Re: [PATCH v2 2/3] x86/speculation: Apply IBPB more strictly to avoid cross-process spectre v2 leak

2018-09-03 Thread Jiri Kosina
On Mon, 3 Sep 2018, Peter Zijlstra wrote: > > if (tsk && tsk->mm && > > tsk->mm->context.ctx_id != last_ctx_id && > > - get_dumpable(tsk->mm) != SUID_DUMP_USER) > > + ___ptrace_may_access(tsk, current, PTRACE_MODE_IBPB)) > >

Re: [PATCH v2 2/3] x86/speculation: Apply IBPB more strictly to avoid cross-process spectre v2 leak

2018-09-03 Thread Jiri Kosina
On Mon, 3 Sep 2018, Peter Zijlstra wrote: > > if (tsk && tsk->mm && > > tsk->mm->context.ctx_id != last_ctx_id && > > - get_dumpable(tsk->mm) != SUID_DUMP_USER) > > + ___ptrace_may_access(tsk, current, PTRACE_MODE_IBPB)) > >

Re: [PATCH v2 2/3] x86/speculation: Apply IBPB more strictly to avoid cross-process spectre v2 leak

2018-09-03 Thread Peter Zijlstra
On Mon, Sep 03, 2018 at 02:45:25PM +0200, Jiri Kosina wrote: > if (tsk && tsk->mm && > tsk->mm->context.ctx_id != last_ctx_id && > - get_dumpable(tsk->mm) != SUID_DUMP_USER) > + ___ptrace_may_access(tsk, current, PTRACE_MODE_IBPB)) >

Re: [PATCH v2 2/3] x86/speculation: Apply IBPB more strictly to avoid cross-process spectre v2 leak

2018-09-03 Thread Peter Zijlstra
On Mon, Sep 03, 2018 at 02:45:25PM +0200, Jiri Kosina wrote: > if (tsk && tsk->mm && > tsk->mm->context.ctx_id != last_ctx_id && > - get_dumpable(tsk->mm) != SUID_DUMP_USER) > + ___ptrace_may_access(tsk, current, PTRACE_MODE_IBPB)) >

[PATCH v2 2/3] x86/speculation: Apply IBPB more strictly to avoid cross-process spectre v2 leak

2018-09-03 Thread Jiri Kosina
From: Jiri Kosina Currently, we are issuing IBPB only in cases when switching into a non-dumpable process, the rationale being to protect such 'important and security sensitive' processess (such as GPG) from data leak into a different userspace process via spectre v2. This is however completely

[PATCH v2 2/3] x86/speculation: Apply IBPB more strictly to avoid cross-process spectre v2 leak

2018-09-03 Thread Jiri Kosina
From: Jiri Kosina Currently, we are issuing IBPB only in cases when switching into a non-dumpable process, the rationale being to protect such 'important and security sensitive' processess (such as GPG) from data leak into a different userspace process via spectre v2. This is however completely