From nobody Sun Sep 14 09:33:11 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E7188C38142 for ; Wed, 25 Jan 2023 02:51:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234059AbjAYCvj (ORCPT ); Tue, 24 Jan 2023 21:51:39 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33948 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233858AbjAYCvh (ORCPT ); Tue, 24 Jan 2023 21:51:37 -0500 Received: from mail-il1-x142.google.com (mail-il1-x142.google.com [IPv6:2607:f8b0:4864:20::142]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C264030288; Tue, 24 Jan 2023 18:51:36 -0800 (PST) Received: by mail-il1-x142.google.com with SMTP id p12so8287174ilq.10; Tue, 24 Jan 2023 18:51:36 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=24Kolj4JV2M8McXm4v+n0gLJPa8chzLkxYYS/Gp9uYA=; b=qiUQa29oCQ/fE3FNK/vPFR4Z9FNDSdmIwperpGyCa38eq/VZa0Rr2IVYj57pZu4EVN lsN9agJDKwhyZV597ptufaH5qNhPlXhqF4jOnU6VC6kwq+9O1S56QZ+fYU4Dsc59YzKg 3iKJxDWS0pRvU0uEHnsYIEmmnVjAHJ0uSRLTsSCgZ7ZZP3EkQfS05a1wPn+s05/MCRYM gMoR03qYJcUZ1mhC8Pvgd28CyBfHdy9hgU34MUFiK5OdcdTZ3TUvlzWv7IKUrkWGe50f edh0ANw9sZB9KB+TvgXw1/2xrAm90umcF8ir/H50A9a2z/xzMJHBhJI1fmDookyNUtlG 6eHw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=24Kolj4JV2M8McXm4v+n0gLJPa8chzLkxYYS/Gp9uYA=; b=GPcNilnM026IkZJAWVZxreDB5fpTfk4DsbHQ3w3U6AikpaiesiwSK0GsXyWN4BzCXV GrBsNWUdyqZdFG65yOYez1korbusHXdp/FLt3gW25nH0Wr2sXZIHqrX5TlW4YRMIMZNf a6ZC0omVctMQsSr8nDMkpsHuU9+C+cewTrSVXICvlOcoa0v2+y0UeZT4Jafv+4uvL5aZ oioLXsl+qPGWcKZ7OK0UHc3ZX7q3XD561bXIg5h7HrfQdJOfoHGbrrNEIVEejC8EBAXN x3Fc/1fTeRVC3Er7CkVx18yvPK0NXKNZdb3DQOSH2h34I2aVO7owOrwMGXL4WuZCWuPa 4k8g== X-Gm-Message-State: AFqh2kqtExfvrmrsmEVf6yLHU7tqZ9wXSh0ktaFa+eJGgCEBs667OTcp kZCvOVBqfCL047YLsm7HPDAkUcljFgli X-Google-Smtp-Source: AMrXdXvp3tVSPZgAOl73+DM9I8Te+hxp1Ua7hWEL/hSVSDluM2WJaMz5V1od/doJf+p0gHrDnI8qug== X-Received: by 2002:a05:6e02:1562:b0:30f:3736:25ab with SMTP id k2-20020a056e02156200b0030f373625abmr20523982ilu.28.1674615096348; Tue, 24 Jan 2023 18:51:36 -0800 (PST) Received: from fedora.mshome.net ([104.184.156.161]) by smtp.gmail.com with ESMTPSA id v5-20020a023845000000b0038a13e116a1sm1265722jae.61.2023.01.24.18.51.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 24 Jan 2023 18:51:35 -0800 (PST) From: Gregory Price X-Google-Original-From: Gregory Price To: linux-kernel@vger.kernel.org Cc: linux-doc@vger.kernel.org, oleg@redhat.com, avagin@gmail.com, peterz@infradead.org, luto@kernel.org, krisman@collabora.com, tglx@linutronix.de, corbet@lwn.net, shuah@kernel.org, Gregory Price Subject: [PATCH v6 1/2] ptrace,syscall_user_dispatch: Implement Syscall User Dispatch Suspension Date: Tue, 24 Jan 2023 21:51:25 -0500 Message-Id: <20230125025126.787431-2-gregory.price@memverge.com> X-Mailer: git-send-email 2.39.0 In-Reply-To: <20230125025126.787431-1-gregory.price@memverge.com> References: <20230125025126.787431-1-gregory.price@memverge.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Adds PTRACE_O_SUSPEND_SYSCALL_USER_DISPATCH to ptrace options, and modify Syscall User Dispatch to suspend interception when enabled. This is modeled after the SUSPEND_SECCOMP feature, which suspends SECCOMP interposition. Without doing this, software like CRIU will inject system calls into a process and be intercepted by Syscall User Dispatch, either causing a crash (due to blocked signals) or the delivery of those signals to a ptracer (not the intended behavior). Since Syscall User Dispatch is not a privileged feature, a check for permissions is not required, however attempting to set this option when CONFIG_CHECKPOINT_RESTORE it not supported should be disallowed, as its intended use is checkpoint/resume. Signed-off-by: Gregory Price Acked-by: Peter Zijlstra (Intel) Reviewed-by: Oleg Nesterov --- include/linux/ptrace.h | 2 ++ include/uapi/linux/ptrace.h | 6 +++++- kernel/entry/syscall_user_dispatch.c | 5 +++++ kernel/ptrace.c | 4 ++++ 4 files changed, 16 insertions(+), 1 deletion(-) diff --git a/include/linux/ptrace.h b/include/linux/ptrace.h index eaaef3ffec22..461ae5c99d57 100644 --- a/include/linux/ptrace.h +++ b/include/linux/ptrace.h @@ -45,6 +45,8 @@ extern int ptrace_access_vm(struct task_struct *tsk, unsi= gned long addr, =20 #define PT_EXITKILL (PTRACE_O_EXITKILL << PT_OPT_FLAG_SHIFT) #define PT_SUSPEND_SECCOMP (PTRACE_O_SUSPEND_SECCOMP << PT_OPT_FLAG_SHIFT) +#define PT_SUSPEND_SYSCALL_USER_DISPATCH \ + (PTRACE_O_SUSPEND_SYSCALL_USER_DISPATCH << PT_OPT_FLAG_SHIFT) =20 extern long arch_ptrace(struct task_struct *child, long request, unsigned long addr, unsigned long data); diff --git a/include/uapi/linux/ptrace.h b/include/uapi/linux/ptrace.h index 195ae64a8c87..ba9e3f19a22c 100644 --- a/include/uapi/linux/ptrace.h +++ b/include/uapi/linux/ptrace.h @@ -146,9 +146,13 @@ struct ptrace_rseq_configuration { /* eventless options */ #define PTRACE_O_EXITKILL (1 << 20) #define PTRACE_O_SUSPEND_SECCOMP (1 << 21) +#define PTRACE_O_SUSPEND_SYSCALL_USER_DISPATCH (1 << 22) =20 #define PTRACE_O_MASK (\ - 0x000000ff | PTRACE_O_EXITKILL | PTRACE_O_SUSPEND_SECCOMP) + 0x000000ff | \ + PTRACE_O_EXITKILL | \ + PTRACE_O_SUSPEND_SECCOMP | \ + PTRACE_O_SUSPEND_SYSCALL_USER_DISPATCH) =20 #include =20 diff --git a/kernel/entry/syscall_user_dispatch.c b/kernel/entry/syscall_us= er_dispatch.c index 0b6379adff6b..b5ec75164805 100644 --- a/kernel/entry/syscall_user_dispatch.c +++ b/kernel/entry/syscall_user_dispatch.c @@ -8,6 +8,7 @@ #include #include #include +#include =20 #include #include @@ -36,6 +37,10 @@ bool syscall_user_dispatch(struct pt_regs *regs) struct syscall_user_dispatch *sd =3D ¤t->syscall_dispatch; char state; =20 + if (IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) && + unlikely(current->ptrace & PT_SUSPEND_SYSCALL_USER_DISPATCH)) + return false; + if (likely(instruction_pointer(regs) - sd->offset < sd->len)) return false; =20 diff --git a/kernel/ptrace.c b/kernel/ptrace.c index 54482193e1ed..a348b68d07a2 100644 --- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -370,6 +370,10 @@ static int check_ptrace_options(unsigned long data) if (data & ~(unsigned long)PTRACE_O_MASK) return -EINVAL; =20 + if (unlikely(data & PTRACE_O_SUSPEND_SYSCALL_USER_DISPATCH) && + (!IS_ENABLED(CONFIG_CHECKPOINT_RESTORE))) + return -EINVAL; + if (unlikely(data & PTRACE_O_SUSPEND_SECCOMP)) { if (!IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) || !IS_ENABLED(CONFIG_SECCOMP)) --=20 2.39.0