From 9e66e4233db9c7e31e9ee706be2c9ddd54cf99b3 Mon Sep 17 00:00:00 2001 From: Eric Paris Date: Thu, 17 Dec 2009 21:24:34 -0500 Subject: fanotify: permissions and blocking This is the backend work needed for fanotify to support the new FS_OPEN_PERM and FS_ACCESS_PERM fsnotify events. This is done using the new fsnotify secondary queue. No userspace interface is provided actually respond to or request these events. Signed-off-by: Eric Paris --- fs/notify/fanotify/Kconfig | 14 ++++++++++ fs/notify/fanotify/fanotify.c | 54 +++++++++++++++++++++++++++++++++++--- fs/notify/fanotify/fanotify_user.c | 5 ++++ 3 files changed, 69 insertions(+), 4 deletions(-) (limited to 'fs/notify') diff --git a/fs/notify/fanotify/Kconfig b/fs/notify/fanotify/Kconfig index 668e5df28e28..566de30395c2 100644 --- a/fs/notify/fanotify/Kconfig +++ b/fs/notify/fanotify/Kconfig @@ -10,3 +10,17 @@ config FANOTIFY the event. If unsure, say Y. + +config FANOTIFY_ACCESS_PERMISSIONS + bool "fanotify permissions checking" + depends on FANOTIFY + depends on SECURITY + default n + ---help--- + Say Y here is you want fanotify listeners to be able to make permissions + decisions concerning filesystem events. This is used by some fanotify + listeners which need to scan files before allowing the system access to + use those files. This is used by some anti-malware vendors and by some + hierarchical storage managent systems. + + If unsure, say N. diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c index 4feed8601e29..52d0a55a249e 100644 --- a/fs/notify/fanotify/fanotify.c +++ b/fs/notify/fanotify/fanotify.c @@ -2,9 +2,12 @@ #include #include #include +#include #include /* UINT_MAX */ #include +#include #include +#include static bool should_merge(struct fsnotify_event *old, struct fsnotify_event *new) { @@ -88,10 +91,37 @@ out: return ret; } +#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS +static int fanotify_get_response_from_access(struct fsnotify_group *group, + struct fsnotify_event *event) +{ + int ret; + + pr_debug("%s: group=%p event=%p\n", __func__, group, event); + + wait_event(group->fanotify_data.access_waitq, event->response); + + /* userspace responded, convert to something usable */ + spin_lock(&event->lock); + switch (event->response) { + case FAN_ALLOW: + ret = 0; + break; + case FAN_DENY: + default: + ret = -EPERM; + } + event->response = 0; + spin_unlock(&event->lock); + + return ret; +} +#endif + static int fanotify_handle_event(struct fsnotify_group *group, struct fsnotify_event *event) { int ret; - struct fsnotify_event *used_event; + struct fsnotify_event *notify_event = NULL; BUILD_BUG_ON(FAN_ACCESS != FS_ACCESS); BUILD_BUG_ON(FAN_MODIFY != FS_MODIFY); @@ -100,15 +130,31 @@ static int fanotify_handle_event(struct fsnotify_group *group, struct fsnotify_e BUILD_BUG_ON(FAN_OPEN != FS_OPEN); BUILD_BUG_ON(FAN_EVENT_ON_CHILD != FS_EVENT_ON_CHILD); BUILD_BUG_ON(FAN_Q_OVERFLOW != FS_Q_OVERFLOW); + BUILD_BUG_ON(FAN_OPEN_PERM != FS_OPEN_PERM); + BUILD_BUG_ON(FAN_ACCESS_PERM != FS_ACCESS_PERM); pr_debug("%s: group=%p event=%p\n", __func__, group, event); - ret = fsnotify_add_notify_event(group, event, NULL, fanotify_merge, (void **)&used_event); + ret = fsnotify_add_notify_event(group, event, NULL, fanotify_merge, + (void **)¬ify_event); /* -EEXIST means this event was merged with another, not that it was an error */ if (ret == -EEXIST) ret = 0; - if (used_event) - fsnotify_put_event(used_event); + if (ret) + goto out; + +#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS + if (event->mask & FAN_ALL_PERM_EVENTS) { + /* if we merged we need to wait on the new event */ + if (notify_event) + event = notify_event; + ret = fanotify_get_response_from_access(group, event); + } +#endif + +out: + if (notify_event) + fsnotify_put_event(notify_event); return ret; } diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c index 84d3e2047de3..09d9bdb62af3 100644 --- a/fs/notify/fanotify/fanotify_user.c +++ b/fs/notify/fanotify/fanotify_user.c @@ -482,6 +482,11 @@ SYSCALL_DEFINE3(fanotify_init, unsigned int, flags, unsigned int, event_f_flags, return PTR_ERR(group); group->priority = priority; +#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS + mutex_init(&group->fanotify_data.access_mutex); + init_waitqueue_head(&group->fanotify_data.access_waitq); + INIT_LIST_HEAD(&group->fanotify_data.access_list); +#endif fd = anon_inode_getfd("[fanotify]", &fanotify_fops, group, f_flags); if (fd < 0) -- cgit v1.2.3-59-g8ed1b