initramfs: Refactor to use hex2bin() instead of custom approach

There is a simple_strntoul() function used solely as a shortcut
for hex2bin() with proper endianess conversions. Replace that
and drop the unneeded function in the next changes.

This implementation will abort if we fail to parse the cpio header,
instead of using potentially bogus header values.

Co-developed-by: David Disseldorp <ddiss@suse.de>
Signed-off-by: David Disseldorp <ddiss@suse.de>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://patch.msgid.link/20260331070519.5974-5-ddiss@suse.de
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>

diff --git a/init/initramfs.c b/init/initramfs.c
index bf9664fdd8fe8145daf6c039b321e5ef2103c10d..20a18fcda48ee4b3b9fd7b7013711e9ab1e1956f 100644 (file)
--- a/init/initramfs.c
+++ b/init/initramfs.c
@@ -6,6 +6,7 @@
 #include <linux/fcntl.h>
 #include <linux/file.h>
 #include <linux/fs.h>
+#include <linux/hex.h>
 #include <linux/init.h>
 #include <linux/init_syscalls.h>
 #include <linux/kstrtox.h>
@@ -21,6 +22,8 @@
 #include <linux/umh.h>
 #include <linux/utime.h>
 
+#include <asm/byteorder.h>
+
 #include "do_mounts.h"
 #include "initramfs_internal.h"
 
@@ -190,26 +193,30 @@ static __initdata gid_t gid;
 static __initdata unsigned rdev;
 static __initdata u32 hdr_csum;
 
-static void __init parse_header(char *s)
+static int __init parse_header(char *s)
 {
-       unsigned long parsed[13];
-       int i;
+       __be32 header[13];
+       int ret;
 
-       for (i = 0, s += 6; i < 13; i++, s += 8)
-               parsed[i] = simple_strntoul(s, NULL, 16, 8);
+       ret = hex2bin((u8 *)header, s + 6, sizeof(header));
+       if (ret) {
+               error("damaged header");
+               return ret;
+       }
 
-       ino = parsed[0];
-       mode = parsed[1];
-       uid = parsed[2];
-       gid = parsed[3];
-       nlink = parsed[4];
-       mtime = parsed[5]; /* breaks in y2106 */
-       body_len = parsed[6];
-       major = parsed[7];
-       minor = parsed[8];
-       rdev = new_encode_dev(MKDEV(parsed[9], parsed[10]));
-       name_len = parsed[11];
-       hdr_csum = parsed[12];
+       ino = be32_to_cpu(header[0]);
+       mode = be32_to_cpu(header[1]);
+       uid = be32_to_cpu(header[2]);
+       gid = be32_to_cpu(header[3]);
+       nlink = be32_to_cpu(header[4]);
+       mtime = be32_to_cpu(header[5]); /* breaks in y2106 */
+       body_len = be32_to_cpu(header[6]);
+       major = be32_to_cpu(header[7]);
+       minor = be32_to_cpu(header[8]);
+       rdev = new_encode_dev(MKDEV(be32_to_cpu(header[9]), be32_to_cpu(header[10])));
+       name_len = be32_to_cpu(header[11]);
+       hdr_csum = be32_to_cpu(header[12]);
+       return 0;
 }
 
 /* Finite-state machine */
@@ -289,7 +296,8 @@ static int __init do_header(void)
                        error("no cpio magic");
                return 1;
        }
-       parse_header(collected);
+       if (parse_header(collected))
+               return 1;
        next_header = this_header + N_ALIGN(name_len) + body_len;
        next_header = (next_header + 3) & ~3;
        state = SkipIt;

diff --git a/init/initramfs_test.c b/init/initramfs_test.c
index b9f83dc194aa69cd54d4a6b52d70444ab298fc7d..8a0ddc2db2c083be546e0bedcd9f86378b3373ac 100644 (file)
--- a/init/initramfs_test.c
+++ b/init/initramfs_test.c
@@ -31,8 +31,8 @@ struct initramfs_test_cpio {
 #define CPIO_HDR_FMT "%s%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%s"
 /*
  * Bogus newc header with "0x" prefixes on the uid, gid, and namesize values.
- * parse_header()/simple_str[n]toul() accept this, contrary to the initramfs
- * specification.
+ * parse_header()/simple_str[n]toul() accepted this, contrary to the initramfs
+ * specification. hex2bin() now fails.
  */
 #define CPIO_HDR_OX_INJECT \
        "%s%08x%08x0x%06x0X%06x%08x%08x%08x%08x%08x%08x%08x0x%06x%08x%s"
@@ -508,8 +508,7 @@ static void __init initramfs_test_hdr_hex(struct kunit *test)
 {
        char *err;
        size_t len;
-       struct kstat st0 = {}, st1 = {};
-       char fdata[] = "this file data will be unpacked";
+       char fdata[] = "this file data will not be unpacked";
        struct initramfs_test_bufs {
                char cpio_src[(CPIO_HDRLEN + PATH_MAX + 3 + sizeof(fdata)) * 2];
        } *tbufs = kzalloc(sizeof(struct initramfs_test_bufs), GFP_KERNEL);
@@ -539,22 +538,7 @@ static void __init initramfs_test_hdr_hex(struct kunit *test)
        len = fill_cpio(c, ARRAY_SIZE(c), true, tbufs->cpio_src);
 
        err = unpack_to_rootfs(tbufs->cpio_src, 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_TRUE(test,
-               uid_eq(st0.uid, make_kuid(current_user_ns(), (uid_t)0x123456)));
-       KUNIT_EXPECT_TRUE(test,
-               gid_eq(st0.gid, make_kgid(current_user_ns(), (gid_t)0x123457)));
-       KUNIT_EXPECT_TRUE(test,
-               uid_eq(st1.uid, make_kuid(current_user_ns(), (uid_t)0x56)));
-       KUNIT_EXPECT_TRUE(test,
-               gid_eq(st1.gid, make_kgid(current_user_ns(), (gid_t)0x57)));
-
-       KUNIT_EXPECT_EQ(test, init_unlink(c[0].fname), 0);
-       KUNIT_EXPECT_EQ(test, init_rmdir(c[1].fname), 0);
+       KUNIT_EXPECT_NOT_NULL(test, err);
 
        kfree(tbufs);
 }