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fs/btrfs/xattr.c
10.8 KB
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/* * Copyright (C) 2007 Red Hat. All rights reserved. * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public * License v2 as published by the Free Software Foundation. * * 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, Inc., 59 Temple Place - Suite 330, * Boston, MA 021110-1307, USA. */ #include <linux/init.h> #include <linux/fs.h> #include <linux/slab.h> #include <linux/rwsem.h> #include <linux/xattr.h> |
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#include <linux/security.h> |
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#include "ctree.h" #include "btrfs_inode.h" #include "transaction.h" #include "xattr.h" #include "disk-io.h" |
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ssize_t __btrfs_getxattr(struct inode *inode, const char *name, void *buffer, size_t size) |
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{ struct btrfs_dir_item *di; struct btrfs_root *root = BTRFS_I(inode)->root; struct btrfs_path *path; struct extent_buffer *leaf; |
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int ret = 0; unsigned long data_ptr; |
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path = btrfs_alloc_path(); |
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if (!path) |
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return -ENOMEM; |
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|
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/* lookup the xattr by name */ |
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di = btrfs_lookup_xattr(NULL, root, path, btrfs_ino(inode), name, |
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strlen(name), 0); |
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if (!di) { |
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ret = -ENODATA; goto out; |
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} else if (IS_ERR(di)) { ret = PTR_ERR(di); goto out; |
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} leaf = path->nodes[0]; /* if size is 0, that means we want the size of the attr */ if (!size) { ret = btrfs_dir_data_len(leaf, di); goto out; } /* now get the data out of our dir_item */ if (btrfs_dir_data_len(leaf, di) > size) { ret = -ERANGE; goto out; } |
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/* * The way things are packed into the leaf is like this * |struct btrfs_dir_item|name|data| * where name is the xattr name, so security.foo, and data is the * content of the xattr. data_ptr points to the location in memory * where the data starts in the in memory leaf */ |
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data_ptr = (unsigned long)((char *)(di + 1) + btrfs_dir_name_len(leaf, di)); read_extent_buffer(leaf, buffer, data_ptr, |
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btrfs_dir_data_len(leaf, di)); |
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ret = btrfs_dir_data_len(leaf, di); out: |
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btrfs_free_path(path); return ret; } |
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static int do_setxattr(struct btrfs_trans_handle *trans, struct inode *inode, const char *name, const void *value, size_t size, int flags) |
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{ struct btrfs_dir_item *di; struct btrfs_root *root = BTRFS_I(inode)->root; |
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struct btrfs_path *path; |
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size_t name_len = strlen(name); int ret = 0; if (name_len + size > BTRFS_MAX_XATTR_SIZE(root)) return -ENOSPC; |
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path = btrfs_alloc_path(); |
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if (!path) |
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return -ENOMEM; |
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|
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if (flags & XATTR_REPLACE) { di = btrfs_lookup_xattr(trans, root, path, btrfs_ino(inode), name, name_len, -1); if (IS_ERR(di)) { ret = PTR_ERR(di); goto out; } else if (!di) { ret = -ENODATA; |
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goto out; } |
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ret = btrfs_delete_one_dir_name(trans, root, path, di); |
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if (ret) goto out; |
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btrfs_release_path(path); |
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/* * remove the attribute */ if (!value) goto out; |
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} |
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|
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again: ret = btrfs_insert_xattr_item(trans, root, path, btrfs_ino(inode), name, name_len, value, size); |
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/* * If we're setting an xattr to a new value but the new value is say * exactly BTRFS_MAX_XATTR_SIZE, we could end up with EOVERFLOW getting * back from split_leaf. This is because it thinks we'll be extending * the existing item size, but we're asking for enough space to add the * item itself. So if we get EOVERFLOW just set ret to EEXIST and let * the rest of the function figure it out. */ if (ret == -EOVERFLOW) ret = -EEXIST; |
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if (ret == -EEXIST) { if (flags & XATTR_CREATE) |
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goto out; |
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/* * We can't use the path we already have since we won't have the * proper locking for a delete, so release the path and * re-lookup to delete the thing. */ |
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btrfs_release_path(path); |
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di = btrfs_lookup_xattr(trans, root, path, btrfs_ino(inode), name, name_len, -1); if (IS_ERR(di)) { ret = PTR_ERR(di); goto out; } else if (!di) { /* Shouldn't happen but just in case... */ btrfs_release_path(path); goto again; } |
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|
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ret = btrfs_delete_one_dir_name(trans, root, path, di); if (ret) |
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goto out; |
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/* * We have a value to set, so go back and try to insert it now. */ if (value) { btrfs_release_path(path); goto again; |
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} |
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} |
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out: btrfs_free_path(path); return ret; } |
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/* * @value: "" makes the attribute to empty, NULL removes it */ |
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int __btrfs_setxattr(struct btrfs_trans_handle *trans, struct inode *inode, const char *name, const void *value, size_t size, int flags) { struct btrfs_root *root = BTRFS_I(inode)->root; int ret; if (trans) return do_setxattr(trans, inode, name, value, size, flags); |
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trans = btrfs_start_transaction(root, 2); if (IS_ERR(trans)) return PTR_ERR(trans); |
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|
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ret = do_setxattr(trans, inode, name, value, size, flags); if (ret) goto out; inode->i_ctime = CURRENT_TIME; ret = btrfs_update_inode(trans, root, inode); BUG_ON(ret); out: btrfs_end_transaction_throttle(trans, root); |
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return ret; } ssize_t btrfs_listxattr(struct dentry *dentry, char *buffer, size_t size) { struct btrfs_key key, found_key; struct inode *inode = dentry->d_inode; struct btrfs_root *root = BTRFS_I(inode)->root; struct btrfs_path *path; |
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struct extent_buffer *leaf; struct btrfs_dir_item *di; |
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int ret = 0, slot; |
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size_t total_size = 0, size_left = size; |
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unsigned long name_ptr; |
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size_t name_len; |
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/* * ok we want all objects associated with this id. * NOTE: we set key.offset = 0; because we want to start with the * first xattr that we find and walk forward */ |
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key.objectid = btrfs_ino(inode); |
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btrfs_set_key_type(&key, BTRFS_XATTR_ITEM_KEY); key.offset = 0; path = btrfs_alloc_path(); |
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if (!path) return -ENOMEM; |
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path->reada = 2; |
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|
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/* search for our xattrs */ ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); if (ret < 0) goto err; |
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while (1) { leaf = path->nodes[0]; |
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slot = path->slots[0]; /* this is where we start walking through the path */ |
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if (slot >= btrfs_header_nritems(leaf)) { |
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/* * if we've reached the last slot in this leaf we need * to go to the next leaf and reset everything */ |
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ret = btrfs_next_leaf(root, path); if (ret < 0) goto err; else if (ret > 0) break; continue; |
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} |
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btrfs_item_key_to_cpu(leaf, &found_key, slot); /* check to make sure this item is what we want */ if (found_key.objectid != key.objectid) break; if (btrfs_key_type(&found_key) != BTRFS_XATTR_ITEM_KEY) break; di = btrfs_item_ptr(leaf, slot, struct btrfs_dir_item); |
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if (verify_dir_item(root, leaf, di)) continue; |
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name_len = btrfs_dir_name_len(leaf, di); total_size += name_len + 1; |
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/* we are just looking for how big our buffer needs to be */ if (!size) |
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goto next; |
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if (!buffer || (name_len + 1) > size_left) { |
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ret = -ERANGE; |
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goto err; |
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} |
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name_ptr = (unsigned long)(di + 1); read_extent_buffer(leaf, buffer, name_ptr, name_len); buffer[name_len] = '\0'; size_left -= name_len + 1; buffer += name_len + 1; |
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next: path->slots[0]++; |
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} ret = total_size; err: |
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btrfs_free_path(path); return ret; } /* |
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* List of handlers for synthetic system.* attributes. All real ondisk * attributes are handled directly. */ |
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const struct xattr_handler *btrfs_xattr_handlers[] = { |
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#ifdef CONFIG_BTRFS_FS_POSIX_ACL |
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&btrfs_xattr_acl_access_handler, &btrfs_xattr_acl_default_handler, #endif NULL, }; /* * Check if the attribute is in a supported namespace. * * This applied after the check for the synthetic attributes in the system * namespace. |
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*/ |
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static bool btrfs_is_valid_xattr(const char *name) { |
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return !strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN) || |
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!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN) || !strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN) || !strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN); |
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} |
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ssize_t btrfs_getxattr(struct dentry *dentry, const char *name, void *buffer, size_t size) { /* * If this is a request for a synthetic attribute in the system.* * namespace use the generic infrastructure to resolve a handler * for it via sb->s_xattr. */ if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN)) return generic_getxattr(dentry, name, buffer, size); |
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if (!btrfs_is_valid_xattr(name)) return -EOPNOTSUPP; return __btrfs_getxattr(dentry->d_inode, name, buffer, size); } |
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int btrfs_setxattr(struct dentry *dentry, const char *name, const void *value, size_t size, int flags) { |
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struct btrfs_root *root = BTRFS_I(dentry->d_inode)->root; /* * The permission on security.* and system.* is not checked * in permission(). */ if (btrfs_root_readonly(root)) return -EROFS; |
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/* * If this is a request for a synthetic attribute in the system.* * namespace use the generic infrastructure to resolve a handler * for it via sb->s_xattr. */ if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN)) return generic_setxattr(dentry, name, value, size, flags); |
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if (!btrfs_is_valid_xattr(name)) return -EOPNOTSUPP; |
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if (size == 0) value = ""; /* empty EA, do not remove */ |
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return __btrfs_setxattr(NULL, dentry->d_inode, name, value, size, flags); |
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} int btrfs_removexattr(struct dentry *dentry, const char *name) { |
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struct btrfs_root *root = BTRFS_I(dentry->d_inode)->root; /* * The permission on security.* and system.* is not checked * in permission(). */ if (btrfs_root_readonly(root)) return -EROFS; |
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/* * If this is a request for a synthetic attribute in the system.* * namespace use the generic infrastructure to resolve a handler * for it via sb->s_xattr. */ if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN)) return generic_removexattr(dentry, name); if (!btrfs_is_valid_xattr(name)) return -EOPNOTSUPP; |
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return __btrfs_setxattr(NULL, dentry->d_inode, name, NULL, 0, XATTR_REPLACE); |
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} |
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int btrfs_initxattrs(struct inode *inode, const struct xattr *xattr_array, void *fs_info) |
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{ |
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const struct xattr *xattr; struct btrfs_trans_handle *trans = fs_info; |
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char *name; |
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int err = 0; |
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for (xattr = xattr_array; xattr->name != NULL; xattr++) { name = kmalloc(XATTR_SECURITY_PREFIX_LEN + strlen(xattr->name) + 1, GFP_NOFS); if (!name) { err = -ENOMEM; break; } |
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strcpy(name, XATTR_SECURITY_PREFIX); |
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strcpy(name + XATTR_SECURITY_PREFIX_LEN, xattr->name); err = __btrfs_setxattr(trans, inode, name, xattr->value, xattr->value_len, 0); |
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kfree(name); |
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if (err < 0) break; |
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} |
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return err; } |
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int btrfs_xattr_security_init(struct btrfs_trans_handle *trans, struct inode *inode, struct inode *dir, const struct qstr *qstr) { return security_inode_init_security(inode, dir, qstr, &btrfs_initxattrs, trans); } |