/*      $NetBSD: exec_subr.c,v 1.92 2026/05/11 02:05:31 thorpej Exp $   */

/*
 * Copyright (c) 1993, 1994, 1996 Christopher G. Demetriou
 * 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.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by Christopher G. Demetriou.
 * 4. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 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(0, "$NetBSD: exec_subr.c,v 1.92 2026/05/11 02:05:31 thorpej Exp $");

#include "opt_pax.h"

#include <sys/param.h>
#include <sys/types.h>

#include <sys/device.h>
#include <sys/exec.h>
#include <sys/filedesc.h>
#include <sys/kmem.h>
#include <sys/mman.h>
#include <sys/pax.h>
#include <sys/proc.h>
#include <sys/resourcevar.h>
#include <sys/sdt.h>
#include <sys/systm.h>
#include <sys/vnode.h>

#include <uvm/uvm_extern.h>

#define VMCMD_EVCNT_DECL(name)                                  \
static struct evcnt vmcmd_ev_##name =                           \
    EVCNT_INITIALIZER(EVCNT_TYPE_MISC, NULL, "vmcmd", #name);   \
EVCNT_ATTACH_STATIC(vmcmd_ev_##name)

#define VMCMD_EVCNT_INCR(name)                                  \
    vmcmd_ev_##name.ev_count++

VMCMD_EVCNT_DECL(calls);
VMCMD_EVCNT_DECL(extends);
VMCMD_EVCNT_DECL(kills);

#ifdef DEBUG_STACK
#define DPRINTF(a) uprintf a
#else
#define DPRINTF(a)
#endif

unsigned int user_stack_guard_size = 1024 * 1024;
unsigned int user_thread_stack_guard_size = 64 * 1024;

/*
 * new_vmcmd():
 *      create a new vmcmd structure and fill in its fields based
 *      on function call arguments.  make sure objects ref'd by
 *      the vmcmd are 'held'.
 */

void
new_vmcmd(struct exec_vmcmd_set *evsp,
    int (*proc)(struct lwp * l, struct exec_vmcmd *),
    vsize_t len, vaddr_t addr, struct vnode *vp, u_long offset,
    u_int prot, int flags)
{
        struct exec_vmcmd *vcp;

        VMCMD_EVCNT_INCR(calls);
        KASSERT(proc != vmcmd_map_pagedvn || (vp->v_iflag & VI_TEXT));
        KASSERT(vp == NULL || vrefcnt(vp) > 0);

        if (evsp->evs_used >= evsp->evs_cnt)
                vmcmdset_extend(evsp);
        vcp = &evsp->evs_cmds[evsp->evs_used++];
        vcp->ev_proc = proc;
        vcp->ev_len = len;
        vcp->ev_addr = addr;
        if ((vcp->ev_vp = vp) != NULL)
                vref(vp);
        vcp->ev_offset = offset;
        vcp->ev_prot = prot;
        vcp->ev_flags = flags;
}

void
vmcmdset_extend(struct exec_vmcmd_set *evsp)
{
        struct exec_vmcmd *nvcp;
        u_int ocnt;

#ifdef DIAGNOSTIC
        if (evsp->evs_used < evsp->evs_cnt)
                panic("vmcmdset_extend: not necessary");
#endif

        /* figure out number of entries in new set */
        if ((ocnt = evsp->evs_cnt) != 0) {
                evsp->evs_cnt += ocnt;
                VMCMD_EVCNT_INCR(extends);
        } else
                evsp->evs_cnt = EXEC_DEFAULT_VMCMD_SETSIZE;

        /* allocate it */
        nvcp = kmem_alloc(evsp->evs_cnt * sizeof(struct exec_vmcmd), KM_SLEEP);

        /* free the old struct, if there was one, and record the new one */
        if (ocnt) {
                memcpy(nvcp, evsp->evs_cmds,
                    (ocnt * sizeof(struct exec_vmcmd)));
                kmem_free(evsp->evs_cmds, ocnt * sizeof(struct exec_vmcmd));
        }
        evsp->evs_cmds = nvcp;
}

void
kill_vmcmds(struct exec_vmcmd_set *evsp)
{
        struct exec_vmcmd *vcp;
        u_int i;

        VMCMD_EVCNT_INCR(kills);

        if (evsp->evs_cnt == 0)
                return;

        for (i = 0; i < evsp->evs_used; i++) {
                vcp = &evsp->evs_cmds[i];
                if (vcp->ev_vp != NULL)
                        vrele(vcp->ev_vp);
        }
        kmem_free(evsp->evs_cmds, evsp->evs_cnt * sizeof(struct exec_vmcmd));
        evsp->evs_used = evsp->evs_cnt = 0;
}

/*
 * vmcmd_map_pagedvn():
 *      handle vmcmd which specifies that a vnode should be mmap'd.
 *      appropriate for handling demand-paged text and data segments.
 */

static int
vmcmd_get_prot(struct lwp *l, const struct exec_vmcmd *cmd, vm_prot_t *prot,
    vm_prot_t *maxprot)
{
        vm_prot_t extraprot = PROT_MPROTECT_EXTRACT(cmd->ev_prot);

        *prot = cmd->ev_prot & UVM_PROT_ALL;
        *maxprot = PAX_MPROTECT_MAXPROTECT(l, *prot, extraprot, UVM_PROT_ALL);

        if ((*prot & *maxprot) != *prot)
                return SET_ERROR(EACCES);
        return PAX_MPROTECT_VALIDATE(l, *prot);
}

int
vmcmd_map_pagedvn(struct lwp *l, struct exec_vmcmd *cmd)
{
        struct uvm_object *uobj;
        struct vnode *vp = cmd->ev_vp;
        struct proc *p = l->l_proc;
        int error;
        vm_prot_t prot, maxprot;

        KASSERT(vp->v_iflag & VI_TEXT);

        /*
         * map the vnode in using uvm_map.
         */

        if (cmd->ev_len == 0)
                return 0;
        if (cmd->ev_offset & PAGE_MASK)
                return SET_ERROR(EINVAL);
        if (cmd->ev_addr & PAGE_MASK)
                return SET_ERROR(EINVAL);
        if (cmd->ev_len & PAGE_MASK)
                return SET_ERROR(EINVAL);

        if ((error = vmcmd_get_prot(l, cmd, &prot, &maxprot)) != 0)
                return error;

        /*
         * check the file system's opinion about mmapping the file
         */

        error = VOP_MMAP(vp, prot, l->l_cred);
        if (error)
                return error;

        if ((vp->v_vflag & VV_MAPPED) == 0) {
                vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
                vp->v_vflag |= VV_MAPPED;
                VOP_UNLOCK(vp);
        }

        /*
         * do the map, reference the object for this map entry
         */
        uobj = &vp->v_uobj;
        vref(vp);

        error = uvm_map(&p->p_vmspace->vm_map, &cmd->ev_addr, cmd->ev_len,
                uobj, cmd->ev_offset, 0,
                UVM_MAPFLAG(prot, maxprot, UVM_INH_COPY,
                        UVM_ADV_NORMAL, UVM_FLAG_COPYONW|UVM_FLAG_FIXED));
        if (error) {
                uobj->pgops->pgo_detach(uobj);
        }
        return error;
}

/*
 * vmcmd_map_readvn():
 *      handle vmcmd which specifies that a vnode should be read from.
 *      appropriate for non-demand-paged text/data segments, i.e. impure
 *      objects (a la OMAGIC and NMAGIC).
 */
int
vmcmd_map_readvn(struct lwp *l, struct exec_vmcmd *cmd)
{
        struct proc *p = l->l_proc;
        int error;
        long diff;

        if (cmd->ev_len == 0)
                return 0;

        diff = cmd->ev_addr - trunc_page(cmd->ev_addr);
        cmd->ev_addr -= diff;                   /* required by uvm_map */
        cmd->ev_offset -= diff;
        cmd->ev_len += diff;

        error = uvm_map(&p->p_vmspace->vm_map, &cmd->ev_addr,
                        round_page(cmd->ev_len), NULL, UVM_UNKNOWN_OFFSET, 0,
                        UVM_MAPFLAG(UVM_PROT_ALL, UVM_PROT_ALL, UVM_INH_COPY,
                        UVM_ADV_NORMAL,
                        UVM_FLAG_FIXED|UVM_FLAG_OVERLAY|UVM_FLAG_COPYONW));

        if (error)
                return error;

        return vmcmd_readvn(l, cmd);
}

int
vmcmd_readvn(struct lwp *l, struct exec_vmcmd *cmd)
{
        struct proc *p = l->l_proc;
        int error;
        vm_prot_t prot, maxprot;

        error = vn_rdwr(UIO_READ, cmd->ev_vp, (void *)cmd->ev_addr,
            cmd->ev_len, cmd->ev_offset, UIO_USERSPACE, IO_UNIT,
            l->l_cred, NULL, l);
        if (error)
                return error;

        if ((error = vmcmd_get_prot(l, cmd, &prot, &maxprot)) != 0)
                return error;

#ifdef PMAP_NEED_PROCWR
        /*
         * we had to write the process, make sure the pages are synched
         * with the instruction cache.
         */
        if (prot & VM_PROT_EXECUTE)
                pmap_procwr(p, cmd->ev_addr, cmd->ev_len);
#endif

        /*
         * we had to map in the area at PROT_ALL so that vn_rdwr()
         * could write to it.   however, the caller seems to want
         * it mapped read-only, so now we are going to have to call
         * uvm_map_protect() to fix up the protection.  ICK.
         */
        if (maxprot != VM_PROT_ALL) {
                error = uvm_map_protect(&p->p_vmspace->vm_map,
                                trunc_page(cmd->ev_addr),
                                round_page(cmd->ev_addr + cmd->ev_len),
                                maxprot, true);
                if (error)
                        return error;
        }

        if (prot != maxprot) {
                error = uvm_map_protect(&p->p_vmspace->vm_map,
                                trunc_page(cmd->ev_addr),
                                round_page(cmd->ev_addr + cmd->ev_len),
                                prot, false);
                if (error)
                        return error;
        }

        return 0;
}

/*
 * vmcmd_map_zero():
 *      handle vmcmd which specifies a zero-filled address space region.  The
 *      address range must be first allocated, then protected appropriately.
 */

int
vmcmd_map_zero(struct lwp *l, struct exec_vmcmd *cmd)
{
        struct proc *p = l->l_proc;
        int error;
        long diff;
        vm_prot_t prot, maxprot;

        diff = cmd->ev_addr - trunc_page(cmd->ev_addr);
        cmd->ev_addr -= diff;                   /* required by uvm_map */
        cmd->ev_len += diff;

        if ((error = vmcmd_get_prot(l, cmd, &prot, &maxprot)) != 0)
                return error;

        error = uvm_map(&p->p_vmspace->vm_map, &cmd->ev_addr,
                        round_page(cmd->ev_len), NULL, UVM_UNKNOWN_OFFSET, 0,
                        UVM_MAPFLAG(prot, maxprot, UVM_INH_COPY,
                        UVM_ADV_NORMAL,
                        UVM_FLAG_FIXED|UVM_FLAG_COPYONW));
        if (cmd->ev_flags & VMCMD_STACK)
                curproc->p_vmspace->vm_issize += atop(round_page(cmd->ev_len));
        return error;
}

/*
 * exec_read():
 *
 *      Read from vnode into buffer at offset.
 */
int
exec_read(struct lwp *l, struct vnode *vp, u_long off, void *bf, size_t size,
    int ioflg)
{
        int error;
        size_t resid;

        KASSERT((ioflg & IO_NODELOCKED) == 0 || VOP_ISLOCKED(vp) != LK_NONE);

        if ((error = vn_rdwr(UIO_READ, vp, bf, size, off, UIO_SYSSPACE,
            ioflg, l->l_cred, &resid, NULL)) != 0)
                return error;
        /*
         * See if we got all of it
         */
        if (resid != 0)
                return SET_ERROR(ENOEXEC);
        return 0;
}

/*
 * exec_setup_stack(): Set up the stack segment for an elf
 * executable.
 *
 * Note that the ep_ssize parameter must be set to be the current stack
 * limit; this is adjusted in the body of execve() to yield the
 * appropriate stack segment usage once the argument length is
 * calculated.
 *
 * This function returns an int for uniformity with other (future) formats'
 * stack setup functions.  They might have errors to return.
 */

int
exec_setup_stack(struct lwp *l, struct exec_package *epp)
{
        vsize_t max_stack_size;
        vaddr_t access_linear_min;
        vsize_t access_size;
        vaddr_t noaccess_linear_min;
        vsize_t noaccess_size;

#ifndef USRSTACK32
#define USRSTACK32      (0x00000000ffffffffL&~PAGE_MASK)
#endif
#ifndef MAXSSIZ32
#define MAXSSIZ32       (MAXSSIZ >> 2)
#endif

        if (epp->ep_flags & EXEC_32) {
                epp->ep_minsaddr = USRSTACK32;
                max_stack_size = MAXSSIZ32;
        } else {
                epp->ep_minsaddr = USRSTACK;
                max_stack_size = MAXSSIZ;
        }

        DPRINTF(("ep_minsaddr=%#jx max_stack_size=%#jx\n",
            (uintmax_t)epp->ep_minsaddr, (uintmax_t)max_stack_size));

        pax_aslr_stack(epp, &max_stack_size);

        DPRINTF(("[RLIMIT_STACK].lim_cur=%#jx max_stack_size=%#jx\n",
            (uintmax_t)l->l_proc->p_rlimit[RLIMIT_STACK].rlim_cur,
            (uintmax_t)max_stack_size));
        epp->ep_ssize = MIN(l->l_proc->p_rlimit[RLIMIT_STACK].rlim_cur,
            max_stack_size);

        l->l_proc->p_stackbase = epp->ep_minsaddr;

        epp->ep_maxsaddr = (vaddr_t)STACK_GROW(epp->ep_minsaddr,
            max_stack_size);

        DPRINTF(("ep_ssize=%#jx ep_minsaddr=%#jx ep_maxsaddr=%#jx\n",
            (uintmax_t)epp->ep_ssize, (uintmax_t)epp->ep_minsaddr,
            (uintmax_t)epp->ep_maxsaddr));

        /*
         * set up commands for stack.  note that this takes *two*, one to
         * map the part of the stack which we can access, and one to map
         * the part which we can't.
         *
         * arguably, it could be made into one, but that would require the
         * addition of another mapping proc, which is unnecessary
         */
        access_size = epp->ep_ssize;
        access_linear_min = (vaddr_t)STACK_ALLOC(epp->ep_minsaddr, access_size);
        noaccess_size = max_stack_size - access_size;
        noaccess_linear_min = (vaddr_t)STACK_ALLOC(STACK_GROW(epp->ep_minsaddr,
            access_size), noaccess_size);

        DPRINTF(("access_size=%#jx, access_linear_min=%#jx, "
            "noaccess_size=%#jx, noaccess_linear_min=%#jx\n",
            (uintmax_t)access_size, (uintmax_t)access_linear_min,
            (uintmax_t)noaccess_size, (uintmax_t)noaccess_linear_min));

        if (user_stack_guard_size > 0) {
#ifdef __MACHINE_STACK_GROWS_UP
                vsize_t guard_size = MIN(VM_MAXUSER_ADDRESS - epp->ep_maxsaddr, user_stack_guard_size);
                if (guard_size > 0)
                        NEW_VMCMD(&epp->ep_vmcmds, vmcmd_map_zero, guard_size,
                            epp->ep_maxsaddr, NULL, 0, VM_PROT_NONE);
#else
                NEW_VMCMD(&epp->ep_vmcmds, vmcmd_map_zero, user_stack_guard_size,
                    epp->ep_maxsaddr - user_stack_guard_size, NULL, 0, VM_PROT_NONE);
#endif
        }
        if (noaccess_size > 0 && noaccess_size <= MAXSSIZ) {
                NEW_VMCMD2(&epp->ep_vmcmds, vmcmd_map_zero, noaccess_size,
                    noaccess_linear_min, NULL, 0,
                    VM_PROT_NONE | PROT_MPROTECT(VM_PROT_READ | VM_PROT_WRITE),
                    VMCMD_STACK);
        }
        KASSERT(access_size > 0);
        KASSERT(access_size <= MAXSSIZ);
        NEW_VMCMD2(&epp->ep_vmcmds, vmcmd_map_zero, access_size,
            access_linear_min, NULL, 0, VM_PROT_READ | VM_PROT_WRITE,
            VMCMD_STACK);

        return 0;
}