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 06F4EC38142 for ; Wed, 25 Jan 2023 02:51:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233858AbjAYCvs (ORCPT ); Tue, 24 Jan 2023 21:51:48 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34232 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234107AbjAYCvp (ORCPT ); Tue, 24 Jan 2023 21:51:45 -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 9078E539BD; Tue, 24 Jan 2023 18:51:41 -0800 (PST) Received: by mail-il1-x142.google.com with SMTP id i17so8284242ila.9; Tue, 24 Jan 2023 18:51:41 -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=HVOnr9X3NZfRTxwQMKhCnEXQXYREpSkn5siHkgp3Q+8=; b=O139B5k8qR284vjoPwjnF+U5bBM3w6GG+l7LlqDrBkJsrCn5xxs8rjRcIQHWF4NUP8 KJTz1Lv8kzENCOYOJLkqlwRvp2zLocpiCQKn9X5UxuwgdQS2kpYcaqNnCIfyBUiUjitY ugtGIIw06VPAj4o0kkOcJFQy3Ih6WiMqsl7rrTcHY6ItPPJMJDEfwk/O6ShvxKJcslpW Y9/Ia9t3wIMCR5Ip6AKf2MVQsjxUzzpaRcNhZ3mh6AK2Mb8NY3259PfSg4Bin/dotOZV VZMcMp+Qa62bD4aZZhGfCbnU94mfMrlYVkyfFYOyIEH5PVqtMXe2ISZ7jjD7XQTvts51 Fakw== 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=HVOnr9X3NZfRTxwQMKhCnEXQXYREpSkn5siHkgp3Q+8=; b=F4FY+BXqcv+/ZuT7ygaS+CtQdVXUjUKLMTwrrXYEamk1xTfU659Ahj49imueZ32qiM 9dfnSBp26CXF908VhGu5D2V9DNBHTBe3O0kq1+0V3OSaeOjhv97wa1SMAQx5QoRSV4nd 1xClwZI00qF6457irfFGbEaVSBAtT/L0CTvwJ+ePj6tEevPOh2QKDMVlhJTD9tUlrQ4H vhYGDATsbXk0qEGPMW8z0Yf44MTREELLGfiB7u4OHdKDqsdQEkjI6ey6LWn64UEBYa3n tB9W1pinVBSPdide8LjJRuLujxffrTbOSP2lpKZx10OheRJDd5SJprEs9vKOSq2+BXnY 0ngg== X-Gm-Message-State: AO0yUKWjVe5NfC7lrtael/2JGb3VFYuepXUqLnc5XAH0l7ozgzE1s7JX OL2KogcBDoRgNFQG9iwyX2DH7pswvmix X-Google-Smtp-Source: AK7set9eyd4ZgOq0rRch2zEwPO05tvZoZD+qfbBf/C5js+MubnuOM8i+lJ5RLQH1ZbCuJgNUt0QriQ== X-Received: by 2002:a05:6e02:20c3:b0:310:a12c:78a2 with SMTP id 3-20020a056e0220c300b00310a12c78a2mr872263ilq.6.1674615100667; Tue, 24 Jan 2023 18:51:40 -0800 (PST) Received: from fedora.mshome.net ([104.184.156.161]) by smtp.gmail.com with ESMTPSA id v5-20020a023845000000b0038a13e116a1sm1265722jae.61.2023.01.24.18.51.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 24 Jan 2023 18:51:40 -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 2/2] ptrace,syscall_user_dispatch: add a getter/setter for sud configuration Date: Tue, 24 Jan 2023 21:51:26 -0500 Message-Id: <20230125025126.787431-3-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" Implement ptrace getter/setter interface for syscall user dispatch. These prctl settings are presently write-only, making it impossible to implement transparent checkpoint via software like CRIU. This is modeled after a similar interface for SECCOMP, which can have its configuration dumped by ptrace. Signed-off-by: Gregory Price --- .../admin-guide/syscall-user-dispatch.rst | 5 ++- include/linux/syscall_user_dispatch.h | 19 +++++++++ include/uapi/linux/ptrace.h | 9 +++++ kernel/entry/syscall_user_dispatch.c | 40 +++++++++++++++++++ kernel/ptrace.c | 9 +++++ 5 files changed, 81 insertions(+), 1 deletion(-) diff --git a/Documentation/admin-guide/syscall-user-dispatch.rst b/Document= ation/admin-guide/syscall-user-dispatch.rst index 60314953c728..a23ae21a1d5b 100644 --- a/Documentation/admin-guide/syscall-user-dispatch.rst +++ b/Documentation/admin-guide/syscall-user-dispatch.rst @@ -43,7 +43,10 @@ doesn't rely on any of the syscall ABI to make the filte= ring. It uses only the syscall dispatcher address and the userspace key. =20 As the ABI of these intercepted syscalls is unknown to Linux, these -syscalls are not instrumentable via ptrace or the syscall tracepoints. +syscalls are not instrumentable via ptrace or the syscall tracepoints, +however an interfaces to suspend, checkpoint, and restore syscall user +dispatch configuration has been added to ptrace to assist userland +checkpoint/restart software. =20 Interface --------- diff --git a/include/linux/syscall_user_dispatch.h b/include/linux/syscall_= user_dispatch.h index a0ae443fb7df..9e1bd0d87c1e 100644 --- a/include/linux/syscall_user_dispatch.h +++ b/include/linux/syscall_user_dispatch.h @@ -22,6 +22,13 @@ int set_syscall_user_dispatch(unsigned long mode, unsign= ed long offset, #define clear_syscall_work_syscall_user_dispatch(tsk) \ clear_task_syscall_work(tsk, SYSCALL_USER_DISPATCH) =20 +int syscall_user_dispatch_get_config(struct task_struct *task, unsigned lo= ng size, + void __user *data); + +int syscall_user_dispatch_set_config(struct task_struct *task, unsigned lo= ng size, + void __user *data); + + #else struct syscall_user_dispatch {}; =20 @@ -35,6 +42,18 @@ static inline void clear_syscall_work_syscall_user_dispa= tch(struct task_struct * { } =20 +static inline int syscall_user_dispatch_get_config(struct task_struct *tas= k, unsigned long size, + void __user *data) +{ + return -EINVAL; +} + +static inline int syscall_user_dispatch_set_config(struct task_struct *tas= k, unsigned long size, + void __user *data) +{ + return -EINVAL; +} + #endif /* CONFIG_GENERIC_ENTRY */ =20 #endif /* _SYSCALL_USER_DISPATCH_H */ diff --git a/include/uapi/linux/ptrace.h b/include/uapi/linux/ptrace.h index ba9e3f19a22c..53ef59134dcb 100644 --- a/include/uapi/linux/ptrace.h +++ b/include/uapi/linux/ptrace.h @@ -112,6 +112,15 @@ struct ptrace_rseq_configuration { __u32 pad; }; =20 +#define PTRACE_SET_SYSCALL_USER_DISPATCH_CONFIG 0x4210 +#define PTRACE_GET_SYSCALL_USER_DISPATCH_CONFIG 0x4211 +struct syscall_user_dispatch_config { + __u64 mode; + __s8 *selector; + __u64 offset; + __u64 len; +}; + /* * These values are stored in task->ptrace_message * by ptrace_stop to describe the current syscall-stop. diff --git a/kernel/entry/syscall_user_dispatch.c b/kernel/entry/syscall_us= er_dispatch.c index b5ec75164805..ee02ce21f75e 100644 --- a/kernel/entry/syscall_user_dispatch.c +++ b/kernel/entry/syscall_user_dispatch.c @@ -111,3 +111,43 @@ int set_syscall_user_dispatch(unsigned long mode, unsi= gned long offset, =20 return 0; } + +int syscall_user_dispatch_get_config(struct task_struct *task, unsigned lo= ng size, + void __user *data) +{ + struct syscall_user_dispatch *sd =3D &task->syscall_dispatch; + struct syscall_user_dispatch_config config; + + if (size !=3D sizeof(struct syscall_user_dispatch_config)) + return -EINVAL; + + if (test_syscall_work(SYSCALL_USER_DISPATCH)) + config.mode =3D PR_SYS_DISPATCH_ON; + else + config.mode =3D PR_SYS_DISPATCH_OFF; + + config.offset =3D sd->offset; + config.len =3D sd->len; + config.selector =3D sd->selector; + + if (copy_to_user(data, &config, sizeof(config))) + return -EFAULT; + + return 0; +} + +int syscall_user_dispatch_set_config(struct task_struct *task, unsigned lo= ng size, + void __user *data) +{ + struct syscall_user_dispatch_config config; + int ret; + + if (size !=3D sizeof(struct syscall_user_dispatch_config)) + return -EINVAL; + + if (copy_from_user(&config, data, sizeof(config))) + return -EFAULT; + + return set_syscall_user_dispatch(config.mode, config.offset, config.len, + config.selector); +} diff --git a/kernel/ptrace.c b/kernel/ptrace.c index a348b68d07a2..76de46e080e2 100644 --- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -32,6 +32,7 @@ #include #include #include +#include =20 #include /* for syscall_get_* */ =20 @@ -1263,6 +1264,14 @@ int ptrace_request(struct task_struct *child, long r= equest, break; #endif =20 + case PTRACE_SET_SYSCALL_USER_DISPATCH_CONFIG: + ret =3D syscall_user_dispatch_set_config(child, addr, datavp); + break; + + case PTRACE_GET_SYSCALL_USER_DISPATCH_CONFIG: + ret =3D syscall_user_dispatch_get_config(child, addr, datavp); + break; + default: break; } --=20 2.39.0