Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Feedback-ID: iac594737:Fastmail
From:   Demi Marie Obenour <demi@invisiblethingslab.com>
To:     Alasdair Kergon <agk@redhat.com>,
        Mike Snitzer <snitzer@kernel.org>, dm-devel@redhat.com
Cc:     Demi Marie Obenour <demi@invisiblethingslab.com>,
        linux-kernel@vger.kernel.org
Subject: [PATCH 6/6] device-mapper: "." and ".." are not valid symlink names
Date:   Thu,  1 Jun 2023 17:24:55 -0400
Message-Id: <20230601212456.1533-7-demi@invisiblethingslab.com>
In-Reply-To: <20230601212456.1533-1-demi@invisiblethingslab.com>
References: <20230601212456.1533-1-demi@invisiblethingslab.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

Using either of these is going to greatly confuse userspace, as they are
not valid symlink names and so creating the usual /dev/mapper/NAME
symlink will not be possible.  As creating a device with either of these
names is almost certainly a userspace bug, just error out.

Signed-off-by: Demi Marie Obenour <demi@invisiblethingslab.com>
---
 drivers/md/dm-ioctl.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
index b12592bcb4b2b8513f5da6208fb545203534d7ff..adf0c4becc743e4ad59e1d6b0ef108ddd56f207d 100644
--- a/drivers/md/dm-ioctl.c
+++ b/drivers/md/dm-ioctl.c
@@ -771,8 +771,10 @@ static int check_name(const char *name)
 		return -EINVAL;
 	}
 
-	if (strcmp(name, DM_CONTROL_NODE) == 0) {
-		DMERR("device name cannot be \"%s\"", DM_CONTROL_NODE);
+	if (strcmp(name, DM_CONTROL_NODE) == 0 ||
+	    strcmp(name, ".") == 0 ||
+	    strcmp(name, "..") == 0) {
+		DMERR("device name cannot be \"%s\", \".\", or \"..\"", DM_CONTROL_NODE);
 		return -EINVAL;
 	}
 
-- 
Sincerely,
Demi Marie Obenour (she/her/hers)
Invisible Things Lab