summaryrefslogtreecommitdiffstats
path: root/fs/sysfs/symlink.c
diff options
context:
space:
mode:
Diffstat (limited to '')
-rw-r--r--fs/sysfs/symlink.c198
1 files changed, 198 insertions, 0 deletions
diff --git a/fs/sysfs/symlink.c b/fs/sysfs/symlink.c
new file mode 100644
index 000000000..5603530a1
--- /dev/null
+++ b/fs/sysfs/symlink.c
@@ -0,0 +1,198 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * fs/sysfs/symlink.c - sysfs symlink implementation
+ *
+ * Copyright (c) 2001-3 Patrick Mochel
+ * Copyright (c) 2007 SUSE Linux Products GmbH
+ * Copyright (c) 2007 Tejun Heo <teheo@suse.de>
+ *
+ * Please see Documentation/filesystems/sysfs.rst for more information.
+ */
+
+#include <linux/fs.h>
+#include <linux/module.h>
+#include <linux/kobject.h>
+#include <linux/mutex.h>
+#include <linux/security.h>
+
+#include "sysfs.h"
+
+static int sysfs_do_create_link_sd(struct kernfs_node *parent,
+ struct kobject *target_kobj,
+ const char *name, int warn)
+{
+ struct kernfs_node *kn, *target = NULL;
+
+ if (WARN_ON(!name || !parent))
+ return -EINVAL;
+
+ /*
+ * We don't own @target_kobj and it may be removed at any time.
+ * Synchronize using sysfs_symlink_target_lock. See
+ * sysfs_remove_dir() for details.
+ */
+ spin_lock(&sysfs_symlink_target_lock);
+ if (target_kobj->sd) {
+ target = target_kobj->sd;
+ kernfs_get(target);
+ }
+ spin_unlock(&sysfs_symlink_target_lock);
+
+ if (!target)
+ return -ENOENT;
+
+ kn = kernfs_create_link(parent, name, target);
+ kernfs_put(target);
+
+ if (!IS_ERR(kn))
+ return 0;
+
+ if (warn && PTR_ERR(kn) == -EEXIST)
+ sysfs_warn_dup(parent, name);
+ return PTR_ERR(kn);
+}
+
+/**
+ * sysfs_create_link_sd - create symlink to a given object.
+ * @kn: directory we're creating the link in.
+ * @target: object we're pointing to.
+ * @name: name of the symlink.
+ */
+int sysfs_create_link_sd(struct kernfs_node *kn, struct kobject *target,
+ const char *name)
+{
+ return sysfs_do_create_link_sd(kn, target, name, 1);
+}
+
+static int sysfs_do_create_link(struct kobject *kobj, struct kobject *target,
+ const char *name, int warn)
+{
+ struct kernfs_node *parent = NULL;
+
+ if (!kobj)
+ parent = sysfs_root_kn;
+ else
+ parent = kobj->sd;
+
+ if (!parent)
+ return -EFAULT;
+
+ return sysfs_do_create_link_sd(parent, target, name, warn);
+}
+
+/**
+ * sysfs_create_link - create symlink between two objects.
+ * @kobj: object whose directory we're creating the link in.
+ * @target: object we're pointing to.
+ * @name: name of the symlink.
+ */
+int sysfs_create_link(struct kobject *kobj, struct kobject *target,
+ const char *name)
+{
+ return sysfs_do_create_link(kobj, target, name, 1);
+}
+EXPORT_SYMBOL_GPL(sysfs_create_link);
+
+/**
+ * sysfs_create_link_nowarn - create symlink between two objects.
+ * @kobj: object whose directory we're creating the link in.
+ * @target: object we're pointing to.
+ * @name: name of the symlink.
+ *
+ * This function does the same as sysfs_create_link(), but it
+ * doesn't warn if the link already exists.
+ */
+int sysfs_create_link_nowarn(struct kobject *kobj, struct kobject *target,
+ const char *name)
+{
+ return sysfs_do_create_link(kobj, target, name, 0);
+}
+EXPORT_SYMBOL_GPL(sysfs_create_link_nowarn);
+
+/**
+ * sysfs_delete_link - remove symlink in object's directory.
+ * @kobj: object we're acting for.
+ * @targ: object we're pointing to.
+ * @name: name of the symlink to remove.
+ *
+ * Unlike sysfs_remove_link sysfs_delete_link has enough information
+ * to successfully delete symlinks in tagged directories.
+ */
+void sysfs_delete_link(struct kobject *kobj, struct kobject *targ,
+ const char *name)
+{
+ const void *ns = NULL;
+
+ /*
+ * We don't own @target and it may be removed at any time.
+ * Synchronize using sysfs_symlink_target_lock. See
+ * sysfs_remove_dir() for details.
+ */
+ spin_lock(&sysfs_symlink_target_lock);
+ if (targ->sd && kernfs_ns_enabled(kobj->sd))
+ ns = targ->sd->ns;
+ spin_unlock(&sysfs_symlink_target_lock);
+ kernfs_remove_by_name_ns(kobj->sd, name, ns);
+}
+
+/**
+ * sysfs_remove_link - remove symlink in object's directory.
+ * @kobj: object we're acting for.
+ * @name: name of the symlink to remove.
+ */
+void sysfs_remove_link(struct kobject *kobj, const char *name)
+{
+ struct kernfs_node *parent = NULL;
+
+ if (!kobj)
+ parent = sysfs_root_kn;
+ else
+ parent = kobj->sd;
+
+ kernfs_remove_by_name(parent, name);
+}
+EXPORT_SYMBOL_GPL(sysfs_remove_link);
+
+/**
+ * sysfs_rename_link_ns - rename symlink in object's directory.
+ * @kobj: object we're acting for.
+ * @targ: object we're pointing to.
+ * @old: previous name of the symlink.
+ * @new: new name of the symlink.
+ * @new_ns: new namespace of the symlink.
+ *
+ * A helper function for the common rename symlink idiom.
+ */
+int sysfs_rename_link_ns(struct kobject *kobj, struct kobject *targ,
+ const char *old, const char *new, const void *new_ns)
+{
+ struct kernfs_node *parent, *kn = NULL;
+ const void *old_ns = NULL;
+ int result;
+
+ if (!kobj)
+ parent = sysfs_root_kn;
+ else
+ parent = kobj->sd;
+
+ if (targ->sd)
+ old_ns = targ->sd->ns;
+
+ result = -ENOENT;
+ kn = kernfs_find_and_get_ns(parent, old, old_ns);
+ if (!kn)
+ goto out;
+
+ result = -EINVAL;
+ if (kernfs_type(kn) != KERNFS_LINK)
+ goto out;
+ if (kn->symlink.target_kn->priv != targ)
+ goto out;
+
+ result = kernfs_rename_ns(kn, parent, new, new_ns);
+
+out:
+ kernfs_put(kn);
+ return result;
+}
+EXPORT_SYMBOL_GPL(sysfs_rename_link_ns);