Merge git://git.kernel.org/pub/scm/linux/kernel/git/pkl/squashfs-linus

* git://git.kernel.org/pub/scm/linux/kernel/git/pkl/squashfs-linus:
  squashfs: update documentation to include description of xattr layout
  squashfs: fix name reading in squashfs_xattr_get
  squashfs: constify xattr handlers
  squashfs: xattr fix sparse warnings
  squashfs: xattr_lookup sparse fix
  squashfs: add xattr support configure option
  squashfs: add new extended inode types
  squashfs: add support for xattr reading
  squashfs: add xattr id support

Documentation/filesystems/squashfs.txt

@@ -38,7 +38,8 @@ Hard link support:		yes			no
 Real inode numbers:		yes			no
 32-bit uids/gids:		yes			no
 File creation time:		yes			no
-Xattr and ACL support:		no			no
+Xattr support:			yes			no
+ACL support:			no			no
 
 Squashfs compresses data, inodes and directories.  In addition, inode and
 directory data are highly compacted, and packed on byte boundaries.  Each
@@ -58,7 +59,7 @@ obtained from this site also.
 3. SQUASHFS FILESYSTEM DESIGN
 -----------------------------
 
-A squashfs filesystem consists of seven parts, packed together on a byte
+A squashfs filesystem consists of a maximum of eight parts, packed together on a byte
 alignment:
 
 	 ---------------
@@ -80,6 +81,9 @@ alignment:
 	|---------------|
 	|    uid/gid	|
 	|  lookup table	|
+	|---------------|
+	|     xattr     |
+	|     table	|
 	 ---------------
 
 Compressed data blocks are written to the filesystem as files are read from
@@ -192,6 +196,26 @@ This table is stored compressed into metadata blocks.  A second index table is
 used to locate these.  This second index table for speed of access (and because
 it is small) is read at mount time and cached in memory.
 
+3.7 Xattr table
+---------------
+
+The xattr table contains extended attributes for each inode.  The xattrs
+for each inode are stored in a list, each list entry containing a type,
+name and value field.  The type field encodes the xattr prefix
+("user.", "trusted." etc) and it also encodes how the name/value fields
+should be interpreted.  Currently the type indicates whether the value
+is stored inline (in which case the value field contains the xattr value),
+or if it is stored out of line (in which case the value field stores a
+reference to where the actual value is stored).  This allows large values
+to be stored out of line improving scanning and lookup performance and it
+also allows values to be de-duplicated, the value being stored once, and
+all other occurences holding an out of line reference to that value.
+
+The xattr lists are packed into compressed 8K metadata blocks.
+To reduce overhead in inodes, rather than storing the on-disk
+location of the xattr list inside each inode, a 32-bit xattr id
+is stored.  This xattr id is mapped into the location of the xattr
+list using a second xattr id lookup table.
 
 4. TODOS AND OUTSTANDING ISSUES
 -------------------------------
@@ -199,9 +223,7 @@ it is small) is read at mount time and cached in memory.
 4.1 Todo list
 -------------
 
-Implement Xattr and ACL support.  The Squashfs 4.0 filesystem layout has hooks
-for these but the code has not been written.  Once the code has been written
-the existing layout should not require modification.
+Implement ACL support.
 
 4.2 Squashfs internal cache
 ---------------------------

fs/squashfs/Kconfig

@@ -26,6 +26,17 @@ config SQUASHFS
 
 	  If unsure, say N.
 
+config SQUASHFS_XATTRS
+	bool "Squashfs XATTR support"
+	depends on SQUASHFS
+	default n
+	help
+	  Saying Y here includes support for extended attributes (xattrs).
+	  Xattrs are name:value pairs associated with inodes by
+	  the kernel or by users (see the attr(5) manual page).
+
+	  If unsure, say N.
+
 config SQUASHFS_EMBEDDED
 
 	bool "Additional option for memory-constrained systems" 

fs/squashfs/Makefile

@@ -5,3 +5,5 @@
 obj-$(CONFIG_SQUASHFS) += squashfs.o
 squashfs-y += block.o cache.o dir.o export.o file.o fragment.o id.o inode.o
 squashfs-y += namei.o super.o symlink.o zlib_wrapper.o decompressor.o
+squashfs-$(CONFIG_SQUASHFS_XATTRS) += xattr.o xattr_id.o
+

fs/squashfs/inode.c

@@ -40,11 +40,13 @@
 
 #include <linux/fs.h>
 #include <linux/vfs.h>
+#include <linux/xattr.h>
 
 #include "squashfs_fs.h"
 #include "squashfs_fs_sb.h"
 #include "squashfs_fs_i.h"
 #include "squashfs.h"
+#include "xattr.h"
 
 /*
  * Initialise VFS inode with the base inode information common to all
@@ -111,6 +113,7 @@ int squashfs_read_inode(struct inode *inode, long long ino)
 	int err, type, offset = SQUASHFS_INODE_OFFSET(ino);
 	union squashfs_inode squashfs_ino;
 	struct squashfs_base_inode *sqshb_ino = &squashfs_ino.base;
+	int xattr_id = SQUASHFS_INVALID_XATTR;
 
 	TRACE("Entered squashfs_read_inode\n");
 
@@ -199,8 +202,10 @@ int squashfs_read_inode(struct inode *inode, long long ino)
 			frag_offset = 0;
 		}
 
+		xattr_id = le32_to_cpu(sqsh_ino->xattr);
 		inode->i_nlink = le32_to_cpu(sqsh_ino->nlink);
 		inode->i_size = le64_to_cpu(sqsh_ino->file_size);
+		inode->i_op = &squashfs_inode_ops;
 		inode->i_fop = &generic_ro_fops;
 		inode->i_mode |= S_IFREG;
 		inode->i_blocks = ((inode->i_size -
@@ -251,6 +256,7 @@ int squashfs_read_inode(struct inode *inode, long long ino)
 		if (err < 0)
 			goto failed_read;
 
+		xattr_id = le32_to_cpu(sqsh_ino->xattr);
 		inode->i_nlink = le32_to_cpu(sqsh_ino->nlink);
 		inode->i_size = le32_to_cpu(sqsh_ino->file_size);
 		inode->i_op = &squashfs_dir_inode_ops;
@@ -280,21 +286,33 @@ int squashfs_read_inode(struct inode *inode, long long ino)
 
 		inode->i_nlink = le32_to_cpu(sqsh_ino->nlink);
 		inode->i_size = le32_to_cpu(sqsh_ino->symlink_size);
-		inode->i_op = &page_symlink_inode_operations;
+		inode->i_op = &squashfs_symlink_inode_ops;
 		inode->i_data.a_ops = &squashfs_symlink_aops;
 		inode->i_mode |= S_IFLNK;
 		squashfs_i(inode)->start = block;
 		squashfs_i(inode)->offset = offset;
 
+		if (type == SQUASHFS_LSYMLINK_TYPE) {
+			__le32 xattr;
+
+			err = squashfs_read_metadata(sb, NULL, &block,
+						&offset, inode->i_size);
+			if (err < 0)
+				goto failed_read;
+			err = squashfs_read_metadata(sb, &xattr, &block,
+						&offset, sizeof(xattr));
+			if (err < 0)
+				goto failed_read;
+			xattr_id = le32_to_cpu(xattr);
+		}
+
 		TRACE("Symbolic link inode %x:%x, start_block %llx, offset "
 				"%x\n", SQUASHFS_INODE_BLK(ino), offset,
 				block, offset);
 		break;
 	}
 	case SQUASHFS_BLKDEV_TYPE:
-	case SQUASHFS_CHRDEV_TYPE:
-	case SQUASHFS_LBLKDEV_TYPE:
-	case SQUASHFS_LCHRDEV_TYPE: {
+	case SQUASHFS_CHRDEV_TYPE: {
 		struct squashfs_dev_inode *sqsh_ino = &squashfs_ino.dev;
 		unsigned int rdev;
 
@@ -315,10 +333,32 @@ int squashfs_read_inode(struct inode *inode, long long ino)
 				SQUASHFS_INODE_BLK(ino), offset, rdev);
 		break;
 	}
+	case SQUASHFS_LBLKDEV_TYPE:
+	case SQUASHFS_LCHRDEV_TYPE: {
+		struct squashfs_ldev_inode *sqsh_ino = &squashfs_ino.ldev;
+		unsigned int rdev;
+
+		err = squashfs_read_metadata(sb, sqsh_ino, &block, &offset,
+				sizeof(*sqsh_ino));
+		if (err < 0)
+			goto failed_read;
+
+		if (type == SQUASHFS_LCHRDEV_TYPE)
+			inode->i_mode |= S_IFCHR;
+		else
+			inode->i_mode |= S_IFBLK;
+		xattr_id = le32_to_cpu(sqsh_ino->xattr);
+		inode->i_op = &squashfs_inode_ops;
+		inode->i_nlink = le32_to_cpu(sqsh_ino->nlink);
+		rdev = le32_to_cpu(sqsh_ino->rdev);
+		init_special_inode(inode, inode->i_mode, new_decode_dev(rdev));
+
+		TRACE("Device inode %x:%x, rdev %x\n",
+				SQUASHFS_INODE_BLK(ino), offset, rdev);
+		break;
+	}
 	case SQUASHFS_FIFO_TYPE:
-	case SQUASHFS_SOCKET_TYPE:
-	case SQUASHFS_LFIFO_TYPE:
-	case SQUASHFS_LSOCKET_TYPE: {
+	case SQUASHFS_SOCKET_TYPE: {
 		struct squashfs_ipc_inode *sqsh_ino = &squashfs_ino.ipc;
 
 		err = squashfs_read_metadata(sb, sqsh_ino, &block, &offset,
@@ -334,14 +374,52 @@ int squashfs_read_inode(struct inode *inode, long long ino)
 		init_special_inode(inode, inode->i_mode, 0);
 		break;
 	}
+	case SQUASHFS_LFIFO_TYPE:
+	case SQUASHFS_LSOCKET_TYPE: {
+		struct squashfs_lipc_inode *sqsh_ino = &squashfs_ino.lipc;
+
+		err = squashfs_read_metadata(sb, sqsh_ino, &block, &offset,
+				sizeof(*sqsh_ino));
+		if (err < 0)
+			goto failed_read;
+
+		if (type == SQUASHFS_LFIFO_TYPE)
+			inode->i_mode |= S_IFIFO;
+		else
+			inode->i_mode |= S_IFSOCK;
+		xattr_id = le32_to_cpu(sqsh_ino->xattr);
+		inode->i_op = &squashfs_inode_ops;
+		inode->i_nlink = le32_to_cpu(sqsh_ino->nlink);
+		init_special_inode(inode, inode->i_mode, 0);
+		break;
+	}
 	default:
 		ERROR("Unknown inode type %d in squashfs_iget!\n", type);
 		return -EINVAL;
 	}
 
+	if (xattr_id != SQUASHFS_INVALID_XATTR && msblk->xattr_id_table) {
+		err = squashfs_xattr_lookup(sb, xattr_id,
+					&squashfs_i(inode)->xattr_count,
+					&squashfs_i(inode)->xattr_size,
+					&squashfs_i(inode)->xattr);
+		if (err < 0)
+			goto failed_read;
+		inode->i_blocks += ((squashfs_i(inode)->xattr_size - 1) >> 9)
+				+ 1;
+	} else
+		squashfs_i(inode)->xattr_count = 0;
+
 	return 0;
 
 failed_read:
 	ERROR("Unable to read inode 0x%llx\n", ino);
 	return err;
 }
+
+
+const struct inode_operations squashfs_inode_ops = {
+	.getxattr = generic_getxattr,
+	.listxattr = squashfs_listxattr
+};
+

fs/squashfs/namei.c

@@ -57,11 +57,13 @@
 #include <linux/slab.h>
 #include <linux/string.h>
 #include <linux/dcache.h>
+#include <linux/xattr.h>
 
 #include "squashfs_fs.h"
 #include "squashfs_fs_sb.h"
 #include "squashfs_fs_i.h"
 #include "squashfs.h"
+#include "xattr.h"
 
 /*
  * Lookup name in the directory index, returning the location of the metadata
@@ -237,5 +239,7 @@ failed:
 
 
 const struct inode_operations squashfs_dir_inode_ops = {
-	.lookup = squashfs_lookup
+	.lookup = squashfs_lookup,
+	.getxattr = generic_getxattr,
+	.listxattr = squashfs_listxattr
 };

fs/squashfs/squashfs.h

@@ -73,8 +73,11 @@ extern struct inode *squashfs_iget(struct super_block *, long long,
 				unsigned int);
 extern int squashfs_read_inode(struct inode *, long long);
 
+/* xattr.c */
+extern ssize_t squashfs_listxattr(struct dentry *, char *, size_t);
+
 /*
- * Inodes, files and decompressor operations
+ * Inodes, files,  decompressor and xattr operations
  */
 
 /* dir.c */
@@ -86,11 +89,18 @@ extern const struct export_operations squashfs_export_ops;
 /* file.c */
 extern const struct address_space_operations squashfs_aops;
 
+/* inode.c */
+extern const struct inode_operations squashfs_inode_ops;
+
 /* namei.c */
 extern const struct inode_operations squashfs_dir_inode_ops;
 
 /* symlink.c */
 extern const struct address_space_operations squashfs_symlink_aops;
+extern const struct inode_operations squashfs_symlink_inode_ops;
+
+/* xattr.c */
+extern const struct xattr_handler *squashfs_xattr_handlers[];
 
 /* zlib_wrapper.c */
 extern const struct squashfs_decompressor squashfs_zlib_comp_ops;

fs/squashfs/squashfs_fs.h

@@ -46,6 +46,7 @@
 #define SQUASHFS_NAME_LEN		256
 
 #define SQUASHFS_INVALID_FRAG		(0xffffffffU)
+#define SQUASHFS_INVALID_XATTR		(0xffffffffU)
 #define SQUASHFS_INVALID_BLK		(-1LL)
 
 /* Filesystem flags */
@@ -96,6 +97,13 @@
 #define SQUASHFS_LFIFO_TYPE		13
 #define SQUASHFS_LSOCKET_TYPE		14
 
+/* Xattr types */
+#define SQUASHFS_XATTR_USER             0
+#define SQUASHFS_XATTR_TRUSTED          1
+#define SQUASHFS_XATTR_SECURITY         2
+#define SQUASHFS_XATTR_VALUE_OOL        256
+#define SQUASHFS_XATTR_PREFIX_MASK      0xff
+
 /* Flag whether block is compressed or uncompressed, bit is set if block is
  * uncompressed */
 #define SQUASHFS_COMPRESSED_BIT		(1 << 15)
@@ -174,6 +182,24 @@
 
 #define SQUASHFS_ID_BLOCK_BYTES(A)	(SQUASHFS_ID_BLOCKS(A) *\
 					sizeof(u64))
+/* xattr id lookup table defines */
+#define SQUASHFS_XATTR_BYTES(A)		((A) * sizeof(struct squashfs_xattr_id))
+
+#define SQUASHFS_XATTR_BLOCK(A)		(SQUASHFS_XATTR_BYTES(A) / \
+					SQUASHFS_METADATA_SIZE)
+
+#define SQUASHFS_XATTR_BLOCK_OFFSET(A)	(SQUASHFS_XATTR_BYTES(A) % \
+					SQUASHFS_METADATA_SIZE)
+
+#define SQUASHFS_XATTR_BLOCKS(A)	((SQUASHFS_XATTR_BYTES(A) + \
+					SQUASHFS_METADATA_SIZE - 1) / \
+					SQUASHFS_METADATA_SIZE)
+
+#define SQUASHFS_XATTR_BLOCK_BYTES(A)	(SQUASHFS_XATTR_BLOCKS(A) *\
+					sizeof(u64))
+#define SQUASHFS_XATTR_BLK(A)		((unsigned int) ((A) >> 16))
+
+#define SQUASHFS_XATTR_OFFSET(A)	((unsigned int) ((A) & 0xffff))
 
 /* cached data constants for filesystem */
 #define SQUASHFS_CACHED_BLKS		8
@@ -228,7 +254,7 @@ struct squashfs_super_block {
 	__le64			root_inode;
 	__le64			bytes_used;
 	__le64			id_table_start;
-	__le64			xattr_table_start;
+	__le64			xattr_id_table_start;
 	__le64			inode_table_start;
 	__le64			directory_table_start;
 	__le64			fragment_table_start;
@@ -261,6 +287,17 @@ struct squashfs_ipc_inode {
 	__le32			nlink;
 };
 
+struct squashfs_lipc_inode {
+	__le16			inode_type;
+	__le16			mode;
+	__le16			uid;
+	__le16			guid;
+	__le32			mtime;
+	__le32	 		inode_number;
+	__le32			nlink;
+	__le32			xattr;
+};
+
 struct squashfs_dev_inode {
 	__le16			inode_type;
 	__le16			mode;
@@ -272,6 +309,18 @@ struct squashfs_dev_inode {
 	__le32			rdev;
 };
 
+struct squashfs_ldev_inode {
+	__le16			inode_type;
+	__le16			mode;
+	__le16			uid;
+	__le16			guid;
+	__le32			mtime;
+	__le32	 		inode_number;
+	__le32			nlink;
+	__le32			rdev;
+	__le32			xattr;
+};
+
 struct squashfs_symlink_inode {
 	__le16			inode_type;
 	__le16			mode;
@@ -349,12 +398,14 @@ struct squashfs_ldir_inode {
 union squashfs_inode {
 	struct squashfs_base_inode		base;
 	struct squashfs_dev_inode		dev;
+	struct squashfs_ldev_inode		ldev;
 	struct squashfs_symlink_inode		symlink;
 	struct squashfs_reg_inode		reg;
 	struct squashfs_lreg_inode		lreg;
 	struct squashfs_dir_inode		dir;
 	struct squashfs_ldir_inode		ldir;
 	struct squashfs_ipc_inode		ipc;
+	struct squashfs_lipc_inode		lipc;
 };
 
 struct squashfs_dir_entry {
@@ -377,4 +428,27 @@ struct squashfs_fragment_entry {
 	unsigned int		unused;
 };
 
+struct squashfs_xattr_entry {
+	__le16			type;
+	__le16			size;
+	char			data[0];
+};
+
+struct squashfs_xattr_val {
+	__le32			vsize;
+	char			value[0];
+};
+
+struct squashfs_xattr_id {
+	__le64			xattr;
+	__le32			count;
+	__le32			size;
+};
+
+struct squashfs_xattr_id_table {
+	__le64			xattr_table_start;
+	__le32			xattr_ids;
+	__le32			unused;
+};
+
 #endif

fs/squashfs/squashfs_fs_i.h

@@ -26,6 +26,9 @@
 struct squashfs_inode_info {
 	u64		start;
 	int		offset;
+	u64		xattr;
+	unsigned int	xattr_size;
+	int		xattr_count;
 	union {
 		struct {
 			u64		fragment_block;

fs/squashfs/squashfs_fs_sb.h

@@ -61,6 +61,7 @@ struct squashfs_sb_info {
 	int					next_meta_index;
 	__le64					*id_table;
 	__le64					*fragment_index;
+	__le64					*xattr_id_table;
 	struct mutex				read_data_mutex;
 	struct mutex				meta_index_mutex;
 	struct meta_index			*meta_index;
@@ -68,9 +69,11 @@ struct squashfs_sb_info {
 	__le64					*inode_lookup_table;
 	u64					inode_table;
 	u64					directory_table;
+	u64					xattr_table;
 	unsigned int				block_size;
 	unsigned short				block_log;
 	long long				bytes_used;
 	unsigned int				inodes;
+	int					xattr_ids;
 };
 #endif

fs/squashfs/super.c

@@ -36,12 +36,14 @@
 #include <linux/init.h>
 #include <linux/module.h>
 #include <linux/magic.h>
+#include <linux/xattr.h>
 
 #include "squashfs_fs.h"
 #include "squashfs_fs_sb.h"
 #include "squashfs_fs_i.h"
 #include "squashfs.h"
 #include "decompressor.h"
+#include "xattr.h"
 
 static struct file_system_type squashfs_fs_type;
 static const struct super_operations squashfs_super_ops;
@@ -82,7 +84,7 @@ static int squashfs_fill_super(struct super_block *sb, void *data, int silent)
 	long long root_inode;
 	unsigned short flags;
 	unsigned int fragments;
-	u64 lookup_table_start;
+	u64 lookup_table_start, xattr_id_table_start;
 	int err;
 
 	TRACE("Entered squashfs_fill_superblock\n");
@@ -139,13 +141,6 @@ static int squashfs_fill_super(struct super_block *sb, void *data, int silent)
 	if (msblk->decompressor == NULL)
 		goto failed_mount;
 
-	/*
-	 * Check if there's xattrs in the filesystem.  These are not
-	 * supported in this version, so warn that they will be ignored.
-	 */
-	if (le64_to_cpu(sblk->xattr_table_start) != SQUASHFS_INVALID_BLK)
-		ERROR("Xattrs in filesystem, these will be ignored\n");
-
 	/* Check the filesystem does not extend beyond the end of the
 	   block device */
 	msblk->bytes_used = le64_to_cpu(sblk->bytes_used);
@@ -253,7 +248,7 @@ static int squashfs_fill_super(struct super_block *sb, void *data, int silent)
 allocate_lookup_table:
 	lookup_table_start = le64_to_cpu(sblk->lookup_table_start);
 	if (lookup_table_start == SQUASHFS_INVALID_BLK)
-		goto allocate_root;
+		goto allocate_xattr_table;
 
 	/* Allocate and read inode lookup table */
 	msblk->inode_lookup_table = squashfs_read_inode_lookup_table(sb,
@@ -266,6 +261,21 @@ allocate_lookup_table:
 
 	sb->s_export_op = &squashfs_export_ops;
 
+allocate_xattr_table:
+	sb->s_xattr = squashfs_xattr_handlers;
+	xattr_id_table_start = le64_to_cpu(sblk->xattr_id_table_start);
+	if (xattr_id_table_start == SQUASHFS_INVALID_BLK)
+		goto allocate_root;
+
+	/* Allocate and read xattr id lookup table */
+	msblk->xattr_id_table = squashfs_read_xattr_id_table(sb,
+		xattr_id_table_start, &msblk->xattr_table, &msblk->xattr_ids);
+	if (IS_ERR(msblk->xattr_id_table)) {
+		err = PTR_ERR(msblk->xattr_id_table);
+		msblk->xattr_id_table = NULL;
+		if (err != -ENOTSUPP)
+			goto failed_mount;
+	}
 allocate_root:
 	root = new_inode(sb);
 	if (!root) {
@@ -301,6 +311,7 @@ failed_mount:
 	kfree(msblk->inode_lookup_table);
 	kfree(msblk->fragment_index);
 	kfree(msblk->id_table);
+	kfree(msblk->xattr_id_table);
 	kfree(sb->s_fs_info);
 	sb->s_fs_info = NULL;
 	kfree(sblk);
@@ -355,6 +366,7 @@ static void squashfs_put_super(struct super_block *sb)
 		kfree(sbi->fragment_index);
 		kfree(sbi->meta_index);
 		kfree(sbi->inode_lookup_table);
+		kfree(sbi->xattr_id_table);
 		kfree(sb->s_fs_info);
 		sb->s_fs_info = NULL;
 	}

fs/squashfs/symlink.c

@@ -35,11 +35,13 @@
 #include <linux/kernel.h>
 #include <linux/string.h>
 #include <linux/pagemap.h>
+#include <linux/xattr.h>
 
 #include "squashfs_fs.h"
 #include "squashfs_fs_sb.h"
 #include "squashfs_fs_i.h"
 #include "squashfs.h"
+#include "xattr.h"
 
 static int squashfs_symlink_readpage(struct file *file, struct page *page)
 {
@@ -114,3 +116,12 @@ error_out:
 const struct address_space_operations squashfs_symlink_aops = {
 	.readpage = squashfs_symlink_readpage
 };
+
+const struct inode_operations squashfs_symlink_inode_ops = {
+	.readlink = generic_readlink,
+	.follow_link = page_follow_link_light,
+	.put_link = page_put_link,
+	.getxattr = generic_getxattr,
+	.listxattr = squashfs_listxattr
+};
+

fs/squashfs/xattr.c

@@ -0,0 +1,323 @@
+/*
+ * Squashfs - a compressed read only filesystem for Linux
+ *
+ * Copyright (c) 2010
+ * Phillip Lougher <phillip@lougher.demon.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2,
+ * or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * xattr_id.c
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/string.h>
+#include <linux/fs.h>
+#include <linux/vfs.h>
+#include <linux/xattr.h>
+#include <linux/slab.h>
+
+#include "squashfs_fs.h"
+#include "squashfs_fs_sb.h"
+#include "squashfs_fs_i.h"
+#include "squashfs.h"
+
+static const struct xattr_handler *squashfs_xattr_handler(int);
+
+ssize_t squashfs_listxattr(struct dentry *d, char *buffer,
+	size_t buffer_size)
+{
+	struct inode *inode = d->d_inode;
+	struct super_block *sb = inode->i_sb;
+	struct squashfs_sb_info *msblk = sb->s_fs_info;
+	u64 start = SQUASHFS_XATTR_BLK(squashfs_i(inode)->xattr)
+						 + msblk->xattr_table;
+	int offset = SQUASHFS_XATTR_OFFSET(squashfs_i(inode)->xattr);
+	int count = squashfs_i(inode)->xattr_count;
+	size_t rest = buffer_size;
+	int err;
+
+	/* check that the file system has xattrs */
+	if (msblk->xattr_id_table == NULL)
+		return -EOPNOTSUPP;
+
+	/* loop reading each xattr name */
+	while (count--) {
+		struct squashfs_xattr_entry entry;
+		struct squashfs_xattr_val val;
+		const struct xattr_handler *handler;
+		int name_size, prefix_size = 0;
+
+		err = squashfs_read_metadata(sb, &entry, &start, &offset,
+							sizeof(entry));
+		if (err < 0)
+			goto failed;
+
+		name_size = le16_to_cpu(entry.size);
+		handler = squashfs_xattr_handler(le16_to_cpu(entry.type));
+		if (handler)
+			prefix_size = handler->list(d, buffer, rest, NULL,
+				name_size, handler->flags);
+		if (prefix_size) {
+			if (buffer) {
+				if (prefix_size + name_size + 1 > rest) {
+					err = -ERANGE;
+					goto failed;
+				}
+				buffer += prefix_size;
+			}
+			err = squashfs_read_metadata(sb, buffer, &start,
+				&offset, name_size);
+			if (err < 0)
+				goto failed;
+			if (buffer) {
+				buffer[name_size] = '\0';
+				buffer += name_size + 1;
+			}
+			rest -= prefix_size + name_size + 1;
+		} else  {
+			/* no handler or insuffficient privileges, so skip */
+			err = squashfs_read_metadata(sb, NULL, &start,
+				&offset, name_size);
+			if (err < 0)
+				goto failed;
+		}
+
+
+		/* skip remaining xattr entry */
+		err = squashfs_read_metadata(sb, &val, &start, &offset,
+						sizeof(val));
+		if (err < 0)
+			goto failed;
+
+		err = squashfs_read_metadata(sb, NULL, &start, &offset,
+						le32_to_cpu(val.vsize));
+		if (err < 0)
+			goto failed;
+	}
+	err = buffer_size - rest;
+
+failed:
+	return err;
+}
+
+
+static int squashfs_xattr_get(struct inode *inode, int name_index,
+	const char *name, void *buffer, size_t buffer_size)
+{
+	struct super_block *sb = inode->i_sb;
+	struct squashfs_sb_info *msblk = sb->s_fs_info;
+	u64 start = SQUASHFS_XATTR_BLK(squashfs_i(inode)->xattr)
+						 + msblk->xattr_table;
+	int offset = SQUASHFS_XATTR_OFFSET(squashfs_i(inode)->xattr);
+	int count = squashfs_i(inode)->xattr_count;
+	int name_len = strlen(name);
+	int err, vsize;
+	char *target = kmalloc(name_len, GFP_KERNEL);
+
+	if (target == NULL)
+		return  -ENOMEM;
+
+	/* loop reading each xattr name */
+	for (; count; count--) {
+		struct squashfs_xattr_entry entry;
+		struct squashfs_xattr_val val;
+		int type, prefix, name_size;
+
+		err = squashfs_read_metadata(sb, &entry, &start, &offset,
+							sizeof(entry));
+		if (err < 0)
+			goto failed;
+
+		name_size = le16_to_cpu(entry.size);
+		type = le16_to_cpu(entry.type);
+		prefix = type & SQUASHFS_XATTR_PREFIX_MASK;
+
+		if (prefix == name_index && name_size == name_len)
+			err = squashfs_read_metadata(sb, target, &start,
+						&offset, name_size);
+		else
+			err = squashfs_read_metadata(sb, NULL, &start,
+						&offset, name_size);
+		if (err < 0)
+			goto failed;
+
+		if (prefix == name_index && name_size == name_len &&
+					strncmp(target, name, name_size) == 0) {
+			/* found xattr */
+			if (type & SQUASHFS_XATTR_VALUE_OOL) {
+				__le64 xattr;
+				/* val is a reference to the real location */
+				err = squashfs_read_metadata(sb, &val, &start,
+						&offset, sizeof(val));
+				if (err < 0)
+					goto failed;
+				err = squashfs_read_metadata(sb, &xattr, &start,
+					 &offset, sizeof(xattr));
+				if (err < 0)
+					goto failed;
+				xattr = le64_to_cpu(xattr);
+				start = SQUASHFS_XATTR_BLK(xattr) +
+							msblk->xattr_table;
+				offset = SQUASHFS_XATTR_OFFSET(xattr);
+			}
+			/* read xattr value */
+			err = squashfs_read_metadata(sb, &val, &start, &offset,
+							sizeof(val));
+			if (err < 0)
+				goto failed;
+
+			vsize = le32_to_cpu(val.vsize);
+			if (buffer) {
+				if (vsize > buffer_size) {
+					err = -ERANGE;
+					goto failed;
+				}
+				err = squashfs_read_metadata(sb, buffer, &start,
+					 &offset, vsize);
+				if (err < 0)
+					goto failed;
+			}
+			break;
+		}
+
+		/* no match, skip remaining xattr entry */
+		err = squashfs_read_metadata(sb, &val, &start, &offset,
+							sizeof(val));
+		if (err < 0)
+			goto failed;
+		err = squashfs_read_metadata(sb, NULL, &start, &offset,
+						le32_to_cpu(val.vsize));
+		if (err < 0)
+			goto failed;
+	}
+	err = count ? vsize : -ENODATA;
+
+failed:
+	kfree(target);
+	return err;
+}
+
+
+/*
+ * User namespace support
+ */
+static size_t squashfs_user_list(struct dentry *d, char *list, size_t list_size,
+	const char *name, size_t name_len, int type)
+{
+	if (list && XATTR_USER_PREFIX_LEN <= list_size)
+		memcpy(list, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN);
+	return XATTR_USER_PREFIX_LEN;
+}
+
+static int squashfs_user_get(struct dentry *d, const char *name, void *buffer,
+	size_t size, int type)
+{
+	if (name[0] == '\0')
+		return  -EINVAL;
+
+	return squashfs_xattr_get(d->d_inode, SQUASHFS_XATTR_USER, name,
+		buffer, size);
+}
+
+static const struct xattr_handler squashfs_xattr_user_handler = {
+	.prefix	= XATTR_USER_PREFIX,
+	.list	= squashfs_user_list,
+	.get	= squashfs_user_get
+};
+
+/*
+ * Trusted namespace support
+ */
+static size_t squashfs_trusted_list(struct dentry *d, char *list,
+	size_t list_size, const char *name, size_t name_len, int type)
+{
+	if (!capable(CAP_SYS_ADMIN))
+		return 0;
+
+	if (list && XATTR_TRUSTED_PREFIX_LEN <= list_size)
+		memcpy(list, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN);
+	return XATTR_TRUSTED_PREFIX_LEN;
+}
+
+static int squashfs_trusted_get(struct dentry *d, const char *name,
+	void *buffer, size_t size, int type)
+{
+	if (name[0] == '\0')
+		return  -EINVAL;
+
+	return squashfs_xattr_get(d->d_inode, SQUASHFS_XATTR_TRUSTED, name,
+		buffer, size);
+}
+
+static const struct xattr_handler squashfs_xattr_trusted_handler = {
+	.prefix	= XATTR_TRUSTED_PREFIX,
+	.list	= squashfs_trusted_list,
+	.get	= squashfs_trusted_get
+};
+
+/*
+ * Security namespace support
+ */
+static size_t squashfs_security_list(struct dentry *d, char *list,
+	size_t list_size, const char *name, size_t name_len, int type)
+{
+	if (list && XATTR_SECURITY_PREFIX_LEN <= list_size)
+		memcpy(list, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN);
+	return XATTR_SECURITY_PREFIX_LEN;
+}
+
+static int squashfs_security_get(struct dentry *d, const char *name,
+	void *buffer, size_t size, int type)
+{
+	if (name[0] == '\0')
+		return  -EINVAL;
+
+	return squashfs_xattr_get(d->d_inode, SQUASHFS_XATTR_SECURITY, name,
+		buffer, size);
+}
+
+static const struct xattr_handler squashfs_xattr_security_handler = {
+	.prefix	= XATTR_SECURITY_PREFIX,
+	.list	= squashfs_security_list,
+	.get	= squashfs_security_get
+};
+
+static inline const struct xattr_handler *squashfs_xattr_handler(int type)
+{
+	if (type & ~(SQUASHFS_XATTR_PREFIX_MASK | SQUASHFS_XATTR_VALUE_OOL))
+		/* ignore unrecognised type */
+		return NULL;
+
+	switch (type & SQUASHFS_XATTR_PREFIX_MASK) {
+	case SQUASHFS_XATTR_USER:
+		return &squashfs_xattr_user_handler;
+	case SQUASHFS_XATTR_TRUSTED:
+		return &squashfs_xattr_trusted_handler;
+	case SQUASHFS_XATTR_SECURITY:
+		return &squashfs_xattr_security_handler;
+	default:
+		/* ignore unrecognised type */
+		return NULL;
+	}
+}
+
+const struct xattr_handler *squashfs_xattr_handlers[] = {
+	&squashfs_xattr_user_handler,
+	&squashfs_xattr_trusted_handler,
+	&squashfs_xattr_security_handler,
+	NULL
+};
+

fs/squashfs/xattr.h

@@ -0,0 +1,46 @@
+/*
+ * Squashfs - a compressed read only filesystem for Linux
+ *
+ * Copyright (c) 2010
+ * Phillip Lougher <phillip@lougher.demon.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2,
+ * or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * xattr.h
+ */
+
+#ifdef CONFIG_SQUASHFS_XATTRS
+extern __le64 *squashfs_read_xattr_id_table(struct super_block *, u64,
+		u64 *, int *);
+extern int squashfs_xattr_lookup(struct super_block *, unsigned int, int *,
+		int *, unsigned long long *);
+#else
+static inline __le64 *squashfs_read_xattr_id_table(struct super_block *sb,
+		u64 start, u64 *xattr_table_start, int *xattr_ids)
+{
+	ERROR("Xattrs in filesystem, these will be ignored\n");
+	return ERR_PTR(-ENOTSUPP);
+}
+
+static inline int squashfs_xattr_lookup(struct super_block *sb,
+		unsigned int index, int *count, int *size,
+		unsigned long long *xattr)
+{
+	return 0;
+}
+#define squashfs_listxattr NULL
+#define generic_getxattr NULL
+#define squashfs_xattr_handlers NULL
+#endif

fs/squashfs/xattr_id.c

@@ -0,0 +1,100 @@
+/*
+ * Squashfs - a compressed read only filesystem for Linux
+ *
+ * Copyright (c) 2010
+ * Phillip Lougher <phillip@lougher.demon.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2,
+ * or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * xattr_id.c
+ */
+
+/*
+ * This file implements code to map the 32-bit xattr id stored in the inode
+ * into the on disk location of the xattr data.
+ */
+
+#include <linux/fs.h>
+#include <linux/vfs.h>
+#include <linux/slab.h>
+
+#include "squashfs_fs.h"
+#include "squashfs_fs_sb.h"
+#include "squashfs_fs_i.h"
+#include "squashfs.h"
+
+/*
+ * Map xattr id using the xattr id look up table
+ */
+int squashfs_xattr_lookup(struct super_block *sb, unsigned int index,
+		int *count, unsigned int *size, unsigned long long *xattr)
+{
+	struct squashfs_sb_info *msblk = sb->s_fs_info;
+	int block = SQUASHFS_XATTR_BLOCK(index);
+	int offset = SQUASHFS_XATTR_BLOCK_OFFSET(index);
+	u64 start_block = le64_to_cpu(msblk->xattr_id_table[block]);
+	struct squashfs_xattr_id id;
+	int err;
+
+	err = squashfs_read_metadata(sb, &id, &start_block, &offset,
+							sizeof(id));
+	if (err < 0)
+		return err;
+
+	*xattr = le64_to_cpu(id.xattr);
+	*size = le32_to_cpu(id.size);
+	*count = le32_to_cpu(id.count);
+	return 0;
+}
+
+
+/*
+ * Read uncompressed xattr id lookup table indexes from disk into memory
+ */
+__le64 *squashfs_read_xattr_id_table(struct super_block *sb, u64 start,
+		u64 *xattr_table_start, int *xattr_ids)
+{
+	unsigned int len;
+	__le64 *xid_table;
+	struct squashfs_xattr_id_table id_table;
+	int err;
+
+	err = squashfs_read_table(sb, &id_table, start, sizeof(id_table));
+	if (err < 0) {
+		ERROR("unable to read xattr id table\n");
+		return ERR_PTR(err);
+	}
+	*xattr_table_start = le64_to_cpu(id_table.xattr_table_start);
+	*xattr_ids = le32_to_cpu(id_table.xattr_ids);
+	len = SQUASHFS_XATTR_BLOCK_BYTES(*xattr_ids);
+
+	TRACE("In read_xattr_index_table, length %d\n", len);
+
+	/* Allocate xattr id lookup table indexes */
+	xid_table = kmalloc(len, GFP_KERNEL);
+	if (xid_table == NULL) {
+		ERROR("Failed to allocate xattr id index table\n");
+		return ERR_PTR(-ENOMEM);
+	}
+
+	err = squashfs_read_table(sb, xid_table, start + sizeof(id_table), len);
+	if (err < 0) {
+		ERROR("unable to read xattr id index table\n");
+		kfree(xid_table);
+		return ERR_PTR(err);
+	}
+
+	return xid_table;
+}