From patchwork Wed Apr 1 21:39:02 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Daniel Colascione X-Patchwork-Id: 11469601 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 E63E4912 for ; Wed, 1 Apr 2020 21:39:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C414F206E9 for ; Wed, 1 Apr 2020 21:39:36 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="hotdlW0v" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1733276AbgDAVjf (ORCPT ); Wed, 1 Apr 2020 17:39:35 -0400 Received: from mail-pf1-f201.google.com ([209.85.210.201]:54252 "EHLO mail-pf1-f201.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1733145AbgDAVjS (ORCPT ); Wed, 1 Apr 2020 17:39:18 -0400 Received: by mail-pf1-f201.google.com with SMTP id i26so879105pfk.20 for ; Wed, 01 Apr 2020 14:39:18 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=6jHUkktZYnLJuOeQ47HqdKglnmNwVQppeyvzohEh60E=; b=hotdlW0vSo7Oc3YxuZoamTSPRrrrCvU+Z/v14Y5TkSuQsHiFXXabwUoA4+ordhQ+yY u+mtyjvIbg9v2Ot3PDkqXjTHa2iEo0J9ObAgkbbzSl9p9j2aK9u2mg8Qq6j6keVwuGy1 PI5+B5+KEI7XCrqDtNZOh48toONEbTskQx/DIzDE5EiBFSrXEolidC9r3D8u3rsgwsDS JZjj4nkITZsbKM/AURXIzmjOhbmgscw5me/yZJZupSNHAZFDco3sglkfZXWOSbuErxSj mqYYWH1AEGQEFZe+lb3nZbnwk4Q46t+nE9Rt88CyOSFS6m+XADbiYLljjNdFjlhYlIRy Bnxg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=6jHUkktZYnLJuOeQ47HqdKglnmNwVQppeyvzohEh60E=; b=E3Xmra9voW0Fzg5E/LsnhzsccjmWTfqVeQLK1TJrzw4GqetL6l01HhRC5CY23Rc2MG 7aYjdGXrB1a855XOPtFqa1QuY8W4QBqdn4mn+kMPamDO+XaknK2DgPqyBi2lbI7JDdgp wVRng93VXgPKmjeosXxi3l80KgoWUiu9B1LksvdvUqy0eFl02c6iuLuB1EokbJ5TdIi8 JiHmiVsuhWMSkl20u+G6ENhgk0al+7RJsjN1hZKQjIAOL2oI/3N7Hj2UDDgsWvXtjrxs HtD8WZ0DV2myhwV+YVBGxfwfi2wYF3MIikhJsQDEedSDn+RuXC7Kpj29Ppgc3Tmr988n sllA== X-Gm-Message-State: AGi0PuYWsPT4a2+Vkoie8lgT8pvCIt1bSDIqa2OSDLPrBgFEKtZdJB0K DyGOlmbC5y/MRV8HEVW5tNMoai78L+s= X-Google-Smtp-Source: APiQypKviZ9567+jlzh79cNJ6g2InF7Sdo6NYY3WsjYqgIh8KYFj7B9dbw3YAfWPvDLTzocuUWrG0tnX9aM= X-Received: by 2002:a17:90a:cc10:: with SMTP id b16mr32757pju.29.1585777157804; Wed, 01 Apr 2020 14:39:17 -0700 (PDT) Date: Wed, 1 Apr 2020 14:39:02 -0700 In-Reply-To: <20200401213903.182112-1-dancol@google.com> Message-Id: <20200401213903.182112-3-dancol@google.com> Mime-Version: 1.0 References: <20200326200634.222009-1-dancol@google.com> <20200401213903.182112-1-dancol@google.com> X-Mailer: git-send-email 2.26.0.rc2.310.g2932bb562d-goog Subject: [PATCH v5 2/3] Teach SELinux about anonymous inodes From: Daniel Colascione To: timmurray@google.com, selinux@vger.kernel.org, linux-security-module@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, viro@zeniv.linux.org.uk, paul@paul-moore.com, nnk@google.com, sds@tycho.nsa.gov, lokeshgidra@google.com, jmorris@namei.org Cc: Daniel Colascione Sender: selinux-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: selinux@vger.kernel.org This change uses the anon_inodes and LSM infrastructure introduced in the previous patch to give SELinux the ability to control anonymous-inode files that are created using the new _secure() anon_inodes functions. A SELinux policy author detects and controls these anonymous inodes by adding a name-based type_transition rule that assigns a new security type to anonymous-inode files created in some domain. The name used for the name-based transition is the name associated with the anonymous inode for file listings --- e.g., "[userfaultfd]" or "[perf_event]". Example: type uffd_t; type_transition sysadm_t sysadm_t : anon_inode uffd_t "[userfaultfd]"; allow sysadm_t uffd_t:anon_inode { create }; (The next patch in this series is necessary for making userfaultfd support this new interface. The example above is just for exposition.) Signed-off-by: Daniel Colascione --- security/selinux/hooks.c | 53 +++++++++++++++++++++++++++++ security/selinux/include/classmap.h | 2 ++ 2 files changed, 55 insertions(+) diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index 1659b59fb5d7..6f7222d2e404 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -2915,6 +2915,58 @@ static int selinux_inode_init_security(struct inode *inode, struct inode *dir, return 0; } +static int selinux_inode_init_security_anon(struct inode *inode, + const struct qstr *name, + const struct inode *context_inode) +{ + const struct task_security_struct *tsec = selinux_cred(current_cred()); + struct common_audit_data ad; + struct inode_security_struct *isec; + int rc; + + if (unlikely(!selinux_state.initialized)) + return 0; + + isec = selinux_inode(inode); + + /* + * We only get here once per ephemeral inode. The inode has + * been initialized via inode_alloc_security but is otherwise + * untouched. + */ + + if (context_inode) { + struct inode_security_struct *context_isec = + selinux_inode(context_inode); + isec->sclass = context_isec->sclass; + isec->sid = context_isec->sid; + } else { + isec->sclass = SECCLASS_ANON_INODE; + rc = security_transition_sid( + &selinux_state, tsec->sid, tsec->sid, + isec->sclass, name, &isec->sid); + if (rc) + return rc; + } + + isec->initialized = LABEL_INITIALIZED; + + /* + * Now that we've initialized security, check whether we're + * allowed to actually create this type of anonymous inode. + */ + + ad.type = LSM_AUDIT_DATA_INODE; + ad.u.inode = inode; + + return avc_has_perm(&selinux_state, + tsec->sid, + isec->sid, + isec->sclass, + FILE__CREATE, + &ad); +} + static int selinux_inode_create(struct inode *dir, struct dentry *dentry, umode_t mode) { return may_create(dir, dentry, SECCLASS_FILE); @@ -6923,6 +6975,7 @@ static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = { LSM_HOOK_INIT(inode_free_security, selinux_inode_free_security), LSM_HOOK_INIT(inode_init_security, selinux_inode_init_security), + LSM_HOOK_INIT(inode_init_security_anon, selinux_inode_init_security_anon), LSM_HOOK_INIT(inode_create, selinux_inode_create), LSM_HOOK_INIT(inode_link, selinux_inode_link), LSM_HOOK_INIT(inode_unlink, selinux_inode_unlink), diff --git a/security/selinux/include/classmap.h b/security/selinux/include/classmap.h index 986f3ac14282..263750b6aaac 100644 --- a/security/selinux/include/classmap.h +++ b/security/selinux/include/classmap.h @@ -248,6 +248,8 @@ struct security_class_mapping secclass_map[] = { {"open", "cpu", "kernel", "tracepoint", "read", "write"} }, { "lockdown", { "integrity", "confidentiality", NULL } }, + { "anon_inode", + { COMMON_FILE_PERMS, NULL } }, { NULL } };