Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> writes:
> On Wed, 16 Sep 2015 12:58:04 -0700 bsegall@xxxxxxxxxx wrote:
>
>> 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.
>
> (cc Eric)
(cc Containers)
Interesting. Strictly speaking the current behavior is not wrong.
Searching for all threads with a given uid has nothing to do with pids
so the pid namespace not limiting them is natural.
In practice I don't think anyone cares either way (except people with
one color or another of security hat on) so this might be a change we
can actually make.
In general it is probably better not to share uids and gids between
containers.
Ben do you have a use case where this actually matters? Or was this a
case of "That looks wrong..."?
Eric
>> Signed-off-by: Ben Segall <bsegall@xxxxxxxxxx>
>> Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
>> Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
>> ---
>> block/ioprio.c | 6 ++++--
>> kernel/sys.c | 4 ++--
>> 2 files changed, 6 insertions(+), 4 deletions(-)
>>
>> 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 @@ 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)
>> diff --git a/kernel/sys.c b/kernel/sys.c
>> index fa2f2f6..6af9212 100644
>> --- a/kernel/sys.c
>> +++ b/kernel/sys.c
>> @@ -222,7 +222,7 @@ SYSCALL_DEFINE3(setpriority, int, which, int, who, int, niceval)
>> goto out_unlock; /* No processes for this user */
>> }
>> do_each_thread(g, p) {
>> - if (uid_eq(task_uid(p), uid))
>> + if (uid_eq(task_uid(p), uid) && task_pid_vnr(p))
>> error = set_one_prio(p, niceval, error);
>> } while_each_thread(g, p);
>> if (!uid_eq(uid, cred->uid))
>> @@ -290,7 +290,7 @@ SYSCALL_DEFINE2(getpriority, int, which, int, who)
>> goto out_unlock; /* No processes for this user */
>> }
>> do_each_thread(g, p) {
>> - if (uid_eq(task_uid(p), uid)) {
>> + if (uid_eq(task_uid(p), uid) && task_pid_vnr(p)) {
>> niceval = nice_to_rlimit(task_nice(p));
>> if (niceval > retval)
>> retval = niceval;
>> --
>> 2.6.0.rc0.131.gf624c3d
>>
>> --
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