From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Paris Subject: [PATCH 11/20] fanotify: limit the number of marks in a single fanotify group Date: Thu, 28 Oct 2010 17:32:38 -0400 Message-ID: <20101028213238.24810.11702.stgit@paris.rdu.redhat.com> References: <20101028213139.24810.34058.stgit@paris.rdu.redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Cc: agruen@suse.de, tvrtko.ursulin@sophos.com To: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org Return-path: Received: from mx1.redhat.com ([209.132.183.28]:35346 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760641Ab0J1Vcm (ORCPT ); Thu, 28 Oct 2010 17:32:42 -0400 In-Reply-To: <20101028213139.24810.34058.stgit@paris.rdu.redhat.com> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: There is currently no limit on the number of marks a given fanotify group can have. Since fanotify is gated on CAP_SYS_ADMIN this was not seen as a serious DoS threat. This patch implements a default of 8192, the same as inotify to work towards removing the CAP_SYS_ADMIN gating and eliminating the default DoS'able status. Signed-off-by: Eric Paris --- fs/notify/fanotify/fanotify_user.c | 9 +++++++++ include/linux/fsnotify_backend.h | 1 + 2 files changed, 10 insertions(+), 0 deletions(-) diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c index 43d66d9..1d33d7d 100644 --- a/fs/notify/fanotify/fanotify_user.c +++ b/fs/notify/fanotify/fanotify_user.c @@ -17,6 +17,7 @@ #include #define FANOTIFY_DEFAULT_MAX_EVENTS 16384 +#define FANOTIFY_DEFAULT_MAX_MARKS 8192 extern const struct fsnotify_ops fanotify_fsnotify_ops; @@ -584,6 +585,9 @@ static int fanotify_add_vfsmount_mark(struct fsnotify_group *group, if (!fsn_mark) { int ret; + if (atomic_read(&group->num_marks) > group->fanotify_data.max_marks) + return -ENOSPC; + fsn_mark = kmem_cache_alloc(fanotify_mark_cache, GFP_KERNEL); if (!fsn_mark) return -ENOMEM; @@ -626,6 +630,9 @@ static int fanotify_add_inode_mark(struct fsnotify_group *group, if (!fsn_mark) { int ret; + if (atomic_read(&group->num_marks) > group->fanotify_data.max_marks) + return -ENOSPC; + fsn_mark = kmem_cache_alloc(fanotify_mark_cache, GFP_KERNEL); if (!fsn_mark) return -ENOMEM; @@ -700,6 +707,8 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags) group->max_events = FANOTIFY_DEFAULT_MAX_EVENTS; } + group->fanotify_data.max_marks = FANOTIFY_DEFAULT_MAX_MARKS; + fd = anon_inode_getfd("[fanotify]", &fanotify_fops, group, f_flags); if (fd < 0) goto out_put_group; diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h index b37f3a7..49ceed6 100644 --- a/include/linux/fsnotify_backend.h +++ b/include/linux/fsnotify_backend.h @@ -169,6 +169,7 @@ struct fsnotify_group { bool bypass_perm; /* protected by access_mutex */ #endif /* CONFIG_FANOTIFY_ACCESS_PERMISSIONS */ int f_flags; + unsigned int max_marks; } fanotify_data; #endif /* CONFIG_FANOTIFY */ };