cgroup: Add generic cgroup subsystem permission checks.
Rather than using explicit euid == 0 checks when trying to move
tasks into a cgroup via CFS, move permission checks into each
specific cgroup subsystem. If a subsystem does not specify a
'can_attach' handler, then we fall back to doing our checks the old way.
This way non-root processes can add arbitrary processes to
a cgroup if all the registered subsystems on that cgroup agree.
Also change explicit euid == 0 check to CAP_SYS_ADMIN
Signed-off-by: San Mehat <san@google.com>
diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 9c9b754..a1df487 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -1373,6 +1373,13 @@
{
struct cpuset *cs = cgroup_cs(cont);
+ if ((current != task) && (!capable(CAP_SYS_ADMIN))) {
+ const struct cred *cred = current_cred(), *tcred;
+
+ if (cred->euid != tcred->uid && cred->euid != tcred->suid)
+ return -EPERM;
+ }
+
if (cpumask_empty(cs->cpus_allowed) || nodes_empty(cs->mems_allowed))
return -ENOSPC;