Commit 800c24dc authored by David Disseldorp's avatar David Disseldorp Committed by Andrew Morton
Browse files

initramfs: support cpio extraction with file checksums 

Add support for extraction of checksum-enabled "070702" cpio archives,
specified in Documentation/driver-api/early-userspace/buffer-format.rst. 
Fail extraction if the calculated file data checksum doesn't match the
value carried in the header.

Link: https://lkml.kernel.org/r/20220404093429.27570-7-ddiss@suse.de


Signed-off-by: default avatarDavid Disseldorp <ddiss@suse.de>
Suggested-by: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Martin Wilck <mwilck@suse.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent ea804871

init/initramfs.c

+24 −5
Original line number Diff line number Diff line
@@ -17,8 +17,11 @@ 
#include <linux/init_syscalls.h>

#include <linux/umh.h>



static ssize_t __init xwrite(struct file *file, const char *p, size_t count,

		loff_t *pos)

static __initdata bool csum_present;

static __initdata u32 io_csum;



static ssize_t __init xwrite(struct file *file, const unsigned char *p,

		size_t count, loff_t *pos)

{

	ssize_t out = 0;
@@ -33,6 +36,13 @@ static ssize_t __init xwrite(struct file *file, const char *p, size_t count, 
		} else if (rv == 0)

			break;



		if (csum_present) {

			ssize_t i;



			for (i = 0; i < rv; i++)

				io_csum += p[i];

		}



		p += rv;

		out += rv;

		count -= rv;
@@ -176,15 +186,16 @@ static __initdata unsigned long body_len, name_len; 
static __initdata uid_t uid;

static __initdata gid_t gid;

static __initdata unsigned rdev;

static __initdata u32 hdr_csum;



static void __init parse_header(char *s)

{

	unsigned long parsed[12];

	unsigned long parsed[13];

	char buf[9];

	int i;



	buf[8] = '\0';

	for (i = 0, s += 6; i < 12; i++, s += 8) {

	for (i = 0, s += 6; i < 13; i++, s += 8) {

		memcpy(buf, s, 8);

		parsed[i] = simple_strtoul(buf, NULL, 16);

	}
@@ -199,6 +210,7 @@ static void __init parse_header(char *s) 
	minor = parsed[8];

	rdev = new_encode_dev(MKDEV(parsed[9], parsed[10]));

	name_len = parsed[11];

	hdr_csum = parsed[12];

}



/* FSM */
@@ -267,7 +279,11 @@ static int __init do_collect(void) 


static int __init do_header(void)

{

	if (memcmp(collected, "070701", 6)) {

	if (!memcmp(collected, "070701", 6)) {

		csum_present = false;

	} else if (!memcmp(collected, "070702", 6)) {

		csum_present = true;

	} else {

		if (memcmp(collected, "070707", 6) == 0)

			error("incorrect cpio method used: use -H newc option");

		else
@@ -362,6 +378,7 @@ static int __init do_name(void) 
			if (IS_ERR(wfile))

				return 0;

			wfile_pos = 0;

			io_csum = 0;



			vfs_fchown(wfile, uid, gid);

			vfs_fchmod(wfile, mode);
@@ -394,6 +411,8 @@ static int __init do_copy(void) 


		do_utime_path(&wfile->f_path, mtime);

		fput(wfile);

		if (csum_present && io_csum != hdr_csum)

			error("bad data checksum");

		eat(body_len);

		state = SkipIt;

		return 0;