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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: David Disseldorp <ddiss@suse.de>
Suggested-by: Matthew 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: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
David Disseldorp 2022-05-09 18:29:20 -07:00 committed by akpm
parent ea8048719a
commit 800c24dc34
1 changed files with 24 additions and 5 deletions
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29
init/initramfs.c
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@ -17,8 +17,11 @@
#include <linux/init_syscalls.h> #include <linux/init_syscalls.h>
#include <linux/umh.h> #include <linux/umh.h>
static ssize_t __init xwrite(struct file *file, const char *p, size_t count, static __initdata bool csum_present;
loff_t *pos) 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; 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) } else if (rv == 0)
break; break;
if (csum_present) {
ssize_t i;
for (i = 0; i < rv; i++)
io_csum += p[i];
}
p += rv; p += rv;
out += rv; out += rv;
count -= rv; count -= rv;
@ -176,15 +186,16 @@ static __initdata unsigned long body_len, name_len;
static __initdata uid_t uid; static __initdata uid_t uid;
static __initdata gid_t gid; static __initdata gid_t gid;
static __initdata unsigned rdev; static __initdata unsigned rdev;
static __initdata u32 hdr_csum;
static void __init parse_header(char *s) static void __init parse_header(char *s)
{ {
unsigned long parsed[12]; unsigned long parsed[13];
char buf[9]; char buf[9];
int i; int i;
buf[8] = '\0'; 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); memcpy(buf, s, 8);
parsed[i] = simple_strtoul(buf, NULL, 16); parsed[i] = simple_strtoul(buf, NULL, 16);
} }
@ -199,6 +210,7 @@ static void __init parse_header(char *s)
minor = parsed[8]; minor = parsed[8];
rdev = new_encode_dev(MKDEV(parsed[9], parsed[10])); rdev = new_encode_dev(MKDEV(parsed[9], parsed[10]));
name_len = parsed[11]; name_len = parsed[11];
hdr_csum = parsed[12];
} }
/* FSM */ /* FSM */
@ -267,7 +279,11 @@ static int __init do_collect(void)
static int __init do_header(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) if (memcmp(collected, "070707", 6) == 0)
error("incorrect cpio method used: use -H newc option"); error("incorrect cpio method used: use -H newc option");
else else
@ -362,6 +378,7 @@ static int __init do_name(void)
if (IS_ERR(wfile)) if (IS_ERR(wfile))
return 0; return 0;
wfile_pos = 0; wfile_pos = 0;
io_csum = 0;
vfs_fchown(wfile, uid, gid); vfs_fchown(wfile, uid, gid);
vfs_fchmod(wfile, mode); vfs_fchmod(wfile, mode);
@ -394,6 +411,8 @@ static int __init do_copy(void)
do_utime_path(&wfile->f_path, mtime); do_utime_path(&wfile->f_path, mtime);
fput(wfile); fput(wfile);
if (csum_present && io_csum != hdr_csum)
error("bad data checksum");
eat(body_len); eat(body_len);
state = SkipIt; state = SkipIt;
return 0; return 0;