generic: handle fs.verity.require_signatures being enabled

Most of the fs-verity tests fail if the fs.verity.require_signatures
sysctl has been set to 1.  Update them to set this sysctl to 0 at the
beginning of the test and restore it to its previous value at the end.

generic/577 intentionally sets this sysctl to 1.  Make it restore the
previous value at the end of the test rather than assuming it was 0.

Also simplify _require_fsverity_builtin_signatures() to just check for
the presence of the file /proc/sys/fs/verity/require_signatures rather
than check whether the fs-verity keyring is listed in /proc/keys.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Eryu Guan <guaneryu@gmail.com>
Signed-off-by: Eryu Guan <guaneryu@gmail.com>

common/verity

@@ -33,9 +33,12 @@ _require_scratch_verity()
 	# default.  E.g., ext4 only supports verity on extent-based files, so it
 	# doesn't work on ext3-style filesystems.  So, try actually using it.
 	echo foo > $SCRATCH_MNT/tmpfile
+	_disable_fsverity_signatures
 	if ! _fsv_enable $SCRATCH_MNT/tmpfile; then
+		_restore_fsverity_signatures
 		_notrun "$FSTYP verity isn't usable by default with these mkfs options"
 	fi
+	_restore_fsverity_signatures
 	rm -f $SCRATCH_MNT/tmpfile
 
 	_scratch_unmount
@@ -48,14 +51,40 @@ _require_scratch_verity()
 # Check for CONFIG_FS_VERITY_BUILTIN_SIGNATURES=y.
 _require_fsverity_builtin_signatures()
 {
-	if [ ! -e /proc/keys ]; then
+	if [ ! -e /proc/sys/fs/verity/require_signatures ]; then
-		_notrun "kernel doesn't support keyrings"
-	fi
-	if ! awk '{print $9}' /proc/keys | grep -q '^\.fs-verity:$'; then
 		_notrun "kernel doesn't support fs-verity builtin signatures"
 	fi
 }
 
+# Disable mandatory signatures for fs-verity files, if they are supported.
+_disable_fsverity_signatures()
+{
+	if [ -e /proc/sys/fs/verity/require_signatures ]; then
+		if [ -z "$FSVERITY_SIG_CTL_ORIG" ]; then
+			FSVERITY_SIG_CTL_ORIG=$(</proc/sys/fs/verity/require_signatures)
+		fi
+		echo 0 > /proc/sys/fs/verity/require_signatures
+	fi
+}
+
+# Enable mandatory signatures for fs-verity files.
+# This assumes that _require_fsverity_builtin_signatures() was called.
+_enable_fsverity_signatures()
+{
+	if [ -z "$FSVERITY_SIG_CTL_ORIG" ]; then
+		FSVERITY_SIG_CTL_ORIG=$(</proc/sys/fs/verity/require_signatures)
+	fi
+	echo 1 > /proc/sys/fs/verity/require_signatures
+}
+
+# Restore the original signature verification setting.
+_restore_fsverity_signatures()
+{
+        if [ -n "$FSVERITY_SIG_CTL_ORIG" ]; then
+                echo "$FSVERITY_SIG_CTL_ORIG" > /proc/sys/fs/verity/require_signatures
+        fi
+}
+
 _scratch_mkfs_verity()
 {
 	case $FSTYP in

tests/generic/572

@@ -23,6 +23,7 @@ trap "_cleanup; exit \$status" 0 1 2 3 15
 _cleanup()
 {
 	cd /
+	_restore_fsverity_signatures
 	rm -f $tmp.*
 }
 
@@ -38,6 +39,7 @@ rm -f $seqres.full
 _supported_fs generic
 _supported_os Linux
 _require_scratch_verity
+_disable_fsverity_signatures
 
 _scratch_mkfs_verity &>> $seqres.full
 _scratch_mount

tests/generic/573

@@ -19,6 +19,7 @@ trap "_cleanup; exit \$status" 0 1 2 3 15
 _cleanup()
 {
 	cd /
+	_restore_fsverity_signatures
 	rm -f $tmp.*
 }
 
@@ -36,6 +37,7 @@ _supported_os Linux
 _require_scratch_verity
 _require_user
 _require_chattr ia
+_disable_fsverity_signatures
 
 _scratch_mkfs_verity &>> $seqres.full
 _scratch_mount

tests/generic/574

@@ -21,6 +21,7 @@ trap "_cleanup; exit \$status" 0 1 2 3 15
 _cleanup()
 {
 	cd /
+	_restore_fsverity_signatures
 	rm -f $tmp.*
 }
 
@@ -36,6 +37,7 @@ rm -f $seqres.full
 _supported_fs generic
 _supported_os Linux
 _require_scratch_verity
+_disable_fsverity_signatures
 
 _scratch_mkfs_verity &>> $seqres.full
 _scratch_mount

tests/generic/575

@@ -20,6 +20,7 @@ trap "_cleanup; exit \$status" 0 1 2 3 15
 _cleanup()
 {
 	cd /
+	_restore_fsverity_signatures
 	rm -f $tmp.*
 }
 
@@ -38,6 +39,7 @@ _require_scratch_verity
 if [ $FSV_BLOCK_SIZE != 4096 ]; then
 	_notrun "4096-byte verity block size not supported on this platform"
 fi
+_disable_fsverity_signatures
 
 _scratch_mkfs_verity &>> $seqres.full
 _scratch_mount

tests/generic/576

@@ -19,6 +19,7 @@ trap "_cleanup; exit \$status" 0 1 2 3 15
 _cleanup()
 {
 	cd /
+	_restore_fsverity_signatures
 	rm -f $tmp.*
 }
 
@@ -37,6 +38,7 @@ _supported_os Linux
 _require_scratch_verity
 _require_scratch_encryption
 _require_command "$KEYCTL_PROG" keyctl
+_disable_fsverity_signatures
 
 _scratch_mkfs_encrypted_verity &>> $seqres.full
 _scratch_mount

tests/generic/577

@@ -17,8 +17,8 @@ trap "_cleanup; exit \$status" 0 1 2 3 15
 
 _cleanup()
 {
-	sysctl -w fs.verity.require_signatures=0 &>/dev/null
 	cd /
+	_restore_fsverity_signatures
 	rm -f $tmp.*
 }
 
@@ -71,7 +71,7 @@ $KEYCTL_PROG padd asymmetric '' %keyring:.fs-verity \
 	< $certfileder >> $seqres.full
 
 echo -e "\n# Enabling fs.verity.require_signatures"
-sysctl -w fs.verity.require_signatures=1
+_enable_fsverity_signatures
 
 echo -e "\n# Generating file and signing it for fs-verity"
 head -c 100000 /dev/zero > $fsv_orig_file
@@ -104,9 +104,9 @@ _fsv_enable $fsv_file |& _filter_scratch
 
 echo -e "\n# Opening verity file without signature (should fail)"
 reset_fsv_file
-sysctl -w fs.verity.require_signatures=0 &>> $seqres.full
+_disable_fsverity_signatures
 _fsv_enable $fsv_file
-sysctl -w fs.verity.require_signatures=1 &>> $seqres.full
+_enable_fsverity_signatures
 _scratch_cycle_mount
 md5sum $fsv_file |& _filter_scratch
 

tests/generic/577.out

@@ -7,7 +7,6 @@ QA output created by 577
 # Loading first certificate into fs-verity keyring
 
 # Enabling fs.verity.require_signatures
-fs.verity.require_signatures = 1
 
 # Generating file and signing it for fs-verity
 Signed file 'SCRATCH_MNT/file' (sha256:ecabbfca4efd69a721be824965da10d27900b109549f96687b35a4d91d810dac)

tests/generic/579

@@ -25,6 +25,7 @@ _cleanup()
 	touch $tmp.done
 	wait
 
+	_restore_fsverity_signatures
 	rm -f $tmp.*
 }
 
@@ -41,6 +42,7 @@ _supported_fs generic
 _supported_os Linux
 _require_scratch_verity
 _require_command "$KILLALL_PROG" killall
+_disable_fsverity_signatures
 
 _scratch_mkfs_verity &>> $seqres.full
 _scratch_mount