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: releng/8.2/sys/kern/kern_ktrace.c 202764 2010-01-21 19:11:18Z jhb $");
   36 
   37 #include "opt_ktrace.h"
   38 
   39 #include <sys/param.h>
   40 #include <sys/systm.h>
   41 #include <sys/fcntl.h>
   42 #include <sys/kernel.h>
   43 #include <sys/kthread.h>
   44 #include <sys/lock.h>
   45 #include <sys/mutex.h>
   46 #include <sys/malloc.h>
   47 #include <sys/mount.h>
   48 #include <sys/namei.h>
   49 #include <sys/priv.h>
   50 #include <sys/proc.h>
   51 #include <sys/unistd.h>
   52 #include <sys/vnode.h>
   53 #include <sys/socket.h>
   54 #include <sys/stat.h>
   55 #include <sys/ktrace.h>
   56 #include <sys/sx.h>
   57 #include <sys/sysctl.h>
   58 #include <sys/syslog.h>
   59 #include <sys/sysproto.h>
   60 
   61 #include <security/mac/mac_framework.h>
   62 
   63 /*
   64  * The ktrace facility allows the tracing of certain key events in user space
   65  * processes, such as system calls, signal delivery, context switches, and
   66  * user generated events using utrace(2).  It works by streaming event
   67  * records and data to a vnode associated with the process using the
   68  * ktrace(2) system call.  In general, records can be written directly from
   69  * the context that generates the event.  One important exception to this is
   70  * during a context switch, where sleeping is not permitted.  To handle this
   71  * case, trace events are generated using in-kernel ktr_request records, and
   72  * then delivered to disk at a convenient moment -- either immediately, the
   73  * next traceable event, at system call return, or at process exit.
   74  *
   75  * When dealing with multiple threads or processes writing to the same event
   76  * log, ordering guarantees are weak: specifically, if an event has multiple
   77  * records (i.e., system call enter and return), they may be interlaced with
   78  * records from another event.  Process and thread ID information is provided
   79  * in the record, and user applications can de-interlace events if required.
   80  */
   81 
   82 static MALLOC_DEFINE(M_KTRACE, "KTRACE", "KTRACE");
   83 
   84 #ifdef KTRACE
   85 
   86 #ifndef KTRACE_REQUEST_POOL
   87 #define KTRACE_REQUEST_POOL     100
   88 #endif
   89 
   90 struct ktr_request {
   91         struct  ktr_header ktr_header;
   92         void    *ktr_buffer;
   93         union {
   94                 struct  ktr_syscall ktr_syscall;
   95                 struct  ktr_sysret ktr_sysret;
   96                 struct  ktr_genio ktr_genio;
   97                 struct  ktr_psig ktr_psig;
   98                 struct  ktr_csw ktr_csw;
   99         } ktr_data;
  100         STAILQ_ENTRY(ktr_request) ktr_list;
  101 };
  102 
  103 static int data_lengths[] = {
  104         0,                                      /* none */
  105         offsetof(struct ktr_syscall, ktr_args), /* KTR_SYSCALL */
  106         sizeof(struct ktr_sysret),              /* KTR_SYSRET */
  107         0,                                      /* KTR_NAMEI */
  108         sizeof(struct ktr_genio),               /* KTR_GENIO */
  109         sizeof(struct ktr_psig),                /* KTR_PSIG */
  110         sizeof(struct ktr_csw),                 /* KTR_CSW */
  111         0,                                      /* KTR_USER */
  112         0,                                      /* KTR_STRUCT */
  113         0,                                      /* KTR_SYSCTL */
  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 /* ktr_getrequest() assumes that ktr_comm[] is the same size as td_name[]. */
  260 CTASSERT(sizeof(((struct ktr_header *)NULL)->ktr_comm) ==
  261     (sizeof((struct thread *)NULL)->td_name));
  262 
  263 static struct ktr_request *
  264 ktr_getrequest(int type)
  265 {
  266         struct ktr_request *req;
  267         struct thread *td = curthread;
  268         struct proc *p = td->td_proc;
  269         int pm;
  270 
  271         ktrace_enter(td);       /* XXX: In caller instead? */
  272         mtx_lock(&ktrace_mtx);
  273         if (!KTRCHECK(td, type)) {
  274                 mtx_unlock(&ktrace_mtx);
  275                 ktrace_exit(td);
  276                 return (NULL);
  277         }
  278         req = STAILQ_FIRST(&ktr_free);
  279         if (req != NULL) {
  280                 STAILQ_REMOVE_HEAD(&ktr_free, ktr_list);
  281                 req->ktr_header.ktr_type = type;
  282                 if (p->p_traceflag & KTRFAC_DROP) {
  283                         req->ktr_header.ktr_type |= KTR_DROP;
  284                         p->p_traceflag &= ~KTRFAC_DROP;
  285                 }
  286                 mtx_unlock(&ktrace_mtx);
  287                 microtime(&req->ktr_header.ktr_time);
  288                 req->ktr_header.ktr_pid = p->p_pid;
  289                 req->ktr_header.ktr_tid = td->td_tid;
  290                 bcopy(td->td_name, req->ktr_header.ktr_comm,
  291                     sizeof(req->ktr_header.ktr_comm));
  292                 req->ktr_buffer = NULL;
  293                 req->ktr_header.ktr_len = 0;
  294         } else {
  295                 p->p_traceflag |= KTRFAC_DROP;
  296                 pm = print_message;
  297                 print_message = 0;
  298                 mtx_unlock(&ktrace_mtx);
  299                 if (pm)
  300                         printf("Out of ktrace request objects.\n");
  301                 ktrace_exit(td);
  302         }
  303         return (req);
  304 }
  305 
  306 /*
  307  * Some trace generation environments don't permit direct access to VFS,
  308  * such as during a context switch where sleeping is not allowed.  Under these
  309  * circumstances, queue a request to the thread to be written asynchronously
  310  * later.
  311  */
  312 static void
  313 ktr_enqueuerequest(struct thread *td, struct ktr_request *req)
  314 {
  315 
  316         mtx_lock(&ktrace_mtx);
  317         STAILQ_INSERT_TAIL(&td->td_proc->p_ktr, req, ktr_list);
  318         mtx_unlock(&ktrace_mtx);
  319         ktrace_exit(td);
  320 }
  321 
  322 /*
  323  * Drain any pending ktrace records from the per-thread queue to disk.  This
  324  * is used both internally before committing other records, and also on
  325  * system call return.  We drain all the ones we can find at the time when
  326  * drain is requested, but don't keep draining after that as those events
  327  * may be approximately "after" the current event.
  328  */
  329 static void
  330 ktr_drain(struct thread *td)
  331 {
  332         struct ktr_request *queued_req;
  333         STAILQ_HEAD(, ktr_request) local_queue;
  334 
  335         ktrace_assert(td);
  336         sx_assert(&ktrace_sx, SX_XLOCKED);
  337 
  338         STAILQ_INIT(&local_queue);      /* XXXRW: needed? */
  339 
  340         if (!STAILQ_EMPTY(&td->td_proc->p_ktr)) {
  341                 mtx_lock(&ktrace_mtx);
  342                 STAILQ_CONCAT(&local_queue, &td->td_proc->p_ktr);
  343                 mtx_unlock(&ktrace_mtx);
  344 
  345                 while ((queued_req = STAILQ_FIRST(&local_queue))) {
  346                         STAILQ_REMOVE_HEAD(&local_queue, ktr_list);
  347                         ktr_writerequest(td, queued_req);
  348                         ktr_freerequest(queued_req);
  349                 }
  350         }
  351 }
  352 
  353 /*
  354  * Submit a trace record for immediate commit to disk -- to be used only
  355  * where entering VFS is OK.  First drain any pending records that may have
  356  * been cached in the thread.
  357  */
  358 static void
  359 ktr_submitrequest(struct thread *td, struct ktr_request *req)
  360 {
  361 
  362         ktrace_assert(td);
  363 
  364         sx_xlock(&ktrace_sx);
  365         ktr_drain(td);
  366         ktr_writerequest(td, req);
  367         ktr_freerequest(req);
  368         sx_xunlock(&ktrace_sx);
  369 
  370         ktrace_exit(td);
  371 }
  372 
  373 static void
  374 ktr_freerequest(struct ktr_request *req)
  375 {
  376 
  377         if (req->ktr_buffer != NULL)
  378                 free(req->ktr_buffer, M_KTRACE);
  379         mtx_lock(&ktrace_mtx);
  380         STAILQ_INSERT_HEAD(&ktr_free, req, ktr_list);
  381         mtx_unlock(&ktrace_mtx);
  382 }
  383 
  384 void
  385 ktrsyscall(code, narg, args)
  386         int code, narg;
  387         register_t args[];
  388 {
  389         struct ktr_request *req;
  390         struct ktr_syscall *ktp;
  391         size_t buflen;
  392         char *buf = NULL;
  393 
  394         buflen = sizeof(register_t) * narg;
  395         if (buflen > 0) {
  396                 buf = malloc(buflen, M_KTRACE, M_WAITOK);
  397                 bcopy(args, buf, buflen);
  398         }
  399         req = ktr_getrequest(KTR_SYSCALL);
  400         if (req == NULL) {
  401                 if (buf != NULL)
  402                         free(buf, M_KTRACE);
  403                 return;
  404         }
  405         ktp = &req->ktr_data.ktr_syscall;
  406         ktp->ktr_code = code;
  407         ktp->ktr_narg = narg;
  408         if (buflen > 0) {
  409                 req->ktr_header.ktr_len = buflen;
  410                 req->ktr_buffer = buf;
  411         }
  412         ktr_submitrequest(curthread, req);
  413 }
  414 
  415 void
  416 ktrsysret(code, error, retval)
  417         int code, error;
  418         register_t retval;
  419 {
  420         struct ktr_request *req;
  421         struct ktr_sysret *ktp;
  422 
  423         req = ktr_getrequest(KTR_SYSRET);
  424         if (req == NULL)
  425                 return;
  426         ktp = &req->ktr_data.ktr_sysret;
  427         ktp->ktr_code = code;
  428         ktp->ktr_error = error;
  429         ktp->ktr_retval = retval;               /* what about val2 ? */
  430         ktr_submitrequest(curthread, req);
  431 }
  432 
  433 /*
  434  * When a process exits, drain per-process asynchronous trace records.
  435  */
  436 void
  437 ktrprocexit(struct thread *td)
  438 {
  439 
  440         ktrace_enter(td);
  441         sx_xlock(&ktrace_sx);
  442         ktr_drain(td);
  443         sx_xunlock(&ktrace_sx);
  444         ktrace_exit(td);
  445 }
  446 
  447 /*
  448  * When a thread returns, drain any asynchronous records generated by the
  449  * system call.
  450  */
  451 void
  452 ktruserret(struct thread *td)
  453 {
  454 
  455         ktrace_enter(td);
  456         sx_xlock(&ktrace_sx);
  457         ktr_drain(td);
  458         sx_xunlock(&ktrace_sx);
  459         ktrace_exit(td);
  460 }
  461 
  462 void
  463 ktrnamei(path)
  464         char *path;
  465 {
  466         struct ktr_request *req;
  467         int namelen;
  468         char *buf = NULL;
  469 
  470         namelen = strlen(path);
  471         if (namelen > 0) {
  472                 buf = malloc(namelen, M_KTRACE, M_WAITOK);
  473                 bcopy(path, buf, namelen);
  474         }
  475         req = ktr_getrequest(KTR_NAMEI);
  476         if (req == NULL) {
  477                 if (buf != NULL)
  478                         free(buf, M_KTRACE);
  479                 return;
  480         }
  481         if (namelen > 0) {
  482                 req->ktr_header.ktr_len = namelen;
  483                 req->ktr_buffer = buf;
  484         }
  485         ktr_submitrequest(curthread, req);
  486 }
  487 
  488 void
  489 ktrsysctl(name, namelen)
  490         int *name;
  491         u_int namelen;
  492 {
  493         struct ktr_request *req;
  494         u_int mib[CTL_MAXNAME + 2];
  495         char *mibname;
  496         size_t mibnamelen;
  497         int error;
  498 
  499         /* Lookup name of mib. */    
  500         KASSERT(namelen <= CTL_MAXNAME, ("sysctl MIB too long"));
  501         mib[0] = 0;
  502         mib[1] = 1;
  503         bcopy(name, mib + 2, namelen * sizeof(*name));
  504         mibnamelen = 128;
  505         mibname = malloc(mibnamelen, M_KTRACE, M_WAITOK);
  506         error = kernel_sysctl(curthread, mib, namelen + 2, mibname, &mibnamelen,
  507             NULL, 0, &mibnamelen, 0);
  508         if (error) {
  509                 free(mibname, M_KTRACE);
  510                 return;
  511         }
  512         req = ktr_getrequest(KTR_SYSCTL);
  513         if (req == NULL) {
  514                 free(mibname, M_KTRACE);
  515                 return;
  516         }
  517         req->ktr_header.ktr_len = mibnamelen;
  518         req->ktr_buffer = mibname;
  519         ktr_submitrequest(curthread, req);
  520 }
  521 
  522 void
  523 ktrgenio(fd, rw, uio, error)
  524         int fd;
  525         enum uio_rw rw;
  526         struct uio *uio;
  527         int error;
  528 {
  529         struct ktr_request *req;
  530         struct ktr_genio *ktg;
  531         int datalen;
  532         char *buf;
  533 
  534         if (error) {
  535                 free(uio, M_IOV);
  536                 return;
  537         }
  538         uio->uio_offset = 0;
  539         uio->uio_rw = UIO_WRITE;
  540         datalen = imin(uio->uio_resid, ktr_geniosize);
  541         buf = malloc(datalen, M_KTRACE, M_WAITOK);
  542         error = uiomove(buf, datalen, uio);
  543         free(uio, M_IOV);
  544         if (error) {
  545                 free(buf, M_KTRACE);
  546                 return;
  547         }
  548         req = ktr_getrequest(KTR_GENIO);
  549         if (req == NULL) {
  550                 free(buf, M_KTRACE);
  551                 return;
  552         }
  553         ktg = &req->ktr_data.ktr_genio;
  554         ktg->ktr_fd = fd;
  555         ktg->ktr_rw = rw;
  556         req->ktr_header.ktr_len = datalen;
  557         req->ktr_buffer = buf;
  558         ktr_submitrequest(curthread, req);
  559 }
  560 
  561 void
  562 ktrpsig(sig, action, mask, code)
  563         int sig;
  564         sig_t action;
  565         sigset_t *mask;
  566         int code;
  567 {
  568         struct ktr_request *req;
  569         struct ktr_psig *kp;
  570 
  571         req = ktr_getrequest(KTR_PSIG);
  572         if (req == NULL)
  573                 return;
  574         kp = &req->ktr_data.ktr_psig;
  575         kp->signo = (char)sig;
  576         kp->action = action;
  577         kp->mask = *mask;
  578         kp->code = code;
  579         ktr_enqueuerequest(curthread, req);
  580 }
  581 
  582 void
  583 ktrcsw(out, user)
  584         int out, user;
  585 {
  586         struct ktr_request *req;
  587         struct ktr_csw *kc;
  588 
  589         req = ktr_getrequest(KTR_CSW);
  590         if (req == NULL)
  591                 return;
  592         kc = &req->ktr_data.ktr_csw;
  593         kc->out = out;
  594         kc->user = user;
  595         ktr_enqueuerequest(curthread, req);
  596 }
  597 
  598 void
  599 ktrstruct(name, namelen, data, datalen)
  600         const char *name;
  601         size_t namelen;
  602         void *data;
  603         size_t datalen;
  604 {
  605         struct ktr_request *req;
  606         char *buf = NULL;
  607         size_t buflen;
  608 
  609         if (!data)
  610                 datalen = 0;
  611         buflen = namelen + 1 + datalen;
  612         buf = malloc(buflen, M_KTRACE, M_WAITOK);
  613         bcopy(name, buf, namelen);
  614         buf[namelen] = '\0';
  615         bcopy(data, buf + namelen + 1, datalen);
  616         if ((req = ktr_getrequest(KTR_STRUCT)) == NULL) {
  617                 free(buf, M_KTRACE);
  618                 return;
  619         }
  620         req->ktr_buffer = buf;
  621         req->ktr_header.ktr_len = buflen;
  622         ktr_submitrequest(curthread, req);
  623 }
  624 #endif /* KTRACE */
  625 
  626 /* Interface and common routines */
  627 
  628 #ifndef _SYS_SYSPROTO_H_
  629 struct ktrace_args {
  630         char    *fname;
  631         int     ops;
  632         int     facs;
  633         int     pid;
  634 };
  635 #endif
  636 /* ARGSUSED */
  637 int
  638 ktrace(td, uap)
  639         struct thread *td;
  640         register struct ktrace_args *uap;
  641 {
  642 #ifdef KTRACE
  643         register struct vnode *vp = NULL;
  644         register struct proc *p;
  645         struct pgrp *pg;
  646         int facs = uap->facs & ~KTRFAC_ROOT;
  647         int ops = KTROP(uap->ops);
  648         int descend = uap->ops & KTRFLAG_DESCEND;
  649         int nfound, ret = 0;
  650         int flags, error = 0, vfslocked;
  651         struct nameidata nd;
  652         struct ucred *cred;
  653 
  654         /*
  655          * Need something to (un)trace.
  656          */
  657         if (ops != KTROP_CLEARFILE && facs == 0)
  658                 return (EINVAL);
  659 
  660         ktrace_enter(td);
  661         if (ops != KTROP_CLEAR) {
  662                 /*
  663                  * an operation which requires a file argument.
  664                  */
  665                 NDINIT(&nd, LOOKUP, NOFOLLOW | MPSAFE, UIO_USERSPACE,
  666                     uap->fname, td);
  667                 flags = FREAD | FWRITE | O_NOFOLLOW;
  668                 error = vn_open(&nd, &flags, 0, NULL);
  669                 if (error) {
  670                         ktrace_exit(td);
  671                         return (error);
  672                 }
  673                 vfslocked = NDHASGIANT(&nd);
  674                 NDFREE(&nd, NDF_ONLY_PNBUF);
  675                 vp = nd.ni_vp;
  676                 VOP_UNLOCK(vp, 0);
  677                 if (vp->v_type != VREG) {
  678                         (void) vn_close(vp, FREAD|FWRITE, td->td_ucred, td);
  679                         VFS_UNLOCK_GIANT(vfslocked);
  680                         ktrace_exit(td);
  681                         return (EACCES);
  682                 }
  683                 VFS_UNLOCK_GIANT(vfslocked);
  684         }
  685         /*
  686          * Clear all uses of the tracefile.
  687          */
  688         if (ops == KTROP_CLEARFILE) {
  689                 int vrele_count;
  690 
  691                 vrele_count = 0;
  692                 sx_slock(&allproc_lock);
  693                 FOREACH_PROC_IN_SYSTEM(p) {
  694                         PROC_LOCK(p);
  695                         if (p->p_tracevp == vp) {
  696                                 if (ktrcanset(td, p)) {
  697                                         mtx_lock(&ktrace_mtx);
  698                                         cred = p->p_tracecred;
  699                                         p->p_tracecred = NULL;
  700                                         p->p_tracevp = NULL;
  701                                         p->p_traceflag = 0;
  702                                         mtx_unlock(&ktrace_mtx);
  703                                         vrele_count++;
  704                                         crfree(cred);
  705                                 } else
  706                                         error = EPERM;
  707                         }
  708                         PROC_UNLOCK(p);
  709                 }
  710                 sx_sunlock(&allproc_lock);
  711                 if (vrele_count > 0) {
  712                         vfslocked = VFS_LOCK_GIANT(vp->v_mount);
  713                         while (vrele_count-- > 0)
  714                                 vrele(vp);
  715                         VFS_UNLOCK_GIANT(vfslocked);
  716                 }
  717                 goto done;
  718         }
  719         /*
  720          * do it
  721          */
  722         sx_slock(&proctree_lock);
  723         if (uap->pid < 0) {
  724                 /*
  725                  * by process group
  726                  */
  727                 pg = pgfind(-uap->pid);
  728                 if (pg == NULL) {
  729                         sx_sunlock(&proctree_lock);
  730                         error = ESRCH;
  731                         goto done;
  732                 }
  733                 /*
  734                  * ktrops() may call vrele(). Lock pg_members
  735                  * by the proctree_lock rather than pg_mtx.
  736                  */
  737                 PGRP_UNLOCK(pg);
  738                 nfound = 0;
  739                 LIST_FOREACH(p, &pg->pg_members, p_pglist) {
  740                         PROC_LOCK(p);
  741                         if (p_cansee(td, p) != 0) {
  742                                 PROC_UNLOCK(p); 
  743                                 continue;
  744                         }
  745                         PROC_UNLOCK(p); 
  746                         nfound++;
  747                         if (descend)
  748                                 ret |= ktrsetchildren(td, p, ops, facs, vp);
  749                         else
  750                                 ret |= ktrops(td, p, ops, facs, vp);
  751                 }
  752                 if (nfound == 0) {
  753                         sx_sunlock(&proctree_lock);
  754                         error = ESRCH;
  755                         goto done;
  756                 }
  757         } else {
  758                 /*
  759                  * by pid
  760                  */
  761                 p = pfind(uap->pid);
  762                 if (p == NULL) {
  763                         sx_sunlock(&proctree_lock);
  764                         error = ESRCH;
  765                         goto done;
  766                 }
  767                 error = p_cansee(td, p);
  768                 /*
  769                  * The slock of the proctree lock will keep this process
  770                  * from going away, so unlocking the proc here is ok.
  771                  */
  772                 PROC_UNLOCK(p);
  773                 if (error) {
  774                         sx_sunlock(&proctree_lock);
  775                         goto done;
  776                 }
  777                 if (descend)
  778                         ret |= ktrsetchildren(td, p, ops, facs, vp);
  779                 else
  780                         ret |= ktrops(td, p, ops, facs, vp);
  781         }
  782         sx_sunlock(&proctree_lock);
  783         if (!ret)
  784                 error = EPERM;
  785 done:
  786         if (vp != NULL) {
  787                 vfslocked = VFS_LOCK_GIANT(vp->v_mount);
  788                 (void) vn_close(vp, FWRITE, td->td_ucred, td);
  789                 VFS_UNLOCK_GIANT(vfslocked);
  790         }
  791         ktrace_exit(td);
  792         return (error);
  793 #else /* !KTRACE */
  794         return (ENOSYS);
  795 #endif /* KTRACE */
  796 }
  797 
  798 /* ARGSUSED */
  799 int
  800 utrace(td, uap)
  801         struct thread *td;
  802         register struct utrace_args *uap;
  803 {
  804 
  805 #ifdef KTRACE
  806         struct ktr_request *req;
  807         void *cp;
  808         int error;
  809 
  810         if (!KTRPOINT(td, KTR_USER))
  811                 return (0);
  812         if (uap->len > KTR_USER_MAXLEN)
  813                 return (EINVAL);
  814         cp = malloc(uap->len, M_KTRACE, M_WAITOK);
  815         error = copyin(uap->addr, cp, uap->len);
  816         if (error) {
  817                 free(cp, M_KTRACE);
  818                 return (error);
  819         }
  820         req = ktr_getrequest(KTR_USER);
  821         if (req == NULL) {
  822                 free(cp, M_KTRACE);
  823                 return (ENOMEM);
  824         }
  825         req->ktr_buffer = cp;
  826         req->ktr_header.ktr_len = uap->len;
  827         ktr_submitrequest(td, req);
  828         return (0);
  829 #else /* !KTRACE */
  830         return (ENOSYS);
  831 #endif /* KTRACE */
  832 }
  833 
  834 #ifdef KTRACE
  835 static int
  836 ktrops(td, p, ops, facs, vp)
  837         struct thread *td;
  838         struct proc *p;
  839         int ops, facs;
  840         struct vnode *vp;
  841 {
  842         struct vnode *tracevp = NULL;
  843         struct ucred *tracecred = NULL;
  844 
  845         PROC_LOCK(p);
  846         if (!ktrcanset(td, p)) {
  847                 PROC_UNLOCK(p);
  848                 return (0);
  849         }
  850         mtx_lock(&ktrace_mtx);
  851         if (ops == KTROP_SET) {
  852                 if (p->p_tracevp != vp) {
  853                         /*
  854                          * if trace file already in use, relinquish below
  855                          */
  856                         tracevp = p->p_tracevp;
  857                         VREF(vp);
  858                         p->p_tracevp = vp;
  859                 }
  860                 if (p->p_tracecred != td->td_ucred) {
  861                         tracecred = p->p_tracecred;
  862                         p->p_tracecred = crhold(td->td_ucred);
  863                 }
  864                 p->p_traceflag |= facs;
  865                 if (priv_check(td, PRIV_KTRACE) == 0)
  866                         p->p_traceflag |= KTRFAC_ROOT;
  867         } else {
  868                 /* KTROP_CLEAR */
  869                 if (((p->p_traceflag &= ~facs) & KTRFAC_MASK) == 0) {
  870                         /* no more tracing */
  871                         p->p_traceflag = 0;
  872                         tracevp = p->p_tracevp;
  873                         p->p_tracevp = NULL;
  874                         tracecred = p->p_tracecred;
  875                         p->p_tracecred = NULL;
  876                 }
  877         }
  878         mtx_unlock(&ktrace_mtx);
  879         PROC_UNLOCK(p);
  880         if (tracevp != NULL) {
  881                 int vfslocked;
  882 
  883                 vfslocked = VFS_LOCK_GIANT(tracevp->v_mount);
  884                 vrele(tracevp);
  885                 VFS_UNLOCK_GIANT(vfslocked);
  886         }
  887         if (tracecred != NULL)
  888                 crfree(tracecred);
  889 
  890         return (1);
  891 }
  892 
  893 static int
  894 ktrsetchildren(td, top, ops, facs, vp)
  895         struct thread *td;
  896         struct proc *top;
  897         int ops, facs;
  898         struct vnode *vp;
  899 {
  900         register struct proc *p;
  901         register int ret = 0;
  902 
  903         p = top;
  904         sx_assert(&proctree_lock, SX_LOCKED);
  905         for (;;) {
  906                 ret |= ktrops(td, p, ops, facs, vp);
  907                 /*
  908                  * If this process has children, descend to them next,
  909                  * otherwise do any siblings, and if done with this level,
  910                  * follow back up the tree (but not past top).
  911                  */
  912                 if (!LIST_EMPTY(&p->p_children))
  913                         p = LIST_FIRST(&p->p_children);
  914                 else for (;;) {
  915                         if (p == top)
  916                                 return (ret);
  917                         if (LIST_NEXT(p, p_sibling)) {
  918                                 p = LIST_NEXT(p, p_sibling);
  919                                 break;
  920                         }
  921                         p = p->p_pptr;
  922                 }
  923         }
  924         /*NOTREACHED*/
  925 }
  926 
  927 static void
  928 ktr_writerequest(struct thread *td, struct ktr_request *req)
  929 {
  930         struct ktr_header *kth;
  931         struct vnode *vp;
  932         struct proc *p;
  933         struct ucred *cred;
  934         struct uio auio;
  935         struct iovec aiov[3];
  936         struct mount *mp;
  937         int datalen, buflen, vrele_count;
  938         int error, vfslocked;
  939 
  940         /*
  941          * We hold the vnode and credential for use in I/O in case ktrace is
  942          * disabled on the process as we write out the request.
  943          *
  944          * XXXRW: This is not ideal: we could end up performing a write after
  945          * the vnode has been closed.
  946          */
  947         mtx_lock(&ktrace_mtx);
  948         vp = td->td_proc->p_tracevp;
  949         cred = td->td_proc->p_tracecred;
  950 
  951         /*
  952          * If vp is NULL, the vp has been cleared out from under this
  953          * request, so just drop it.  Make sure the credential and vnode are
  954          * in sync: we should have both or neither.
  955          */
  956         if (vp == NULL) {
  957                 KASSERT(cred == NULL, ("ktr_writerequest: cred != NULL"));
  958                 mtx_unlock(&ktrace_mtx);
  959                 return;
  960         }
  961         VREF(vp);
  962         KASSERT(cred != NULL, ("ktr_writerequest: cred == NULL"));
  963         crhold(cred);
  964         mtx_unlock(&ktrace_mtx);
  965 
  966         kth = &req->ktr_header;
  967         KASSERT(((u_short)kth->ktr_type & ~KTR_DROP) <
  968             sizeof(data_lengths) / sizeof(data_lengths[0]),
  969             ("data_lengths array overflow"));
  970         datalen = data_lengths[(u_short)kth->ktr_type & ~KTR_DROP];
  971         buflen = kth->ktr_len;
  972         auio.uio_iov = &aiov[0];
  973         auio.uio_offset = 0;
  974         auio.uio_segflg = UIO_SYSSPACE;
  975         auio.uio_rw = UIO_WRITE;
  976         aiov[0].iov_base = (caddr_t)kth;
  977         aiov[0].iov_len = sizeof(struct ktr_header);
  978         auio.uio_resid = sizeof(struct ktr_header);
  979         auio.uio_iovcnt = 1;
  980         auio.uio_td = td;
  981         if (datalen != 0) {
  982                 aiov[1].iov_base = (caddr_t)&req->ktr_data;
  983                 aiov[1].iov_len = datalen;
  984                 auio.uio_resid += datalen;
  985                 auio.uio_iovcnt++;
  986                 kth->ktr_len += datalen;
  987         }
  988         if (buflen != 0) {
  989                 KASSERT(req->ktr_buffer != NULL, ("ktrace: nothing to write"));
  990                 aiov[auio.uio_iovcnt].iov_base = req->ktr_buffer;
  991                 aiov[auio.uio_iovcnt].iov_len = buflen;
  992                 auio.uio_resid += buflen;
  993                 auio.uio_iovcnt++;
  994         }
  995 
  996         vfslocked = VFS_LOCK_GIANT(vp->v_mount);
  997         vn_start_write(vp, &mp, V_WAIT);
  998         vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
  999 #ifdef MAC
 1000         error = mac_vnode_check_write(cred, NOCRED, vp);
 1001         if (error == 0)
 1002 #endif
 1003                 error = VOP_WRITE(vp, &auio, IO_UNIT | IO_APPEND, cred);
 1004         VOP_UNLOCK(vp, 0);
 1005         vn_finished_write(mp);
 1006         crfree(cred);
 1007         if (!error) {
 1008                 vrele(vp);
 1009                 VFS_UNLOCK_GIANT(vfslocked);
 1010                 return;
 1011         }
 1012         VFS_UNLOCK_GIANT(vfslocked);
 1013 
 1014         /*
 1015          * If error encountered, give up tracing on this vnode.  We defer
 1016          * all the vrele()'s on the vnode until after we are finished walking
 1017          * the various lists to avoid needlessly holding locks.
 1018          * NB: at this point we still hold the vnode reference that must
 1019          * not go away as we need the valid vnode to compare with. Thus let
 1020          * vrele_count start at 1 and the reference will be freed
 1021          * by the loop at the end after our last use of vp.
 1022          */
 1023         log(LOG_NOTICE, "ktrace write failed, errno %d, tracing stopped\n",
 1024             error);
 1025         vrele_count = 1;
 1026         /*
 1027          * First, clear this vnode from being used by any processes in the
 1028          * system.
 1029          * XXX - If one process gets an EPERM writing to the vnode, should
 1030          * we really do this?  Other processes might have suitable
 1031          * credentials for the operation.
 1032          */
 1033         cred = NULL;
 1034         sx_slock(&allproc_lock);
 1035         FOREACH_PROC_IN_SYSTEM(p) {
 1036                 PROC_LOCK(p);
 1037                 if (p->p_tracevp == vp) {
 1038                         mtx_lock(&ktrace_mtx);
 1039                         p->p_tracevp = NULL;
 1040                         p->p_traceflag = 0;
 1041                         cred = p->p_tracecred;
 1042                         p->p_tracecred = NULL;
 1043                         mtx_unlock(&ktrace_mtx);
 1044                         vrele_count++;
 1045                 }
 1046                 PROC_UNLOCK(p);
 1047                 if (cred != NULL) {
 1048                         crfree(cred);
 1049                         cred = NULL;
 1050                 }
 1051         }
 1052         sx_sunlock(&allproc_lock);
 1053 
 1054         /*
 1055          * We can't clear any pending requests in threads that have cached
 1056          * them but not yet committed them, as those are per-thread.  The
 1057          * thread will have to clear it itself on system call return.
 1058          */
 1059         vfslocked = VFS_LOCK_GIANT(vp->v_mount);
 1060         while (vrele_count-- > 0)
 1061                 vrele(vp);
 1062         VFS_UNLOCK_GIANT(vfslocked);
 1063 }
 1064 
 1065 /*
 1066  * Return true if caller has permission to set the ktracing state
 1067  * of target.  Essentially, the target can't possess any
 1068  * more permissions than the caller.  KTRFAC_ROOT signifies that
 1069  * root previously set the tracing status on the target process, and
 1070  * so, only root may further change it.
 1071  */
 1072 static int
 1073 ktrcanset(td, targetp)
 1074         struct thread *td;
 1075         struct proc *targetp;
 1076 {
 1077 
 1078         PROC_LOCK_ASSERT(targetp, MA_OWNED);
 1079         if (targetp->p_traceflag & KTRFAC_ROOT &&
 1080             priv_check(td, PRIV_KTRACE))
 1081                 return (0);
 1082 
 1083         if (p_candebug(td, targetp) != 0)
 1084                 return (0);
 1085 
 1086         return (1);
 1087 }
 1088 
 1089 #endif /* KTRACE */
Cache object: 38780d5cb374e100d9f63cdaa4f2ef18
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FreeBSD/Linux Kernel Cross Reference sys/kern/kern_ktrace.c

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