kern_ktrace.c

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    1 /*-
    2  * Copyright (c) 1989, 1993
    3  *      The Regents of the University of California.
    4  * Copyright (c) 2005 Robert N. M. Watson
    5  * All rights reserved.
    6  *
    7  * Redistribution and use in source and binary forms, with or without
    8  * modification, are permitted provided that the following conditions
    9  * are met:
   10  * 1. Redistributions of source code must retain the above copyright
   11  *    notice, this list of conditions and the following disclaimer.
   12  * 2. Redistributions in binary form must reproduce the above copyright
   13  *    notice, this list of conditions and the following disclaimer in the
   14  *    documentation and/or other materials provided with the distribution.
   15  * 4. Neither the name of the University nor the names of its contributors
   16  *    may be used to endorse or promote products derived from this software
   17  *    without specific prior written permission.
   18  *
   19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   29  * SUCH DAMAGE.
   30  *
   31  *      @(#)kern_ktrace.c       8.2 (Berkeley) 9/23/93
   32  */
   33 
   34 #include <sys/cdefs.h>
   35 __FBSDID("$FreeBSD$");
   36 
   37 #include "opt_ktrace.h"
   38 #include "opt_mac.h"
   39 
   40 #include <sys/param.h>
   41 #include <sys/systm.h>
   42 #include <sys/fcntl.h>
   43 #include <sys/kernel.h>
   44 #include <sys/kthread.h>
   45 #include <sys/lock.h>
   46 #include <sys/mutex.h>
   47 #include <sys/malloc.h>
   48 #include <sys/mount.h>
   49 #include <sys/namei.h>
   50 #include <sys/priv.h>
   51 #include <sys/proc.h>
   52 #include <sys/unistd.h>
   53 #include <sys/vnode.h>
   54 #include <sys/socket.h>
   55 #include <sys/stat.h>
   56 #include <sys/ktrace.h>
   57 #include <sys/sx.h>
   58 #include <sys/sysctl.h>
   59 #include <sys/syslog.h>
   60 #include <sys/sysproto.h>
   61 
   62 #include <security/mac/mac_framework.h>
   63 
   64 /*
   65  * The ktrace facility allows the tracing of certain key events in user space
   66  * processes, such as system calls, signal delivery, context switches, and
   67  * user generated events using utrace(2).  It works by streaming event
   68  * records and data to a vnode associated with the process using the
   69  * ktrace(2) system call.  In general, records can be written directly from
   70  * the context that generates the event.  One important exception to this is
   71  * during a context switch, where sleeping is not permitted.  To handle this
   72  * case, trace events are generated using in-kernel ktr_request records, and
   73  * then delivered to disk at a convenient moment -- either immediately, the
   74  * next traceable event, at system call return, or at process exit.
   75  *
   76  * When dealing with multiple threads or processes writing to the same event
   77  * log, ordering guarantees are weak: specifically, if an event has multiple
   78  * records (i.e., system call enter and return), they may be interlaced with
   79  * records from another event.  Process and thread ID information is provided
   80  * in the record, and user applications can de-interlace events if required.
   81  */
   82 
   83 static MALLOC_DEFINE(M_KTRACE, "KTRACE", "KTRACE");
   84 
   85 #ifdef KTRACE
   86 
   87 #ifndef KTRACE_REQUEST_POOL
   88 #define KTRACE_REQUEST_POOL     100
   89 #endif
   90 
   91 struct ktr_request {
   92         struct  ktr_header ktr_header;
   93         void    *ktr_buffer;
   94         union {
   95                 struct  ktr_syscall ktr_syscall;
   96                 struct  ktr_sysret ktr_sysret;
   97                 struct  ktr_genio ktr_genio;
   98                 struct  ktr_psig ktr_psig;
   99                 struct  ktr_csw ktr_csw;
  100         } ktr_data;
  101         STAILQ_ENTRY(ktr_request) ktr_list;
  102 };
  103 
  104 static int data_lengths[] = {
  105         0,                                      /* none */
  106         offsetof(struct ktr_syscall, ktr_args), /* KTR_SYSCALL */
  107         sizeof(struct ktr_sysret),              /* KTR_SYSRET */
  108         0,                                      /* KTR_NAMEI */
  109         sizeof(struct ktr_genio),               /* KTR_GENIO */
  110         sizeof(struct ktr_psig),                /* KTR_PSIG */
  111         sizeof(struct ktr_csw),                 /* KTR_CSW */
  112         0,                                      /* KTR_USER */
  113         0,                                      /* KTR_STRUCT */
  114 };
  115 
  116 static STAILQ_HEAD(, ktr_request) ktr_free;
  117 
  118 static SYSCTL_NODE(_kern, OID_AUTO, ktrace, CTLFLAG_RD, 0, "KTRACE options");
  119 
  120 static u_int ktr_requestpool = KTRACE_REQUEST_POOL;
  121 TUNABLE_INT("kern.ktrace.request_pool", &ktr_requestpool);
  122 
  123 static u_int ktr_geniosize = PAGE_SIZE;
  124 TUNABLE_INT("kern.ktrace.genio_size", &ktr_geniosize);
  125 SYSCTL_UINT(_kern_ktrace, OID_AUTO, genio_size, CTLFLAG_RW, &ktr_geniosize,
  126     0, "Maximum size of genio event payload");
  127 
  128 static int print_message = 1;
  129 struct mtx ktrace_mtx;
  130 static struct sx ktrace_sx;
  131 
  132 static void ktrace_init(void *dummy);
  133 static int sysctl_kern_ktrace_request_pool(SYSCTL_HANDLER_ARGS);
  134 static u_int ktrace_resize_pool(u_int newsize);
  135 static struct ktr_request *ktr_getrequest(int type);
  136 static void ktr_submitrequest(struct thread *td, struct ktr_request *req);
  137 static void ktr_freerequest(struct ktr_request *req);
  138 static void ktr_writerequest(struct thread *td, struct ktr_request *req);
  139 static int ktrcanset(struct thread *,struct proc *);
  140 static int ktrsetchildren(struct thread *,struct proc *,int,int,struct vnode *);
  141 static int ktrops(struct thread *,struct proc *,int,int,struct vnode *);
  142 
  143 /*
  144  * ktrace itself generates events, such as context switches, which we do not
  145  * wish to trace.  Maintain a flag, TDP_INKTRACE, on each thread to determine
  146  * whether or not it is in a region where tracing of events should be
  147  * suppressed.
  148  */
  149 static void
  150 ktrace_enter(struct thread *td)
  151 {
  152 
  153         KASSERT(!(td->td_pflags & TDP_INKTRACE), ("ktrace_enter: flag set"));
  154         td->td_pflags |= TDP_INKTRACE;
  155 }
  156 
  157 static void
  158 ktrace_exit(struct thread *td)
  159 {
  160 
  161         KASSERT(td->td_pflags & TDP_INKTRACE, ("ktrace_exit: flag not set"));
  162         td->td_pflags &= ~TDP_INKTRACE;
  163 }
  164 
  165 static void
  166 ktrace_assert(struct thread *td)
  167 {
  168 
  169         KASSERT(td->td_pflags & TDP_INKTRACE, ("ktrace_assert: flag not set"));
  170 }
  171 
  172 static void
  173 ktrace_init(void *dummy)
  174 {
  175         struct ktr_request *req;
  176         int i;
  177 
  178         mtx_init(&ktrace_mtx, "ktrace", NULL, MTX_DEF | MTX_QUIET);
  179         sx_init(&ktrace_sx, "ktrace_sx");
  180         STAILQ_INIT(&ktr_free);
  181         for (i = 0; i < ktr_requestpool; i++) {
  182                 req = malloc(sizeof(struct ktr_request), M_KTRACE, M_WAITOK);
  183                 STAILQ_INSERT_HEAD(&ktr_free, req, ktr_list);
  184         }
  185 }
  186 SYSINIT(ktrace_init, SI_SUB_KTRACE, SI_ORDER_ANY, ktrace_init, NULL);
  187 
  188 static int
  189 sysctl_kern_ktrace_request_pool(SYSCTL_HANDLER_ARGS)
  190 {
  191         struct thread *td;
  192         u_int newsize, oldsize, wantsize;
  193         int error;
  194 
  195         /* Handle easy read-only case first to avoid warnings from GCC. */
  196         if (!req->newptr) {
  197                 mtx_lock(&ktrace_mtx);
  198                 oldsize = ktr_requestpool;
  199                 mtx_unlock(&ktrace_mtx);
  200                 return (SYSCTL_OUT(req, &oldsize, sizeof(u_int)));
  201         }
  202 
  203         error = SYSCTL_IN(req, &wantsize, sizeof(u_int));
  204         if (error)
  205                 return (error);
  206         td = curthread;
  207         ktrace_enter(td);
  208         mtx_lock(&ktrace_mtx);
  209         oldsize = ktr_requestpool;
  210         newsize = ktrace_resize_pool(wantsize);
  211         mtx_unlock(&ktrace_mtx);
  212         ktrace_exit(td);
  213         error = SYSCTL_OUT(req, &oldsize, sizeof(u_int));
  214         if (error)
  215                 return (error);
  216         if (wantsize > oldsize && newsize < wantsize)
  217                 return (ENOSPC);
  218         return (0);
  219 }
  220 SYSCTL_PROC(_kern_ktrace, OID_AUTO, request_pool, CTLTYPE_UINT|CTLFLAG_RW,
  221     &ktr_requestpool, 0, sysctl_kern_ktrace_request_pool, "IU", "");
  222 
  223 static u_int
  224 ktrace_resize_pool(u_int newsize)
  225 {
  226         struct ktr_request *req;
  227         int bound;
  228 
  229         mtx_assert(&ktrace_mtx, MA_OWNED);
  230         print_message = 1;
  231         bound = newsize - ktr_requestpool;
  232         if (bound == 0)
  233                 return (ktr_requestpool);
  234         if (bound < 0)
  235                 /* Shrink pool down to newsize if possible. */
  236                 while (bound++ < 0) {
  237                         req = STAILQ_FIRST(&ktr_free);
  238                         if (req == NULL)
  239                                 return (ktr_requestpool);
  240                         STAILQ_REMOVE_HEAD(&ktr_free, ktr_list);
  241                         ktr_requestpool--;
  242                         mtx_unlock(&ktrace_mtx);
  243                         free(req, M_KTRACE);
  244                         mtx_lock(&ktrace_mtx);
  245                 }
  246         else
  247                 /* Grow pool up to newsize. */
  248                 while (bound-- > 0) {
  249                         mtx_unlock(&ktrace_mtx);
  250                         req = malloc(sizeof(struct ktr_request), M_KTRACE,
  251                             M_WAITOK);
  252                         mtx_lock(&ktrace_mtx);
  253                         STAILQ_INSERT_HEAD(&ktr_free, req, ktr_list);
  254                         ktr_requestpool++;
  255                 }
  256         return (ktr_requestpool);
  257 }
  258 
  259 static struct ktr_request *
  260 ktr_getrequest(int type)
  261 {
  262         struct ktr_request *req;
  263         struct thread *td = curthread;
  264         struct proc *p = td->td_proc;
  265         int pm;
  266 
  267         ktrace_enter(td);       /* XXX: In caller instead? */
  268         mtx_lock(&ktrace_mtx);
  269         if (!KTRCHECK(td, type)) {
  270                 mtx_unlock(&ktrace_mtx);
  271                 ktrace_exit(td);
  272                 return (NULL);
  273         }
  274         req = STAILQ_FIRST(&ktr_free);
  275         if (req != NULL) {
  276                 STAILQ_REMOVE_HEAD(&ktr_free, ktr_list);
  277                 req->ktr_header.ktr_type = type;
  278                 if (p->p_traceflag & KTRFAC_DROP) {
  279                         req->ktr_header.ktr_type |= KTR_DROP;
  280                         p->p_traceflag &= ~KTRFAC_DROP;
  281                 }
  282                 mtx_unlock(&ktrace_mtx);
  283                 microtime(&req->ktr_header.ktr_time);
  284                 req->ktr_header.ktr_pid = p->p_pid;
  285                 req->ktr_header.ktr_tid = td->td_tid;
  286                 bcopy(p->p_comm, req->ktr_header.ktr_comm, MAXCOMLEN + 1);
  287                 req->ktr_buffer = NULL;
  288                 req->ktr_header.ktr_len = 0;
  289         } else {
  290                 p->p_traceflag |= KTRFAC_DROP;
  291                 pm = print_message;
  292                 print_message = 0;
  293                 mtx_unlock(&ktrace_mtx);
  294                 if (pm)
  295                         printf("Out of ktrace request objects.\n");
  296                 ktrace_exit(td);
  297         }
  298         return (req);
  299 }
  300 
  301 /*
  302  * Some trace generation environments don't permit direct access to VFS,
  303  * such as during a context switch where sleeping is not allowed.  Under these
  304  * circumstances, queue a request to the thread to be written asynchronously
  305  * later.
  306  */
  307 static void
  308 ktr_enqueuerequest(struct thread *td, struct ktr_request *req)
  309 {
  310 
  311         mtx_lock(&ktrace_mtx);
  312         STAILQ_INSERT_TAIL(&td->td_proc->p_ktr, req, ktr_list);
  313         mtx_unlock(&ktrace_mtx);
  314         ktrace_exit(td);
  315 }
  316 
  317 /*
  318  * Drain any pending ktrace records from the per-thread queue to disk.  This
  319  * is used both internally before committing other records, and also on
  320  * system call return.  We drain all the ones we can find at the time when
  321  * drain is requested, but don't keep draining after that as those events
  322  * may me approximately "after" the current event.
  323  */
  324 static void
  325 ktr_drain(struct thread *td)
  326 {
  327         struct ktr_request *queued_req;
  328         STAILQ_HEAD(, ktr_request) local_queue;
  329 
  330         ktrace_assert(td);
  331         sx_assert(&ktrace_sx, SX_XLOCKED);
  332 
  333         STAILQ_INIT(&local_queue);      /* XXXRW: needed? */
  334 
  335         if (!STAILQ_EMPTY(&td->td_proc->p_ktr)) {
  336                 mtx_lock(&ktrace_mtx);
  337                 STAILQ_CONCAT(&local_queue, &td->td_proc->p_ktr);
  338                 mtx_unlock(&ktrace_mtx);
  339 
  340                 while ((queued_req = STAILQ_FIRST(&local_queue))) {
  341                         STAILQ_REMOVE_HEAD(&local_queue, ktr_list);
  342                         ktr_writerequest(td, queued_req);
  343                         ktr_freerequest(queued_req);
  344                 }
  345         }
  346 }
  347 
  348 /*
  349  * Submit a trace record for immediate commit to disk -- to be used only
  350  * where entering VFS is OK.  First drain any pending records that may have
  351  * been cached in the thread.
  352  */
  353 static void
  354 ktr_submitrequest(struct thread *td, struct ktr_request *req)
  355 {
  356 
  357         ktrace_assert(td);
  358 
  359         sx_xlock(&ktrace_sx);
  360         ktr_drain(td);
  361         ktr_writerequest(td, req);
  362         ktr_freerequest(req);
  363         sx_xunlock(&ktrace_sx);
  364 
  365         ktrace_exit(td);
  366 }
  367 
  368 static void
  369 ktr_freerequest(struct ktr_request *req)
  370 {
  371 
  372         if (req->ktr_buffer != NULL)
  373                 free(req->ktr_buffer, M_KTRACE);
  374         mtx_lock(&ktrace_mtx);
  375         STAILQ_INSERT_HEAD(&ktr_free, req, ktr_list);
  376         mtx_unlock(&ktrace_mtx);
  377 }
  378 
  379 void
  380 ktrsyscall(code, narg, args)
  381         int code, narg;
  382         register_t args[];
  383 {
  384         struct ktr_request *req;
  385         struct ktr_syscall *ktp;
  386         size_t buflen;
  387         char *buf = NULL;
  388 
  389         buflen = sizeof(register_t) * narg;
  390         if (buflen > 0) {
  391                 buf = malloc(buflen, M_KTRACE, M_WAITOK);
  392                 bcopy(args, buf, buflen);
  393         }
  394         req = ktr_getrequest(KTR_SYSCALL);
  395         if (req == NULL) {
  396                 if (buf != NULL)
  397                         free(buf, M_KTRACE);
  398                 return;
  399         }
  400         ktp = &req->ktr_data.ktr_syscall;
  401         ktp->ktr_code = code;
  402         ktp->ktr_narg = narg;
  403         if (buflen > 0) {
  404                 req->ktr_header.ktr_len = buflen;
  405                 req->ktr_buffer = buf;
  406         }
  407         ktr_submitrequest(curthread, req);
  408 }
  409 
  410 void
  411 ktrsysret(code, error, retval)
  412         int code, error;
  413         register_t retval;
  414 {
  415         struct ktr_request *req;
  416         struct ktr_sysret *ktp;
  417 
  418         req = ktr_getrequest(KTR_SYSRET);
  419         if (req == NULL)
  420                 return;
  421         ktp = &req->ktr_data.ktr_sysret;
  422         ktp->ktr_code = code;
  423         ktp->ktr_error = error;
  424         ktp->ktr_retval = retval;               /* what about val2 ? */
  425         ktr_submitrequest(curthread, req);
  426 }
  427 
  428 /*
  429  * When a process exits, drain per-process asynchronous trace records.
  430  */
  431 void
  432 ktrprocexit(struct thread *td)
  433 {
  434 
  435         ktrace_enter(td);
  436         sx_xlock(&ktrace_sx);
  437         ktr_drain(td);
  438         sx_xunlock(&ktrace_sx);
  439         ktrace_exit(td);
  440 }
  441 
  442 /*
  443  * When a thread returns, drain any asynchronous records generated by the
  444  * system call.
  445  */
  446 void
  447 ktruserret(struct thread *td)
  448 {
  449 
  450         ktrace_enter(td);
  451         sx_xlock(&ktrace_sx);
  452         ktr_drain(td);
  453         sx_xunlock(&ktrace_sx);
  454         ktrace_exit(td);
  455 }
  456 
  457 void
  458 ktrnamei(path)
  459         char *path;
  460 {
  461         struct ktr_request *req;
  462         int namelen;
  463         char *buf = NULL;
  464 
  465         namelen = strlen(path);
  466         if (namelen > 0) {
  467                 buf = malloc(namelen, M_KTRACE, M_WAITOK);
  468                 bcopy(path, buf, namelen);
  469         }
  470         req = ktr_getrequest(KTR_NAMEI);
  471         if (req == NULL) {
  472                 if (buf != NULL)
  473                         free(buf, M_KTRACE);
  474                 return;
  475         }
  476         if (namelen > 0) {
  477                 req->ktr_header.ktr_len = namelen;
  478                 req->ktr_buffer = buf;
  479         }
  480         ktr_submitrequest(curthread, req);
  481 }
  482 
  483 void
  484 ktrgenio(fd, rw, uio, error)
  485         int fd;
  486         enum uio_rw rw;
  487         struct uio *uio;
  488         int error;
  489 {
  490         struct ktr_request *req;
  491         struct ktr_genio *ktg;
  492         int datalen;
  493         char *buf;
  494 
  495         if (error) {
  496                 free(uio, M_IOV);
  497                 return;
  498         }
  499         uio->uio_offset = 0;
  500         uio->uio_rw = UIO_WRITE;
  501         datalen = imin(uio->uio_resid, ktr_geniosize);
  502         buf = malloc(datalen, M_KTRACE, M_WAITOK);
  503         error = uiomove(buf, datalen, uio);
  504         free(uio, M_IOV);
  505         if (error) {
  506                 free(buf, M_KTRACE);
  507                 return;
  508         }
  509         req = ktr_getrequest(KTR_GENIO);
  510         if (req == NULL) {
  511                 free(buf, M_KTRACE);
  512                 return;
  513         }
  514         ktg = &req->ktr_data.ktr_genio;
  515         ktg->ktr_fd = fd;
  516         ktg->ktr_rw = rw;
  517         req->ktr_header.ktr_len = datalen;
  518         req->ktr_buffer = buf;
  519         ktr_submitrequest(curthread, req);
  520 }
  521 
  522 void
  523 ktrpsig(sig, action, mask, code)
  524         int sig;
  525         sig_t action;
  526         sigset_t *mask;
  527         int code;
  528 {
  529         struct ktr_request *req;
  530         struct ktr_psig *kp;
  531 
  532         req = ktr_getrequest(KTR_PSIG);
  533         if (req == NULL)
  534                 return;
  535         kp = &req->ktr_data.ktr_psig;
  536         kp->signo = (char)sig;
  537         kp->action = action;
  538         kp->mask = *mask;
  539         kp->code = code;
  540         ktr_enqueuerequest(curthread, req);
  541 }
  542 
  543 void
  544 ktrcsw(out, user)
  545         int out, user;
  546 {
  547         struct ktr_request *req;
  548         struct ktr_csw *kc;
  549 
  550         req = ktr_getrequest(KTR_CSW);
  551         if (req == NULL)
  552                 return;
  553         kc = &req->ktr_data.ktr_csw;
  554         kc->out = out;
  555         kc->user = user;
  556         ktr_enqueuerequest(curthread, req);
  557 }
  558 
  559 void
  560 ktrstruct(name, namelen, data, datalen)
  561         const char *name;
  562         size_t namelen;
  563         void *data;
  564         size_t datalen;
  565 {
  566         struct ktr_request *req;
  567         char *buf = NULL;
  568         size_t buflen;
  569 
  570         if (!data)
  571                 datalen = 0;
  572         buflen = namelen + 1 + datalen;
  573         buf = malloc(buflen, M_KTRACE, M_WAITOK);
  574         bcopy(name, buf, namelen);
  575         buf[namelen] = '\0';
  576         bcopy(data, buf + namelen + 1, datalen);
  577         if ((req = ktr_getrequest(KTR_STRUCT)) == NULL) {
  578                 free(buf, M_KTRACE);
  579                 return;
  580         }
  581         req->ktr_buffer = buf;
  582         req->ktr_header.ktr_len = buflen;
  583         ktr_submitrequest(curthread, req);
  584 }
  585 #endif /* KTRACE */
  586 
  587 /* Interface and common routines */
  588 
  589 #ifndef _SYS_SYSPROTO_H_
  590 struct ktrace_args {
  591         char    *fname;
  592         int     ops;
  593         int     facs;
  594         int     pid;
  595 };
  596 #endif
  597 /* ARGSUSED */
  598 int
  599 ktrace(td, uap)
  600         struct thread *td;
  601         register struct ktrace_args *uap;
  602 {
  603 #ifdef KTRACE
  604         register struct vnode *vp = NULL;
  605         register struct proc *p;
  606         struct pgrp *pg;
  607         int facs = uap->facs & ~KTRFAC_ROOT;
  608         int ops = KTROP(uap->ops);
  609         int descend = uap->ops & KTRFLAG_DESCEND;
  610         int nfound, ret = 0;
  611         int flags, error = 0, vfslocked;
  612         struct nameidata nd;
  613         struct ucred *cred;
  614 
  615         /*
  616          * Need something to (un)trace.
  617          */
  618         if (ops != KTROP_CLEARFILE && facs == 0)
  619                 return (EINVAL);
  620 
  621         ktrace_enter(td);
  622         if (ops != KTROP_CLEAR) {
  623                 /*
  624                  * an operation which requires a file argument.
  625                  */
  626                 NDINIT(&nd, LOOKUP, NOFOLLOW | MPSAFE, UIO_USERSPACE,
  627                     uap->fname, td);
  628                 flags = FREAD | FWRITE | O_NOFOLLOW;
  629                 error = vn_open(&nd, &flags, 0, NULL);
  630                 if (error) {
  631                         ktrace_exit(td);
  632                         return (error);
  633                 }
  634                 vfslocked = NDHASGIANT(&nd);
  635                 NDFREE(&nd, NDF_ONLY_PNBUF);
  636                 vp = nd.ni_vp;
  637                 VOP_UNLOCK(vp, 0, td);
  638                 if (vp->v_type != VREG) {
  639                         (void) vn_close(vp, FREAD|FWRITE, td->td_ucred, td);
  640                         VFS_UNLOCK_GIANT(vfslocked);
  641                         ktrace_exit(td);
  642                         return (EACCES);
  643                 }
  644                 VFS_UNLOCK_GIANT(vfslocked);
  645         }
  646         /*
  647          * Clear all uses of the tracefile.
  648          */
  649         if (ops == KTROP_CLEARFILE) {
  650                 int vrele_count;
  651 
  652                 vrele_count = 0;
  653                 sx_slock(&allproc_lock);
  654                 FOREACH_PROC_IN_SYSTEM(p) {
  655                         PROC_LOCK(p);
  656                         if (p->p_tracevp == vp) {
  657                                 if (ktrcanset(td, p)) {
  658                                         mtx_lock(&ktrace_mtx);
  659                                         cred = p->p_tracecred;
  660                                         p->p_tracecred = NULL;
  661                                         p->p_tracevp = NULL;
  662                                         p->p_traceflag = 0;
  663                                         mtx_unlock(&ktrace_mtx);
  664                                         vrele_count++;
  665                                         crfree(cred);
  666                                 } else
  667                                         error = EPERM;
  668                         }
  669                         PROC_UNLOCK(p);
  670                 }
  671                 sx_sunlock(&allproc_lock);
  672                 if (vrele_count > 0) {
  673                         vfslocked = VFS_LOCK_GIANT(vp->v_mount);
  674                         while (vrele_count-- > 0)
  675                                 vrele(vp);
  676                         VFS_UNLOCK_GIANT(vfslocked);
  677                 }
  678                 goto done;
  679         }
  680         /*
  681          * do it
  682          */
  683         sx_slock(&proctree_lock);
  684         if (uap->pid < 0) {
  685                 /*
  686                  * by process group
  687                  */
  688                 pg = pgfind(-uap->pid);
  689                 if (pg == NULL) {
  690                         sx_sunlock(&proctree_lock);
  691                         error = ESRCH;
  692                         goto done;
  693                 }
  694                 /*
  695                  * ktrops() may call vrele(). Lock pg_members
  696                  * by the proctree_lock rather than pg_mtx.
  697                  */
  698                 PGRP_UNLOCK(pg);
  699                 nfound = 0;
  700                 LIST_FOREACH(p, &pg->pg_members, p_pglist) {
  701                         PROC_LOCK(p);
  702                         if (p_cansee(td, p) != 0) {
  703                                 PROC_UNLOCK(p); 
  704                                 continue;
  705                         }
  706                         PROC_UNLOCK(p); 
  707                         nfound++;
  708                         if (descend)
  709                                 ret |= ktrsetchildren(td, p, ops, facs, vp);
  710                         else
  711                                 ret |= ktrops(td, p, ops, facs, vp);
  712                 }
  713                 if (nfound == 0) {
  714                         sx_sunlock(&proctree_lock);
  715                         error = ESRCH;
  716                         goto done;
  717                 }
  718         } else {
  719                 /*
  720                  * by pid
  721                  */
  722                 p = pfind(uap->pid);
  723                 if (p == NULL) {
  724                         sx_sunlock(&proctree_lock);
  725                         error = ESRCH;
  726                         goto done;
  727                 }
  728                 error = p_cansee(td, p);
  729                 /*
  730                  * The slock of the proctree lock will keep this process
  731                  * from going away, so unlocking the proc here is ok.
  732                  */
  733                 PROC_UNLOCK(p);
  734                 if (error) {
  735                         sx_sunlock(&proctree_lock);
  736                         goto done;
  737                 }
  738                 if (descend)
  739                         ret |= ktrsetchildren(td, p, ops, facs, vp);
  740                 else
  741                         ret |= ktrops(td, p, ops, facs, vp);
  742         }
  743         sx_sunlock(&proctree_lock);
  744         if (!ret)
  745                 error = EPERM;
  746 done:
  747         if (vp != NULL) {
  748                 vfslocked = VFS_LOCK_GIANT(vp->v_mount);
  749                 (void) vn_close(vp, FWRITE, td->td_ucred, td);
  750                 VFS_UNLOCK_GIANT(vfslocked);
  751         }
  752         ktrace_exit(td);
  753         return (error);
  754 #else /* !KTRACE */
  755         return (ENOSYS);
  756 #endif /* KTRACE */
  757 }
  758 
  759 /* ARGSUSED */
  760 int
  761 utrace(td, uap)
  762         struct thread *td;
  763         register struct utrace_args *uap;
  764 {
  765 
  766 #ifdef KTRACE
  767         struct ktr_request *req;
  768         void *cp;
  769         int error;
  770 
  771         if (!KTRPOINT(td, KTR_USER))
  772                 return (0);
  773         if (uap->len > KTR_USER_MAXLEN)
  774                 return (EINVAL);
  775         cp = malloc(uap->len, M_KTRACE, M_WAITOK);
  776         error = copyin(uap->addr, cp, uap->len);
  777         if (error) {
  778                 free(cp, M_KTRACE);
  779                 return (error);
  780         }
  781         req = ktr_getrequest(KTR_USER);
  782         if (req == NULL) {
  783                 free(cp, M_KTRACE);
  784                 return (ENOMEM);
  785         }
  786         req->ktr_buffer = cp;
  787         req->ktr_header.ktr_len = uap->len;
  788         ktr_submitrequest(td, req);
  789         return (0);
  790 #else /* !KTRACE */
  791         return (ENOSYS);
  792 #endif /* KTRACE */
  793 }
  794 
  795 #ifdef KTRACE
  796 static int
  797 ktrops(td, p, ops, facs, vp)
  798         struct thread *td;
  799         struct proc *p;
  800         int ops, facs;
  801         struct vnode *vp;
  802 {
  803         struct vnode *tracevp = NULL;
  804         struct ucred *tracecred = NULL;
  805 
  806         PROC_LOCK(p);
  807         if (!ktrcanset(td, p)) {
  808                 PROC_UNLOCK(p);
  809                 return (0);
  810         }
  811         mtx_lock(&ktrace_mtx);
  812         if (ops == KTROP_SET) {
  813                 if (p->p_tracevp != vp) {
  814                         /*
  815                          * if trace file already in use, relinquish below
  816                          */
  817                         tracevp = p->p_tracevp;
  818                         VREF(vp);
  819                         p->p_tracevp = vp;
  820                 }
  821                 if (p->p_tracecred != td->td_ucred) {
  822                         tracecred = p->p_tracecred;
  823                         p->p_tracecred = crhold(td->td_ucred);
  824                 }
  825                 p->p_traceflag |= facs;
  826                 if (priv_check(td, PRIV_KTRACE) == 0)
  827                         p->p_traceflag |= KTRFAC_ROOT;
  828         } else {
  829                 /* KTROP_CLEAR */
  830                 if (((p->p_traceflag &= ~facs) & KTRFAC_MASK) == 0) {
  831                         /* no more tracing */
  832                         p->p_traceflag = 0;
  833                         tracevp = p->p_tracevp;
  834                         p->p_tracevp = NULL;
  835                         tracecred = p->p_tracecred;
  836                         p->p_tracecred = NULL;
  837                 }
  838         }
  839         mtx_unlock(&ktrace_mtx);
  840         PROC_UNLOCK(p);
  841         if (tracevp != NULL) {
  842                 int vfslocked;
  843 
  844                 vfslocked = VFS_LOCK_GIANT(tracevp->v_mount);
  845                 vrele(tracevp);
  846                 VFS_UNLOCK_GIANT(vfslocked);
  847         }
  848         if (tracecred != NULL)
  849                 crfree(tracecred);
  850 
  851         return (1);
  852 }
  853 
  854 static int
  855 ktrsetchildren(td, top, ops, facs, vp)
  856         struct thread *td;
  857         struct proc *top;
  858         int ops, facs;
  859         struct vnode *vp;
  860 {
  861         register struct proc *p;
  862         register int ret = 0;
  863 
  864         p = top;
  865         sx_assert(&proctree_lock, SX_LOCKED);
  866         for (;;) {
  867                 ret |= ktrops(td, p, ops, facs, vp);
  868                 /*
  869                  * If this process has children, descend to them next,
  870                  * otherwise do any siblings, and if done with this level,
  871                  * follow back up the tree (but not past top).
  872                  */
  873                 if (!LIST_EMPTY(&p->p_children))
  874                         p = LIST_FIRST(&p->p_children);
  875                 else for (;;) {
  876                         if (p == top)
  877                                 return (ret);
  878                         if (LIST_NEXT(p, p_sibling)) {
  879                                 p = LIST_NEXT(p, p_sibling);
  880                                 break;
  881                         }
  882                         p = p->p_pptr;
  883                 }
  884         }
  885         /*NOTREACHED*/
  886 }
  887 
  888 static void
  889 ktr_writerequest(struct thread *td, struct ktr_request *req)
  890 {
  891         struct ktr_header *kth;
  892         struct vnode *vp;
  893         struct proc *p;
  894         struct ucred *cred;
  895         struct uio auio;
  896         struct iovec aiov[3];
  897         struct mount *mp;
  898         int datalen, buflen, vrele_count;
  899         int error, vfslocked;
  900 
  901         /*
  902          * We hold the vnode and credential for use in I/O in case ktrace is
  903          * disabled on the process as we write out the request.
  904          *
  905          * XXXRW: This is not ideal: we could end up performing a write after
  906          * the vnode has been closed.
  907          */
  908         mtx_lock(&ktrace_mtx);
  909         vp = td->td_proc->p_tracevp;
  910         if (vp != NULL)
  911                 VREF(vp);
  912         cred = td->td_proc->p_tracecred;
  913         if (cred != NULL)
  914                 crhold(cred);
  915         mtx_unlock(&ktrace_mtx);
  916 
  917         /*
  918          * If vp is NULL, the vp has been cleared out from under this
  919          * request, so just drop it.  Make sure the credential and vnode are
  920          * in sync: we should have both or neither.
  921          */
  922         if (vp == NULL) {
  923                 KASSERT(cred == NULL, ("ktr_writerequest: cred != NULL"));
  924                 return;
  925         }
  926         KASSERT(cred != NULL, ("ktr_writerequest: cred == NULL"));
  927 
  928         kth = &req->ktr_header;
  929         datalen = data_lengths[(u_short)kth->ktr_type & ~KTR_DROP];
  930         buflen = kth->ktr_len;
  931         auio.uio_iov = &aiov[0];
  932         auio.uio_offset = 0;
  933         auio.uio_segflg = UIO_SYSSPACE;
  934         auio.uio_rw = UIO_WRITE;
  935         aiov[0].iov_base = (caddr_t)kth;
  936         aiov[0].iov_len = sizeof(struct ktr_header);
  937         auio.uio_resid = sizeof(struct ktr_header);
  938         auio.uio_iovcnt = 1;
  939         auio.uio_td = td;
  940         if (datalen != 0) {
  941                 aiov[1].iov_base = (caddr_t)&req->ktr_data;
  942                 aiov[1].iov_len = datalen;
  943                 auio.uio_resid += datalen;
  944                 auio.uio_iovcnt++;
  945                 kth->ktr_len += datalen;
  946         }
  947         if (buflen != 0) {
  948                 KASSERT(req->ktr_buffer != NULL, ("ktrace: nothing to write"));
  949                 aiov[auio.uio_iovcnt].iov_base = req->ktr_buffer;
  950                 aiov[auio.uio_iovcnt].iov_len = buflen;
  951                 auio.uio_resid += buflen;
  952                 auio.uio_iovcnt++;
  953         }
  954 
  955         vfslocked = VFS_LOCK_GIANT(vp->v_mount);
  956         vn_start_write(vp, &mp, V_WAIT);
  957         vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
  958         (void)VOP_LEASE(vp, td, cred, LEASE_WRITE);
  959 #ifdef MAC
  960         error = mac_check_vnode_write(cred, NOCRED, vp);
  961         if (error == 0)
  962 #endif
  963                 error = VOP_WRITE(vp, &auio, IO_UNIT | IO_APPEND, cred);
  964         VOP_UNLOCK(vp, 0, td);
  965         vn_finished_write(mp);
  966         vrele(vp);
  967         VFS_UNLOCK_GIANT(vfslocked);
  968         if (!error)
  969                 return;
  970         /*
  971          * If error encountered, give up tracing on this vnode.  We defer
  972          * all the vrele()'s on the vnode until after we are finished walking
  973          * the various lists to avoid needlessly holding locks.
  974          */
  975         log(LOG_NOTICE, "ktrace write failed, errno %d, tracing stopped\n",
  976             error);
  977         vrele_count = 0;
  978         /*
  979          * First, clear this vnode from being used by any processes in the
  980          * system.
  981          * XXX - If one process gets an EPERM writing to the vnode, should
  982          * we really do this?  Other processes might have suitable
  983          * credentials for the operation.
  984          */
  985         cred = NULL;
  986         sx_slock(&allproc_lock);
  987         FOREACH_PROC_IN_SYSTEM(p) {
  988                 PROC_LOCK(p);
  989                 if (p->p_tracevp == vp) {
  990                         mtx_lock(&ktrace_mtx);
  991                         p->p_tracevp = NULL;
  992                         p->p_traceflag = 0;
  993                         cred = p->p_tracecred;
  994                         p->p_tracecred = NULL;
  995                         mtx_unlock(&ktrace_mtx);
  996                         vrele_count++;
  997                 }
  998                 PROC_UNLOCK(p);
  999                 if (cred != NULL) {
 1000                         crfree(cred);
 1001                         cred = NULL;
 1002                 }
 1003         }
 1004         sx_sunlock(&allproc_lock);
 1005 
 1006         /*
 1007          * We can't clear any pending requests in threads that have cached
 1008          * them but not yet committed them, as those are per-thread.  The
 1009          * thread will have to clear it itself on system call return.
 1010          */
 1011         vfslocked = VFS_LOCK_GIANT(vp->v_mount);
 1012         while (vrele_count-- > 0)
 1013                 vrele(vp);
 1014         VFS_UNLOCK_GIANT(vfslocked);
 1015 }
 1016 
 1017 /*
 1018  * Return true if caller has permission to set the ktracing state
 1019  * of target.  Essentially, the target can't possess any
 1020  * more permissions than the caller.  KTRFAC_ROOT signifies that
 1021  * root previously set the tracing status on the target process, and
 1022  * so, only root may further change it.
 1023  */
 1024 static int
 1025 ktrcanset(td, targetp)
 1026         struct thread *td;
 1027         struct proc *targetp;
 1028 {
 1029 
 1030         PROC_LOCK_ASSERT(targetp, MA_OWNED);
 1031         if (targetp->p_traceflag & KTRFAC_ROOT &&
 1032             priv_check(td, PRIV_KTRACE))
 1033                 return (0);
 1034 
 1035         if (p_candebug(td, targetp) != 0)
 1036                 return (0);
 1037 
 1038         return (1);
 1039 }
 1040 
 1041 #endif /* KTRACE */
Cache object: 134ff3bd17ac65988ead19f61c90c582
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FreeBSD/Linux Kernel Cross Reference sys/kern/kern_ktrace.c

FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_ktrace.c
