usr/src/sys/miscfs/procfs/procfs_ctl.c

/*
 * Copyright (c) 1993 Jan-Simon Pendry
 * Copyright (c) 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Jan-Simon Pendry.
 *
 * %sccs.include.redist.c%
 *
 *      @(#)procfs_ctl.c        8.4 (Berkeley) %G%
 *
 * From:
 *      $Id: procfs_ctl.c,v 3.2 1993/12/15 09:40:17 jsp Exp $
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/time.h>
#include <sys/kernel.h>
#include <sys/proc.h>
#include <sys/vnode.h>
#include <sys/ioctl.h>
#include <sys/tty.h>
#include <sys/resource.h>
#include <sys/resourcevar.h>
#include <sys/ptrace.h>
#include <miscfs/procfs/procfs.h>

#ifndef FIX_SSTEP
#define FIX_SSTEP(p)
#endif


/*
 * True iff process (p) is in trace wait state
 * relative to process (curp)
 */
#define TRACE_WAIT_P(curp, p) \
        ((p)->p_stat == SSTOP && \
         (p)->p_pptr == (curp) && \
         ((p)->p_flag & P_TRACED))

#define PROCFS_CTL_ATTACH       1
#define PROCFS_CTL_DETACH       2
#define PROCFS_CTL_STEP         3
#define PROCFS_CTL_RUN          4
#define PROCFS_CTL_WAIT         5

static vfs_namemap_t ctlnames[] = {
        /* special /proc commands */
        { "attach",     PROCFS_CTL_ATTACH },
        { "detach",     PROCFS_CTL_DETACH },
        { "step",       PROCFS_CTL_STEP },
        { "run",        PROCFS_CTL_RUN },
        { "wait",       PROCFS_CTL_WAIT },
        { 0 },
};

static vfs_namemap_t signames[] = {
        /* regular signal names */
        { "hup",        SIGHUP },       { "int",        SIGINT },
        { "quit",       SIGQUIT },      { "ill",        SIGILL },
        { "trap",       SIGTRAP },      { "abrt",       SIGABRT },
        { "iot",        SIGIOT },       { "emt",        SIGEMT },
        { "fpe",        SIGFPE },       { "kill",       SIGKILL },
        { "bus",        SIGBUS },       { "segv",       SIGSEGV },
        { "sys",        SIGSYS },       { "pipe",       SIGPIPE },
        { "alrm",       SIGALRM },      { "term",       SIGTERM },
        { "urg",        SIGURG },       { "stop",       SIGSTOP },
        { "tstp",       SIGTSTP },      { "cont",       SIGCONT },
        { "chld",       SIGCHLD },      { "ttin",       SIGTTIN },
        { "ttou",       SIGTTOU },      { "io",         SIGIO },
        { "xcpu",       SIGXCPU },      { "xfsz",       SIGXFSZ },
        { "vtalrm",     SIGVTALRM },    { "prof",       SIGPROF },
        { "winch",      SIGWINCH },     { "info",       SIGINFO },
        { "usr1",       SIGUSR1 },      { "usr2",       SIGUSR2 },
        { 0 },
};

static int
procfs_control(curp, p, op)
        struct proc *curp;
        struct proc *p;
        int op;
{
        int error;

        /*
         * Attach - attaches the target process for debugging
         * by the calling process.
         */
        if (op == PROCFS_CTL_ATTACH) {
                /* check whether already being traced */
                if (p->p_flag & P_TRACED)
                        return (EBUSY);

                /* can't trace yourself! */
                if (p->p_pid == curp->p_pid)
                        return (EINVAL);

                /*
                 * Go ahead and set the trace flag.
                 * Save the old parent (it's reset in
                 *   _DETACH, and also in kern_exit.c:wait4()
                 * Reparent the process so that the tracing
                 *   proc gets to see all the action.
                 * Stop the target.
                 */
                p->p_flag |= P_TRACED;
                p->p_xstat = 0;         /* XXX ? */
                if (p->p_pptr != curp) {
                        p->p_oppid = p->p_pptr->p_pid;
                        proc_reparent(p, curp);
                }
                psignal(p, SIGSTOP);
                return (0);
        }

        /*
         * Target process must be stopped, owned by (curp) and
         * be set up for tracing (P_TRACED flag set).
         * Allow DETACH to take place at any time for sanity.
         * Allow WAIT any time, of course.
         */
        switch (op) {
        case PROCFS_CTL_DETACH:
        case PROCFS_CTL_WAIT:
                break;

        default:
                if (!TRACE_WAIT_P(curp, p))
                        return (EBUSY);
        }

        /*
         * do single-step fixup if needed
         */
        FIX_SSTEP(p);

        /*
         * Don't deliver any signal by default.
         * To continue with a signal, just send
         * the signal name to the ctl file
         */
        p->p_xstat = 0;

        switch (op) {
        /*
         * Detach.  Cleans up the target process, reparent it if possible
         * and set it running once more.
         */
        case PROCFS_CTL_DETACH:
                /* if not being traced, then this is a painless no-op */
                if ((p->p_flag & P_TRACED) == 0)
                        return (0);

                /* not being traced any more */
                p->p_flag &= ~P_TRACED;

                /* give process back to original parent */
                if (p->p_oppid != p->p_pptr->p_pid) {
                        struct proc *pp;

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

                p->p_oppid = 0;
                p->p_flag &= ~P_WAITED; /* XXX ? */
                wakeup((caddr_t) curp); /* XXX for CTL_WAIT below ? */

                break;

        /*
         * Step.  Let the target process execute a single instruction.
         */
        case PROCFS_CTL_STEP:
                if (error = procfs_sstep(p, 1))
                        return (error);
                break;

        /*
         * Run.  Let the target process continue running until a breakpoint
         * or some other trap.
         */
        case PROCFS_CTL_RUN:
                break;

        /*
         * Wait for the target process to stop.
         * If the target is not being traced then just wait
         * to enter
         */
        case PROCFS_CTL_WAIT:
                error = 0;
                if (p->p_flag & P_TRACED) {
                        while (error == 0 &&
                                        (p->p_stat != SSTOP) &&
                                        (p->p_flag & P_TRACED) &&
                                        (p->p_pptr == curp)) {
                                error = tsleep((caddr_t) p,
                                                PWAIT|PCATCH, "procfsx", 0);
                        }
                        if (error == 0 && !TRACE_WAIT_P(curp, p))
                                error = EBUSY;
                } else {
                        while (error == 0 && p->p_stat != SSTOP) {
                                error = tsleep((caddr_t) p,
                                                PWAIT|PCATCH, "procfs", 0);
                        }
                }
                return (error);

        default:
                panic("procfs_control");
        }

        if (p->p_stat == SSTOP)
                setrunnable(p);
        return (0);
}

int
procfs_doctl(curp, p, pfs, uio)
        struct proc *curp;
        struct pfsnode *pfs;
        struct uio *uio;
        struct proc *p;
{
        int xlen;
        int error;
        char msg[PROCFS_CTLLEN+1];
        vfs_namemap_t *nm;

        if (uio->uio_rw != UIO_WRITE)
                return (EOPNOTSUPP);

        xlen = PROCFS_CTLLEN;
        error = vfs_getuserstr(uio, msg, &xlen);
        if (error)
                return (error);

        /*
         * Map signal names into signal generation
         * or debug control.  Unknown commands and/or signals
         * return EOPNOTSUPP.
         *
         * Sending a signal while the process is being debugged
         * also has the side effect of letting the target continue
         * to run.  There is no way to single-step a signal delivery.
         */
        error = EOPNOTSUPP;

        nm = vfs_findname(ctlnames, msg, xlen);
        if (nm) {
                error = procfs_control(curp, p, nm->nm_val);
        } else {
                nm = vfs_findname(signames, msg, xlen);
                if (nm) {
                        if (TRACE_WAIT_P(curp, p)) {
                                p->p_xstat = nm->nm_val;
                                FIX_SSTEP(p);
                                setrunnable(p);
                        } else {
                                psignal(p, nm->nm_val);
                        }
                        error = 0;
                }
        }

        return (error);
}