X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=kernel%2Fcgroup.c;h=b6a443e156b8ec545a7a16e113c4ae4964aa1281;hb=ed547bb16f27448033d0005c6ee3e282375a8f27;hp=470f6536b9e8cfb029eedb5ecdb3c3e8c3c341be;hpb=24bc3ea5df2e1d89e9d50ecca57c210b87ad61d2;p=firefly-linux-kernel-4.4.55.git

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 470f6536b9e8..b6a443e156b8 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -57,7 +57,7 @@
 #include <linux/vmalloc.h> /* TODO: replace with more sophisticated array */
 #include <linux/kthread.h>
 #include <linux/delay.h>
-
+#include <linux/cpuset.h>
 #include <linux/atomic.h>
 
 /*
@@ -2663,6 +2663,45 @@ static int cgroup_attach_task(struct cgroup *dst_cgrp,
 	return ret;
 }
 
+int subsys_cgroup_allow_attach(struct cgroup_taskset *tset)
+{
+	const struct cred *cred = current_cred(), *tcred;
+	struct task_struct *task;
+	struct cgroup_subsys_state *css;
+
+	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(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)
@@ -2677,8 +2716,24 @@ 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))
-		ret = -EACCES;
+	    !uid_eq(cred->euid, tcred->suid)) {
+		/*
+		 * 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);
+		list_del(&tset.src_csets);
+		if (ret)
+			ret = -EACCES;
+	}
 
 	if (!ret && cgroup_on_dfl(dst_cgrp)) {
 		struct super_block *sb = of->file->f_path.dentry->d_sb;
@@ -2764,6 +2819,7 @@ out_unlock_rcu:
 out_unlock_threadgroup:
 	percpu_up_write(&cgroup_threadgroup_rwsem);
 	cgroup_kn_unlock(of->kn);
+	cpuset_post_attach_flush();
 	return ret ?: nbytes;
 }
 
@@ -4783,6 +4839,7 @@ static void init_and_link_css(struct cgroup_subsys_state *css,
 	INIT_LIST_HEAD(&css->sibling);
 	INIT_LIST_HEAD(&css->children);
 	css->serial_nr = css_serial_nr_next++;
+	atomic_set(&css->online_cnt, 0);
 
 	if (cgroup_parent(cgrp)) {
 		css->parent = cgroup_css(cgroup_parent(cgrp), ss);
@@ -4805,6 +4862,10 @@ static int online_css(struct cgroup_subsys_state *css)
 	if (!ret) {
 		css->flags |= CSS_ONLINE;
 		rcu_assign_pointer(css->cgroup->subsys[ss->id], css);
+
+		atomic_inc(&css->online_cnt);
+		if (css->parent)
+			atomic_inc(&css->parent->online_cnt);
 	}
 	return ret;
 }
@@ -5036,10 +5097,15 @@ static void css_killed_work_fn(struct work_struct *work)
 		container_of(work, struct cgroup_subsys_state, destroy_work);
 
 	mutex_lock(&cgroup_mutex);
-	offline_css(css);
-	mutex_unlock(&cgroup_mutex);
 
-	css_put(css);
+	do {
+		offline_css(css);
+		css_put(css);
+		/* @css can't go away while we're holding cgroup_mutex */
+		css = css->parent;
+	} while (css && atomic_dec_and_test(&css->online_cnt));
+
+	mutex_unlock(&cgroup_mutex);
 }
 
 /* css kill confirmation processing requires process context, bounce */
@@ -5048,8 +5114,10 @@ static void css_killed_ref_fn(struct percpu_ref *ref)
 	struct cgroup_subsys_state *css =
 		container_of(ref, struct cgroup_subsys_state, refcnt);
 
-	INIT_WORK(&css->destroy_work, css_killed_work_fn);
-	queue_work(cgroup_destroy_wq, &css->destroy_work);
+	if (atomic_dec_and_test(&css->online_cnt)) {
+		INIT_WORK(&css->destroy_work, css_killed_work_fn);
+		queue_work(cgroup_destroy_wq, &css->destroy_work);
+	}
 }
 
 /**