From patchwork Mon Jun 13 20:28:07 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Micah Morton X-Patchwork-Id: 12880208 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 B6670C43334 for ; Mon, 13 Jun 2022 20:56:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S245594AbiFMU4i (ORCPT ); Mon, 13 Jun 2022 16:56:38 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36726 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1345169AbiFMUzf (ORCPT ); Mon, 13 Jun 2022 16:55:35 -0400 Received: from mail-pj1-x102a.google.com (mail-pj1-x102a.google.com [IPv6:2607:f8b0:4864:20::102a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D4A121274D for ; Mon, 13 Jun 2022 13:28:12 -0700 (PDT) Received: by mail-pj1-x102a.google.com with SMTP id k12-20020a17090a404c00b001eaabc1fe5dso4005842pjg.1 for ; Mon, 13 Jun 2022 13:28:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=osZI55S/5dMcmV9pE2V+C0A43bBMSnu9K9IPGFv9W/Q=; b=mWUznRIloP2KlmQ1d/y4w2DVizn3o5dRam9GxBJuSDKWWJyNFWl8lbPbBDxPFrlLYF bL6KsouwqNO7nn0ZucMLrpAvQeeMlv6Lz+ixXEBs2F9gtF6UMucw2rUHLthFUr17mVkI 9R2z0NFBWgYL9bSujjUguW3v3dnYtOlRyA60Q= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=osZI55S/5dMcmV9pE2V+C0A43bBMSnu9K9IPGFv9W/Q=; b=oJMkOw0I02JjcW2tK5XZcirHg07zV/KhgXKamC+S7bAT48QumnhYJ8p70LW3wmw+Ms M49pOsQIN+/ijPifDOcwlG22eeOjEh7knvkBYXCaKvRWq0VKbLWMCi1EHtWSguTN80Nb dOkNx3PUQV53POIGe38abwZDFP9G41FwSqSbxlAJzQe3jQZ58rOPE7D5ztcmlMspIO57 H3mtcyhKCg6cv2BXt/kSsnUQEPznIitI4Wxa3XtjMABsmJkWQLJnvNhdri0Km09ESPkm z5S36JxQyXr/kAaI1Aqqqg9qn90DTpdCe/XxHofQOVwcPZ6zT/2iQCVzKF71SzxIiYBj 1Uew== X-Gm-Message-State: AJIora8nQucn7Kw6y5G8pEZrf/LucG1rmjehEUAWx8JrjalZNdSXN2f4 hetUI1WZWvzbprn9T892EVtz91JLKYQsjQ== X-Google-Smtp-Source: ABdhPJwWHXAV5GrU0wvTAGyjLfVkRBvo2yWyHFPTojpJxd+BGIwMV6Tfi1FuKAqpnzhRjLbV0+62Vg== X-Received: by 2002:a17:902:eb90:b0:163:e4c1:b2fc with SMTP id q16-20020a170902eb9000b00163e4c1b2fcmr807340plg.159.1655152092015; Mon, 13 Jun 2022 13:28:12 -0700 (PDT) Received: from localhost ([2620:15c:202:200:cf79:20b3:87b5:90bc]) by smtp.gmail.com with UTF8SMTPSA id f13-20020a170902f38d00b0016413dbbf92sm5531140ple.234.2022.06.13.13.28.10 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 13 Jun 2022 13:28:10 -0700 (PDT) From: Micah Morton To: linux-security-module@vger.kernel.org Cc: keescook@chromium.org, jmorris@namei.org, serge@hallyn.com, linux-kernel@vger.kernel.org, Micah Morton Subject: [PATCH 1/2] security: Add LSM hook to setgroups() syscall Date: Mon, 13 Jun 2022 13:28:07 -0700 Message-Id: <20220613202807.447694-1-mortonm@chromium.org> X-Mailer: git-send-email 2.36.1.476.g0c4daa206d-goog MIME-Version: 1.0 Precedence: bulk List-ID: Give the LSM framework the ability to filter setgroups() syscalls. There are already analagous hooks for the set*uid() and set*gid() syscalls. The SafeSetID LSM will use this new hook to ensure setgroups() calls are allowed by the installed security policy. Signed-off-by: Micah Morton Reported-by: kernel test robot Reported-by: kernel test robot Reported-by: kernel test robot --- Developed on 5.18 include/linux/lsm_hook_defs.h | 1 + include/linux/lsm_hooks.h | 7 +++++++ include/linux/security.h | 7 +++++++ kernel/groups.c | 12 ++++++++++++ security/security.c | 5 +++++ 5 files changed, 32 insertions(+) diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h index db924fe379c9..c01063ec4be7 100644 --- a/include/linux/lsm_hook_defs.h +++ b/include/linux/lsm_hook_defs.h @@ -201,6 +201,7 @@ LSM_HOOK(int, 0, task_fix_setuid, struct cred *new, const struct cred *old, int flags) LSM_HOOK(int, 0, task_fix_setgid, struct cred *new, const struct cred * old, int flags) +LSM_HOOK(int, 0, task_fix_setgroups, struct cred *new, const struct cred * old) LSM_HOOK(int, 0, task_setpgid, struct task_struct *p, pid_t pgid) LSM_HOOK(int, 0, task_getpgid, struct task_struct *p) LSM_HOOK(int, 0, task_getsid, struct task_struct *p) diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h index 419b5febc3ca..b5143d9a1127 100644 --- a/include/linux/lsm_hooks.h +++ b/include/linux/lsm_hooks.h @@ -701,6 +701,13 @@ * @old is the set of credentials that are being replaced. * @flags contains one of the LSM_SETID_* values. * Return 0 on success. + * @task_fix_setgroups: + * Update the module's state after setting the supplementary group + * identity attributes of the current process. + * @new is the set of credentials that will be installed. Modifications + * should be made to this rather than to @current->cred. + * @old is the set of credentials that are being replaced. + * Return 0 on success. * @task_setpgid: * Check permission before setting the process group identifier of the * process @p to @pgid. diff --git a/include/linux/security.h b/include/linux/security.h index 25b3ef71f495..d111ff830742 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -413,6 +413,7 @@ int security_task_fix_setuid(struct cred *new, const struct cred *old, int flags); int security_task_fix_setgid(struct cred *new, const struct cred *old, int flags); +int security_task_fix_setgroups(struct cred *new, const struct cred *old); int security_task_setpgid(struct task_struct *p, pid_t pgid); int security_task_getpgid(struct task_struct *p); int security_task_getsid(struct task_struct *p); @@ -1096,6 +1097,12 @@ static inline int security_task_fix_setgid(struct cred *new, return 0; } +static inline int security_task_fix_setgroups(struct cred *new, + const struct cred *old) +{ + return 0; +} + static inline int security_task_setpgid(struct task_struct *p, pid_t pgid) { return 0; diff --git a/kernel/groups.c b/kernel/groups.c index 787b381c7c00..c085f54d8dbb 100644 --- a/kernel/groups.c +++ b/kernel/groups.c @@ -134,13 +134,25 @@ EXPORT_SYMBOL(set_groups); int set_current_groups(struct group_info *group_info) { struct cred *new; + struct cred *old; new = prepare_creds(); if (!new) return -ENOMEM; + old = current_cred(); + set_groups(new, group_info); + + retval = security_task_fix_setgroups(new, old); + if (retval < 0) + goto error; + return commit_creds(new); + +error: + abort_creds(new); + return retval; } EXPORT_SYMBOL(set_current_groups); diff --git a/security/security.c b/security/security.c index b7cf5cbfdc67..eaed8d16d90a 100644 --- a/security/security.c +++ b/security/security.c @@ -1809,6 +1809,11 @@ int security_task_fix_setgid(struct cred *new, const struct cred *old, return call_int_hook(task_fix_setgid, 0, new, old, flags); } +int security_task_fix_setgroups(struct cred *new, const struct cred *old) +{ + return call_int_hook(task_fix_setgroups, 0, new, old); +} + int security_task_setpgid(struct task_struct *p, pid_t pgid) { return call_int_hook(task_setpgid, 0, p, pgid);