lkml.org 
[lkml]   [2018]   [Mar]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] mm: relax ptrace mode in process_vm_readv(2)
On Mon, Mar 05, 2018 at 04:07:10PM -0800, Andrew Morton wrote:
> On Sat, 3 Mar 2018 23:11:16 +0300 Alexey Dobriyan <adobriyan@gmail.com> wrote:
>
> > It is more natural to check for read-from-memory permissions in case of
> > process_vm_readv() as PTRACE_MODE_ATTACH is equivalent to write
> > permissions.
> >
> > ...
> >
> > --- a/mm/process_vm_access.c
> > +++ b/mm/process_vm_access.c
> > @@ -204,7 +204,7 @@ static ssize_t process_vm_rw_core(pid_t pid, struct iov_iter *iter,
> > goto free_proc_pages;
> > }
> >
> > - mm = mm_access(task, PTRACE_MODE_ATTACH_REALCREDS);
> > + mm = mm_access(task, vm_write ? PTRACE_MODE_ATTACH_REALCREDS : PTRACE_MODE_READ_REALCREDS);
> > if (!mm || IS_ERR(mm)) {
> > rc = IS_ERR(mm) ? PTR_ERR(mm) : -ESRCH;
> > /*
>
> But what is the risk of breaking existing userspace?

Permissions for write/ATTACH should be more strict than for read/READ,
so loosening them should be fine.

Unless LSM does silly things of course.

\
 
 \ /
  Last update: 2018-03-06 18:45    [W:0.382 / U:0.656 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site