[PATCH v2 7/7] fanotify: clean up CONFIG_FANOTIFY_ACCESS_PERMISSIONS ifdefs

From: Miklos Szeredi
Date: Wed Oct 25 2017 - 04:42:55 EST

The only negative from this patch should be an addition of 32bytes to
'struct fsnotify_group' if CONFIG_FANOTIFY_ACCESS_PERMISSIONS is not
defined.

Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxxxxx>
---
fs/notify/fanotify/fanotify.c | 30 +++------
fs/notify/fanotify/fanotify.h | 8 ++-
fs/notify/fanotify/fanotify_user.c | 123 ++++++++++++++++++-------------------
include/linux/fsnotify_backend.h | 2 -
4 files changed, 72 insertions(+), 91 deletions(-)

diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
index df3f484e458a..63f56b007280 100644
--- a/fs/notify/fanotify/fanotify.c
+++ b/fs/notify/fanotify/fanotify.c
@@ -35,15 +35,13 @@ static int fanotify_merge(struct list_head *list, struct fsnotify_event *event)

pr_debug("%s: list=%p event=%p\n", __func__, list, event);

-#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
/*
* Don't merge a permission event with any other event so that we know
* the event structure we have created in fanotify_handle_event() is the
* one we should check for permission response.
*/
- if (event->mask & FAN_ALL_PERM_EVENTS)
+ if (fanotify_is_perm_event(event->mask))
return 0;
-#endif

list_for_each_entry_reverse(test_event, list, list) {
if (should_merge(test_event, event)) {
@@ -55,7 +53,6 @@ static int fanotify_merge(struct list_head *list, struct fsnotify_event *event)
return 0;
}

-#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
static int fanotify_get_response(struct fsnotify_group *group,
struct fanotify_perm_event_info *event,
struct fsnotify_iter_info *iter_info)
@@ -82,7 +79,6 @@ static int fanotify_get_response(struct fsnotify_group *group,

return ret;
}
-#endif

static bool fanotify_should_send_event(struct fsnotify_mark *inode_mark,
struct fsnotify_mark *vfsmnt_mark,
@@ -141,8 +137,7 @@ struct fanotify_event_info *fanotify_alloc_event(struct inode *inode, u32 mask,
{
struct fanotify_event_info *event;

-#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
- if (mask & FAN_ALL_PERM_EVENTS) {
+ if (fanotify_is_perm_event(mask)) {
struct fanotify_perm_event_info *pevent;

pevent = kmem_cache_alloc(fanotify_perm_event_cachep,
@@ -153,7 +148,6 @@ struct fanotify_event_info *fanotify_alloc_event(struct inode *inode, u32 mask,
pevent->response = 0;
goto init;
}
-#endif
event = kmem_cache_alloc(fanotify_event_cachep, GFP_KERNEL);
if (!event)
return NULL;
@@ -200,8 +194,7 @@ static int fanotify_handle_event(struct fsnotify_group *group,
pr_debug("%s: group=%p inode=%p mask=%x\n", __func__, group, inode,
mask);

-#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
- if (mask & FAN_ALL_PERM_EVENTS) {
+ if (fanotify_is_perm_event(mask)) {
/*
* fsnotify_prepare_user_wait() fails if we race with mark
* deletion. Just let the operation pass in that case.
@@ -209,7 +202,6 @@ static int fanotify_handle_event(struct fsnotify_group *group,
if (!fsnotify_prepare_user_wait(iter_info))
return 0;
}
-#endif

event = fanotify_alloc_event(inode, mask, data);
ret = -ENOMEM;
@@ -225,21 +217,15 @@ static int fanotify_handle_event(struct fsnotify_group *group,
fsnotify_destroy_event(group, fsn_event);

ret = 0;
- goto finish;
- }
-
-#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
- if (mask & FAN_ALL_PERM_EVENTS) {
+ } else if (fanotify_is_perm_event(mask)) {
ret = fanotify_get_response(group, FANOTIFY_PE(fsn_event),
iter_info);
fsnotify_destroy_event(group, fsn_event);
}
finish:
- if (mask & FAN_ALL_PERM_EVENTS)
+ if (fanotify_is_perm_event(mask))
fsnotify_finish_user_wait(iter_info);
-#else
-finish:
-#endif
+
return ret;
}

@@ -259,13 +245,11 @@ static void fanotify_free_event(struct fsnotify_event *fsn_event)
event = FANOTIFY_E(fsn_event);
path_put(&event->path);
put_pid(event->tgid);
-#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
- if (fsn_event->mask & FAN_ALL_PERM_EVENTS) {
+ if (fanotify_is_perm_event(fsn_event->mask)) {
kmem_cache_free(fanotify_perm_event_cachep,
FANOTIFY_PE(fsn_event));
return;
}
-#endif
kmem_cache_free(fanotify_event_cachep, event);
}

diff --git a/fs/notify/fanotify/fanotify.h b/fs/notify/fanotify/fanotify.h
index 4eb6f5efa282..dc219cf07a6a 100644
--- a/fs/notify/fanotify/fanotify.h
+++ b/fs/notify/fanotify/fanotify.h
@@ -21,7 +21,6 @@ struct fanotify_event_info {
struct pid *tgid;
};

-#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
/*
* Structure for permission fanotify events. It gets allocated and freed in
* fanotify_handle_event() since we wait there for user response. When the
@@ -40,7 +39,12 @@ FANOTIFY_PE(struct fsnotify_event *fse)
{
return container_of(fse, struct fanotify_perm_event_info, fae.fse);
}
-#endif
+
+static inline bool fanotify_is_perm_event(u32 mask)
+{
+ return IS_ENABLED(CONFIG_FANOTIFY_ACCESS_PERMISSIONS) &&
+ mask & FAN_ALL_PERM_EVENTS;
+}

static inline struct fanotify_event_info *FANOTIFY_E(struct fsnotify_event *fse)
{
diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index 907a481ac781..44fd12aa17ff 100644
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -142,7 +142,6 @@ static int fill_event_metadata(struct fsnotify_group *group,
return ret;
}

-#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
static struct fanotify_perm_event_info *dequeue_event(
struct fsnotify_group *group, int fd)
{
@@ -199,7 +198,6 @@ static int process_access_response(struct fsnotify_group *group,

return 0;
}
-#endif

static ssize_t copy_event_to_user(struct fsnotify_group *group,
struct fsnotify_event *event,
@@ -221,10 +219,8 @@ static ssize_t copy_event_to_user(struct fsnotify_group *group,
fanotify_event_metadata.event_len))
goto out_close_fd;

-#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
- if (event->mask & FAN_ALL_PERM_EVENTS)
+ if (fanotify_is_perm_event(event->mask))
FANOTIFY_PE(event)->fd = fd;
-#endif

if (fd != FAN_NOFD)
fd_install(fd, f);
@@ -309,10 +305,9 @@ static ssize_t fanotify_read(struct file *file, char __user *buf,
* Permission events get queued to wait for response. Other
* events can be destroyed now.
*/
- if (!(kevent->mask & FAN_ALL_PERM_EVENTS)) {
+ if (!fanotify_is_perm_event(kevent->mask)) {
fsnotify_destroy_event(group, kevent);
} else {
-#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
if (ret <= 0) {
FANOTIFY_PE(kevent)->response = FAN_DENY;
wake_up(&group->fanotify_data.access_waitq);
@@ -322,7 +317,6 @@ static ssize_t fanotify_read(struct file *file, char __user *buf,
&group->fanotify_data.access_list);
spin_unlock(&group->notification_lock);
}
-#endif
}
if (ret < 0)
break;
@@ -338,11 +332,14 @@ static ssize_t fanotify_read(struct file *file, char __user *buf,

static ssize_t fanotify_write(struct file *file, const char __user *buf, size_t count, loff_t *pos)
{
-#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
struct fanotify_response response = { .fd = -1, .response = -1 };
struct fsnotify_group *group;
int ret;

+ if (!IS_ENABLED(CONFIG_FANOTIFY_ACCESS_PERMISSIONS))
+ return -EINVAL;
+
+
group = file->private_data;

if (count > sizeof(response))
@@ -358,59 +355,57 @@ static ssize_t fanotify_write(struct file *file, const char __user *buf, size_t
count = ret;

return count;
-#else
- return -EINVAL;
-#endif
}

static int fanotify_release(struct inode *ignored, struct file *file)
{
struct fsnotify_group *group = file->private_data;

-#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
- struct fanotify_perm_event_info *event, *next;
- struct fsnotify_event *fsn_event;
+ if (IS_ENABLED(CONFIG_FANOTIFY_ACCESS_PERMISSIONS)) {
+ struct fanotify_perm_event_info *event, *next;
+ struct fsnotify_event *fsn_event;

- /*
- * Stop new events from arriving in the notification queue. since
- * userspace cannot use fanotify fd anymore, no event can enter or
- * leave access_list by now either.
- */
- fsnotify_group_stop_queueing(group);
+ /*
+ * Stop new events from arriving in the notification
+ * queue. since userspace cannot use fanotify fd anymore, no
+ * event can enter or leave access_list by now either.
+ */
+ fsnotify_group_stop_queueing(group);

- /*
- * Process all permission events on access_list and notification queue
- * and simulate reply from userspace.
- */
- spin_lock(&group->notification_lock);
- list_for_each_entry_safe(event, next, &group->fanotify_data.access_list,
- fae.fse.list) {
- pr_debug("%s: found group=%p event=%p\n", __func__, group,
- event);
+ /*
+ * Process all permission events on access_list and notification
+ * queue and simulate reply from userspace.
+ */
+ spin_lock(&group->notification_lock);
+ list_for_each_entry_safe(event, next,
+ &group->fanotify_data.access_list,
+ fae.fse.list) {
+ pr_debug("%s: found group=%p event=%p\n", __func__,
+ group, event);
+
+ list_del_init(&event->fae.fse.list);
+ event->response = FAN_ALLOW;
+ }

- list_del_init(&event->fae.fse.list);
- event->response = FAN_ALLOW;
- }
+ /*
+ * Destroy all non-permission events. For permission events just
+ * dequeue them and set the response. They will be freed once
+ * the response is consumed and fanotify_get_response() returns.
+ */
+ while (!fsnotify_notify_queue_is_empty(group)) {
+ fsn_event = fsnotify_remove_first_event(group);
+ if (!(fsn_event->mask & FAN_ALL_PERM_EVENTS)) {
+ spin_unlock(&group->notification_lock);
+ fsnotify_destroy_event(group, fsn_event);
+ spin_lock(&group->notification_lock);
+ } else
+ FANOTIFY_PE(fsn_event)->response = FAN_ALLOW;
+ }
+ spin_unlock(&group->notification_lock);

- /*
- * Destroy all non-permission events. For permission events just
- * dequeue them and set the response. They will be freed once the
- * response is consumed and fanotify_get_response() returns.
- */
- while (!fsnotify_notify_queue_is_empty(group)) {
- fsn_event = fsnotify_remove_first_event(group);
- if (!(fsn_event->mask & FAN_ALL_PERM_EVENTS)) {
- spin_unlock(&group->notification_lock);
- fsnotify_destroy_event(group, fsn_event);
- spin_lock(&group->notification_lock);
- } else
- FANOTIFY_PE(fsn_event)->response = FAN_ALLOW;
+ /* Response for all permission events it set, wakeup waiters */
+ wake_up(&group->fanotify_data.access_waitq);
}
- spin_unlock(&group->notification_lock);
-
- /* Response for all permission events it set, wakeup waiters */
- wake_up(&group->fanotify_data.access_waitq);
-#endif

/* matches the fanotify_init->fsnotify_alloc_group */
fsnotify_destroy_group(group);
@@ -768,10 +763,10 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags)
if (force_o_largefile())
event_f_flags |= O_LARGEFILE;
group->fanotify_data.f_flags = event_f_flags;
-#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
- init_waitqueue_head(&group->fanotify_data.access_waitq);
- INIT_LIST_HEAD(&group->fanotify_data.access_list);
-#endif
+ if (IS_ENABLED(CONFIG_FANOTIFY_ACCESS_PERMISSIONS)) {
+ init_waitqueue_head(&group->fanotify_data.access_waitq);
+ INIT_LIST_HEAD(&group->fanotify_data.access_list);
+ }
switch (flags & FAN_ALL_CLASS_BITS) {
case FAN_CLASS_NOTIF:
group->priority = FS_PRIO_0;
@@ -825,6 +820,7 @@ SYSCALL_DEFINE5(fanotify_mark, int, fanotify_fd, unsigned int, flags,
struct fsnotify_group *group;
struct fd f;
struct path path;
+ u32 valid_mask = FAN_ALL_EVENTS | FAN_EVENT_ON_CHILD;
int ret;

pr_debug("%s: fanotify_fd=%d flags=%x dfd=%d pathname=%p mask=%llx\n",
@@ -855,11 +851,10 @@ SYSCALL_DEFINE5(fanotify_mark, int, fanotify_fd, unsigned int, flags,
mask &= ~FAN_ONDIR;
}

-#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
- if (mask & ~(FAN_ALL_EVENTS | FAN_ALL_PERM_EVENTS | FAN_EVENT_ON_CHILD))
-#else
- if (mask & ~(FAN_ALL_EVENTS | FAN_EVENT_ON_CHILD))
-#endif
+ if (IS_ENABLED(CONFIG_FANOTIFY_ACCESS_PERMISSIONS))
+ valid_mask |= FAN_ALL_PERM_EVENTS;
+
+ if (mask & ~valid_mask)
return -EINVAL;

f = fdget(fanotify_fd);
@@ -949,10 +944,10 @@ static int __init fanotify_user_setup(void)
{
fanotify_mark_cache = KMEM_CACHE(fsnotify_mark, SLAB_PANIC);
fanotify_event_cachep = KMEM_CACHE(fanotify_event_info, SLAB_PANIC);
-#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
- fanotify_perm_event_cachep = KMEM_CACHE(fanotify_perm_event_info,
- SLAB_PANIC);
-#endif
+ if (IS_ENABLED(CONFIG_FANOTIFY_ACCESS_PERMISSIONS)) {
+ fanotify_perm_event_cachep =
+ KMEM_CACHE(fanotify_perm_event_info, SLAB_PANIC);
+ }

return 0;
}
diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h
index c6c69318752b..eaea494683ab 100644
--- a/include/linux/fsnotify_backend.h
+++ b/include/linux/fsnotify_backend.h
@@ -182,11 +182,9 @@ struct fsnotify_group {
#endif
#ifdef CONFIG_FANOTIFY
struct fanotify_group_private_data {
-#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
/* allows a group to block waiting for a userspace response */
struct list_head access_list;
wait_queue_head_t access_waitq;
-#endif /* CONFIG_FANOTIFY_ACCESS_PERMISSIONS */
int f_flags;
unsigned int max_marks;
struct user_struct *user;
--
2.5.5