From: Amir Goldstein <amir73il@xxxxxxxxx>
Until now, the high priority classes (FAN_CLASS_*CONTENT), which are
required for permission and pre-content events, were not allowed to
report events with fid info.
This is partly because the event->fd is used as a key for the the
permission response and partly because we needed to chose between
allocating a permission event of fid event struct.
Allow reporting fid info with pre-content class with some restrictions:
1. Only pre-content events are allowed with such groups
2. No event flags are allowed (i.e. FAN_EVENT_ON_CHILD)
The flag FAN_EVENT_ON_CHILD is anyway ignored on sb/mount marks and
on an non-dir inode mark.
On a directory inode mark, FAN_PRE_ACCESS makes no sense without
FAN_EVENT_ON_CHILD, so in this case, this flag is implied.
Add a convenience macro FAN_CLASS_PRE_CONTENT_FID to initialize a
group for pre-content events which reports fid info and dedicate
a new higher priority for those groups.
Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
---
fs/notify/fanotify/fanotify_user.c | 70 +++++++++++++++++++++++-------
include/linux/fsnotify_backend.h | 1 +
include/uapi/linux/fanotify.h | 3 ++
3 files changed, 59 insertions(+), 15 deletions(-)
diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index b192ee068a7a..19d3f2d914fe 100644
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -353,7 +353,7 @@ static int process_access_response(struct fsnotify_group *group,
break;
case FAN_DENY:
/* Custom errno is supported only for pre-content groups */
- if (errno && group->priority != FSNOTIFY_PRIO_PRE_CONTENT)
+ if (errno && group->priority < FSNOTIFY_PRIO_PRE_CONTENT)
return -EINVAL;
/*
@@ -1383,6 +1383,16 @@ static int fanotify_group_init_error_pool(struct fsnotify_group *group)
sizeof(struct fanotify_error_event));
}
+/* Check for forbidden events/flags combinations */
+static bool fanotify_mask_is_valid(__u64 mask)
+{
+ /* Pre-content events do not support event flags */
+ if (mask & FANOTIFY_PRE_CONTENT_EVENTS && mask & FAN_ONDIR)
+ return false;
+
+ return true;
+}
+
static int fanotify_may_update_existing_mark(struct fsnotify_mark *fsn_mark,
__u32 mask, unsigned int fan_flags)
{
@@ -1411,9 +1421,9 @@ static int fanotify_may_update_existing_mark(struct fsnotify_mark *fsn_mark,
fsn_mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY)
return -EEXIST;
- /* For now pre-content events are not generated for directories */
+ /* Check for forbidden event combinations after update */
mask |= fsn_mark->mask;
- if (mask & FANOTIFY_PRE_CONTENT_EVENTS && mask & FAN_ONDIR)
+ if (!fanotify_mask_is_valid(mask))
return -EEXIST;
return 0;
@@ -1564,7 +1574,13 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags)
return -EINVAL;
}
- if (fid_mode && class != FAN_CLASS_NOTIF)
+ /*
+ * Async events support any fid report mode.
+ * Permission events do not support any fid report mode.
+ * Pre-content events support only FAN_REPORT_DFID_NAME_TARGET mode.
+ */
+ if (fid_mode && class != FAN_CLASS_NOTIF &&
+ (class | fid_mode) != FAN_CLASS_PRE_CONTENT_FID)
return -EINVAL;
/*
@@ -1633,7 +1649,12 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags)
group->priority = FSNOTIFY_PRIO_CONTENT;
break;
case FAN_CLASS_PRE_CONTENT:
- group->priority = FSNOTIFY_PRIO_PRE_CONTENT;
+ /*
+ * FAN_CLASS_PRE_CONTENT_FID is exclusively for pre-content
+ * events, so it gets a higher priority.
+ */
+ group->priority = fid_mode ? FSNOTIFY_PRIO_PRE_CONTENT_FID :
+ FSNOTIFY_PRIO_PRE_CONTENT;
break;
default:
fd = -EINVAL;
@@ -1750,6 +1771,9 @@ static int fanotify_events_supported(struct fsnotify_group *group,
(mask & FAN_RENAME) ||
(flags & FAN_MARK_IGNORE);
+ if (!fanotify_mask_is_valid(mask))
+ return -EINVAL;
+
/*
* Filesystems need to opt-into pre-content evnets (a.k.a HSM)
* and they are only supported on regular files and directories.
@@ -1911,13 +1935,27 @@ static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask,
/*
* Permission events are not allowed for FAN_CLASS_NOTIF.
* Pre-content permission events are not allowed for FAN_CLASS_CONTENT.
+ * Only pre-content events are allowed for FAN_CLASS_PRE_CONTENT_FID.
*/
- if (mask & FANOTIFY_PERM_EVENTS &&
- group->priority == FSNOTIFY_PRIO_NORMAL)
- return -EINVAL;
- else if (mask & FANOTIFY_PRE_CONTENT_EVENTS &&
- group->priority == FSNOTIFY_PRIO_CONTENT)
+ fid_mode = FAN_GROUP_FLAG(group, FANOTIFY_FID_BITS);
+ switch (group->priority) {
+ case FSNOTIFY_PRIO_NORMAL:
+ if (mask & FANOTIFY_PERM_EVENTS)
+ return -EINVAL;
+ break;
+ case FSNOTIFY_PRIO_CONTENT:
+ if (mask & FANOTIFY_PRE_CONTENT_EVENTS)
+ return -EINVAL;
+ break;
+ case FSNOTIFY_PRIO_PRE_CONTENT:
+ break;
+ case FSNOTIFY_PRIO_PRE_CONTENT_FID:
+ if (mask & ~FANOTIFY_PRE_CONTENT_EVENTS)
+ return -EINVAL;
+ break;
+ default:
return -EINVAL;
+ }
if (mask & FAN_FS_ERROR &&
mark_type != FAN_MARK_FILESYSTEM)
@@ -1938,7 +1976,6 @@ static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask,
* carry enough information (i.e. path) to be filtered by mount
* point.
*/
- fid_mode = FAN_GROUP_FLAG(group, FANOTIFY_FID_BITS);
if (mask & ~(FANOTIFY_FD_EVENTS|FANOTIFY_MOUNT_EVENTS|FANOTIFY_EVENT_FLAGS) &&
(!fid_mode || mark_type == FAN_MARK_MOUNT))
return -EINVAL;
@@ -1951,10 +1988,6 @@ static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask,
if (mask & FAN_RENAME && !(fid_mode & FAN_REPORT_NAME))
return -EINVAL;
- /* Pre-content events are not currently generated for directories. */
- if (mask & FANOTIFY_PRE_CONTENT_EVENTS && mask & FAN_ONDIR)
- return -EINVAL;
-
if (mark_cmd == FAN_MARK_FLUSH) {
fsnotify_clear_marks_by_group(group, obj_type);
return 0;
@@ -2041,6 +2074,13 @@ static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask,
if ((fid_mode & FAN_REPORT_DIR_FID) &&
(flags & FAN_MARK_ADD) && !ignore)
mask |= FAN_EVENT_ON_CHILD;
+ } else if (fid_mode && (mask & FANOTIFY_PRE_CONTENT_EVENTS)) {
+ /*
+ * Pre-content events on directory inode mask implies that
+ * we are watching access to children.
+ */
+ mask |= FAN_EVENT_ON_CHILD;
+ umask = FAN_EVENT_ON_CHILD;
}
/* create/update an inode mark */
diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h
index d4034ddaf392..832d94d783d9 100644
--- a/include/linux/fsnotify_backend.h
+++ b/include/linux/fsnotify_backend.h
@@ -201,6 +201,7 @@ enum fsnotify_group_prio {
FSNOTIFY_PRIO_NORMAL = 0, /* normal notifiers, no permissions */
FSNOTIFY_PRIO_CONTENT, /* fanotify permission events */
FSNOTIFY_PRIO_PRE_CONTENT, /* fanotify pre-content events */
+ FSNOTIFY_PRIO_PRE_CONTENT_FID, /* fanotify pre-content events with fid */
__FSNOTIFY_PRIO_NUM
};
diff --git a/include/uapi/linux/fanotify.h b/include/uapi/linux/fanotify.h
index e710967c7c26..28074ab3e794 100644
--- a/include/uapi/linux/fanotify.h
+++ b/include/uapi/linux/fanotify.h
@@ -73,6 +73,9 @@
/* Convenience macro - FAN_REPORT_TARGET_FID requires all other FID flags */
#define FAN_REPORT_DFID_NAME_TARGET (FAN_REPORT_DFID_NAME | \
FAN_REPORT_FID | FAN_REPORT_TARGET_FID)
+/* Convenience macro - FAN_CLASS_PRE_CONTENT requires all or no FID flags */
+#define FAN_CLASS_PRE_CONTENT_FID (FAN_CLASS_PRE_CONTENT | \
+ FAN_REPORT_DFID_NAME_TARGET)
/* Deprecated - do not use this in programs and do not add new flags here! */
#define FAN_ALL_INIT_FLAGS (FAN_CLOEXEC | FAN_NONBLOCK | \
--
2.47.1
