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 1.13 2007/02/21 15:46:48 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 <vfs/procfs/procfs.h>
  51
  52 #include <vm/vm.h>
  53
  54 #ifndef FIX_SSTEP
  55 #define FIX_SSTEP(lp)
  56 #endif
  57
  58 /*
  59  * True iff process (p) is in trace wait state
  60  * relative to process (curp)
  61  */
  62 #define TRACE_WAIT_P(curp, p) \
  63         (((p)->p_stat == SSTOP) && \
  64          (p)->p_pptr == (curp) && \
  65          ((p)->p_flag & P_TRACED))
  66
  67 #define PROCFS_CTL_ATTACH       1
  68 #define PROCFS_CTL_DETACH       2
  69 #define PROCFS_CTL_STEP         3
  70 #define PROCFS_CTL_RUN          4
  71 #define PROCFS_CTL_WAIT         5
  72
  73 static vfs_namemap_t ctlnames[] = {
  74         /* special /proc commands */
  75         { "attach",     PROCFS_CTL_ATTACH },
  76         { "detach",     PROCFS_CTL_DETACH },
  77         { "step",       PROCFS_CTL_STEP },
  78         { "run",        PROCFS_CTL_RUN },
  79         { "wait",       PROCFS_CTL_WAIT },
  80         { 0 },
  81 };
  82
  83 static vfs_namemap_t signames[] = {
  84         /* regular signal names */
  85         { "hup",        SIGHUP },       { "int",        SIGINT },
  86         { "quit",       SIGQUIT },      { "ill",        SIGILL },
  87         { "trap",       SIGTRAP },      { "abrt",       SIGABRT },
  88         { "iot",        SIGIOT },       { "emt",        SIGEMT },
  89         { "fpe",        SIGFPE },       { "kill",       SIGKILL },
  90         { "bus",        SIGBUS },       { "segv",       SIGSEGV },
  91         { "sys",        SIGSYS },       { "pipe",       SIGPIPE },
  92         { "alrm",       SIGALRM },      { "term",       SIGTERM },
  93         { "urg",        SIGURG },       { "stop",       SIGSTOP },
  94         { "tstp",       SIGTSTP },      { "cont",       SIGCONT },
  95         { "chld",       SIGCHLD },      { "ttin",       SIGTTIN },
  96         { "ttou",       SIGTTOU },      { "io",         SIGIO },
  97         { "xcpu",       SIGXCPU },      { "xfsz",       SIGXFSZ },
  98         { "vtalrm",     SIGVTALRM },    { "prof",       SIGPROF },
  99         { "winch",      SIGWINCH },     { "info",       SIGINFO },
 100         { "usr1",       SIGUSR1 },      { "usr2",       SIGUSR2 },
 101         { 0 },
 102 };
 103
 104 static int      procfs_control (struct proc *curp, struct lwp *lp, int op);
 105
 106 static int
 107 procfs_control(struct proc *curp, struct lwp *lp, int op)
 108 {
 109         struct proc *p = lp->lwp_proc;
 110         int error;
 111
 112         /* Can't trace a process that's currently exec'ing. */
 113         if ((p->p_flag & P_INEXEC) != 0)
 114                 return EAGAIN;
 115         /*
 116          * Authorization check: rely on normal debugging protection, except
 117          * allow processes to disengage debugging on a process onto which
 118          * they have previously attached, but no longer have permission to
 119          * debug.
 120          */
 121         if (op != PROCFS_CTL_DETACH) {
 122                 if (securelevel > 0 && p->p_pid == 1)
 123                         return (EPERM);
 124
 125                 if (!CHECKIO(curp, p) || p_trespass(curp->p_ucred, p->p_ucred))
 126                         return (EPERM);
 127         }
 128
 129         /*
 130          * Attach - attaches the target process for debugging
 131          * by the calling process.
 132          */
 133         if (op == PROCFS_CTL_ATTACH) {
 134                 /* check whether already being traced */
 135                 if (p->p_flag & P_TRACED)
 136                         return (EBUSY);
 137
 138                 /* can't trace yourself! */
 139                 if (p->p_pid == curp->p_pid)
 140                         return (EINVAL);
 141
 142                 /*
 143                  * Go ahead and set the trace flag.
 144                  * Save the old parent (it's reset in
 145                  *   _DETACH, and also in kern_exit.c:wait4()
 146                  * Reparent the process so that the tracing
 147                  *   proc gets to see all the action.
 148                  * Stop the target.
 149                  */
 150                 p->p_flag |= P_TRACED;
 151                 faultin(p);
 152                 p->p_xstat = 0;         /* XXX ? */
 153                 if (p->p_pptr != curp) {
 154                         p->p_oppid = p->p_pptr->p_pid;
 155                         proc_reparent(p, curp);
 156                 }
 157                 ksignal(p, SIGSTOP);
 158                 return (0);
 159         }
 160
 161         /*
 162          * Target process must be stopped, owned by (curp) and
 163          * be set up for tracing (P_TRACED flag set).
 164          * Allow DETACH to take place at any time for sanity.
 165          * Allow WAIT any time, of course.
 166          */
 167         switch (op) {
 168         case PROCFS_CTL_DETACH:
 169         case PROCFS_CTL_WAIT:
 170                 break;
 171
 172         default:
 173                 if (!TRACE_WAIT_P(curp, p))
 174                         return (EBUSY);
 175         }
 176
 177
 178 #ifdef FIX_SSTEP
 179         /*
 180          * do single-step fixup if needed
 181          */
 182         FIX_SSTEP(lp);
 183 #endif
 184
 185         /*
 186          * Don't deliver any signal by default.
 187          * To continue with a signal, just send
 188          * the signal name to the ctl file
 189          */
 190         p->p_xstat = 0;
 191
 192         switch (op) {
 193         /*
 194          * Detach.  Cleans up the target process, reparent it if possible
 195          * and set it running once more.
 196          */
 197         case PROCFS_CTL_DETACH:
 198                 /* if not being traced, then this is a painless no-op */
 199                 if ((p->p_flag & P_TRACED) == 0)
 200                         return (0);
 201
 202                 /* not being traced any more */
 203                 p->p_flag &= ~P_TRACED;
 204
 205                 /* remove pending SIGTRAP, else the process will die */
 206                 lwp_delsig(lp, SIGTRAP);
 207
 208                 /* give process back to original parent */
 209                 if (p->p_oppid != p->p_pptr->p_pid) {
 210                         struct proc *pp;
 211
 212                         pp = pfind(p->p_oppid);
 213                         if (pp)
 214                                 proc_reparent(p, pp);
 215                 }
 216
 217                 p->p_oppid = 0;
 218                 p->p_flag &= ~P_WAITED; /* XXX ? */
 219                 wakeup((caddr_t) curp); /* XXX for CTL_WAIT below ? */
 220
 221                 break;
 222
 223         /*
 224          * Step.  Let the target process execute a single instruction.
 225          */
 226         case PROCFS_CTL_STEP:
 227                 LWPHOLD(lp);
 228                 error = procfs_sstep(lp);
 229                 LWPRELE(lp);
 230                 if (error)
 231                         return (error);
 232                 break;
 233
 234         /*
 235          * Run.  Let the target process continue running until a breakpoint
 236          * or some other trap.
 237          */
 238         case PROCFS_CTL_RUN:
 239                 break;
 240
 241         /*
 242          * Wait for the target process to stop.
 243          * If the target is not being traced then just wait
 244          * to enter
 245          */
 246         case PROCFS_CTL_WAIT:
 247                 error = 0;
 248                 if (p->p_flag & P_TRACED) {
 249                         while (error == 0 &&
 250                                         p->p_stat != SSTOP &&
 251                                         (p->p_flag & P_TRACED) &&
 252                                         (p->p_pptr == curp)) {
 253                                 error = tsleep((caddr_t) p,
 254                                                 PCATCH, "procfsx", 0);
 255                         }
 256                         if (error == 0 && !TRACE_WAIT_P(curp, p))
 257                                 error = EBUSY;
 258                 } else {
 259                         while (error == 0 && p->p_stat != SSTOP) {
 260                                 error = tsleep((caddr_t) p,
 261                                                 PCATCH, "procfs", 0);
 262                         }
 263                 }
 264                 return (error);
 265
 266         default:
 267                 panic("procfs_control");
 268         }
 269
 270         /*
 271          * If the process is in a stopped state, make it runnable again.
 272          * Do not set LWP_BREAKTSLEEP - that is, do not break a tsleep that
 273          * might be in progress.
 274          */
 275         if (p->p_stat == SSTOP)
 276                 proc_unstop(p);
 277         return (0);
 278 }
 279
 280 int
 281 procfs_doctl(struct proc *curp, struct lwp *lp, struct pfsnode *pfs,
 282              struct uio *uio)
 283 {
 284         struct proc *p = lp->lwp_proc;
 285         int xlen;
 286         int error;
 287         char msg[PROCFS_CTLLEN+1];
 288         vfs_namemap_t *nm;
 289
 290         if (uio->uio_rw != UIO_WRITE)
 291                 return (EOPNOTSUPP);
 292
 293         xlen = PROCFS_CTLLEN;
 294         error = vfs_getuserstr(uio, msg, &xlen);
 295         if (error)
 296                 return (error);
 297
 298         /*
 299          * Map signal names into signal generation
 300          * or debug control.  Unknown commands and/or signals
 301          * return EOPNOTSUPP.
 302          *
 303          * Sending a signal while the process is being debugged
 304          * also has the side effect of letting the target continue
 305          * to run.  There is no way to single-step a signal delivery.
 306          */
 307         error = EOPNOTSUPP;
 308
 309         nm = vfs_findname(ctlnames, msg, xlen);
 310         if (nm) {
 311                 error = procfs_control(curp, lp, nm->nm_val);
 312         } else {
 313                 nm = vfs_findname(signames, msg, xlen);
 314                 if (nm) {
 315                         if (TRACE_WAIT_P(curp, p)) {
 316                                 p->p_xstat = nm->nm_val;
 317 #ifdef FIX_SSTEP
 318                                 FIX_SSTEP(lp);
 319 #endif
 320                                 /*
 321                                  * Make the process runnable but do not
 322                                  * break its tsleep.
 323                                  */
 324                                 proc_unstop(p);
 325                         } else {
 326                                 ksignal(p, nm->nm_val);
 327                         }
 328                         error = 0;
 329                 }
 330         }
 331
 332         return (error);
 333 }