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-rw-r--r--fs/btrfs/xattr.c492
1 files changed, 492 insertions, 0 deletions
diff --git a/fs/btrfs/xattr.c b/fs/btrfs/xattr.c
new file mode 100644
index 000000000..5bb8d8c86
--- /dev/null
+++ b/fs/btrfs/xattr.c
@@ -0,0 +1,492 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2007 Red Hat. All rights reserved.
+ */
+
+#include <linux/init.h>
+#include <linux/fs.h>
+#include <linux/slab.h>
+#include <linux/rwsem.h>
+#include <linux/xattr.h>
+#include <linux/security.h>
+#include <linux/posix_acl_xattr.h>
+#include <linux/iversion.h>
+#include <linux/sched/mm.h>
+#include "ctree.h"
+#include "btrfs_inode.h"
+#include "transaction.h"
+#include "xattr.h"
+#include "disk-io.h"
+#include "props.h"
+#include "locking.h"
+
+int btrfs_getxattr(struct inode *inode, const char *name,
+ void *buffer, size_t size)
+{
+ struct btrfs_dir_item *di;
+ struct btrfs_root *root = BTRFS_I(inode)->root;
+ struct btrfs_path *path;
+ struct extent_buffer *leaf;
+ int ret = 0;
+ unsigned long data_ptr;
+
+ path = btrfs_alloc_path();
+ if (!path)
+ return -ENOMEM;
+
+ /* lookup the xattr by name */
+ di = btrfs_lookup_xattr(NULL, root, path, btrfs_ino(BTRFS_I(inode)),
+ name, strlen(name), 0);
+ if (!di) {
+ ret = -ENODATA;
+ goto out;
+ } else if (IS_ERR(di)) {
+ ret = PTR_ERR(di);
+ goto out;
+ }
+
+ 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;
+ }
+
+ /*
+ * 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
+ */
+ data_ptr = (unsigned long)((char *)(di + 1) +
+ btrfs_dir_name_len(leaf, di));
+ read_extent_buffer(leaf, buffer, data_ptr,
+ btrfs_dir_data_len(leaf, di));
+ ret = btrfs_dir_data_len(leaf, di);
+
+out:
+ btrfs_free_path(path);
+ return ret;
+}
+
+int btrfs_setxattr(struct btrfs_trans_handle *trans, struct inode *inode,
+ const char *name, const void *value, size_t size, int flags)
+{
+ struct btrfs_dir_item *di = NULL;
+ struct btrfs_root *root = BTRFS_I(inode)->root;
+ struct btrfs_fs_info *fs_info = root->fs_info;
+ struct btrfs_path *path;
+ size_t name_len = strlen(name);
+ int ret = 0;
+
+ ASSERT(trans);
+
+ if (name_len + size > BTRFS_MAX_XATTR_SIZE(root->fs_info))
+ return -ENOSPC;
+
+ path = btrfs_alloc_path();
+ if (!path)
+ return -ENOMEM;
+ path->skip_release_on_error = 1;
+
+ if (!value) {
+ di = btrfs_lookup_xattr(trans, root, path,
+ btrfs_ino(BTRFS_I(inode)), name, name_len, -1);
+ if (!di && (flags & XATTR_REPLACE))
+ ret = -ENODATA;
+ else if (IS_ERR(di))
+ ret = PTR_ERR(di);
+ else if (di)
+ ret = btrfs_delete_one_dir_name(trans, root, path, di);
+ goto out;
+ }
+
+ /*
+ * For a replace we can't just do the insert blindly.
+ * Do a lookup first (read-only btrfs_search_slot), and return if xattr
+ * doesn't exist. If it exists, fall down below to the insert/replace
+ * path - we can't race with a concurrent xattr delete, because the VFS
+ * locks the inode's i_mutex before calling setxattr or removexattr.
+ */
+ if (flags & XATTR_REPLACE) {
+ ASSERT(inode_is_locked(inode));
+ di = btrfs_lookup_xattr(NULL, root, path,
+ btrfs_ino(BTRFS_I(inode)), name, name_len, 0);
+ if (!di)
+ ret = -ENODATA;
+ else if (IS_ERR(di))
+ ret = PTR_ERR(di);
+ if (ret)
+ goto out;
+ btrfs_release_path(path);
+ di = NULL;
+ }
+
+ ret = btrfs_insert_xattr_item(trans, root, path, btrfs_ino(BTRFS_I(inode)),
+ name, name_len, value, size);
+ if (ret == -EOVERFLOW) {
+ /*
+ * We have an existing item in a leaf, split_leaf couldn't
+ * expand it. That item might have or not a dir_item that
+ * matches our target xattr, so lets check.
+ */
+ ret = 0;
+ btrfs_assert_tree_write_locked(path->nodes[0]);
+ di = btrfs_match_dir_item_name(fs_info, path, name, name_len);
+ if (!di && !(flags & XATTR_REPLACE)) {
+ ret = -ENOSPC;
+ goto out;
+ }
+ } else if (ret == -EEXIST) {
+ ret = 0;
+ di = btrfs_match_dir_item_name(fs_info, path, name, name_len);
+ ASSERT(di); /* logic error */
+ } else if (ret) {
+ goto out;
+ }
+
+ if (di && (flags & XATTR_CREATE)) {
+ ret = -EEXIST;
+ goto out;
+ }
+
+ if (di) {
+ /*
+ * We're doing a replace, and it must be atomic, that is, at
+ * any point in time we have either the old or the new xattr
+ * value in the tree. We don't want readers (getxattr and
+ * listxattrs) to miss a value, this is specially important
+ * for ACLs.
+ */
+ const int slot = path->slots[0];
+ struct extent_buffer *leaf = path->nodes[0];
+ const u16 old_data_len = btrfs_dir_data_len(leaf, di);
+ const u32 item_size = btrfs_item_size(leaf, slot);
+ const u32 data_size = sizeof(*di) + name_len + size;
+ unsigned long data_ptr;
+ char *ptr;
+
+ if (size > old_data_len) {
+ if (btrfs_leaf_free_space(leaf) <
+ (size - old_data_len)) {
+ ret = -ENOSPC;
+ goto out;
+ }
+ }
+
+ if (old_data_len + name_len + sizeof(*di) == item_size) {
+ /* No other xattrs packed in the same leaf item. */
+ if (size > old_data_len)
+ btrfs_extend_item(path, size - old_data_len);
+ else if (size < old_data_len)
+ btrfs_truncate_item(path, data_size, 1);
+ } else {
+ /* There are other xattrs packed in the same item. */
+ ret = btrfs_delete_one_dir_name(trans, root, path, di);
+ if (ret)
+ goto out;
+ btrfs_extend_item(path, data_size);
+ }
+
+ ptr = btrfs_item_ptr(leaf, slot, char);
+ ptr += btrfs_item_size(leaf, slot) - data_size;
+ di = (struct btrfs_dir_item *)ptr;
+ btrfs_set_dir_data_len(leaf, di, size);
+ data_ptr = ((unsigned long)(di + 1)) + name_len;
+ write_extent_buffer(leaf, value, data_ptr, size);
+ btrfs_mark_buffer_dirty(leaf);
+ } else {
+ /*
+ * Insert, and we had space for the xattr, so path->slots[0] is
+ * where our xattr dir_item is and btrfs_insert_xattr_item()
+ * filled it.
+ */
+ }
+out:
+ btrfs_free_path(path);
+ if (!ret) {
+ set_bit(BTRFS_INODE_COPY_EVERYTHING,
+ &BTRFS_I(inode)->runtime_flags);
+ clear_bit(BTRFS_INODE_NO_XATTRS, &BTRFS_I(inode)->runtime_flags);
+ }
+ return ret;
+}
+
+/*
+ * @value: "" makes the attribute to empty, NULL removes it
+ */
+int btrfs_setxattr_trans(struct inode *inode, const char *name,
+ const void *value, size_t size, int flags)
+{
+ struct btrfs_root *root = BTRFS_I(inode)->root;
+ struct btrfs_trans_handle *trans;
+ const bool start_trans = (current->journal_info == NULL);
+ int ret;
+
+ if (start_trans) {
+ /*
+ * 1 unit for inserting/updating/deleting the xattr
+ * 1 unit for the inode item update
+ */
+ trans = btrfs_start_transaction(root, 2);
+ if (IS_ERR(trans))
+ return PTR_ERR(trans);
+ } else {
+ /*
+ * This can happen when smack is enabled and a directory is being
+ * created. It happens through d_instantiate_new(), which calls
+ * smack_d_instantiate(), which in turn calls __vfs_setxattr() to
+ * set the transmute xattr (XATTR_NAME_SMACKTRANSMUTE) on the
+ * inode. We have already reserved space for the xattr and inode
+ * update at btrfs_mkdir(), so just use the transaction handle.
+ * We don't join or start a transaction, as that will reset the
+ * block_rsv of the handle and trigger a warning for the start
+ * case.
+ */
+ ASSERT(strncmp(name, XATTR_SECURITY_PREFIX,
+ XATTR_SECURITY_PREFIX_LEN) == 0);
+ trans = current->journal_info;
+ }
+
+ ret = btrfs_setxattr(trans, inode, name, value, size, flags);
+ if (ret)
+ goto out;
+
+ inode_inc_iversion(inode);
+ inode->i_ctime = current_time(inode);
+ ret = btrfs_update_inode(trans, root, BTRFS_I(inode));
+ if (ret)
+ btrfs_abort_transaction(trans, ret);
+out:
+ if (start_trans)
+ btrfs_end_transaction(trans);
+ return ret;
+}
+
+ssize_t btrfs_listxattr(struct dentry *dentry, char *buffer, size_t size)
+{
+ struct btrfs_key found_key;
+ struct btrfs_key key;
+ struct inode *inode = d_inode(dentry);
+ struct btrfs_root *root = BTRFS_I(inode)->root;
+ struct btrfs_path *path;
+ int iter_ret = 0;
+ int ret = 0;
+ size_t total_size = 0, size_left = size;
+
+ /*
+ * 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
+ */
+ key.objectid = btrfs_ino(BTRFS_I(inode));
+ key.type = BTRFS_XATTR_ITEM_KEY;
+ key.offset = 0;
+
+ path = btrfs_alloc_path();
+ if (!path)
+ return -ENOMEM;
+ path->reada = READA_FORWARD;
+
+ /* search for our xattrs */
+ btrfs_for_each_slot(root, &key, &found_key, path, iter_ret) {
+ struct extent_buffer *leaf;
+ int slot;
+ struct btrfs_dir_item *di;
+ u32 item_size;
+ u32 cur;
+
+ leaf = path->nodes[0];
+ slot = path->slots[0];
+
+ /* check to make sure this item is what we want */
+ if (found_key.objectid != key.objectid)
+ break;
+ if (found_key.type > BTRFS_XATTR_ITEM_KEY)
+ break;
+ if (found_key.type < BTRFS_XATTR_ITEM_KEY)
+ continue;
+
+ di = btrfs_item_ptr(leaf, slot, struct btrfs_dir_item);
+ item_size = btrfs_item_size(leaf, slot);
+ cur = 0;
+ while (cur < item_size) {
+ u16 name_len = btrfs_dir_name_len(leaf, di);
+ u16 data_len = btrfs_dir_data_len(leaf, di);
+ u32 this_len = sizeof(*di) + name_len + data_len;
+ unsigned long name_ptr = (unsigned long)(di + 1);
+
+ total_size += name_len + 1;
+ /*
+ * We are just looking for how big our buffer needs to
+ * be.
+ */
+ if (!size)
+ goto next;
+
+ if (!buffer || (name_len + 1) > size_left) {
+ iter_ret = -ERANGE;
+ break;
+ }
+
+ read_extent_buffer(leaf, buffer, name_ptr, name_len);
+ buffer[name_len] = '\0';
+
+ size_left -= name_len + 1;
+ buffer += name_len + 1;
+next:
+ cur += this_len;
+ di = (struct btrfs_dir_item *)((char *)di + this_len);
+ }
+ }
+
+ if (iter_ret < 0)
+ ret = iter_ret;
+ else
+ ret = total_size;
+
+ btrfs_free_path(path);
+
+ return ret;
+}
+
+static int btrfs_xattr_handler_get(const struct xattr_handler *handler,
+ struct dentry *unused, struct inode *inode,
+ const char *name, void *buffer, size_t size)
+{
+ name = xattr_full_name(handler, name);
+ return btrfs_getxattr(inode, name, buffer, size);
+}
+
+static int btrfs_xattr_handler_set(const struct xattr_handler *handler,
+ struct user_namespace *mnt_userns,
+ struct dentry *unused, struct inode *inode,
+ const char *name, const void *buffer,
+ size_t size, int flags)
+{
+ if (btrfs_root_readonly(BTRFS_I(inode)->root))
+ return -EROFS;
+
+ name = xattr_full_name(handler, name);
+ return btrfs_setxattr_trans(inode, name, buffer, size, flags);
+}
+
+static int btrfs_xattr_handler_set_prop(const struct xattr_handler *handler,
+ struct user_namespace *mnt_userns,
+ struct dentry *unused, struct inode *inode,
+ const char *name, const void *value,
+ size_t size, int flags)
+{
+ int ret;
+ struct btrfs_trans_handle *trans;
+ struct btrfs_root *root = BTRFS_I(inode)->root;
+
+ name = xattr_full_name(handler, name);
+ ret = btrfs_validate_prop(BTRFS_I(inode), name, value, size);
+ if (ret)
+ return ret;
+
+ if (btrfs_ignore_prop(BTRFS_I(inode), name))
+ return 0;
+
+ trans = btrfs_start_transaction(root, 2);
+ if (IS_ERR(trans))
+ return PTR_ERR(trans);
+
+ ret = btrfs_set_prop(trans, inode, name, value, size, flags);
+ if (!ret) {
+ inode_inc_iversion(inode);
+ inode->i_ctime = current_time(inode);
+ ret = btrfs_update_inode(trans, root, BTRFS_I(inode));
+ if (ret)
+ btrfs_abort_transaction(trans, ret);
+ }
+
+ btrfs_end_transaction(trans);
+
+ return ret;
+}
+
+static const struct xattr_handler btrfs_security_xattr_handler = {
+ .prefix = XATTR_SECURITY_PREFIX,
+ .get = btrfs_xattr_handler_get,
+ .set = btrfs_xattr_handler_set,
+};
+
+static const struct xattr_handler btrfs_trusted_xattr_handler = {
+ .prefix = XATTR_TRUSTED_PREFIX,
+ .get = btrfs_xattr_handler_get,
+ .set = btrfs_xattr_handler_set,
+};
+
+static const struct xattr_handler btrfs_user_xattr_handler = {
+ .prefix = XATTR_USER_PREFIX,
+ .get = btrfs_xattr_handler_get,
+ .set = btrfs_xattr_handler_set,
+};
+
+static const struct xattr_handler btrfs_btrfs_xattr_handler = {
+ .prefix = XATTR_BTRFS_PREFIX,
+ .get = btrfs_xattr_handler_get,
+ .set = btrfs_xattr_handler_set_prop,
+};
+
+const struct xattr_handler *btrfs_xattr_handlers[] = {
+ &btrfs_security_xattr_handler,
+#ifdef CONFIG_BTRFS_FS_POSIX_ACL
+ &posix_acl_access_xattr_handler,
+ &posix_acl_default_xattr_handler,
+#endif
+ &btrfs_trusted_xattr_handler,
+ &btrfs_user_xattr_handler,
+ &btrfs_btrfs_xattr_handler,
+ NULL,
+};
+
+static int btrfs_initxattrs(struct inode *inode,
+ const struct xattr *xattr_array, void *fs_private)
+{
+ struct btrfs_trans_handle *trans = fs_private;
+ const struct xattr *xattr;
+ unsigned int nofs_flag;
+ char *name;
+ int err = 0;
+
+ /*
+ * We're holding a transaction handle, so use a NOFS memory allocation
+ * context to avoid deadlock if reclaim happens.
+ */
+ nofs_flag = memalloc_nofs_save();
+ for (xattr = xattr_array; xattr->name != NULL; xattr++) {
+ name = kmalloc(XATTR_SECURITY_PREFIX_LEN +
+ strlen(xattr->name) + 1, GFP_KERNEL);
+ if (!name) {
+ err = -ENOMEM;
+ break;
+ }
+ strcpy(name, XATTR_SECURITY_PREFIX);
+ strcpy(name + XATTR_SECURITY_PREFIX_LEN, xattr->name);
+ err = btrfs_setxattr(trans, inode, name, xattr->value,
+ xattr->value_len, 0);
+ kfree(name);
+ if (err < 0)
+ break;
+ }
+ memalloc_nofs_restore(nofs_flag);
+ return err;
+}
+
+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);
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-06-08 14:21:50 +0000