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fanotify: introduce a generic info record copying helper
The copy_info_records_to_user() helper allows for the separation of info record copying routines/conditionals from copy_event_to_user(), which reduces the overall clutter within this function. This becomes especially true as we start introducing additional info records in the future i.e. struct fanotify_event_info_pidfd. On success, this helper returns the total amount of bytes that have been copied into the user supplied buffer and on error, a negative value is returned to the caller. The newly defined macro FANOTIFY_INFO_MODES can be used to obtain info record types that have been enabled for a specific notification group. This macro becomes useful in the subsequent patch when the FAN_REPORT_PIDFD initialization flag is introduced. Link: https://lore.kernel.org/r/8872947dfe12ce8ae6e9a7f2d49ea29bc8006af0.1628398044.git.repnop@google.com Signed-off-by: Matthew Bobrowski <repnop@google.com> Reviewed-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Jan Kara <jack@suse.cz>
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parent
d3424c9bac
commit
0aca67bb7f
2 changed files with 90 additions and 67 deletions
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@ -173,7 +173,7 @@ static struct fanotify_event *get_one_event(struct fsnotify_group *group,
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size_t event_size = FAN_EVENT_METADATA_LEN;
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struct fanotify_event *event = NULL;
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struct fsnotify_event *fsn_event;
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unsigned int fid_mode = FAN_GROUP_FLAG(group, FANOTIFY_FID_BITS);
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unsigned int info_mode = FAN_GROUP_FLAG(group, FANOTIFY_INFO_MODES);
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pr_debug("%s: group=%p count=%zd\n", __func__, group, count);
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@ -183,8 +183,8 @@ static struct fanotify_event *get_one_event(struct fsnotify_group *group,
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goto out;
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event = FANOTIFY_E(fsn_event);
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if (fid_mode)
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event_size += fanotify_event_info_len(fid_mode, event);
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if (info_mode)
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event_size += fanotify_event_info_len(info_mode, event);
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if (event_size > count) {
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event = ERR_PTR(-EINVAL);
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@ -401,6 +401,86 @@ static int copy_fid_info_to_user(__kernel_fsid_t *fsid, struct fanotify_fh *fh,
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return info_len;
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}
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static int copy_info_records_to_user(struct fanotify_event *event,
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struct fanotify_info *info,
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unsigned int info_mode,
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char __user *buf, size_t count)
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{
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int ret, total_bytes = 0, info_type = 0;
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unsigned int fid_mode = info_mode & FANOTIFY_FID_BITS;
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/*
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* Event info records order is as follows: dir fid + name, child fid.
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*/
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if (fanotify_event_dir_fh_len(event)) {
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info_type = info->name_len ? FAN_EVENT_INFO_TYPE_DFID_NAME :
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FAN_EVENT_INFO_TYPE_DFID;
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ret = copy_fid_info_to_user(fanotify_event_fsid(event),
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fanotify_info_dir_fh(info),
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info_type,
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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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buf += ret;
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count -= ret;
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total_bytes += ret;
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}
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if (fanotify_event_object_fh_len(event)) {
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const char *dot = NULL;
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int dot_len = 0;
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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 ((fid_mode & FAN_REPORT_NAME) &&
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(event->mask & FAN_ONDIR)) {
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/*
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* With group flag FAN_REPORT_NAME, if name was not
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* recorded in an event on a directory, report the name
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* "." with info type DFID_NAME.
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*/
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info_type = FAN_EVENT_INFO_TYPE_DFID_NAME;
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dot = ".";
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dot_len = 1;
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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_fid_info_to_user(fanotify_event_fsid(event),
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fanotify_event_object_fh(event),
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info_type, dot, dot_len,
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buf, count);
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if (ret < 0)
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return ret;
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buf += ret;
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count -= ret;
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total_bytes += ret;
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}
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return total_bytes;
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}
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static ssize_t copy_event_to_user(struct fsnotify_group *group,
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struct fanotify_event *event,
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char __user *buf, size_t count)
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@ -408,15 +488,14 @@ 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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unsigned int info_mode = FAN_GROUP_FLAG(group, FANOTIFY_INFO_MODES);
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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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metadata.event_len = FAN_EVENT_METADATA_LEN +
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fanotify_event_info_len(fid_mode, event);
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fanotify_event_info_len(info_mode, event);
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metadata.metadata_len = FAN_EVENT_METADATA_LEN;
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metadata.vers = FANOTIFY_METADATA_VERSION;
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metadata.reserved = 0;
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@ -465,69 +544,11 @@ static ssize_t copy_event_to_user(struct fsnotify_group *group,
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if (f)
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fd_install(fd, f);
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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 = info->name_len ? FAN_EVENT_INFO_TYPE_DFID_NAME :
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FAN_EVENT_INFO_TYPE_DFID;
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ret = copy_fid_info_to_user(fanotify_event_fsid(event),
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fanotify_info_dir_fh(info),
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info_type,
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fanotify_info_name(info),
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info->name_len, buf, count);
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if (info_mode) {
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ret = copy_info_records_to_user(event, info, info_mode,
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buf, count);
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if (ret < 0)
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goto out_close_fd;
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buf += ret;
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count -= ret;
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}
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if (fanotify_event_object_fh_len(event)) {
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const char *dot = NULL;
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int dot_len = 0;
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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 ((fid_mode & FAN_REPORT_NAME) &&
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(event->mask & FAN_ONDIR)) {
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/*
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* With group flag FAN_REPORT_NAME, if name was not
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* recorded in an event on a directory, report the
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* name "." with info type DFID_NAME.
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*/
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info_type = FAN_EVENT_INFO_TYPE_DFID_NAME;
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dot = ".";
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dot_len = 1;
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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_fid_info_to_user(fanotify_event_fsid(event),
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fanotify_event_object_fh(event),
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info_type, dot, dot_len,
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buf, count);
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if (ret < 0)
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goto out_close_fd;
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buf += ret;
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count -= ret;
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}
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return metadata.event_len;
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@ -27,6 +27,8 @@ extern struct ctl_table fanotify_table[]; /* for sysctl */
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#define FANOTIFY_FID_BITS (FAN_REPORT_FID | FAN_REPORT_DFID_NAME)
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#define FANOTIFY_INFO_MODES (FANOTIFY_FID_BITS)
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/*
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* fanotify_init() flags that require CAP_SYS_ADMIN.
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* We do not allow unprivileged groups to request permission events.
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