From: Kees Cook <keescook@xxxxxxxxxxxx>
[ Upstream commit 6daf076b717d189f4d02a303d45edd5732341ec1 ]
Some pseudo-filesystems do not have an explicit splice fops since adding
commit 36e2c7421f02 ("fs: don't allow splice read/write without explicit ops"),
and now will reject attempts to use splice() in those filesystem paths.
Reported-by: kernel test robot <rong.a.chen@xxxxxxxxx>
Link: https://lore.kernel.org/lkml/202009181443.C2179FB@keescook/
Fixes: 36e2c7421f02 ("fs: don't allow splice read/write without explicit ops")
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Shuah Khan <shuah@xxxxxxxxxx>
Cc: linux-kselftest@xxxxxxxxxxxxxxx
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
Signed-off-by: Shuah Khan <skhan@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
.../selftests/splice/short_splice_read.sh | 119 ++++++++++++++----
1 file changed, 98 insertions(+), 21 deletions(-)
diff --git a/tools/testing/selftests/splice/short_splice_read.sh b/tools/testing/selftests/splice/short_splice_read.sh
index 7810d3589d9a..22b6c8910b18 100755
--- a/tools/testing/selftests/splice/short_splice_read.sh
+++ b/tools/testing/selftests/splice/short_splice_read.sh
@@ -1,21 +1,87 @@
#!/bin/sh
# SPDX-License-Identifier: GPL-2.0
+#
+# Test for mishandling of splice() on pseudofilesystems, which should catch
+# bugs like 11990a5bd7e5 ("module: Correctly truncate sysfs sections output")
+#
+# Since splice fallback was removed as part of the set_fs() rework, many of these
+# tests expect to fail now. See https://lore.kernel.org/lkml/202009181443.C2179FB@keescook/
set -e
+DIR=$(dirname "$0")
+
ret=0
+expect_success()
+{
+ title="$1"
+ shift
+
+ echo "" >&2
+ echo "$title ..." >&2
+
+ set +e
+ "$@"
+ rc=$?
+ set -e
+
+ case "$rc" in
+ 0)
+ echo "ok: $title succeeded" >&2
+ ;;
+ 1)
+ echo "FAIL: $title should work" >&2
+ ret=$(( ret + 1 ))
+ ;;
+ *)
+ echo "FAIL: something else went wrong" >&2
+ ret=$(( ret + 1 ))
+ ;;
+ esac
+}
+
+expect_failure()
+{
+ title="$1"
+ shift
+
+ echo "" >&2
+ echo "$title ..." >&2
+
+ set +e
+ "$@"
+ rc=$?
+ set -e
+
+ case "$rc" in
+ 0)
+ echo "FAIL: $title unexpectedly worked" >&2
+ ret=$(( ret + 1 ))
+ ;;
+ 1)
+ echo "ok: $title correctly failed" >&2
+ ;;
+ *)
+ echo "FAIL: something else went wrong" >&2
+ ret=$(( ret + 1 ))
+ ;;
+ esac
+}
+
do_splice()
{
filename="$1"
bytes="$2"
expected="$3"
+ report="$4"
- out=$(./splice_read "$filename" "$bytes" | cat)
+ out=$("$DIR"/splice_read "$filename" "$bytes" | cat)
if [ "$out" = "$expected" ] ; then
- echo "ok: $filename $bytes"
+ echo " matched $report" >&2
+ return 0
else
- echo "FAIL: $filename $bytes"
- ret=1
+ echo " no match: '$out' vs $report" >&2
+ return 1
fi
}
@@ -23,34 +89,45 @@ test_splice()
{
filename="$1"
+ echo " checking $filename ..." >&2
+
full=$(cat "$filename")
+ rc=$?
+ if [ $rc -ne 0 ] ; then
+ return 2
+ fi
+
two=$(echo "$full" | grep -m1 . | cut -c-2)
# Make sure full splice has the same contents as a standard read.
- do_splice "$filename" 4096 "$full"
+ echo " splicing 4096 bytes ..." >&2
+ if ! do_splice "$filename" 4096 "$full" "full read" ; then
+ return 1
+ fi
# Make sure a partial splice see the first two characters.
- do_splice "$filename" 2 "$two"
+ echo " splicing 2 bytes ..." >&2
+ if ! do_splice "$filename" 2 "$two" "'$two'" ; then
+ return 1
+ fi
+
+ return 0
}
-# proc_single_open(), seq_read()
-test_splice /proc/$$/limits
-# special open, seq_read()
-test_splice /proc/$$/comm
+### /proc/$pid/ has no splice interface; these should all fail.
+expect_failure "proc_single_open(), seq_read() splice" test_splice /proc/$$/limits
+expect_failure "special open(), seq_read() splice" test_splice /proc/$$/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
+### /proc/sys/ has a splice interface; these should all succeed.
+expect_success "proc_handler: proc_dointvec_minmax() splice" test_splice /proc/sys/fs/nr_open
+expect_success "proc_handler: proc_dostring() splice" test_splice /proc/sys/kernel/modprobe
+expect_success "proc_handler: special read splice" test_splice /proc/sys/kernel/version
+### /sys/ has no splice interface; these should all fail.
if ! [ -d /sys/module/test_module/sections ] ; then
- modprobe test_module
+ expect_success "test_module kernel module load" modprobe test_module
fi
-# kernfs, attr
-test_splice /sys/module/test_module/coresize
-# kernfs, binattr
-test_splice /sys/module/test_module/sections/.init.text
+expect_failure "kernfs attr splice" test_splice /sys/module/test_module/coresize
+expect_failure "kernfs binattr splice" test_splice /sys/module/test_module/sections/.init.text
exit $ret
--
2.30.2
