/*-
 * 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/cdefs.h>
#include "opt_capsicum.h"
#include "opt_hwpmc_hooks.h"
#include "opt_hwt_hooks.h"
#include "opt_ktrace.h"
#include "opt_vm.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/acct.h>
#include <sys/asan.h>
#include <sys/capsicum.h>
#include <sys/compressor.h>
#include <sys/eventhandler.h>
#include <sys/exec.h>
#include <sys/fcntl.h>
#include <sys/filedesc.h>
#include <sys/imgact.h>
#include <sys/imgact_elf.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mman.h>
#include <sys/mount.h>
#include <sys/mutex.h>
#include <sys/namei.h>
#include <sys/priv.h>
#include <sys/proc.h>
#include <sys/ptrace.h>
#include <sys/reg.h>
#include <sys/resourcevar.h>
#include <sys/rwlock.h>
#include <sys/sched.h>
#include <sys/sdt.h>
#include <sys/sf_buf.h>
#include <sys/shm.h>
#include <sys/signalvar.h>
#include <sys/smp.h>
#include <sys/stat.h>
#include <sys/syscallsubr.h>
#include <sys/sysctl.h>
#include <sys/sysent.h>
#include <sys/sysproto.h>
#include <sys/timers.h>
#include <sys/ucoredump.h>
#include <sys/umtxvar.h>
#include <sys/vnode.h>
#include <sys/wait.h>
#ifdef KTRACE
#include <sys/ktrace.h>
#endif

#include <vm/vm.h>
#include <vm/vm_param.h>
#include <vm/pmap.h>
#include <vm/vm_page.h>
#include <vm/vm_map.h>
#include <vm/vm_kern.h>
#include <vm/vm_extern.h>
#include <vm/vm_object.h>
#include <vm/vm_pager.h>

#ifdef  HWPMC_HOOKS
#include <sys/pmckern.h>
#endif

#ifdef HWT_HOOKS
#include <dev/hwt/hwt_hook.h>
#endif

#include <security/audit/audit.h>
#include <security/mac/mac_framework.h>

#ifdef KDTRACE_HOOKS
#include <sys/dtrace_bsd.h>
dtrace_execexit_func_t  dtrace_fasttrap_exec;
#endif

SDT_PROVIDER_DECLARE(proc);
SDT_PROBE_DEFINE1(proc, , , exec, "char *");
SDT_PROBE_DEFINE1(proc, , , exec__failure, "int");
SDT_PROBE_DEFINE1(proc, , , exec__success, "char *");

MALLOC_DEFINE(M_PARGS, "proc-args", "Process arguments");

int coredump_pack_fileinfo = 1;
SYSCTL_INT(_kern, OID_AUTO, coredump_pack_fileinfo, CTLFLAG_RWTUN,
    &coredump_pack_fileinfo, 0,
    "Enable file path packing in 'procstat -f' coredump notes");

int coredump_pack_vmmapinfo = 1;
SYSCTL_INT(_kern, OID_AUTO, coredump_pack_vmmapinfo, CTLFLAG_RWTUN,
    &coredump_pack_vmmapinfo, 0,
    "Enable file path packing in 'procstat -v' coredump notes");

static int sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS);
static int sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS);
static int sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS);
static int do_execve(struct thread *td, struct image_args *args,
    struct mac *mac_p, struct vmspace *oldvmspace);

/* XXX This should be vm_size_t. */
SYSCTL_PROC(_kern, KERN_PS_STRINGS, ps_strings, CTLTYPE_ULONG|CTLFLAG_RD|
    CTLFLAG_CAPRD|CTLFLAG_MPSAFE, NULL, 0, sysctl_kern_ps_strings, "LU",
    "Location of process' ps_strings structure");

/* XXX This should be vm_size_t. */
SYSCTL_PROC(_kern, KERN_USRSTACK, usrstack, CTLTYPE_ULONG|CTLFLAG_RD|
    CTLFLAG_CAPRD|CTLFLAG_MPSAFE, NULL, 0, sysctl_kern_usrstack, "LU",
    "Top of process stack");

SYSCTL_PROC(_kern, OID_AUTO, stackprot, CTLTYPE_INT|CTLFLAG_RD|CTLFLAG_MPSAFE,
    NULL, 0, sysctl_kern_stackprot, "I",
    "Stack memory permissions");

u_long ps_arg_cache_limit = PAGE_SIZE / 16;
SYSCTL_ULONG(_kern, OID_AUTO, ps_arg_cache_limit, CTLFLAG_RW, 
    &ps_arg_cache_limit, 0,
    "Process' command line characters cache limit");

static int disallow_high_osrel;
SYSCTL_INT(_kern, OID_AUTO, disallow_high_osrel, CTLFLAG_RW,
    &disallow_high_osrel, 0,
    "Disallow execution of binaries built for higher version of the world");

static int map_at_zero = 0;
SYSCTL_INT(_security_bsd, OID_AUTO, map_at_zero, CTLFLAG_RWTUN, &map_at_zero, 0,
    "Permit processes to map an object at virtual address 0.");

static int core_dump_can_intr = 1;
SYSCTL_INT(_kern, OID_AUTO, core_dump_can_intr, CTLFLAG_RWTUN,
    &core_dump_can_intr, 0,
    "Core dumping interruptible with SIGKILL");

static int
sysctl_kern_ps_strings(SYSCTL_HANDLER_ARGS)
{
        struct proc *p;
        vm_offset_t ps_strings;

        p = curproc;
#ifdef SCTL_MASK32
        if (req->flags & SCTL_MASK32) {
                unsigned int val;
                val = (unsigned int)PROC_PS_STRINGS(p);
                return (SYSCTL_OUT(req, &val, sizeof(val)));
        }
#endif
        ps_strings = PROC_PS_STRINGS(p);
        return (SYSCTL_OUT(req, &ps_strings, sizeof(ps_strings)));
}

static int
sysctl_kern_usrstack(SYSCTL_HANDLER_ARGS)
{
        struct proc *p;
        vm_offset_t val;

        p = curproc;
#ifdef SCTL_MASK32
        if (req->flags & SCTL_MASK32) {
                unsigned int val32;

                val32 = round_page((unsigned int)p->p_vmspace->vm_stacktop);
                return (SYSCTL_OUT(req, &val32, sizeof(val32)));
        }
#endif
        val = round_page(p->p_vmspace->vm_stacktop);
        return (SYSCTL_OUT(req, &val, sizeof(val)));
}

static int
sysctl_kern_stackprot(SYSCTL_HANDLER_ARGS)
{
        struct proc *p;

        p = curproc;
        return (SYSCTL_OUT(req, &p->p_sysent->sv_stackprot,
            sizeof(p->p_sysent->sv_stackprot)));
}

/*
 * Each of the items is a pointer to a `const struct execsw', hence the
 * double pointer here.
 */
static const struct execsw **execsw;

#ifndef _SYS_SYSPROTO_H_
struct execve_args {
        char    *fname;
        char    **argv;
        char    **envv;
};
#endif

int
sys_execve(struct thread *td, struct execve_args *uap)
{
        struct image_args args;
        struct vmspace *oldvmspace;
        int error;

        error = pre_execve(td, &oldvmspace);
        if (error != 0)
                return (error);
        error = exec_copyin_args(&args, uap->fname, uap->argv, uap->envv);
        if (error == 0)
                error = kern_execve(td, &args, NULL, oldvmspace);
        post_execve(td, error, oldvmspace);
        AUDIT_SYSCALL_EXIT(error == EJUSTRETURN ? 0 : error, td);
        return (error);
}

#ifndef _SYS_SYSPROTO_H_
struct fexecve_args {
        int     fd;
        char    **argv;
        char    **envv;
};
#endif
int
sys_fexecve(struct thread *td, struct fexecve_args *uap)
{
        struct image_args args;
        struct vmspace *oldvmspace;
        int error;

        error = pre_execve(td, &oldvmspace);
        if (error != 0)
                return (error);
        error = exec_copyin_args(&args, NULL, uap->argv, uap->envv);
        if (error == 0) {
                args.fd = uap->fd;
                error = kern_execve(td, &args, NULL, oldvmspace);
        }
        post_execve(td, error, oldvmspace);
        AUDIT_SYSCALL_EXIT(error == EJUSTRETURN ? 0 : error, td);
        return (error);
}

#ifndef _SYS_SYSPROTO_H_
struct __mac_execve_args {
        char    *fname;
        char    **argv;
        char    **envv;
        struct mac      *mac_p;
};
#endif

int
sys___mac_execve(struct thread *td, struct __mac_execve_args *uap)
{
#ifdef MAC
        struct image_args args;
        struct vmspace *oldvmspace;
        int error;

        error = pre_execve(td, &oldvmspace);
        if (error != 0)
                return (error);
        error = exec_copyin_args(&args, uap->fname, uap->argv, uap->envv);
        if (error == 0)
                error = kern_execve(td, &args, uap->mac_p, oldvmspace);
        post_execve(td, error, oldvmspace);
        AUDIT_SYSCALL_EXIT(error == EJUSTRETURN ? 0 : error, td);
        return (error);
#else
        return (ENOSYS);
#endif
}

int
pre_execve(struct thread *td, struct vmspace **oldvmspace)
{
        struct proc *p;
        int error;

        KASSERT(td == curthread, ("non-current thread %p", td));
        error = 0;
        p = td->td_proc;
        if ((p->p_flag & P_HADTHREADS) != 0) {
                PROC_LOCK(p);
                if (thread_single(p, SINGLE_BOUNDARY) != 0)
                        error = ERESTART;
                PROC_UNLOCK(p);
        }
        KASSERT(error != 0 || (td->td_pflags & TDP_EXECVMSPC) == 0,
            ("nested execve"));
        *oldvmspace = p->p_vmspace;
        return (error);
}

void
post_execve(struct thread *td, int error, struct vmspace *oldvmspace)
{
        struct proc *p;

        KASSERT(td == curthread, ("non-current thread %p", td));
        p = td->td_proc;
        if ((p->p_flag & P_HADTHREADS) != 0) {
                PROC_LOCK(p);
                /*
                 * If success, we upgrade to SINGLE_EXIT state to
                 * force other threads to suicide.
                 */
                if (error == EJUSTRETURN)
                        thread_single(p, SINGLE_EXIT);
                else
                        thread_single_end(p, SINGLE_BOUNDARY);
                PROC_UNLOCK(p);
        }
        exec_cleanup(td, oldvmspace);
}

/*
 * kern_execve() has the astonishing property of not always returning to
 * the caller.  If sufficiently bad things happen during the call to
 * do_execve(), it can end up calling exit1(); as a result, callers must
 * avoid doing anything which they might need to undo (e.g., allocating
 * memory).
 */
int
kern_execve(struct thread *td, struct image_args *args, struct mac *mac_p,
    struct vmspace *oldvmspace)
{

        TSEXEC(td->td_proc->p_pid, args->begin_argv);
        AUDIT_ARG_ARGV(args->begin_argv, args->argc,
            exec_args_get_begin_envv(args) - args->begin_argv);
        AUDIT_ARG_ENVV(exec_args_get_begin_envv(args), args->envc,
            args->endp - exec_args_get_begin_envv(args));
#ifdef KTRACE
        if (KTRPOINT(td, KTR_ARGS)) {
                ktrdata(KTR_ARGS, args->begin_argv,
                    exec_args_get_begin_envv(args) - args->begin_argv);
        }
        if (KTRPOINT(td, KTR_ENVS)) {
                ktrdata(KTR_ENVS, exec_args_get_begin_envv(args),
                    args->endp - exec_args_get_begin_envv(args));
        }
#endif
        /* Must have at least one argument. */
        if (args->argc == 0) {
                exec_free_args(args);
                return (EINVAL);
        }
        return (do_execve(td, args, mac_p, oldvmspace));
}

static void
execve_nosetid(struct image_params *imgp)
{
        imgp->credential_setid = false;
        if (imgp->newcred != NULL) {
                crfree(imgp->newcred);
                imgp->newcred = NULL;
        }
}

/*
 * In-kernel implementation of execve().  All arguments are assumed to be
 * userspace pointers from the passed thread.
 */
static int
do_execve(struct thread *td, struct image_args *args, struct mac *mac_p,
    struct vmspace *oldvmspace)
{
        struct proc *p = td->td_proc;
        struct nameidata nd;
        struct ucred *oldcred;
        struct uidinfo *euip = NULL;
        uintptr_t stack_base;
        struct image_params image_params, *imgp;
        struct vattr attr;
        struct pargs *oldargs = NULL, *newargs = NULL;
        struct sigacts *oldsigacts = NULL, *newsigacts = NULL;
#ifdef KTRACE
        struct ktr_io_params *kiop;
#endif
        struct vnode *oldtextvp, *newtextvp;
        struct vnode *oldtextdvp, *newtextdvp;
        char *oldbinname, *newbinname;
        bool credential_changing;
#ifdef MAC
        struct label *interpvplabel = NULL;
        bool will_transition;
#endif
#ifdef HWPMC_HOOKS
        struct pmckern_procexec pe;
#endif
        int error, i, orig_osrel;
        uint32_t orig_fctl0;
        const Elf_Brandinfo *orig_brandinfo;
        size_t freepath_size;
        static const char fexecv_proc_title[] = "(fexecv)";

        imgp = &image_params;
        oldtextvp = oldtextdvp = NULL;
        newtextvp = newtextdvp = NULL;
        newbinname = oldbinname = NULL;
#ifdef KTRACE
        kiop = NULL;
#endif

        /*
         * Lock the process and set the P_INEXEC flag to indicate that
         * it should be left alone until we're done here.  This is
         * necessary to avoid race conditions - e.g. in ptrace() -
         * that might allow a local user to illicitly obtain elevated
         * privileges.
         */
        PROC_LOCK(p);
        KASSERT((p->p_flag & P_INEXEC) == 0,
            ("%s(): process already has P_INEXEC flag", __func__));
        p->p_flag |= P_INEXEC;
        PROC_UNLOCK(p);

        /*
         * Initialize part of the common data
         */
        bzero(imgp, sizeof(*imgp));
        imgp->proc = p;
        imgp->attr = &attr;
        imgp->args = args;
        oldcred = p->p_ucred;
        orig_osrel = p->p_osrel;
        orig_fctl0 = p->p_fctl0;
        orig_brandinfo = p->p_elf_brandinfo;

#ifdef MAC
        error = mac_execve_enter(imgp, mac_p);
        if (error)
                goto exec_fail;
#endif

        SDT_PROBE1(proc, , , exec, args->fname);

interpret:
        if (args->fname != NULL) {
#ifdef CAPABILITY_MODE
                if (CAP_TRACING(td))
                        ktrcapfail(CAPFAIL_NAMEI, args->fname);
                /*
                 * While capability mode can't reach this point via direct
                 * path arguments to execve(), we also don't allow
                 * interpreters to be used in capability mode (for now).
                 * Catch indirect lookups and return a permissions error.
                 */
                if (IN_CAPABILITY_MODE(td)) {
                        error = ECAPMODE;
                        goto exec_fail;
                }
#endif

                /*
                 * Translate the file name. namei() returns a vnode
                 * pointer in ni_vp among other things.
                 */
                NDINIT(&nd, LOOKUP, ISOPEN | LOCKLEAF | LOCKSHARED | FOLLOW |
                    AUDITVNODE1 | WANTPARENT, UIO_SYSSPACE,
                    args->fname);

                error = namei(&nd);
                if (error)
                        goto exec_fail;

                newtextvp = nd.ni_vp;
                newtextdvp = nd.ni_dvp;
                nd.ni_dvp = NULL;
                newbinname = malloc(nd.ni_cnd.cn_namelen + 1, M_PARGS,
                    M_WAITOK);
                memcpy(newbinname, nd.ni_cnd.cn_nameptr, nd.ni_cnd.cn_namelen);
                newbinname[nd.ni_cnd.cn_namelen] = '\0';
                imgp->vp = newtextvp;

                /*
                 * Do the best to calculate the full path to the image file.
                 */
                if (args->fname[0] == '/') {
                        imgp->execpath = args->fname;
                } else {
                        VOP_UNLOCK(imgp->vp);
                        freepath_size = MAXPATHLEN;
                        if (vn_fullpath_hardlink(newtextvp, newtextdvp,
                            newbinname, nd.ni_cnd.cn_namelen, &imgp->execpath,
                            &imgp->freepath, &freepath_size) != 0)
                                imgp->execpath = args->fname;
                        vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
                }
        } else if (imgp->interpreter_vp) {
                /*
                 * An image activator has already provided an open vnode
                 */
                newtextvp = imgp->interpreter_vp;
                imgp->interpreter_vp = NULL;
                if (vn_fullpath(newtextvp, &imgp->execpath,
                    &imgp->freepath) != 0)
                        imgp->execpath = args->fname;
                vn_lock(newtextvp, LK_SHARED | LK_RETRY);
                AUDIT_ARG_VNODE1(newtextvp);
                imgp->vp = newtextvp;
        } else {
                AUDIT_ARG_FD(args->fd);

                /*
                 * If the descriptors was not opened with O_PATH, then
                 * we require that it was opened with O_EXEC or
                 * O_RDONLY.  In either case, exec_check_permissions()
                 * below checks _current_ file access mode regardless
                 * of the permissions additionally checked at the
                 * open(2).
                 */
                error = fgetvp_exec(td, args->fd, &cap_fexecve_rights,
                    &newtextvp);
                if (error != 0)
                        goto exec_fail;

                if (vn_fullpath(newtextvp, &imgp->execpath,
                    &imgp->freepath) != 0)
                        imgp->execpath = args->fname;
                vn_lock(newtextvp, LK_SHARED | LK_RETRY);
                AUDIT_ARG_VNODE1(newtextvp);
                imgp->vp = newtextvp;
        }

        /*
         * Check file permissions.  Also 'opens' file and sets its vnode to
         * text mode.
         */
        error = exec_check_permissions(imgp);
        if (error)
                goto exec_fail_dealloc;

        imgp->object = imgp->vp->v_object;
        if (imgp->object != NULL)
                vm_object_reference(imgp->object);

        error = exec_map_first_page(imgp);
        if (error)
                goto exec_fail_dealloc;

        imgp->proc->p_osrel = 0;
        imgp->proc->p_fctl0 = 0;
        imgp->proc->p_elf_brandinfo = NULL;

        /*
         * Implement image setuid/setgid.
         *
         * Determine new credentials before attempting image activators
         * so that it can be used by process_exec handlers to determine
         * credential/setid changes.
         *
         * Don't honor setuid/setgid if the filesystem prohibits it or if
         * the process is being traced.
         *
         * We disable setuid/setgid/etc in capability mode on the basis
         * that most setugid applications are not written with that
         * environment in mind, and will therefore almost certainly operate
         * incorrectly. In principle there's no reason that setugid
         * applications might not be useful in capability mode, so we may want
         * to reconsider this conservative design choice in the future.
         *
         * XXXMAC: For the time being, use NOSUID to also prohibit
         * transitions on the file system.
         */
        credential_changing = false;
        credential_changing |= (attr.va_mode & S_ISUID) &&
            oldcred->cr_uid != attr.va_uid;
        credential_changing |= (attr.va_mode & S_ISGID) &&
            oldcred->cr_gid != attr.va_gid;
#ifdef MAC
        will_transition = mac_vnode_execve_will_transition(oldcred, imgp->vp,
            interpvplabel, imgp) != 0;
        credential_changing |= will_transition;
#endif

        /* Don't inherit PROC_PDEATHSIG_CTL value if setuid/setgid. */
        if (credential_changing)
                imgp->proc->p_pdeathsig = 0;

        if (credential_changing &&
#ifdef CAPABILITY_MODE
            ((oldcred->cr_flags & CRED_FLAG_CAPMODE) == 0) &&
#endif
            (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 &&
            (p->p_flag & P_TRACED) == 0) {
                imgp->credential_setid = true;
                VOP_UNLOCK(imgp->vp);
                imgp->newcred = crdup(oldcred);
                if (attr.va_mode & S_ISUID) {
                        euip = uifind(attr.va_uid);
                        change_euid(imgp->newcred, euip);
                }
                vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
                if (attr.va_mode & S_ISGID)
                        change_egid(imgp->newcred, attr.va_gid);
                /*
                 * Implement correct POSIX saved-id behavior.
                 *
                 * XXXMAC: Note that the current logic will save the
                 * uid and gid if a MAC domain transition occurs, even
                 * though maybe it shouldn't.
                 */
                change_svuid(imgp->newcred, imgp->newcred->cr_uid);
                change_svgid(imgp->newcred, imgp->newcred->cr_gid);
        } else {
                /*
                 * Implement correct POSIX saved-id behavior.
                 *
                 * XXX: It's not clear that the existing behavior is
                 * POSIX-compliant.  A number of sources indicate that the
                 * saved uid/gid should only be updated if the new ruid is
                 * not equal to the old ruid, or the new euid is not equal
                 * to the old euid and the new euid is not equal to the old
                 * ruid.  The FreeBSD code always updates the saved uid/gid.
                 * Also, this code uses the new (replaced) euid and egid as
                 * the source, which may or may not be the right ones to use.
                 */
                if (oldcred->cr_svuid != oldcred->cr_uid ||
                    oldcred->cr_svgid != oldcred->cr_gid) {
                        VOP_UNLOCK(imgp->vp);
                        imgp->newcred = crdup(oldcred);
                        vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
                        change_svuid(imgp->newcred, imgp->newcred->cr_uid);
                        change_svgid(imgp->newcred, imgp->newcred->cr_gid);
                }
        }
        /* The new credentials are installed into the process later. */

        /*
         *      Loop through the list of image activators, calling each one.
         *      An activator returns -1 if there is no match, 0 on success,
         *      and an error otherwise.
         */
        error = -1;
        for (i = 0; error == -1 && execsw[i]; ++i) {
                if (execsw[i]->ex_imgact == NULL)
                        continue;
                error = (*execsw[i]->ex_imgact)(imgp);
        }

        if (error) {
                if (error == -1)
                        error = ENOEXEC;
                goto exec_fail_dealloc;
        }

        /*
         * Special interpreter operation, cleanup and loop up to try to
         * activate the interpreter.
         */
        if (imgp->interpreted) {
                exec_unmap_first_page(imgp);
                /*
                 * The text reference needs to be removed for scripts.
                 * There is a short period before we determine that
                 * something is a script where text reference is active.
                 * The vnode lock is held over this entire period
                 * so nothing should illegitimately be blocked.
                 */
                MPASS(imgp->textset);
                VOP_UNSET_TEXT_CHECKED(newtextvp);
                imgp->textset = false;
                /* free name buffer and old vnode */
#ifdef MAC
                mac_execve_interpreter_enter(newtextvp, &interpvplabel);
#endif
                if (imgp->opened) {
                        VOP_CLOSE(newtextvp, FREAD, td->td_ucred, td);
                        imgp->opened = false;
                }
                vput(newtextvp);
                imgp->vp = newtextvp = NULL;
                if (args->fname != NULL) {
                        if (newtextdvp != NULL) {
                                vrele(newtextdvp);
                                newtextdvp = NULL;
                        }
                        NDFREE_PNBUF(&nd);
                        free(newbinname, M_PARGS);
                        newbinname = NULL;
                }
                vm_object_deallocate(imgp->object);
                imgp->object = NULL;
                execve_nosetid(imgp);
                imgp->execpath = NULL;
                free(imgp->freepath, M_TEMP);
                imgp->freepath = NULL;
                /* set new name to that of the interpreter */
                if (imgp->interpreter_vp) {
                        args->fname = NULL;
                } else {
                        args->fname = imgp->interpreter_name;
                }
                goto interpret;
        }

        /*
         * NB: We unlock the vnode here because it is believed that none
         * of the sv_copyout_strings/sv_fixup operations require the vnode.
         */
        VOP_UNLOCK(imgp->vp);

        if (disallow_high_osrel &&
            P_OSREL_MAJOR(p->p_osrel) > P_OSREL_MAJOR(__FreeBSD_version)) {
                error = ENOEXEC;
                uprintf("Osrel %d for image %s too high\n", p->p_osrel,
                    imgp->execpath != NULL ? imgp->execpath : "<unresolved>");
                vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
                goto exec_fail_dealloc;
        }

        /*
         * Copy out strings (args and env) and initialize stack base.
         */
        error = (*p->p_sysent->sv_copyout_strings)(imgp, &stack_base);
        if (error != 0) {
                vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
                goto exec_fail_dealloc;
        }

        /*
         * Stack setup.
         */
        error = (*p->p_sysent->sv_fixup)(&stack_base, imgp);
        if (error != 0) {
                vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
                goto exec_fail_dealloc;
        }

        /*
         * For security and other reasons, the file descriptor table cannot be
         * shared after an exec.
         */
        fdunshare(td);
        pdunshare(td);
        /* close files on exec */
        fdcloseexec(td);

        /*
         * Malloc things before we need locks.
         */
        i = exec_args_get_begin_envv(imgp->args) - imgp->args->begin_argv;
        /* Cache arguments if they fit inside our allowance */
        if (ps_arg_cache_limit >= i + sizeof(struct pargs)) {
                newargs = pargs_alloc(i);
                bcopy(imgp->args->begin_argv, newargs->ar_args, i);
        }

        /*
         * For security and other reasons, signal handlers cannot
         * be shared after an exec. The new process gets a copy of the old
         * handlers. In execsigs(), the new process will have its signals
         * reset.
         */
        if (sigacts_shared(p->p_sigacts)) {
                oldsigacts = p->p_sigacts;
                newsigacts = sigacts_alloc();
                sigacts_copy(newsigacts, oldsigacts);
        }

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

        PROC_LOCK(p);
        if (oldsigacts)
                p->p_sigacts = newsigacts;
        /* Stop profiling */
        stopprofclock(p);

        /* reset caught signals */
        execsigs(p);

        /* name this process - nameiexec(p, ndp) */
        bzero(p->p_comm, sizeof(p->p_comm));
        if (args->fname)
                bcopy(nd.ni_cnd.cn_nameptr, p->p_comm,
                    min(nd.ni_cnd.cn_namelen, MAXCOMLEN));
        else if (vn_commname(newtextvp, p->p_comm, sizeof(p->p_comm)) != 0)
                bcopy(fexecv_proc_title, p->p_comm, sizeof(fexecv_proc_title));
        bcopy(p->p_comm, td->td_name, sizeof(td->td_name));
#ifdef KTR
        sched_clear_tdname(td);
#endif

        /*
         * mark as execed, wakeup the process that vforked (if any) and tell
         * it that it now has its own resources back
         */
        p->p_flag |= P_EXEC;
        td->td_pflags2 &= ~TDP2_UEXTERR;
        if ((p->p_flag2 & P2_NOTRACE_EXEC) == 0)
                p->p_flag2 &= ~P2_NOTRACE;
        if ((p->p_flag2 & P2_STKGAP_DISABLE_EXEC) == 0)
                p->p_flag2 &= ~P2_STKGAP_DISABLE;
        p->p_flag2 &= ~(P2_MEMBAR_PRIVE | P2_MEMBAR_PRIVE_SYNCORE |
            P2_MEMBAR_GLOBE);
        if (p->p_flag & P_PPWAIT) {
                p->p_flag &= ~(P_PPWAIT | P_PPTRACE);
                cv_broadcast(&p->p_pwait);
                /* STOPs are no longer ignored, arrange for AST */
                signotify(td);
        }

        if ((imgp->sysent->sv_setid_allowed != NULL &&
            !(*imgp->sysent->sv_setid_allowed)(td, imgp)) ||
            (p->p_flag2 & P2_NO_NEW_PRIVS) != 0)
                execve_nosetid(imgp);

        /*
         * Implement image setuid/setgid installation.
         */
        if (imgp->credential_setid) {
                /*
                 * Turn off syscall tracing for set-id programs, except for
                 * root.  Record any set-id flags first to make sure that
                 * we do not regain any tracing during a possible block.
                 */
                setsugid(p);
#ifdef KTRACE
                kiop = ktrprocexec(p);
#endif
                /*
                 * Close any file descriptors 0..2 that reference procfs,
                 * then make sure file descriptors 0..2 are in use.
                 *
                 * Both fdsetugidsafety() and fdcheckstd() may call functions
                 * taking sleepable locks, so temporarily drop our locks.
                 */
                PROC_UNLOCK(p);
                VOP_UNLOCK(imgp->vp);
                fdsetugidsafety(td);
                error = fdcheckstd(td);
                vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
                if (error != 0)
                        goto exec_fail_dealloc;
                PROC_LOCK(p);
#ifdef MAC
                if (will_transition) {
                        mac_vnode_execve_transition(oldcred, imgp->newcred,
                            imgp->vp, interpvplabel, imgp);
                }
#endif
        } else {
                if (oldcred->cr_uid == oldcred->cr_ruid &&
                    oldcred->cr_gid == oldcred->cr_rgid)
                        p->p_flag &= ~P_SUGID;
        }
        /*
         * Set the new credentials.
         */
        if (imgp->newcred != NULL) {
                proc_set_cred(p, imgp->newcred);
                crfree(oldcred);
                oldcred = NULL;
        }

        /*
         * Store the vp for use in kern.proc.pathname.  This vnode was
         * referenced by namei() or by fexecve variant of fname handling.
         */
        oldtextvp = p->p_textvp;
        p->p_textvp = newtextvp;
        oldtextdvp = p->p_textdvp;
        p->p_textdvp = newtextdvp;
        newtextdvp = NULL;
        oldbinname = p->p_binname;
        p->p_binname = newbinname;
        newbinname = NULL;

#ifdef KDTRACE_HOOKS
        /*
         * Tell the DTrace fasttrap provider about the exec if it
         * has declared an interest.
         */
        if (dtrace_fasttrap_exec)
                dtrace_fasttrap_exec(p);
#endif

        /*
         * Notify others that we exec'd, and clear the P_INEXEC flag
         * as we're now a bona fide freshly-execed process.
         */
        KNOTE_LOCKED(p->p_klist, NOTE_EXEC);
        p->p_flag &= ~P_INEXEC;

        /* clear "fork but no exec" flag, as we _are_ execing */
        p->p_acflag &= ~AFORK;

        /*
         * Free any previous argument cache and replace it with
         * the new argument cache, if any.
         */
        oldargs = p->p_args;
        p->p_args = newargs;
        newargs = NULL;

        PROC_UNLOCK(p);

#ifdef  HWPMC_HOOKS
        /*
         * Check if system-wide sampling is in effect or if the
         * current process is using PMCs.  If so, do exec() time
         * processing.  This processing needs to happen AFTER the
         * P_INEXEC flag is cleared.
         */
        if (PMC_SYSTEM_SAMPLING_ACTIVE() || PMC_PROC_IS_USING_PMCS(p)) {
                VOP_UNLOCK(imgp->vp);
                pe.pm_credentialschanged = credential_changing;
                pe.pm_baseaddr = imgp->reloc_base;
                pe.pm_dynaddr = imgp->et_dyn_addr;

                PMC_CALL_HOOK_X(td, PMC_FN_PROCESS_EXEC, (void *) &pe);
                vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
        }
#endif

#ifdef HWT_HOOKS
        if ((td->td_proc->p_flag2 & P2_HWT) != 0) {
                struct hwt_record_entry ent;

                VOP_UNLOCK(imgp->vp);
                ent.fullpath = imgp->execpath;
                ent.addr = imgp->et_dyn_addr;
                ent.baseaddr = imgp->reloc_base;
                ent.record_type = HWT_RECORD_EXECUTABLE;
                HWT_CALL_HOOK(td, HWT_EXEC, &ent);
                vn_lock(imgp->vp, LK_SHARED | LK_RETRY);
        }
#endif

        /* Set values passed into the program in registers. */
        (*p->p_sysent->sv_setregs)(td, imgp, stack_base);

        VOP_MMAPPED(imgp->vp);

        SDT_PROBE1(proc, , , exec__success, args->fname);

exec_fail_dealloc:
        if (error != 0) {
                p->p_osrel = orig_osrel;
                p->p_fctl0 = orig_fctl0;
                p->p_elf_brandinfo = orig_brandinfo;
        }

        if (imgp->firstpage != NULL)
                exec_unmap_first_page(imgp);

        if (imgp->vp != NULL) {
                if (imgp->opened)
                        VOP_CLOSE(imgp->vp, FREAD, td->td_ucred, td);
                if (imgp->textset)
                        VOP_UNSET_TEXT_CHECKED(imgp->vp);
                if (error != 0)
                        vput(imgp->vp);
                else
                        VOP_UNLOCK(imgp->vp);
                if (args->fname != NULL)
                        NDFREE_PNBUF(&nd);
                if (newtextdvp != NULL)
                        vrele(newtextdvp);
                free(newbinname, M_PARGS);
        }

        if (imgp->object != NULL)
                vm_object_deallocate(imgp->object);

        free(imgp->freepath, M_TEMP);

        if (error == 0) {
                if (p->p_ptevents & PTRACE_EXEC) {
                        PROC_LOCK(p);
                        if (p->p_ptevents & PTRACE_EXEC)
                                td->td_dbgflags |= TDB_EXEC;
                        PROC_UNLOCK(p);
                }
        } else {
exec_fail:
                /* we're done here, clear P_INEXEC */
                PROC_LOCK(p);
                p->p_flag &= ~P_INEXEC;
                PROC_UNLOCK(p);

                SDT_PROBE1(proc, , , exec__failure, error);
        }

        if (imgp->newcred != NULL && oldcred != NULL)
                crfree(imgp->newcred);

#ifdef MAC
        mac_execve_exit(imgp);
        mac_execve_interpreter_exit(interpvplabel);
#endif
        exec_free_args(args);

        /*
         * Handle deferred decrement of ref counts.
         */
        if (oldtextvp != NULL)
                vrele(oldtextvp);
        if (oldtextdvp != NULL)
                vrele(oldtextdvp);
        free(oldbinname, M_PARGS);
#ifdef KTRACE
        ktr_io_params_free(kiop);
#endif
        pargs_drop(oldargs);
        pargs_drop(newargs);
        if (oldsigacts != NULL)
                sigacts_free(oldsigacts);
        if (euip != NULL)
                uifree(euip);

        if (error && imgp->vmspace_destroyed) {
                /* sorry, no more process anymore. exit gracefully */
                exec_cleanup(td, oldvmspace);
                exit1(td, 0, SIGABRT);
                /* NOT REACHED */
        }

#ifdef KTRACE
        if (error == 0)
                ktrprocctor(p);
#endif

        /*
         * We don't want cpu_set_syscall_retval() to overwrite any of
         * the register values put in place by exec_setregs().
         * Implementations of cpu_set_syscall_retval() will leave
         * registers unmodified when returning EJUSTRETURN.
         */
        return (error == 0 ? EJUSTRETURN : error);
}

void
exec_cleanup(struct thread *td, struct vmspace *oldvmspace)
{
        if ((td->td_pflags & TDP_EXECVMSPC) != 0) {
                KASSERT(td->td_proc->p_vmspace != oldvmspace,
                    ("oldvmspace still used"));
                vmspace_free(oldvmspace);
                td->td_pflags &= ~TDP_EXECVMSPC;
        }
}

int
exec_map_first_page(struct image_params *imgp)
{
        vm_object_t object;
        vm_page_t m;
        int error;

        if (imgp->firstpage != NULL)
                exec_unmap_first_page(imgp);

        object = imgp->vp->v_object;
        if (object == NULL)
                return (EACCES);
#if VM_NRESERVLEVEL > 0
        if ((object->flags & OBJ_COLORED) == 0) {
                VM_OBJECT_WLOCK(object);
                vm_object_color(object, 0);
                VM_OBJECT_WUNLOCK(object);
        }
#endif
        error = vm_page_grab_valid_unlocked(&m, object, 0,
            VM_ALLOC_COUNT(VM_INITIAL_PAGEIN) |
            VM_ALLOC_NORMAL | VM_ALLOC_NOBUSY | VM_ALLOC_WIRED);

        if (error != VM_PAGER_OK)
                return (EIO);
        imgp->firstpage = sf_buf_alloc(m, 0);
        imgp->image_header = (char *)sf_buf_kva(imgp->firstpage);

        return (0);
}

void
exec_unmap_first_page(struct image_params *imgp)
{
        vm_page_t m;

        if (imgp->firstpage != NULL) {
                m = sf_buf_page(imgp->firstpage);
                sf_buf_free(imgp->firstpage);
                imgp->firstpage = NULL;
                vm_page_unwire(m, PQ_ACTIVE);
        }
}

void
exec_onexec_old(struct thread *td)
{
        sigfastblock_clear(td);
        umtx_exec(td->td_proc);
}

/*
 * This is an optimization which removes the unmanaged shared page
 * mapping. In combination with pmap_remove_pages(), which cleans all
 * managed mappings in the process' vmspace pmap, no work will be left
 * for pmap_remove(min, max).
 */
void
exec_free_abi_mappings(struct proc *p)
{
        struct vmspace *vmspace;

        vmspace = p->p_vmspace;
        if (refcount_load(&vmspace->vm_refcnt) != 1)
                return;

        if (!PROC_HAS_SHP(p))
                return;

        pmap_remove(vmspace_pmap(vmspace), vmspace->vm_shp_base,
            vmspace->vm_shp_base + p->p_sysent->sv_shared_page_len);
}

/*
 * Run down the current address space and install a new one.
 */
int
exec_new_vmspace(struct image_params *imgp, struct sysentvec *sv)
{
        int error;
        struct proc *p = imgp->proc;
        struct vmspace *vmspace = p->p_vmspace;
        struct thread *td = curthread;
        vm_offset_t sv_minuser;
        vm_map_t map;

        imgp->vmspace_destroyed = true;
        imgp->sysent = sv;

        if (p->p_sysent->sv_onexec_old != NULL)
                p->p_sysent->sv_onexec_old(td);
        itimers_exec(p);

        EVENTHANDLER_DIRECT_INVOKE(process_exec, p, imgp);

        /*
         * Blow away entire process VM, if address space not shared,
         * otherwise, create a new VM space so that other threads are
         * not disrupted
         */
        map = &vmspace->vm_map;
        if (map_at_zero)
                sv_minuser = sv->sv_minuser;
        else
                sv_minuser = MAX(sv->sv_minuser, PAGE_SIZE);
        if (refcount_load(&vmspace->vm_refcnt) == 1 &&
            vm_map_min(map) == sv_minuser &&
            vm_map_max(map) == sv->sv_maxuser &&
            cpu_exec_vmspace_reuse(p, map)) {
                exec_free_abi_mappings(p);
                shmexit(vmspace);
                pmap_remove_pages(vmspace_pmap(vmspace));
                vm_map_remove(map, vm_map_min(map), vm_map_max(map));
                /*
                 * An exec terminates mlockall(MCL_FUTURE).
                 * ASLR and W^X states must be re-evaluated.
                 */
                vm_map_lock(map);
                vm_map_modflags(map, 0, MAP_WIREFUTURE | MAP_ASLR |
                    MAP_ASLR_IGNSTART | MAP_ASLR_STACK | MAP_WXORX);
                vm_map_unlock(map);
        } else {
                error = vmspace_exec(p, sv_minuser, sv->sv_maxuser);
                if (error)
                        return (error);
                vmspace = p->p_vmspace;
                map = &vmspace->vm_map;
        }
        map->flags |= imgp->map_flags;

        return (sv->sv_onexec != NULL ? sv->sv_onexec(p, imgp) : 0);
}

/*
 * Compute the stack size limit and map the main process stack.
 * Map the shared page.
 */
int
exec_map_stack(struct image_params *imgp)
{
        struct rlimit rlim_stack;
        struct sysentvec *sv;
        struct proc *p;
        vm_map_t map;
        struct vmspace *vmspace;
        vm_offset_t stack_addr, stack_top;
        vm_offset_t sharedpage_addr;
        u_long ssiz;
        int error, find_space, stack_off;
        vm_prot_t stack_prot;
        vm_object_t obj;

        p = imgp->proc;
        sv = p->p_sysent;

        if (imgp->stack_sz != 0) {
                ssiz = trunc_page(imgp->stack_sz);
                PROC_LOCK(p);
                lim_rlimit_proc(p, RLIMIT_STACK, &rlim_stack);
                PROC_UNLOCK(p);
                if (ssiz > rlim_stack.rlim_max)
                        ssiz = rlim_stack.rlim_max;
                if (ssiz > rlim_stack.rlim_cur) {
                        rlim_stack.rlim_cur = ssiz;
                        kern_setrlimit(curthread, RLIMIT_STACK, &rlim_stack);
                }
        } else if (sv->sv_maxssiz != NULL) {
                ssiz = *sv->sv_maxssiz;
        } else {
                ssiz = maxssiz;
        }

        vmspace = p->p_vmspace;
        map = &vmspace->vm_map;

        stack_prot = sv->sv_shared_page_obj != NULL && imgp->stack_prot != 0 ?
            imgp->stack_prot : sv->sv_stackprot;
        if ((map->flags & MAP_ASLR_STACK) != 0) {
                stack_addr = round_page((vm_offset_t)p->p_vmspace->vm_daddr +
                    lim_max(curthread, RLIMIT_DATA));
                find_space = VMFS_ANY_SPACE;
        } else {
                stack_addr = sv->sv_usrstack - ssiz;
                find_space = VMFS_NO_SPACE;
        }
        error = vm_map_find(map, NULL, 0, &stack_addr, (vm_size_t)ssiz,
            sv->sv_usrstack, find_space, stack_prot, VM_PROT_ALL,
            MAP_STACK_AREA);
        if (error != KERN_SUCCESS) {
                uprintf("exec_new_vmspace: mapping stack size %#jx prot %#x "
                    "failed, mach error %d errno %d\n", (uintmax_t)ssiz,
                    stack_prot, error, vm_mmap_to_errno(error));
                return (vm_mmap_to_errno(error));
        }

        stack_top = stack_addr + ssiz;
        if ((map->flags & MAP_ASLR_STACK) != 0) {
                /* Randomize within the first page of the stack. */
                arc4rand(&stack_off, sizeof(stack_off), 0);
                stack_top -= rounddown2(stack_off & PAGE_MASK, sizeof(void *));
        }

        /* Map a shared page */
        obj = sv->sv_shared_page_obj;
        if (obj == NULL) {
                sharedpage_addr = 0;
                goto out;
        }

        /*
         * If randomization is disabled then the shared page will
         * be mapped at address specified in sysentvec.
         * Otherwise any address above .data section can be selected.
         * Same logic is used for stack address randomization.
         * If the address randomization is applied map a guard page
         * at the top of UVA.
         */
        vm_object_reference(obj);
        if ((imgp->imgp_flags & IMGP_ASLR_SHARED_PAGE) != 0) {
                sharedpage_addr = round_page((vm_offset_t)p->p_vmspace->vm_daddr +
                    lim_max(curthread, RLIMIT_DATA));

                error = vm_map_fixed(map, NULL, 0,
                    sv->sv_maxuser - PAGE_SIZE, PAGE_SIZE,
                    VM_PROT_NONE, VM_PROT_NONE, MAP_CREATE_GUARD);
                if (error != KERN_SUCCESS) {
                        /*
                         * This is not fatal, so let's just print a warning
                         * and continue.
                         */
                        uprintf("%s: Mapping guard page at the top of UVA failed"
                            " mach error %d errno %d",
                            __func__, error, vm_mmap_to_errno(error));
                }

                error = vm_map_find(map, obj, 0,
                    &sharedpage_addr, sv->sv_shared_page_len,
                    sv->sv_maxuser, VMFS_ANY_SPACE,
                    VM_PROT_READ | VM_PROT_EXECUTE,
                    VM_PROT_READ | VM_PROT_EXECUTE,
                    MAP_INHERIT_SHARE | MAP_ACC_NO_CHARGE);
        } else {
                sharedpage_addr = sv->sv_shared_page_base;
                error = vm_map_fixed(map, obj, 0,
                    sharedpage_addr, sv->sv_shared_page_len,
                    VM_PROT_READ | VM_PROT_EXECUTE,
                    VM_PROT_READ | VM_PROT_EXECUTE,
                    MAP_INHERIT_SHARE | MAP_ACC_NO_CHARGE);
        }
        if (error != KERN_SUCCESS) {
                uprintf("%s: mapping shared page at addr: %p"
                    "failed, mach error %d errno %d\n", __func__,
                    (void *)sharedpage_addr, error, vm_mmap_to_errno(error));
                vm_object_deallocate(obj);
                return (vm_mmap_to_errno(error));
        }
out:
        /*
         * vm_ssize and vm_maxsaddr are somewhat antiquated concepts, but they
         * are still used to enforce the stack rlimit on the process stack.
         */
        vmspace->vm_maxsaddr = (char *)stack_addr;
        vmspace->vm_stacktop = stack_top;
        vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT;
        vmspace->vm_shp_base = sharedpage_addr;

        return (0);
}

/*
 * Copy out argument and environment strings from the old process address
 * space into the temporary string buffer.
 */
int
exec_copyin_args(struct image_args *args, const char *fname,
    char **argv, char **envv)
{
        u_long arg, env;
        int error;

        bzero(args, sizeof(*args));
        if (argv == NULL)
                return (EFAULT);

        /*
         * Allocate demand-paged memory for the file name, argument, and
         * environment strings.
         */
        error = exec_alloc_args(args);
        if (error != 0)
                return (error);

        /*
         * Copy the file name.
         */
        error = exec_args_add_fname(args, fname, UIO_USERSPACE);
        if (error != 0)
                goto err_exit;

        /*
         * extract arguments first
         */
        for (;;) {
                error = fueword(argv++, &arg);
                if (error == -1) {
                        error = EFAULT;
                        goto err_exit;
                }
                if (arg == 0)
                        break;
                error = exec_args_add_arg(args, (char *)(uintptr_t)arg,
                    UIO_USERSPACE);
                if (error != 0)
                        goto err_exit;
        }

        /*
         * extract environment strings
         */
        if (envv) {
                for (;;) {
                        error = fueword(envv++, &env);
                        if (error == -1) {
                                error = EFAULT;
                                goto err_exit;
                        }
                        if (env == 0)
                                break;
                        error = exec_args_add_env(args,
                            (char *)(uintptr_t)env, UIO_USERSPACE);
                        if (error != 0)
                                goto err_exit;
                }
        }

        return (0);

err_exit:
        exec_free_args(args);
        return (error);
}

struct exec_args_kva {
        vm_offset_t addr;
        u_int gen;
        SLIST_ENTRY(exec_args_kva) next;
};

DPCPU_DEFINE_STATIC(struct exec_args_kva *, exec_args_kva);

static SLIST_HEAD(, exec_args_kva) exec_args_kva_freelist;
static struct mtx exec_args_kva_mtx;
static u_int exec_args_gen;

static void
exec_prealloc_args_kva(void *arg __unused)
{
        struct exec_args_kva *argkva;
        u_int i;

        SLIST_INIT(&exec_args_kva_freelist);
        mtx_init(&exec_args_kva_mtx, "exec args kva", NULL, MTX_DEF);
        for (i = 0; i < exec_map_entries; i++) {
                argkva = malloc(sizeof(*argkva), M_PARGS, M_WAITOK);
                argkva->addr = kmap_alloc_wait(exec_map, exec_map_entry_size);
                argkva->gen = exec_args_gen;
                SLIST_INSERT_HEAD(&exec_args_kva_freelist, argkva, next);
        }
}
SYSINIT(exec_args_kva, SI_SUB_EXEC, SI_ORDER_ANY, exec_prealloc_args_kva, NULL);

static vm_offset_t
exec_alloc_args_kva(void **cookie)
{
        struct exec_args_kva *argkva;

        argkva = (void *)atomic_readandclear_ptr(
            (uintptr_t *)DPCPU_PTR(exec_args_kva));
        if (argkva == NULL) {
                mtx_lock(&exec_args_kva_mtx);
                while ((argkva = SLIST_FIRST(&exec_args_kva_freelist)) == NULL)
                        (void)mtx_sleep(&exec_args_kva_freelist,
                            &exec_args_kva_mtx, 0, "execkva", 0);
                SLIST_REMOVE_HEAD(&exec_args_kva_freelist, next);
                mtx_unlock(&exec_args_kva_mtx);
        }
        kasan_mark((void *)argkva->addr, exec_map_entry_size,
            exec_map_entry_size, 0);
        *(struct exec_args_kva **)cookie = argkva;
        return (argkva->addr);
}

static void
exec_release_args_kva(struct exec_args_kva *argkva, u_int gen)
{
        vm_offset_t base;

        base = argkva->addr;
        kasan_mark((void *)argkva->addr, 0, exec_map_entry_size,
            KASAN_EXEC_ARGS_FREED);
        if (argkva->gen != gen) {
                (void)vm_map_madvise(exec_map, base, base + exec_map_entry_size,
                    MADV_FREE);
                argkva->gen = gen;
        }
        if (!atomic_cmpset_ptr((uintptr_t *)DPCPU_PTR(exec_args_kva),
            (uintptr_t)NULL, (uintptr_t)argkva)) {
                mtx_lock(&exec_args_kva_mtx);
                SLIST_INSERT_HEAD(&exec_args_kva_freelist, argkva, next);
                wakeup_one(&exec_args_kva_freelist);
                mtx_unlock(&exec_args_kva_mtx);
        }
}

static void
exec_free_args_kva(void *cookie)
{

        exec_release_args_kva(cookie, exec_args_gen);
}

static void
exec_args_kva_lowmem(void *arg __unused, int flags __unused)
{
        SLIST_HEAD(, exec_args_kva) head;
        struct exec_args_kva *argkva;
        u_int gen;
        int i;

        gen = atomic_fetchadd_int(&exec_args_gen, 1) + 1;

        /*
         * Force an madvise of each KVA range. Any currently allocated ranges
         * will have MADV_FREE applied once they are freed.
         */
        SLIST_INIT(&head);
        mtx_lock(&exec_args_kva_mtx);
        SLIST_SWAP(&head, &exec_args_kva_freelist, exec_args_kva);
        mtx_unlock(&exec_args_kva_mtx);
        while ((argkva = SLIST_FIRST(&head)) != NULL) {
                SLIST_REMOVE_HEAD(&head, next);
                exec_release_args_kva(argkva, gen);
        }

        CPU_FOREACH(i) {
                argkva = (void *)atomic_readandclear_ptr(
                    (uintptr_t *)DPCPU_ID_PTR(i, exec_args_kva));
                if (argkva != NULL)
                        exec_release_args_kva(argkva, gen);
        }
}
EVENTHANDLER_DEFINE(vm_lowmem, exec_args_kva_lowmem, NULL,
    EVENTHANDLER_PRI_ANY);

/*
 * Allocate temporary demand-paged, zero-filled memory for the file name,
 * argument, and environment strings.
 */
int
exec_alloc_args(struct image_args *args)
{

        args->buf = (char *)exec_alloc_args_kva(&args->bufkva);
        return (0);
}

void
exec_free_args(struct image_args *args)
{

        if (args->buf != NULL) {
                exec_free_args_kva(args->bufkva);
                args->buf = NULL;
        }
        if (args->fname_buf != NULL) {
                free(args->fname_buf, M_TEMP);
                args->fname_buf = NULL;
        }
}

/*
 * A set to functions to fill struct image args.
 *
 * NOTE: exec_args_add_fname() must be called (possibly with a NULL
 * fname) before the other functions.  All exec_args_add_arg() calls must
 * be made before any exec_args_add_env() calls.  exec_args_adjust_args()
 * may be called any time after exec_args_add_fname().
 *
 * exec_args_add_fname() - install path to be executed
 * exec_args_add_arg() - append an argument string
 * exec_args_add_env() - append an env string
 * exec_args_adjust_args() - adjust location of the argument list to
 *                           allow new arguments to be prepended
 */
int
exec_args_add_fname(struct image_args *args, const char *fname,
    enum uio_seg segflg)
{
        int error;
        size_t length;

        KASSERT(args->fname == NULL, ("fname already appended"));
        KASSERT(args->endp == NULL, ("already appending to args"));

        if (fname != NULL) {
                args->fname = args->buf;
                error = segflg == UIO_SYSSPACE ?
                    copystr(fname, args->fname, PATH_MAX, &length) :
                    copyinstr(fname, args->fname, PATH_MAX, &length);
                if (error != 0)
                        return (error == ENAMETOOLONG ? E2BIG : error);
        } else
                length = 0;

        /* Set up for _arg_*()/_env_*() */
        args->endp = args->buf + length;
        /* begin_argv must be set and kept updated */
        args->begin_argv = args->endp;
        KASSERT(exec_map_entry_size - length >= ARG_MAX,
            ("too little space remaining for arguments %zu < %zu",
            exec_map_entry_size - length, (size_t)ARG_MAX));
        args->stringspace = ARG_MAX;

        return (0);
}

static int
exec_args_add_str(struct image_args *args, const char *str,
    enum uio_seg segflg, int *countp)
{
        int error;
        size_t length;

        KASSERT(args->endp != NULL, ("endp not initialized"));
        KASSERT(args->begin_argv != NULL, ("begin_argp not initialized"));

        error = (segflg == UIO_SYSSPACE) ?
            copystr(str, args->endp, args->stringspace, &length) :
            copyinstr(str, args->endp, args->stringspace, &length);
        if (error != 0)
                return (error == ENAMETOOLONG ? E2BIG : error);
        args->stringspace -= length;
        args->endp += length;
        (*countp)++;

        return (0);
}

int
exec_args_add_arg(struct image_args *args, const char *argp,
    enum uio_seg segflg)
{

        KASSERT(args->envc == 0, ("appending args after env"));

        return (exec_args_add_str(args, argp, segflg, &args->argc));
}

int
exec_args_add_env(struct image_args *args, const char *envp,
    enum uio_seg segflg)
{

        if (args->envc == 0)
                args->begin_envv = args->endp;

        return (exec_args_add_str(args, envp, segflg, &args->envc));
}

int
exec_args_adjust_args(struct image_args *args, size_t consume, ssize_t extend)
{
        ssize_t offset;

        KASSERT(args->endp != NULL, ("endp not initialized"));
        KASSERT(args->begin_argv != NULL, ("begin_argp not initialized"));

        offset = extend - consume;
        if (args->stringspace < offset)
                return (E2BIG);
        memmove(args->begin_argv + extend, args->begin_argv + consume,
            args->endp - args->begin_argv + consume);
        if (args->envc > 0)
                args->begin_envv += offset;
        args->endp += offset;
        args->stringspace -= offset;
        return (0);
}

char *
exec_args_get_begin_envv(struct image_args *args)
{

        KASSERT(args->endp != NULL, ("endp not initialized"));

        if (args->envc > 0)
                return (args->begin_envv);
        return (args->endp);
}

/*
 * Copy strings out to the new process address space, constructing new arg
 * and env vector tables. Return a pointer to the base so that it can be used
 * as the initial stack pointer.
 */
int
exec_copyout_strings(struct image_params *imgp, uintptr_t *stack_base)
{
        int argc, envc;
        char **vectp;
        char *stringp;
        uintptr_t destp, ustringp;
        struct ps_strings *arginfo;
        struct proc *p;
        struct sysentvec *sysent;
        size_t execpath_len;
        int error, szsigcode;
        char canary[sizeof(long) * 8];

        p = imgp->proc;
        sysent = p->p_sysent;

        destp = PROC_PS_STRINGS(p);
        arginfo = imgp->ps_strings = (void *)destp;

        /*
         * Install sigcode.
         */
        if (sysent->sv_shared_page_base == 0 && sysent->sv_szsigcode != NULL) {
                szsigcode = *(sysent->sv_szsigcode);
                destp -= szsigcode;
                destp = rounddown2(destp, sizeof(void *));
                error = copyout(sysent->sv_sigcode, (void *)destp, szsigcode);
                if (error != 0)
                        return (error);
        }

        /*
         * Copy the image path for the rtld.
         */
        if (imgp->execpath != NULL && imgp->auxargs != NULL) {
                execpath_len = strlen(imgp->execpath) + 1;
                destp -= execpath_len;
                destp = rounddown2(destp, sizeof(void *));
                imgp->execpathp = (void *)destp;
                error = copyout(imgp->execpath, imgp->execpathp, execpath_len);
                if (error != 0)
                        return (error);
        }

        /*
         * Prepare the canary for SSP.
         */
        arc4rand(canary, sizeof(canary), 0);
        destp -= sizeof(canary);
        imgp->canary = (void *)destp;
        error = copyout(canary, imgp->canary, sizeof(canary));
        if (error != 0)
                return (error);
        imgp->canarylen = sizeof(canary);

        /*
         * Prepare the pagesizes array.
         */
        imgp->pagesizeslen = sizeof(pagesizes[0]) * MAXPAGESIZES;
        destp -= imgp->pagesizeslen;
        destp = rounddown2(destp, sizeof(void *));
        imgp->pagesizes = (void *)destp;
        error = copyout(pagesizes, imgp->pagesizes, imgp->pagesizeslen);
        if (error != 0)
                return (error);

        /*
         * Allocate room for the argument and environment strings.
         */
        destp -= ARG_MAX - imgp->args->stringspace;
        destp = rounddown2(destp, sizeof(void *));
        ustringp = destp;

        if (imgp->auxargs) {
                /*
                 * Allocate room on the stack for the ELF auxargs
                 * array.  It has up to AT_COUNT entries.
                 */
                destp -= AT_COUNT * sizeof(Elf_Auxinfo);
                destp = rounddown2(destp, sizeof(void *));
        }

        vectp = (char **)destp;

        /*
         * Allocate room for the argv[] and env vectors including the
         * terminating NULL pointers.
         */
        vectp -= imgp->args->argc + 1 + imgp->args->envc + 1;

        /*
         * vectp also becomes our initial stack base
         */
        *stack_base = (uintptr_t)vectp;

        stringp = imgp->args->begin_argv;
        argc = imgp->args->argc;
        envc = imgp->args->envc;

        /*
         * Copy out strings - arguments and environment.
         */
        error = copyout(stringp, (void *)ustringp,
            ARG_MAX - imgp->args->stringspace);
        if (error != 0)
                return (error);

        /*
         * Fill in "ps_strings" struct for ps, w, etc.
         */
        imgp->argv = vectp;
        if (suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp) != 0 ||
            suword32(&arginfo->ps_nargvstr, argc) != 0)
                return (EFAULT);

        /*
         * Fill in argument portion of vector table.
         */
        for (; argc > 0; --argc) {
                if (suword(vectp++, ustringp) != 0)
                        return (EFAULT);
                while (*stringp++ != 0)
                        ustringp++;
                ustringp++;
        }

        /* a null vector table pointer separates the argp's from the envp's */
        if (suword(vectp++, 0) != 0)
                return (EFAULT);

        imgp->envv = vectp;
        if (suword(&arginfo->ps_envstr, (long)(intptr_t)vectp) != 0 ||
            suword32(&arginfo->ps_nenvstr, envc) != 0)
                return (EFAULT);

        /*
         * Fill in environment portion of vector table.
         */
        for (; envc > 0; --envc) {
                if (suword(vectp++, ustringp) != 0)
                        return (EFAULT);
                while (*stringp++ != 0)
                        ustringp++;
                ustringp++;
        }

        /* end of vector table is a null pointer */
        if (suword(vectp, 0) != 0)
                return (EFAULT);

        if (imgp->auxargs) {
                vectp++;
                error = imgp->sysent->sv_copyout_auxargs(imgp,
                    (uintptr_t)vectp);
                if (error != 0)
                        return (error);
        }

        return (0);
}

/*
 * Check permissions of file to execute.
 *      Called with imgp->vp locked.
 *      Return 0 for success or error code on failure.
 */
int
exec_check_permissions(struct image_params *imgp)
{
        struct vnode *vp = imgp->vp;
        struct vattr *attr = imgp->attr;
        struct thread *td;
        int error;

        td = curthread;

        /* Get file attributes */
        error = VOP_GETATTR(vp, attr, td->td_ucred);
        if (error)
                return (error);

#ifdef MAC
        error = mac_vnode_check_exec(td->td_ucred, imgp->vp, imgp);
        if (error)
                return (error);
#endif

        /*
         * 1) Check if file execution is disabled for the filesystem that
         *    this file resides on.
         * 2) Ensure that at least one execute bit is on. Otherwise, a
         *    privileged user will always succeed, and we don't want this
         *    to happen unless the file really is executable.
         * 3) Ensure that the file is a regular file.
         */
        if ((vp->v_mount->mnt_flag & MNT_NOEXEC) ||
            (attr->va_mode & (S_IXUSR | S_IXGRP | S_IXOTH)) == 0 ||
            (attr->va_type != VREG))
                return (EACCES);

        /*
         * Zero length files can't be exec'd
         */
        if (attr->va_size == 0)
                return (ENOEXEC);

        /*
         *  Check for execute permission to file based on current credentials.
         */
        error = VOP_ACCESS(vp, VEXEC, td->td_ucred, td);
        if (error)
                return (error);

        /*
         * Check number of open-for-writes on the file and deny execution
         * if there are any.
         *
         * Add a text reference now so no one can write to the
         * executable while we're activating it.
         *
         * Remember if this was set before and unset it in case this is not
         * actually an executable image.
         */
        error = VOP_SET_TEXT(vp);
        if (error != 0)
                return (error);
        imgp->textset = true;

        /*
         * Call filesystem specific open routine (which does nothing in the
         * general case).
         */
        error = VOP_OPEN(vp, FREAD, td->td_ucred, td, NULL);
        if (error == 0)
                imgp->opened = true;
        return (error);
}

/*
 * Exec handler registration
 */
int
exec_register(const struct execsw *execsw_arg)
{
        const struct execsw **es, **xs, **newexecsw;
        u_int count = 2;        /* New slot and trailing NULL */

        if (execsw)
                for (es = execsw; *es; es++)
                        count++;
        newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK);
        xs = newexecsw;
        if (execsw)
                for (es = execsw; *es; es++)
                        *xs++ = *es;
        *xs++ = execsw_arg;
        *xs = NULL;
        if (execsw)
                free(execsw, M_TEMP);
        execsw = newexecsw;
        return (0);
}

int
exec_unregister(const struct execsw *execsw_arg)
{
        const struct execsw **es, **xs, **newexecsw;
        int count = 1;

        if (execsw == NULL)
                panic("unregister with no handlers left?\n");

        for (es = execsw; *es; es++) {
                if (*es == execsw_arg)
                        break;
        }
        if (*es == NULL)
                return (ENOENT);
        for (es = execsw; *es; es++)
                if (*es != execsw_arg)
                        count++;
        newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK);
        xs = newexecsw;
        for (es = execsw; *es; es++)
                if (*es != execsw_arg)
                        *xs++ = *es;
        *xs = NULL;
        if (execsw)
                free(execsw, M_TEMP);
        execsw = newexecsw;
        return (0);
}

/*
 * Write out a core segment to the compression stream.
 */
static int
compress_chunk(struct coredump_params *cp, char *base, char *buf, size_t len)
{
        size_t chunk_len;
        int error;

        error = 0;
        while (len > 0) {
                chunk_len = MIN(len, CORE_BUF_SIZE);

                /*
                 * We can get EFAULT error here.
                 * In that case zero out the current chunk of the segment.
                 */
                error = copyin(base, buf, chunk_len);
                if (error != 0)
                        bzero(buf, chunk_len);
                error = compressor_write(cp->comp, buf, chunk_len);
                if (error != 0)
                        break;
                base += chunk_len;
                len -= chunk_len;
        }
        return (error);
}

int
core_write(struct coredump_params *cp, const void *base, size_t len,
    off_t offset, enum uio_seg seg, size_t *resid)
{
        return ((*cp->cdw->write_fn)(cp->cdw, base, len, offset, seg,
            cp->active_cred, resid, cp->td));
}

static int
core_extend(struct coredump_params *cp, off_t newsz)
{
        return ((*cp->cdw->extend_fn)(cp->cdw, newsz, cp->active_cred));
}

int
core_output(char *base, size_t len, off_t offset, struct coredump_params *cp,
    void *tmpbuf)
{
        vm_map_t map;
        size_t resid, runlen;
        int error;
        bool success;

        KASSERT((uintptr_t)base % PAGE_SIZE == 0,
            ("%s: user address %p is not page-aligned", __func__, base));

        if (cp->comp != NULL)
                return (compress_chunk(cp, base, tmpbuf, len));

        error = 0;
        map = &cp->td->td_proc->p_vmspace->vm_map;
        for (; len > 0; base += runlen, offset += runlen, len -= runlen) {
                /*
                 * Attempt to page in all virtual pages in the range.  If a
                 * virtual page is not backed by the pager, it is represented as
                 * a hole in the file.  This can occur with zero-filled
                 * anonymous memory or truncated files, for example.
                 */
                for (runlen = 0; runlen < len; runlen += PAGE_SIZE) {
                        if (core_dump_can_intr && curproc_sigkilled())
                                return (EINTR);
                        error = vm_fault(map, (uintptr_t)base + runlen,
                            VM_PROT_READ, VM_FAULT_NOFILL, NULL);
                        if (runlen == 0)
                                success = error == KERN_SUCCESS;
                        else if ((error == KERN_SUCCESS) != success)
                                break;
                }

                if (success) {
                        error = core_write(cp, base, runlen, offset,
                            UIO_USERSPACE, &resid);
                        if (error != 0) {
                                if (error != EFAULT)
                                        break;

                                /*
                                 * EFAULT may be returned if the user mapping
                                 * could not be accessed, e.g., because a mapped
                                 * file has been truncated.  Skip the page if no
                                 * progress was made, to protect against a
                                 * hypothetical scenario where vm_fault() was
                                 * successful but core_write() returns EFAULT
                                 * anyway.
                                 */
                                runlen -= resid;
                                if (runlen == 0) {
                                        success = false;
                                        runlen = PAGE_SIZE;
                                }
                        }
                }
                if (!success) {
                        error = core_extend(cp, offset + runlen);
                        if (error != 0)
                                break;
                }
        }
        return (error);
}

/*
 * Drain into a core file.
 */
int
sbuf_drain_core_output(void *arg, const char *data, int len)
{
        struct coredump_params *cp;
        struct proc *p;
        int error, locked;

        cp = arg;
        p = cp->td->td_proc;

        /*
         * Some kern_proc out routines that print to this sbuf may
         * call us with the process lock held. Draining with the
         * non-sleepable lock held is unsafe. The lock is needed for
         * those routines when dumping a live process. In our case we
         * can safely release the lock before draining and acquire
         * again after.
         */
        locked = PROC_LOCKED(p);
        if (locked)
                PROC_UNLOCK(p);
        if (cp->comp != NULL)
                error = compressor_write(cp->comp, __DECONST(char *, data),
                    len);
        else
                error = core_write(cp, __DECONST(void *, data), len, cp->offset,
                    UIO_SYSSPACE, NULL);
        if (locked)
                PROC_LOCK(p);
        if (error != 0)
                return (-error);
        cp->offset += len;
        return (len);
}