linux-ext4 - [PATCH v8 16/32] fanotify: Require fid

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Date:   Mon, 18 Oct 2021 20:59:59 -0300
From:   Gabriel Krisman Bertazi <krisman@...labora.com>
To:     jack@...e.com, amir73il@...il.com
Cc:     djwong@...nel.org, tytso@....edu, david@...morbit.com,
        dhowells@...hat.com, khazhy@...gle.com,
        linux-fsdevel@...r.kernel.org, linux-ext4@...r.kernel.org,
        linux-api@...r.kernel.org,
        Gabriel Krisman Bertazi <krisman@...labora.com>,
        kernel@...labora.com, Jan Kara <jack@...e.cz>
Subject: [PATCH v8 16/32] fanotify: Require fid_mode for any non-fd event

Like inode events, FAN_FS_ERROR will require fid mode.  Therefore,
convert the verification during fanotify_mark(2) to require fid for any
non-fd event.  This means fid_mode will not only be required for inode
events, but for any event that doesn't provide a descriptor.

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

---
changes since v5:
  - Fix condition to include FANOTIFY_EVENT_FLAGS. (me)
  - Fix comment identation  (jan)
---
 fs/notify/fanotify/fanotify_user.c | 12 ++++++------
 include/linux/fanotify.h           |  3 +++
 2 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index adeae6d65e35..66ee3c2805c7 100644
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -1458,14 +1458,14 @@ static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask,
 		goto fput_and_out;
 
 	/*
-	 * Events with data type inode do not carry enough information to report
-	 * event->fd, so we do not allow setting a mask for inode events unless
-	 * group supports reporting fid.
-	 * inode events are not supported on a mount mark, because they do not
-	 * carry enough information (i.e. path) to be filtered by mount point.
+	 * Events that do not carry enough information to report
+	 * event->fd require a group that supports reporting fid.  Those
+	 * events are not supported on a mount mark, because they do not
+	 * carry enough information (i.e. path) to be filtered by mount
+	 * point.
 	 */
 	fid_mode = FAN_GROUP_FLAG(group, FANOTIFY_FID_BITS);
-	if (mask & FANOTIFY_INODE_EVENTS &&
+	if (mask & ~(FANOTIFY_FD_EVENTS|FANOTIFY_EVENT_FLAGS) &&
 	    (!fid_mode || mark_type == FAN_MARK_MOUNT))
 		goto fput_and_out;
 
diff --git a/include/linux/fanotify.h b/include/linux/fanotify.h
index eec3b7c40811..52d464802d99 100644
--- a/include/linux/fanotify.h
+++ b/include/linux/fanotify.h
@@ -84,6 +84,9 @@ extern struct ctl_table fanotify_table[]; /* for sysctl */
  */
 #define FANOTIFY_DIRENT_EVENTS	(FAN_MOVE | FAN_CREATE | FAN_DELETE)
 
+/* Events that can be reported with event->fd */
+#define FANOTIFY_FD_EVENTS (FANOTIFY_PATH_EVENTS | FANOTIFY_PERM_EVENTS)
+
 /* Events that can only be reported with data type FSNOTIFY_EVENT_INODE */
 #define FANOTIFY_INODE_EVENTS	(FANOTIFY_DIRENT_EVENTS | \
 				 FAN_ATTRIB | FAN_MOVE_SELF | FAN_DELETE_SELF)
-- 
2.33.0