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Message-Id: <1516850875-25066-8-git-send-email-takondra@cisco.com>
Date: Thu, 25 Jan 2018 03:27:47 +0000
From: Taras Kondratiuk <takondra@...co.com>
To: "H. Peter Anvin" <hpa@...or.com>,
Al Viro <viro@...iv.linux.org.uk>,
Arnd Bergmann <arnd@...db.de>, Rob Landley <rob@...dley.net>,
Mimi Zohar <zohar@...ux.vnet.ibm.com>,
Jonathan Corbet <corbet@....net>,
James McMechan <james.w.mcmechan@...il.com>
Cc: initramfs@...r.kernel.org, Victor Kamensky <kamensky@...co.com>,
linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-security-module@...r.kernel.org, xe-linux-external@...co.com
Subject: [PATCH v2 07/15] initramfs: split header layout information from parsing function
Header parsing has hardcoded assumption about header field size and
layout. It is hard to modify the function to parse a new format.
Move information about size and layout into a data structure to
make parsing code more generic and simplify adding a new format.
This also removes some magic numbers.
Signed-off-by: Taras Kondratiuk <takondra@...co.com>
---
init/initramfs.c | 122 +++++++++++++++++++++++++++++++++++++++++--------------
1 file changed, 92 insertions(+), 30 deletions(-)
diff --git a/init/initramfs.c b/init/initramfs.c
index b3d39c8793be..7f0bbfde94e3 100644
--- a/init/initramfs.c
+++ b/init/initramfs.c
@@ -150,39 +150,100 @@ static void __init dir_utime(void)
}
}
-static __initdata time64_t mtime;
-
/* cpio header parsing */
-
-static __initdata unsigned long ino, major, minor, nlink;
+static __initdata time64_t mtime;
+static __initdata u32 ino, major, minor, nlink, rmajor, rminor;
static __initdata umode_t mode;
-static __initdata unsigned long body_len, name_len;
+static __initdata u32 body_len, name_len;
static __initdata uid_t uid;
static __initdata gid_t gid;
-static __initdata unsigned rdev;
+static __initdata u32 mode_u32;
+
+struct cpio_hdr_field {
+ size_t offset;
+ size_t size;
+ void *out;
+ size_t out_size;
+ const char *name;
+};
+
+#define HDR_FIELD(type, field, variable) \
+ { .offset = offsetof(type, field) + \
+ BUILD_BUG_ON_ZERO(sizeof(*(variable))*2 < FIELD_SIZEOF(type, field)),\
+ .size = FIELD_SIZEOF(type, field), \
+ .out = variable, \
+ .out_size = sizeof(*(variable)), \
+ .name = #field }
+
+#define NEWC_FIELD(field, variable) \
+ HDR_FIELD(struct cpio_newc_header, field, variable)
+
+#define CPIO_MAX_HEADER_SIZE sizeof(struct cpio_newc_header)
+#define CPIO_MAX_FIELD_SIZE 8
+#define CPIO_MAGIC_SIZE 6
+
+struct cpio_newc_header {
+ char c_ino[8];
+ char c_mode[8];
+ char c_uid[8];
+ char c_gid[8];
+ char c_nlink[8];
+ char c_mtime[8];
+ char c_filesize[8];
+ char c_devmajor[8];
+ char c_devminor[8];
+ char c_rdevmajor[8];
+ char c_rdevminor[8];
+ char c_namesize[8];
+ char c_check[8];
+};
+
+static struct cpio_hdr_field cpio_newc_header_info[] __initdata = {
+ NEWC_FIELD(c_ino, &ino),
+ NEWC_FIELD(c_mode, &mode_u32),
+ NEWC_FIELD(c_uid, &uid),
+ NEWC_FIELD(c_gid, &gid),
+ NEWC_FIELD(c_nlink, &nlink),
+ NEWC_FIELD(c_mtime, &mtime),
+ NEWC_FIELD(c_filesize, &body_len),
+ NEWC_FIELD(c_devmajor, &major),
+ NEWC_FIELD(c_devminor, &minor),
+ NEWC_FIELD(c_rdevmajor, &rmajor),
+ NEWC_FIELD(c_rdevminor, &rminor),
+ NEWC_FIELD(c_namesize, &name_len),
+ { 0 },
+};
static void __init parse_header(char *s)
{
- unsigned long parsed[12];
- char buf[9];
- int i;
-
- buf[8] = '\0';
- for (i = 0; i < 12; i++, s += 8) {
- memcpy(buf, s, 8);
- parsed[i] = simple_strtoul(buf, NULL, 16);
+ char buf[CPIO_MAX_FIELD_SIZE + 1];
+ struct cpio_hdr_field *field = cpio_newc_header_info;
+
+ while (field->size) {
+ int ret = 0;
+
+ memcpy(buf, s + field->offset, field->size);
+ buf[field->size] = '\0';
+ switch (field->out_size) {
+ case sizeof(u32):
+ ret = kstrtou32(buf, 16, field->out);
+ pr_debug("cpio field %s: %u, buf: %s\n",
+ field->name, *(u32 *)field->out, buf);
+ break;
+ case sizeof(u64):
+ ret = kstrtou64(buf, 16, field->out);
+ pr_debug("cpio field %s: %llu, buf: %s\n",
+ field->name, *(u64 *)field->out, buf);
+ break;
+ default:
+ BUG_ON(1);
+ }
+
+ if (ret)
+ pr_err("invalid cpio header field (%d)", ret);
+ field++;
}
- 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];
+ mode = mode_u32;
}
/* FSM */
@@ -234,7 +295,7 @@ static __initdata char *header_buf, *symlink_buf, *name_buf;
static int __init do_start(void)
{
- read_into(header_buf, 6, do_format);
+ read_into(header_buf, CPIO_MAGIC_SIZE, do_format);
return 0;
}
@@ -254,15 +315,15 @@ static int __init do_collect(void)
static int __init do_format(void)
{
- if (memcmp(collected, "070707", 6)==0) {
+ if (memcmp(collected, "070707", CPIO_MAGIC_SIZE) == 0) {
error("incorrect cpio method used: use -H newc option");
return 1;
}
- if (memcmp(collected, "070701", 6)) {
+ if (memcmp(collected, "070701", CPIO_MAGIC_SIZE)) {
error("no cpio magic");
return 1;
}
- read_into(header_buf, 104, do_header);
+ read_into(header_buf, sizeof(struct cpio_newc_header), do_header);
return 0;
}
@@ -374,6 +435,7 @@ static int __init do_create(void)
} else if (S_ISBLK(mode) || S_ISCHR(mode) ||
S_ISFIFO(mode) || S_ISSOCK(mode)) {
if (maybe_link(name_buf) == 0) {
+ u32 rdev = new_encode_dev(MKDEV(rmajor, rminor));
sys_mknod(name_buf, mode, rdev);
sys_chown(name_buf, uid, gid);
sys_chmod(name_buf, mode);
@@ -464,7 +526,7 @@ static char * __init unpack_to_rootfs(char *buf, unsigned long len)
const char *compress_name;
static __initdata char msg_buf[64];
- header_buf = kmalloc(104, GFP_KERNEL);
+ header_buf = kmalloc(CPIO_MAX_HEADER_SIZE, GFP_KERNEL);
symlink_buf = kmalloc(PATH_MAX + 1, GFP_KERNEL);
name_buf = kmalloc(N_ALIGN(PATH_MAX), GFP_KERNEL);
--
2.10.3.dirty
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