/*
 * 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.
 *
 * $FreeBSD: src/sys/kern/sys_process.c,v 1.51.2.6 2003/01/08 03:06:45 kan Exp $
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/sysmsg.h>
#include <sys/uio.h>
#include <sys/proc.h>
#include <sys/caps.h>
#include <sys/vnode.h>
#include <sys/ptrace.h>
#include <sys/reg.h>
#include <sys/lock.h>

#include <vm/vm.h>
#include <vm/pmap.h>
#include <vm/vm_map.h>
#include <vm/vm_page.h>

#include <vfs/procfs/procfs.h>

#include <sys/thread2.h>
#include <sys/spinlock2.h>


/*
 * Process debugging system call.
 *
 * MPALMOSTSAFE
 */
int
sys_ptrace(struct sysmsg *sysmsg, const struct ptrace_args *uap)
{
        struct proc *p = curproc;

        /*
         * 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 dbreg dbreg;
                struct fpreg fpreg;
                struct reg reg;
        } r;
        void *addr;
        int error = 0;

        addr = &r;
        switch (uap->req) {
        case PT_GETREGS:
        case PT_GETFPREGS:
#ifdef PT_GETDBREGS
        case PT_GETDBREGS:
#endif
                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;
#ifdef PT_SETDBREGS
        case PT_SETDBREGS:
                error = copyin(uap->addr, &r.dbreg, sizeof r.dbreg);
                break;
#endif
        case PT_IO:
                error = copyin(uap->addr, &r.piod, sizeof r.piod);
                break;
        default:
                addr = uap->addr;
        }
        if (error)
                return (error);

        error = kern_ptrace(p, uap->req, uap->pid, addr, uap->data,
                        &sysmsg->sysmsg_result);
        if (error)
                return (error);

        switch (uap->req) {
        case PT_IO:
                (void)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;
#ifdef PT_GETDBREGS
        case PT_GETDBREGS:
                error = copyout(&r.dbreg, uap->addr, sizeof r.dbreg);
                break;
#endif
        }

        return (error);
}

int
kern_ptrace(struct proc *curp, int req, pid_t pid, void *addr,
            int data, int *res)
{
        struct proc *p, *pp;
        struct lwp *lp;
        struct iovec iov;
        struct uio uio;
        struct ptrace_io_desc *piod;
        int error = 0;
        int write, tmp;
        int t;

        write = 0;
        if (req == PT_TRACE_ME) {
                p = curp;
                PHOLD(p);
        } else {
                if ((p = pfind(pid)) == NULL)
                        return ESRCH;
        }
        if (!PRISON_CHECK(curp->p_ucred, p->p_ucred)) {
                PRELE(p);
                return (ESRCH);
        }
        if (p->p_flags & P_SYSTEM) {
                PRELE(p);
                return EINVAL;
        }

        lwkt_gettoken(&p->p_token);
        /* Can't trace a process that's currently exec'ing. */
        if ((p->p_flags & P_INEXEC) != 0) {
                lwkt_reltoken(&p->p_token);
                PRELE(p);
                return EAGAIN;
        }

        /*
         * Permissions check
         */
        switch (req) {
        case PT_TRACE_ME:
                /* Always legal. */
                break;

        case PT_ATTACH:
                /* Self */
                if (p->p_pid == curp->p_pid) {
                        lwkt_reltoken(&p->p_token);
                        PRELE(p);
                        return EINVAL;
                }

                /* Already traced */
                if (p->p_flags & P_TRACED) {
                        lwkt_reltoken(&p->p_token);
                        PRELE(p);
                        return EBUSY;
                }

                if (curp->p_flags & P_TRACED)
                        for (pp = curp->p_pptr; pp != NULL; pp = pp->p_pptr)
                                if (pp == p) {
                                        lwkt_reltoken(&p->p_token);
                                        PRELE(p);
                                        return (EINVAL);
                                }

                /* not owned by you, has done setuid (unless you're root) */
                if ((p->p_ucred->cr_ruid != curp->p_ucred->cr_ruid) ||
                     (p->p_flags & P_SUGID)) {
                        error = caps_priv_check(curp->p_ucred,
                                                SYSCAP_RESTRICTEDROOT);
                        if (error) {
                                lwkt_reltoken(&p->p_token);
                                PRELE(p);
                                return error;
                        }
                }

                /* can't trace init when securelevel > 0 */
                if (securelevel > 0 && p->p_pid == 1) {
                        lwkt_reltoken(&p->p_token);
                        PRELE(p);
                        return EPERM;
                }

                /* OK */
                break;

        case PT_READ_I:
        case PT_READ_D:
        case PT_WRITE_I:
        case PT_WRITE_D:
        case PT_IO:
        case PT_CONTINUE:
        case PT_KILL:
        case PT_STEP:
        case PT_DETACH:
#ifdef PT_GETREGS
        case PT_GETREGS:
#endif
#ifdef PT_SETREGS
        case PT_SETREGS:
#endif
#ifdef PT_GETFPREGS
        case PT_GETFPREGS:
#endif
#ifdef PT_SETFPREGS
        case PT_SETFPREGS:
#endif
#ifdef PT_GETDBREGS
        case PT_GETDBREGS:
#endif
#ifdef PT_SETDBREGS
        case PT_SETDBREGS:
#endif
                /* not being traced... */
                if ((p->p_flags & P_TRACED) == 0) {
                        lwkt_reltoken(&p->p_token);
                        PRELE(p);
                        return EPERM;
                }

                /* not being traced by YOU */
                if (p->p_pptr != curp) {
                        lwkt_reltoken(&p->p_token);
                        PRELE(p);
                        return EBUSY;
                }

                /* not currently stopped */
                if (p->p_stat != SSTOP ||
                    (p->p_flags & P_WAITED) == 0) {
                        lwkt_reltoken(&p->p_token);
                        PRELE(p);
                        return EBUSY;
                }

                /* OK */
                break;

        default:
                lwkt_reltoken(&p->p_token);
                PRELE(p);
                return EINVAL;
        }

        /* XXX lwp */
        lp = FIRST_LWP_IN_PROC(p);
        if (lp == NULL) {
                lwkt_reltoken(&p->p_token);
                PRELE(p);
                return EINVAL;
        }

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

        /*
         * Actually do the requests
         */

        *res = 0;

        switch (req) {
        case PT_TRACE_ME:
                /* set my trace flag and "owner" so it can read/write me */
                p->p_flags |= P_TRACED;
                p->p_oppid = p->p_pptr->p_pid;
                lwkt_reltoken(&p->p_token);
                PRELE(p);
                return 0;

        case PT_ATTACH:
                /* security check done above */
                p->p_flags |= P_TRACED;
                p->p_oppid = p->p_pptr->p_pid;
                proc_reparent(p, curp);
                data = SIGSTOP;
                goto sendsig;   /* in PT_CONTINUE below */

        case PT_STEP:
        case PT_CONTINUE:
        case PT_DETACH:
                /* Zero means do not send any signal */
                if (data < 0 || data >= _SIG_MAXSIG) {
                        lwkt_reltoken(&p->p_token);
                        PRELE(p);
                        return EINVAL;
                }

                LWPHOLD(lp);

                if (req == PT_STEP) {
                        if ((error = ptrace_single_step (lp))) {
                                LWPRELE(lp);
                                lwkt_reltoken(&p->p_token);
                                PRELE(p);
                                return error;
                        }
                }

                if (addr != (void *)1) {
                        if ((error = ptrace_set_pc (lp, (u_long)addr))) {
                                LWPRELE(lp);
                                lwkt_reltoken(&p->p_token);
                                PRELE(p);
                                return error;
                        }
                }
                LWPRELE(lp);

                if (req == PT_DETACH) {
                        /* reset process parent */
                        if (p->p_oppid != p->p_pptr->p_pid) {
                                struct proc *pp;

                                pp = pfind(p->p_oppid);
                                if (pp) {
                                        proc_reparent(p, pp);
                                        PRELE(pp);
                                }
                        }

                        p->p_flags &= ~(P_TRACED | P_WAITED);
                        p->p_oppid = 0;

                        /* should we send SIGCHLD? */
                }

        sendsig:
                /*
                 * Deliver or queue signal.  If the process is stopped
                 * force it to be SACTIVE again.
                 */
                crit_enter();
                if (p->p_stat == SSTOP) {
                        p->p_xstat = data;
                        proc_unstop(p, SSTOP);
                } else if (data) {
                        ksignal(p, data);
                }
                crit_exit();
                lwkt_reltoken(&p->p_token);
                PRELE(p);
                return 0;

        case PT_WRITE_I:
        case PT_WRITE_D:
                write = 1;
                /* fallthrough */
        case PT_READ_I:
        case PT_READ_D:
                /*
                 * NOTE! uio_offset represents the offset in the target
                 * process.  The iov is in the current process (the guy
                 * making the ptrace call) so uio_td must be the current
                 * process (though for a SYSSPACE transfer it doesn't
                 * really matter).
                 */
                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;
                uio.uio_rw = write ? UIO_WRITE : UIO_READ;
                uio.uio_td = curthread;
                error = procfs_domem(curp, lp, NULL, &uio);
                if (uio.uio_resid != 0) {
                        /*
                         * XXX procfs_domem() 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 procfs_domem() 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)
                        *res = tmp;
                lwkt_reltoken(&p->p_token);
                PRELE(p);
                return (error);

        case PT_IO:
                /*
                 * NOTE! uio_offset represents the offset in the target
                 * process.  The iov is in the current process (the guy
                 * making the ptrace call) so uio_td must be the current
                 * process.
                 */
                piod = addr;
                iov.iov_base = piod->piod_addr;
                iov.iov_len = piod->piod_len;
                uio.uio_iov = &iov;
                uio.uio_iovcnt = 1;
                uio.uio_offset = (off_t)(uintptr_t)piod->piod_offs;
                uio.uio_resid = piod->piod_len;
                uio.uio_segflg = UIO_USERSPACE;
                uio.uio_td = curthread;
                switch (piod->piod_op) {
                case PIOD_READ_D:
                case PIOD_READ_I:
                        uio.uio_rw = UIO_READ;
                        break;
                case PIOD_WRITE_D:
                case PIOD_WRITE_I:
                        uio.uio_rw = UIO_WRITE;
                        break;
                default:
                        lwkt_reltoken(&p->p_token);
                        PRELE(p);
                        return (EINVAL);
                }
                error = procfs_domem(curp, lp, NULL, &uio);
                piod->piod_len -= uio.uio_resid;
                lwkt_reltoken(&p->p_token);
                PRELE(p);
                return (error);

        case PT_KILL:
                data = SIGKILL;
                goto sendsig;   /* in PT_CONTINUE above */

#ifdef PT_SETREGS
        case PT_SETREGS:
                write = 1;
                /* fallthrough */
#endif /* PT_SETREGS */
#ifdef PT_GETREGS
        case PT_GETREGS:
                /* write = 0 above */
#endif /* PT_SETREGS */
#if defined(PT_SETREGS) || defined(PT_GETREGS)
                if (!procfs_validregs(lp)) {
                        lwkt_reltoken(&p->p_token);
                        PRELE(p);
                        return EINVAL;
                } else {
                        iov.iov_base = addr;
                        iov.iov_len = sizeof(struct reg);
                        uio.uio_iov = &iov;
                        uio.uio_iovcnt = 1;
                        uio.uio_offset = 0;
                        uio.uio_resid = sizeof(struct reg);
                        uio.uio_segflg = UIO_SYSSPACE;
                        uio.uio_rw = write ? UIO_WRITE : UIO_READ;
                        uio.uio_td = curthread;
                        t = procfs_doregs(curp, lp, NULL, &uio);
                        lwkt_reltoken(&p->p_token);
                        PRELE(p);
                        return t;
                }
#endif /* defined(PT_SETREGS) || defined(PT_GETREGS) */

#ifdef PT_SETFPREGS
        case PT_SETFPREGS:
                write = 1;
                /* fallthrough */
#endif /* PT_SETFPREGS */
#ifdef PT_GETFPREGS
        case PT_GETFPREGS:
                /* write = 0 above */
#endif /* PT_SETFPREGS */
#if defined(PT_SETFPREGS) || defined(PT_GETFPREGS)
                if (!procfs_validfpregs(lp)) {
                        lwkt_reltoken(&p->p_token);
                        PRELE(p);
                        return EINVAL;
                } else {
                        iov.iov_base = addr;
                        iov.iov_len = sizeof(struct fpreg);
                        uio.uio_iov = &iov;
                        uio.uio_iovcnt = 1;
                        uio.uio_offset = 0;
                        uio.uio_resid = sizeof(struct fpreg);
                        uio.uio_segflg = UIO_SYSSPACE;
                        uio.uio_rw = write ? UIO_WRITE : UIO_READ;
                        uio.uio_td = curthread;
                        t = procfs_dofpregs(curp, lp, NULL, &uio);
                        lwkt_reltoken(&p->p_token);
                        PRELE(p);
                        return t;
                }
#endif /* defined(PT_SETFPREGS) || defined(PT_GETFPREGS) */

#ifdef PT_SETDBREGS
        case PT_SETDBREGS:
                write = 1;
                /* fallthrough */
#endif /* PT_SETDBREGS */
#ifdef PT_GETDBREGS
        case PT_GETDBREGS:
                /* write = 0 above */
#endif /* PT_SETDBREGS */
#if defined(PT_SETDBREGS) || defined(PT_GETDBREGS)
                if (!procfs_validdbregs(lp)) {
                        lwkt_reltoken(&p->p_token);
                        PRELE(p);
                        return EINVAL;
                } else {
                        iov.iov_base = addr;
                        iov.iov_len = sizeof(struct dbreg);
                        uio.uio_iov = &iov;
                        uio.uio_iovcnt = 1;
                        uio.uio_offset = 0;
                        uio.uio_resid = sizeof(struct dbreg);
                        uio.uio_segflg = UIO_SYSSPACE;
                        uio.uio_rw = write ? UIO_WRITE : UIO_READ;
                        uio.uio_td = curthread;
                        t = procfs_dodbregs(curp, lp, NULL, &uio);
                        lwkt_reltoken(&p->p_token);
                        PRELE(p);
                        return t;
                }
#endif /* defined(PT_SETDBREGS) || defined(PT_GETDBREGS) */

        default:
                break;
        }

        lwkt_reltoken(&p->p_token);
        PRELE(p);

        return 0;
}

int
trace_req(struct proc *p)
{
        return 1;
}

/*
 * stopevent()
 *
 * Stop a process because of a procfs event.  Stay stopped until p->p_step
 * is cleared (cleared by PIOCCONT in procfs).
 *
 * MPSAFE
 */
void
stopevent(struct proc *p, unsigned int event, unsigned int val) 
{
        /*
         * Set event info.  Recheck p_stops in case we are
         * racing a close() on procfs.
         */
        spin_lock(&p->p_spin);
        if ((p->p_stops & event) == 0) {
                spin_unlock(&p->p_spin);
                return;
        }
        p->p_xstat = val;
        p->p_stype = event;
        p->p_step = 1;
        tsleep_interlock(&p->p_step, 0);
        spin_unlock(&p->p_spin);

        /*
         * Wakeup any PIOCWAITing procs and wait for p_step to
         * be cleared.
         */
        for (;;) {
                wakeup(&p->p_stype);
                tsleep(&p->p_step, PINTERLOCKED, "stopevent", 0);
                spin_lock(&p->p_spin);
                if (p->p_step == 0) {
                        spin_unlock(&p->p_spin);
                        break;
                }
                tsleep_interlock(&p->p_step, 0);
                spin_unlock(&p->p_spin);
        }
}