Re: [PATCH v3 4/5] fanotify/fanotify_user.c: introduce a generic info record copying helper
From: Amir Goldstein <amir73il@gmail.com>
Date: 2021-07-21 06:35:29
Also in:
linux-fsdevel
On Wed, Jul 21, 2021 at 9:18 AM Matthew Bobrowski [off-list ref] wrote:
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. Signed-off-by: Matthew Bobrowski <repnop@google.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
quoted hunk ↗ jump to hunk
--- fs/notify/fanotify/fanotify_user.c | 155 ++++++++++++++++------------- include/linux/fanotify.h | 2 + 2 files changed, 90 insertions(+), 67 deletions(-)diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c index 182fea255376..d19f70b2c24c 100644 --- a/fs/notify/fanotify/fanotify_user.c +++ b/fs/notify/fanotify/fanotify_user.c@@ -173,7 +173,7 @@ static struct fanotify_event *get_one_event(struct fsnotify_group *group, size_t event_size = FAN_EVENT_METADATA_LEN; struct fanotify_event *event = NULL; struct fsnotify_event *fsn_event; - unsigned int fid_mode = FAN_GROUP_FLAG(group, FANOTIFY_FID_BITS); + unsigned int info_mode = FAN_GROUP_FLAG(group, FANOTIFY_INFO_MODES); pr_debug("%s: group=%p count=%zd\n", __func__, group, count);@@ -183,8 +183,8 @@ static struct fanotify_event *get_one_event(struct fsnotify_group *group, goto out; event = FANOTIFY_E(fsn_event); - if (fid_mode) - event_size += fanotify_event_info_len(fid_mode, event); + if (info_mode) + event_size += fanotify_event_info_len(info_mode, event); if (event_size > count) { event = ERR_PTR(-EINVAL);@@ -401,6 +401,86 @@ static int copy_fid_info_to_user(__kernel_fsid_t *fsid, struct fanotify_fh *fh, return info_len; } +static int copy_info_records_to_user(struct fanotify_event *event, + struct fanotify_info *info, + unsigned int info_mode, + char __user *buf, size_t count) +{ + int ret, total_bytes = 0, info_type = 0; + unsigned int fid_mode = info_mode & FANOTIFY_FID_BITS; + + /* + * Event info records order is as follows: dir fid + name, child fid. + */ + if (fanotify_event_dir_fh_len(event)) { + info_type = info->name_len ? FAN_EVENT_INFO_TYPE_DFID_NAME : + FAN_EVENT_INFO_TYPE_DFID; + ret = copy_fid_info_to_user(fanotify_event_fsid(event), + fanotify_info_dir_fh(info), + info_type, + fanotify_info_name(info), + info->name_len, buf, count); + if (ret < 0) + return ret; + + buf += ret; + count -= ret; + total_bytes += ret; + } + + if (fanotify_event_object_fh_len(event)) { + const char *dot = NULL; + int dot_len = 0; + + 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 ((fid_mode & FAN_REPORT_NAME) && + (event->mask & FAN_ONDIR)) { + /* + * With group flag FAN_REPORT_NAME, if name was not + * recorded in an event on a directory, report the name + * "." with info type DFID_NAME. + */ + info_type = FAN_EVENT_INFO_TYPE_DFID_NAME; + dot = "."; + dot_len = 1; + } 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 + * modificatio\ n 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_fid_info_to_user(fanotify_event_fsid(event), + fanotify_event_object_fh(event), + info_type, dot, dot_len, + buf, count); + if (ret < 0) + return ret; + + buf += ret; + count -= ret; + total_bytes += ret; + } + + return total_bytes; +} + static ssize_t copy_event_to_user(struct fsnotify_group *group, struct fanotify_event *event, char __user *buf, size_t count)@@ -408,15 +488,14 @@ 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); + unsigned int info_mode = FAN_GROUP_FLAG(group, FANOTIFY_INFO_MODES); struct file *f = NULL; int ret, fd = FAN_NOFD; - int info_type = 0; pr_debug("%s: group=%p event=%p\n", __func__, group, event); metadata.event_len = FAN_EVENT_METADATA_LEN + - fanotify_event_info_len(fid_mode, event); + fanotify_event_info_len(info_mode, event); metadata.metadata_len = FAN_EVENT_METADATA_LEN; metadata.vers = FANOTIFY_METADATA_VERSION; metadata.reserved = 0;@@ -465,69 +544,11 @@ static ssize_t copy_event_to_user(struct fsnotify_group *group, if (f) fd_install(fd, f); - /* Event info records order is: dir fid + name, child fid */ - if (fanotify_event_dir_fh_len(event)) { - info_type = info->name_len ? FAN_EVENT_INFO_TYPE_DFID_NAME : - FAN_EVENT_INFO_TYPE_DFID; - ret = copy_fid_info_to_user(fanotify_event_fsid(event), - fanotify_info_dir_fh(info), - info_type, - fanotify_info_name(info), - info->name_len, buf, count); - if (ret < 0) - goto out_close_fd; - - buf += ret; - count -= ret; - } - - if (fanotify_event_object_fh_len(event)) { - const char *dot = NULL; - int dot_len = 0; - - 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 ((fid_mode & FAN_REPORT_NAME) && - (event->mask & FAN_ONDIR)) { - /* - * With group flag FAN_REPORT_NAME, if name was not - * recorded in an event on a directory, report the - * name "." with info type DFID_NAME. - */ - info_type = FAN_EVENT_INFO_TYPE_DFID_NAME; - dot = "."; - dot_len = 1; - } 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_fid_info_to_user(fanotify_event_fsid(event), - fanotify_event_object_fh(event), - info_type, dot, dot_len, - buf, count); + if (info_mode) { + ret = copy_info_records_to_user(event, info, info_mode, + buf, count); if (ret < 0) goto out_close_fd; - - buf += ret; - count -= ret; } return metadata.event_len;diff --git a/include/linux/fanotify.h b/include/linux/fanotify.h index a16dbeced152..10a7e26ddba6 100644 --- a/include/linux/fanotify.h +++ b/include/linux/fanotify.h@@ -27,6 +27,8 @@ extern struct ctl_table fanotify_table[]; /* for sysctl */ #define FANOTIFY_FID_BITS (FAN_REPORT_FID | FAN_REPORT_DFID_NAME) +#define FANOTIFY_INFO_MODES (FANOTIFY_FID_BITS) + /* * fanotify_init() flags that require CAP_SYS_ADMIN. * We do not allow unprivileged groups to request permission events. --2.32.0.432.gabb21c7263-goog /M