diff options
Diffstat (limited to 'fs/squashfs/xattr_id.c')
| -rw-r--r-- | fs/squashfs/xattr_id.c | 145 |
1 files changed, 145 insertions, 0 deletions
diff --git a/fs/squashfs/xattr_id.c b/fs/squashfs/xattr_id.c new file mode 100644 index 000000000..7f718d2bf --- /dev/null +++ b/fs/squashfs/xattr_id.c @@ -0,0 +1,145 @@ +/* + * Squashfs - a compressed read only filesystem for Linux + * + * Copyright (c) 2010 + * Phillip Lougher <phillip@squashfs.org.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.h" +#include "xattr.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; + struct squashfs_xattr_id id; + int err; + + if (index >= msblk->xattr_ids) + return -EINVAL; + + start_block = le64_to_cpu(msblk->xattr_id_table[block]); + + 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 table_start, + u64 *xattr_table_start, int *xattr_ids) +{ + struct squashfs_sb_info *msblk = sb->s_fs_info; + unsigned int len, indexes; + struct squashfs_xattr_id_table *id_table; + __le64 *table; + u64 start, end; + int n; + + id_table = squashfs_read_table(sb, table_start, sizeof(*id_table)); + if (IS_ERR(id_table)) + return (__le64 *) id_table; + + *xattr_table_start = le64_to_cpu(id_table->xattr_table_start); + *xattr_ids = le32_to_cpu(id_table->xattr_ids); + kfree(id_table); + + /* Sanity check values */ + + /* there is always at least one xattr id */ + if (*xattr_ids == 0) + return ERR_PTR(-EINVAL); + + len = SQUASHFS_XATTR_BLOCK_BYTES(*xattr_ids); + indexes = SQUASHFS_XATTR_BLOCKS(*xattr_ids); + + /* + * The computed size of the index table (len bytes) should exactly + * match the table start and end points + */ + start = table_start + sizeof(*id_table); + end = msblk->bytes_used; + + if (len != (end - start)) + return ERR_PTR(-EINVAL); + + table = squashfs_read_table(sb, start, len); + if (IS_ERR(table)) + return table; + + /* table[0], table[1], ... table[indexes - 1] store the locations + * of the compressed xattr id blocks. Each entry should be less than + * the next (i.e. table[0] < table[1]), and the difference between them + * should be SQUASHFS_METADATA_SIZE or less. table[indexes - 1] + * should be less than table_start, and again the difference + * shouls be SQUASHFS_METADATA_SIZE or less. + * + * Finally xattr_table_start should be less than table[0]. + */ + for (n = 0; n < (indexes - 1); n++) { + start = le64_to_cpu(table[n]); + end = le64_to_cpu(table[n + 1]); + + if (start >= end || (end - start) > + (SQUASHFS_METADATA_SIZE + SQUASHFS_BLOCK_OFFSET)) { + kfree(table); + return ERR_PTR(-EINVAL); + } + } + + start = le64_to_cpu(table[indexes - 1]); + if (start >= table_start || (table_start - start) > + (SQUASHFS_METADATA_SIZE + SQUASHFS_BLOCK_OFFSET)) { + kfree(table); + return ERR_PTR(-EINVAL); + } + + if (*xattr_table_start >= le64_to_cpu(table[0])) { + kfree(table); + return ERR_PTR(-EINVAL); + } + + return table; +} |