kernfs: implement "trusted.*" xattr support

kernfs inherited "security.*" xattr support from sysfs.  This patch
extends xattr support to "trusted.*" using simple_xattr_*().  As
trusted xattrs are restricted to CAP_SYS_ADMIN, simple_xattr_*() which
uses kernel memory for storage shouldn't be problematic.

Note that the existing "security.*" support doesn't implement
get/remove/list and the this patch only implements those ops for
"trusted.*".  We probably want to extend those ops to include support
for "security.*".

This patch will allow using kernfs from cgroup which requires
"trusted.*" xattr support.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: David P. Quigley <dpquigl@tycho.nsa.gov>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 9 insertions, 3 deletions

diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index f51e0625e666..a441e3be8052 100644
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -243,9 +243,12 @@ void kernfs_put(struct sysfs_dirent *sd)
                 kernfs_put(sd->s_symlink.target_sd);
         if (sysfs_type(sd) & SYSFS_COPY_NAME)
                 kfree(sd->s_name);
-        if (sd->s_iattr && sd->s_iattr->ia_secdata)
-                security_release_secctx(sd->s_iattr->ia_secdata,
-                                        sd->s_iattr->ia_secdata_len);
+        if (sd->s_iattr) {
+                if (sd->s_iattr->ia_secdata)
+                        security_release_secctx(sd->s_iattr->ia_secdata,
+                                                sd->s_iattr->ia_secdata_len);
+                simple_xattrs_free(&sd->s_iattr->xattrs);
+        }
         kfree(sd->s_iattr);
         ida_simple_remove(&root->ino_ida, sd->s_ino);
         kmem_cache_free(sysfs_dir_cachep, sd);
@@ -718,6 +721,9 @@ const struct inode_operations sysfs_dir_inode_operations = {
         .setattr        = sysfs_setattr,
         .getattr        = sysfs_getattr,
         .setxattr       = sysfs_setxattr,
+        .removexattr    = sysfs_removexattr,
+        .getxattr       = sysfs_getxattr,
+        .listxattr      = sysfs_listxattr,
 };
 
 static struct sysfs_dirent *sysfs_leftmost_descendant(struct sysfs_dirent *pos)