events, error = do_epoll_wait(epfd, events, maxevents, timeout); - /* - * If we changed the signal mask, we need to restore the original one. - * In case we've got a signal while waiting, we do not restore the - * signal mask yet, and we allow do_signal() to deliver the signal on - * the way back to userspace, before the signal mask is restored. - */ - if (sigmask) { - if (error == -EINTR) { - memcpy(¤t->saved_sigmask, &sigsaved, - sizeof(sigsaved)); - set_restore_sigmask(); - } else - set_current_blocked(&sigsaved); - } + restore_user_sigmask(sigmask, &sigsaved); return error; } @@ -2267,20 +2254,7 @@ COMPAT_SYSCALL_DEFINE6(epoll_pwait, int, epfd, err = do_epoll_wait(epfd, events, maxevents, timeout); - /* - * If we changed the signal mask, we need to restore the original one. - * In case we've got a signal while waiting, we do not restore the - * signal mask yet, and we allow do_signal() to deliver the signal on - * the way back to userspace, before the signal mask is restored. - */ - if (sigmask) { - if (err == -EINTR) { - memcpy(¤t->saved_sigmask, &sigsaved, - sizeof(sigsaved)); - set_restore_sigmask(); - } else - set_current_blocked(&sigsaved); - } + restore_user_sigmask(sigmask, &sigsaved); return err; } diff --git a/fs/select.c b/fs/select.c index 65c78b4147a2..eb9132520197 100644 --- a/fs/select.c +++ b/fs/select.c @@ -724,19 +724,7 @@ static long do_pselect(int n, fd_set __user *inp, fd_set __user *outp, ret = core_sys_select(n, inp, outp, exp, to); ret = poll_select_copy_remaining(&end_time, tsp, 0, ret); - if (ret == -ERESTARTNOHAND) { - /* - * Don't restore the signal mask yet. Let do_signal() deliver - * the signal on the way back to userspace, before the signal - * mask is restored. - */ - if (sigmask) { - memcpy(¤t->saved_sigmask, &sigsaved, - sizeof(sigsaved)); - set_restore_sigmask(); - } - } else if (sigmask) - sigprocmask(SIG_SETMASK, &sigsaved, NULL); + restore_user_sigmask(sigmask, &sigsaved); return ret; } @@ -1060,21 +1048,11 @@ SYSCALL_DEFINE5(ppoll, struct pollfd __user *, ufds, unsigned int, nfds, ret = do_sys_poll(ufds, nfds, to); + restore_user_sigmask(sigmask, &sigsaved); + /* We can restart this syscall, usually */ - if (ret == -EINTR) { - /* - * Don't restore the signal mask yet. Let do_signal() deliver - * the signal on the way back to userspace, before the signal - * mask is restored. - */ - if (sigmask) { - memcpy(¤t->saved_sigmask, &sigsaved, - sizeof(sigsaved)); - set_restore_sigmask(); - } + if (ret == -EINTR) ret = -ERESTARTNOHAND; - } else if (sigmask) - sigprocmask(SIG_SETMASK, &sigsaved, NULL); ret = poll_select_copy_remaining(&end_time, tsp, 0, ret); @@ -1316,19 +1294,7 @@ static long do_compat_pselect(int n, compat_ulong_t __user *inp, ret = compat_core_sys_select(n, inp, outp, exp, to); ret = compat_poll_select_copy_remaining(&end_time, tsp, 0, ret); - if (ret == -ERESTARTNOHAND) { - /* - * Don't restore the signal mask yet. Let do_signal() deliver - * the signal on the way back to userspace, before the signal - * mask is restored. - */ - if (sigmask) { - memcpy(¤t->saved_sigmask, &sigsaved, - sizeof(sigsaved)); - set_restore_sigmask(); - } - } else if (sigmask) - sigprocmask(SIG_SETMASK, &sigsaved, NULL); + restore_user_sigmask(sigmask, &sigsaved); return ret; } @@ -1375,21 +1341,11 @@ COMPAT_SYSCALL_DEFINE5(ppoll, struct pollfd __user *, ufds, ret = do_sys_poll(ufds, nfds, to); + restore_user_sigmask(sigmask, &sigsaved); + /* We can restart this syscall, usually */ - if (ret == -EINTR) { - /* - * Don't restore the signal mask yet. Let do_signal() deliver - * the signal on the way back to userspace, before the signal - * mask is restored. - */ - if (sigmask) { - memcpy(¤t->saved_sigmask, &sigsaved, - sizeof(sigsaved)); - set_restore_sigmask(); - } + if (ret == -EINTR) ret = -ERESTARTNOHAND; - } else if (sigmask) - sigprocmask(SIG_SETMASK, &sigsaved, NULL); ret = compat_poll_select_copy_remaining(&end_time, tsp, 0, ret); diff --git a/include/linux/signal.h b/include/linux/signal.h index 403e63d01bcf..ed8be17afe89 100644 --- a/include/linux/signal.h +++ b/include/linux/signal.h @@ -265,6 +265,8 @@ extern int __group_send_sig_info(int, struct siginfo *, struct task_struct *); extern int sigprocmask(int, sigset_t *, sigset_t *); extern int set_user_sigmask(const sigset_t __user *usigmask, sigset_t *set, sigset_t *oldset, size_t sigsetsize); +extern void restore_user_sigmask(const void __user *usigmask, + sigset_t *sigsaved); extern void set_current_blocked(sigset_t *); extern void __set_current_blocked(const sigset_t *); extern int show_unhandled_signals; diff --git a/kernel/signal.c b/kernel/signal.c index 1d72dcddcaaf..457d1abe62a4 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -2783,6 +2783,39 @@ int set_compat_user_sigmask(const compat_sigset_t __user *usigmask, EXPORT_SYMBOL(set_compat_user_sigmask); #endif +/* + * restore_user_sigmask: + * usigmask: sigmask passed in from userland. + * sigsaved: saved sigmask when the syscall started and changed the sigmask to + * usigmask. + * + * This is useful for syscalls such as ppoll, pselect, io_pgetevents and + * epoll_pwait where a new sigmask is passed in from userland for the syscalls. + */ +void restore_user_sigmask(const void __user *usigmask, sigset_t *sigsaved) +{ + + if (!usigmask) + return; + /* + * When signals are pending, do not restore them here. + * Restoring sigmask here can lead to delivering signals that the above + * syscalls are intended to block because of the sigmask passed in. + */ + if (signal_pending(current)) { + current->saved_sigmask = *sigsaved; + set_restore_sigmask(); + return; + } + + /* + * This is needed because the fast syscall return path does not restore + * saved_sigmask when signals are not pending. + */ + set_current_blocked(sigsaved); +} +EXPORT_SYMBOL(restore_user_sigmask); + /** * sys_rt_sigprocmask - change the list of currently blocked signals * @how: whether to add, remove, or set signals