3 files changed, 2 insertions, 73 deletions

diff --git a/include/linux/cgroup-defs.h b/include/linux/cgroup-defs.h
index d3036be98027..8a590cd40be0 100644
--- a/include/linux/cgroup-defs.h
+++ b/include/linux/cgroup-defs.h
@@ -452,8 +452,6 @@ struct cgroup_subsys {
 	void (*css_free)(struct cgroup_subsys_state *css);
 	void (*css_reset)(struct cgroup_subsys_state *css);
 
-	int (*allow_attach)(struct cgroup_subsys_state *css,
-			    struct cgroup_taskset *tset);
 	int (*can_attach)(struct cgroup_taskset *tset);
 	void (*cancel_attach)(struct cgroup_taskset *tset);
 	void (*attach)(struct cgroup_taskset *tset);
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index f3b356ee66d6..ca47b5d42764 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -640,17 +640,6 @@ static inline void cgroup_kthread_ready(void)
 	current->no_cgroup_migration = 0;
 }
 
-/*
- * Default Android check for whether the current process is allowed to move a
- * task across cgroups, either because CAP_SYS_NICE is set or because the uid
- * of the calling process is the same as the moved task or because we are
- * running as root.
- * Returns 0 if this is allowed, or -EACCES otherwise.
- */
-int subsys_cgroup_allow_attach(struct cgroup_subsys_state *css,
-			       struct cgroup_taskset *tset);
-
-
 #else /* !CONFIG_CGROUPS */
 
 struct cgroup_subsys_state;
@@ -681,11 +670,6 @@ static inline bool task_under_cgroup_hierarchy(struct task_struct *task,
 static inline void cgroup_init_kthreadd(void) {}
 static inline void cgroup_kthread_ready(void) {}
 
-static inline int subsys_cgroup_allow_attach(struct cgroup_subsys_state *css,
-					     struct cgroup_taskset *tset)
-{
-	return 0;
-}
 #endif /* !CONFIG_CGROUPS */
 
 /*
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index c2508ca442b7..64a3b3db2484 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -2848,44 +2848,6 @@ static int cgroup_attach_task(struct cgroup *dst_cgrp,
 	return ret;
 }
 
-int subsys_cgroup_allow_attach(struct cgroup_subsys_state *css, struct cgroup_taskset *tset)
-{
-	const struct cred *cred = current_cred(), *tcred;
-	struct task_struct *task;
-
-	if (capable(CAP_SYS_NICE))
-		return 0;
-
-	cgroup_taskset_for_each(task, css, tset) {
-		tcred = __task_cred(task);
-
-		if (current != task && !uid_eq(cred->euid, tcred->uid) &&
-		    !uid_eq(cred->euid, tcred->suid))
-			return -EACCES;
-	}
-
-	return 0;
-}
-
-static int cgroup_allow_attach(struct cgroup *cgrp, struct cgroup_taskset *tset)
-{
-	struct cgroup_subsys_state *css;
-	int i;
-	int ret;
-
-	for_each_css(css, i, cgrp) {
-		if (css->ss->allow_attach) {
-			ret = css->ss->allow_attach(css, tset);
-			if (ret)
-				return ret;
-		} else {
-			return -EACCES;
-		}
-	}
-
-	return 0;
-}
-
 static int cgroup_procs_write_permission(struct task_struct *task,
 					 struct cgroup *dst_cgrp,
 					 struct kernfs_open_file *of)
@@ -2901,23 +2863,8 @@ static int cgroup_procs_write_permission(struct task_struct *task,
 	if (!uid_eq(cred->euid, GLOBAL_ROOT_UID) &&
 	    !uid_eq(cred->euid, tcred->uid) &&
 	    !uid_eq(cred->euid, tcred->suid) &&
-	    !ns_capable(tcred->user_ns, CAP_SYS_NICE)) {
-		/*
-		 * if the default permission check fails, give each
-		 * cgroup a chance to extend the permission check
-		 */
-		struct cgroup_taskset tset = {
-			.src_csets = LIST_HEAD_INIT(tset.src_csets),
-			.dst_csets = LIST_HEAD_INIT(tset.dst_csets),
-			.csets = &tset.src_csets,
-		};
-		struct css_set *cset;
-		cset = task_css_set(task);
-		list_add(&cset->mg_node, &tset.src_csets);
-		ret = cgroup_allow_attach(dst_cgrp, &tset);
-		if (ret)
-			ret = -EACCES;
-	}
+	    !ns_capable(tcred->user_ns, CAP_SYS_NICE))
+		ret = -EACCES;
 
 	if (!ret && cgroup_on_dfl(dst_cgrp)) {
 		struct super_block *sb = of->file->f_path.dentry->d_sb;