selftests: splice: Check behavior of full and short splices

In order to help catch regressions in splice vs read behavior in certain
special files, test a few with various different kinds of internal
kernel helpers.

Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>

1 files changed, 56 insertions, 0 deletions

diff --git a/tools/testing/selftests/splice/short_splice_read.sh b/tools/testing/selftests/splice/short_splice_read.sh
new file mode 100755
index 000000000000..7810d3589d9a
--- /dev/null
+++ b/tools/testing/selftests/splice/short_splice_read.sh
@@ -0,0 +1,56 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+set -e
+
+ret=0
+
+do_splice()
+{
+	filename="$1"
+	bytes="$2"
+	expected="$3"
+
+	out=$(./splice_read "$filename" "$bytes" | cat)
+	if [ "$out" = "$expected" ] ; then
+		echo "ok: $filename $bytes"
+	else
+		echo "FAIL: $filename $bytes"
+		ret=1
+	fi
+}
+
+test_splice()
+{
+	filename="$1"
+
+	full=$(cat "$filename")
+	two=$(echo "$full" | grep -m1 . | cut -c-2)
+
+	# Make sure full splice has the same contents as a standard read.
+	do_splice "$filename" 4096 "$full"
+
+	# Make sure a partial splice see the first two characters.
+	do_splice "$filename" 2 "$two"
+}
+
+# proc_single_open(), seq_read()
+test_splice /proc/$$/limits
+# special open, seq_read()
+test_splice /proc/$$/comm
+
+# proc_handler, proc_dointvec_minmax
+test_splice /proc/sys/fs/nr_open
+# proc_handler, proc_dostring
+test_splice /proc/sys/kernel/modprobe
+# proc_handler, special read
+test_splice /proc/sys/kernel/version
+
+if ! [ -d /sys/module/test_module/sections ] ; then
+	modprobe test_module
+fi
+# kernfs, attr
+test_splice /sys/module/test_module/coresize
+# kernfs, binattr
+test_splice /sys/module/test_module/sections/.init.text
+
+exit $ret