Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760679AbaGYNut (ORCPT ); Fri, 25 Jul 2014 09:50:49 -0400 Received: from mail-wg0-f73.google.com ([74.125.82.73]:39922 "EHLO mail-wg0-f73.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760410AbaGYNsQ (ORCPT ); Fri, 25 Jul 2014 09:48:16 -0400 From: David Drysdale To: linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, Greg Kroah-Hartman Cc: Alexander Viro , Meredydd Luff , Kees Cook , James Morris , Andy Lutomirski , Paolo Bonzini , Paul Moore , Christoph Hellwig , linux-api@vger.kernel.org, David Drysdale Subject: [PATCH 10/11] capsicum: prctl(2) to force use of O_BENEATH Date: Fri, 25 Jul 2014 14:47:06 +0100 Message-Id: <1406296033-32693-11-git-send-email-drysdale@google.com> X-Mailer: git-send-email 2.0.0.526.g5318336 In-Reply-To: <1406296033-32693-1-git-send-email-drysdale@google.com> References: <1406296033-32693-1-git-send-email-drysdale@google.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Add a per-task flag that indicates all openat(2) operations should implicitly have the O_BENEATH flag set. Add a prctl(2) command to set this flag (irrevocably). Include an option to force the flag set to be synchronized across all tasks in the thread group. Signed-off-by: David Drysdale --- fs/namei.c | 3 +++ include/linux/sched.h | 3 +++ include/uapi/linux/prctl.h | 14 ++++++++++++++ kernel/sys.c | 28 ++++++++++++++++++++++++++++ 4 files changed, 48 insertions(+) diff --git a/fs/namei.c b/fs/namei.c index fe03a7dd7537..5d3b440869df 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -1849,6 +1849,9 @@ static int path_init(int dfd, const char *name, unsigned int *flags, nd->flags = (*flags) | LOOKUP_PARENT | LOOKUP_JUMPED; nd->depth = 0; + if (current->openat_beneath) + *flags |= LOOKUP_BENEATH; + if ((*flags) & LOOKUP_ROOT) { struct dentry *root = nd->root.dentry; struct inode *inode = root->d_inode; diff --git a/include/linux/sched.h b/include/linux/sched.h index 306f4f0c987a..8d2943879b7b 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1303,6 +1303,9 @@ struct task_struct { /* Used for emulating ABI behavior of previous Linux versions */ unsigned int personality; + /* Indicate that openat(2) operations implictly have O_BENEATH */ + unsigned openat_beneath:1; + unsigned in_execve:1; /* Tell the LSMs that the process is doing an * execve */ unsigned in_iowait:1; diff --git a/include/uapi/linux/prctl.h b/include/uapi/linux/prctl.h index 58afc04c107e..b34fb2bbdaf8 100644 --- a/include/uapi/linux/prctl.h +++ b/include/uapi/linux/prctl.h @@ -152,4 +152,18 @@ #define PR_SET_THP_DISABLE 41 #define PR_GET_THP_DISABLE 42 +/* + * If openat_beneath is set for a task, then all openat(2) operations will + * implicitly have the O_BENEATH flag set for them. Once set, this flag cannot + * be cleared. + */ +#define PR_SET_OPENAT_BENEATH 44 +#define PR_GET_OPENAT_BENEATH 45 + +/* + Indicate that the openat_beneath flag should be synchronized across all + * threads in the process. + */ +#define PR_SET_OPENAT_BENEATH_TSYNC 0x01 + #endif /* _LINUX_PRCTL_H */ diff --git a/kernel/sys.c b/kernel/sys.c index 8d8ccf6cfb38..cf2530c41982 100644 --- a/kernel/sys.c +++ b/kernel/sys.c @@ -1821,6 +1821,23 @@ out: return error; } +static int prctl_set_openat_beneath(struct task_struct *me, unsigned long flags) +{ + me->openat_beneath = 1; + if (flags & PR_SET_OPENAT_BENEATH_TSYNC) { + struct task_struct *thread, *caller; + unsigned long tflags; + + write_lock_irqsave(&tasklist_lock, tflags); + thread = caller = me; + while_each_thread(caller, thread) { + thread->openat_beneath = 1; + } + write_unlock_irqrestore(&tasklist_lock, tflags); + } + return 0; +} + #ifdef CONFIG_CHECKPOINT_RESTORE static int prctl_get_tid_address(struct task_struct *me, int __user **tid_addr) { @@ -1996,6 +2013,17 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3, if (arg2 || arg3 || arg4 || arg5) return -EINVAL; return current->no_new_privs ? 1 : 0; + case PR_SET_OPENAT_BENEATH: + if (arg2 != 1 || arg4 || arg5) + return -EINVAL; + if ((arg3 & ~(PR_SET_OPENAT_BENEATH_TSYNC)) != 0) + return -EINVAL; + error = prctl_set_openat_beneath(me, arg3); + break; + case PR_GET_OPENAT_BENEATH: + if (arg2 || arg3 || arg4 || arg5) + return -EINVAL; + return me->openat_beneath; case PR_GET_THP_DISABLE: if (arg2 || arg3 || arg4 || arg5) return -EINVAL; -- 2.0.0.526.g5318336 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/