Messages in this thread | | | From | (Eric W. Biederman) | Date | Mon, 21 Sep 2015 12:46:56 -0500 | Subject | Re: [PATCH] pidns: fix set/getpriority and ioprio_set/get in PRIO_USER mode |
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Andrew Morton <akpm@linux-foundation.org> writes:
> On Wed, 16 Sep 2015 12:58:04 -0700 bsegall@google.com 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@google.com> >> Cc: Oleg Nesterov <oleg@redhat.com> >> Cc: Al Viro <viro@zeniv.linux.org.uk> >> --- >> 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 >> >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in >> the body of a message to majordomo@vger.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html >> Please read the FAQ at http://www.tux.org/lkml/
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