sys/vfs/procfs/procfs_ctl.c

   1 /*
   2  * Copyright (c) 1993 Jan-Simon Pendry
   3  * Copyright (c) 1993
   4  *      The Regents of the University of California.  All rights reserved.
   5  *
   6  * This code is derived from software contributed to Berkeley by
   7  * Jan-Simon Pendry.
   8  *
   9  * Redistribution and use in source and binary forms, with or without
  10  * modification, are permitted provided that the following conditions
  11  * are met:
  12  * 1. Redistributions of source code must retain the above copyright
  13  *    notice, this list of conditions and the following disclaimer.
  14  * 2. Redistributions in binary form must reproduce the above copyright
  15  *    notice, this list of conditions and the following disclaimer in the
  16  *    documentation and/or other materials provided with the distribution.
  17  * 3. All advertising materials mentioning features or use of this software
  18  *    must display the following acknowledgement:
  19  *      This product includes software developed by the University of
  20  *      California, Berkeley and its contributors.
  21  * 4. Neither the name of the University nor the names of its contributors
  22  *    may be used to endorse or promote products derived from this software
  23  *    without specific prior written permission.
  24  *
  25  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  26  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  27  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  28  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  29  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  30  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  31  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  32  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  33  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  34  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  35  * SUCH DAMAGE.
  36  *
  37  *      @(#)procfs_ctl.c        8.4 (Berkeley) 6/15/94
  38  *
  39  * From:
  40  * $FreeBSD: src/sys/miscfs/procfs/procfs_ctl.c,v 1.20.2.2 2002/01/22 17:22:59 nectar Exp $
  41  * $DragonFly: src/sys/vfs/procfs/procfs_ctl.c,v 1.16 2007/03/12 21:08:15 corecode Exp $
  42  */
  43
  44 #include <sys/param.h>
  45 #include <sys/systm.h>
  46 #include <sys/proc.h>
  47 #include <sys/vnode.h>
  48 #include <sys/ptrace.h>
  49 #include <sys/signalvar.h>
  50 #include <sys/signal2.h>
  51 #include <vfs/procfs/procfs.h>
  52
  53 #include <vm/vm.h>
  54
  55 #ifndef FIX_SSTEP
  56 #define FIX_SSTEP(lp)
  57 #endif
  58
  59 /*
  60  * True iff process (p) is in trace wait state
  61  * relative to process (curp)
  62  */
  63 #define TRACE_WAIT_P(curp, p) \
  64         (((p)->p_stat == SSTOP) && \
  65          (p)->p_pptr == (curp) && \
  66          ((p)->p_flag & P_TRACED))
  67
  68 #define PROCFS_CTL_ATTACH       1
  69 #define PROCFS_CTL_DETACH       2
  70 #define PROCFS_CTL_STEP         3
  71 #define PROCFS_CTL_RUN          4
  72 #define PROCFS_CTL_WAIT         5
  73
  74 static vfs_namemap_t ctlnames[] = {
  75         /* special /proc commands */
  76         { "attach",     PROCFS_CTL_ATTACH },
  77         { "detach",     PROCFS_CTL_DETACH },
  78         { "step",       PROCFS_CTL_STEP },
  79         { "run",        PROCFS_CTL_RUN },
  80         { "wait",       PROCFS_CTL_WAIT },
  81         { 0 },
  82 };
  83
  84 static vfs_namemap_t signames[] = {
  85         /* regular signal names */
  86         { "hup",        SIGHUP },       { "int",        SIGINT },
  87         { "quit",       SIGQUIT },      { "ill",        SIGILL },
  88         { "trap",       SIGTRAP },      { "abrt",       SIGABRT },
  89         { "iot",        SIGIOT },       { "emt",        SIGEMT },
  90         { "fpe",        SIGFPE },       { "kill",       SIGKILL },
  91         { "bus",        SIGBUS },       { "segv",       SIGSEGV },
  92         { "sys",        SIGSYS },       { "pipe",       SIGPIPE },
  93         { "alrm",       SIGALRM },      { "term",       SIGTERM },
  94         { "urg",        SIGURG },       { "stop",       SIGSTOP },
  95         { "tstp",       SIGTSTP },      { "cont",       SIGCONT },
  96         { "chld",       SIGCHLD },      { "ttin",       SIGTTIN },
  97         { "ttou",       SIGTTOU },      { "io",         SIGIO },
  98         { "xcpu",       SIGXCPU },      { "xfsz",       SIGXFSZ },
  99         { "vtalrm",     SIGVTALRM },    { "prof",       SIGPROF },
 100         { "winch",      SIGWINCH },     { "info",       SIGINFO },
 101         { "usr1",       SIGUSR1 },      { "usr2",       SIGUSR2 },
 102         { 0 },
 103 };
 104
 105 static int      procfs_control (struct proc *curp, struct lwp *lp, int op);
 106
 107 static int
 108 procfs_control(struct proc *curp, struct lwp *lp, int op)
 109 {
 110         struct proc *p = lp->lwp_proc;
 111         int error;
 112
 113         /* Can't trace a process that's currently exec'ing. */
 114         if ((p->p_flag & P_INEXEC) != 0)
 115                 return EAGAIN;
 116         /*
 117          * Authorization check: rely on normal debugging protection, except
 118          * allow processes to disengage debugging on a process onto which
 119          * they have previously attached, but no longer have permission to
 120          * debug.
 121          */
 122         if (op != PROCFS_CTL_DETACH) {
 123                 if (securelevel > 0 && p->p_pid == 1)
 124                         return (EPERM);
 125
 126                 if (!CHECKIO(curp, p) || p_trespass(curp->p_ucred, p->p_ucred))
 127                         return (EPERM);
 128         }
 129
 130         /*
 131          * Attach - attaches the target process for debugging
 132          * by the calling process.
 133          */
 134         if (op == PROCFS_CTL_ATTACH) {
 135                 /* check whether already being traced */
 136                 if (p->p_flag & P_TRACED)
 137                         return (EBUSY);
 138
 139                 /* can't trace yourself! */
 140                 if (p->p_pid == curp->p_pid)
 141                         return (EINVAL);
 142
 143                 /*
 144                  * Go ahead and set the trace flag.
 145                  * Save the old parent (it's reset in
 146                  *   _DETACH, and also in kern_exit.c:wait4()
 147                  * Reparent the process so that the tracing
 148                  *   proc gets to see all the action.
 149                  * Stop the target.
 150                  */
 151                 p->p_flag |= P_TRACED;
 152                 faultin(p);
 153                 p->p_xstat = 0;         /* XXX ? */
 154                 if (p->p_pptr != curp) {
 155                         p->p_oppid = p->p_pptr->p_pid;
 156                         proc_reparent(p, curp);
 157                 }
 158                 proc_stop(p);
 159                 return (0);
 160         }
 161
 162         /*
 163          * Target process must be stopped, owned by (curp) and
 164          * be set up for tracing (P_TRACED flag set).
 165          * Allow DETACH to take place at any time for sanity.
 166          * Allow WAIT any time, of course.
 167          */
 168         switch (op) {
 169         case PROCFS_CTL_DETACH:
 170         case PROCFS_CTL_WAIT:
 171                 break;
 172
 173         default:
 174                 if (!TRACE_WAIT_P(curp, p))
 175                         return (EBUSY);
 176         }
 177
 178
 179 #ifdef FIX_SSTEP
 180         /*
 181          * do single-step fixup if needed
 182          */
 183         FIX_SSTEP(lp);
 184 #endif
 185
 186         /*
 187          * Don't deliver any signal by default.
 188          * To continue with a signal, just send
 189          * the signal name to the ctl file
 190          */
 191         p->p_xstat = 0;
 192
 193         switch (op) {
 194         /*
 195          * Detach.  Cleans up the target process, reparent it if possible
 196          * and set it running once more.
 197          */
 198         case PROCFS_CTL_DETACH:
 199                 /* if not being traced, then this is a painless no-op */
 200                 if ((p->p_flag & P_TRACED) == 0)
 201                         return (0);
 202
 203                 /* not being traced any more */
 204                 p->p_flag &= ~P_TRACED;
 205
 206                 /* remove pending SIGTRAP, else the process will die */
 207                 lwp_delsig(lp, SIGTRAP);
 208
 209                 /* give process back to original parent */
 210                 if (p->p_oppid != p->p_pptr->p_pid) {
 211                         struct proc *pp;
 212
 213                         pp = pfind(p->p_oppid);
 214                         if (pp)
 215                                 proc_reparent(p, pp);
 216                 }
 217
 218                 p->p_oppid = 0;
 219                 p->p_flag &= ~P_WAITED; /* XXX ? */
 220                 wakeup((caddr_t) curp); /* XXX for CTL_WAIT below ? */
 221
 222                 break;
 223
 224         /*
 225          * Step.  Let the target process execute a single instruction.
 226          */
 227         case PROCFS_CTL_STEP:
 228                 LWPHOLD(lp);
 229                 error = procfs_sstep(lp);
 230                 LWPRELE(lp);
 231                 if (error)
 232                         return (error);
 233                 break;
 234
 235         /*
 236          * Run.  Let the target process continue running until a breakpoint
 237          * or some other trap.
 238          */
 239         case PROCFS_CTL_RUN:
 240                 break;
 241
 242         /*
 243          * Wait for the target process to stop.
 244          * If the target is not being traced then just wait
 245          * to enter
 246          */
 247         case PROCFS_CTL_WAIT:
 248                 error = 0;
 249                 if (p->p_flag & P_TRACED) {
 250                         while (error == 0 &&
 251                                         p->p_stat != SSTOP &&
 252                                         (p->p_flag & P_TRACED) &&
 253                                         (p->p_pptr == curp)) {
 254                                 error = tsleep((caddr_t) p,
 255                                                 PCATCH, "procfsx", 0);
 256                         }
 257                         if (error == 0 && !TRACE_WAIT_P(curp, p))
 258                                 error = EBUSY;
 259                 } else {
 260                         while (error == 0 && p->p_stat != SSTOP) {
 261                                 error = tsleep((caddr_t) p,
 262                                                 PCATCH, "procfs", 0);
 263                         }
 264                 }
 265                 return (error);
 266
 267         default:
 268                 panic("procfs_control");
 269         }
 270
 271         /*
 272          * If the process is in a stopped state, make it runnable again.
 273          * Do not set LWP_BREAKTSLEEP - that is, do not break a tsleep that
 274          * might be in progress.
 275          */
 276         if (p->p_stat == SSTOP)
 277                 proc_unstop(p);
 278         return (0);
 279 }
 280
 281 int
 282 procfs_doctl(struct proc *curp, struct lwp *lp, struct pfsnode *pfs,
 283              struct uio *uio)
 284 {
 285         struct proc *p = lp->lwp_proc;
 286         int xlen;
 287         int error;
 288         char msg[PROCFS_CTLLEN+1];
 289         vfs_namemap_t *nm;
 290
 291         if (uio->uio_rw != UIO_WRITE)
 292                 return (EOPNOTSUPP);
 293
 294         xlen = PROCFS_CTLLEN;
 295         error = vfs_getuserstr(uio, msg, &xlen);
 296         if (error)
 297                 return (error);
 298
 299         /*
 300          * Map signal names into signal generation
 301          * or debug control.  Unknown commands and/or signals
 302          * return EOPNOTSUPP.
 303          *
 304          * Sending a signal while the process is being debugged
 305          * also has the side effect of letting the target continue
 306          * to run.  There is no way to single-step a signal delivery.
 307          */
 308         error = EOPNOTSUPP;
 309
 310         nm = vfs_findname(ctlnames, msg, xlen);
 311         if (nm) {
 312                 error = procfs_control(curp, lp, nm->nm_val);
 313         } else {
 314                 nm = vfs_findname(signames, msg, xlen);
 315                 if (nm) {
 316                         if (TRACE_WAIT_P(curp, p)) {
 317                                 p->p_xstat = nm->nm_val;
 318 #ifdef FIX_SSTEP
 319                                 FIX_SSTEP(lp);
 320 #endif
 321                                 /*
 322                                  * Make the process runnable but do not
 323                                  * break its tsleep.
 324                                  */
 325                                 proc_unstop(p);
 326                         } else {
 327                                 ksignal(p, nm->nm_val);
 328                         }
 329                         error = 0;
 330                 }
 331         }
 332
 333         return (error);
 334 }