From nobody Sun Sep 14 16:30:06 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 62CABC38A23 for ; Fri, 20 Jan 2023 14:45:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230416AbjATOpd (ORCPT ); Fri, 20 Jan 2023 09:45:33 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50980 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231127AbjATOp1 (ORCPT ); Fri, 20 Jan 2023 09:45:27 -0500 Received: from mail-il1-x141.google.com (mail-il1-x141.google.com [IPv6:2607:f8b0:4864:20::141]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 70976D0DBF; Fri, 20 Jan 2023 06:44:50 -0800 (PST) Received: by mail-il1-x141.google.com with SMTP id r19so2415937ilt.7; Fri, 20 Jan 2023 06:44:50 -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=tm7r7/w+NTSuvZBNcrJh41bBRzvQQKHJ+pSw3+ziM6w=; b=d9hrNAP1hM3jAB/eHeVYlSgAOzwZ6HpHsmGPUB9k/S3hJoKV6ZKXsNpcifJyXeFd1Z hOsIOWnEERynuF11cD7WkoqawYUwuoJ3Oko5+nxiVlTcRTwod/Y08ApHYZdFv/69N3x6 v9MBqMTqSHJ1jRPWVVrgVfaEOoYQgpn8+CiNEXrPULJtiYwH2upRnZlgDQ92UYnRqacO +ArPEu/p4v6CemcpChZMdHYXi3DqWUQuNGIcZPbLWWwrSwplUDoRiKj4j8QQ124qvPLu PvHYP1wruhHnATYaw3JLcYo1hI5MkbSDeSHwBKldHWWmqB6xofNCZYq4ARwcL7lgLRcR bY6w== 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=tm7r7/w+NTSuvZBNcrJh41bBRzvQQKHJ+pSw3+ziM6w=; b=I4g8cT52z8iYarGDPCf2cZmXvKee43p8UWz7fVYW5+VHE5krzr3NlY/ITmtOdQfl9i kaIho/EXJHU66L6zuluzuDE1S0iu0kP9C0Q1/X9xd9iJJj6+387C1LcszMz/S2foANcg MzAmJybWTLzTDiqLIo6xjDevy86+ABhUDpMAJ1vyAERX8a2RTs0AMB2cqLcvbrbZhU3p 09iwsttRh8IR55Qr0Bl0Q92CifLLI9kvIej+7ttS0+QZpDpzfUqWbnF+15QcBoTwtN18 xsnQn6Ee+7dXKvFdM8x8x8dZo4CoalRa8jfYbLOENinM0WUPOquMDUEhziL1C6PDKSWa boxg== X-Gm-Message-State: AFqh2krutihkb46gButhchxjbK4IuRfLEDI4geddNpdLehRh/ac4A7VA LFYpmDORM7FQkbccN3fvG3BU/hzN89RA X-Google-Smtp-Source: AMrXdXvFwKixDS/TIXDil0+nxTTZXuD9Hv1Pb5U4CyB5pJAmfEvnE626Cy7OLk1Q8SFJUdjAiwK6TA== X-Received: by 2002:a92:2e09:0:b0:30f:1a48:b5ac with SMTP id v9-20020a922e09000000b0030f1a48b5acmr9475876ile.20.1674225859097; Fri, 20 Jan 2023 06:44:19 -0800 (PST) Received: from fedora.mshome.net ([104.184.156.161]) by smtp.gmail.com with ESMTPSA id p185-20020a0229c2000000b003a7c47efde0sm1513852jap.11.2023.01.20.06.44.16 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 20 Jan 2023 06:44:18 -0800 (PST) From: Gregory Price X-Google-Original-From: Gregory Price To: linux-kernel@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, krisman@collabora.com, tglx@linutronix.de, luto@kernel.org, oleg@redhat.com, peterz@infradead.org, ebiederm@xmission.com, akpm@linux-foundation.org, adobriyan@gmail.com, corbet@lwn.net, shuah@kernel.org, Gregory Price Subject: [PATCH v3 3/3] ptrace,syscall_user_dispatch: add a getter/setter for sud configuration Date: Fri, 20 Jan 2023 09:43:56 -0500 Message-Id: <20230120144356.40717-4-gregory.price@memverge.com> X-Mailer: git-send-email 2.39.0 In-Reply-To: <20230120144356.40717-1-gregory.price@memverge.com> References: <20230120144356.40717-1-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. Presently, these settings are write-only via prctl, making it impossible to implement transparent checkpoint (coordination with the software is required). This is modeled after a similar interface for SECCOMP, which can have its configuration dumped by ptrace for software like CRIU. Signed-off-by: Gregory Price --- .../admin-guide/syscall-user-dispatch.rst | 5 +- include/linux/syscall_user_dispatch.h | 19 +++++++ include/uapi/linux/ptrace.h | 10 ++++ kernel/entry/syscall_user_dispatch.c | 49 +++++++++++++++++++ kernel/ptrace.c | 9 ++++ 5 files changed, 91 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..8b93c78189b5 100644 --- a/include/uapi/linux/ptrace.h +++ b/include/uapi/linux/ptrace.h @@ -112,6 +112,16 @@ 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; + __u8 on_dispatch; +}; + /* * 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..a3b24d498b39 100644 --- a/kernel/entry/syscall_user_dispatch.c +++ b/kernel/entry/syscall_user_dispatch.c @@ -111,3 +111,52 @@ 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 (sd->selector) { + config.mode =3D PR_SYS_DISPATCH_ON; + config.offset =3D sd->offset; + config.len =3D sd->len; + config.selector =3D sd->selector; + config.on_dispatch =3D sd->on_dispatch; + } else { + config.mode =3D PR_SYS_DISPATCH_OFF; + config.offset =3D 0; + config.len =3D 0; + config.selector =3D NULL; + config.on_dispatch =3D false; + } + 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; + + ret =3D set_syscall_user_dispatch(config.mode, config.offset, config.len, + config.selector); + if (ret) + return ret; + + task->syscall_dispatch.on_dispatch =3D config.on_dispatch; + return 0; +} diff --git a/kernel/ptrace.c b/kernel/ptrace.c index 99467ba5f55b..d1e9c0808905 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