Unverified Commit 6da752f5 authored by David Disseldorp's avatar David Disseldorp Committed by Nathan Chancellor
Browse files

initramfs_test: add filename padding test case 



Confirm that cpio filenames with multiple trailing zeros (accounted for
in namesize) extract successfully.

Signed-off-by: default avatarDavid Disseldorp <ddiss@suse.de>
Acked-by: default avatarNicolas Schier <nsc@kernel.org>
Link: https://lore.kernel.org/r/20250819032607.28727-9-ddiss@suse.de
[nathan: Fix duplicate filesize initialization, reported at
         https://lore.kernel.org/202508200304.wF1u78il-lkp@intel.com/

]
Signed-off-by: default avatarNathan Chancellor <nathan@kernel.org>
parent 5467e855

init/initramfs_test.c

+66 −1
Original line number Diff line number Diff line
@@ -45,8 +45,11 @@ static size_t fill_cpio(struct initramfs_test_cpio *cs, size_t csz, char *out) 
			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;

		if (thislen != CPIO_HDRLEN + c->namesize)

			pr_debug("padded to: %u\n", CPIO_HDRLEN + c->namesize);

		off += CPIO_HDRLEN + c->namesize;

		while (off & 3)

			out[off++] = '\0';
@@ -383,6 +386,67 @@ static void __init initramfs_test_many(struct kunit *test) 
	kfree(cpio_srcbuf);

}



/*

 * An initramfs filename is namesize in length, including the zero-terminator.

 * A filename can be zero-terminated prior to namesize, with the remainder used

 * as padding. This can be useful for e.g. alignment of file data segments with

 * a 4KB filesystem block, allowing for extent sharing (reflinks) between cpio

 * source and destination. This hack works with both GNU cpio and initramfs, as

 * long as PATH_MAX isn't exceeded.

 */

static void __init initramfs_test_fname_pad(struct kunit *test)

{

	char *err;

	size_t len;

	struct file *file;

	char fdata[] = "this file data is aligned at 4K in the archive";

	struct test_fname_pad {

		char padded_fname[4096 - CPIO_HDRLEN];

		char cpio_srcbuf[CPIO_HDRLEN + PATH_MAX + 3 + sizeof(fdata)];

	} *tbufs = kzalloc(sizeof(struct test_fname_pad), GFP_KERNEL);

	struct initramfs_test_cpio c[] = { {

		.magic = "070701",

		.ino = 1,

		.mode = S_IFREG | 0777,

		.uid = 0,

		.gid = 0,

		.nlink = 1,

		.mtime = 1,

		.filesize = sizeof(fdata),

		.devmajor = 0,

		.devminor = 1,

		.rdevmajor = 0,

		.rdevminor = 0,

		/* align file data at 4K archive offset via padded fname */

		.namesize = 4096 - CPIO_HDRLEN,

		.csum = 0,

		.fname = tbufs->padded_fname,

		.data = fdata,

	} };



	memcpy(tbufs->padded_fname, "padded_fname", sizeof("padded_fname"));

	len = fill_cpio(c, ARRAY_SIZE(c), tbufs->cpio_srcbuf);



	err = unpack_to_rootfs(tbufs->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, tbufs->cpio_srcbuf, c[0].filesize, NULL);

	KUNIT_EXPECT_EQ(test, len, c[0].filesize);

	KUNIT_EXPECT_MEMEQ(test, tbufs->cpio_srcbuf, c[0].data, len);



	fput(file);

	KUNIT_EXPECT_EQ(test, init_unlink(c[0].fname), 0);

out:

	kfree(tbufs);

}



/*

 * The kunit_case/_suite struct cannot be marked as __initdata as this will be

 * used in debugfs to retrieve results after test has run.
@@ -394,6 +458,7 @@ static struct kunit_case __refdata initramfs_test_cases[] = { 
	KUNIT_CASE(initramfs_test_csum),

	KUNIT_CASE(initramfs_test_hardlink),

	KUNIT_CASE(initramfs_test_many),

	KUNIT_CASE(initramfs_test_fname_pad),

	{},

};