From patchwork Thu Jul 17 18:08:34 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kees Cook X-Patchwork-Id: 4577971 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork1.web.kernel.org (Postfix) with ESMTP id CBB169F1D6 for ; Thu, 17 Jul 2014 18:13:50 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id CE70420117 for ; Thu, 17 Jul 2014 18:13:49 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.9]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id CC9BA2010B for ; Thu, 17 Jul 2014 18:13:48 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1X7q9S-0003Vh-CN; Thu, 17 Jul 2014 18:11:30 +0000 Received: from smtp.outflux.net ([2001:19d0:2:6:c0de:0:736d:7470]) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1X7q7V-0008FJ-VD for linux-arm-kernel@lists.infradead.org; Thu, 17 Jul 2014 18:09:30 +0000 Received: from www.outflux.net (serenity.outflux.net [10.2.0.2]) by vinyl.outflux.net (8.14.4/8.14.4/Debian-4.1ubuntu1) with ESMTP id s6HI8lfh032248; Thu, 17 Jul 2014 11:08:48 -0700 From: Kees Cook To: linux-kernel@vger.kernel.org Subject: [PATCH v12 07/11] sched: move no_new_privs into new atomic flags Date: Thu, 17 Jul 2014 11:08:34 -0700 Message-Id: <1405620518-18495-8-git-send-email-keescook@chromium.org> X-Mailer: git-send-email 1.7.9.5 In-Reply-To: <1405620518-18495-1-git-send-email-keescook@chromium.org> References: <1405620518-18495-1-git-send-email-keescook@chromium.org> X-MIMEDefang-Filter: outflux$Revision: 1.316 $ X-HELO: www.outflux.net X-Scanned-By: MIMEDefang 2.73 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20140717_110930_059570_52854104 X-CRM114-Status: GOOD ( 14.62 ) X-Spam-Score: -0.0 (/) Cc: linux-arch@vger.kernel.org, linux-mips@linux-mips.org, Will Drewry , Kees Cook , linux-api@vger.kernel.org, x86@kernel.org, Oleg Nesterov , Andy Lutomirski , linux-security-module@vger.kernel.org, Julien Tinnes , "Michael Kerrisk \(man-pages\)" , James Morris , David Drysdale , linux-arm-kernel@lists.infradead.org X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Since seccomp transitions between threads requires updates to the no_new_privs flag to be atomic, the flag must be part of an atomic flag set. This moves the nnp flag into a separate task field, and introduces accessors. Signed-off-by: Kees Cook Reviewed-by: Oleg Nesterov Reviewed-by: Andy Lutomirski --- fs/exec.c | 4 ++-- include/linux/sched.h | 18 +++++++++++++++--- kernel/seccomp.c | 2 +- kernel/sys.c | 4 ++-- security/apparmor/domain.c | 4 ++-- 5 files changed, 22 insertions(+), 10 deletions(-) diff --git a/fs/exec.c b/fs/exec.c index a3d33fe592d6..0f5c272410f6 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -1234,7 +1234,7 @@ static void check_unsafe_exec(struct linux_binprm *bprm) * This isn't strictly necessary, but it makes it harder for LSMs to * mess up. */ - if (current->no_new_privs) + if (task_no_new_privs(current)) bprm->unsafe |= LSM_UNSAFE_NO_NEW_PRIVS; t = p; @@ -1272,7 +1272,7 @@ int prepare_binprm(struct linux_binprm *bprm) bprm->cred->egid = current_egid(); if (!(bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID) && - !current->no_new_privs && + !task_no_new_privs(current) && kuid_has_mapping(bprm->cred->user_ns, inode->i_uid) && kgid_has_mapping(bprm->cred->user_ns, inode->i_gid)) { /* Set-uid? */ diff --git a/include/linux/sched.h b/include/linux/sched.h index 0376b054a0d0..45cec6b70eaf 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1307,13 +1307,12 @@ struct task_struct { * execve */ unsigned in_iowait:1; - /* task may not gain privileges */ - unsigned no_new_privs:1; - /* Revert to default priority/policy when forking */ unsigned sched_reset_on_fork:1; unsigned sched_contributes_to_load:1; + unsigned long atomic_flags; /* Flags needing atomic access. */ + pid_t pid; pid_t tgid; @@ -1967,6 +1966,19 @@ static inline void memalloc_noio_restore(unsigned int flags) current->flags = (current->flags & ~PF_MEMALLOC_NOIO) | flags; } +/* Per-process atomic flags. */ +#define PFA_NO_NEW_PRIVS 0x00000001 /* May not gain new privileges. */ + +static inline bool task_no_new_privs(struct task_struct *p) +{ + return test_bit(PFA_NO_NEW_PRIVS, &p->atomic_flags); +} + +static inline void task_set_no_new_privs(struct task_struct *p) +{ + set_bit(PFA_NO_NEW_PRIVS, &p->atomic_flags); +} + /* * task->jobctl flags */ diff --git a/kernel/seccomp.c b/kernel/seccomp.c index f0652578af75..d2596136b0d1 100644 --- a/kernel/seccomp.c +++ b/kernel/seccomp.c @@ -241,7 +241,7 @@ static long seccomp_attach_filter(struct sock_fprog *fprog) * This avoids scenarios where unprivileged tasks can affect the * behavior of privileged children. */ - if (!current->no_new_privs && + if (!task_no_new_privs(current) && security_capable_noaudit(current_cred(), current_user_ns(), CAP_SYS_ADMIN) != 0) return -EACCES; diff --git a/kernel/sys.c b/kernel/sys.c index 66a751ebf9d9..ce8129192a26 100644 --- a/kernel/sys.c +++ b/kernel/sys.c @@ -1990,12 +1990,12 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3, if (arg2 != 1 || arg3 || arg4 || arg5) return -EINVAL; - current->no_new_privs = 1; + task_set_no_new_privs(current); break; case PR_GET_NO_NEW_PRIVS: if (arg2 || arg3 || arg4 || arg5) return -EINVAL; - return current->no_new_privs ? 1 : 0; + return task_no_new_privs(current) ? 1 : 0; case PR_GET_THP_DISABLE: if (arg2 || arg3 || arg4 || arg5) return -EINVAL; diff --git a/security/apparmor/domain.c b/security/apparmor/domain.c index 452567d3a08e..d97cba3e3849 100644 --- a/security/apparmor/domain.c +++ b/security/apparmor/domain.c @@ -621,7 +621,7 @@ int aa_change_hat(const char *hats[], int count, u64 token, bool permtest) * There is no exception for unconfined as change_hat is not * available. */ - if (current->no_new_privs) + if (task_no_new_privs(current)) return -EPERM; /* released below */ @@ -776,7 +776,7 @@ int aa_change_profile(const char *ns_name, const char *hname, bool onexec, * no_new_privs is set because this aways results in a reduction * of permissions. */ - if (current->no_new_privs && !unconfined(profile)) { + if (task_no_new_privs(current) && !unconfined(profile)) { put_cred(cred); return -EPERM; }