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>
This commit is contained in:
Kees Cook 2020-08-06 23:01:09 -07:00
parent 11990a5bd7
commit 9af47666cb
6 changed files with 118 additions and 2 deletions

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# SPDX-License-Identifier: GPL-2.0-only
default_file_splice_read
splice_read

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# SPDX-License-Identifier: GPL-2.0
TEST_PROGS := default_file_splice_read.sh
TEST_GEN_PROGS_EXTENDED := default_file_splice_read
TEST_PROGS := default_file_splice_read.sh short_splice_read.sh
TEST_GEN_PROGS_EXTENDED := default_file_splice_read splice_read
include ../lib.mk

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CONFIG_TEST_LKM=m

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timeout=5

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#!/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

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// SPDX-License-Identifier: GPL-2.0
#define _GNU_SOURCE
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
int main(int argc, char *argv[])
{
int fd;
size_t size;
ssize_t spliced;
if (argc < 2) {
fprintf(stderr, "Usage: %s INPUT [BYTES]\n", argv[0]);
return EXIT_FAILURE;
}
fd = open(argv[1], O_RDONLY);
if (fd < 0) {
perror(argv[1]);
return EXIT_FAILURE;
}
if (argc == 3)
size = atol(argv[2]);
else {
struct stat statbuf;
if (fstat(fd, &statbuf) < 0) {
perror(argv[1]);
return EXIT_FAILURE;
}
if (statbuf.st_size > INT_MAX) {
fprintf(stderr, "%s: Too big\n", argv[1]);
return EXIT_FAILURE;
}
size = statbuf.st_size;
}
/* splice(2) file to stdout. */
spliced = splice(fd, NULL, STDOUT_FILENO, NULL,
size, SPLICE_F_MOVE);
if (spliced < 0) {
perror("splice");
return EXIT_FAILURE;
}
close(fd);
return EXIT_SUCCESS;
}