squashfs: add support for xattr reading
Phillip Lougher [Mon, 17 May 2010 02:17:04 +0000 (03:17 +0100)]
Add support for listxattr and getxattr.  Also add xattr definitions.

Signed-off-by: Phillip Lougher <phillip@lougher.demon.co.uk>

fs/squashfs/Makefile
fs/squashfs/squashfs_fs.h
fs/squashfs/squashfs_fs_i.h
fs/squashfs/xattr.c [new file with mode: 0644]

index c0da4a1..56684d4 100644 (file)
@@ -5,5 +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-y += xattr_id.o
+squashfs-y += xattr.o xattr_id.o
 
index c654e86..6fe940c 100644 (file)
@@ -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 */
 #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)
@@ -395,6 +403,17 @@ 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;
index fbfca30..d3e3a37 100644 (file)
@@ -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;
diff --git a/fs/squashfs/xattr.c b/fs/squashfs/xattr.c
new file mode 100644 (file)
index 0000000..147ecc3
--- /dev/null
@@ -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
+};
+