From f6706ce12401e228fa5e0ce80dfde56037d042af Mon Sep 17 00:00:00 2001
From: Luca Boccassi <bluca@debian.org>
Date: Sat, 8 Aug 2020 20:56:20 +0100
Subject: [PATCH] Add a test function to exercise concurrent activations

The issue can be reproduced very easily by starting 2 veritysetup processes
at the same time:

$ sudo veritysetup open -v ./img.raw img ./img.verity  & sudo veritysetup open -v ./img.raw img ./img.verity
[1] 814021
device-mapper: create ioctl on img CRYPT-VERITY-cea03b7bc5b94e088e5754ff33be71d6-img failed: Device or resource busy
Verity device detected corruption after activation.
Command successful.
Command failed with code -1 (wrong or missing parameters).

Note how veritysetup open is reporting -EINVAL as the return code.

After the fix:

$ sudo veritysetup open -v ./img.raw img ./img.verity  & sudo veritysetup open -v ./img.raw img ./img.verity
[1] 814649
Verity device detected corruption after activation.
Command successful.
Device img already exists.
Command failed with code -5 (device already exists or device is busy).
---
 tests/verity-compat-test | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/tests/verity-compat-test b/tests/verity-compat-test
index 4ce70f9f..d3bcdd99 100755
--- a/tests/verity-compat-test
+++ b/tests/verity-compat-test
@@ -350,6 +350,31 @@ function checkUserSpaceRepair()
 	echo "[OK]"
 }
 
+function check_concurrent() # $1 hash
+{
+	DEV_PARAMS="$LOOPDEV1 $LOOPDEV2"
+
+	# First check that with two sequential opens, we are returning the expected -EEXIST
+	$VERITYSETUP format $DEV_PARAMS >/dev/null 2>&1 || fail
+	$VERITYSETUP create $DEV_NAME $DEV_PARAMS $1 >/dev/null 2>&1 || fail
+	check_exists
+	$VERITYSETUP create $DEV_NAME $DEV_PARAMS $1 2>&1 >/dev/null | grep -q "Device $DEV_NAME already exists" || fail
+	$VERITYSETUP close $DEV_NAME >/dev/null 2>&1 || fail
+
+	# Then do two concurrent opens, and check that libdevmapper did not return -EINVAL, which is
+	# not gracefully recoverable. Either could fail depending on scheduling, so just check that
+	# the libdevmapper error does not appear in either of the outputs.
+	exec {out_1}< <($VERITYSETUP create -v $DEV_NAME $DEV_PARAMS $1 2>&1)
+	exec {out_2}< <($VERITYSETUP create -v $DEV_NAME $DEV_PARAMS $1 2>&1)
+	wait
+	cat <&${out_1} | grep -q "Command failed with code .* (wrong or missing parameters)" && fail
+	cat <&${out_2} | grep -q "Command failed with code .* (wrong or missing parameters)" && fail
+	check_exists
+	$VERITYSETUP close $DEV_NAME >/dev/null 2>&1 || fail
+
+	echo "[OK]"
+}
+
 [ $(id -u) != 0 ] && skip "WARNING: You must be root to run this test, test skipped."
 [ ! -x "$VERITYSETUP" ] && skip "Cannot find $VERITYSETUP, test skipped."
 
@@ -440,5 +465,9 @@ checkUserSpaceRepair -1  4096 2 0       0       3 10
 checkUserSpaceRepair 400 4096 2 2048000 0       2 1
 #checkUserSpaceRepair 500 4096 2 2457600 4915200 1 2 # FIXME
 
+echo "Verity concurrent opening tests."
+prepare 8192 1024
+check_concurrent 9de18652fe74edfb9b805aaed72ae2aa48f94333f1ba5c452ac33b1c39325174
+
 remove_mapping
 exit 0