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initramfs_test: kunit tests for initramfs unpacking

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Provide some basic initramfs unpack sanity tests covering:

- simple file / dir extraction
- filename field overrun, as reported and fixed separately via
  https://lore.kernel.org/r/20241030035509.20194-2-ddiss@suse.de
- "070702" cpio data checksums
- hardlinks

Signed-off-by: David Disseldorp <ddiss@suse.de>
Link: https://lore.kernel.org/r/20250304061020.9815-3-ddiss@suse.de
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
David Disseldorp 2025-03-04 16:57:45 +11:00 committed by Christian Brauner
parent 5f469c4f71
commit 83c0b27266
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4 changed files with 418 additions and 0 deletions
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3
init/.kunitconfig Normal file
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@ -0,0 +1,3 @@
CONFIG_KUNIT=y
CONFIG_BLK_DEV_INITRD=y
CONFIG_INITRAMFS_TEST=y

7
init/Kconfig
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@ -1454,6 +1454,13 @@ config INITRAMFS_PRESERVE_MTIME
If unsure, say Y.
config INITRAMFS_TEST
bool "Test initramfs cpio archive extraction" if !KUNIT_ALL_TESTS
depends on BLK_DEV_INITRD && KUNIT=y
default KUNIT_ALL_TESTS
help
Build KUnit tests for initramfs. See Documentation/dev-tools/kunit
choice
prompt "Compiler optimization level"
default CC_OPTIMIZE_FOR_PERFORMANCE

1
init/Makefile
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@ -12,6 +12,7 @@ else
obj-$(CONFIG_BLK_DEV_INITRD) += initramfs.o
endif
obj-$(CONFIG_GENERIC_CALIBRATE_DELAY) += calibrate.o
obj-$(CONFIG_INITRAMFS_TEST) += initramfs_test.o
obj-y += init_task.o

407
init/initramfs_test.c Normal file
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@ -0,0 +1,407 @@
// SPDX-License-Identifier: GPL-2.0
#include <kunit/test.h>
#include <linux/fcntl.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/init_syscalls.h>
#include <linux/stringify.h>
#include <linux/timekeeping.h>
#include "initramfs_internal.h"
struct initramfs_test_cpio {
char *magic;
unsigned int ino;
unsigned int mode;
unsigned int uid;
unsigned int gid;
unsigned int nlink;
unsigned int mtime;
unsigned int filesize;
unsigned int devmajor;
unsigned int devminor;
unsigned int rdevmajor;
unsigned int rdevminor;
unsigned int namesize;
unsigned int csum;
char *fname;
char *data;
};
static size_t fill_cpio(struct initramfs_test_cpio *cs, size_t csz, char *out)
{
int i;
size_t off = 0;
for (i = 0; i < csz; i++) {
char *pos = &out[off];
struct initramfs_test_cpio *c = &cs[i];
size_t thislen;
/* +1 to account for nulterm */
thislen = sprintf(pos, "%s"
"%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x"
"%s",
c->magic, c->ino, c->mode, c->uid, c->gid, c->nlink,
c->mtime, c->filesize, c->devmajor, c->devminor,
c->rdevmajor, c->rdevminor, c->namesize, c->csum,
c->fname) + 1;
pr_debug("packing (%zu): %.*s\n", thislen, (int)thislen, pos);
off += thislen;
while (off & 3)
out[off++] = '\0';
memcpy(&out[off], c->data, c->filesize);
off += c->filesize;
while (off & 3)
out[off++] = '\0';
}
return off;
}
static void __init initramfs_test_extract(struct kunit *test)
{
char *err, *cpio_srcbuf;
size_t len;
struct timespec64 ts_before, ts_after;
struct kstat st = {};
struct initramfs_test_cpio c[] = { {
.magic = "070701",
.ino = 1,
.mode = S_IFREG | 0777,
.uid = 12,
.gid = 34,
.nlink = 1,
.mtime = 56,
.filesize = 0,
.devmajor = 0,
.devminor = 1,
.rdevmajor = 0,
.rdevminor = 0,
.namesize = sizeof("initramfs_test_extract"),
.csum = 0,
.fname = "initramfs_test_extract",
}, {
.magic = "070701",
.ino = 2,
.mode = S_IFDIR | 0777,
.nlink = 1,
.mtime = 57,
.devminor = 1,
.namesize = sizeof("initramfs_test_extract_dir"),
.fname = "initramfs_test_extract_dir",
}, {
.magic = "070701",
.namesize = sizeof("TRAILER!!!"),
.fname = "TRAILER!!!",
} };
/* +3 to cater for any 4-byte end-alignment */
cpio_srcbuf = kzalloc(ARRAY_SIZE(c) * (CPIO_HDRLEN + PATH_MAX + 3),
GFP_KERNEL);
len = fill_cpio(c, ARRAY_SIZE(c), cpio_srcbuf);
ktime_get_real_ts64(&ts_before);
err = unpack_to_rootfs(cpio_srcbuf, len);
ktime_get_real_ts64(&ts_after);
if (err) {
KUNIT_FAIL(test, "unpack failed %s", err);
goto out;
}
KUNIT_EXPECT_EQ(test, init_stat(c[0].fname, &st, 0), 0);
KUNIT_EXPECT_TRUE(test, S_ISREG(st.mode));
KUNIT_EXPECT_TRUE(test, uid_eq(st.uid, KUIDT_INIT(c[0].uid)));
KUNIT_EXPECT_TRUE(test, gid_eq(st.gid, KGIDT_INIT(c[0].gid)));
KUNIT_EXPECT_EQ(test, st.nlink, 1);
if (IS_ENABLED(CONFIG_INITRAMFS_PRESERVE_MTIME)) {
KUNIT_EXPECT_EQ(test, st.mtime.tv_sec, c[0].mtime);
} else {
KUNIT_EXPECT_GE(test, st.mtime.tv_sec, ts_before.tv_sec);
KUNIT_EXPECT_LE(test, st.mtime.tv_sec, ts_after.tv_sec);
}
KUNIT_EXPECT_EQ(test, st.blocks, c[0].filesize);
KUNIT_EXPECT_EQ(test, init_stat(c[1].fname, &st, 0), 0);
KUNIT_EXPECT_TRUE(test, S_ISDIR(st.mode));
if (IS_ENABLED(CONFIG_INITRAMFS_PRESERVE_MTIME)) {
KUNIT_EXPECT_EQ(test, st.mtime.tv_sec, c[1].mtime);
} else {
KUNIT_EXPECT_GE(test, st.mtime.tv_sec, ts_before.tv_sec);
KUNIT_EXPECT_LE(test, st.mtime.tv_sec, ts_after.tv_sec);
}
KUNIT_EXPECT_EQ(test, init_unlink(c[0].fname), 0);
KUNIT_EXPECT_EQ(test, init_rmdir(c[1].fname), 0);
out:
kfree(cpio_srcbuf);
}
/*
* Don't terminate filename. Previously, the cpio filename field was passed
* directly to filp_open(collected, O_CREAT|..) without nulterm checks. See
* https://lore.kernel.org/linux-fsdevel/20241030035509.20194-2-ddiss@suse.de
*/
static void __init initramfs_test_fname_overrun(struct kunit *test)
{
char *err, *cpio_srcbuf;
size_t len, suffix_off;
struct initramfs_test_cpio c[] = { {
.magic = "070701",
.ino = 1,
.mode = S_IFREG | 0777,
.uid = 0,
.gid = 0,
.nlink = 1,
.mtime = 1,
.filesize = 0,
.devmajor = 0,
.devminor = 1,
.rdevmajor = 0,
.rdevminor = 0,
.namesize = sizeof("initramfs_test_fname_overrun"),
.csum = 0,
.fname = "initramfs_test_fname_overrun",
} };
/*
* poison cpio source buffer, so we can detect overrun. source
* buffer is used by read_into() when hdr or fname
* are already available (e.g. no compression).
*/
cpio_srcbuf = kmalloc(CPIO_HDRLEN + PATH_MAX + 3, GFP_KERNEL);
memset(cpio_srcbuf, 'B', CPIO_HDRLEN + PATH_MAX + 3);
/* limit overrun to avoid crashes / filp_open() ENAMETOOLONG */
cpio_srcbuf[CPIO_HDRLEN + strlen(c[0].fname) + 20] = '\0';
len = fill_cpio(c, ARRAY_SIZE(c), cpio_srcbuf);
/* overwrite trailing fname terminator and padding */
suffix_off = len - 1;
while (cpio_srcbuf[suffix_off] == '\0') {
cpio_srcbuf[suffix_off] = 'P';
suffix_off--;
}
err = unpack_to_rootfs(cpio_srcbuf, len);
KUNIT_EXPECT_NOT_NULL(test, err);
kfree(cpio_srcbuf);
}
static void __init initramfs_test_data(struct kunit *test)
{
char *err, *cpio_srcbuf;
size_t len;
struct file *file;
struct initramfs_test_cpio c[] = { {
.magic = "070701",
.ino = 1,
.mode = S_IFREG | 0777,
.uid = 0,
.gid = 0,
.nlink = 1,
.mtime = 1,
.filesize = sizeof("ASDF") - 1,
.devmajor = 0,
.devminor = 1,
.rdevmajor = 0,
.rdevminor = 0,
.namesize = sizeof("initramfs_test_data"),
.csum = 0,
.fname = "initramfs_test_data",
.data = "ASDF",
} };
/* +6 for max name and data 4-byte padding */
cpio_srcbuf = kmalloc(CPIO_HDRLEN + c[0].namesize + c[0].filesize + 6,
GFP_KERNEL);
len = fill_cpio(c, ARRAY_SIZE(c), cpio_srcbuf);
err = unpack_to_rootfs(cpio_srcbuf, len);
KUNIT_EXPECT_NULL(test, err);
file = filp_open(c[0].fname, O_RDONLY, 0);
if (IS_ERR(file)) {
KUNIT_FAIL(test, "open failed");
goto out;
}
/* read back file contents into @cpio_srcbuf and confirm match */
len = kernel_read(file, cpio_srcbuf, c[0].filesize, NULL);
KUNIT_EXPECT_EQ(test, len, c[0].filesize);
KUNIT_EXPECT_MEMEQ(test, cpio_srcbuf, c[0].data, len);
fput(file);
KUNIT_EXPECT_EQ(test, init_unlink(c[0].fname), 0);
out:
kfree(cpio_srcbuf);
}
static void __init initramfs_test_csum(struct kunit *test)
{
char *err, *cpio_srcbuf;
size_t len;
struct initramfs_test_cpio c[] = { {
/* 070702 magic indicates a valid csum is present */
.magic = "070702",
.ino = 1,
.mode = S_IFREG | 0777,
.nlink = 1,
.filesize = sizeof("ASDF") - 1,
.devminor = 1,
.namesize = sizeof("initramfs_test_csum"),
.csum = 'A' + 'S' + 'D' + 'F',
.fname = "initramfs_test_csum",
.data = "ASDF",
}, {
/* mix csum entry above with no-csum entry below */
.magic = "070701",
.ino = 2,
.mode = S_IFREG | 0777,
.nlink = 1,
.filesize = sizeof("ASDF") - 1,
.devminor = 1,
.namesize = sizeof("initramfs_test_csum_not_here"),
/* csum ignored */
.csum = 5555,
.fname = "initramfs_test_csum_not_here",
.data = "ASDF",
} };
cpio_srcbuf = kmalloc(8192, GFP_KERNEL);
len = fill_cpio(c, ARRAY_SIZE(c), cpio_srcbuf);
err = unpack_to_rootfs(cpio_srcbuf, len);
KUNIT_EXPECT_NULL(test, err);
KUNIT_EXPECT_EQ(test, init_unlink(c[0].fname), 0);
KUNIT_EXPECT_EQ(test, init_unlink(c[1].fname), 0);
/* mess up the csum and confirm that unpack fails */
c[0].csum--;
len = fill_cpio(c, ARRAY_SIZE(c), cpio_srcbuf);
err = unpack_to_rootfs(cpio_srcbuf, len);
KUNIT_EXPECT_NOT_NULL(test, err);
/*
* file (with content) is still retained in case of bad-csum abort.
* Perhaps we should change this.
*/
KUNIT_EXPECT_EQ(test, init_unlink(c[0].fname), 0);
KUNIT_EXPECT_EQ(test, init_unlink(c[1].fname), -ENOENT);
kfree(cpio_srcbuf);
}
/*
* hardlink hashtable may leak when the archive omits a trailer:
* https://lore.kernel.org/r/20241107002044.16477-10-ddiss@suse.de/
*/
static void __init initramfs_test_hardlink(struct kunit *test)
{
char *err, *cpio_srcbuf;
size_t len;
struct kstat st0, st1;
struct initramfs_test_cpio c[] = { {
.magic = "070701",
.ino = 1,
.mode = S_IFREG | 0777,
.nlink = 2,
.devminor = 1,
.namesize = sizeof("initramfs_test_hardlink"),
.fname = "initramfs_test_hardlink",
}, {
/* hardlink data is present in last archive entry */
.magic = "070701",
.ino = 1,
.mode = S_IFREG | 0777,
.nlink = 2,
.filesize = sizeof("ASDF") - 1,
.devminor = 1,
.namesize = sizeof("initramfs_test_hardlink_link"),
.fname = "initramfs_test_hardlink_link",
.data = "ASDF",
} };
cpio_srcbuf = kmalloc(8192, GFP_KERNEL);
len = fill_cpio(c, ARRAY_SIZE(c), cpio_srcbuf);
err = unpack_to_rootfs(cpio_srcbuf, len);
KUNIT_EXPECT_NULL(test, err);
KUNIT_EXPECT_EQ(test, init_stat(c[0].fname, &st0, 0), 0);
KUNIT_EXPECT_EQ(test, init_stat(c[1].fname, &st1, 0), 0);
KUNIT_EXPECT_EQ(test, st0.ino, st1.ino);
KUNIT_EXPECT_EQ(test, st0.nlink, 2);
KUNIT_EXPECT_EQ(test, st1.nlink, 2);
KUNIT_EXPECT_EQ(test, init_unlink(c[0].fname), 0);
KUNIT_EXPECT_EQ(test, init_unlink(c[1].fname), 0);
kfree(cpio_srcbuf);
}
#define INITRAMFS_TEST_MANY_LIMIT 1000
#define INITRAMFS_TEST_MANY_PATH_MAX (sizeof("initramfs_test_many-") \
+ sizeof(__stringify(INITRAMFS_TEST_MANY_LIMIT)))
static void __init initramfs_test_many(struct kunit *test)
{
char *err, *cpio_srcbuf, *p;
size_t len = INITRAMFS_TEST_MANY_LIMIT *
(CPIO_HDRLEN + INITRAMFS_TEST_MANY_PATH_MAX + 3);
char thispath[INITRAMFS_TEST_MANY_PATH_MAX];
int i;
p = cpio_srcbuf = kmalloc(len, GFP_KERNEL);
for (i = 0; i < INITRAMFS_TEST_MANY_LIMIT; i++) {
struct initramfs_test_cpio c = {
.magic = "070701",
.ino = i,
.mode = S_IFREG | 0777,
.nlink = 1,
.devminor = 1,
.fname = thispath,
};
c.namesize = 1 + sprintf(thispath, "initramfs_test_many-%d", i);
p += fill_cpio(&c, 1, p);
}
len = p - cpio_srcbuf;
err = unpack_to_rootfs(cpio_srcbuf, len);
KUNIT_EXPECT_NULL(test, err);
for (i = 0; i < INITRAMFS_TEST_MANY_LIMIT; i++) {
sprintf(thispath, "initramfs_test_many-%d", i);
KUNIT_EXPECT_EQ(test, init_unlink(thispath), 0);
}
kfree(cpio_srcbuf);
}
/*
* The kunit_case/_suite struct cannot be marked as __initdata as this will be
* used in debugfs to retrieve results after test has run.
*/
static struct kunit_case __refdata initramfs_test_cases[] = {
KUNIT_CASE(initramfs_test_extract),
KUNIT_CASE(initramfs_test_fname_overrun),
KUNIT_CASE(initramfs_test_data),
KUNIT_CASE(initramfs_test_csum),
KUNIT_CASE(initramfs_test_hardlink),
KUNIT_CASE(initramfs_test_many),
{},
};
static struct kunit_suite initramfs_test_suite = {
.name = "initramfs",
.test_cases = initramfs_test_cases,
};
kunit_test_init_section_suites(&initramfs_test_suite);
MODULE_DESCRIPTION("Initramfs KUnit test suite");
MODULE_LICENSE("GPL v2");