From patchwork Mon Apr 13 16:51:42 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Arnaldo Carvalho de Melo X-Patchwork-Id: 11486017 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 2C09314B4 for ; Mon, 13 Apr 2020 16:55:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0CCC820780 for ; Mon, 13 Apr 2020 16:55:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1586796907; bh=bsha3xY0b0htxjAC74+rhyzPRn3pa6BRck29iTQylnQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=F/HbaQ1r502gs4Bn3FmgaSmGzMhxHTOUlX0fhVQeVkYdPRfPvUgW1Y5CY1jBlpbHh e3QDqcecmTeX9wu46vUPmKNeW3BBL/cIo3DYsmlQuQj6DUiybERb1eH5IvukqcSCyX xThyWqb+Udtg5Np4J27fpHU/e84k+ftN0vvZDUro= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731878AbgDMQwj (ORCPT ); Mon, 13 Apr 2020 12:52:39 -0400 Received: from mail.kernel.org ([198.145.29.99]:44160 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731870AbgDMQwh (ORCPT ); Mon, 13 Apr 2020 12:52:37 -0400 Received: from quaco.ghostprotocols.net (unknown [179.97.37.151]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id BDACE20857; Mon, 13 Apr 2020 16:52:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1586796756; bh=bsha3xY0b0htxjAC74+rhyzPRn3pa6BRck29iTQylnQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=vOyCN8Q/sTPseoZteALKxvDyyep46Pk//XGWf/kI2kc1EPeNnPoD4sOZfyN4nQwX1 hiZGsr9uPWoQ78JTlSCk/cJQxMKOJd1zwIEpqQ/A1Ez6Z+Y8kkcSIIyCuFOaxF7ekd 8hOgvv4ax+kGpDQmcHQE+8VVh6cuU6QrVP87kDNk= From: Arnaldo Carvalho de Melo To: Ingo Molnar , Thomas Gleixner Cc: Jiri Olsa , Namhyung Kim , Clark Williams , linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, Alexey Budankov , James Morris , "Serge E . Hallyn" , Song Liu , Stephen Smalley , Arnaldo Carvalho de Melo , Alexei Starovoitov , Andi Kleen , Igor Lubashev , Jiri Olsa , Peter Zijlstra , Stephane Eranian , intel-gfx@lists.freedesktop.org, linux-doc@vger.kernel.org, linux-man@vger.kernel.org, linux-security-module@vger.kernel.org, selinux@vger.kernel.org Subject: [PATCH 05/26] capabilities: Introduce CAP_PERFMON to kernel and user space Date: Mon, 13 Apr 2020 13:51:42 -0300 Message-Id: <20200413165203.1816-6-acme@kernel.org> X-Mailer: git-send-email 2.21.1 In-Reply-To: <20200413165203.1816-1-acme@kernel.org> References: <20200413165203.1816-1-acme@kernel.org> MIME-Version: 1.0 Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: From: Alexey Budankov Introduce the CAP_PERFMON capability designed to secure system performance monitoring and observability operations so that CAP_PERFMON can assist CAP_SYS_ADMIN capability in its governing role for performance monitoring and observability subsystems. CAP_PERFMON hardens system security and integrity during performance monitoring and observability operations by decreasing attack surface that is available to a CAP_SYS_ADMIN privileged process [2]. Providing the access to system performance monitoring and observability operations under CAP_PERFMON capability singly, without the rest of CAP_SYS_ADMIN credentials, excludes chances to misuse the credentials and makes the operation more secure. Thus, CAP_PERFMON implements the principle of least privilege for performance monitoring and observability operations (POSIX IEEE 1003.1e: 2.2.2.39 principle of least privilege: A security design principle that states that a process or program be granted only those privileges (e.g., capabilities) necessary to accomplish its legitimate function, and only for the time that such privileges are actually required) CAP_PERFMON meets the demand to secure system performance monitoring and observability operations for adoption in security sensitive, restricted, multiuser production environments (e.g. HPC clusters, cloud and virtual compute environments), where root or CAP_SYS_ADMIN credentials are not available to mass users of a system, and securely unblocks applicability and scalability of system performance monitoring and observability operations beyond root and CAP_SYS_ADMIN use cases. CAP_PERFMON takes over CAP_SYS_ADMIN credentials related to system performance monitoring and observability operations and balances amount of CAP_SYS_ADMIN credentials following the recommendations in the capabilities man page [1] for CAP_SYS_ADMIN: "Note: this capability is overloaded; see Notes to kernel developers, below." For backward compatibility reasons access to system performance monitoring and observability subsystems of the kernel remains open for CAP_SYS_ADMIN privileged processes but CAP_SYS_ADMIN capability usage for secure system performance monitoring and observability operations is discouraged with respect to the designed CAP_PERFMON capability. Although the software running under CAP_PERFMON can not ensure avoidance of related hardware issues, the software can still mitigate these issues following the official hardware issues mitigation procedure [2]. The bugs in the software itself can be fixed following the standard kernel development process [3] to maintain and harden security of system performance monitoring and observability operations. [1] http://man7.org/linux/man-pages/man7/capabilities.7.html [2] https://www.kernel.org/doc/html/latest/process/embargoed-hardware-issues.html [3] https://www.kernel.org/doc/html/latest/admin-guide/security-bugs.html Signed-off-by: Alexey Budankov Acked-by: James Morris Acked-by: Serge E. Hallyn Acked-by: Song Liu Acked-by: Stephen Smalley Tested-by: Arnaldo Carvalho de Melo Cc: Alexei Starovoitov Cc: Andi Kleen Cc: Igor Lubashev Cc: Jiri Olsa Cc: Namhyung Kim Cc: Peter Zijlstra Cc: Stephane Eranian Cc: Thomas Gleixner Cc: intel-gfx@lists.freedesktop.org Cc: linux-doc@vger.kernel.org Cc: linux-man@vger.kernel.org Cc: linux-security-module@vger.kernel.org Cc: selinux@vger.kernel.org Link: http://lore.kernel.org/lkml/5590d543-82c6-490a-6544-08e6a5517db0@linux.intel.com Signed-off-by: Arnaldo Carvalho de Melo --- include/linux/capability.h | 4 ++++ include/uapi/linux/capability.h | 8 +++++++- security/selinux/include/classmap.h | 4 ++-- 3 files changed, 13 insertions(+), 3 deletions(-) diff --git a/include/linux/capability.h b/include/linux/capability.h index ecce0f43c73a..027d7e4a853b 100644 --- a/include/linux/capability.h +++ b/include/linux/capability.h @@ -251,6 +251,10 @@ extern bool privileged_wrt_inode_uidgid(struct user_namespace *ns, const struct extern bool capable_wrt_inode_uidgid(const struct inode *inode, int cap); extern bool file_ns_capable(const struct file *file, struct user_namespace *ns, int cap); extern bool ptracer_capable(struct task_struct *tsk, struct user_namespace *ns); +static inline bool perfmon_capable(void) +{ + return capable(CAP_PERFMON) || capable(CAP_SYS_ADMIN); +} /* audit system wants to get cap info from files as well */ extern int get_vfs_caps_from_disk(const struct dentry *dentry, struct cpu_vfs_cap_data *cpu_caps); diff --git a/include/uapi/linux/capability.h b/include/uapi/linux/capability.h index 272dc69fa080..e58c9636741b 100644 --- a/include/uapi/linux/capability.h +++ b/include/uapi/linux/capability.h @@ -367,8 +367,14 @@ struct vfs_ns_cap_data { #define CAP_AUDIT_READ 37 +/* + * Allow system performance and observability privileged operations + * using perf_events, i915_perf and other kernel subsystems + */ + +#define CAP_PERFMON 38 -#define CAP_LAST_CAP CAP_AUDIT_READ +#define CAP_LAST_CAP CAP_PERFMON #define cap_valid(x) ((x) >= 0 && (x) <= CAP_LAST_CAP) diff --git a/security/selinux/include/classmap.h b/security/selinux/include/classmap.h index 986f3ac14282..d233ab3f1533 100644 --- a/security/selinux/include/classmap.h +++ b/security/selinux/include/classmap.h @@ -27,9 +27,9 @@ "audit_control", "setfcap" #define COMMON_CAP2_PERMS "mac_override", "mac_admin", "syslog", \ - "wake_alarm", "block_suspend", "audit_read" + "wake_alarm", "block_suspend", "audit_read", "perfmon" -#if CAP_LAST_CAP > CAP_AUDIT_READ +#if CAP_LAST_CAP > CAP_PERFMON #error New capability defined, please update COMMON_CAP2_PERMS. #endif