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[173.79.56.208]) by smtp.gmail.com with ESMTPSA id u3-20020ae9c003000000b0070928ee3933sm4875492qkk.75.2023.01.22.19.29.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 22 Jan 2023 19:29:46 -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 v5 1/3] ptrace,syscall_user_dispatch: Implement Syscall User Dispatch Suspension Date: Sun, 22 Jan 2023 22:29:40 -0500 Message-Id: <20230123032942.18263-2-gregory.price@memverge.com> X-Mailer: git-send-email 2.39.0 In-Reply-To: <20230123032942.18263-1-gregory.price@memverge.com> References: <20230123032942.18263-1-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) --- 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 From nobody Sun Sep 14 11:14:41 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 E568AC25B50 for ; 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[173.79.56.208]) by smtp.gmail.com with ESMTPSA id u3-20020ae9c003000000b0070928ee3933sm4875492qkk.75.2023.01.22.19.29.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 22 Jan 2023 19:29:47 -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 2/3] fs/proc/array: Add Syscall User Dispatch to proc status Date: Sun, 22 Jan 2023 22:29:41 -0500 Message-Id: <20230123032942.18263-3-gregory.price@memverge.com> X-Mailer: git-send-email 2.39.0 In-Reply-To: <20230123032942.18263-1-gregory.price@memverge.com> References: <20230123032942.18263-1-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" Report the value of test_syscall_work(SYSCALL_USER_DISPATCH)) in proc/status if GENERIC_ENTRY is enabled or the arch has implemented it. This provides an indicator to userland checkpoint/restore software that it must manage special signal conditions (similar to SECCOMP) Signed-off-by: Gregory Price --- fs/proc/array.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/fs/proc/array.c b/fs/proc/array.c index 49283b8103c7..d4e4ee2409c6 100644 --- a/fs/proc/array.c +++ b/fs/proc/array.c @@ -428,6 +428,15 @@ static inline void task_thp_status(struct seq_file *m,= struct mm_struct *mm) seq_printf(m, "THP_enabled:\t%d\n", thp_enabled); } =20 +static inline void task_syscall_user_dispatch(struct seq_file *m, + struct task_struct *p) +{ +#if defined(CONFIG_GENERIC_ENTRY) || defined(TIF_SYSCALL_USER_DISPATCH) + seq_put_decimal_ull(m, "\nSyscall_user_dispatch:\t", + test_task_syscall_work(p, SYSCALL_USER_DISPATCH)); +#endif +} + int proc_pid_status(struct seq_file *m, struct pid_namespace *ns, struct pid *pid, struct task_struct *task) { @@ -451,6 +460,7 @@ int proc_pid_status(struct seq_file *m, struct pid_name= space *ns, task_cpus_allowed(m, task); cpuset_task_status_allowed(m, task); task_context_switch_counts(m, task); + task_syscall_user_dispatch(m, task); return 0; } =20 --=20 2.39.0 From nobody Sun Sep 14 11:14:41 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 01325C05027 for ; Mon, 23 Jan 2023 03:30:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231475AbjAWD34 (ORCPT ); Sun, 22 Jan 2023 22:29:56 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34332 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230369AbjAWD3v (ORCPT ); Sun, 22 Jan 2023 22:29:51 -0500 Received: from mail-qt1-x844.google.com (mail-qt1-x844.google.com [IPv6:2607:f8b0:4864:20::844]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DBD691448C; Sun, 22 Jan 2023 19:29:49 -0800 (PST) Received: by mail-qt1-x844.google.com with SMTP id q15so8855101qtn.0; Sun, 22 Jan 2023 19:29:49 -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=RgFqur+BidWWWQr7r2LPXldx8oTQot1Qp1tXD/WiXfY=; b=aXerHjM3OC9ndo5Q3C5+pmGodhG7mKJqaptfNyYdWWWNcNr4xq/0TBLKrBw5ESXsgZ jg84s/XqTxsrimKQi0dUWE78pQbysFgKHvIkoQkwwff/xN76aFA2SM7zUsEt97NLRGvf hhnz3cghJZJQvr+AksoDwjCC2lOLQLSSGAf/7uRXI4l2WUslQtp5QsTVBvvV52iug8TU ryvrH8sHHbxl0zCVCIqaouo/8L35n4O/DeTswGU1OwQInxypnrt1x4or34qZioeLfc3i NJXBo2Oux6Mz2B1Ccn1Qw642J2aj/HxdBjwc0Hau6IAKbl7BM31NqCs8yztb65Nkpok6 jQVw== 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=RgFqur+BidWWWQr7r2LPXldx8oTQot1Qp1tXD/WiXfY=; b=1N1AmouTS2P/Ul2ZF52QjOZRqXnCa1rpvbc7zinl5djgdnEXIGOjFk/zD5z//G+jJd KjhpF5Absle7w5IroNsCqkUdbdYwxf0v3m9ZN6y2s8WzPBjpNXYsy0tYye2PQGLfdj4D 1xi13/UHArm28QASeC1U2mLlkBwZBNUSm6AuQOF2Vmk5rUtwkRcbR0Fid+eI7LEj2nGU K6LH4sAti6x5A+D27YkBdmMglkjAxmbkkUQi2rCxGXsDUjmxL5It04OlN8lb82+OHFvI 49r+XLeVgFuJEd2+YzsuriM9QPuQKwGI+FMOoxVY3ZJV0e8Cwvs1xCg8yxrAQDJSxSAd zEOQ== X-Gm-Message-State: AFqh2krUsPNcHkEYj+oTer4u7yUxirbfsTI9paN74JUaat8FucR/Uj/b WYGfprHtk+P0fgSaLa2D0QvMzlP5eM1I X-Google-Smtp-Source: AMrXdXsv+aWdy/Yy/TfkjcpMJTXw3AoOi9BYBga3ld1DyGO8OiG2pQKxViozE8ZYQgu/PcnPGfj7lQ== X-Received: by 2002:ac8:668d:0:b0:3b6:32ef:2dda with SMTP id d13-20020ac8668d000000b003b632ef2ddamr31948335qtp.34.1674444588905; Sun, 22 Jan 2023 19:29:48 -0800 (PST) Received: from fedora.mshome.net (pool-173-79-56-208.washdc.fios.verizon.net. [173.79.56.208]) by smtp.gmail.com with ESMTPSA id u3-20020ae9c003000000b0070928ee3933sm4875492qkk.75.2023.01.22.19.29.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 22 Jan 2023 19:29:48 -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 3/3] ptrace,syscall_user_dispatch: add a getter/setter for sud configuration Date: Sun, 22 Jan 2023 22:29:42 -0500 Message-Id: <20230123032942.18263-4-gregory.price@memverge.com> X-Mailer: git-send-email 2.39.0 In-Reply-To: <20230123032942.18263-1-gregory.price@memverge.com> References: <20230123032942.18263-1-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 | 46 +++++++++++++++++++ kernel/ptrace.c | 9 ++++ 5 files changed, 88 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..a303c8de59af 100644 --- a/kernel/entry/syscall_user_dispatch.c +++ b/kernel/entry/syscall_user_dispatch.c @@ -111,3 +111,49 @@ 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; + config.on_dispatch =3D sd->on_dispatch; + + 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 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