/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 1993, David Greenman
 * All rights reserved.
 *
 * 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 AUTHOR 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 AUTHOR 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/param.h>
#include <sys/exec.h>
#include <sys/imgact.h>
#include <sys/imgact_aout.h>
#include <sys/kernel.h>
#include <sys/limits.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/racct.h>
#include <sys/resourcevar.h>
#include <sys/signalvar.h>
#include <sys/syscall.h>
#include <sys/sysent.h>
#include <sys/systm.h>
#include <sys/vnode.h>

#include <machine/frame.h>
#include <machine/md_var.h>

#include <vm/vm.h>
#include <vm/pmap.h>
#include <vm/vm_map.h>
#include <vm/vm_object.h>
#include <vm/vm_param.h>

#ifdef __amd64__
#include <compat/freebsd32/freebsd32_signal.h>
#include <compat/freebsd32/freebsd32_util.h>
#include <compat/freebsd32/freebsd32_proto.h>
#include <compat/freebsd32/freebsd32_syscall.h>
#include <compat/ia32/ia32_signal.h>
#endif

static int      exec_aout_imgact(struct image_params *imgp);
static int      aout_fixup(uintptr_t *stack_base, struct image_params *imgp);

#define AOUT32_USRSTACK         0xbfc00000

#if defined(__i386__)

#define AOUT32_PS_STRINGS       (AOUT32_USRSTACK - sizeof(struct ps_strings))

struct sysentvec aout_sysvec = {
        .sv_size        = SYS_MAXSYSCALL,
        .sv_table       = sysent,
        .sv_fixup       = aout_fixup,
        .sv_sendsig     = sendsig,
        .sv_sigcode     = sigcode,
        .sv_szsigcode   = &szsigcode,
        .sv_name        = "FreeBSD a.out",
        .sv_coredump    = NULL,
        .sv_minsigstksz = MINSIGSTKSZ,
        .sv_minuser     = VM_MIN_ADDRESS,
        .sv_maxuser     = AOUT32_USRSTACK,
        .sv_usrstack    = AOUT32_USRSTACK,
        .sv_psstrings   = AOUT32_PS_STRINGS,
        .sv_psstringssz = sizeof(struct ps_strings),
        .sv_stackprot   = VM_PROT_ALL,
        .sv_copyout_strings     = exec_copyout_strings,
        .sv_setregs     = exec_setregs,
        .sv_fixlimit    = NULL,
        .sv_maxssiz     = NULL,
        .sv_flags       = SV_ABI_FREEBSD | SV_AOUT | SV_ILP32 | SV_SIGSYS,
        .sv_set_syscall_retval = cpu_set_syscall_retval,
        .sv_fetch_syscall_args = cpu_fetch_syscall_args,
        .sv_syscallnames = syscallnames,
        .sv_schedtail   = NULL,
        .sv_thread_detach = NULL,
        .sv_trap        = NULL,
        .sv_onexec_old = exec_onexec_old,
        .sv_onexit =  exit_onexit,
        .sv_set_fork_retval = x86_set_fork_retval,
};

#elif defined(__amd64__)

#include "vdso_ia32_offsets.h"

extern const char _binary_elf_vdso32_so_1_start[];
extern const char _binary_elf_vdso32_so_1_end[];
extern char _binary_elf_vdso32_so_1_size;

#define AOUT32_PS_STRINGS \
    (AOUT32_USRSTACK - sizeof(struct freebsd32_ps_strings))
#define AOUT32_MINUSER          FREEBSD32_MINUSER

extern const char *freebsd32_syscallnames[];
extern u_long ia32_maxssiz;

static int aout_szsigcode;

struct sysentvec aout_sysvec = {
        .sv_size        = FREEBSD32_SYS_MAXSYSCALL,
        .sv_table       = freebsd32_sysent,
        .sv_fixup       = aout_fixup,
        .sv_sendsig     = ia32_sendsig,
        .sv_sigcode     = _binary_elf_vdso32_so_1_start,
        .sv_szsigcode   = &aout_szsigcode,
        .sv_name        = "FreeBSD a.out",
        .sv_coredump    = NULL,
        .sv_minsigstksz = MINSIGSTKSZ,
        .sv_minuser     = AOUT32_MINUSER,
        .sv_maxuser     = AOUT32_USRSTACK,
        .sv_usrstack    = AOUT32_USRSTACK,
        .sv_psstrings   = AOUT32_PS_STRINGS,
        .sv_psstringssz = sizeof(struct freebsd32_ps_strings),
        .sv_stackprot   = VM_PROT_ALL,
        .sv_copyout_strings     = freebsd32_copyout_strings,
        .sv_setregs     = ia32_setregs,
        .sv_fixlimit    = ia32_fixlimit,
        .sv_maxssiz     = &ia32_maxssiz,
        .sv_flags       = SV_ABI_FREEBSD | SV_AOUT | SV_ILP32 | SV_SIGSYS,
        .sv_set_syscall_retval = ia32_set_syscall_retval,
        .sv_fetch_syscall_args = ia32_fetch_syscall_args,
        .sv_syscallnames = freebsd32_syscallnames,
        .sv_onexec_old  = exec_onexec_old,
        .sv_onexit      = exit_onexit,
        .sv_set_fork_retval = x86_set_fork_retval,
};

static void
aout_sysent(void *arg __unused)
{
        aout_szsigcode = (int)(uintptr_t)&_binary_elf_vdso32_so_1_size;
}
SYSINIT(aout_sysent, SI_SUB_EXEC, SI_ORDER_ANY, aout_sysent, NULL);
#else
#error "Only ia32 arch is supported"
#endif

static int
aout_fixup(uintptr_t *stack_base, struct image_params *imgp)
{

        *stack_base -= sizeof(uint32_t);
        if (suword32((void *)*stack_base, imgp->args->argc) != 0)
                return (EFAULT);
        return (0);
}

static int
exec_aout_imgact(struct image_params *imgp)
{
        const struct exec *a_out;
        struct vmspace *vmspace;
        vm_map_t map;
        vm_object_t object;
        vm_offset_t text_end, data_end;
        unsigned long virtual_offset;
        unsigned long file_offset;
        unsigned long bss_size;
        int error;

        a_out = (const struct exec *)imgp->image_header;

        /*
         * Linux and *BSD binaries look very much alike,
         * only the machine id is different:
         * 0x64 for Linux, 0x86 for *BSD, 0x00 for BSDI.
         * NetBSD is in network byte order.. ugh.
         */
        if (((a_out->a_midmag >> 16) & 0xff) != 0x86 &&
            ((a_out->a_midmag >> 16) & 0xff) != 0 &&
            ((((int)ntohl(a_out->a_midmag)) >> 16) & 0xff) != 0x86)
                return (-1);

        /*
         * Set file/virtual offset based on a.out variant.
         *      We do two cases: host byte order and network byte order
         *      (for NetBSD compatibility)
         */
        switch ((int)(a_out->a_midmag & 0xffff)) {
        case ZMAGIC:
                virtual_offset = 0;
                if (a_out->a_text) {
                        file_offset = PAGE_SIZE;
                } else {
                        /* Bill's "screwball mode" */
                        file_offset = 0;
                }
                break;
        case QMAGIC:
                virtual_offset = PAGE_SIZE;
                file_offset = 0;
                /* Pass PS_STRINGS for BSD/OS binaries only. */
                if (N_GETMID(*a_out) == MID_ZERO)
                        imgp->ps_strings = (void *)aout_sysvec.sv_psstrings;
                break;
        default:
                /* NetBSD compatibility */
                switch ((int)(ntohl(a_out->a_midmag) & 0xffff)) {
                case ZMAGIC:
                case QMAGIC:
                        virtual_offset = PAGE_SIZE;
                        file_offset = 0;
                        break;
                default:
                        return (-1);
                }
        }

        bss_size = roundup(a_out->a_bss, PAGE_SIZE);

        /*
         * Check various fields in header for validity/bounds.
         */
        if (/* entry point must lay with text region */
            a_out->a_entry < virtual_offset ||
            a_out->a_entry >= virtual_offset + a_out->a_text ||

            /* text and data size must each be page rounded */
            a_out->a_text & PAGE_MASK || a_out->a_data & PAGE_MASK

#ifdef __amd64__
            ||
            /* overflows */
            virtual_offset + a_out->a_text + a_out->a_data + bss_size > UINT_MAX
#endif
            )
                return (-1);

        /* text + data can't exceed file size */
        if (a_out->a_data + a_out->a_text > imgp->attr->va_size)
                return (EFAULT);

        /*
         * text/data/bss must not exceed limits
         */
        PROC_LOCK(imgp->proc);
        if (/* text can't exceed maximum text size */
            a_out->a_text > maxtsiz ||

            /* data + bss can't exceed rlimit */
            a_out->a_data + bss_size > lim_cur_proc(imgp->proc, RLIMIT_DATA) ||
            racct_set(imgp->proc, RACCT_DATA, a_out->a_data + bss_size) != 0) {
                PROC_UNLOCK(imgp->proc);
                return (ENOMEM);
        }
        PROC_UNLOCK(imgp->proc);

        /*
         * Avoid a possible deadlock if the current address space is destroyed
         * and that address space maps the locked vnode.  In the common case,
         * the locked vnode's v_usecount is decremented but remains greater
         * than zero.  Consequently, the vnode lock is not needed by vrele().
         * However, in cases where the vnode lock is external, such as nullfs,
         * v_usecount may become zero.
         */
        VOP_UNLOCK(imgp->vp);

        /*
         * Destroy old process VM and create a new one (with a new stack)
         */
        error = exec_new_vmspace(imgp, &aout_sysvec);

        vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
        if (error)
                return (error);

        /*
         * The vm space can be changed by exec_new_vmspace
         */
        vmspace = imgp->proc->p_vmspace;

        object = imgp->object;
        map = &vmspace->vm_map;
        vm_map_lock(map);
        vm_object_reference(object);

        text_end = virtual_offset + a_out->a_text;
        error = vm_map_insert(map, object,
                file_offset,
                virtual_offset, text_end,
                VM_PROT_READ | VM_PROT_EXECUTE, VM_PROT_ALL,
                MAP_COPY_ON_WRITE | MAP_PREFAULT | MAP_VN_EXEC);
        if (error) {
                vm_map_unlock(map);
                vm_object_deallocate(object);
                return (error);
        }
        VOP_SET_TEXT_CHECKED(imgp->vp);
        data_end = text_end + a_out->a_data;
        if (a_out->a_data) {
                vm_object_reference(object);
                error = vm_map_insert(map, object,
                        file_offset + a_out->a_text,
                        text_end, data_end,
                        VM_PROT_ALL, VM_PROT_ALL,
                        MAP_COPY_ON_WRITE | MAP_PREFAULT | MAP_VN_EXEC);
                if (error) {
                        vm_map_unlock(map);
                        vm_object_deallocate(object);
                        return (error);
                }
                VOP_SET_TEXT_CHECKED(imgp->vp);
        }

        if (bss_size) {
                error = vm_map_insert(map, NULL, 0,
                        data_end, data_end + bss_size,
                        VM_PROT_ALL, VM_PROT_ALL, 0);
                if (error) {
                        vm_map_unlock(map);
                        return (error);
                }
        }
        vm_map_unlock(map);

        /* Fill in process VM information */
        vmspace->vm_tsize = a_out->a_text >> PAGE_SHIFT;
        vmspace->vm_dsize = (a_out->a_data + bss_size) >> PAGE_SHIFT;
        vmspace->vm_taddr = (caddr_t) (uintptr_t) virtual_offset;
        vmspace->vm_daddr = (caddr_t) (uintptr_t)
                            (virtual_offset + a_out->a_text);

        error = exec_map_stack(imgp);
        if (error != 0)
                return (error);

        /* Fill in image_params */
        imgp->interpreted = 0;
        imgp->entry_addr = a_out->a_entry;

        imgp->proc->p_sysent = &aout_sysvec;

        return (0);
}

/*
 * Tell kern_execve.c about it, with a little help from the linker.
 */
static struct execsw aout_execsw = {
        .ex_imgact = exec_aout_imgact,
        .ex_name = "a.out"
};
EXEC_SET(aout, aout_execsw);