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fanotify: add basic support for FAN_REPORT_DIR_FID

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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.

Link: https://lore.kernel.org/r/20200716084230.30611-19-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
This commit is contained in:
Amir Goldstein 2020-07-16 11:42:26 +03:00 committed by Jan Kara
parent 79cb299c7e
commit 83b7a59896
4 changed files with 101 additions and 17 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

34
fs/notify/fanotify/fanotify.c
View File

@ -223,7 +223,7 @@ out:
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 |
@ -243,6 +243,10 @@ 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 && !(event_mask & FS_ISDIR))
return 0;
}
fsnotify_foreach_obj_type(type) {
@ -396,6 +400,28 @@ 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;
}
static struct fanotify_event *fanotify_alloc_path_event(const struct path *path,
gfp_t gfp)
{
@ -491,10 +517,14 @@ static struct fanotify_event *fanotify_alloc_event(struct fsnotify_group *group,
struct fanotify_event *event = NULL;
gfp_t gfp = GFP_KERNEL_ACCOUNT;
struct inode *id = fanotify_fid_inode(mask, data, data_type, dir);
struct inode *dirid = fanotify_dfid_inode(mask, data, data_type, dir);
const struct path *path = fsnotify_data_path(data, data_type);
unsigned int fid_mode = FAN_GROUP_FLAG(group, FANOTIFY_FID_BITS);
bool name_event = false;
if ((fid_mode & FAN_REPORT_DIR_FID) && dirid)
id = dirid;
/*
* For queues with unlimited length lost events are not expected and
* can possibly have security implications. Avoid losing events when
@ -605,7 +635,7 @@ 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;

71
fs/notify/fanotify/fanotify_user.c
View File

@ -216,7 +216,7 @@ 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 = { };
@ -229,7 +229,7 @@ static int copy_info_to_user(__kernel_fsid_t *fsid, struct fanotify_fh *fh,
pr_debug("%s: fh_len=%zu name_len=%zu, info_len=%zu, count=%zu\n",
__func__, fh_len, name_len, info_len, count);
if (!fh_len || (name && !name_len))
if (!fh_len)
return 0;
if (WARN_ON_ONCE(len < sizeof(info) || len > count))
@ -239,8 +239,21 @@ 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 || !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)))
@ -304,8 +317,10 @@ 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_info *info = fanotify_event_info(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);
@ -346,9 +361,10 @@ static ssize_t copy_event_to_user(struct fsnotify_group *group,
/* Event info records order is: dir fid + name, child fid */
if (fanotify_event_dir_fh_len(event)) {
info_type = FAN_EVENT_INFO_TYPE_DFID_NAME;
ret = copy_info_to_user(fanotify_event_fsid(event),
fanotify_info_dir_fh(info),
fanotify_info_name(info),
info_type, fanotify_info_name(info),
info->name_len, buf, count);
if (ret < 0)
return ret;
@ -358,9 +374,33 @@ 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;
@ -861,6 +901,8 @@ 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);
@ -887,10 +929,19 @@ 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);
@ -926,7 +977,7 @@ 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;
@ -1236,7 +1287,7 @@ 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,

2
include/linux/fanotify.h
View File

@ -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 | \

11
include/uapi/linux/fanotify.h
View File

@ -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;