[v4,2/3] initramfs: read metadata from special file METADATA!!!
diff mbox series

Message ID 20190523121803.21638-3-roberto.sassu@huawei.com
State New
Headers show
Series
  • initramfs: add support for xattrs in the initial ram disk
Related show

Commit Message

Roberto Sassu May 23, 2019, 12:18 p.m. UTC
Instead of changing the CPIO format, metadata are parsed from regular files
with special name 'METADATA!!!'. This file immediately follows the file
metadata are added to.

This patch checks if the file being extracted has the special name and, if
yes, creates a buffer with the content of that file and calls
do_parse_metadata() to parse metadata from the buffer.

Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
Reported-by: kbuild test robot <lkp@intel.com>
---
 init/initramfs.c | 49 +++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 48 insertions(+), 1 deletion(-)

Comments

Mimi Zohar July 1, 2019, 12:54 p.m. UTC | #1
Hi Roberto,

> diff --git a/init/initramfs.c b/init/initramfs.c
> index 5de396a6aac0..862c03123de8 100644
> --- a/init/initramfs.c
> +++ b/init/initramfs.c

> +static int __init do_process_metadata(char *buf, int len, bool last)
> +{

Part of the problem in upstreaming CPIO xattr support has been the
difficulty in reading and understanding the initramfs code due to a
lack of comments.  At least for any new code, let's add some comments
to simplify the review.  In this case, understanding "last", before
reading the code, would help.

Mimi

> +	int ret = 0;
> +
> +	if (!metadata_buf) {
> +		metadata_buf_ptr = metadata_buf = kmalloc(body_len, GFP_KERNEL);
> +		if (!metadata_buf_ptr) {
> +			ret = -ENOMEM;
> +			goto out;
> +		}
> +
> +		metadata_len = body_len;
> +	}
> +
> +	if (metadata_buf_ptr + len > metadata_buf + metadata_len) {
> +		ret = -EINVAL;
> +		goto out;
> +	}
> +
> +	memcpy(metadata_buf_ptr, buf, len);
> +	metadata_buf_ptr += len;
> +
> +	if (last)
> +		do_parse_metadata(previous_name_buf);
> +out:
> +	if (ret < 0 || last) {
> +		kfree(metadata_buf);
> +		metadata_buf = NULL;
> +		metadata = 0;
> +	}
> +
> +	return ret;
> +}
> +
>  static int __init do_copy(void)
>  {
>  	if (byte_count >= body_len) {
>  		if (xwrite(wfd, victim, body_len) != body_len)
>  			error("write error");
> +		if (metadata)
> +			do_process_metadata(victim, body_len, true);
>  		ksys_close(wfd);
>  		do_utime(vcollected, mtime);
>  		kfree(vcollected);
> @@ -458,6 +500,8 @@ static int __init do_copy(void)
>  	} else {
>  		if (xwrite(wfd, victim, byte_count) != byte_count)
>  			error("write error");
> +		if (metadata)
> +			do_process_metadata(victim, byte_count, false);
>  		body_len -= byte_count;
>  		eat(byte_count);
>  		return 1;
>

Patch
diff mbox series

diff --git a/init/initramfs.c b/init/initramfs.c
index 5de396a6aac0..862c03123de8 100644
--- a/init/initramfs.c
+++ b/init/initramfs.c
@@ -222,6 +222,7 @@  static void __init read_into(char *buf, unsigned size, enum state next)
 }
 
 static __initdata char *header_buf, *symlink_buf, *name_buf, *metadata_buf;
+static __initdata char *metadata_buf_ptr, *previous_name_buf;
 
 static int __init do_start(void)
 {
@@ -400,6 +401,7 @@  static int __init __maybe_unused do_parse_metadata(char *pathname)
 }
 
 static __initdata int wfd;
+static __initdata int metadata;
 
 static int __init do_name(void)
 {
@@ -408,6 +410,10 @@  static int __init do_name(void)
 	if (strcmp(collected, "TRAILER!!!") == 0) {
 		free_hash();
 		return 0;
+	} else if (strcmp(collected, METADATA_FILENAME) == 0) {
+		metadata = 1;
+	} else {
+		memcpy(previous_name_buf, collected, strlen(collected) + 1);
 	}
 	clean_path(collected, mode);
 	if (S_ISREG(mode)) {
@@ -444,11 +450,47 @@  static int __init do_name(void)
 	return 0;
 }
 
+static int __init do_process_metadata(char *buf, int len, bool last)
+{
+	int ret = 0;
+
+	if (!metadata_buf) {
+		metadata_buf_ptr = metadata_buf = kmalloc(body_len, GFP_KERNEL);
+		if (!metadata_buf_ptr) {
+			ret = -ENOMEM;
+			goto out;
+		}
+
+		metadata_len = body_len;
+	}
+
+	if (metadata_buf_ptr + len > metadata_buf + metadata_len) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	memcpy(metadata_buf_ptr, buf, len);
+	metadata_buf_ptr += len;
+
+	if (last)
+		do_parse_metadata(previous_name_buf);
+out:
+	if (ret < 0 || last) {
+		kfree(metadata_buf);
+		metadata_buf = NULL;
+		metadata = 0;
+	}
+
+	return ret;
+}
+
 static int __init do_copy(void)
 {
 	if (byte_count >= body_len) {
 		if (xwrite(wfd, victim, body_len) != body_len)
 			error("write error");
+		if (metadata)
+			do_process_metadata(victim, body_len, true);
 		ksys_close(wfd);
 		do_utime(vcollected, mtime);
 		kfree(vcollected);
@@ -458,6 +500,8 @@  static int __init do_copy(void)
 	} else {
 		if (xwrite(wfd, victim, byte_count) != byte_count)
 			error("write error");
+		if (metadata)
+			do_process_metadata(victim, byte_count, false);
 		body_len -= byte_count;
 		eat(byte_count);
 		return 1;
@@ -467,6 +511,7 @@  static int __init do_copy(void)
 static int __init do_symlink(void)
 {
 	collected[N_ALIGN(name_len) + body_len] = '\0';
+	memcpy(previous_name_buf, collected, strlen(collected) + 1);
 	clean_path(collected, 0);
 	ksys_symlink(collected + N_ALIGN(name_len), collected);
 	ksys_lchown(collected, uid, gid);
@@ -534,8 +579,9 @@  static char * __init unpack_to_rootfs(char *buf, unsigned long len)
 	header_buf = kmalloc(110, GFP_KERNEL);
 	symlink_buf = kmalloc(PATH_MAX + N_ALIGN(PATH_MAX) + 1, GFP_KERNEL);
 	name_buf = kmalloc(N_ALIGN(PATH_MAX), GFP_KERNEL);
+	previous_name_buf = kmalloc(N_ALIGN(PATH_MAX), GFP_KERNEL);
 
-	if (!header_buf || !symlink_buf || !name_buf)
+	if (!header_buf || !symlink_buf || !name_buf || !previous_name_buf)
 		panic("can't allocate buffers");
 
 	state = Start;
@@ -580,6 +626,7 @@  static char * __init unpack_to_rootfs(char *buf, unsigned long len)
 		len -= my_inptr;
 	}
 	dir_utime();
+	kfree(previous_name_buf);
 	kfree(name_buf);
 	kfree(symlink_buf);
 	kfree(header_buf);