linux-kernel - [PATCH 3/4 v5 RESEND] devpts: comment devpts

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20180313165527.24038-4-christian.brauner@ubuntu.com>
Date:   Tue, 13 Mar 2018 17:55:26 +0100
From:   Christian Brauner <christian.brauner@...ntu.com>
To:     viro@...iv.linux.org.uk, linux-kernel@...r.kernel.org,
        ebiederm@...ssion.com, torvalds@...ux-foundation.org,
        gregkh@...uxfoundation.org
Cc:     containers@...ts.linux-foundation.org,
        Christian Brauner <christian.brauner@...ntu.com>
Subject: [PATCH 3/4 v5 RESEND] devpts: comment devpts_mntget()

Signed-off-by: Christian Brauner <christian.brauner@...ntu.com>
---
ChangeLog v4->v5:
* patch added
ChangeLog v3->v4:
* patch not present
ChangeLog v2->v3:
* patch not present
ChangeLog v1->v2:
* patch not present
ChangeLog v0->v1:
* patch not present
---
 fs/devpts/inode.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/fs/devpts/inode.c b/fs/devpts/inode.c
index 542364bf923e..e072e955ce33 100644
--- a/fs/devpts/inode.c
+++ b/fs/devpts/inode.c
@@ -152,6 +152,24 @@ static int devpts_ptmx_path(struct path *path)
 	return 0;
 }
 
+/*
+ * Try to find a suitable devpts filesystem. We support the following
+ * scenarios:
+ * - The ptmx device node is located in the same directory as the devpts
+ *   mount where the pts device nodes are located.
+ *   This is e.g. the case when calling open on the /dev/pts/ptmx device
+ *   node when the devpts filesystem is mounted at /dev/pts.
+ * - The ptmx device node is located outside the devpts filesystem mount
+ *   where the pts device nodes are located. For example, the ptmx device
+ *   is a symlink, separate device node, or bind-mount.
+ *   A supported scenario is bind-mounting /dev/pts/ptmx to /dev/ptmx and
+ *   then calling open on /dev/ptmx. In this case a suitable pts
+ *   subdirectory can be found in the common parent directory /dev of the
+ *   devpts mount and the ptmx bind-mount, after resolving the /dev/ptmx
+ *   bind-mount.
+ *   If no suitable pts subdirectory can be found this function will fail.
+ *   This is e.g. the case when bind-mounting /dev/pts/ptmx to /ptmx.
+ */
 struct vfsmount *devpts_mntget(struct file *filp, struct pts_fs_info *fsi)
 {
 	struct path path;
-- 
2.15.1