Re: [PATCH] sys_capget should use current if the pid argument is 0

Chris Wright
2002-11-20T00:51:04Z

* Daniel Jacobowitz (dan@debian.org) wrote:
> On Fri, Oct 11, 2002 at 07:58:46PM -0700, Linus Torvalds wrote:
> >
> > On Thu, 10 Oct 2002, Chris Wright wrote:
> > >
> > > The patch below fixes my oversight. The locking is left the way it was,
> > > and just the pid 0 part is fixed as well as the duplicate code removed.
> >
> > All right, call me stupid, but twhere is the "duplication" in the code you
> > removed?
> >
> > I see the "security/capability.c" thing, yes, but I also look at
> > "security/dummy.c", and it appears that at least for that case nobody
> > would ever initialize the capabilities that we return to user space at
> > all.
> >
> > So there's a bug somewhere there, and removing the duplication makes
> > things worse (admittedly for a case which isn't enabled in the regular
> > kernel, but still..)
> >
> > So I'd ask you to have patience with me, and send a third patch that gets
> > this thing right too..
>
> Since this is still broken a month later... I don't know what to do
> about the "duplication" question, but I'll leave that to Chris. This
> is the uncontroversial portion of Chris's patch; its affect is to
> change my zsh shell prompt back to a '%' as I'd expect.

Thanks Daniel. I've been using the patch below, which differs only
slightly from the one you posted (code style matches the same lookup in
sys_capset). I'll follow up with the patch that removes the duplicate
code.

[PATCH] sys_capget should use current if the pid argument is 0

===== kernel/capability.c 1.5 vs edited =====
--- 1.5/kernel/capability.c Sun Sep 15 12:19:29 2002
+++ edited/kernel/capability.c Tue Nov 19 15:57:15 2002
@@ -54,11 +54,14 @@
spin_lock(&task_capability_lock);
read_lock(&tasklist_lock);

- target = find_task_by_pid(pid);
- if (!target) {
- ret = -ESRCH;
- goto out;
- }
+ if (pid && pid != current->pid) {
+ target = find_task_by_pid(pid);
+ if (!target) {
+ ret = -ESRCH;
+ goto out;
+ }
+ } else
+ target = current;

data.permitted = cap_t(target->cap_permitted);
data.inheritable = cap_t(target->cap_inheritable);