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/priv.h>
  48 #include <sys/vnode.h>
  49 #include <sys/ptrace.h>
  50 #include <sys/signalvar.h>
  51 #include <sys/signal2.h>
  52 #include <vfs/procfs/procfs.h>
  53
  54 #include <vm/vm.h>
  55
  56 #ifndef FIX_SSTEP
  57 #define FIX_SSTEP(lp)
  58 #endif
  59
  60 /*
  61  * True iff process (p) is in trace wait state
  62  * relative to process (curp)
  63  */
  64 #define TRACE_WAIT_P(curp, p) \
  65         (((p)->p_stat == SSTOP) && \
  66          (p)->p_pptr == (curp) && \
  67          ((p)->p_flag & P_TRACED))
  68
  69 #define PROCFS_CTL_ATTACH       1
  70 #define PROCFS_CTL_DETACH       2
  71 #define PROCFS_CTL_STEP         3
  72 #define PROCFS_CTL_RUN          4
  73 #define PROCFS_CTL_WAIT         5
  74
  75 static vfs_namemap_t ctlnames[] = {
  76         /* special /proc commands */
  77         { "attach",     PROCFS_CTL_ATTACH },
  78         { "detach",     PROCFS_CTL_DETACH },
  79         { "step",       PROCFS_CTL_STEP },
  80         { "run",        PROCFS_CTL_RUN },
  81         { "wait",       PROCFS_CTL_WAIT },
  82         { 0 },
  83 };
  84
  85 static vfs_namemap_t signames[] = {
  86         /* regular signal names */
  87         { "hup",        SIGHUP },       { "int",        SIGINT },
  88         { "quit",       SIGQUIT },      { "ill",        SIGILL },
  89         { "trap",       SIGTRAP },      { "abrt",       SIGABRT },
  90         { "iot",        SIGIOT },       { "emt",        SIGEMT },
  91         { "fpe",        SIGFPE },       { "kill",       SIGKILL },
  92         { "bus",        SIGBUS },       { "segv",       SIGSEGV },
  93         { "sys",        SIGSYS },       { "pipe",       SIGPIPE },
  94         { "alrm",       SIGALRM },      { "term",       SIGTERM },
  95         { "urg",        SIGURG },       { "stop",       SIGSTOP },
  96         { "tstp",       SIGTSTP },      { "cont",       SIGCONT },
  97         { "chld",       SIGCHLD },      { "ttin",       SIGTTIN },
  98         { "ttou",       SIGTTOU },      { "io",         SIGIO },
  99         { "xcpu",       SIGXCPU },      { "xfsz",       SIGXFSZ },
 100         { "vtalrm",     SIGVTALRM },    { "prof",       SIGPROF },
 101         { "winch",      SIGWINCH },     { "info",       SIGINFO },
 102         { "usr1",       SIGUSR1 },      { "usr2",       SIGUSR2 },
 103         { 0 },
 104 };
 105
 106 static int      procfs_control (struct proc *curp, struct lwp *lp, int op);
 107
 108 static int
 109 procfs_control(struct proc *curp, struct lwp *lp, int op)
 110 {
 111         struct proc *p = lp->lwp_proc;
 112         int error;
 113
 114         /* Can't trace a process that's currently exec'ing. */
 115         if ((p->p_flag & P_INEXEC) != 0)
 116                 return EAGAIN;
 117         /*
 118          * Authorization check: rely on normal debugging protection, except
 119          * allow processes to disengage debugging on a process onto which
 120          * they have previously attached, but no longer have permission to
 121          * debug.
 122          */
 123         if (op != PROCFS_CTL_DETACH) {
 124                 if (securelevel > 0 && p->p_pid == 1)
 125                         return (EPERM);
 126
 127                 if (!CHECKIO(curp, p) || p_trespass(curp->p_ucred, p->p_ucred))
 128                         return (EPERM);
 129         }
 130
 131         /*
 132          * Attach - attaches the target process for debugging
 133          * by the calling process.
 134          */
 135         if (op == PROCFS_CTL_ATTACH) {
 136                 /* check whether already being traced */
 137                 if (p->p_flag & P_TRACED)
 138                         return (EBUSY);
 139
 140                 /* can't trace yourself! */
 141                 if (p->p_pid == curp->p_pid)
 142                         return (EINVAL);
 143
 144                 /*
 145                  * Go ahead and set the trace flag.
 146                  * Save the old parent (it's reset in
 147                  *   _DETACH, and also in kern_exit.c:wait4()
 148                  * Reparent the process so that the tracing
 149                  *   proc gets to see all the action.
 150                  * Stop the target.
 151                  */
 152                 p->p_flag |= P_TRACED;
 153                 faultin(p);
 154                 p->p_xstat = 0;         /* XXX ? */
 155                 if (p->p_pptr != curp) {
 156                         p->p_oppid = p->p_pptr->p_pid;
 157                         proc_reparent(p, curp);
 158                 }
 159                 proc_stop(p);
 160                 return (0);
 161         }
 162
 163         /*
 164          * Target process must be stopped, owned by (curp) and
 165          * be set up for tracing (P_TRACED flag set).
 166          * Allow DETACH to take place at any time for sanity.
 167          * Allow WAIT any time, of course.
 168          */
 169         switch (op) {
 170         case PROCFS_CTL_DETACH:
 171         case PROCFS_CTL_WAIT:
 172                 break;
 173
 174         default:
 175                 if (!TRACE_WAIT_P(curp, p))
 176                         return (EBUSY);
 177         }
 178
 179
 180 #ifdef FIX_SSTEP
 181         /*
 182          * do single-step fixup if needed
 183          */
 184         FIX_SSTEP(lp);
 185 #endif
 186
 187         /*
 188          * Don't deliver any signal by default.
 189          * To continue with a signal, just send
 190          * the signal name to the ctl file
 191          */
 192         p->p_xstat = 0;
 193
 194         switch (op) {
 195         /*
 196          * Detach.  Cleans up the target process, reparent it if possible
 197          * and set it running once more.
 198          */
 199         case PROCFS_CTL_DETACH:
 200                 /* if not being traced, then this is a painless no-op */
 201                 if ((p->p_flag & P_TRACED) == 0)
 202                         return (0);
 203
 204                 /* not being traced any more */
 205                 p->p_flag &= ~P_TRACED;
 206
 207                 /* remove pending SIGTRAP, else the process will die */
 208                 lwp_delsig(lp, SIGTRAP);
 209
 210                 /* give process back to original parent */
 211                 if (p->p_oppid != p->p_pptr->p_pid) {
 212                         struct proc *pp;
 213
 214                         pp = pfind(p->p_oppid);
 215                         if (pp)
 216                                 proc_reparent(p, pp);
 217                 }
 218
 219                 p->p_oppid = 0;
 220                 p->p_flag &= ~P_WAITED; /* XXX ? */
 221                 wakeup((caddr_t) curp); /* XXX for CTL_WAIT below ? */
 222
 223                 break;
 224
 225         /*
 226          * Step.  Let the target process execute a single instruction.
 227          */
 228         case PROCFS_CTL_STEP:
 229                 LWPHOLD(lp);
 230                 error = procfs_sstep(lp);
 231                 LWPRELE(lp);
 232                 if (error)
 233                         return (error);
 234                 break;
 235
 236         /*
 237          * Run.  Let the target process continue running until a breakpoint
 238          * or some other trap.
 239          */
 240         case PROCFS_CTL_RUN:
 241                 break;
 242
 243         /*
 244          * Wait for the target process to stop.
 245          * If the target is not being traced then just wait
 246          * to enter
 247          */
 248         case PROCFS_CTL_WAIT:
 249                 error = 0;
 250                 if (p->p_flag & P_TRACED) {
 251                         while (error == 0 &&
 252                                         p->p_stat != SSTOP &&
 253                                         (p->p_flag & P_TRACED) &&
 254                                         (p->p_pptr == curp)) {
 255                                 error = tsleep((caddr_t) p,
 256                                                 PCATCH, "procfsx", 0);
 257                         }
 258                         if (error == 0 && !TRACE_WAIT_P(curp, p))
 259                                 error = EBUSY;
 260                 } else {
 261                         while (error == 0 && p->p_stat != SSTOP) {
 262                                 error = tsleep((caddr_t) p,
 263                                                 PCATCH, "procfs", 0);
 264                         }
 265                 }
 266                 return (error);
 267
 268         default:
 269                 panic("procfs_control");
 270         }
 271
 272         /*
 273          * If the process is in a stopped state, make it runnable again.
 274          * Do not set LWP_BREAKTSLEEP - that is, do not break a tsleep that
 275          * might be in progress.
 276          */
 277         if (p->p_stat == SSTOP)
 278                 proc_unstop(p);
 279         return (0);
 280 }
 281
 282 int
 283 procfs_doctl(struct proc *curp, struct lwp *lp, struct pfsnode *pfs,
 284              struct uio *uio)
 285 {
 286         struct proc *p = lp->lwp_proc;
 287         int xlen;
 288         int error;
 289         char msg[PROCFS_CTLLEN+1];
 290         vfs_namemap_t *nm;
 291
 292         if (uio->uio_rw != UIO_WRITE)
 293                 return (EOPNOTSUPP);
 294
 295         xlen = PROCFS_CTLLEN;
 296         error = vfs_getuserstr(uio, msg, &xlen);
 297         if (error)
 298                 return (error);
 299
 300         /*
 301          * Map signal names into signal generation
 302          * or debug control.  Unknown commands and/or signals
 303          * return EOPNOTSUPP.
 304          *
 305          * Sending a signal while the process is being debugged
 306          * also has the side effect of letting the target continue
 307          * to run.  There is no way to single-step a signal delivery.
 308          */
 309         error = EOPNOTSUPP;
 310
 311         nm = vfs_findname(ctlnames, msg, xlen);
 312         if (nm) {
 313                 error = procfs_control(curp, lp, nm->nm_val);
 314         } else {
 315                 nm = vfs_findname(signames, msg, xlen);
 316                 if (nm) {
 317                         if (TRACE_WAIT_P(curp, p)) {
 318                                 p->p_xstat = nm->nm_val;
 319 #ifdef FIX_SSTEP
 320                                 FIX_SSTEP(lp);
 321 #endif
 322                                 /*
 323                                  * Make the process runnable but do not
 324                                  * break its tsleep.
 325                                  */
 326                                 proc_unstop(p);
 327                         } else {
 328                                 ksignal(p, nm->nm_val);
 329                         }
 330                         error = 0;
 331                 }
 332         }
 333
 334         return (error);
 335 }