From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755898AbYJNU57 (ORCPT ); Tue, 14 Oct 2008 16:57:59 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755207AbYJNUxL (ORCPT ); Tue, 14 Oct 2008 16:53:11 -0400 Received: from mx2.redhat.com ([66.187.237.31]:37843 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755203AbYJNUxK (ORCPT ); Tue, 14 Oct 2008 16:53:10 -0400 From: Eric Paris Subject: [PATCH -v2 13/16] fanotify: ability for userspace to delay responses To: linux-kernel@vger.kernel.org, malware-list@lists.printk.net Cc: viro@ZenIV.linux.org.uk, alan@lxorguk.ukuu.org.uk, arjan@infradead.org, greg@kroah.com, tytso@mit.edu Date: Tue, 14 Oct 2008 16:52:38 -0400 Message-ID: <20081014205238.1057.6024.stgit@paris.rdu.redhat.com> In-Reply-To: <20081014205009.1057.12041.stgit@paris.rdu.redhat.com> References: <20081014205009.1057.12041.stgit@paris.rdu.redhat.com> User-Agent: StGIT/0.14.3 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Userspace may know that it is behind, may know it is going to take a while to get a good response, or have any number of other reasons to block an access request. FAN_RESTTIMER will reset the timeout for an fanotify access decision response. Signed-off-by: Eric Paris --- fs/notify/access.c | 31 +++++++++++++++++++++++++++---- fs/notify/fanotify.h | 1 + fs/notify/notification.c | 2 ++ include/linux/fanotify.h | 1 + 4 files changed, 31 insertions(+), 4 deletions(-) diff --git a/fs/notify/access.c b/fs/notify/access.c index 6a2606c..5b3b32e 100644 --- a/fs/notify/access.c +++ b/fs/notify/access.c @@ -55,6 +55,8 @@ int fanotify_add_event_to_access(struct fanotify_group *group, struct fanotify_e int fanotify_get_response_from_access(struct fanotify_group *group, struct fanotify_event *event) { int ret; + +retry: ret = wait_event_interruptible_timeout(group->access_waitq, event->response, msecs_to_jiffies(5000)); @@ -89,13 +91,25 @@ int fanotify_get_response_from_access(struct fanotify_group *group, struct fanot } /* userspace responded, convert to something usable */ + spin_lock(&event->response_lock); switch (event->response) { case FAN_ALLOW: - return 0; + ret = 0; + break; case FAN_DENY: + ret = -EPERM; + break; + case FAN_RESETTIMER: + event->response = 0; + spin_unlock(&event->response_lock); + goto retry; default: - return -EPERM; + ret = -EPERM; + break; } + spin_unlock(&event->response_lock); + + return ret; } int fanotify_process_access_response(struct fanotify_group *group, unsigned long cookie, unsigned int response) @@ -108,7 +122,7 @@ int fanotify_process_access_response(struct fanotify_group *group, unsigned long * userspace can send a valid responce or we will clean it up after the * timeout */ - if (response & ~(FAN_ALLOW | FAN_DENY)) + if (response & ~(FAN_ALLOW | FAN_DENY | FAN_RESETTIMER)) return -EINVAL; mutex_lock(&group->access_mutex); @@ -117,6 +131,11 @@ int fanotify_process_access_response(struct fanotify_group *group, unsigned long continue; event = holder->event; + + /* FAN_RESETTIMER should be left on the list for later.... */ + if (response == FAN_RESETTIMER) + break; + spin_lock(&event->holder_spinlock); holder->event = NULL; /* as soon as we do this the event.holder might be reused */ @@ -132,9 +151,13 @@ int fanotify_process_access_response(struct fanotify_group *group, unsigned long if (!event) return -ENOENT; + spin_lock(&event->response_lock); event->response = response; + spin_unlock(&event->response_lock); wake_up(&group->access_waitq); - fanotify_put_event(event); + + if (response != FAN_RESETTIMER) + fanotify_put_event(event); return 0; } diff --git a/fs/notify/fanotify.h b/fs/notify/fanotify.h index e07703f..d65db61 100644 --- a/fs/notify/fanotify.h +++ b/fs/notify/fanotify.h @@ -48,6 +48,7 @@ struct fanotify_event { atomic_t refcnt; /* how many groups still are using/need to send this event */ /* if waiting for a userspace access answer this is the cookie they will send back */ unsigned long cookie; + spinlock_t response_lock; /* protects response */ unsigned int response; /* userspace answer to question */ }; diff --git a/fs/notify/notification.c b/fs/notify/notification.c index 89bb02c..dd0d2db 100644 --- a/fs/notify/notification.c +++ b/fs/notify/notification.c @@ -27,6 +27,7 @@ #include #include #include +#include #include #include "fanotify.h" @@ -169,6 +170,7 @@ struct fanotify_event *create_event(struct file *file, unsigned int mask) event->holder.event = NULL; INIT_LIST_HEAD(&event->holder.event_list); atomic_set(&event->refcnt, 1); + spin_lock_init(&event->response_lock); spin_lock_init(&event->holder_spinlock); diff --git a/include/linux/fanotify.h b/include/linux/fanotify.h index b5c9db9..a36bd6b 100644 --- a/include/linux/fanotify.h +++ b/include/linux/fanotify.h @@ -49,6 +49,7 @@ /* answers will need to be either allow or deny */ #define FAN_ALLOW 0x00000001 #define FAN_DENY 0x00000002 +#define FAN_RESETTIMER 0x00000004 #ifdef __KERNEL__ #include