linux-ext4 - [PATCH v9 28/31] fanotify: Allow users to request FAN_FS

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Date:   Mon, 25 Oct 2021 16:27:43 -0300
From:   Gabriel Krisman Bertazi <krisman@...labora.com>
To:     amir73il@...il.com, jack@...e.com
Cc:     djwong@...nel.org, tytso@....edu, david@...morbit.com,
        dhowells@...hat.com, khazhy@...gle.com,
        linux-fsdevel@...r.kernel.org, linux-api@...r.kernel.org,
        linux-ext4@...r.kernel.org,
        Gabriel Krisman Bertazi <krisman@...labora.com>,
        kernel@...labora.com, Jan Kara <jack@...e.cz>
Subject: [PATCH v9 28/31] fanotify: Allow users to request FAN_FS_ERROR events

Wire up the FAN_FS_ERROR event in the fanotify_mark syscall, allowing
user space to request the monitoring of FAN_FS_ERROR events.

These events are limited to filesystem marks, so check it is the
case in the syscall handler.

Reviewed-by: Amir Goldstein <amir73il@...il.com>
Reviewed-by: Jan Kara <jack@...e.cz>
Signed-off-by: Gabriel Krisman Bertazi <krisman@...labora.com>

---
Changes since v7:
  - Move the verification closer to similar code (Amir)
---
 fs/notify/fanotify/fanotify.c      | 2 +-
 fs/notify/fanotify/fanotify_user.c | 4 ++++
 include/linux/fanotify.h           | 6 +++++-
 3 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
index af61425e6e3b..b6091775aa6e 100644
--- a/fs/notify/fanotify/fanotify.c
+++ b/fs/notify/fanotify/fanotify.c
@@ -822,7 +822,7 @@ static int fanotify_handle_event(struct fsnotify_group *group, u32 mask,
 	BUILD_BUG_ON(FAN_OPEN_EXEC_PERM != FS_OPEN_EXEC_PERM);
 	BUILD_BUG_ON(FAN_FS_ERROR != FS_ERROR);
 
-	BUILD_BUG_ON(HWEIGHT32(ALL_FANOTIFY_EVENT_BITS) != 19);
+	BUILD_BUG_ON(HWEIGHT32(ALL_FANOTIFY_EVENT_BITS) != 20);
 
 	mask = fanotify_group_event_mask(group, iter_info, mask, data,
 					 data_type, dir);
diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index 97ec5b005b50..77a77064f3c9 100644
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -1519,6 +1519,10 @@ static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask,
 	    group->priority == FS_PRIO_0)
 		goto fput_and_out;
 
+	if (mask & FAN_FS_ERROR &&
+	    mark_type != FAN_MARK_FILESYSTEM)
+		goto fput_and_out;
+
 	/*
 	 * Events that do not carry enough information to report
 	 * event->fd require a group that supports reporting fid.  Those
diff --git a/include/linux/fanotify.h b/include/linux/fanotify.h
index 52d464802d99..616af2ea20f3 100644
--- a/include/linux/fanotify.h
+++ b/include/linux/fanotify.h
@@ -91,9 +91,13 @@ extern struct ctl_table fanotify_table[]; /* for sysctl */
 #define FANOTIFY_INODE_EVENTS	(FANOTIFY_DIRENT_EVENTS | \
 				 FAN_ATTRIB | FAN_MOVE_SELF | FAN_DELETE_SELF)
 
+/* Events that can only be reported with data type FSNOTIFY_EVENT_ERROR */
+#define FANOTIFY_ERROR_EVENTS	(FAN_FS_ERROR)
+
 /* Events that user can request to be notified on */
 #define FANOTIFY_EVENTS		(FANOTIFY_PATH_EVENTS | \
-				 FANOTIFY_INODE_EVENTS)
+				 FANOTIFY_INODE_EVENTS | \
+				 FANOTIFY_ERROR_EVENTS)
 
 /* Events that require a permission response from user */
 #define FANOTIFY_PERM_EVENTS	(FAN_OPEN_PERM | FAN_ACCESS_PERM | \
-- 
2.33.0