selftests/bpf: Test RENAME_EXCHANGE and RENAME_NOREPLACE on bpffs

Add tests to exercise the behaviour of RENAME_EXCHANGE and RENAME_NOREPLACE
on bpffs. The former checks that after an exchange the inode of two
directories has changed. The latter checks that the source still exists
after a failed rename. Generally, having support for renameat2(RENAME_EXCHANGE)
in bpffs fixes atomic upgrades of our sk_lookup control plane.

Signed-off-by: Lorenz Bauer <lmb@cloudflare.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20211028094724.59043-5-lmb@cloudflare.com
This commit is contained in:
Lorenz Bauer 2021-10-28 10:47:24 +01:00 committed by Daniel Borkmann
parent 9fc23c22e5
commit 7e5ad817ec
1 changed files with 64 additions and 1 deletions

View File

@ -1,6 +1,7 @@
// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2020 Facebook */
#define _GNU_SOURCE
#include <stdio.h>
#include <sched.h>
#include <sys/mount.h>
#include <sys/stat.h>
@ -29,7 +30,8 @@ static int read_iter(char *file)
static int fn(void)
{
int err;
struct stat a, b, c;
int err, map;
err = unshare(CLONE_NEWNS);
if (!ASSERT_OK(err, "unshare"))
@ -67,6 +69,67 @@ static int fn(void)
err = read_iter(TDIR "/fs2/progs.debug");
if (!ASSERT_OK(err, "reading " TDIR "/fs2/progs.debug"))
goto out;
err = mkdir(TDIR "/fs1/a", 0777);
if (!ASSERT_OK(err, "creating " TDIR "/fs1/a"))
goto out;
err = mkdir(TDIR "/fs1/a/1", 0777);
if (!ASSERT_OK(err, "creating " TDIR "/fs1/a/1"))
goto out;
err = mkdir(TDIR "/fs1/b", 0777);
if (!ASSERT_OK(err, "creating " TDIR "/fs1/b"))
goto out;
map = bpf_create_map(BPF_MAP_TYPE_ARRAY, 4, 4, 1, 0);
if (!ASSERT_GT(map, 0, "create_map(ARRAY)"))
goto out;
err = bpf_obj_pin(map, TDIR "/fs1/c");
if (!ASSERT_OK(err, "pin map"))
goto out;
close(map);
/* Check that RENAME_EXCHANGE works for directories. */
err = stat(TDIR "/fs1/a", &a);
if (!ASSERT_OK(err, "stat(" TDIR "/fs1/a)"))
goto out;
err = renameat2(0, TDIR "/fs1/a", 0, TDIR "/fs1/b", RENAME_EXCHANGE);
if (!ASSERT_OK(err, "renameat2(/fs1/a, /fs1/b, RENAME_EXCHANGE)"))
goto out;
err = stat(TDIR "/fs1/b", &b);
if (!ASSERT_OK(err, "stat(" TDIR "/fs1/b)"))
goto out;
if (!ASSERT_EQ(a.st_ino, b.st_ino, "b should have a's inode"))
goto out;
err = access(TDIR "/fs1/b/1", F_OK);
if (!ASSERT_OK(err, "access(" TDIR "/fs1/b/1)"))
goto out;
/* Check that RENAME_EXCHANGE works for mixed file types. */
err = stat(TDIR "/fs1/c", &c);
if (!ASSERT_OK(err, "stat(" TDIR "/fs1/map)"))
goto out;
err = renameat2(0, TDIR "/fs1/c", 0, TDIR "/fs1/b", RENAME_EXCHANGE);
if (!ASSERT_OK(err, "renameat2(/fs1/c, /fs1/b, RENAME_EXCHANGE)"))
goto out;
err = stat(TDIR "/fs1/b", &b);
if (!ASSERT_OK(err, "stat(" TDIR "/fs1/b)"))
goto out;
if (!ASSERT_EQ(c.st_ino, b.st_ino, "b should have c's inode"))
goto out;
err = access(TDIR "/fs1/c/1", F_OK);
if (!ASSERT_OK(err, "access(" TDIR "/fs1/c/1)"))
goto out;
/* Check that RENAME_NOREPLACE works. */
err = renameat2(0, TDIR "/fs1/b", 0, TDIR "/fs1/a", RENAME_NOREPLACE);
if (!ASSERT_ERR(err, "renameat2(RENAME_NOREPLACE)")) {
err = -EINVAL;
goto out;
}
err = access(TDIR "/fs1/b", F_OK);
if (!ASSERT_OK(err, "access(" TDIR "/fs1/b)"))
goto out;
out:
umount(TDIR "/fs1");
umount(TDIR "/fs2");