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fanotify: add basic support for FAN_REPORT_DIR_FID
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>
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79cb299c7e
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83b7a59896
@ -223,7 +223,7 @@ out:
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static u32 fanotify_group_event_mask(struct fsnotify_group *group,
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struct fsnotify_iter_info *iter_info,
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u32 event_mask, const void *data,
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int data_type)
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int data_type, struct inode *dir)
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{
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__u32 marks_mask = 0, marks_ignored_mask = 0;
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__u32 test_mask, user_mask = FANOTIFY_OUTGOING_EVENTS |
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@ -243,6 +243,10 @@ static u32 fanotify_group_event_mask(struct fsnotify_group *group,
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/* Path type events are only relevant for files and dirs */
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if (!d_is_reg(path->dentry) && !d_can_lookup(path->dentry))
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return 0;
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} else if (!(fid_mode & FAN_REPORT_FID)) {
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/* Do we have a directory inode to report? */
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if (!dir && !(event_mask & FS_ISDIR))
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return 0;
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}
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fsnotify_foreach_obj_type(type) {
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@ -396,6 +400,28 @@ static struct inode *fanotify_fid_inode(u32 event_mask, const void *data,
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return fsnotify_data_inode(data, data_type);
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}
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/*
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* The inode to use as identifier when reporting dir fid depends on the event.
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* Report the modified directory inode on dirent modification events.
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* Report the "victim" inode if "victim" is a directory.
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* Report the parent inode if "victim" is not a directory and event is
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* reported to parent.
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* Otherwise, do not report dir fid.
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*/
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static struct inode *fanotify_dfid_inode(u32 event_mask, const void *data,
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int data_type, struct inode *dir)
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{
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struct inode *inode = fsnotify_data_inode(data, data_type);
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if (event_mask & ALL_FSNOTIFY_DIRENT_EVENTS)
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return dir;
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if (S_ISDIR(inode->i_mode))
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return inode;
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return dir;
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}
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static struct fanotify_event *fanotify_alloc_path_event(const struct path *path,
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gfp_t gfp)
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{
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@ -491,10 +517,14 @@ static struct fanotify_event *fanotify_alloc_event(struct fsnotify_group *group,
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struct fanotify_event *event = NULL;
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gfp_t gfp = GFP_KERNEL_ACCOUNT;
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struct inode *id = fanotify_fid_inode(mask, data, data_type, dir);
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struct inode *dirid = fanotify_dfid_inode(mask, data, data_type, dir);
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const struct path *path = fsnotify_data_path(data, data_type);
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unsigned int fid_mode = FAN_GROUP_FLAG(group, FANOTIFY_FID_BITS);
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bool name_event = false;
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if ((fid_mode & FAN_REPORT_DIR_FID) && dirid)
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id = dirid;
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/*
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* For queues with unlimited length lost events are not expected and
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* can possibly have security implications. Avoid losing events when
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@ -605,7 +635,7 @@ static int fanotify_handle_event(struct fsnotify_group *group, u32 mask,
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BUILD_BUG_ON(HWEIGHT32(ALL_FANOTIFY_EVENT_BITS) != 19);
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mask = fanotify_group_event_mask(group, iter_info, mask, data,
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data_type);
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data_type, dir);
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if (!mask)
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return 0;
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@ -216,7 +216,7 @@ static int process_access_response(struct fsnotify_group *group,
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}
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static int copy_info_to_user(__kernel_fsid_t *fsid, struct fanotify_fh *fh,
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const char *name, size_t name_len,
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int info_type, const char *name, size_t name_len,
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char __user *buf, size_t count)
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{
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struct fanotify_event_info_fid info = { };
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@ -229,7 +229,7 @@ static int copy_info_to_user(__kernel_fsid_t *fsid, struct fanotify_fh *fh,
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pr_debug("%s: fh_len=%zu name_len=%zu, info_len=%zu, count=%zu\n",
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__func__, fh_len, name_len, info_len, count);
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if (!fh_len || (name && !name_len))
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if (!fh_len)
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return 0;
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if (WARN_ON_ONCE(len < sizeof(info) || len > count))
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@ -239,8 +239,21 @@ static int copy_info_to_user(__kernel_fsid_t *fsid, struct fanotify_fh *fh,
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* Copy event info fid header followed by variable sized file handle
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* and optionally followed by variable sized filename.
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*/
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info.hdr.info_type = name_len ? FAN_EVENT_INFO_TYPE_DFID_NAME :
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FAN_EVENT_INFO_TYPE_FID;
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switch (info_type) {
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case FAN_EVENT_INFO_TYPE_FID:
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case FAN_EVENT_INFO_TYPE_DFID:
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if (WARN_ON_ONCE(name_len))
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return -EFAULT;
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break;
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case FAN_EVENT_INFO_TYPE_DFID_NAME:
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if (WARN_ON_ONCE(!name || !name_len))
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return -EFAULT;
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break;
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default:
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return -EFAULT;
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}
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info.hdr.info_type = info_type;
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info.hdr.len = len;
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info.fsid = *fsid;
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if (copy_to_user(buf, &info, sizeof(info)))
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@ -304,8 +317,10 @@ static ssize_t copy_event_to_user(struct fsnotify_group *group,
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struct fanotify_event_metadata metadata;
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struct path *path = fanotify_event_path(event);
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struct fanotify_info *info = fanotify_event_info(event);
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unsigned int fid_mode = FAN_GROUP_FLAG(group, FANOTIFY_FID_BITS);
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struct file *f = NULL;
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int ret, fd = FAN_NOFD;
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int info_type = 0;
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pr_debug("%s: group=%p event=%p\n", __func__, group, event);
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@ -346,9 +361,10 @@ static ssize_t copy_event_to_user(struct fsnotify_group *group,
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/* Event info records order is: dir fid + name, child fid */
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if (fanotify_event_dir_fh_len(event)) {
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info_type = FAN_EVENT_INFO_TYPE_DFID_NAME;
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ret = copy_info_to_user(fanotify_event_fsid(event),
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fanotify_info_dir_fh(info),
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fanotify_info_name(info),
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info_type, fanotify_info_name(info),
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info->name_len, buf, count);
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if (ret < 0)
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return ret;
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@ -358,9 +374,33 @@ static ssize_t copy_event_to_user(struct fsnotify_group *group,
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}
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if (fanotify_event_object_fh_len(event)) {
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if (fid_mode == FAN_REPORT_FID || info_type) {
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/*
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* With only group flag FAN_REPORT_FID only type FID is
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* reported. Second info record type is always FID.
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*/
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info_type = FAN_EVENT_INFO_TYPE_FID;
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} else if ((event->mask & ALL_FSNOTIFY_DIRENT_EVENTS) ||
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(event->mask & FAN_ONDIR)) {
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/*
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* With group flag FAN_REPORT_DIR_FID, a single info
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* record has type DFID for directory entry modification
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* event and for event on a directory.
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*/
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info_type = FAN_EVENT_INFO_TYPE_DFID;
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} else {
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/*
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* With group flags FAN_REPORT_DIR_FID|FAN_REPORT_FID,
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* a single info record has type FID for event on a
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* non-directory, when there is no directory to report.
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* For example, on FAN_DELETE_SELF event.
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*/
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info_type = FAN_EVENT_INFO_TYPE_FID;
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}
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ret = copy_info_to_user(fanotify_event_fsid(event),
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fanotify_event_object_fh(event),
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NULL, 0, buf, count);
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info_type, NULL, 0, buf, count);
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if (ret < 0)
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return ret;
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@ -861,6 +901,8 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags)
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struct fsnotify_group *group;
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int f_flags, fd;
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struct user_struct *user;
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unsigned int fid_mode = flags & FANOTIFY_FID_BITS;
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unsigned int class = flags & FANOTIFY_CLASS_BITS;
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pr_debug("%s: flags=%x event_f_flags=%x\n",
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__func__, flags, event_f_flags);
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@ -887,10 +929,19 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags)
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return -EINVAL;
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}
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if ((flags & FANOTIFY_FID_BITS) &&
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(flags & FANOTIFY_CLASS_BITS) != FAN_CLASS_NOTIF)
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if (fid_mode && class != FAN_CLASS_NOTIF)
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return -EINVAL;
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/* Reporting either object fid or dir fid */
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switch (fid_mode) {
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case 0:
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case FAN_REPORT_FID:
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case FAN_REPORT_DIR_FID:
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break;
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default:
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return -EINVAL;
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}
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user = get_current_user();
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if (atomic_read(&user->fanotify_listeners) > FANOTIFY_DEFAULT_MAX_LISTENERS) {
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free_uid(user);
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@ -926,7 +977,7 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags)
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group->fanotify_data.f_flags = event_f_flags;
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init_waitqueue_head(&group->fanotify_data.access_waitq);
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INIT_LIST_HEAD(&group->fanotify_data.access_list);
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switch (flags & FANOTIFY_CLASS_BITS) {
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switch (class) {
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case FAN_CLASS_NOTIF:
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group->priority = FS_PRIO_0;
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break;
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@ -1236,7 +1287,7 @@ COMPAT_SYSCALL_DEFINE6(fanotify_mark,
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*/
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static int __init fanotify_user_setup(void)
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{
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BUILD_BUG_ON(HWEIGHT32(FANOTIFY_INIT_FLAGS) != 8);
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BUILD_BUG_ON(HWEIGHT32(FANOTIFY_INIT_FLAGS) != 9);
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BUILD_BUG_ON(HWEIGHT32(FANOTIFY_MARK_FLAGS) != 9);
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fanotify_mark_cache = KMEM_CACHE(fsnotify_mark,
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@ -18,7 +18,7 @@
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#define FANOTIFY_CLASS_BITS (FAN_CLASS_NOTIF | FAN_CLASS_CONTENT | \
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FAN_CLASS_PRE_CONTENT)
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#define FANOTIFY_FID_BITS (FAN_REPORT_FID)
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#define FANOTIFY_FID_BITS (FAN_REPORT_FID | FAN_REPORT_DIR_FID)
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#define FANOTIFY_INIT_FLAGS (FANOTIFY_CLASS_BITS | FANOTIFY_FID_BITS | \
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FAN_REPORT_TID | \
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@ -53,6 +53,7 @@
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/* Flags to determine fanotify event format */
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#define FAN_REPORT_TID 0x00000100 /* event->pid is thread id */
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#define FAN_REPORT_FID 0x00000200 /* Report unique file id */
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#define FAN_REPORT_DIR_FID 0x00000400 /* Report unique directory id */
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/* Deprecated - do not use this in programs and do not add new flags here! */
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#define FAN_ALL_INIT_FLAGS (FAN_CLOEXEC | FAN_NONBLOCK | \
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@ -117,6 +118,7 @@ struct fanotify_event_metadata {
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#define FAN_EVENT_INFO_TYPE_FID 1
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#define FAN_EVENT_INFO_TYPE_DFID_NAME 2
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#define FAN_EVENT_INFO_TYPE_DFID 3
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/* Variable length info record following event metadata */
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struct fanotify_event_info_header {
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@ -126,10 +128,11 @@ struct fanotify_event_info_header {
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};
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/*
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* Unique file identifier info record. This is used both for
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* FAN_EVENT_INFO_TYPE_FID records and for FAN_EVENT_INFO_TYPE_DFID_NAME
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* records. For FAN_EVENT_INFO_TYPE_DFID_NAME there is additionally a null
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* terminated name immediately after the file handle.
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* Unique file identifier info record.
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* This structure is used for records of types FAN_EVENT_INFO_TYPE_FID,
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* FAN_EVENT_INFO_TYPE_DFID and FAN_EVENT_INFO_TYPE_DFID_NAME.
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* For FAN_EVENT_INFO_TYPE_DFID_NAME there is additionally a null terminated
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* name immediately after the file handle.
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*/
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struct fanotify_event_info_fid {
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struct fanotify_event_info_header hdr;
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