[v5,21/22] fanotify: report parent fid + name + child fid
diff mbox series

Message ID 20200716084230.30611-22-amir73il@gmail.com
State New
Headers show
Series
  • fanotify events with name info
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Commit Message

Amir Goldstein July 16, 2020, 8:42 a.m. UTC
For a group with fanotify_init() flag FAN_REPORT_DFID_NAME, the parent
fid and name are reported for events on non-directory objects with an
info record of type FAN_EVENT_INFO_TYPE_DFID_NAME.

If the group also has the init flag FAN_REPORT_FID, the child fid
is also reported with another info record that follows the first info
record. The second info record is the same info record that would have
been reported to a group with only FAN_REPORT_FID flag.

When the child fid needs to be recorded, the variable size struct
fanotify_name_event is preallocated with enough space to store the
child fh between the dir fh and the name.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
---
 fs/notify/fanotify/fanotify.c      | 30 ++++++++++++++++++++++++++----
 fs/notify/fanotify/fanotify.h      |  8 +++++++-
 fs/notify/fanotify/fanotify_user.c |  3 ++-
 3 files changed, 35 insertions(+), 6 deletions(-)

Comments

Jan Kara July 16, 2020, 3:59 p.m. UTC | #1
On Thu 16-07-20 11:42:29, Amir Goldstein wrote:
> For a group with fanotify_init() flag FAN_REPORT_DFID_NAME, the parent
> fid and name are reported for events on non-directory objects with an
> info record of type FAN_EVENT_INFO_TYPE_DFID_NAME.
> 
> If the group also has the init flag FAN_REPORT_FID, the child fid
> is also reported with another info record that follows the first info
> record. The second info record is the same info record that would have
> been reported to a group with only FAN_REPORT_FID flag.
> 
> When the child fid needs to be recorded, the variable size struct
> fanotify_name_event is preallocated with enough space to store the
> child fh between the dir fh and the name.
> 
> Signed-off-by: Amir Goldstein <amir73il@gmail.com>
> ---
>  fs/notify/fanotify/fanotify.c      | 30 ++++++++++++++++++++++++++----
>  fs/notify/fanotify/fanotify.h      |  8 +++++++-
>  fs/notify/fanotify/fanotify_user.c |  3 ++-
>  3 files changed, 35 insertions(+), 6 deletions(-)
> 
> diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
> index c77b37eb33a9..1d8eb886fe08 100644
> --- a/fs/notify/fanotify/fanotify.c
> +++ b/fs/notify/fanotify/fanotify.c
> @@ -479,15 +479,22 @@ static struct fanotify_event *fanotify_alloc_fid_event(struct inode *id,
>  static struct fanotify_event *fanotify_alloc_name_event(struct inode *id,
>  							__kernel_fsid_t *fsid,
>  							const struct qstr *file_name,
> +							struct inode *child,
>  							gfp_t gfp)
>  {
>  	struct fanotify_name_event *fne;
>  	struct fanotify_info *info;
> -	struct fanotify_fh *dfh;
> +	struct fanotify_fh *dfh, *ffh;
>  	unsigned int dir_fh_len = fanotify_encode_fh_len(id);
> +	unsigned int child_fh_len = fanotify_encode_fh_len(child);
>  	unsigned int size;
>  
> +	if (WARN_ON_ONCE(dir_fh_len % FANOTIFY_FH_HDR_LEN))
> +		child_fh_len = 0;
> +

Why this check? Do you want to check everything is 4-byte aligned? But then
FANOTIFY_FH_HDR_LEN works mostly by accident...

								Honza
Amir Goldstein July 16, 2020, 4:08 p.m. UTC | #2
On Thu, Jul 16, 2020 at 6:59 PM Jan Kara <jack@suse.cz> wrote:
>
> On Thu 16-07-20 11:42:29, Amir Goldstein wrote:
> > For a group with fanotify_init() flag FAN_REPORT_DFID_NAME, the parent
> > fid and name are reported for events on non-directory objects with an
> > info record of type FAN_EVENT_INFO_TYPE_DFID_NAME.
> >
> > If the group also has the init flag FAN_REPORT_FID, the child fid
> > is also reported with another info record that follows the first info
> > record. The second info record is the same info record that would have
> > been reported to a group with only FAN_REPORT_FID flag.
> >
> > When the child fid needs to be recorded, the variable size struct
> > fanotify_name_event is preallocated with enough space to store the
> > child fh between the dir fh and the name.
> >
> > Signed-off-by: Amir Goldstein <amir73il@gmail.com>
> > ---
> >  fs/notify/fanotify/fanotify.c      | 30 ++++++++++++++++++++++++++----
> >  fs/notify/fanotify/fanotify.h      |  8 +++++++-
> >  fs/notify/fanotify/fanotify_user.c |  3 ++-
> >  3 files changed, 35 insertions(+), 6 deletions(-)
> >
> > diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
> > index c77b37eb33a9..1d8eb886fe08 100644
> > --- a/fs/notify/fanotify/fanotify.c
> > +++ b/fs/notify/fanotify/fanotify.c
> > @@ -479,15 +479,22 @@ static struct fanotify_event *fanotify_alloc_fid_event(struct inode *id,
> >  static struct fanotify_event *fanotify_alloc_name_event(struct inode *id,
> >                                                       __kernel_fsid_t *fsid,
> >                                                       const struct qstr *file_name,
> > +                                                     struct inode *child,
> >                                                       gfp_t gfp)
> >  {
> >       struct fanotify_name_event *fne;
> >       struct fanotify_info *info;
> > -     struct fanotify_fh *dfh;
> > +     struct fanotify_fh *dfh, *ffh;
> >       unsigned int dir_fh_len = fanotify_encode_fh_len(id);
> > +     unsigned int child_fh_len = fanotify_encode_fh_len(child);
> >       unsigned int size;
> >
> > +     if (WARN_ON_ONCE(dir_fh_len % FANOTIFY_FH_HDR_LEN))
> > +             child_fh_len = 0;
> > +
>
> Why this check? Do you want to check everything is 4-byte aligned? But then
> FANOTIFY_FH_HDR_LEN works mostly by accident...

Good catch.
That's indeed a mistake.
Should be % 4 which is expected because
...
        return dwords << 2;

If you think that is over defensive, you can drop it.

Thanks,
Amir.

Patch
diff mbox series

diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
index c77b37eb33a9..1d8eb886fe08 100644
--- a/fs/notify/fanotify/fanotify.c
+++ b/fs/notify/fanotify/fanotify.c
@@ -479,15 +479,22 @@  static struct fanotify_event *fanotify_alloc_fid_event(struct inode *id,
 static struct fanotify_event *fanotify_alloc_name_event(struct inode *id,
 							__kernel_fsid_t *fsid,
 							const struct qstr *file_name,
+							struct inode *child,
 							gfp_t gfp)
 {
 	struct fanotify_name_event *fne;
 	struct fanotify_info *info;
-	struct fanotify_fh *dfh;
+	struct fanotify_fh *dfh, *ffh;
 	unsigned int dir_fh_len = fanotify_encode_fh_len(id);
+	unsigned int child_fh_len = fanotify_encode_fh_len(child);
 	unsigned int size;
 
+	if (WARN_ON_ONCE(dir_fh_len % FANOTIFY_FH_HDR_LEN))
+		child_fh_len = 0;
+
 	size = sizeof(*fne) + FANOTIFY_FH_HDR_LEN + dir_fh_len;
+	if (child_fh_len)
+		size += FANOTIFY_FH_HDR_LEN + child_fh_len;
 	if (file_name)
 		size += file_name->len + 1;
 	fne = kmalloc(size, gfp);
@@ -500,11 +507,15 @@  static struct fanotify_event *fanotify_alloc_name_event(struct inode *id,
 	fanotify_info_init(info);
 	dfh = fanotify_info_dir_fh(info);
 	info->dir_fh_totlen = fanotify_encode_fh(dfh, id, dir_fh_len, 0);
+	if (child_fh_len) {
+		ffh = fanotify_info_file_fh(info);
+		info->file_fh_totlen = fanotify_encode_fh(ffh, child, child_fh_len, 0);
+	}
 	if (file_name)
 		fanotify_info_copy_name(info, file_name);
 
-	pr_debug("%s: ino=%lu size=%u dir_fh_len=%u name_len=%u name='%.*s'\n",
-		 __func__, id->i_ino, size, dir_fh_len,
+	pr_debug("%s: ino=%lu size=%u dir_fh_len=%u child_fh_len=%u name_len=%u name='%.*s'\n",
+		 __func__, id->i_ino, size, dir_fh_len, child_fh_len,
 		 info->name_len, info->name_len, fanotify_info_name(info));
 
 	return &fne->fae;
@@ -521,9 +532,19 @@  static struct fanotify_event *fanotify_alloc_event(struct fsnotify_group *group,
 	struct inode *id = fanotify_fid_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);
+	struct inode *child = NULL;
 	bool name_event = false;
 
 	if ((fid_mode & FAN_REPORT_DIR_FID) && dir) {
+		/*
+		 * With both flags FAN_REPORT_DIR_FID and FAN_REPORT_FID, we
+		 * report the child fid for events reported on a non-dir child
+		 * in addition to reporting the parent fid and child name.
+		 */
+		if ((fid_mode & FAN_REPORT_FID) &&
+		    (mask & FAN_EVENT_ON_CHILD) && !(mask & FAN_ONDIR))
+			child = id;
+
 		id = fanotify_dfid_inode(mask, data, data_type, dir);
 
 		/*
@@ -559,7 +580,8 @@  static struct fanotify_event *fanotify_alloc_event(struct fsnotify_group *group,
 	if (fanotify_is_perm_event(mask)) {
 		event = fanotify_alloc_perm_event(path, gfp);
 	} else if (name_event && file_name) {
-		event = fanotify_alloc_name_event(id, fsid, file_name, gfp);
+		event = fanotify_alloc_name_event(id, fsid, file_name, child,
+						  gfp);
 	} else if (fid_mode) {
 		event = fanotify_alloc_fid_event(id, fsid, gfp);
 	} else {
diff --git a/fs/notify/fanotify/fanotify.h b/fs/notify/fanotify/fanotify.h
index 12c204b1489f..896c819a1786 100644
--- a/fs/notify/fanotify/fanotify.h
+++ b/fs/notify/fanotify/fanotify.h
@@ -193,6 +193,8 @@  static inline struct fanotify_fh *fanotify_event_object_fh(
 {
 	if (event->type == FANOTIFY_EVENT_TYPE_FID)
 		return &FANOTIFY_FE(event)->object_fh;
+	else if (event->type == FANOTIFY_EVENT_TYPE_FID_NAME)
+		return fanotify_info_file_fh(&FANOTIFY_NE(event)->info);
 	else
 		return NULL;
 }
@@ -208,9 +210,13 @@  static inline struct fanotify_info *fanotify_event_info(
 
 static inline int fanotify_event_object_fh_len(struct fanotify_event *event)
 {
+	struct fanotify_info *info = fanotify_event_info(event);
 	struct fanotify_fh *fh = fanotify_event_object_fh(event);
 
-	return fh ? fh->len : 0;
+	if (info)
+		return info->file_fh_totlen ? fh->len : 0;
+	else
+		return fh ? fh->len : 0;
 }
 
 static inline int fanotify_event_dir_fh_len(struct fanotify_event *event)
diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index 6b839790cb42..be328d7ee283 100644
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -956,14 +956,15 @@  SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags)
 		return -EINVAL;
 
 	/*
-	 * Reporting either object fid or dir fid.
 	 * Child name is reported with parent fid so requires dir fid.
+	 * If reporting child name, we can report both child fid and dir fid.
 	 */
 	switch (fid_mode) {
 	case 0:
 	case FAN_REPORT_FID:
 	case FAN_REPORT_DIR_FID:
 	case FAN_REPORT_DFID_NAME:
+	case FAN_REPORT_DFID_NAME | FAN_REPORT_FID:
 		break;
 	default:
 		return -EINVAL;