Return to exec_machdep.c CVS log

Up to [cvs.NetBSD.org] / src / sys / arch / aarch64 / aarch64

Not only the kernel thread, but also the userland PAC keys
(APIA,APIB,APDA,APDB,APGA) are now randomly initialized at exec, and switched
when context switch.
userland programs are able to perform pointer authentication on ARMv8.3+PAC cpu.

reviewd by maxv@, thanks.

/* $NetBSD: exec_machdep.c,v 1.7 2020/05/23 18:08:59 ryo Exp $ */

/*-
 * Copyright (c) 2014 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Matt Thomas of 3am Software Foundry.
 *
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
 */

#include <sys/cdefs.h>

__KERNEL_RCSID(1, "$NetBSD: exec_machdep.c,v 1.7 2020/05/23 18:08:59 ryo Exp $");

#include "opt_compat_netbsd.h"
#include "opt_compat_netbsd32.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/exec.h>
#include <sys/cprng.h>

#include <uvm/uvm_extern.h>

#include <compat/common/compat_util.h>
#include <sys/exec_elf.h>			/* mandatory */

#ifdef COMPAT_NETBSD32
#include <compat/netbsd32/netbsd32_exec.h>
#endif

#include <aarch64/armreg.h>
#include <aarch64/cpufunc.h>
#include <aarch64/frame.h>
#include <aarch64/machdep.h>

#if EXEC_ELF64
int
aarch64_netbsd_elf64_probe(struct lwp *l, struct exec_package *epp, void *eh0,
	char *itp, vaddr_t *start_p)
{
	return 0;
}
#endif

#if EXEC_ELF32
int
aarch64_netbsd_elf32_probe(struct lwp *l, struct exec_package *epp, void *eh0,
	char *itp, vaddr_t *start_p)
{
	const Elf32_Ehdr * const eh = eh0;
	const bool elf_aapcs_p =
	    (eh->e_flags & EF_ARM_EABIMASK) >= EF_ARM_EABI_VER4;

	/* OABI not support */
	if (!elf_aapcs_p)
		return ENOEXEC;

	/*
	 * require aarch32 feature.
	 * XXX should consider some cluster may have no aarch32?
	 */
	if (__SHIFTOUT(l->l_cpu->ci_id.ac_aa64pfr0, ID_AA64PFR0_EL1_EL0) !=
	    ID_AA64PFR0_EL1_EL0_64_32)
		return ENOEXEC;

	/*
	 * Copy (if any) the machine_arch of the executable to the proc.
	 */
	CTASSERT(sizeof(l->l_proc->p_md.md_march32) ==
	    sizeof(epp->ep_machine_arch));
	if (epp->ep_machine_arch[0] != 0)
		strlcpy(l->l_proc->p_md.md_march32, epp->ep_machine_arch,
		    sizeof(l->l_proc->p_md.md_march32));

	return 0;
}
#endif

void
aarch64_setregs_ptrauth(struct lwp *l, bool randomize)
{
#ifdef ARMV83_PAC
	if (!aarch64_pac_enabled)
		return;

	if (randomize) {
		cprng_strong(kern_cprng, l->l_md.md_ia_user,
		    sizeof(l->l_md.md_ia_user), 0);
		cprng_strong(kern_cprng, l->l_md.md_ib_user,
		    sizeof(l->l_md.md_ib_user), 0);
		cprng_strong(kern_cprng, l->l_md.md_da_user,
		    sizeof(l->l_md.md_da_user), 0);
		cprng_strong(kern_cprng, l->l_md.md_db_user,
		    sizeof(l->l_md.md_db_user), 0);
		cprng_strong(kern_cprng, l->l_md.md_ga_user,
		    sizeof(l->l_md.md_ga_user), 0);
	} else {
		memset(l->l_md.md_ia_user, 0,
		    sizeof(l->l_md.md_ia_user));
		memset(l->l_md.md_ib_user, 0,
		    sizeof(l->l_md.md_ib_user));
		memset(l->l_md.md_da_user, 0,
		    sizeof(l->l_md.md_da_user));
		memset(l->l_md.md_db_user, 0,
		    sizeof(l->l_md.md_db_user));
		memset(l->l_md.md_ga_user, 0,
		    sizeof(l->l_md.md_ga_user));
	}
#endif
}

void
setregs(struct lwp *l, struct exec_package *pack, vaddr_t stack)
{
	struct proc * const p = l->l_proc;
	struct trapframe * const tf = l->l_md.md_utf;

	aarch64_setregs_ptrauth(l, true);

	p->p_flag &= ~PK_32;

	/*
	 * void __start(void (*cleanup)(void), const Obj_Entry *obj,
	 *    struct ps_strings *ps_strings);
	 */
	memset(tf, 0, sizeof(*tf));
	tf->tf_reg[2] = p->p_psstrp;
	tf->tf_pc = pack->ep_entry;
	tf->tf_sp = stack & -16L;
	tf->tf_spsr = SPSR_M_EL0T;
}