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. Neither the name of the University nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  *
  33  *      @(#)procfs_ctl.c        8.4 (Berkeley) 6/15/94
  34  *
  35  * From:
  36  * $FreeBSD: src/sys/miscfs/procfs/procfs_ctl.c,v 1.20.2.2 2002/01/22 17:22:59 nectar Exp $
  37  * $DragonFly: src/sys/vfs/procfs/procfs_ctl.c,v 1.16 2007/03/12 21:08:15 corecode Exp $
  38  */
  39
  40 #include <sys/param.h>
  41 #include <sys/systm.h>
  42 #include <sys/proc.h>
  43 #include <sys/priv.h>
  44 #include <sys/vnode.h>
  45 #include <sys/ptrace.h>
  46 #include <sys/signalvar.h>
  47 #include <vfs/procfs/procfs.h>
  48
  49 #include <sys/signal2.h>
  50 #include <sys/thread2.h>
  51 #include <sys/mplock2.h>
  52 #include <sys/spinlock2.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_flags & 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         ASSERT_LWKT_TOKEN_HELD(&p->p_token);
 115
 116         /* Can't trace a process that's currently exec'ing. */
 117         if ((p->p_flags & P_INEXEC) != 0)
 118                 return EAGAIN;
 119         /*
 120          * Authorization check: rely on normal debugging protection, except
 121          * allow processes to disengage debugging on a process onto which
 122          * they have previously attached, but no longer have permission to
 123          * debug.
 124          */
 125         if (op != PROCFS_CTL_DETACH) {
 126                 if (securelevel > 0 && p->p_pid == 1)
 127                         return (EPERM);
 128
 129                 if (!CHECKIO(curp, p) || p_trespass(curp->p_ucred, p->p_ucred))
 130                         return (EPERM);
 131         }
 132
 133         /*
 134          * Attach - attaches the target process for debugging
 135          * by the calling process.
 136          */
 137         if (op == PROCFS_CTL_ATTACH) {
 138                 /* check whether already being traced */
 139                 if (p->p_flags & P_TRACED)
 140                         return (EBUSY);
 141
 142                 /* can't trace yourself! */
 143                 if (p->p_pid == curp->p_pid)
 144                         return (EINVAL);
 145
 146                 /*
 147                  * Go ahead and set the trace flag.
 148                  * Save the old parent (it's reset in
 149                  *   _DETACH, and also in kern_exit.c:wait4()
 150                  * Reparent the process so that the tracing
 151                  *   proc gets to see all the action.
 152                  * Stop the target.
 153                  */
 154                 p->p_flags |= P_TRACED;
 155                 faultin(p);
 156                 p->p_xstat = 0;         /* XXX ? */
 157                 if (p->p_pptr != curp) {
 158                         p->p_oppid = p->p_pptr->p_pid;
 159                         proc_reparent(p, curp);
 160                 }
 161                 proc_stop(p, SSTOP);
 162                 return (0);
 163         }
 164
 165         /*
 166          * Target process must be stopped, owned by (curp) and
 167          * be set up for tracing (P_TRACED flag set).
 168          * Allow DETACH to take place at any time for sanity.
 169          * Allow WAIT any time, of course.
 170          */
 171         switch (op) {
 172         case PROCFS_CTL_DETACH:
 173         case PROCFS_CTL_WAIT:
 174                 break;
 175
 176         default:
 177                 if (!TRACE_WAIT_P(curp, p))
 178                         return (EBUSY);
 179         }
 180
 181
 182 #ifdef FIX_SSTEP
 183         /*
 184          * do single-step fixup if needed
 185          */
 186         FIX_SSTEP(lp);
 187 #endif
 188
 189         /*
 190          * Don't deliver any signal by default.
 191          * To continue with a signal, just send
 192          * the signal name to the ctl file
 193          */
 194         p->p_xstat = 0;
 195
 196         switch (op) {
 197         /*
 198          * Detach.  Cleans up the target process, reparent it if possible
 199          * and set it running once more.
 200          */
 201         case PROCFS_CTL_DETACH:
 202                 /* if not being traced, then this is a painless no-op */
 203                 if ((p->p_flags & P_TRACED) == 0)
 204                         return (0);
 205
 206                 /* not being traced any more */
 207                 p->p_flags &= ~P_TRACED;
 208
 209                 /* remove pending SIGTRAP, else the process will die */
 210                 spin_lock(&lp->lwp_spin);
 211                 lwp_delsig(lp, SIGTRAP, 1);
 212                 spin_unlock(&lp->lwp_spin);
 213
 214                 /* give process back to original parent */
 215                 if (p->p_oppid != p->p_pptr->p_pid) {
 216                         struct proc *pp;
 217
 218                         pp = pfs_pfind(p->p_oppid);
 219                         if (pp) {
 220                                 proc_reparent(p, pp);
 221                                 pfs_pdone(pp);
 222                         }
 223                 }
 224
 225                 p->p_oppid = 0;
 226                 p->p_flags &= ~P_WAITED;        /* XXX ? */
 227                 wakeup((caddr_t) curp);         /* XXX for CTL_WAIT below ? */
 228
 229                 break;
 230
 231         /*
 232          * Step.  Let the target process execute a single instruction.
 233          */
 234         case PROCFS_CTL_STEP:
 235                 LWPHOLD(lp);
 236                 error = procfs_sstep(lp);
 237                 LWPRELE(lp);
 238                 if (error)
 239                         return (error);
 240                 break;
 241
 242         /*
 243          * Run.  Let the target process continue running until a breakpoint
 244          * or some other trap.
 245          */
 246         case PROCFS_CTL_RUN:
 247                 break;
 248
 249         /*
 250          * Wait for the target process to stop.
 251          * If the target is not being traced then just wait
 252          * to enter
 253          */
 254         case PROCFS_CTL_WAIT:
 255                 error = 0;
 256                 if (p->p_flags & P_TRACED) {
 257                         while (error == 0 &&
 258                                         p->p_stat != SSTOP &&
 259                                         (p->p_flags & P_TRACED) &&
 260                                         (p->p_pptr == curp)) {
 261                                 error = tsleep((caddr_t) p,
 262                                                 PCATCH, "procfsx", 0);
 263                         }
 264                         if (error == 0 && !TRACE_WAIT_P(curp, p))
 265                                 error = EBUSY;
 266                 } else {
 267                         while (error == 0 && p->p_stat != SSTOP) {
 268                                 error = tsleep((caddr_t) p,
 269                                                 PCATCH, "procfs", 0);
 270                         }
 271                 }
 272                 return (error);
 273
 274         default:
 275                 panic("procfs_control");
 276         }
 277
 278         /*
 279          * If the process is in a stopped state, make it runnable again.
 280          * Do not set LWP_MP_BREAKTSLEEP - that is, do not break a tsleep
 281          * that might be in progress.
 282          */
 283         if (p->p_stat == SSTOP)
 284                 proc_unstop(p, SSTOP);
 285         return (0);
 286 }
 287
 288 int
 289 procfs_doctl(struct proc *curp, struct lwp *lp, struct pfsnode *pfs,
 290              struct uio *uio)
 291 {
 292         struct proc *p = lp->lwp_proc;
 293         int xlen;
 294         int error;
 295         char msg[PROCFS_CTLLEN+1];
 296         vfs_namemap_t *nm;
 297
 298         ASSERT_LWKT_TOKEN_HELD(&p->p_token);
 299
 300         if (uio->uio_rw != UIO_WRITE)
 301                 return (EOPNOTSUPP);
 302
 303         xlen = PROCFS_CTLLEN;
 304         error = vfs_getuserstr(uio, msg, &xlen);
 305         if (error)
 306                 return (error);
 307
 308         /*
 309          * Map signal names into signal generation
 310          * or debug control.  Unknown commands and/or signals
 311          * return EOPNOTSUPP.
 312          *
 313          * Sending a signal while the process is being debugged
 314          * also has the side effect of letting the target continue
 315          * to run.  There is no way to single-step a signal delivery.
 316          */
 317         error = EOPNOTSUPP;
 318
 319         nm = vfs_findname(ctlnames, msg, xlen);
 320         if (nm) {
 321                 error = procfs_control(curp, lp, nm->nm_val);
 322         } else {
 323                 nm = vfs_findname(signames, msg, xlen);
 324                 if (nm) {
 325                         if (TRACE_WAIT_P(curp, p)) {
 326                                 p->p_xstat = nm->nm_val;
 327 #ifdef FIX_SSTEP
 328                                 FIX_SSTEP(lp);
 329 #endif
 330                                 /*
 331                                  * Make the process runnable but do not
 332                                  * break its tsleep.
 333                                  */
 334                                 proc_unstop(p, SSTOP);
 335                         } else {
 336                                 ksignal(p, nm->nm_val);
 337                         }
 338                         error = 0;
 339                 }
 340         }
 341
 342         return (error);
 343 }