From 8639b46139b0e4ea3b1ab1c274e410ee327f1d89 Mon Sep 17 00:00:00 2001 From: Ben Segall Date: Fri, 6 Nov 2015 16:32:48 -0800 Subject: 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 Cc: Oleg Nesterov Cc: Al Viro Cc: Ambrose Feinstein Acked-by: "Eric W. Biederman" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- block/ioprio.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) (limited to 'block') diff --git a/block/ioprio.c b/block/ioprio.c index 31666c92b46a..cc7800e9eb44 100644 --- a/block/ioprio.c +++ b/block/ioprio.c @@ -123,7 +123,8 @@ SYSCALL_DEFINE3(ioprio_set, int, which, int, who, int, ioprio) 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 @@ SYSCALL_DEFINE2(ioprio_get, int, which, int, who) 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) -- cgit v1.2.3