For now, the flag is mutually exclusive with FAN_REPORT_FID.
Events include a single info record of type FAN_EVENT_INFO_TYPE_DFID
with a directory file handle.
For now, events are only reported for:
- Directory modification events
- Events on children of a watching directory
- Events on directory objects
Soon, we will add support for reporting the parent directory fid
for events on non-directories with filesystem/mount mark and
support for reporting both parent directory fid and child fid.
Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
---
fs/notify/fanotify/fanotify.c | 33 +++++++++++++-
fs/notify/fanotify/fanotify_user.c | 69 ++++++++++++++++++++++++++----
include/linux/fanotify.h | 2 +-
include/uapi/linux/fanotify.h | 11 +++--
4 files changed, 99 insertions(+), 16 deletions(-)
diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
index 7f40b8f57934..23fb1bfb6945 100644
--- a/fs/notify/fanotify/fanotify.c
+++ b/fs/notify/fanotify/fanotify.c
@@ -206,7 +206,7 @@ static int fanotify_get_response(struct fsnotify_group *group,
static u32 fanotify_group_event_mask(struct fsnotify_group *group,
struct fsnotify_iter_info *iter_info,
u32 event_mask, const void *data,
- int data_type)
+ int data_type, struct inode *dir)
{
__u32 marks_mask = 0, marks_ignored_mask = 0;
__u32 test_mask, user_mask = FANOTIFY_OUTGOING_EVENTS |
@@ -226,6 +226,10 @@ static u32 fanotify_group_event_mask(struct fsnotify_group *group,
/* Path type events are only relevant for files and dirs */
if (!d_is_reg(path->dentry) && !d_can_lookup(path->dentry))
return 0;
+ } else if (!(fid_mode & FAN_REPORT_FID)) {
+ /* Do we have a directory inode to report? */
+ if (!dir)
+ return 0;
}
fsnotify_foreach_obj_type(type) {
@@ -375,6 +379,28 @@ static struct inode *fanotify_fid_inode(u32 event_mask, const void *data,
return fsnotify_data_inode(data, data_type);
}
+/*
+ * The inode to use as identifier when reporting dir fid depends on the event.
+ * Report the modified directory inode on dirent modification events.
+ * Report the "victim" inode if "victim" is a directory.
+ * Report the parent inode if "victim" is not a directory and event is
+ * reported to parent.
+ * Otherwise, do not report dir fid.
+ */
+static struct inode *fanotify_dfid_inode(u32 event_mask, const void *data,
+ int data_type, struct inode *dir)
+{
+ struct inode *inode = fsnotify_data_inode(data, data_type);
+
+ if (event_mask & ALL_FSNOTIFY_DIRENT_EVENTS)
+ return dir;
+
+ if (S_ISDIR(inode->i_mode))
+ return inode;
+
+ return dir;
+}
+
struct fanotify_event *fanotify_alloc_path_event(const struct path *path,
gfp_t gfp)
{
@@ -470,6 +496,9 @@ static struct fanotify_event *fanotify_alloc_event(struct fsnotify_group *group,
unsigned int fid_mode = FAN_GROUP_FLAG(group, FANOTIFY_FID_BITS);
bool name_event = false;
+ if ((fid_mode & FAN_REPORT_DIR_FID) && dir)
+ id = fanotify_dfid_inode(mask, data, data_type, dir);
+
/*
* For queues with unlimited length lost events are not expected and
* can possibly have security implications. Avoid losing events when
@@ -580,7 +609,7 @@ static int fanotify_handle_event(struct fsnotify_group *group, u32 mask,
BUILD_BUG_ON(HWEIGHT32(ALL_FANOTIFY_EVENT_BITS) != 19);
mask = fanotify_group_event_mask(group, iter_info, mask, data,
- data_type);
+ data_type, dir);
if (!mask)
return 0;
diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index af8268b44c68..fe2c25e26753 100644
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -215,7 +215,7 @@ static int process_access_response(struct fsnotify_group *group,
}
static int copy_info_to_user(__kernel_fsid_t *fsid, struct fanotify_fh *fh,
- const char *name, size_t name_len,
+ int info_type, const char *name, size_t name_len,
char __user *buf, size_t count)
{
struct fanotify_event_info_fid info = { };
@@ -238,8 +238,21 @@ static int copy_info_to_user(__kernel_fsid_t *fsid, struct fanotify_fh *fh,
* Copy event info fid header followed by variable sized file handle
* and optionally followed by variable sized filename.
*/
- info.hdr.info_type = name_len ? FAN_EVENT_INFO_TYPE_DFID_NAME :
- FAN_EVENT_INFO_TYPE_FID;
+ switch (info_type) {
+ case FAN_EVENT_INFO_TYPE_FID:
+ case FAN_EVENT_INFO_TYPE_DFID:
+ if (WARN_ON_ONCE(name_len))
+ return -EFAULT;
+ break;
+ case FAN_EVENT_INFO_TYPE_DFID_NAME:
+ if (WARN_ON_ONCE(!name_len))
+ return -EFAULT;
+ break;
+ default:
+ return -EFAULT;
+ }
+
+ info.hdr.info_type = info_type;
info.hdr.len = len;
info.fsid = *fsid;
if (copy_to_user(buf, &info, sizeof(info)))
@@ -303,8 +316,10 @@ static ssize_t copy_event_to_user(struct fsnotify_group *group,
struct fanotify_event_metadata metadata;
struct path *path = fanotify_event_path(event);
struct fanotify_fh *dfh = fanotify_event_dir_fh(event);
+ unsigned int fid_mode = FAN_GROUP_FLAG(group, FANOTIFY_FID_BITS);
struct file *f = NULL;
int ret, fd = FAN_NOFD;
+ int info_type = 0;
pr_debug("%s: group=%p event=%p\n", __func__, group, event);
@@ -345,8 +360,9 @@ static ssize_t copy_event_to_user(struct fsnotify_group *group,
/* Event info records order is: dir fid + name, child fid */
if (dfh) {
+ info_type = FAN_EVENT_INFO_TYPE_DFID_NAME;
ret = copy_info_to_user(fanotify_event_fsid(event), dfh,
- fanotify_fh_name(dfh),
+ info_type, fanotify_fh_name(dfh),
dfh->name_len, buf, count);
if (ret < 0)
return ret;
@@ -356,9 +372,33 @@ static ssize_t copy_event_to_user(struct fsnotify_group *group,
}
if (fanotify_event_object_fh_len(event)) {
+ if (fid_mode == FAN_REPORT_FID || info_type) {
+ /*
+ * With only group flag FAN_REPORT_FID only type FID is
+ * reported. Second info record type is always FID.
+ */
+ info_type = FAN_EVENT_INFO_TYPE_FID;
+ } else if ((event->mask & ALL_FSNOTIFY_DIRENT_EVENTS) ||
+ (event->mask & FAN_ONDIR)) {
+ /*
+ * With group flag FAN_REPORT_DIR_FID, a single info
+ * record has type DFID for directory entry modification
+ * event and for event on a directory.
+ */
+ info_type = FAN_EVENT_INFO_TYPE_DFID;
+ } else {
+ /*
+ * With group flags FAN_REPORT_DIR_FID|FAN_REPORT_FID,
+ * a single info record has type FID for event on a
+ * non-directory, when there is no directory to report.
+ * For example, on FAN_DELETE_SELF event.
+ */
+ info_type = FAN_EVENT_INFO_TYPE_FID;
+ }
+
ret = copy_info_to_user(fanotify_event_fsid(event),
fanotify_event_object_fh(event),
- NULL, 0, buf, count);
+ info_type, NULL, 0, buf, count);
if (ret < 0)
return ret;
@@ -854,6 +894,8 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags)
struct fsnotify_group *group;
int f_flags, fd;
struct user_struct *user;
+ unsigned int fid_mode = flags & FANOTIFY_FID_BITS;
+ unsigned int class = flags & FANOTIFY_CLASS_BITS;
pr_debug("%s: flags=%x event_f_flags=%x\n",
__func__, flags, event_f_flags);
@@ -880,10 +922,19 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags)
return -EINVAL;
}
- if ((flags & FANOTIFY_FID_BITS) &&
- (flags & FANOTIFY_CLASS_BITS) != FAN_CLASS_NOTIF)
+ if (fid_mode && class != FAN_CLASS_NOTIF)
return -EINVAL;
+ /* Reporting either object fid or dir fid */
+ switch (fid_mode) {
+ case 0:
+ case FAN_REPORT_FID:
+ case FAN_REPORT_DIR_FID:
+ break;
+ default:
+ return -EINVAL;
+ }
+
user = get_current_user();
if (atomic_read(&user->fanotify_listeners) > FANOTIFY_DEFAULT_MAX_LISTENERS) {
free_uid(user);
@@ -919,7 +970,7 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags)
group->fanotify_data.f_flags = event_f_flags;
init_waitqueue_head(&group->fanotify_data.access_waitq);
INIT_LIST_HEAD(&group->fanotify_data.access_list);
- switch (flags & FANOTIFY_CLASS_BITS) {
+ switch (class) {
case FAN_CLASS_NOTIF:
group->priority = FS_PRIO_0;
break;
@@ -1229,7 +1280,7 @@ COMPAT_SYSCALL_DEFINE6(fanotify_mark,
*/
static int __init fanotify_user_setup(void)
{
- BUILD_BUG_ON(HWEIGHT32(FANOTIFY_INIT_FLAGS) != 8);
+ BUILD_BUG_ON(HWEIGHT32(FANOTIFY_INIT_FLAGS) != 9);
BUILD_BUG_ON(HWEIGHT32(FANOTIFY_MARK_FLAGS) != 9);
fanotify_mark_cache = KMEM_CACHE(fsnotify_mark,
diff --git a/include/linux/fanotify.h b/include/linux/fanotify.h
index bbbee11d2521..4ddac97b2bf7 100644
--- a/include/linux/fanotify.h
+++ b/include/linux/fanotify.h
@@ -18,7 +18,7 @@
#define FANOTIFY_CLASS_BITS (FAN_CLASS_NOTIF | FAN_CLASS_CONTENT | \
FAN_CLASS_PRE_CONTENT)
-#define FANOTIFY_FID_BITS (FAN_REPORT_FID)
+#define FANOTIFY_FID_BITS (FAN_REPORT_FID | FAN_REPORT_DIR_FID)
#define FANOTIFY_INIT_FLAGS (FANOTIFY_CLASS_BITS | FANOTIFY_FID_BITS | \
FAN_REPORT_TID | \
diff --git a/include/uapi/linux/fanotify.h b/include/uapi/linux/fanotify.h
index 7f2f17eacbf9..21afebf77fd7 100644
--- a/include/uapi/linux/fanotify.h
+++ b/include/uapi/linux/fanotify.h
@@ -53,6 +53,7 @@
/* Flags to determine fanotify event format */
#define FAN_REPORT_TID 0x00000100 /* event->pid is thread id */
#define FAN_REPORT_FID 0x00000200 /* Report unique file id */
+#define FAN_REPORT_DIR_FID 0x00000400 /* Report unique directory id */
/* Deprecated - do not use this in programs and do not add new flags here! */
#define FAN_ALL_INIT_FLAGS (FAN_CLOEXEC | FAN_NONBLOCK | \
@@ -117,6 +118,7 @@ struct fanotify_event_metadata {
#define FAN_EVENT_INFO_TYPE_FID 1
#define FAN_EVENT_INFO_TYPE_DFID_NAME 2
+#define FAN_EVENT_INFO_TYPE_DFID 3
/* Variable length info record following event metadata */
struct fanotify_event_info_header {
@@ -126,10 +128,11 @@ struct fanotify_event_info_header {
};
/*
- * Unique file identifier info record. This is used both for
- * FAN_EVENT_INFO_TYPE_FID records and for FAN_EVENT_INFO_TYPE_DFID_NAME
- * records. For FAN_EVENT_INFO_TYPE_DFID_NAME there is additionally a null
- * terminated name immediately after the file handle.
+ * Unique file identifier info record.
+ * This structure is used for records of types FAN_EVENT_INFO_TYPE_FID,
+ * FAN_EVENT_INFO_TYPE_DFID and FAN_EVENT_INFO_TYPE_DFID_NAME.
+ * For FAN_EVENT_INFO_TYPE_DFID_NAME there is additionally a null terminated
+ * name immediately after the file handle.
*/
struct fanotify_event_info_fid {
struct fanotify_event_info_header hdr;
--
2.17.1
