sys_process.c

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/*-
 * Copyright (c) 1994, Sean Eric Fagan
 * 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 Sean Eric Fagan.
 * 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 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>
__FBSDID("$BSDSUniX$");

#include "opt_compat.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/syscallsubr.h>
#include <sys/sysent.h>
#include <sys/sysproto.h>
#include <sys/priv.h>
#include <sys/proc.h>
#include <sys/procctl.h>
#include <sys/vnode.h>
#include <sys/ptrace.h>
#include <sys/sx.h>
#include <sys/malloc.h>
#include <sys/signalvar.h>

#include <machine/reg.h>

#include <security/audit/audit.h>

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

#ifdef COMPAT_32BIT
#include <sys/procfs.h>
#include <compat/compat32bit/compat32bit_signal.h>

struct ptrace_io_desc32 {
        int             piod_op;
        uint32_t        piod_offs;
        uint32_t        piod_addr;
        uint32_t        piod_len;
};

struct ptrace_vm_entry32 {
        int             pve_entry;
        int             pve_timestamp;
        uint32_t        pve_start;
        uint32_t        pve_end;
        uint32_t        pve_offset;
        u_int           pve_prot;
        u_int           pve_pathlen;
        int32_t         pve_fileid;
        u_int           pve_fsid;
        uint32_t        pve_path;
};

struct ptrace_lwpinfo32 {
        lwpid_t pl_lwpid;       /* LWP described. */
        int     pl_event;       /* Event that stopped the LWP. */
        int     pl_flags;       /* LWP flags. */
        sigset_t        pl_sigmask;     /* LWP signal mask */
        sigset_t        pl_siglist;     /* LWP pending signal */
        struct siginfo32 pl_siginfo;    /* siginfo for signal */
        char    pl_tdname[MAXCOMLEN + 1];       /* LWP name. */
        pid_t   pl_child_pid;           /* New child pid */
        u_int           pl_syscall_code;
        u_int           pl_syscall_narg;
};

#endif

/*
 * Functions implemented using PROC_ACTION():
 *
 * proc_read_regs(proc, regs)
 *      Get the current user-visible register set from the process
 *      and copy it into the regs structure (<machine/reg.h>).
 *      The process is stopped at the time read_regs is called.
 *
 * proc_write_regs(proc, regs)
 *      Update the current register set from the passed in regs
 *      structure.  Take care to avoid clobbering special CPU
 *      registers or privileged bits in the PSL.
 *      Depending on the architecture this may have fix-up work to do,
 *      especially if the IAR or PCW are modified.
 *      The process is stopped at the time write_regs is called.
 *
 * proc_read_fpregs, proc_write_fpregs
 *      deal with the floating point register set, otherwise as above.
 *
 * proc_read_dbregs, proc_write_dbregs
 *      deal with the processor debug register set, otherwise as above.
 *
 * proc_sstep(proc)
 *      Arrange for the process to trap after executing a single instruction.
 */

#define PROC_ACTION(action) do {                                        \
        int error;                                                      \
                                                                        \
        PROC_LOCK_ASSERT(td->td_proc, MA_OWNED);                        \
        if ((td->td_proc->p_flag & P_INMEM) == 0)                       \
                error = EIO;                                            \
        else                                                            \
                error = (action);                                       \
        return (error);                                                 \
} while(0)

int
proc_read_regs(struct thread *td, struct reg *regs)
{

        PROC_ACTION(fill_regs(td, regs));
}

int
proc_write_regs(struct thread *td, struct reg *regs)
{

        PROC_ACTION(set_regs(td, regs));
}

int
proc_read_dbregs(struct thread *td, struct dbreg *dbregs)
{

        PROC_ACTION(fill_dbregs(td, dbregs));
}

int
proc_write_dbregs(struct thread *td, struct dbreg *dbregs)
{

        PROC_ACTION(set_dbregs(td, dbregs));
}

/*
 * Ptrace doesn't support fpregs at all, and there are no security holes
 * or translations for fpregs, so we can just copy them.
 */
int
proc_read_fpregs(struct thread *td, struct fpreg *fpregs)
{

        PROC_ACTION(fill_fpregs(td, fpregs));
}

int
proc_write_fpregs(struct thread *td, struct fpreg *fpregs)
{

        PROC_ACTION(set_fpregs(td, fpregs));
}

#ifdef COMPAT_32BIT
/* For 32 bit binaries, we need to expose the 32 bit regs layouts. */
int
proc_read_regs32(struct thread *td, struct reg32 *regs32)
{

        PROC_ACTION(fill_regs32(td, regs32));
}

int
proc_write_regs32(struct thread *td, struct reg32 *regs32)
{

        PROC_ACTION(set_regs32(td, regs32));
}

int
proc_read_dbregs32(struct thread *td, struct dbreg32 *dbregs32)
{

        PROC_ACTION(fill_dbregs32(td, dbregs32));
}

int
proc_write_dbregs32(struct thread *td, struct dbreg32 *dbregs32)
{

        PROC_ACTION(set_dbregs32(td, dbregs32));
}

int
proc_read_fpregs32(struct thread *td, struct fpreg32 *fpregs32)
{

        PROC_ACTION(fill_fpregs32(td, fpregs32));
}

int
proc_write_fpregs32(struct thread *td, struct fpreg32 *fpregs32)
{

        PROC_ACTION(set_fpregs32(td, fpregs32));
}
#endif

int
proc_sstep(struct thread *td)
{

        PROC_ACTION(ptrace_single_step(td));
}

int
proc_rwmem(struct proc *p, struct uio *uio)
{
        vm_map_t map;
        vm_offset_t pageno;             /* page number */
        vm_prot_t reqprot;
        int error, fault_flags, page_offset, writing;

        /*
         * Assert that someone has locked this vmspace.  (Should be
         * curthread but we can't assert that.)  This keeps the process
         * from exiting out from under us until this operation completes.
         */
        KASSERT(p->p_lock >= 1, ("%s: process %p (pid %d) not held", __func__,
            p, p->p_pid));

        /*
         * The map we want...
         */
        map = &p->p_vmspace->vm_map;

        /*
         * If we are writing, then we request vm_fault() to create a private
         * copy of each page.  Since these copies will not be writeable by the
         * process, we must explicity request that they be dirtied.
         */
        writing = uio->uio_rw == UIO_WRITE;
        reqprot = writing ? VM_PROT_COPY | VM_PROT_READ : VM_PROT_READ;
        fault_flags = writing ? VM_FAULT_DIRTY : VM_FAULT_NORMAL;

        /*
         * Only map in one page at a time.  We don't have to, but it
         * makes things easier.  This way is trivial - right?
         */
        do {
                vm_offset_t uva;
                u_int len;
                vm_page_t m;

                uva = (vm_offset_t)uio->uio_offset;

                /*
                 * Get the page number of this segment.
                 */
                pageno = trunc_page(uva);
                page_offset = uva - pageno;

                /*
                 * How many bytes to copy
                 */
                len = min(PAGE_SIZE - page_offset, uio->uio_resid);

                /*
                 * Fault and hold the page on behalf of the process.
                 */
                error = vm_fault_hold(map, pageno, reqprot, fault_flags, &m);
                if (error != KERN_SUCCESS) {
                        if (error == KERN_RESOURCE_SHORTAGE)
                                error = ENOMEM;
                        else
                                error = EFAULT;
                        break;
                }

                /*
                 * Now do the i/o move.
                 */
                error = uiomove_fromphys(&m, page_offset, len, uio);

                /* Make the I-cache coherent for breakpoints. */
                if (writing && error == 0) {
                        vm_map_lock_read(map);
                        if (vm_map_check_protection(map, pageno, pageno +
                            PAGE_SIZE, VM_PROT_EXECUTE))
                                vm_sync_icache(map, uva, len);
                        vm_map_unlock_read(map);
                }

                /*
                 * Release the page.
                 */
                vm_page_lock(m);
                vm_page_unhold(m);
                vm_page_unlock(m);

        } while (error == 0 && uio->uio_resid > 0);

        return (error);
}

static int
ptrace_vm_entry(struct thread *td, struct proc *p, struct ptrace_vm_entry *pve)
{
        struct vattr vattr;
        vm_map_t map;
        vm_map_entry_t entry;
        vm_object_t obj, tobj, lobj;
        struct vmspace *vm;
        struct vnode *vp;
        char *freepath, *fullpath;
        u_int pathlen;
        int error, index, vfslocked;

        error = 0;
        obj = NULL;

        vm = vmspace_acquire_ref(p);
        map = &vm->vm_map;
        vm_map_lock_read(map);

        do {
                entry = map->header.next;
                index = 0;
                while (index < pve->pve_entry && entry != &map->header) {
                        entry = entry->next;
                        index++;
                }
                if (index != pve->pve_entry) {
                        error = EINVAL;
                        break;
                }
                while (entry != &map->header &&
                    (entry->eflags & MAP_ENTRY_IS_SUB_MAP) != 0) {
                        entry = entry->next;
                        index++;
                }
                if (entry == &map->header) {
                        error = ENOENT;
                        break;
                }

                /* We got an entry. */
                pve->pve_entry = index + 1;
                pve->pve_timestamp = map->timestamp;
                pve->pve_start = entry->start;
                pve->pve_end = entry->end - 1;
                pve->pve_offset = entry->offset;
                pve->pve_prot = entry->protection;

                /* Backing object's path needed? */
                if (pve->pve_pathlen == 0)
                        break;

                pathlen = pve->pve_pathlen;
                pve->pve_pathlen = 0;

                obj = entry->object.vm_object;
                if (obj != NULL)
                        VM_OBJECT_LOCK(obj);
        } while (0);

        vm_map_unlock_read(map);
        vmspace_free(vm);

        pve->pve_fsid = VNOVAL;
        pve->pve_fileid = VNOVAL;

        if (error == 0 && obj != NULL) {
                lobj = obj;
                for (tobj = obj; tobj != NULL; tobj = tobj->backing_object) {
                        if (tobj != obj)
                                VM_OBJECT_LOCK(tobj);
                        if (lobj != obj)
                                VM_OBJECT_UNLOCK(lobj);
                        lobj = tobj;
                        pve->pve_offset += tobj->backing_object_offset;
                }
                vp = (lobj->type == OBJT_VNODE) ? lobj->handle : NULL;
                if (vp != NULL)
                        vref(vp);
                if (lobj != obj)
                        VM_OBJECT_UNLOCK(lobj);
                VM_OBJECT_UNLOCK(obj);

                if (vp != NULL) {
                        freepath = NULL;
                        fullpath = NULL;
                        vn_fullpath(td, vp, &fullpath, &freepath);
                        vfslocked = VFS_LOCK_GIANT(vp->v_mount);
                        vn_lock(vp, LK_SHARED | LK_RETRY);
                        if (VOP_GETATTR(vp, &vattr, td->td_ucred) == 0) {
                                pve->pve_fileid = vattr.va_fileid;
                                pve->pve_fsid = vattr.va_fsid;
                        }
                        vput(vp);
                        VFS_UNLOCK_GIANT(vfslocked);

                        if (fullpath != NULL) {
                                pve->pve_pathlen = strlen(fullpath) + 1;
                                if (pve->pve_pathlen <= pathlen) {
                                        error = copyout(fullpath, pve->pve_path,
                                            pve->pve_pathlen);
                                } else
                                        error = ENAMETOOLONG;
                        }
                        if (freepath != NULL)
                                free(freepath, M_TEMP);
                }
        }
        if (error == 0)
                CTR3(KTR_PTRACE, "PT_VM_ENTRY: pid %d, entry %d, start %p",
                    p->p_pid, pve->pve_entry, pve->pve_start);

        return (error);
}

#ifdef COMPAT_32BIT
static int      
ptrace_vm_entry32(struct thread *td, struct proc *p,
    struct ptrace_vm_entry32 *pve32)
{
        struct ptrace_vm_entry pve;
        int error;

        pve.pve_entry = pve32->pve_entry;
        pve.pve_pathlen = pve32->pve_pathlen;
        pve.pve_path = (void *)(uintptr_t)pve32->pve_path;

        error = ptrace_vm_entry(td, p, &pve);
        if (error == 0) {
                pve32->pve_entry = pve.pve_entry;
                pve32->pve_timestamp = pve.pve_timestamp;
                pve32->pve_start = pve.pve_start;
                pve32->pve_end = pve.pve_end;
                pve32->pve_offset = pve.pve_offset;
                pve32->pve_prot = pve.pve_prot;
                pve32->pve_fileid = pve.pve_fileid;
                pve32->pve_fsid = pve.pve_fsid;
        }

        pve32->pve_pathlen = pve.pve_pathlen;
        return (error);
}

static void
ptrace_lwpinfo_to32(const struct ptrace_lwpinfo *pl,
    struct ptrace_lwpinfo32 *pl32)
{

        pl32->pl_lwpid = pl->pl_lwpid;
        pl32->pl_event = pl->pl_event;
        pl32->pl_flags = pl->pl_flags;
        pl32->pl_sigmask = pl->pl_sigmask;
        pl32->pl_siglist = pl->pl_siglist;
        siginfo_to_siginfo32(&pl->pl_siginfo, &pl32->pl_siginfo);
        strcpy(pl32->pl_tdname, pl->pl_tdname);
        pl32->pl_child_pid = pl->pl_child_pid;
        pl32->pl_syscall_code = pl->pl_syscall_code;
        pl32->pl_syscall_narg = pl->pl_syscall_narg;
}
#endif /* COMPAT_32BIT */

/*
 * Process debugging system call.
 */
#ifndef _SYS_SYSPROTO_H_
struct ptrace_args {
        int     req;
        pid_t   pid;
        caddr_t addr;
        int     data;
};
#endif

#ifdef COMPAT_32BIT
/*
 * This CPP subterfuge is to try and reduce the number of ifdefs in
 * the body of the code.
 *   COPYIN(uap->addr, &r.reg, sizeof r.reg);
 * becomes either:
 *   copyin(uap->addr, &r.reg, sizeof r.reg);
 * or
 *   copyin(uap->addr, &r.reg32, sizeof r.reg32);
 * .. except this is done at runtime.
 */
#define COPYIN(u, k, s)         wrap32 ? \
        copyin(u, k ## 32, s ## 32) : \
        copyin(u, k, s)
#define COPYOUT(k, u, s)        wrap32 ? \
        copyout(k ## 32, u, s ## 32) : \
        copyout(k, u, s)
#else
#define COPYIN(u, k, s)         copyin(u, k, s)
#define COPYOUT(k, u, s)        copyout(k, u, s)
#endif
int
sys_ptrace(struct thread *td, struct ptrace_args *uap)
{
        /*
         * XXX this obfuscation is to reduce stack usage, but the register
         * structs may be too large to put on the stack anyway.
         */
        union {
                struct ptrace_io_desc piod;
                struct ptrace_lwpinfo pl;
                struct ptrace_vm_entry pve;
                struct dbreg dbreg;
                struct fpreg fpreg;
                struct reg reg;
#ifdef COMPAT_32BIT
                struct dbreg32 dbreg32;
                struct fpreg32 fpreg32;
                struct reg32 reg32;
                struct ptrace_io_desc32 piod32;
                struct ptrace_lwpinfo32 pl32;
                struct ptrace_vm_entry32 pve32;
#endif
        } r;
        void *addr;
        int error = 0;
#ifdef COMPAT_32BIT
        int wrap32 = 0;

        if (SV_CURPROC_FLAG(SV_ILP32))
                wrap32 = 1;
#endif
        AUDIT_ARG_PID(uap->pid);
        AUDIT_ARG_CMD(uap->req);
        AUDIT_ARG_VALUE(uap->data);
        addr = &r;
        switch (uap->req) {
        case PT_GETREGS:
        case PT_GETFPREGS:
        case PT_GETDBREGS:
        case PT_LWPINFO:
                break;
        case PT_SETREGS:
                error = COPYIN(uap->addr, &r.reg, sizeof r.reg);
                break;
        case PT_SETFPREGS:
                error = COPYIN(uap->addr, &r.fpreg, sizeof r.fpreg);
                break;
        case PT_SETDBREGS:
                error = COPYIN(uap->addr, &r.dbreg, sizeof r.dbreg);
                break;
        case PT_IO:
                error = COPYIN(uap->addr, &r.piod, sizeof r.piod);
                break;
        case PT_VM_ENTRY:
                error = COPYIN(uap->addr, &r.pve, sizeof r.pve);
                break;
        default:
                addr = uap->addr;
                break;
        }
        if (error)
                return (error);

        error = kern_ptrace(td, uap->req, uap->pid, addr, uap->data);
        if (error)
                return (error);

        switch (uap->req) {
        case PT_VM_ENTRY:
                error = COPYOUT(&r.pve, uap->addr, sizeof r.pve);
                break;
        case PT_IO:
                error = COPYOUT(&r.piod, uap->addr, sizeof r.piod);
                break;
        case PT_GETREGS:
                error = COPYOUT(&r.reg, uap->addr, sizeof r.reg);
                break;
        case PT_GETFPREGS:
                error = COPYOUT(&r.fpreg, uap->addr, sizeof r.fpreg);
                break;
        case PT_GETDBREGS:
                error = COPYOUT(&r.dbreg, uap->addr, sizeof r.dbreg);
                break;
        case PT_LWPINFO:
                error = copyout(&r.pl, uap->addr, uap->data);
                break;
        }

        return (error);
}
#undef COPYIN
#undef COPYOUT

#ifdef COMPAT_32BIT
/*
 *   PROC_READ(regs, td2, addr);
 * becomes either:
 *   proc_read_regs(td2, addr);
 * or
 *   proc_read_regs32(td2, addr);
 * .. except this is done at runtime.  There is an additional
 * complication in that PROC_WRITE disallows 32 bit consumers
 * from writing to 64 bit address space targets.
 */
#define PROC_READ(w, t, a)      wrap32 ? \
        proc_read_ ## w ## 32(t, a) : \
        proc_read_ ## w (t, a)
#define PROC_WRITE(w, t, a)     wrap32 ? \
        (safe ? proc_write_ ## w ## 32(t, a) : EINVAL ) : \
        proc_write_ ## w (t, a)
#else
#define PROC_READ(w, t, a)      proc_read_ ## w (t, a)
#define PROC_WRITE(w, t, a)     proc_write_ ## w (t, a)
#endif

int
kern_ptrace(struct thread *td, int req, pid_t pid, void *addr, int data)
{
        struct iovec iov;
        struct uio uio;
        struct proc *curp, *p, *pp;
        struct thread *td2 = NULL;
        struct ptrace_io_desc *piod = NULL;
        struct ptrace_lwpinfo *pl;
        int error, write, tmp, num;
        int proctree_locked = 0;
        lwpid_t tid = 0, *buf;
#ifdef COMPAT_32BIT
        int wrap32 = 0, safe = 0;
        struct ptrace_io_desc32 *piod32 = NULL;
        struct ptrace_lwpinfo32 *pl32 = NULL;
        struct ptrace_lwpinfo plr;
#endif

        curp = td->td_proc;

        /* Lock proctree before locking the process. */
        switch (req) {
        case PT_TRACE_ME:
        case PT_ATTACH:
        case PT_STEP:
        case PT_CONTINUE:
        case PT_TO_SCE:
        case PT_TO_SCX:
        case PT_SYSCALL:
        case PT_FOLLOW_FORK:
        case PT_DETACH:
                sx_xlock(&proctree_lock);
                proctree_locked = 1;
                break;
        default:
                break;
        }

        write = 0;
        if (req == PT_TRACE_ME) {
                p = td->td_proc;
                PROC_LOCK(p);
        } else {
                if (pid <= PID_MAX) {
                        if ((p = pfind(pid)) == NULL) {
                                if (proctree_locked)
                                        sx_xunlock(&proctree_lock);
                                return (ESRCH);
                        }
                } else {
                        td2 = tdfind(pid, -1);
                        if (td2 == NULL) {
                                if (proctree_locked)
                                        sx_xunlock(&proctree_lock);
                                return (ESRCH);
                        }
                        p = td2->td_proc;
                        tid = pid;
                        pid = p->p_pid;
                }
        }
        AUDIT_ARG_PROCESS(p);

        if ((p->p_flag & P_WEXIT) != 0) {
                error = ESRCH;
                goto fail;
        }
        if ((error = p_cansee(td, p)) != 0)
                goto fail;

        if ((error = p_candebug(td, p)) != 0)
                goto fail;

        /*
         * System processes can't be debugged.
         */
        if ((p->p_flag & P_SYSTEM) != 0) {
                error = EINVAL;
                goto fail;
        }

        if (tid == 0) {
                if ((p->p_flag & P_STOPPED_TRACE) != 0) {
                        KASSERT(p->p_xthread != NULL, ("NULL p_xthread"));
                        td2 = p->p_xthread;
                } else {
                        td2 = FIRST_THREAD_IN_PROC(p);
                }
                tid = td2->td_tid;
        }

#ifdef COMPAT_32BIT
        /*
         * Test if we're a 32 bit client and what the target is.
         * Set the wrap controls accordingly.
         */
        if (SV_CURPROC_FLAG(SV_ILP32)) {
                if (SV_PROC_FLAG(td2->td_proc, SV_ILP32))
                        safe = 1;
                wrap32 = 1;
        }
#endif
        /*
         * Permissions check
         */
        switch (req) {
        case PT_TRACE_ME:
                /* Always legal. */
                break;

        case PT_ATTACH:
                /* Self */
                if (p->p_pid == td->td_proc->p_pid) {
                        error = EINVAL;
                        goto fail;
                }

                /* Already traced */
                if (p->p_flag & P_TRACED) {
                        error = EBUSY;
                        goto fail;
                }

                /* Can't trace an ancestor if you're being traced. */
                if (curp->p_flag & P_TRACED) {
                        for (pp = curp->p_pptr; pp != NULL; pp = pp->p_pptr) {
                                if (pp == p) {
                                        error = EINVAL;
                                        goto fail;
                                }
                        }
                }


                /* OK */
                break;

        case PT_CLEARSTEP:
                /* Allow thread to clear single step for itself */
                if (td->td_tid == tid)
                        break;

                /* FALLTHROUGH */
        default:
                /* not being traced... */
                if ((p->p_flag & P_TRACED) == 0) {
                        error = EPERM;
                        goto fail;
                }

                /* not being traced by YOU */
                if (p->p_pptr != td->td_proc) {
                        error = EBUSY;
                        goto fail;
                }

                /* not currently stopped */
                if ((p->p_flag & (P_STOPPED_SIG | P_STOPPED_TRACE)) == 0 ||
                    p->p_suspcount != p->p_numthreads  ||
                    (p->p_flag & P_WAITED) == 0) {
                        error = EBUSY;
                        goto fail;
                }

                if ((p->p_flag & P_STOPPED_TRACE) == 0) {
                        static int count = 0;
                        if (count++ == 0)
                                printf("P_STOPPED_TRACE not set.\n");
                }

                /* OK */
                break;
        }

        /* Keep this process around until we finish this request. */
        _PHOLD(p);

#ifdef FIX_SSTEP
        /*
         * Single step fixup ala procfs
         */
        FIX_SSTEP(td2);
#endif

        /*
         * Actually do the requests
         */

        td->td_retval[0] = 0;

        switch (req) {
        case PT_TRACE_ME:
                /* set my trace flag and "owner" so it can read/write me */
                p->p_flag |= P_TRACED;
                if (p->p_flag & P_PPWAIT)
                        p->p_flag |= P_PPTRACE;
                p->p_oppid = p->p_pptr->p_pid;
                CTR1(KTR_PTRACE, "PT_TRACE_ME: pid %d", p->p_pid);
                break;

        case PT_ATTACH:
                /* security check done above */
                /*
                 * It would be nice if the tracing relationship was separate
                 * from the parent relationship but that would require
                 * another set of links in the proc struct or for "wait"
                 * to scan the entire proc table.  To make life easier,
                 * we just re-parent the process we're trying to trace.
                 * The old parent is remembered so we can put things back
                 * on a "detach".
                 */
                p->p_flag |= P_TRACED;
                p->p_oppid = p->p_pptr->p_pid;
                if (p->p_pptr != td->td_proc) {
                        proc_reparent(p, td->td_proc);
                }
                data = SIGSTOP;
                CTR2(KTR_PTRACE, "PT_ATTACH: pid %d, oppid %d", p->p_pid,
                    p->p_oppid);
                goto sendsig;   /* in PT_CONTINUE below */

        case PT_CLEARSTEP:
                CTR2(KTR_PTRACE, "PT_CLEARSTEP: tid %d (pid %d)", td2->td_tid,
                    p->p_pid);
                error = ptrace_clear_single_step(td2);
                break;

        case PT_SETSTEP:
                CTR2(KTR_PTRACE, "PT_SETSTEP: tid %d (pid %d)", td2->td_tid,
                    p->p_pid);
                error = ptrace_single_step(td2);
                break;

        case PT_SUSPEND:
                CTR2(KTR_PTRACE, "PT_SUSPEND: tid %d (pid %d)", td2->td_tid,
                    p->p_pid);
                td2->td_dbgflags |= TDB_SUSPEND;
                thread_lock(td2);
                td2->td_flags |= TDF_NEEDSUSPCHK;
                thread_unlock(td2);
                break;

        case PT_RESUME:
                CTR2(KTR_PTRACE, "PT_RESUME: tid %d (pid %d)", td2->td_tid,
                    p->p_pid);
                td2->td_dbgflags &= ~TDB_SUSPEND;
                break;

        case PT_FOLLOW_FORK:
                CTR3(KTR_PTRACE, "PT_FOLLOW_FORK: pid %d %s -> %s", p->p_pid,
                    p->p_flag & P_FOLLOWFORK ? "enabled" : "disabled",
                    data ? "enabled" : "disabled");
                if (data)
                        p->p_flag |= P_FOLLOWFORK;
                else
                        p->p_flag &= ~P_FOLLOWFORK;
                break;

        case PT_STEP:
        case PT_CONTINUE:
        case PT_TO_SCE:
        case PT_TO_SCX:
        case PT_SYSCALL:
        case PT_DETACH:
                /* Zero means do not send any signal */
                if (data < 0 || data > _SIG_MAXSIG) {
                        error = EINVAL;
                        break;
                }

                switch (req) {
                case PT_STEP:
                        CTR2(KTR_PTRACE, "PT_STEP: tid %d (pid %d)",
                            td2->td_tid, p->p_pid);
                        error = ptrace_single_step(td2);
                        if (error)
                                goto out;
                        break;
                case PT_CONTINUE:
                case PT_TO_SCE:
                case PT_TO_SCX:
                case PT_SYSCALL:
                        if (addr != (void *)1) {
                                error = ptrace_set_pc(td2,
                                    (u_long)(uintfptr_t)addr);
                                if (error)
                                        goto out;
                        }
                        switch (req) {
                        case PT_TO_SCE:
                                p->p_stops |= S_PT_SCE;
                                CTR4(KTR_PTRACE,
                    "PT_TO_SCE: pid %d, stops = %#x, PC = %#lx, sig = %d",
                                    p->p_pid, p->p_stops,
                                    (u_long)(uintfptr_t)addr, data);
                                break;
                        case PT_TO_SCX:
                                p->p_stops |= S_PT_SCX;
                                CTR4(KTR_PTRACE,
                    "PT_TO_SCX: pid %d, stops = %#x, PC = %#lx, sig = %d",
                                    p->p_pid, p->p_stops,
                                    (u_long)(uintfptr_t)addr, data);
                                break;
                        case PT_SYSCALL:
                                p->p_stops |= S_PT_SCE | S_PT_SCX;
                                CTR4(KTR_PTRACE,
                    "PT_SYSCALL: pid %d, stops = %#x, PC = %#lx, sig = %d",
                                    p->p_pid, p->p_stops,
                                    (u_long)(uintfptr_t)addr, data);
                                break;
                        case PT_CONTINUE:
                                CTR3(KTR_PTRACE,
                                    "PT_CONTINUE: pid %d, PC = %#lx, sig = %d",
                                    p->p_pid, (u_long)(uintfptr_t)addr, data);
                                break;
                        }
                        break;
                case PT_DETACH:
                        /*
                         * Reset the process parent.
                         *
                         * NB: This clears P_TRACED before reparenting
                         * a detached process back to its original
                         * parent.  Otherwise the debugee will be set
                         * as an orphan of the debugger.
                         */
                        p->p_flag &= ~(P_TRACED | P_WAITED | P_FOLLOWFORK);
                        if (p->p_oppid != p->p_pptr->p_pid) {
                                PROC_LOCK(p->p_pptr);
                                sigqueue_take(p->p_ksi);
                                PROC_UNLOCK(p->p_pptr);

                                pp = proc_realparent(p);
                                proc_reparent(p, pp);
                                if (pp == initproc)
                                        p->p_sigparent = SIGCHLD;
                                CTR3(KTR_PTRACE,
                            "PT_DETACH: pid %d reparented to pid %d, sig %d",
                                    p->p_pid, pp->p_pid, data);
                        } else
                                CTR2(KTR_PTRACE, "PT_DETACH: pid %d, sig %d",
                                    p->p_pid, data);
                        p->p_oppid = 0;

                        /* should we send SIGCHLD? */
                        /* childproc_continued(p); */
                        break;
                }

        sendsig:
                if (proctree_locked) {
                        sx_xunlock(&proctree_lock);
                        proctree_locked = 0;
                }
                p->p_xstat = data;
                p->p_xthread = NULL;
                if ((p->p_flag & (P_STOPPED_SIG | P_STOPPED_TRACE)) != 0) {
                        /* deliver or queue signal */
                        td2->td_dbgflags &= ~TDB_XSIG;
                        td2->td_xsig = data;

                        if (req == PT_DETACH) {
                                struct thread *td3;
                                FOREACH_THREAD_IN_PROC(p, td3) {
                                        td3->td_dbgflags &= ~TDB_SUSPEND; 
                                }
                        }
                        /*
                         * unsuspend all threads, to not let a thread run,
                         * you should use PT_SUSPEND to suspend it before
                         * continuing process.
                         */
                        PROC_SLOCK(p);
                        p->p_flag &= ~(P_STOPPED_TRACE|P_STOPPED_SIG|P_WAITED);
                        thread_unsuspend(p);
                        PROC_SUNLOCK(p);
                } else {
                        if (data)
                                kern_psignal(p, data);
                }
                break;

        case PT_WRITE_I:
        case PT_WRITE_D:
                td2->td_dbgflags |= TDB_USERWR;
                write = 1;
                /* FALLTHROUGH */
        case PT_READ_I:
        case PT_READ_D:
                PROC_UNLOCK(p);
                tmp = 0;
                /* write = 0 set above */
                iov.iov_base = write ? (caddr_t)&data : (caddr_t)&tmp;
                iov.iov_len = sizeof(int);
                uio.uio_iov = &iov;
                uio.uio_iovcnt = 1;
                uio.uio_offset = (off_t)(uintptr_t)addr;
                uio.uio_resid = sizeof(int);
                uio.uio_segflg = UIO_SYSSPACE;  /* i.e.: the uap */
                uio.uio_rw = write ? UIO_WRITE : UIO_READ;
                uio.uio_td = td;
                error = proc_rwmem(p, &uio);
                if (uio.uio_resid != 0) {
                        /*
                         * XXX proc_rwmem() doesn't currently return ENOSPC,
                         * so I think write() can bogusly return 0.
                         * XXX what happens for short writes?  We don't want
                         * to write partial data.
                         * XXX proc_rwmem() returns EPERM for other invalid
                         * addresses.  Convert this to EINVAL.  Does this
                         * clobber returns of EPERM for other reasons?
                         */
                        if (error == 0 || error == ENOSPC || error == EPERM)
                                error = EINVAL; /* EOF */
                }
                if (!write)
                        td->td_retval[0] = tmp;
                if (error == 0) {
                        if (write)
                                CTR3(KTR_PTRACE, "PT_WRITE: pid %d: %p <= %#x",
                                    p->p_pid, addr, data);
                        else
                                CTR3(KTR_PTRACE, "PT_READ: pid %d: %p >= %#x",
                                    p->p_pid, addr, tmp);
                }
                PROC_LOCK(p);
                break;

        case PT_IO:
#ifdef COMPAT_32BIT
                if (wrap32) {
                        piod32 = addr;
                        iov.iov_base = (void *)(uintptr_t)piod32->piod_addr;
                        iov.iov_len = piod32->piod_len;
                        uio.uio_offset = (off_t)(uintptr_t)piod32->piod_offs;
                        uio.uio_resid = piod32->piod_len;
                } else
#endif
                {
                        piod = addr;
                        iov.iov_base = piod->piod_addr;
                        iov.iov_len = piod->piod_len;
                        uio.uio_offset = (off_t)(uintptr_t)piod->piod_offs;
                        uio.uio_resid = piod->piod_len;
                }
                uio.uio_iov = &iov;
                uio.uio_iovcnt = 1;
                uio.uio_segflg = UIO_USERSPACE;
                uio.uio_td = td;
#ifdef COMPAT_32BIT
                tmp = wrap32 ? piod32->piod_op : piod->piod_op;
#else
                tmp = piod->piod_op;
#endif
                switch (tmp) {
                case PIOD_READ_D:
                case PIOD_READ_I:
                        CTR3(KTR_PTRACE, "PT_IO: pid %d: READ (%p, %#x)",
                            p->p_pid, (uintptr_t)uio.uio_offset, uio.uio_resid);
                        uio.uio_rw = UIO_READ;
                        break;
                case PIOD_WRITE_D:
                case PIOD_WRITE_I:
                        CTR3(KTR_PTRACE, "PT_IO: pid %d: WRITE (%p, %#x)",
                            p->p_pid, (uintptr_t)uio.uio_offset, uio.uio_resid);
                        td2->td_dbgflags |= TDB_USERWR;
                        uio.uio_rw = UIO_WRITE;
                        break;
                default:
                        error = EINVAL;
                        goto out;
                }
                PROC_UNLOCK(p);
                error = proc_rwmem(p, &uio);
#ifdef COMPAT_32BIT
                if (wrap32)
                        piod32->piod_len -= uio.uio_resid;
                else
#endif
                        piod->piod_len -= uio.uio_resid;
                PROC_LOCK(p);
                break;

        case PT_KILL:
                CTR1(KTR_PTRACE, "PT_KILL: pid %d", p->p_pid);
                data = SIGKILL;
                goto sendsig;   /* in PT_CONTINUE above */

        case PT_SETREGS:
                CTR2(KTR_PTRACE, "PT_SETREGS: tid %d (pid %d)", td2->td_tid,
                    p->p_pid);
                td2->td_dbgflags |= TDB_USERWR;
                error = PROC_WRITE(regs, td2, addr);
                break;

        case PT_GETREGS:
                CTR2(KTR_PTRACE, "PT_GETREGS: tid %d (pid %d)", td2->td_tid,
                    p->p_pid);
                error = PROC_READ(regs, td2, addr);
                break;

        case PT_SETFPREGS:
                CTR2(KTR_PTRACE, "PT_SETFPREGS: tid %d (pid %d)", td2->td_tid,
                    p->p_pid);
                td2->td_dbgflags |= TDB_USERWR;
                error = PROC_WRITE(fpregs, td2, addr);
                break;

        case PT_GETFPREGS:
                CTR2(KTR_PTRACE, "PT_GETFPREGS: tid %d (pid %d)", td2->td_tid,
                    p->p_pid);
                error = PROC_READ(fpregs, td2, addr);
                break;

        case PT_SETDBREGS:
                CTR2(KTR_PTRACE, "PT_SETDBREGS: tid %d (pid %d)", td2->td_tid,
                    p->p_pid);
                td2->td_dbgflags |= TDB_USERWR;
                error = PROC_WRITE(dbregs, td2, addr);
                break;

        case PT_GETDBREGS:
                CTR2(KTR_PTRACE, "PT_GETDBREGS: tid %d (pid %d)", td2->td_tid,
                    p->p_pid);
                error = PROC_READ(dbregs, td2, addr);
                break;

        case PT_LWPINFO:
                if (data <= 0 ||
#ifdef COMPAT_32BIT
                    (!wrap32 && data > sizeof(*pl)) ||
                    (wrap32 && data > sizeof(*pl32))) {
#else
                    data > sizeof(*pl)) {
#endif
                        error = EINVAL;
                        break;
                }
#ifdef COMPAT_32BIT
                if (wrap32) {
                        pl = &plr;
                        pl32 = addr;
                } else
#endif
                pl = addr;
                pl->pl_lwpid = td2->td_tid;
                pl->pl_event = PL_EVENT_NONE;
                pl->pl_flags = 0;
                if (td2->td_dbgflags & TDB_XSIG) {
                        pl->pl_event = PL_EVENT_SIGNAL;
                        if (td2->td_dbgksi.ksi_signo != 0 &&
#ifdef COMPAT_32BIT
                            ((!wrap32 && data >= offsetof(struct ptrace_lwpinfo,
                            pl_siginfo) + sizeof(pl->pl_siginfo)) ||
                            (wrap32 && data >= offsetof(struct ptrace_lwpinfo32,
                            pl_siginfo) + sizeof(struct siginfo32)))
#else
                            data >= offsetof(struct ptrace_lwpinfo, pl_siginfo)
                            + sizeof(pl->pl_siginfo)
#endif
                        ){
                                pl->pl_flags |= PL_FLAG_SI;
                                pl->pl_siginfo = td2->td_dbgksi.ksi_info;
                        }
                }
                if ((pl->pl_flags & PL_FLAG_SI) == 0)
                        bzero(&pl->pl_siginfo, sizeof(pl->pl_siginfo));
                if (td2->td_dbgflags & TDB_SCE)
                        pl->pl_flags |= PL_FLAG_SCE;
                else if (td2->td_dbgflags & TDB_SCX)
                        pl->pl_flags |= PL_FLAG_SCX;
                if (td2->td_dbgflags & TDB_EXEC)
                        pl->pl_flags |= PL_FLAG_EXEC;
                if (td2->td_dbgflags & TDB_FORK) {
                        pl->pl_flags |= PL_FLAG_FORKED;
                        pl->pl_child_pid = td2->td_dbg_forked;
                }
                if (td2->td_dbgflags & TDB_CHILD)
                        pl->pl_flags |= PL_FLAG_CHILD;
                pl->pl_sigmask = td2->td_sigmask;
                pl->pl_siglist = td2->td_siglist;
                strcpy(pl->pl_tdname, td2->td_name);
                if ((td2->td_dbgflags & (TDB_SCE | TDB_SCX)) != 0) {
                        pl->pl_syscall_code = td2->td_dbg_sc_code;
                        pl->pl_syscall_narg = td2->td_dbg_sc_narg;
                } else {
                        pl->pl_syscall_code = 0;
                        pl->pl_syscall_narg = 0;
                }
#ifdef COMPAT_32BIT
                if (wrap32)
                        ptrace_lwpinfo_to32(pl, pl32);
#endif
                CTR6(KTR_PTRACE,
    "PT_LWPINFO: tid %d (pid %d) event %d flags %#x child pid %d syscall %d",
                    td2->td_tid, p->p_pid, pl->pl_event, pl->pl_flags,
                    pl->pl_child_pid, pl->pl_syscall_code);
                break;

        case PT_GETNUMLWPS:
                CTR2(KTR_PTRACE, "PT_GETNUMLWPS: pid %d: %d threads", p->p_pid,
                    p->p_numthreads);
                td->td_retval[0] = p->p_numthreads;
                break;

        case PT_GETLWPLIST:
                CTR3(KTR_PTRACE, "PT_GETLWPLIST: pid %d: data %d, actual %d",
                    p->p_pid, data, p->p_numthreads);
                if (data <= 0) {
                        error = EINVAL;
                        break;
                }
                num = imin(p->p_numthreads, data);
                PROC_UNLOCK(p);
                buf = malloc(num * sizeof(lwpid_t), M_TEMP, M_WAITOK);
                tmp = 0;
                PROC_LOCK(p);
                FOREACH_THREAD_IN_PROC(p, td2) {
                        if (tmp >= num)
                                break;
                        buf[tmp++] = td2->td_tid;
                }
                PROC_UNLOCK(p);
                error = copyout(buf, addr, tmp * sizeof(lwpid_t));
                free(buf, M_TEMP);
                if (!error)
                        td->td_retval[0] = tmp;
                PROC_LOCK(p);
                break;

        case PT_VM_TIMESTAMP:
                CTR2(KTR_PTRACE, "PT_VM_TIMESTAMP: pid %d: timestamp %d",
                    p->p_pid, p->p_vmspace->vm_map.timestamp);
                td->td_retval[0] = p->p_vmspace->vm_map.timestamp;
                break;

        case PT_VM_ENTRY:
                PROC_UNLOCK(p);
#ifdef COMPAT_32BIT
                if (wrap32)
                        error = ptrace_vm_entry32(td, p, addr);
                else
#endif
                error = ptrace_vm_entry(td, p, addr);
                PROC_LOCK(p);
                break;

        default:
#ifdef __HAVE_PTRACE_MACHDEP
                if (req >= PT_FIRSTMACH) {
                        PROC_UNLOCK(p);
                        error = cpu_ptrace(td2, req, addr, data);
                        PROC_LOCK(p);
                } else
#endif
                        /* Unknown request. */
                        error = EINVAL;
                break;
        }

out:
        /* Drop our hold on this process now that the request has completed. */
        _PRELE(p);
fail:
        PROC_UNLOCK(p);
        if (proctree_locked)
                sx_xunlock(&proctree_lock);
        return (error);
}
#undef PROC_READ
#undef PROC_WRITE

/*
 * Stop a process because of a debugging event;
 * stay stopped until p->p_step is cleared
 * (cleared by PIOCCONT in procfs).
 */
void
stopevent(struct proc *p, unsigned int event, unsigned int val)
{

        PROC_LOCK_ASSERT(p, MA_OWNED);
        p->p_step = 1;
        CTR3(KTR_PTRACE, "stopevent: pid %d event %u val %u", p->p_pid, event,
            val);
        do {
                p->p_xstat = val;
                p->p_xthread = NULL;
                p->p_stype = event;     /* Which event caused the stop? */
                wakeup(&p->p_stype);    /* Wake up any PIOCWAIT'ing procs */
                msleep(&p->p_step, &p->p_mtx, PWAIT, "stopevent", 0);
        } while (p->p_step);
}

static int
protect_setchild(struct thread *td, struct proc *p, int flags)
{

        PROC_LOCK_ASSERT(p, MA_OWNED);
        if (p->p_flag & P_SYSTEM || p_cansched(td, p) != 0)
                return (0);
        if (flags & PPROT_SET) {
                p->p_flag |= P_PROTECTED;
                if (flags & PPROT_INHERIT)
                        p->p_flag2 |= P2_INHERIT_PROTECTED;
        } else {
                p->p_flag &= ~P_PROTECTED;
                p->p_flag2 &= ~P2_INHERIT_PROTECTED;
        }
        return (1);
}

static int
protect_setchildren(struct thread *td, struct proc *top, int flags)
{
        struct proc *p;
        int ret;

        p = top;
        ret = 0;
        sx_assert(&proctree_lock, SX_LOCKED);
        for (;;) {
                ret |= protect_setchild(td, p, flags);
                PROC_UNLOCK(p);
                /*
                 * If this process has children, descend to them next,
                 * otherwise do any siblings, and if done with this level,
                 * follow back up the tree (but not past top).
                 */
                if (!LIST_EMPTY(&p->p_children))
                        p = LIST_FIRST(&p->p_children);
                else for (;;) {
                        if (p == top) {
                                PROC_LOCK(p);
                                return (ret);
                        }
                        if (LIST_NEXT(p, p_sibling)) {
                                p = LIST_NEXT(p, p_sibling);
                                break;
                        }
                        p = p->p_pptr;
                }
                PROC_LOCK(p);
        }
}

static int
protect_set(struct thread *td, struct proc *p, int flags)
{
        int error, ret;

        switch (PPROT_OP(flags)) {
        case PPROT_SET:
        case PPROT_CLEAR:
                break;
        default:
                return (EINVAL);
        }

        if ((PPROT_FLAGS(flags) & ~(PPROT_DESCEND | PPROT_INHERIT)) != 0)
                return (EINVAL);

        error = priv_check(td, PRIV_VM_MADV_PROTECT);
        if (error)
                return (error);

        if (flags & PPROT_DESCEND)
                ret = protect_setchildren(td, p, flags);
        else
                ret = protect_setchild(td, p, flags);
        if (ret == 0)
                return (EPERM);
        return (0);
}

#ifndef _SYS_SYSPROTO_H_
struct procctl_args {
        idtype_t idtype;
        id_t    id;
        int     com;
        void    *data;
};
#endif
/* ARGSUSED */
int
sys_procctl(struct thread *td, struct procctl_args *uap)
{
        int error, flags;
        void *data;

        switch (uap->com) {
        case PROC_SPROTECT:
                error = copyin(uap->data, &flags, sizeof(flags));
                if (error)
                        return (error);
                data = &flags;
                break;
        default:
                return (EINVAL);
        }

        return (kern_procctl(td, uap->idtype, uap->id, uap->com, data));
}

static int
kern_procctl_single(struct thread *td, struct proc *p, int com, void *data)
{

        PROC_LOCK_ASSERT(p, MA_OWNED);
        switch (com) {
        case PROC_SPROTECT:
                return (protect_set(td, p, *(int *)data));
        default:
                return (EINVAL);
        }
}

int
kern_procctl(struct thread *td, idtype_t idtype, id_t id, int com, void *data)
{
        struct pgrp *pg;
        struct proc *p;
        int error, first_error, ok;

        sx_slock(&proctree_lock);
        switch (idtype) {
        case P_PID:
                p = pfind(id);
                if (p == NULL) {
                        error = ESRCH;
                        break;
                }
                if (p->p_state == PRS_NEW)
                        error = ESRCH;
                else
                        error = p_cansee(td, p);
                if (error == 0)
                        error = kern_procctl_single(td, p, com, data);
                PROC_UNLOCK(p);
                break;
        case P_PGID:
                /*
                 * Attempt to apply the operation to all members of the
                 * group.  Ignore processes in the group that can't be
                 * seen.  Ignore errors so long as at least one process is
                 * able to complete the request successfully.
                 */
                pg = pgfind(id);
                if (pg == NULL) {
                        error = ESRCH;
                        break;
                }
                PGRP_UNLOCK(pg);
                ok = 0;
                first_error = 0;
                LIST_FOREACH(p, &pg->pg_members, p_pglist) {
                        PROC_LOCK(p);
                        if (p->p_state == PRS_NEW || p_cansee(td, p) != 0) {
                                PROC_UNLOCK(p);
                                continue;
                        }
                        error = kern_procctl_single(td, p, com, data);
                        PROC_UNLOCK(p);
                        if (error == 0)
                                ok = 1;
                        else if (first_error == 0)
                                first_error = error;
                }
                if (ok)
                        error = 0;
                else if (first_error != 0)
                        error = first_error;
                else
                        /*
                         * Was not able to see any processes in the
                         * process group.
                         */
                        error = ESRCH;
                break;
        default:
                error = EINVAL;
                break;
        }
        sx_sunlock(&proctree_lock);
        return (error);
}