From: Mimi Zohar <[email protected]>
This patch adds metadata to a file from a supplied buffer. The buffer might
contains multiple metadata records. The format of each record is:
<metadata len (ASCII, 8 chars)><version><type><metadata>
For now, only the TYPE_XATTR metadata type is supported. The specific
format of this metadata type is:
<xattr #N name>\0<xattr #N value>
[kamensky: fixed restoring of xattrs for symbolic links by using
sys_lsetxattr() instead of sys_setxattr()]
[sassu: removed state management, kept only do_setxattrs(), added support
for generic file metadata, replaced sys_lsetxattr() with
vfs_setxattr(), added check for entry_size, added check for
hdr->c_size, replaced strlen() with strnlen(); moved do_setxattrs()
before do_name()]
[zhangguangzhi: fix checkpatch warning EMBEDDED_FILENAME in
include/linux/initramfs.h]
Signed-off-by: Mimi Zohar <[email protected]>
Signed-off-by: Victor Kamensky <[email protected]>
Signed-off-by: Taras Kondratiuk <[email protected]>
Signed-off-by: Roberto Sassu <[email protected]>
Signed-off-by: Tianxing Zhang <[email protected]>
Reviewed-by: Jason Yan <[email protected]>
Signed-off-by: Zheng Zengkai <[email protected]>
Signed-off-by: zhoushuiqing <[email protected]>
Signed-off-by: zhangguangzhi <[email protected]>
Signed-off-by: Danny Hu <[email protected]>
---
Changes in v6:
- Document lack of support for POSIX ACL restoration. The main use case is to
restore security.ima xattr for IMA use. POSIX ACL support is out of scope
for this patchset
- Check xattr name and value lengths to ensure they are valid and do not
exceed the limit
- Compare metadata header and record sizes against the remaining buffer
length to avoid pointer arithmetic overflow in bounds checks
- Use the kernel u32 type instead of uint32_t
Changes in v5:
- For debug print in do_setxattrs(), use print_hex_dump_debug() rather
than printing the xattr value as a string
- Use u32 metadata record lengths and reject records smaller than their
header
include/linux/initramfs.h | 19 +++++++
init/initramfs.c | 103 +++++++++++++++++++++++++++++++++++++-
2 files changed, 121 insertions(+), 1 deletion(-)
create mode 100644 include/linux/initramfs.h
diff --git a/include/linux/initramfs.h b/include/linux/initramfs.h
new file mode 100644
index 000000000000..9b3839dc88a1
--- /dev/null
+++ b/include/linux/initramfs.h
@@ -0,0 +1,19 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Include file for file metadata in the initial ram disk.
+ */
+#ifndef _LINUX_INITRAMFS_H
+#define _LINUX_INITRAMFS_H
+
+#define METADATA_FILENAME "METADATA!!!"
+
+enum metadata_types { TYPE_NONE, TYPE_XATTR, TYPE__LAST };
+
+struct metadata_hdr {
+ char c_size[8]; /* total size including c_size field */
+ char c_version; /* header version */
+ char c_type; /* metadata type */
+ char c_metadata[]; /* metadata */
+} __packed;
+
+#endif /*LINUX_INITRAMFS_H*/
diff --git a/init/initramfs.c b/init/initramfs.c
index ebddde9c8f0d..d206624d1160 100644
--- a/init/initramfs.c
+++ b/init/initramfs.c
@@ -10,7 +10,9 @@
#include <linux/hex.h>
#include <linux/init.h>
#include <linux/init_syscalls.h>
+#include <linux/initramfs.h>
#include <linux/kstrtox.h>
+#include <linux/limits.h>
#include <linux/memblock.h>
#include <linux/mm.h>
#include <linux/namei.h>
@@ -22,6 +24,7 @@
#include <linux/types.h>
#include <linux/umh.h>
#include <linux/utime.h>
+#include <linux/xattr.h>
#include <asm/byteorder.h>
@@ -189,7 +192,7 @@ static __initdata time64_t mtime;
static __initdata unsigned long ino, major, minor, nlink;
static __initdata umode_t mode;
-static __initdata unsigned long body_len, name_len;
+static __initdata unsigned long body_len, name_len, metadata_len;
static __initdata uid_t uid;
static __initdata gid_t gid;
static __initdata unsigned rdev;
@@ -264,6 +267,7 @@ static void __init read_into(char *buf, unsigned size, enum
state next)
}
static __initdata char *header_buf, *symlink_buf, *name_buf;
+static __initdata char *metadata_buf;
static int __init do_start(void)
{
@@ -365,6 +369,103 @@ static int __init maybe_link(void)
return 0;
}
+static int __init do_setxattrs(char *pathname, char *buf, size_t size)
+{
+ struct path path;
+ char *xattr_name, *xattr_value;
+ u32 xattr_name_size, xattr_value_size;
+ int ret;
+
+ xattr_name = buf;
+ xattr_name_size = strnlen(xattr_name, size);
+ if (xattr_name_size == size) {
+ error("malformed xattrs");
+ return -EINVAL;
+ }
+
+ if (!xattr_name_size || xattr_name_size > XATTR_NAME_MAX) {
+ error("invalid xattr name length");
+ return -EINVAL;
+ }
+
+ xattr_value = xattr_name + xattr_name_size + 1;
+ xattr_value_size = buf + size - xattr_value;
+ if (xattr_value_size > XATTR_SIZE_MAX) {
+ error("xattr value exceeds size limit");
+ return -EINVAL;
+ }
+
+ ret = kern_path(pathname, 0, &path);
+ if (!ret) {
+ /*
+ * POSIX ACL restoration is currently unsupported.
+ * vfs_setxattr() rejects POSIX ACL xattrs with -EOPNOTSUPP.
+ */
+ ret = vfs_setxattr(&nop_mnt_idmap, path.dentry, xattr_name,
xattr_value,
+ xattr_value_size, 0);
+
+ path_put(&path);
+ }
+
+ pr_debug("%s: %s size: %u (ret: %d)\n", pathname, xattr_name,
+ xattr_value_size, ret);
+ print_hex_dump_debug("xattr value: ", DUMP_PREFIX_OFFSET,
+ 16, 1, xattr_value, xattr_value_size, false);
+
+ return ret;
+}
+
+static int __init __maybe_unused do_parse_metadata(char *pathname)
+{
+ char *buf = metadata_buf;
+ char *bufend = metadata_buf + metadata_len;
+ struct metadata_hdr *hdr;
+ char str[sizeof(hdr->c_size) + 1];
+ u32 entry_size;
+
+ if (!metadata_len)
+ return 0;
+
+ str[sizeof(hdr->c_size)] = 0;
+
+ while (buf < bufend) {
+ int ret;
+
+ if (bufend - buf < sizeof(*hdr)) {
+ error("malformed metadata");
+ break;
+ }
+
+ hdr = (struct metadata_hdr *)buf;
+ if (hdr->c_version != 1) {
+ pr_debug("Unsupported header version\n");
+ break;
+ }
+
+ memcpy(str, hdr->c_size, sizeof(hdr->c_size));
+ ret = kstrtou32(str, 16, &entry_size);
+ if (ret || entry_size < sizeof(*hdr) ||
+ entry_size > bufend - buf) {
+ error("malformed xattrs");
+ break;
+ }
+
+ switch (hdr->c_type) {
+ case TYPE_XATTR:
+ do_setxattrs(pathname, buf + sizeof(*hdr),
+ entry_size - sizeof(*hdr));
+ break;
+ default:
+ pr_debug("Unsupported metadata type\n");
+ break;
+ }
+
+ buf += entry_size;
+ }
+
+ return 0;
+}
+
static __initdata struct file *wfile;
static __initdata loff_t wfile_pos;
--
2.51.0
