* [PATCH] mm: relax ptrace mode in process_vm_readv(2)
@ 2018-03-03 20:11 Alexey Dobriyan
2018-03-06 0:07 ` Andrew Morton
0 siblings, 1 reply; 3+ messages in thread
From: Alexey Dobriyan @ 2018-03-03 20:11 UTC (permalink / raw)
To: akpm; +Cc: linux-kernel, yeohc, jann
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.
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
---
mm/process_vm_access.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- 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;
/*
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH] mm: relax ptrace mode in process_vm_readv(2)
2018-03-03 20:11 [PATCH] mm: relax ptrace mode in process_vm_readv(2) Alexey Dobriyan
@ 2018-03-06 0:07 ` Andrew Morton
2018-03-06 17:44 ` Alexey Dobriyan
0 siblings, 1 reply; 3+ messages in thread
From: Andrew Morton @ 2018-03-06 0:07 UTC (permalink / raw)
To: Alexey Dobriyan; +Cc: linux-kernel, yeohc, jann
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?
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH] mm: relax ptrace mode in process_vm_readv(2)
2018-03-06 0:07 ` Andrew Morton
@ 2018-03-06 17:44 ` Alexey Dobriyan
0 siblings, 0 replies; 3+ messages in thread
From: Alexey Dobriyan @ 2018-03-06 17:44 UTC (permalink / raw)
To: Andrew Morton; +Cc: linux-kernel, yeohc, jann
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.
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2018-03-06 17:44 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz follow: Atom feed
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2018-03-03 20:11 [PATCH] mm: relax ptrace mode in process_vm_readv(2) Alexey Dobriyan
2018-03-06 0:07 ` Andrew Morton
2018-03-06 17:44 ` Alexey Dobriyan
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