squashfs: add support for xattr reading
Add support for listxattr and getxattr. Also add xattr definitions.
Signed-off-by: Phillip Lougher <phillip@lougher.demon.co.uk>
diff --git a/fs/squashfs/xattr.c b/fs/squashfs/xattr.c
new file mode 100644
index 0000000..147ecc3
--- /dev/null
+++ b/fs/squashfs/xattr.c
@@ -0,0 +1,319 @@
+/*
+ * 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 inline 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;
+ 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;
+
+ err = squashfs_read_metadata(sb, target, &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);
+}
+
+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);
+}
+
+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);
+}
+
+struct xattr_handler squashfs_xattr_security_handler = {
+ .prefix = XATTR_SECURITY_PREFIX,
+ .list = squashfs_security_list,
+ .get = squashfs_security_get
+};
+
+static inline 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;
+ }
+}
+
+struct xattr_handler *squashfs_xattr_handlers[] = {
+ &squashfs_xattr_user_handler,
+ &squashfs_xattr_trusted_handler,
+ &squashfs_xattr_security_handler,
+ NULL
+};
+