kern_ktrace.c

Version: - FREEBSD - FREEBSD-13-STABLE - FREEBSD-13-0 - FREEBSD-12-STABLE - FREEBSD-12-0 - FREEBSD-11-STABLE - FREEBSD-11-0 - FREEBSD-10-STABLE - FREEBSD-10-0 - FREEBSD-9-STABLE - FREEBSD-9-0 - FREEBSD-8-STABLE - FREEBSD-8-0 - FREEBSD-7-STABLE - FREEBSD-7-0 - FREEBSD-6-STABLE - FREEBSD-6-0 - FREEBSD-5-STABLE - FREEBSD-5-0 - FREEBSD-4-STABLE - FREEBSD-3-STABLE - FREEBSD22 - l41 - OPENBSD - linux-2.6 - MK84 - PLAN9 - xnu-8792
SearchContext: - none - 3 - 10
    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/7.3/sys/kern/kern_ktrace.c 202765 2010-01-21 19:17:42Z jhb $");
   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         0,                                      /* KTR_SYSCTL */
  115 };
  116 
  117 static STAILQ_HEAD(, ktr_request) ktr_free;
  118 
  119 static SYSCTL_NODE(_kern, OID_AUTO, ktrace, CTLFLAG_RD, 0, "KTRACE options");
  120 
  121 static u_int ktr_requestpool = KTRACE_REQUEST_POOL;
  122 TUNABLE_INT("kern.ktrace.request_pool", &ktr_requestpool);
  123 
  124 static u_int ktr_geniosize = PAGE_SIZE;
  125 TUNABLE_INT("kern.ktrace.genio_size", &ktr_geniosize);
  126 SYSCTL_UINT(_kern_ktrace, OID_AUTO, genio_size, CTLFLAG_RW, &ktr_geniosize,
  127     0, "Maximum size of genio event payload");
  128 
  129 static int print_message = 1;
  130 struct mtx ktrace_mtx;
  131 static struct sx ktrace_sx;
  132 
  133 static void ktrace_init(void *dummy);
  134 static int sysctl_kern_ktrace_request_pool(SYSCTL_HANDLER_ARGS);
  135 static u_int ktrace_resize_pool(u_int newsize);
  136 static struct ktr_request *ktr_getrequest(int type);
  137 static void ktr_submitrequest(struct thread *td, struct ktr_request *req);
  138 static void ktr_freerequest(struct ktr_request *req);
  139 static void ktr_writerequest(struct thread *td, struct ktr_request *req);
  140 static int ktrcanset(struct thread *,struct proc *);
  141 static int ktrsetchildren(struct thread *,struct proc *,int,int,struct vnode *);
  142 static int ktrops(struct thread *,struct proc *,int,int,struct vnode *);
  143 
  144 /*
  145  * ktrace itself generates events, such as context switches, which we do not
  146  * wish to trace.  Maintain a flag, TDP_INKTRACE, on each thread to determine
  147  * whether or not it is in a region where tracing of events should be
  148  * suppressed.
  149  */
  150 static void
  151 ktrace_enter(struct thread *td)
  152 {
  153 
  154         KASSERT(!(td->td_pflags & TDP_INKTRACE), ("ktrace_enter: flag set"));
  155         td->td_pflags |= TDP_INKTRACE;
  156 }
  157 
  158 static void
  159 ktrace_exit(struct thread *td)
  160 {
  161 
  162         KASSERT(td->td_pflags & TDP_INKTRACE, ("ktrace_exit: flag not set"));
  163         td->td_pflags &= ~TDP_INKTRACE;
  164 }
  165 
  166 static void
  167 ktrace_assert(struct thread *td)
  168 {
  169 
  170         KASSERT(td->td_pflags & TDP_INKTRACE, ("ktrace_assert: flag not set"));
  171 }
  172 
  173 static void
  174 ktrace_init(void *dummy)
  175 {
  176         struct ktr_request *req;
  177         int i;
  178 
  179         mtx_init(&ktrace_mtx, "ktrace", NULL, MTX_DEF | MTX_QUIET);
  180         sx_init(&ktrace_sx, "ktrace_sx");
  181         STAILQ_INIT(&ktr_free);
  182         for (i = 0; i < ktr_requestpool; i++) {
  183                 req = malloc(sizeof(struct ktr_request), M_KTRACE, M_WAITOK);
  184                 STAILQ_INSERT_HEAD(&ktr_free, req, ktr_list);
  185         }
  186 }
  187 SYSINIT(ktrace_init, SI_SUB_KTRACE, SI_ORDER_ANY, ktrace_init, NULL);
  188 
  189 static int
  190 sysctl_kern_ktrace_request_pool(SYSCTL_HANDLER_ARGS)
  191 {
  192         struct thread *td;
  193         u_int newsize, oldsize, wantsize;
  194         int error;
  195 
  196         /* Handle easy read-only case first to avoid warnings from GCC. */
  197         if (!req->newptr) {
  198                 mtx_lock(&ktrace_mtx);
  199                 oldsize = ktr_requestpool;
  200                 mtx_unlock(&ktrace_mtx);
  201                 return (SYSCTL_OUT(req, &oldsize, sizeof(u_int)));
  202         }
  203 
  204         error = SYSCTL_IN(req, &wantsize, sizeof(u_int));
  205         if (error)
  206                 return (error);
  207         td = curthread;
  208         ktrace_enter(td);
  209         mtx_lock(&ktrace_mtx);
  210         oldsize = ktr_requestpool;
  211         newsize = ktrace_resize_pool(wantsize);
  212         mtx_unlock(&ktrace_mtx);
  213         ktrace_exit(td);
  214         error = SYSCTL_OUT(req, &oldsize, sizeof(u_int));
  215         if (error)
  216                 return (error);
  217         if (wantsize > oldsize && newsize < wantsize)
  218                 return (ENOSPC);
  219         return (0);
  220 }
  221 SYSCTL_PROC(_kern_ktrace, OID_AUTO, request_pool, CTLTYPE_UINT|CTLFLAG_RW,
  222     &ktr_requestpool, 0, sysctl_kern_ktrace_request_pool, "IU", "");
  223 
  224 static u_int
  225 ktrace_resize_pool(u_int newsize)
  226 {
  227         struct ktr_request *req;
  228         int bound;
  229 
  230         mtx_assert(&ktrace_mtx, MA_OWNED);
  231         print_message = 1;
  232         bound = newsize - ktr_requestpool;
  233         if (bound == 0)
  234                 return (ktr_requestpool);
  235         if (bound < 0)
  236                 /* Shrink pool down to newsize if possible. */
  237                 while (bound++ < 0) {
  238                         req = STAILQ_FIRST(&ktr_free);
  239                         if (req == NULL)
  240                                 return (ktr_requestpool);
  241                         STAILQ_REMOVE_HEAD(&ktr_free, ktr_list);
  242                         ktr_requestpool--;
  243                         mtx_unlock(&ktrace_mtx);
  244                         free(req, M_KTRACE);
  245                         mtx_lock(&ktrace_mtx);
  246                 }
  247         else
  248                 /* Grow pool up to newsize. */
  249                 while (bound-- > 0) {
  250                         mtx_unlock(&ktrace_mtx);
  251                         req = malloc(sizeof(struct ktr_request), M_KTRACE,
  252                             M_WAITOK);
  253                         mtx_lock(&ktrace_mtx);
  254                         STAILQ_INSERT_HEAD(&ktr_free, req, ktr_list);
  255                         ktr_requestpool++;
  256                 }
  257         return (ktr_requestpool);
  258 }
  259 
  260 /* ktr_getrequest() assumes that ktr_comm[] is the same size as p_comm[]. */
  261 CTASSERT(sizeof(((struct ktr_header *)NULL)->ktr_comm) ==
  262     (sizeof((struct proc *)NULL)->p_comm));
  263 
  264 static struct ktr_request *
  265 ktr_getrequest(int type)
  266 {
  267         struct ktr_request *req;
  268         struct thread *td = curthread;
  269         struct proc *p = td->td_proc;
  270         int pm;
  271 
  272         ktrace_enter(td);       /* XXX: In caller instead? */
  273         mtx_lock(&ktrace_mtx);
  274         if (!KTRCHECK(td, type)) {
  275                 mtx_unlock(&ktrace_mtx);
  276                 ktrace_exit(td);
  277                 return (NULL);
  278         }
  279         req = STAILQ_FIRST(&ktr_free);
  280         if (req != NULL) {
  281                 STAILQ_REMOVE_HEAD(&ktr_free, ktr_list);
  282                 req->ktr_header.ktr_type = type;
  283                 if (p->p_traceflag & KTRFAC_DROP) {
  284                         req->ktr_header.ktr_type |= KTR_DROP;
  285                         p->p_traceflag &= ~KTRFAC_DROP;
  286                 }
  287                 mtx_unlock(&ktrace_mtx);
  288                 microtime(&req->ktr_header.ktr_time);
  289                 req->ktr_header.ktr_pid = p->p_pid;
  290                 req->ktr_header.ktr_tid = td->td_tid;
  291                 bcopy(p->p_comm, req->ktr_header.ktr_comm,
  292                     sizeof(req->ktr_header.ktr_comm));
  293                 req->ktr_buffer = NULL;
  294                 req->ktr_header.ktr_len = 0;
  295         } else {
  296                 p->p_traceflag |= KTRFAC_DROP;
  297                 pm = print_message;
  298                 print_message = 0;
  299                 mtx_unlock(&ktrace_mtx);
  300                 if (pm)
  301                         printf("Out of ktrace request objects.\n");
  302                 ktrace_exit(td);
  303         }
  304         return (req);
  305 }
  306 
  307 /*
  308  * Some trace generation environments don't permit direct access to VFS,
  309  * such as during a context switch where sleeping is not allowed.  Under these
  310  * circumstances, queue a request to the thread to be written asynchronously
  311  * later.
  312  */
  313 static void
  314 ktr_enqueuerequest(struct thread *td, struct ktr_request *req)
  315 {
  316 
  317         mtx_lock(&ktrace_mtx);
  318         STAILQ_INSERT_TAIL(&td->td_proc->p_ktr, req, ktr_list);
  319         mtx_unlock(&ktrace_mtx);
  320         ktrace_exit(td);
  321 }
  322 
  323 /*
  324  * Drain any pending ktrace records from the per-thread queue to disk.  This
  325  * is used both internally before committing other records, and also on
  326  * system call return.  We drain all the ones we can find at the time when
  327  * drain is requested, but don't keep draining after that as those events
  328  * may be approximately "after" the current event.
  329  */
  330 static void
  331 ktr_drain(struct thread *td)
  332 {
  333         struct ktr_request *queued_req;
  334         STAILQ_HEAD(, ktr_request) local_queue;
  335 
  336         ktrace_assert(td);
  337         sx_assert(&ktrace_sx, SX_XLOCKED);
  338 
  339         STAILQ_INIT(&local_queue);      /* XXXRW: needed? */
  340 
  341         if (!STAILQ_EMPTY(&td->td_proc->p_ktr)) {
  342                 mtx_lock(&ktrace_mtx);
  343                 STAILQ_CONCAT(&local_queue, &td->td_proc->p_ktr);
  344                 mtx_unlock(&ktrace_mtx);
  345 
  346                 while ((queued_req = STAILQ_FIRST(&local_queue))) {
  347                         STAILQ_REMOVE_HEAD(&local_queue, ktr_list);
  348                         ktr_writerequest(td, queued_req);
  349                         ktr_freerequest(queued_req);
  350                 }
  351         }
  352 }
  353 
  354 /*
  355  * Submit a trace record for immediate commit to disk -- to be used only
  356  * where entering VFS is OK.  First drain any pending records that may have
  357  * been cached in the thread.
  358  */
  359 static void
  360 ktr_submitrequest(struct thread *td, struct ktr_request *req)
  361 {
  362 
  363         ktrace_assert(td);
  364 
  365         sx_xlock(&ktrace_sx);
  366         ktr_drain(td);
  367         ktr_writerequest(td, req);
  368         ktr_freerequest(req);
  369         sx_xunlock(&ktrace_sx);
  370 
  371         ktrace_exit(td);
  372 }
  373 
  374 static void
  375 ktr_freerequest(struct ktr_request *req)
  376 {
  377 
  378         if (req->ktr_buffer != NULL)
  379                 free(req->ktr_buffer, M_KTRACE);
  380         mtx_lock(&ktrace_mtx);
  381         STAILQ_INSERT_HEAD(&ktr_free, req, ktr_list);
  382         mtx_unlock(&ktrace_mtx);
  383 }
  384 
  385 void
  386 ktrsyscall(code, narg, args)
  387         int code, narg;
  388         register_t args[];
  389 {
  390         struct ktr_request *req;
  391         struct ktr_syscall *ktp;
  392         size_t buflen;
  393         char *buf = NULL;
  394 
  395         buflen = sizeof(register_t) * narg;
  396         if (buflen > 0) {
  397                 buf = malloc(buflen, M_KTRACE, M_WAITOK);
  398                 bcopy(args, buf, buflen);
  399         }
  400         req = ktr_getrequest(KTR_SYSCALL);
  401         if (req == NULL) {
  402                 if (buf != NULL)
  403                         free(buf, M_KTRACE);
  404                 return;
  405         }
  406         ktp = &req->ktr_data.ktr_syscall;
  407         ktp->ktr_code = code;
  408         ktp->ktr_narg = narg;
  409         if (buflen > 0) {
  410                 req->ktr_header.ktr_len = buflen;
  411                 req->ktr_buffer = buf;
  412         }
  413         ktr_submitrequest(curthread, req);
  414 }
  415 
  416 void
  417 ktrsysret(code, error, retval)
  418         int code, error;
  419         register_t retval;
  420 {
  421         struct ktr_request *req;
  422         struct ktr_sysret *ktp;
  423 
  424         req = ktr_getrequest(KTR_SYSRET);
  425         if (req == NULL)
  426                 return;
  427         ktp = &req->ktr_data.ktr_sysret;
  428         ktp->ktr_code = code;
  429         ktp->ktr_error = error;
  430         ktp->ktr_retval = retval;               /* what about val2 ? */
  431         ktr_submitrequest(curthread, req);
  432 }
  433 
  434 /*
  435  * When a process exits, drain per-process asynchronous trace records.
  436  */
  437 void
  438 ktrprocexit(struct thread *td)
  439 {
  440 
  441         ktrace_enter(td);
  442         sx_xlock(&ktrace_sx);
  443         ktr_drain(td);
  444         sx_xunlock(&ktrace_sx);
  445         ktrace_exit(td);
  446 }
  447 
  448 /*
  449  * When a thread returns, drain any asynchronous records generated by the
  450  * system call.
  451  */
  452 void
  453 ktruserret(struct thread *td)
  454 {
  455 
  456         ktrace_enter(td);
  457         sx_xlock(&ktrace_sx);
  458         ktr_drain(td);
  459         sx_xunlock(&ktrace_sx);
  460         ktrace_exit(td);
  461 }
  462 
  463 void
  464 ktrnamei(path)
  465         char *path;
  466 {
  467         struct ktr_request *req;
  468         int namelen;
  469         char *buf = NULL;
  470 
  471         namelen = strlen(path);
  472         if (namelen > 0) {
  473                 buf = malloc(namelen, M_KTRACE, M_WAITOK);
  474                 bcopy(path, buf, namelen);
  475         }
  476         req = ktr_getrequest(KTR_NAMEI);
  477         if (req == NULL) {
  478                 if (buf != NULL)
  479                         free(buf, M_KTRACE);
  480                 return;
  481         }
  482         if (namelen > 0) {
  483                 req->ktr_header.ktr_len = namelen;
  484                 req->ktr_buffer = buf;
  485         }
  486         ktr_submitrequest(curthread, req);
  487 }
  488 
  489 void
  490 ktrsysctl(name, namelen)
  491         int *name;
  492         u_int namelen;
  493 {
  494         struct ktr_request *req;
  495         u_int mib[CTL_MAXNAME + 2];
  496         char *mibname;
  497         size_t mibnamelen;
  498         int error;
  499 
  500         /* Lookup name of mib. */    
  501         KASSERT(namelen <= CTL_MAXNAME, ("sysctl MIB too long"));
  502         mib[0] = 0;
  503         mib[1] = 1;
  504         bcopy(name, mib + 2, namelen * sizeof(*name));
  505         mibnamelen = 128;
  506         mibname = malloc(mibnamelen, M_KTRACE, M_WAITOK);
  507         error = kernel_sysctl(curthread, mib, namelen + 2, mibname, &mibnamelen,
  508             NULL, 0, &mibnamelen, 0);
  509         if (error) {
  510                 free(mibname, M_KTRACE);
  511                 return;
  512         }
  513         req = ktr_getrequest(KTR_SYSCTL);
  514         if (req == NULL) {
  515                 free(mibname, M_KTRACE);
  516                 return;
  517         }
  518         req->ktr_header.ktr_len = mibnamelen;
  519         req->ktr_buffer = mibname;
  520         ktr_submitrequest(curthread, req);
  521 }
  522 
  523 void
  524 ktrgenio(fd, rw, uio, error)
  525         int fd;
  526         enum uio_rw rw;
  527         struct uio *uio;
  528         int error;
  529 {
  530         struct ktr_request *req;
  531         struct ktr_genio *ktg;
  532         int datalen;
  533         char *buf;
  534 
  535         if (error) {
  536                 free(uio, M_IOV);
  537                 return;
  538         }
  539         uio->uio_offset = 0;
  540         uio->uio_rw = UIO_WRITE;
  541         datalen = imin(uio->uio_resid, ktr_geniosize);
  542         buf = malloc(datalen, M_KTRACE, M_WAITOK);
  543         error = uiomove(buf, datalen, uio);
  544         free(uio, M_IOV);
  545         if (error) {
  546                 free(buf, M_KTRACE);
  547                 return;
  548         }
  549         req = ktr_getrequest(KTR_GENIO);
  550         if (req == NULL) {
  551                 free(buf, M_KTRACE);
  552                 return;
  553         }
  554         ktg = &req->ktr_data.ktr_genio;
  555         ktg->ktr_fd = fd;
  556         ktg->ktr_rw = rw;
  557         req->ktr_header.ktr_len = datalen;
  558         req->ktr_buffer = buf;
  559         ktr_submitrequest(curthread, req);
  560 }
  561 
  562 void
  563 ktrpsig(sig, action, mask, code)
  564         int sig;
  565         sig_t action;
  566         sigset_t *mask;
  567         int code;
  568 {
  569         struct ktr_request *req;
  570         struct ktr_psig *kp;
  571 
  572         req = ktr_getrequest(KTR_PSIG);
  573         if (req == NULL)
  574                 return;
  575         kp = &req->ktr_data.ktr_psig;
  576         kp->signo = (char)sig;
  577         kp->action = action;
  578         kp->mask = *mask;
  579         kp->code = code;
  580         ktr_enqueuerequest(curthread, req);
  581 }
  582 
  583 void
  584 ktrcsw(out, user)
  585         int out, user;
  586 {
  587         struct ktr_request *req;
  588         struct ktr_csw *kc;
  589 
  590         req = ktr_getrequest(KTR_CSW);
  591         if (req == NULL)
  592                 return;
  593         kc = &req->ktr_data.ktr_csw;
  594         kc->out = out;
  595         kc->user = user;
  596         ktr_enqueuerequest(curthread, req);
  597 }
  598 
  599 void
  600 ktrstruct(name, namelen, data, datalen)
  601         const char *name;
  602         size_t namelen;
  603         void *data;
  604         size_t datalen;
  605 {
  606         struct ktr_request *req;
  607         char *buf = NULL;
  608         size_t buflen;
  609 
  610         if (!data)
  611                 datalen = 0;
  612         buflen = namelen + 1 + datalen;
  613         buf = malloc(buflen, M_KTRACE, M_WAITOK);
  614         bcopy(name, buf, namelen);
  615         buf[namelen] = '\0';
  616         bcopy(data, buf + namelen + 1, datalen);
  617         if ((req = ktr_getrequest(KTR_STRUCT)) == NULL) {
  618                 free(buf, M_KTRACE);
  619                 return;
  620         }
  621         req->ktr_buffer = buf;
  622         req->ktr_header.ktr_len = buflen;
  623         ktr_submitrequest(curthread, req);
  624 }
  625 #endif /* KTRACE */
  626 
  627 /* Interface and common routines */
  628 
  629 #ifndef _SYS_SYSPROTO_H_
  630 struct ktrace_args {
  631         char    *fname;
  632         int     ops;
  633         int     facs;
  634         int     pid;
  635 };
  636 #endif
  637 /* ARGSUSED */
  638 int
  639 ktrace(td, uap)
  640         struct thread *td;
  641         register struct ktrace_args *uap;
  642 {
  643 #ifdef KTRACE
  644         register struct vnode *vp = NULL;
  645         register struct proc *p;
  646         struct pgrp *pg;
  647         int facs = uap->facs & ~KTRFAC_ROOT;
  648         int ops = KTROP(uap->ops);
  649         int descend = uap->ops & KTRFLAG_DESCEND;
  650         int nfound, ret = 0;
  651         int flags, error = 0, vfslocked;
  652         struct nameidata nd;
  653         struct ucred *cred;
  654 
  655         /*
  656          * Need something to (un)trace.
  657          */
  658         if (ops != KTROP_CLEARFILE && facs == 0)
  659                 return (EINVAL);
  660 
  661         ktrace_enter(td);
  662         if (ops != KTROP_CLEAR) {
  663                 /*
  664                  * an operation which requires a file argument.
  665                  */
  666                 NDINIT(&nd, LOOKUP, NOFOLLOW | MPSAFE, UIO_USERSPACE,
  667                     uap->fname, td);
  668                 flags = FREAD | FWRITE | O_NOFOLLOW;
  669                 error = vn_open(&nd, &flags, 0, NULL);
  670                 if (error) {
  671                         ktrace_exit(td);
  672                         return (error);
  673                 }
  674                 vfslocked = NDHASGIANT(&nd);
  675                 NDFREE(&nd, NDF_ONLY_PNBUF);
  676                 vp = nd.ni_vp;
  677                 VOP_UNLOCK(vp, 0, td);
  678                 if (vp->v_type != VREG) {
  679                         (void) vn_close(vp, FREAD|FWRITE, td->td_ucred, td);
  680                         VFS_UNLOCK_GIANT(vfslocked);
  681                         ktrace_exit(td);
  682                         return (EACCES);
  683                 }
  684                 VFS_UNLOCK_GIANT(vfslocked);
  685         }
  686         /*
  687          * Clear all uses of the tracefile.
  688          */
  689         if (ops == KTROP_CLEARFILE) {
  690                 int vrele_count;
  691 
  692                 vrele_count = 0;
  693                 sx_slock(&allproc_lock);
  694                 FOREACH_PROC_IN_SYSTEM(p) {
  695                         PROC_LOCK(p);
  696                         if (p->p_tracevp == vp) {
  697                                 if (ktrcanset(td, p)) {
  698                                         mtx_lock(&ktrace_mtx);
  699                                         cred = p->p_tracecred;
  700                                         p->p_tracecred = NULL;
  701                                         p->p_tracevp = NULL;
  702                                         p->p_traceflag = 0;
  703                                         mtx_unlock(&ktrace_mtx);
  704                                         vrele_count++;
  705                                         crfree(cred);
  706                                 } else
  707                                         error = EPERM;
  708                         }
  709                         PROC_UNLOCK(p);
  710                 }
  711                 sx_sunlock(&allproc_lock);
  712                 if (vrele_count > 0) {
  713                         vfslocked = VFS_LOCK_GIANT(vp->v_mount);
  714                         while (vrele_count-- > 0)
  715                                 vrele(vp);
  716                         VFS_UNLOCK_GIANT(vfslocked);
  717                 }
  718                 goto done;
  719         }
  720         /*
  721          * do it
  722          */
  723         sx_slock(&proctree_lock);
  724         if (uap->pid < 0) {
  725                 /*
  726                  * by process group
  727                  */
  728                 pg = pgfind(-uap->pid);
  729                 if (pg == NULL) {
  730                         sx_sunlock(&proctree_lock);
  731                         error = ESRCH;
  732                         goto done;
  733                 }
  734                 /*
  735                  * ktrops() may call vrele(). Lock pg_members
  736                  * by the proctree_lock rather than pg_mtx.
  737                  */
  738                 PGRP_UNLOCK(pg);
  739                 nfound = 0;
  740                 LIST_FOREACH(p, &pg->pg_members, p_pglist) {
  741                         PROC_LOCK(p);
  742                         if (p_cansee(td, p) != 0) {
  743                                 PROC_UNLOCK(p); 
  744                                 continue;
  745                         }
  746                         PROC_UNLOCK(p); 
  747                         nfound++;
  748                         if (descend)
  749                                 ret |= ktrsetchildren(td, p, ops, facs, vp);
  750                         else
  751                                 ret |= ktrops(td, p, ops, facs, vp);
  752                 }
  753                 if (nfound == 0) {
  754                         sx_sunlock(&proctree_lock);
  755                         error = ESRCH;
  756                         goto done;
  757                 }
  758         } else {
  759                 /*
  760                  * by pid
  761                  */
  762                 p = pfind(uap->pid);
  763                 if (p == NULL) {
  764                         sx_sunlock(&proctree_lock);
  765                         error = ESRCH;
  766                         goto done;
  767                 }
  768                 error = p_cansee(td, p);
  769                 /*
  770                  * The slock of the proctree lock will keep this process
  771                  * from going away, so unlocking the proc here is ok.
  772                  */
  773                 PROC_UNLOCK(p);
  774                 if (error) {
  775                         sx_sunlock(&proctree_lock);
  776                         goto done;
  777                 }
  778                 if (descend)
  779                         ret |= ktrsetchildren(td, p, ops, facs, vp);
  780                 else
  781                         ret |= ktrops(td, p, ops, facs, vp);
  782         }
  783         sx_sunlock(&proctree_lock);
  784         if (!ret)
  785                 error = EPERM;
  786 done:
  787         if (vp != NULL) {
  788                 vfslocked = VFS_LOCK_GIANT(vp->v_mount);
  789                 (void) vn_close(vp, FWRITE, td->td_ucred, td);
  790                 VFS_UNLOCK_GIANT(vfslocked);
  791         }
  792         ktrace_exit(td);
  793         return (error);
  794 #else /* !KTRACE */
  795         return (ENOSYS);
  796 #endif /* KTRACE */
  797 }
  798 
  799 /* ARGSUSED */
  800 int
  801 utrace(td, uap)
  802         struct thread *td;
  803         register struct utrace_args *uap;
  804 {
  805 
  806 #ifdef KTRACE
  807         struct ktr_request *req;
  808         void *cp;
  809         int error;
  810 
  811         if (!KTRPOINT(td, KTR_USER))
  812                 return (0);
  813         if (uap->len > KTR_USER_MAXLEN)
  814                 return (EINVAL);
  815         cp = malloc(uap->len, M_KTRACE, M_WAITOK);
  816         error = copyin(uap->addr, cp, uap->len);
  817         if (error) {
  818                 free(cp, M_KTRACE);
  819                 return (error);
  820         }
  821         req = ktr_getrequest(KTR_USER);
  822         if (req == NULL) {
  823                 free(cp, M_KTRACE);
  824                 return (ENOMEM);
  825         }
  826         req->ktr_buffer = cp;
  827         req->ktr_header.ktr_len = uap->len;
  828         ktr_submitrequest(td, req);
  829         return (0);
  830 #else /* !KTRACE */
  831         return (ENOSYS);
  832 #endif /* KTRACE */
  833 }
  834 
  835 #ifdef KTRACE
  836 static int
  837 ktrops(td, p, ops, facs, vp)
  838         struct thread *td;
  839         struct proc *p;
  840         int ops, facs;
  841         struct vnode *vp;
  842 {
  843         struct vnode *tracevp = NULL;
  844         struct ucred *tracecred = NULL;
  845 
  846         PROC_LOCK(p);
  847         if (!ktrcanset(td, p)) {
  848                 PROC_UNLOCK(p);
  849                 return (0);
  850         }
  851         mtx_lock(&ktrace_mtx);
  852         if (ops == KTROP_SET) {
  853                 if (p->p_tracevp != vp) {
  854                         /*
  855                          * if trace file already in use, relinquish below
  856                          */
  857                         tracevp = p->p_tracevp;
  858                         VREF(vp);
  859                         p->p_tracevp = vp;
  860                 }
  861                 if (p->p_tracecred != td->td_ucred) {
  862                         tracecred = p->p_tracecred;
  863                         p->p_tracecred = crhold(td->td_ucred);
  864                 }
  865                 p->p_traceflag |= facs;
  866                 if (priv_check(td, PRIV_KTRACE) == 0)
  867                         p->p_traceflag |= KTRFAC_ROOT;
  868         } else {
  869                 /* KTROP_CLEAR */
  870                 if (((p->p_traceflag &= ~facs) & KTRFAC_MASK) == 0) {
  871                         /* no more tracing */
  872                         p->p_traceflag = 0;
  873                         tracevp = p->p_tracevp;
  874                         p->p_tracevp = NULL;
  875                         tracecred = p->p_tracecred;
  876                         p->p_tracecred = NULL;
  877                 }
  878         }
  879         mtx_unlock(&ktrace_mtx);
  880         PROC_UNLOCK(p);
  881         if (tracevp != NULL) {
  882                 int vfslocked;
  883 
  884                 vfslocked = VFS_LOCK_GIANT(tracevp->v_mount);
  885                 vrele(tracevp);
  886                 VFS_UNLOCK_GIANT(vfslocked);
  887         }
  888         if (tracecred != NULL)
  889                 crfree(tracecred);
  890 
  891         return (1);
  892 }
  893 
  894 static int
  895 ktrsetchildren(td, top, ops, facs, vp)
  896         struct thread *td;
  897         struct proc *top;
  898         int ops, facs;
  899         struct vnode *vp;
  900 {
  901         register struct proc *p;
  902         register int ret = 0;
  903 
  904         p = top;
  905         sx_assert(&proctree_lock, SX_LOCKED);
  906         for (;;) {
  907                 ret |= ktrops(td, p, ops, facs, vp);
  908                 /*
  909                  * If this process has children, descend to them next,
  910                  * otherwise do any siblings, and if done with this level,
  911                  * follow back up the tree (but not past top).
  912                  */
  913                 if (!LIST_EMPTY(&p->p_children))
  914                         p = LIST_FIRST(&p->p_children);
  915                 else for (;;) {
  916                         if (p == top)
  917                                 return (ret);
  918                         if (LIST_NEXT(p, p_sibling)) {
  919                                 p = LIST_NEXT(p, p_sibling);
  920                                 break;
  921                         }
  922                         p = p->p_pptr;
  923                 }
  924         }
  925         /*NOTREACHED*/
  926 }
  927 
  928 static void
  929 ktr_writerequest(struct thread *td, struct ktr_request *req)
  930 {
  931         struct ktr_header *kth;
  932         struct vnode *vp;
  933         struct proc *p;
  934         struct ucred *cred;
  935         struct uio auio;
  936         struct iovec aiov[3];
  937         struct mount *mp;
  938         int datalen, buflen, vrele_count;
  939         int error, vfslocked;
  940 
  941         /*
  942          * We hold the vnode and credential for use in I/O in case ktrace is
  943          * disabled on the process as we write out the request.
  944          *
  945          * XXXRW: This is not ideal: we could end up performing a write after
  946          * the vnode has been closed.
  947          */
  948         mtx_lock(&ktrace_mtx);
  949         vp = td->td_proc->p_tracevp;
  950         cred = td->td_proc->p_tracecred;
  951 
  952         /*
  953          * If vp is NULL, the vp has been cleared out from under this
  954          * request, so just drop it.  Make sure the credential and vnode are
  955          * in sync: we should have both or neither.
  956          */
  957         if (vp == NULL) {
  958                 KASSERT(cred == NULL, ("ktr_writerequest: cred != NULL"));
  959                 mtx_unlock(&ktrace_mtx);
  960                 return;
  961         }
  962         VREF(vp);
  963         KASSERT(cred != NULL, ("ktr_writerequest: cred == NULL"));
  964         crhold(cred);
  965         mtx_unlock(&ktrace_mtx);
  966 
  967         kth = &req->ktr_header;
  968         KASSERT(((u_short)kth->ktr_type & ~KTR_DROP) <
  969             sizeof(data_lengths) / sizeof(data_lengths[0]),
  970             ("data_lengths array overflow"));
  971         datalen = data_lengths[(u_short)kth->ktr_type & ~KTR_DROP];
  972         buflen = kth->ktr_len;
  973         auio.uio_iov = &aiov[0];
  974         auio.uio_offset = 0;
  975         auio.uio_segflg = UIO_SYSSPACE;
  976         auio.uio_rw = UIO_WRITE;
  977         aiov[0].iov_base = (caddr_t)kth;
  978         aiov[0].iov_len = sizeof(struct ktr_header);
  979         auio.uio_resid = sizeof(struct ktr_header);
  980         auio.uio_iovcnt = 1;
  981         auio.uio_td = td;
  982         if (datalen != 0) {
  983                 aiov[1].iov_base = (caddr_t)&req->ktr_data;
  984                 aiov[1].iov_len = datalen;
  985                 auio.uio_resid += datalen;
  986                 auio.uio_iovcnt++;
  987                 kth->ktr_len += datalen;
  988         }
  989         if (buflen != 0) {
  990                 KASSERT(req->ktr_buffer != NULL, ("ktrace: nothing to write"));
  991                 aiov[auio.uio_iovcnt].iov_base = req->ktr_buffer;
  992                 aiov[auio.uio_iovcnt].iov_len = buflen;
  993                 auio.uio_resid += buflen;
  994                 auio.uio_iovcnt++;
  995         }
  996 
  997         vfslocked = VFS_LOCK_GIANT(vp->v_mount);
  998         vn_start_write(vp, &mp, V_WAIT);
  999         vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
 1000         (void)VOP_LEASE(vp, td, cred, LEASE_WRITE);
 1001 #ifdef MAC
 1002         error = mac_check_vnode_write(cred, NOCRED, vp);
 1003         if (error == 0)
 1004 #endif
 1005                 error = VOP_WRITE(vp, &auio, IO_UNIT | IO_APPEND, cred);
 1006         VOP_UNLOCK(vp, 0, td);
 1007         vn_finished_write(mp);
 1008         crfree(cred);
 1009         if (!error) {
 1010                 vrele(vp);
 1011                 VFS_UNLOCK_GIANT(vfslocked);
 1012                 return;
 1013         }
 1014         VFS_UNLOCK_GIANT(vfslocked);
 1015 
 1016         /*
 1017          * If error encountered, give up tracing on this vnode.  We defer
 1018          * all the vrele()'s on the vnode until after we are finished walking
 1019          * the various lists to avoid needlessly holding locks.
 1020          * NB: at this point we still hold the vnode reference that must
 1021          * not go away as we need the valid vnode to compare with. Thus let
 1022          * vrele_count start at 1 and the reference will be freed
 1023          * by the loop at the end after our last use of vp.
 1024          */
 1025         log(LOG_NOTICE, "ktrace write failed, errno %d, tracing stopped\n",
 1026             error);
 1027         vrele_count = 1;
 1028         /*
 1029          * First, clear this vnode from being used by any processes in the
 1030          * system.
 1031          * XXX - If one process gets an EPERM writing to the vnode, should
 1032          * we really do this?  Other processes might have suitable
 1033          * credentials for the operation.
 1034          */
 1035         cred = NULL;
 1036         sx_slock(&allproc_lock);
 1037         FOREACH_PROC_IN_SYSTEM(p) {
 1038                 PROC_LOCK(p);
 1039                 if (p->p_tracevp == vp) {
 1040                         mtx_lock(&ktrace_mtx);
 1041                         p->p_tracevp = NULL;
 1042                         p->p_traceflag = 0;
 1043                         cred = p->p_tracecred;
 1044                         p->p_tracecred = NULL;
 1045                         mtx_unlock(&ktrace_mtx);
 1046                         vrele_count++;
 1047                 }
 1048                 PROC_UNLOCK(p);
 1049                 if (cred != NULL) {
 1050                         crfree(cred);
 1051                         cred = NULL;
 1052                 }
 1053         }
 1054         sx_sunlock(&allproc_lock);
 1055 
 1056         /*
 1057          * We can't clear any pending requests in threads that have cached
 1058          * them but not yet committed them, as those are per-thread.  The
 1059          * thread will have to clear it itself on system call return.
 1060          */
 1061         vfslocked = VFS_LOCK_GIANT(vp->v_mount);
 1062         while (vrele_count-- > 0)
 1063                 vrele(vp);
 1064         VFS_UNLOCK_GIANT(vfslocked);
 1065 }
 1066 
 1067 /*
 1068  * Return true if caller has permission to set the ktracing state
 1069  * of target.  Essentially, the target can't possess any
 1070  * more permissions than the caller.  KTRFAC_ROOT signifies that
 1071  * root previously set the tracing status on the target process, and
 1072  * so, only root may further change it.
 1073  */
 1074 static int
 1075 ktrcanset(td, targetp)
 1076         struct thread *td;
 1077         struct proc *targetp;
 1078 {
 1079 
 1080         PROC_LOCK_ASSERT(targetp, MA_OWNED);
 1081         if (targetp->p_traceflag & KTRFAC_ROOT &&
 1082             priv_check(td, PRIV_KTRACE))
 1083                 return (0);
 1084 
 1085         if (p_candebug(td, targetp) != 0)
 1086                 return (0);
 1087 
 1088         return (1);
 1089 }
 1090 
 1091 #endif /* KTRACE */
Cache object: 13f51791091e33723862e2393e327401
[ source navigation ] [ diff markup ] [ identifier search ] [ freetext search ] [ file search ] [ list types ] [ track identifier ]
This page is part of the FreeBSD/Linux Linux Kernel Cross-Reference, and was automatically generated using a modified version of the LXR engine.
FreeBSD/Linux Kernel Cross Reference sys/kern/kern_ktrace.c

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