This is a note to let you know that I've just added the patch titled
fanotify: introduce a generic info record copying helper
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
fanotify-introduce-a-generic-info-record-copying-hel.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit ab7ee415f6d8b5b76b302f302236e91541f38ee3
Author: Matthew Bobrowski <repnop@xxxxxxxxxx>
Date: Sun Aug 8 15:25:58 2021 +1000
fanotify: introduce a generic info record copying helper
[ Upstream commit 0aca67bb7f0d8c997dfef8ff0bfeb0afb361f0e6 ]
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@xxxxxxxxxx
Signed-off-by: Matthew Bobrowski <repnop@xxxxxxxxxx>
Reviewed-by: Amir Goldstein <amir73il@xxxxxxxxx>
Signed-off-by: Jan Kara <jack@xxxxxxx>
[ cel: adjusted to apply to v5.10.y ]
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index 74b51dab2cdce..83405949a71b2 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);
@@ -401,68 +401,17 @@ static int copy_fid_info_to_user(__kernel_fsid_t *fsid, struct fanotify_fh *fh,
return info_len;
}
-static ssize_t copy_event_to_user(struct fsnotify_group *group,
- struct fanotify_event *event,
- char __user *buf, size_t count)
+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)
{
- 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);
-
- metadata.event_len = FAN_EVENT_METADATA_LEN +
- fanotify_event_info_len(fid_mode, event);
- metadata.metadata_len = FAN_EVENT_METADATA_LEN;
- metadata.vers = FANOTIFY_METADATA_VERSION;
- metadata.reserved = 0;
- metadata.mask = event->mask & FANOTIFY_OUTGOING_EVENTS;
- metadata.pid = pid_vnr(event->pid);
- /*
- * For an unprivileged listener, event->pid can be used to identify the
- * events generated by the listener process itself, without disclosing
- * the pids of other processes.
- */
- if (FAN_GROUP_FLAG(group, FANOTIFY_UNPRIV) &&
- task_tgid(current) != event->pid)
- metadata.pid = 0;
-
- /*
- * For now, fid mode is required for an unprivileged listener and
- * fid mode does not report fd in events. Keep this check anyway
- * for safety in case fid mode requirement is relaxed in the future
- * to allow unprivileged listener to get events with no fd and no fid.
- */
- if (!FAN_GROUP_FLAG(group, FANOTIFY_UNPRIV) &&
- path && path->mnt && path->dentry) {
- fd = create_fd(group, path, &f);
- if (fd < 0)
- return fd;
- }
- metadata.fd = fd;
+ int ret, total_bytes = 0, info_type = 0;
+ unsigned int fid_mode = info_mode & FANOTIFY_FID_BITS;
- ret = -EFAULT;
/*
- * Sanity check copy size in case get_one_event() and
- * event_len sizes ever get out of sync.
+ * Event info records order is as follows: dir fid + name, child fid.
*/
- if (WARN_ON_ONCE(metadata.event_len > count))
- goto out_close_fd;
-
- if (copy_to_user(buf, &metadata, FAN_EVENT_METADATA_LEN))
- goto out_close_fd;
-
- buf += FAN_EVENT_METADATA_LEN;
- count -= FAN_EVENT_METADATA_LEN;
-
- if (fanotify_is_perm_event(event->mask))
- FANOTIFY_PERM(event)->fd = fd;
-
- /* 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;
@@ -472,10 +421,11 @@ static ssize_t copy_event_to_user(struct fsnotify_group *group,
fanotify_info_name(info),
info->name_len, buf, count);
if (ret < 0)
- goto out_close_fd;
+ return ret;
buf += ret;
count -= ret;
+ total_bytes += ret;
}
if (fanotify_event_object_fh_len(event)) {
@@ -492,8 +442,8 @@ static ssize_t copy_event_to_user(struct fsnotify_group *group,
(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.
+ * recorded in an event on a directory, report the name
+ * "." with info type DFID_NAME.
*/
info_type = FAN_EVENT_INFO_TYPE_DFID_NAME;
dot = ".";
@@ -521,10 +471,81 @@ static ssize_t copy_event_to_user(struct fsnotify_group *group,
info_type, dot, dot_len,
buf, count);
if (ret < 0)
- goto out_close_fd;
+ 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)
+{
+ struct fanotify_event_metadata metadata;
+ struct path *path = fanotify_event_path(event);
+ struct fanotify_info *info = fanotify_event_info(event);
+ unsigned int info_mode = FAN_GROUP_FLAG(group, FANOTIFY_INFO_MODES);
+ struct file *f = NULL;
+ int ret, fd = FAN_NOFD;
+
+ pr_debug("%s: group=%p event=%p\n", __func__, group, event);
+
+ metadata.event_len = FAN_EVENT_METADATA_LEN +
+ fanotify_event_info_len(info_mode, event);
+ metadata.metadata_len = FAN_EVENT_METADATA_LEN;
+ metadata.vers = FANOTIFY_METADATA_VERSION;
+ metadata.reserved = 0;
+ metadata.mask = event->mask & FANOTIFY_OUTGOING_EVENTS;
+ metadata.pid = pid_vnr(event->pid);
+ /*
+ * For an unprivileged listener, event->pid can be used to identify the
+ * events generated by the listener process itself, without disclosing
+ * the pids of other processes.
+ */
+ if (FAN_GROUP_FLAG(group, FANOTIFY_UNPRIV) &&
+ task_tgid(current) != event->pid)
+ metadata.pid = 0;
+
+ /*
+ * For now, fid mode is required for an unprivileged listener and
+ * fid mode does not report fd in events. Keep this check anyway
+ * for safety in case fid mode requirement is relaxed in the future
+ * to allow unprivileged listener to get events with no fd and no fid.
+ */
+ if (!FAN_GROUP_FLAG(group, FANOTIFY_UNPRIV) &&
+ path && path->mnt && path->dentry) {
+ fd = create_fd(group, path, &f);
+ if (fd < 0)
+ return fd;
+ }
+ metadata.fd = fd;
+
+ ret = -EFAULT;
+ /*
+ * Sanity check copy size in case get_one_event() and
+ * event_len sizes ever get out of sync.
+ */
+ if (WARN_ON_ONCE(metadata.event_len > count))
+ goto out_close_fd;
+
+ if (copy_to_user(buf, &metadata, FAN_EVENT_METADATA_LEN))
+ goto out_close_fd;
+
+ buf += FAN_EVENT_METADATA_LEN;
+ count -= FAN_EVENT_METADATA_LEN;
+
+ if (fanotify_is_perm_event(event->mask))
+ FANOTIFY_PERM(event)->fd = fd;
+
+ if (info_mode) {
+ ret = copy_info_records_to_user(event, info, info_mode,
+ buf, count);
+ if (ret < 0)
+ goto out_close_fd;
}
if (f)
diff --git a/include/linux/fanotify.h b/include/linux/fanotify.h
index a16dbeced1528..10a7e26ddba6c 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.
