From patchwork Wed Nov 10 23:00:35 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Todd Kjos X-Patchwork-Id: 12613543 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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D31A1C433EF for ; Wed, 10 Nov 2021 23:00:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BBA2C6108B for ; Wed, 10 Nov 2021 23:00:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234178AbhKJXDb (ORCPT ); Wed, 10 Nov 2021 18:03:31 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46454 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234103AbhKJXDb (ORCPT ); Wed, 10 Nov 2021 18:03:31 -0500 Received: from mail-yb1-xb4a.google.com (mail-yb1-xb4a.google.com [IPv6:2607:f8b0:4864:20::b4a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E0FB8C0613F5 for ; Wed, 10 Nov 2021 15:00:42 -0800 (PST) Received: by mail-yb1-xb4a.google.com with SMTP id v20-20020a25fc14000000b005c2109e5ad1so6283288ybd.9 for ; Wed, 10 Nov 2021 15:00:42 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=8jKHo6LkDfJBgYdfBBUOxhfO8NmOHuGW94z8DX0r0iQ=; b=oxaZtey+PF9VlR8kJVgxiFo4FP55Ky4nFgyky47FAZyLfQGIPXb3oZcsbGIn8S66qQ KFnDPw9my535mY8eNqnIxW+JGCEmBzH46Oh0hm7dsYEYZ1SvToSnA2lgDw40/q21Eyzk T83BTZLZ8JIzKoTcXOKiynH2NsRbVoLi1CP6eIWNGmw+9nrbBtobmIoIognxVDfcWOub dU1+lCwHPqDh7tTpuTUg5uDpZfgeu/JVn+FVeHTVXQdsJJ7h9c3HuuRDX7lViTaJthFa YKPRR311JK9yBgdcvhhPS4PNGF5NgyWJuH4rYTCSwlWu8BBIHlZYnt/0L8cBIV1+8TmD u0PQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=8jKHo6LkDfJBgYdfBBUOxhfO8NmOHuGW94z8DX0r0iQ=; b=IUIdVTRO2cT+U5U5Kzuc0/RYtFXWqxV9Qoyxh2MrBk8AVkl52XIRT4vDka3tCwtNXe GOqYdb/qznPy2asCGI197QFOnzcnS9XYnb3ZgOkdpetAMPcfTrHRSuqd6gN51HTkDLbh pAftgX0Uth8x60wp0Yt2xOGeghwecuPaFsOhzwLBuaLekrFYeb1uUL63CbspAmnf4KnX TlfvicetVx9TlvudPXs8vBK/dhV2ucYqtQmQcSjL2uo7UtIjo24rWpk/HAd1Mrpdqiz8 jyeq28ZYLwHdAk0DQmPfXk4++LeXOG+aaAgECRaUZAlVTShZ4iFZNJ1onxx3+zGYY7IQ UKuA== X-Gm-Message-State: AOAM5310rfVIGhJnnVtAmAsIFZoxuA6zvjjSjIySxFv5dmdDNJAxfAjo oqDXfDlPhSCjK0+u+FMLaqHcOSZNBA== X-Google-Smtp-Source: ABdhPJwhg0f6Xlw9dt2ppqZzCc4QtxTrl5BigmQKAVYCQGptcvwvYAbrMC1AJUzTBlYRGjRS+xWSVfKefw== X-Received: from tkjos-desktop.mtv.corp.google.com ([2620:15c:211:200:4a73:99b6:9694:8c4d]) (user=tkjos job=sendgmr) by 2002:a25:6602:: with SMTP id a2mr3376534ybc.242.1636585242138; Wed, 10 Nov 2021 15:00:42 -0800 (PST) Date: Wed, 10 Nov 2021 15:00:35 -0800 In-Reply-To: <20211110230036.3274365-1-tkjos@google.com> Message-Id: <20211110230036.3274365-2-tkjos@google.com> Mime-Version: 1.0 References: <20211110230036.3274365-1-tkjos@google.com> X-Mailer: git-send-email 2.34.0.rc0.344.g81b53c2807-goog Subject: [PATCH 5.10 2/3] binder: use cred instead of task for selinux checks From: Todd Kjos To: stable@vger.kernel.org, gregkh@linuxfoundation.org, arve@android.com, tkjos@android.com, maco@android.com, christian@brauner.io, jmorris@namei.org, serge@hallyn.com, paul@paul-moore.com, stephen.smalley.work@gmail.com, eparis@parisplace.org, keescook@chromium.org, jannh@google.com, jeffv@google.com, zohar@linux.ibm.com, linux-security-module@vger.kernel.org, selinux@vger.kernel.org, devel@driverdev.osuosl.org Cc: joel@joelfernandes.org, kernel-team@android.com, Todd Kjos , Casey Schaufler Precedence: bulk List-ID: commit 52f88693378a58094c538662ba652aff0253c4fe upstream. Since binder was integrated with selinux, it has passed 'struct task_struct' associated with the binder_proc to represent the source and target of transactions. The conversion of task to SID was then done in the hook implementations. It turns out that there are race conditions which can result in an incorrect security context being used. Fix by using the 'struct cred' saved during binder_open and pass it to the selinux subsystem. Cc: stable@vger.kernel.org # 5.14 (need backport for earlier stables) Fixes: 79af73079d75 ("Add security hooks to binder and implement the hooks for SELinux.") Suggested-by: Jann Horn Signed-off-by: Todd Kjos Acked-by: Casey Schaufler Signed-off-by: Paul Moore Change-Id: Id7157515d2b08f11683aeb8ad9b8f1da075d34e7 --- drivers/android/binder.c | 12 ++++++------ include/linux/lsm_hook_defs.h | 14 +++++++------- include/linux/lsm_hooks.h | 14 +++++++------- include/linux/security.h | 28 +++++++++++++-------------- security/security.c | 14 +++++++------- security/selinux/hooks.c | 36 +++++++++++++++-------------------- 6 files changed, 56 insertions(+), 62 deletions(-) diff --git a/drivers/android/binder.c b/drivers/android/binder.c index 4e33f6e42ac4..50fff726dc70 100644 --- a/drivers/android/binder.c +++ b/drivers/android/binder.c @@ -2444,7 +2444,7 @@ static int binder_translate_binder(struct flat_binder_object *fp, ret = -EINVAL; goto done; } - if (security_binder_transfer_binder(proc->tsk, target_proc->tsk)) { + if (security_binder_transfer_binder(proc->cred, target_proc->cred)) { ret = -EPERM; goto done; } @@ -2490,7 +2490,7 @@ static int binder_translate_handle(struct flat_binder_object *fp, proc->pid, thread->pid, fp->handle); return -EINVAL; } - if (security_binder_transfer_binder(proc->tsk, target_proc->tsk)) { + if (security_binder_transfer_binder(proc->cred, target_proc->cred)) { ret = -EPERM; goto done; } @@ -2578,7 +2578,7 @@ static int binder_translate_fd(u32 fd, binder_size_t fd_offset, ret = -EBADF; goto err_fget; } - ret = security_binder_transfer_file(proc->tsk, target_proc->tsk, file); + ret = security_binder_transfer_file(proc->cred, target_proc->cred, file); if (ret < 0) { ret = -EPERM; goto err_security; @@ -2976,8 +2976,8 @@ static void binder_transaction(struct binder_proc *proc, return_error_line = __LINE__; goto err_invalid_target_handle; } - if (security_binder_transaction(proc->tsk, - target_proc->tsk) < 0) { + if (security_binder_transaction(proc->cred, + target_proc->cred) < 0) { return_error = BR_FAILED_REPLY; return_error_param = -EPERM; return_error_line = __LINE__; @@ -4918,7 +4918,7 @@ static int binder_ioctl_set_ctx_mgr(struct file *filp, ret = -EBUSY; goto out; } - ret = security_binder_set_context_mgr(proc->tsk); + ret = security_binder_set_context_mgr(proc->cred); if (ret < 0) goto out; if (uid_valid(context->binder_context_mgr_uid)) { diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h index 32a940117e7a..a6a3d4ddfc2d 100644 --- a/include/linux/lsm_hook_defs.h +++ b/include/linux/lsm_hook_defs.h @@ -26,13 +26,13 @@ * #undef LSM_HOOK * }; */ -LSM_HOOK(int, 0, binder_set_context_mgr, struct task_struct *mgr) -LSM_HOOK(int, 0, binder_transaction, struct task_struct *from, - struct task_struct *to) -LSM_HOOK(int, 0, binder_transfer_binder, struct task_struct *from, - struct task_struct *to) -LSM_HOOK(int, 0, binder_transfer_file, struct task_struct *from, - struct task_struct *to, struct file *file) +LSM_HOOK(int, 0, binder_set_context_mgr, const struct cred *mgr) +LSM_HOOK(int, 0, binder_transaction, const struct cred *from, + const struct cred *to) +LSM_HOOK(int, 0, binder_transfer_binder, const struct cred *from, + const struct cred *to) +LSM_HOOK(int, 0, binder_transfer_file, const struct cred *from, + const struct cred *to, struct file *file) LSM_HOOK(int, 0, ptrace_access_check, struct task_struct *child, unsigned int mode) LSM_HOOK(int, 0, ptrace_traceme, struct task_struct *parent) diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h index c503f7ab8afb..a8531b37e6f5 100644 --- a/include/linux/lsm_hooks.h +++ b/include/linux/lsm_hooks.h @@ -1288,22 +1288,22 @@ * * @binder_set_context_mgr: * Check whether @mgr is allowed to be the binder context manager. - * @mgr contains the task_struct for the task being registered. + * @mgr contains the struct cred for the current binder process. * Return 0 if permission is granted. * @binder_transaction: * Check whether @from is allowed to invoke a binder transaction call * to @to. - * @from contains the task_struct for the sending task. - * @to contains the task_struct for the receiving task. + * @from contains the struct cred for the sending process. + * @to contains the struct cred for the receiving process. * @binder_transfer_binder: * Check whether @from is allowed to transfer a binder reference to @to. - * @from contains the task_struct for the sending task. - * @to contains the task_struct for the receiving task. + * @from contains the struct cred for the sending process. + * @to contains the struct cred for the receiving process. * @binder_transfer_file: * Check whether @from is allowed to transfer @file to @to. - * @from contains the task_struct for the sending task. + * @from contains the struct cred for the sending process. * @file contains the struct file being transferred. - * @to contains the task_struct for the receiving task. + * @to contains the struct cred for the receiving process. * * @ptrace_access_check: * Check permission before allowing the current process to trace the diff --git a/include/linux/security.h b/include/linux/security.h index 7ef74d01b8e7..e67cc8c40865 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -254,13 +254,13 @@ extern int security_init(void); extern int early_security_init(void); /* Security operations */ -int security_binder_set_context_mgr(struct task_struct *mgr); -int security_binder_transaction(struct task_struct *from, - struct task_struct *to); -int security_binder_transfer_binder(struct task_struct *from, - struct task_struct *to); -int security_binder_transfer_file(struct task_struct *from, - struct task_struct *to, struct file *file); +int security_binder_set_context_mgr(const struct cred *mgr); +int security_binder_transaction(const struct cred *from, + const struct cred *to); +int security_binder_transfer_binder(const struct cred *from, + const struct cred *to); +int security_binder_transfer_file(const struct cred *from, + const struct cred *to, struct file *file); int security_ptrace_access_check(struct task_struct *child, unsigned int mode); int security_ptrace_traceme(struct task_struct *parent); int security_capget(struct task_struct *target, @@ -493,25 +493,25 @@ static inline int early_security_init(void) return 0; } -static inline int security_binder_set_context_mgr(struct task_struct *mgr) +static inline int security_binder_set_context_mgr(const struct cred *mgr) { return 0; } -static inline int security_binder_transaction(struct task_struct *from, - struct task_struct *to) +static inline int security_binder_transaction(const struct cred *from, + const struct cred *to) { return 0; } -static inline int security_binder_transfer_binder(struct task_struct *from, - struct task_struct *to) +static inline int security_binder_transfer_binder(const struct cred *from, + const struct cred *to) { return 0; } -static inline int security_binder_transfer_file(struct task_struct *from, - struct task_struct *to, +static inline int security_binder_transfer_file(const struct cred *from, + const struct cred *to, struct file *file) { return 0; diff --git a/security/security.c b/security/security.c index 1c696bce8e1c..a864ff824dd3 100644 --- a/security/security.c +++ b/security/security.c @@ -723,25 +723,25 @@ static void __init lsm_early_task(struct task_struct *task) /* Security operations */ -int security_binder_set_context_mgr(struct task_struct *mgr) +int security_binder_set_context_mgr(const struct cred *mgr) { return call_int_hook(binder_set_context_mgr, 0, mgr); } -int security_binder_transaction(struct task_struct *from, - struct task_struct *to) +int security_binder_transaction(const struct cred *from, + const struct cred *to) { return call_int_hook(binder_transaction, 0, from, to); } -int security_binder_transfer_binder(struct task_struct *from, - struct task_struct *to) +int security_binder_transfer_binder(const struct cred *from, + const struct cred *to) { return call_int_hook(binder_transfer_binder, 0, from, to); } -int security_binder_transfer_file(struct task_struct *from, - struct task_struct *to, struct file *file) +int security_binder_transfer_file(const struct cred *from, + const struct cred *to, struct file *file) { return call_int_hook(binder_transfer_file, 0, from, to, file); } diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index 227eb8967963..f32026bc96b4 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -2004,22 +2004,19 @@ static inline u32 open_file_to_av(struct file *file) /* Hook functions begin here. */ -static int selinux_binder_set_context_mgr(struct task_struct *mgr) +static int selinux_binder_set_context_mgr(const struct cred *mgr) { - u32 mysid = current_sid(); - u32 mgrsid = task_sid(mgr); - return avc_has_perm(&selinux_state, - mysid, mgrsid, SECCLASS_BINDER, + current_sid(), cred_sid(mgr), SECCLASS_BINDER, BINDER__SET_CONTEXT_MGR, NULL); } -static int selinux_binder_transaction(struct task_struct *from, - struct task_struct *to) +static int selinux_binder_transaction(const struct cred *from, + const struct cred *to) { u32 mysid = current_sid(); - u32 fromsid = task_sid(from); - u32 tosid = task_sid(to); + u32 fromsid = cred_sid(from); + u32 tosid = cred_sid(to); int rc; if (mysid != fromsid) { @@ -2030,27 +2027,24 @@ static int selinux_binder_transaction(struct task_struct *from, return rc; } - return avc_has_perm(&selinux_state, - fromsid, tosid, SECCLASS_BINDER, BINDER__CALL, - NULL); + return avc_has_perm(&selinux_state, fromsid, tosid, + SECCLASS_BINDER, BINDER__CALL, NULL); } -static int selinux_binder_transfer_binder(struct task_struct *from, - struct task_struct *to) +static int selinux_binder_transfer_binder(const struct cred *from, + const struct cred *to) { - u32 fromsid = task_sid(from); - u32 tosid = task_sid(to); - return avc_has_perm(&selinux_state, - fromsid, tosid, SECCLASS_BINDER, BINDER__TRANSFER, + cred_sid(from), cred_sid(to), + SECCLASS_BINDER, BINDER__TRANSFER, NULL); } -static int selinux_binder_transfer_file(struct task_struct *from, - struct task_struct *to, +static int selinux_binder_transfer_file(const struct cred *from, + const struct cred *to, struct file *file) { - u32 sid = task_sid(to); + u32 sid = cred_sid(to); struct file_security_struct *fsec = selinux_file(file); struct dentry *dentry = file->f_path.dentry; struct inode_security_struct *isec;