pidns: fix set/getpriority and ioprio_set/get in PRIO_USER mode
setpriority(PRIO_USER, 0, x) will change the priority of tasks outside of
the current pid namespace. This is in contrast to both the other modes of
setpriority and the example of kill(-1). Fix this. getpriority and
ioprio have the same failure mode, fix them too.
Eric said:
: After some more thinking about it this patch sounds justifiable.
:
: My goal with namespaces is not to build perfect isolation mechanisms
: as that can get into ill defined territory, but to build well defined
: mechanisms. And to handle the corner cases so you can use only
: a single namespace with well defined results.
:
: In this case you have found the two interfaces I am aware of that
: identify processes by uid instead of by pid. Which quite frankly is
: weird. Unfortunately the weird unexpected cases are hard to handle
: in the usual way.
:
: I was hoping for a little more information. Changes like this one we
: have to be careful of because someone might be depending on the current
: behavior. I don't think they are and I do think this make sense as part
: of the pid namespace.
Signed-off-by: Ben Segall <bsegall@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Ambrose Feinstein <ambrose@google.com>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/block/ioprio.c b/block/ioprio.c
index 31666c9..cc7800e 100644
--- a/block/ioprio.c
+++ b/block/ioprio.c
@@ -123,7 +123,8 @@
break;
do_each_thread(g, p) {
- if (!uid_eq(task_uid(p), uid))
+ if (!uid_eq(task_uid(p), uid) ||
+ !task_pid_vnr(p))
continue;
ret = set_task_ioprio(p, ioprio);
if (ret)
@@ -220,7 +221,8 @@
break;
do_each_thread(g, p) {
- if (!uid_eq(task_uid(p), user->uid))
+ if (!uid_eq(task_uid(p), user->uid) ||
+ !task_pid_vnr(p))
continue;
tmpio = get_task_ioprio(p);
if (tmpio < 0)
