[PATCH v4 1/9] sysfs: add sysfs_file_change_owner_by_name()
From: Christian Brauner <hidden>
Date: 2020-02-24 17:22:04
Also in:
lkml, netdev
Subsystem:
driver core, kobjects, debugfs and sysfs, filesystems (vfs and infrastructure), the rest · Maintainers:
Greg Kroah-Hartman, "Rafael J. Wysocki", Danilo Krummrich, Alexander Viro, Christian Brauner, Linus Torvalds
Add helpers to change the owner of a sysfs files.
This function will be used to correctly account for kobject ownership
changes, e.g. when moving network devices between network namespaces.
Signed-off-by: Christian Brauner <redacted>
---
/* v2 */
- Greg Kroah-Hartman [off-list ref]:
- Better naming for sysfs_file_change_owner() to reflect the fact that it
can be used to change the owner of the kobject itself by passing NULL as
argument.
- Christian Brauner [off-list ref]:
- Split sysfs_file_change_owner() into two helpers sysfs_change_owner() and
sysfs_change_owner_by_name(). The former changes the owner of the kobject
itself, the latter the owner of the kobject looked up via the name
argument.
/* v3 */
- Greg Kroah-Hartman [off-list ref]:
- Add explicit uid/gid parameters.
/* v4 */
- Greg Kroah-Hartman [off-list ref]:
- Remove the second helper which changes the ownership of the kobject itself
and do it in-place instead later on in the series. A separate helper is
not needed for that.
- Christian Brauner [off-list ref]:
- Add more documentation.
---
fs/sysfs/file.c | 47 +++++++++++++++++++++++++++++++++++++++++++
include/linux/sysfs.h | 10 +++++++++
2 files changed, 57 insertions(+)
diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index 130fc6fbcc03..4ca936ca3ba4 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c@@ -558,3 +558,50 @@ void sysfs_remove_bin_file(struct kobject *kobj, kernfs_remove_by_name(kobj->sd, attr->attr.name); } EXPORT_SYMBOL_GPL(sysfs_remove_bin_file); + +static int internal_change_owner(struct kernfs_node *kn, kuid_t kuid, + kgid_t kgid) +{ + struct iattr newattrs = { + .ia_valid = ATTR_UID | ATTR_GID, + .ia_uid = kuid, + .ia_gid = kgid, + }; + return kernfs_setattr(kn, &newattrs); +} + +/** + * sysfs_file_change_owner - change owner of a sysfs file. + * @kobj: object. + * @name: name of the file to change. + * @kuid: new owner's kuid + * @kgid: new owner's kgid + * + * This function looks up the sysfs entry @name under @kobj and changes the + * ownership to @kuid/@kgid. + * + * Returns 0 on success or error code on failure. + */ +int sysfs_file_change_owner(struct kobject *kobj, const char *name, kuid_t kuid, + kgid_t kgid) +{ + struct kernfs_node *kn; + int error; + + if (!name) + return -EINVAL; + + if (!kobj->state_in_sysfs) + return -EINVAL; + + kn = kernfs_find_and_get(kobj->sd, name); + if (!kn) + return -ENOENT; + + error = internal_change_owner(kn, kuid, kgid); + + kernfs_put(kn); + + return error; +} +EXPORT_SYMBOL_GPL(sysfs_file_change_owner);
diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h
index fa7ee503fb76..a7884024a911 100644
--- a/include/linux/sysfs.h
+++ b/include/linux/sysfs.h@@ -310,6 +310,9 @@ static inline void sysfs_enable_ns(struct kernfs_node *kn) return kernfs_enable_ns(kn); } +int sysfs_file_change_owner(struct kobject *kobj, const char *name, kuid_t kuid, + kgid_t kgid); + #else /* CONFIG_SYSFS */ static inline int sysfs_create_dir_ns(struct kobject *kobj, const void *ns)
@@ -522,6 +525,13 @@ static inline void sysfs_enable_ns(struct kernfs_node *kn) { } +static inline int sysfs_file_change_owner(struct kobject *kobj, + const char *name, kuid_t kuid, + kgid_t kgid) +{ + return 0; +} + #endif /* CONFIG_SYSFS */ static inline int __must_check sysfs_create_file(struct kobject *kobj,
--
2.25.1