freebsd-skq/sys/amd64/include/pcb.h
kib b4c82b3b07 PTI: Trap if we returned to userspace with kernel (full) page table
still active.

Map userspace portion of VA in the PTI kernel-mode page table as
non-executable. This way, if we ever miss reloading ucr3 into %cr3 on
the return to usermode, the process traps instead of executing in
potentially vulnerable setup.  Catch the condition of such trap and
verify user-mode %cr3, which is saved by page fault handler.

I peek this trick in some article about Linux implementation.

Reviewed by:	alc, markj (previous version)
Sponsored by:	The FreeBSD Foundation
MFC after:	12 days
DIfferential revision:	https://reviews.freebsd.org/D13956
2018-01-19 22:10:29 +00:00

136 lines
4.1 KiB
C

/*-
* SPDX-License-Identifier: BSD-3-Clause
*
* Copyright (c) 2003 Peter Wemm.
* Copyright (c) 1990 The Regents of the University of California.
* All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* William Jolitz.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* from: @(#)pcb.h 5.10 (Berkeley) 5/12/91
* $FreeBSD$
*/
#ifndef _AMD64_PCB_H_
#define _AMD64_PCB_H_
/*
* AMD64 process control block
*/
#include <machine/fpu.h>
#include <machine/segments.h>
#ifdef __amd64__
/*
* NB: The fields marked with (*) are used by kernel debuggers. Their
* ABI should be preserved.
*/
struct pcb {
register_t pcb_r15; /* (*) */
register_t pcb_r14; /* (*) */
register_t pcb_r13; /* (*) */
register_t pcb_r12; /* (*) */
register_t pcb_rbp; /* (*) */
register_t pcb_rsp; /* (*) */
register_t pcb_rbx; /* (*) */
register_t pcb_rip; /* (*) */
register_t pcb_fsbase;
register_t pcb_gsbase;
register_t pcb_kgsbase;
register_t pcb_cr0;
register_t pcb_cr2;
register_t pcb_cr3;
register_t pcb_cr4;
register_t pcb_dr0;
register_t pcb_dr1;
register_t pcb_dr2;
register_t pcb_dr3;
register_t pcb_dr6;
register_t pcb_dr7;
struct region_descriptor pcb_gdt;
struct region_descriptor pcb_idt;
struct region_descriptor pcb_ldt;
uint16_t pcb_tr;
u_int pcb_flags;
#define PCB_FULL_IRET 0x01 /* full iret is required */
#define PCB_DBREGS 0x02 /* process using debug registers */
#define PCB_KERNFPU 0x04 /* kernel uses fpu */
#define PCB_FPUINITDONE 0x08 /* fpu state is initialized */
#define PCB_USERFPUINITDONE 0x10 /* fpu user state is initialized */
#define PCB_32BIT 0x40 /* process has 32 bit context (segs etc) */
#define PCB_FPUNOSAVE 0x80 /* no save area for current FPU ctx */
uint16_t pcb_initial_fpucw;
/* copyin/out fault recovery */
caddr_t pcb_onfault;
uint64_t pcb_saved_ucr3;
/* local tss, with i/o bitmap; NULL for common */
struct amd64tss *pcb_tssp;
/* model specific registers */
register_t pcb_efer;
register_t pcb_star;
register_t pcb_lstar;
register_t pcb_cstar;
register_t pcb_sfmask;
struct savefpu *pcb_save;
uint64_t pcb_pad[5];
};
/* Per-CPU state saved during suspend and resume. */
struct susppcb {
struct pcb sp_pcb;
/* fpu context for suspend/resume */
void *sp_fpususpend;
};
#endif
#ifdef _KERNEL
struct trapframe;
void clear_pcb_flags(struct pcb *pcb, const u_int flags);
void makectx(struct trapframe *, struct pcb *);
void set_pcb_flags(struct pcb *pcb, const u_int flags);
void set_pcb_flags_raw(struct pcb *pcb, const u_int flags);
int savectx(struct pcb *) __returns_twice;
void resumectx(struct pcb *);
/* Ensure that pcb_gsbase and pcb_fsbase are up to date */
#define update_pcb_bases(pcb) set_pcb_flags((pcb), PCB_FULL_IRET)
#endif
#endif /* _AMD64_PCB_H_ */