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-rw-r--r--fs/kernfs/inode.c446
1 files changed, 446 insertions, 0 deletions
diff --git a/fs/kernfs/inode.c b/fs/kernfs/inode.c
new file mode 100644
index 000000000..3d783d80f
--- /dev/null
+++ b/fs/kernfs/inode.c
@@ -0,0 +1,446 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * fs/kernfs/inode.c - kernfs inode implementation
+ *
+ * Copyright (c) 2001-3 Patrick Mochel
+ * Copyright (c) 2007 SUSE Linux Products GmbH
+ * Copyright (c) 2007, 2013 Tejun Heo <tj@kernel.org>
+ */
+
+#include <linux/pagemap.h>
+#include <linux/backing-dev.h>
+#include <linux/capability.h>
+#include <linux/errno.h>
+#include <linux/slab.h>
+#include <linux/xattr.h>
+#include <linux/security.h>
+
+#include "kernfs-internal.h"
+
+static const struct inode_operations kernfs_iops = {
+ .permission = kernfs_iop_permission,
+ .setattr = kernfs_iop_setattr,
+ .getattr = kernfs_iop_getattr,
+ .listxattr = kernfs_iop_listxattr,
+};
+
+static struct kernfs_iattrs *__kernfs_iattrs(struct kernfs_node *kn, int alloc)
+{
+ static DEFINE_MUTEX(iattr_mutex);
+ struct kernfs_iattrs *ret;
+
+ mutex_lock(&iattr_mutex);
+
+ if (kn->iattr || !alloc)
+ goto out_unlock;
+
+ kn->iattr = kmem_cache_zalloc(kernfs_iattrs_cache, GFP_KERNEL);
+ if (!kn->iattr)
+ goto out_unlock;
+
+ /* assign default attributes */
+ kn->iattr->ia_uid = GLOBAL_ROOT_UID;
+ kn->iattr->ia_gid = GLOBAL_ROOT_GID;
+
+ ktime_get_real_ts64(&kn->iattr->ia_atime);
+ kn->iattr->ia_mtime = kn->iattr->ia_atime;
+ kn->iattr->ia_ctime = kn->iattr->ia_atime;
+
+ simple_xattrs_init(&kn->iattr->xattrs);
+ atomic_set(&kn->iattr->nr_user_xattrs, 0);
+ atomic_set(&kn->iattr->user_xattr_size, 0);
+out_unlock:
+ ret = kn->iattr;
+ mutex_unlock(&iattr_mutex);
+ return ret;
+}
+
+static struct kernfs_iattrs *kernfs_iattrs(struct kernfs_node *kn)
+{
+ return __kernfs_iattrs(kn, 1);
+}
+
+static struct kernfs_iattrs *kernfs_iattrs_noalloc(struct kernfs_node *kn)
+{
+ return __kernfs_iattrs(kn, 0);
+}
+
+int __kernfs_setattr(struct kernfs_node *kn, const struct iattr *iattr)
+{
+ struct kernfs_iattrs *attrs;
+ unsigned int ia_valid = iattr->ia_valid;
+
+ attrs = kernfs_iattrs(kn);
+ if (!attrs)
+ return -ENOMEM;
+
+ if (ia_valid & ATTR_UID)
+ attrs->ia_uid = iattr->ia_uid;
+ if (ia_valid & ATTR_GID)
+ attrs->ia_gid = iattr->ia_gid;
+ if (ia_valid & ATTR_ATIME)
+ attrs->ia_atime = iattr->ia_atime;
+ if (ia_valid & ATTR_MTIME)
+ attrs->ia_mtime = iattr->ia_mtime;
+ if (ia_valid & ATTR_CTIME)
+ attrs->ia_ctime = iattr->ia_ctime;
+ if (ia_valid & ATTR_MODE)
+ kn->mode = iattr->ia_mode;
+ return 0;
+}
+
+/**
+ * kernfs_setattr - set iattr on a node
+ * @kn: target node
+ * @iattr: iattr to set
+ *
+ * Returns 0 on success, -errno on failure.
+ */
+int kernfs_setattr(struct kernfs_node *kn, const struct iattr *iattr)
+{
+ int ret;
+ struct kernfs_root *root = kernfs_root(kn);
+
+ down_write(&root->kernfs_rwsem);
+ ret = __kernfs_setattr(kn, iattr);
+ up_write(&root->kernfs_rwsem);
+ return ret;
+}
+
+int kernfs_iop_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
+ struct iattr *iattr)
+{
+ struct inode *inode = d_inode(dentry);
+ struct kernfs_node *kn = inode->i_private;
+ struct kernfs_root *root;
+ int error;
+
+ if (!kn)
+ return -EINVAL;
+
+ root = kernfs_root(kn);
+ down_write(&root->kernfs_rwsem);
+ error = setattr_prepare(&init_user_ns, dentry, iattr);
+ if (error)
+ goto out;
+
+ error = __kernfs_setattr(kn, iattr);
+ if (error)
+ goto out;
+
+ /* this ignores size changes */
+ setattr_copy(&init_user_ns, inode, iattr);
+
+out:
+ up_write(&root->kernfs_rwsem);
+ return error;
+}
+
+ssize_t kernfs_iop_listxattr(struct dentry *dentry, char *buf, size_t size)
+{
+ struct kernfs_node *kn = kernfs_dentry_node(dentry);
+ struct kernfs_iattrs *attrs;
+
+ attrs = kernfs_iattrs(kn);
+ if (!attrs)
+ return -ENOMEM;
+
+ return simple_xattr_list(d_inode(dentry), &attrs->xattrs, buf, size);
+}
+
+static inline void set_default_inode_attr(struct inode *inode, umode_t mode)
+{
+ inode->i_mode = mode;
+ inode->i_atime = inode->i_mtime =
+ inode->i_ctime = current_time(inode);
+}
+
+static inline void set_inode_attr(struct inode *inode,
+ struct kernfs_iattrs *attrs)
+{
+ inode->i_uid = attrs->ia_uid;
+ inode->i_gid = attrs->ia_gid;
+ inode->i_atime = attrs->ia_atime;
+ inode->i_mtime = attrs->ia_mtime;
+ inode->i_ctime = attrs->ia_ctime;
+}
+
+static void kernfs_refresh_inode(struct kernfs_node *kn, struct inode *inode)
+{
+ struct kernfs_iattrs *attrs = kn->iattr;
+
+ inode->i_mode = kn->mode;
+ if (attrs)
+ /*
+ * kernfs_node has non-default attributes get them from
+ * persistent copy in kernfs_node.
+ */
+ set_inode_attr(inode, attrs);
+
+ if (kernfs_type(kn) == KERNFS_DIR)
+ set_nlink(inode, kn->dir.subdirs + 2);
+}
+
+int kernfs_iop_getattr(struct user_namespace *mnt_userns,
+ const struct path *path, struct kstat *stat,
+ u32 request_mask, unsigned int query_flags)
+{
+ struct inode *inode = d_inode(path->dentry);
+ struct kernfs_node *kn = inode->i_private;
+ struct kernfs_root *root = kernfs_root(kn);
+
+ down_read(&root->kernfs_rwsem);
+ spin_lock(&inode->i_lock);
+ kernfs_refresh_inode(kn, inode);
+ generic_fillattr(&init_user_ns, inode, stat);
+ spin_unlock(&inode->i_lock);
+ up_read(&root->kernfs_rwsem);
+
+ return 0;
+}
+
+static void kernfs_init_inode(struct kernfs_node *kn, struct inode *inode)
+{
+ kernfs_get(kn);
+ inode->i_private = kn;
+ inode->i_mapping->a_ops = &ram_aops;
+ inode->i_op = &kernfs_iops;
+ inode->i_generation = kernfs_gen(kn);
+
+ set_default_inode_attr(inode, kn->mode);
+ kernfs_refresh_inode(kn, inode);
+
+ /* initialize inode according to type */
+ switch (kernfs_type(kn)) {
+ case KERNFS_DIR:
+ inode->i_op = &kernfs_dir_iops;
+ inode->i_fop = &kernfs_dir_fops;
+ if (kn->flags & KERNFS_EMPTY_DIR)
+ make_empty_dir_inode(inode);
+ break;
+ case KERNFS_FILE:
+ inode->i_size = kn->attr.size;
+ inode->i_fop = &kernfs_file_fops;
+ break;
+ case KERNFS_LINK:
+ inode->i_op = &kernfs_symlink_iops;
+ break;
+ default:
+ BUG();
+ }
+
+ unlock_new_inode(inode);
+}
+
+/**
+ * kernfs_get_inode - get inode for kernfs_node
+ * @sb: super block
+ * @kn: kernfs_node to allocate inode for
+ *
+ * Get inode for @kn. If such inode doesn't exist, a new inode is
+ * allocated and basics are initialized. New inode is returned
+ * locked.
+ *
+ * LOCKING:
+ * Kernel thread context (may sleep).
+ *
+ * RETURNS:
+ * Pointer to allocated inode on success, NULL on failure.
+ */
+struct inode *kernfs_get_inode(struct super_block *sb, struct kernfs_node *kn)
+{
+ struct inode *inode;
+
+ inode = iget_locked(sb, kernfs_ino(kn));
+ if (inode && (inode->i_state & I_NEW))
+ kernfs_init_inode(kn, inode);
+
+ return inode;
+}
+
+/*
+ * The kernfs_node serves as both an inode and a directory entry for
+ * kernfs. To prevent the kernfs inode numbers from being freed
+ * prematurely we take a reference to kernfs_node from the kernfs inode. A
+ * super_operations.evict_inode() implementation is needed to drop that
+ * reference upon inode destruction.
+ */
+void kernfs_evict_inode(struct inode *inode)
+{
+ struct kernfs_node *kn = inode->i_private;
+
+ truncate_inode_pages_final(&inode->i_data);
+ clear_inode(inode);
+ kernfs_put(kn);
+}
+
+int kernfs_iop_permission(struct user_namespace *mnt_userns,
+ struct inode *inode, int mask)
+{
+ struct kernfs_node *kn;
+ struct kernfs_root *root;
+ int ret;
+
+ if (mask & MAY_NOT_BLOCK)
+ return -ECHILD;
+
+ kn = inode->i_private;
+ root = kernfs_root(kn);
+
+ down_read(&root->kernfs_rwsem);
+ spin_lock(&inode->i_lock);
+ kernfs_refresh_inode(kn, inode);
+ ret = generic_permission(&init_user_ns, inode, mask);
+ spin_unlock(&inode->i_lock);
+ up_read(&root->kernfs_rwsem);
+
+ return ret;
+}
+
+int kernfs_xattr_get(struct kernfs_node *kn, const char *name,
+ void *value, size_t size)
+{
+ struct kernfs_iattrs *attrs = kernfs_iattrs_noalloc(kn);
+ if (!attrs)
+ return -ENODATA;
+
+ return simple_xattr_get(&attrs->xattrs, name, value, size);
+}
+
+int kernfs_xattr_set(struct kernfs_node *kn, const char *name,
+ const void *value, size_t size, int flags)
+{
+ struct kernfs_iattrs *attrs = kernfs_iattrs(kn);
+ if (!attrs)
+ return -ENOMEM;
+
+ return simple_xattr_set(&attrs->xattrs, name, value, size, flags, NULL);
+}
+
+static int kernfs_vfs_xattr_get(const struct xattr_handler *handler,
+ struct dentry *unused, struct inode *inode,
+ const char *suffix, void *value, size_t size)
+{
+ const char *name = xattr_full_name(handler, suffix);
+ struct kernfs_node *kn = inode->i_private;
+
+ return kernfs_xattr_get(kn, name, value, size);
+}
+
+static int kernfs_vfs_xattr_set(const struct xattr_handler *handler,
+ struct user_namespace *mnt_userns,
+ struct dentry *unused, struct inode *inode,
+ const char *suffix, const void *value,
+ size_t size, int flags)
+{
+ const char *name = xattr_full_name(handler, suffix);
+ struct kernfs_node *kn = inode->i_private;
+
+ return kernfs_xattr_set(kn, name, value, size, flags);
+}
+
+static int kernfs_vfs_user_xattr_add(struct kernfs_node *kn,
+ const char *full_name,
+ struct simple_xattrs *xattrs,
+ const void *value, size_t size, int flags)
+{
+ atomic_t *sz = &kn->iattr->user_xattr_size;
+ atomic_t *nr = &kn->iattr->nr_user_xattrs;
+ ssize_t removed_size;
+ int ret;
+
+ if (atomic_inc_return(nr) > KERNFS_MAX_USER_XATTRS) {
+ ret = -ENOSPC;
+ goto dec_count_out;
+ }
+
+ if (atomic_add_return(size, sz) > KERNFS_USER_XATTR_SIZE_LIMIT) {
+ ret = -ENOSPC;
+ goto dec_size_out;
+ }
+
+ ret = simple_xattr_set(xattrs, full_name, value, size, flags,
+ &removed_size);
+
+ if (!ret && removed_size >= 0)
+ size = removed_size;
+ else if (!ret)
+ return 0;
+dec_size_out:
+ atomic_sub(size, sz);
+dec_count_out:
+ atomic_dec(nr);
+ return ret;
+}
+
+static int kernfs_vfs_user_xattr_rm(struct kernfs_node *kn,
+ const char *full_name,
+ struct simple_xattrs *xattrs,
+ const void *value, size_t size, int flags)
+{
+ atomic_t *sz = &kn->iattr->user_xattr_size;
+ atomic_t *nr = &kn->iattr->nr_user_xattrs;
+ ssize_t removed_size;
+ int ret;
+
+ ret = simple_xattr_set(xattrs, full_name, value, size, flags,
+ &removed_size);
+
+ if (removed_size >= 0) {
+ atomic_sub(removed_size, sz);
+ atomic_dec(nr);
+ }
+
+ return ret;
+}
+
+static int kernfs_vfs_user_xattr_set(const struct xattr_handler *handler,
+ struct user_namespace *mnt_userns,
+ struct dentry *unused, struct inode *inode,
+ const char *suffix, const void *value,
+ size_t size, int flags)
+{
+ const char *full_name = xattr_full_name(handler, suffix);
+ struct kernfs_node *kn = inode->i_private;
+ struct kernfs_iattrs *attrs;
+
+ if (!(kernfs_root(kn)->flags & KERNFS_ROOT_SUPPORT_USER_XATTR))
+ return -EOPNOTSUPP;
+
+ attrs = kernfs_iattrs(kn);
+ if (!attrs)
+ return -ENOMEM;
+
+ if (value)
+ return kernfs_vfs_user_xattr_add(kn, full_name, &attrs->xattrs,
+ value, size, flags);
+ else
+ return kernfs_vfs_user_xattr_rm(kn, full_name, &attrs->xattrs,
+ value, size, flags);
+
+}
+
+static const struct xattr_handler kernfs_trusted_xattr_handler = {
+ .prefix = XATTR_TRUSTED_PREFIX,
+ .get = kernfs_vfs_xattr_get,
+ .set = kernfs_vfs_xattr_set,
+};
+
+static const struct xattr_handler kernfs_security_xattr_handler = {
+ .prefix = XATTR_SECURITY_PREFIX,
+ .get = kernfs_vfs_xattr_get,
+ .set = kernfs_vfs_xattr_set,
+};
+
+static const struct xattr_handler kernfs_user_xattr_handler = {
+ .prefix = XATTR_USER_PREFIX,
+ .get = kernfs_vfs_xattr_get,
+ .set = kernfs_vfs_user_xattr_set,
+};
+
+const struct xattr_handler *kernfs_xattr_handlers[] = {
+ &kernfs_trusted_xattr_handler,
+ &kernfs_security_xattr_handler,
+ &kernfs_user_xattr_handler,
+ NULL
+};