On 08/01/2016 04:58 PM, Dave Hansen wrote:

On 08/01/2016 07:42 AM, Vlastimil Babka wrote:

quoted

On 07/29/2016 06:30 PM, Dave Hansen wrote:

quoted

This does not cause any practical problems with applications
using protection keys because we require them to specify initial
permissions for each key when it is allocated, which override the
restrictive default.

Here you mean the init_access_rights parameter of pkey_alloc()? So will
children of fork() after that pkey_alloc() inherit the new value or go
default?

Hi Vlastimil,

Yes, exactly, the initial permissions are provided via pkey_alloc()'s
'init_access_rights' argument.

OK. I was a bit sceptical of that part of the syscall, as you removed 
other syscalls changing PKRU for the thread in kernel, so leaving this 
seemed odd. But it makes sense to me together with the restrictive default.

Do you mean fork() or clone()?  In both cases, we actually copy the FPU
state from the parent, so children always inherit the state from their
parent which contains the permissions set by the parent's calls to
pkey_alloc().

I meant just fork() as I misunderstood the changelog in that clone() is 
different. Thanks for clarifying.

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