kernel - Major signal path adjustments to fix races, tsleep race fixes, +more
[dragonfly.git] / sys / kern / kern_ktrace.c
CommitLineData
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1/*
2 * Copyright (c) 1989, 1993
3 * The Regents of the University of California. All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. All advertising materials mentioning features or use of this software
14 * must display the following acknowledgement:
15 * This product includes software developed by the University of
16 * California, Berkeley and its contributors.
17 * 4. Neither the name of the University nor the names of its contributors
18 * may be used to endorse or promote products derived from this software
19 * without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 *
33 * @(#)kern_ktrace.c 8.2 (Berkeley) 9/23/93
34 * $FreeBSD: src/sys/kern/kern_ktrace.c,v 1.35.2.6 2002/07/05 22:36:38 darrenr Exp $
9fb04d14 35 * $DragonFly: src/sys/kern/kern_ktrace.c,v 1.30 2008/04/14 12:01:50 dillon Exp $
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36 */
37
38#include "opt_ktrace.h"
39
40#include <sys/param.h>
41#include <sys/systm.h>
42#include <sys/sysproto.h>
43#include <sys/kernel.h>
44#include <sys/proc.h>
45#include <sys/fcntl.h>
46#include <sys/lock.h>
fad57d0e 47#include <sys/nlookup.h>
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48#include <sys/vnode.h>
49#include <sys/ktrace.h>
50#include <sys/malloc.h>
51#include <sys/syslog.h>
52#include <sys/sysent.h>
53
54#include <vm/vm_zone.h>
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55
56#include <sys/mplock2.h>
57
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58static MALLOC_DEFINE(M_KTRACE, "KTRACE", "KTRACE");
59
60#ifdef KTRACE
402ed7e1 61static struct ktr_header *ktrgetheader (int type);
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62static void ktrwrite (struct lwp *, struct ktr_header *, struct uio *);
63static int ktrcanset (struct thread *,struct proc *);
64static int ktrsetchildren (struct thread *,struct proc *,int,int, ktrace_node_t);
65static int ktrops (struct thread *,struct proc *,int,int, ktrace_node_t);
984263bc 66
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67/*
68 * MPSAFE
69 */
984263bc 70static struct ktr_header *
2b9ccab7 71ktrgetheader(int type)
984263bc 72{
1fd87d54 73 struct ktr_header *kth;
984263bc 74 struct proc *p = curproc; /* XXX */
2af36526 75 struct lwp *lp = curthread->td_lwp;
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76
77 MALLOC(kth, struct ktr_header *, sizeof (struct ktr_header),
78 M_KTRACE, M_WAITOK);
79 kth->ktr_type = type;
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80 /* XXX threaded flag is a hack at the moment */
81 kth->ktr_flags = (p->p_nthreads > 1) ? KTRH_THREADED : 0;
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82 microtime(&kth->ktr_time);
83 kth->ktr_pid = p->p_pid;
2af36526 84 kth->ktr_tid = lp->lwp_tid;
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85 bcopy(p->p_comm, kth->ktr_comm, MAXCOMLEN + 1);
86 return (kth);
87}
88
89void
9fb04d14 90ktrsyscall(struct lwp *lp, int code, int narg, register_t args[])
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91{
92 struct ktr_header *kth;
93 struct ktr_syscall *ktp;
a9b80e23 94 int len;
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95 register_t *argp;
96 int i;
97
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98 len = offsetof(struct ktr_syscall, ktr_args) +
99 (narg * sizeof(register_t));
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100
101 /*
102 * Setting the active bit prevents a ktrace recursion from the
103 * ktracing op itself.
104 */
9fb04d14 105 lp->lwp_traceflag |= KTRFAC_ACTIVE;
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106 kth = ktrgetheader(KTR_SYSCALL);
107 MALLOC(ktp, struct ktr_syscall *, len, M_KTRACE, M_WAITOK);
108 ktp->ktr_code = code;
109 ktp->ktr_narg = narg;
110 argp = &ktp->ktr_args[0];
111 for (i = 0; i < narg; i++)
112 *argp++ = args[i];
113 kth->ktr_buf = (caddr_t)ktp;
114 kth->ktr_len = len;
9910d07b 115 ktrwrite(lp, kth, NULL);
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116 FREE(ktp, M_KTRACE);
117 FREE(kth, M_KTRACE);
9fb04d14 118 lp->lwp_traceflag &= ~KTRFAC_ACTIVE;
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119}
120
121void
9fb04d14 122ktrsysret(struct lwp *lp, int code, int error, register_t retval)
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123{
124 struct ktr_header *kth;
125 struct ktr_sysret ktp;
984263bc 126
9fb04d14 127 lp->lwp_traceflag |= KTRFAC_ACTIVE;
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128 kth = ktrgetheader(KTR_SYSRET);
129 ktp.ktr_code = code;
130 ktp.ktr_error = error;
131 ktp.ktr_retval = retval; /* what about val2 ? */
132
133 kth->ktr_buf = (caddr_t)&ktp;
134 kth->ktr_len = sizeof(struct ktr_sysret);
135
9910d07b 136 ktrwrite(lp, kth, NULL);
984263bc 137 FREE(kth, M_KTRACE);
9fb04d14 138 lp->lwp_traceflag &= ~KTRFAC_ACTIVE;
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139}
140
141void
9fb04d14 142ktrnamei(struct lwp *lp, char *path)
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143{
144 struct ktr_header *kth;
984263bc 145
9fb04d14 146 lp->lwp_traceflag |= KTRFAC_ACTIVE;
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147 kth = ktrgetheader(KTR_NAMEI);
148 kth->ktr_len = strlen(path);
149 kth->ktr_buf = path;
150
9910d07b 151 ktrwrite(lp, kth, NULL);
984263bc 152 FREE(kth, M_KTRACE);
9fb04d14 153 lp->lwp_traceflag &= ~KTRFAC_ACTIVE;
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154}
155
156void
9fb04d14 157ktrgenio(struct lwp *lp, int fd, enum uio_rw rw, struct uio *uio, int error)
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158{
159 struct ktr_header *kth;
160 struct ktr_genio ktg;
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161
162 if (error)
163 return;
9fb04d14 164 lp->lwp_traceflag |= KTRFAC_ACTIVE;
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165 kth = ktrgetheader(KTR_GENIO);
166 ktg.ktr_fd = fd;
167 ktg.ktr_rw = rw;
168 kth->ktr_buf = (caddr_t)&ktg;
169 kth->ktr_len = sizeof(struct ktr_genio);
170 uio->uio_offset = 0;
171 uio->uio_rw = UIO_WRITE;
172
9910d07b 173 ktrwrite(lp, kth, uio);
984263bc 174 FREE(kth, M_KTRACE);
9fb04d14 175 lp->lwp_traceflag &= ~KTRFAC_ACTIVE;
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176}
177
178void
9fb04d14 179ktrpsig(struct lwp *lp, int sig, sig_t action, sigset_t *mask, int code)
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180{
181 struct ktr_header *kth;
182 struct ktr_psig kp;
984263bc 183
9fb04d14 184 lp->lwp_traceflag |= KTRFAC_ACTIVE;
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185 kth = ktrgetheader(KTR_PSIG);
186 kp.signo = (char)sig;
187 kp.action = action;
188 kp.mask = *mask;
189 kp.code = code;
190 kth->ktr_buf = (caddr_t)&kp;
191 kth->ktr_len = sizeof (struct ktr_psig);
192
9910d07b 193 ktrwrite(lp, kth, NULL);
984263bc 194 FREE(kth, M_KTRACE);
9fb04d14 195 lp->lwp_traceflag &= ~KTRFAC_ACTIVE;
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196}
197
198void
9fb04d14 199ktrcsw(struct lwp *lp, int out, int user)
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200{
201 struct ktr_header *kth;
202 struct ktr_csw kc;
984263bc 203
9fb04d14 204 lp->lwp_traceflag |= KTRFAC_ACTIVE;
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205 kth = ktrgetheader(KTR_CSW);
206 kc.out = out;
207 kc.user = user;
208 kth->ktr_buf = (caddr_t)&kc;
209 kth->ktr_len = sizeof (struct ktr_csw);
210
9910d07b 211 ktrwrite(lp, kth, NULL);
984263bc 212 FREE(kth, M_KTRACE);
9fb04d14 213 lp->lwp_traceflag &= ~KTRFAC_ACTIVE;
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214}
215#endif
216
217/* Interface and common routines */
218
0e5797fe 219#ifdef KTRACE
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220/*
221 * ktrace system call
222 */
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223struct ktrace_clear_info {
224 ktrace_node_t tracenode;
225 int rootclear;
226 int error;
227};
228
229static int ktrace_clear_callback(struct proc *p, void *data);
230
231#endif
232
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233/*
234 * MPALMOSTSAFE
235 */
984263bc 236int
753fd850 237sys_ktrace(struct ktrace_args *uap)
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238{
239#ifdef KTRACE
0e5797fe 240 struct ktrace_clear_info info;
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241 struct thread *td = curthread;
242 struct proc *curp = td->td_proc;
41c20dac 243 struct proc *p;
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244 struct pgrp *pg;
245 int facs = uap->facs & ~KTRFAC_ROOT;
246 int ops = KTROP(uap->ops);
247 int descend = uap->ops & KTRFLAG_DESCEND;
248 int ret = 0;
249 int error = 0;
fad57d0e 250 struct nlookupdata nd;
29f58392 251 ktrace_node_t tracenode = NULL;
984263bc 252
3919ced0 253 get_mplock();
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254 curp->p_traceflag |= KTRFAC_ACTIVE;
255 if (ops != KTROP_CLEAR) {
256 /*
257 * an operation which requires a file argument.
258 */
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259 error = nlookup_init(&nd, uap->fname,
260 UIO_USERSPACE, NLC_LOCKVP);
261 if (error == 0)
262 error = vn_open(&nd, NULL, FREAD|FWRITE|O_NOFOLLOW, 0);
263 if (error == 0 && nd.nl_open_vp->v_type != VREG)
264 error = EACCES;
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265 if (error) {
266 curp->p_traceflag &= ~KTRFAC_ACTIVE;
fad57d0e 267 nlookup_done(&nd);
3919ced0 268 goto done;
984263bc 269 }
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270 MALLOC(tracenode, ktrace_node_t, sizeof (struct ktrace_node),
271 M_KTRACE, M_WAITOK | M_ZERO);
272 tracenode->kn_vp = nd.nl_open_vp;
273 tracenode->kn_refs = 1;
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274 nd.nl_open_vp = NULL;
275 nlookup_done(&nd);
a11aaa81 276 vn_unlock(tracenode->kn_vp);
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277 }
278 /*
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279 * Clear all uses of the tracefile. Not the most efficient operation
280 * in the world.
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281 */
282 if (ops == KTROP_CLEARFILE) {
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283 info.tracenode = tracenode;
284 info.error = 0;
285 info.rootclear = 0;
286 allproc_scan(ktrace_clear_callback, &info);
287 error = info.error;
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288 goto done;
289 }
290 /*
291 * need something to (un)trace (XXX - why is this here?)
292 */
293 if (!facs) {
294 error = EINVAL;
295 goto done;
296 }
297 /*
298 * do it
299 */
300 if (uap->pid < 0) {
301 /*
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302 * By process group. Process group is referenced, preventing
303 * disposal.
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304 */
305 pg = pgfind(-uap->pid);
306 if (pg == NULL) {
307 error = ESRCH;
308 goto done;
309 }
58c2553a 310 lwkt_gettoken(&pg->pg_token);
fad57d0e 311 LIST_FOREACH(p, &pg->pg_members, p_pglist) {
58c2553a 312 PHOLD(p);
984263bc 313 if (descend)
9910d07b 314 ret |= ktrsetchildren(td, p, ops, facs, tracenode);
984263bc 315 else
9910d07b 316 ret |= ktrops(td, p, ops, facs, tracenode);
58c2553a 317 PRELE(p);
fad57d0e 318 }
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319 lwkt_reltoken(&pg->pg_token);
320 pgrel(pg);
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321 } else {
322 /*
323 * by pid
324 */
325 p = pfind(uap->pid);
326 if (p == NULL) {
327 error = ESRCH;
328 goto done;
329 }
330 if (descend)
9910d07b 331 ret |= ktrsetchildren(td, p, ops, facs, tracenode);
984263bc 332 else
9910d07b 333 ret |= ktrops(td, p, ops, facs, tracenode);
58c2553a 334 PRELE(p);
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335 }
336 if (!ret)
337 error = EPERM;
338done:
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339 if (tracenode)
340 ktrdestroy(&tracenode);
984263bc 341 curp->p_traceflag &= ~KTRFAC_ACTIVE;
3919ced0 342 rel_mplock();
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343 return (error);
344#else
345 return ENOSYS;
346#endif
347}
348
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349#ifdef KTRACE
350
351/*
352 * NOTE: NOT MPSAFE (yet)
353 */
354static int
355ktrace_clear_callback(struct proc *p, void *data)
356{
357 struct ktrace_clear_info *info = data;
358
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359 if (p->p_tracenode) {
360 if (info->rootclear) {
361 if (p->p_tracenode == info->tracenode) {
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362 ktrdestroy(&p->p_tracenode);
363 p->p_traceflag = 0;
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MD
364 }
365 } else {
366 if (p->p_tracenode->kn_vp == info->tracenode->kn_vp) {
9910d07b 367 if (ktrcanset(curthread, p)) {
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MD
368 ktrdestroy(&p->p_tracenode);
369 p->p_traceflag = 0;
370 } else {
371 info->error = EPERM;
372 }
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373 }
374 }
375 }
376 return(0);
377}
378
379#endif
380
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381/*
382 * utrace system call
3919ced0
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383 *
384 * MPALMOSTSAFE
984263bc 385 */
984263bc 386int
753fd850 387sys_utrace(struct utrace_args *uap)
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388{
389#ifdef KTRACE
390 struct ktr_header *kth;
dadab5e9 391 struct thread *td = curthread; /* XXX */
1fd87d54 392 caddr_t cp;
984263bc 393
dadab5e9 394 if (!KTRPOINT(td, KTR_USER))
984263bc 395 return (0);
ab2eb4eb 396 if (uap->len > KTR_USER_MAXLEN)
984263bc 397 return (EINVAL);
9fb04d14 398 td->td_lwp->lwp_traceflag |= KTRFAC_ACTIVE;
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MD
399 kth = ktrgetheader(KTR_USER);
400 MALLOC(cp, caddr_t, uap->len, M_KTRACE, M_WAITOK);
401 if (!copyin(uap->addr, cp, uap->len)) {
402 kth->ktr_buf = cp;
403 kth->ktr_len = uap->len;
9910d07b 404 ktrwrite(td->td_lwp, kth, NULL);
984263bc 405 }
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406 FREE(kth, M_KTRACE);
407 FREE(cp, M_KTRACE);
9fb04d14 408 td->td_lwp->lwp_traceflag &= ~KTRFAC_ACTIVE;
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409
410 return (0);
411#else
412 return (ENOSYS);
413#endif
414}
415
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416void
417ktrdestroy(struct ktrace_node **tracenodep)
418{
419 ktrace_node_t tracenode;
420
421 if ((tracenode = *tracenodep) != NULL) {
422 *tracenodep = NULL;
423 KKASSERT(tracenode->kn_refs > 0);
b5c4d81f 424 if (atomic_fetchadd_int(&tracenode->kn_refs, -1) == 1) {
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425 vn_close(tracenode->kn_vp, FREAD|FWRITE);
426 tracenode->kn_vp = NULL;
427 FREE(tracenode, M_KTRACE);
428 }
429 }
430}
431
0e5797fe
MD
432/*
433 * This allows a process to inherit a ref on a tracenode and is also used
434 * as a temporary ref to prevent a tracenode from being destroyed out from
435 * under an active operation.
436 */
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437ktrace_node_t
438ktrinherit(ktrace_node_t tracenode)
439{
8a1a197f
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440 if (tracenode) {
441 KKASSERT(tracenode->kn_refs > 0);
b5c4d81f 442 atomic_add_int(&tracenode->kn_refs, 1);
8a1a197f 443 }
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444 return(tracenode);
445}
446
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447#ifdef KTRACE
448static int
9910d07b 449ktrops(struct thread *td, struct proc *p, int ops, int facs,
29f58392 450 ktrace_node_t tracenode)
984263bc 451{
29f58392 452 ktrace_node_t oldnode;
984263bc 453
9910d07b 454 if (!ktrcanset(td, p))
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455 return (0);
456 if (ops == KTROP_SET) {
8a1a197f 457 if ((oldnode = p->p_tracenode) != tracenode) {
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458 p->p_tracenode = ktrinherit(tracenode);
459 ktrdestroy(&oldnode);
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460 }
461 p->p_traceflag |= facs;
9910d07b 462 if (td->td_ucred->cr_uid == 0)
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463 p->p_traceflag |= KTRFAC_ROOT;
464 } else {
465 /* KTROP_CLEAR */
466 if (((p->p_traceflag &= ~facs) & KTRFAC_MASK) == 0) {
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467 /* no more tracing */
468 p->p_traceflag = 0;
29f58392 469 ktrdestroy(&p->p_tracenode);
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470 }
471 }
472
473 return (1);
474}
475
476static int
9910d07b 477ktrsetchildren(struct thread *td, struct proc *top, int ops, int facs,
29f58392 478 ktrace_node_t tracenode)
984263bc 479{
1fd87d54 480 struct proc *p;
b5c4d81f 481 struct proc *np;
1fd87d54 482 int ret = 0;
984263bc 483
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MD
484 p = top;
485 PHOLD(p);
486 lwkt_gettoken(&p->p_token);
b5c4d81f 487
3f1815ac 488 for (;;) {
9910d07b 489 ret |= ktrops(td, p, ops, facs, tracenode);
b5c4d81f 490
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491 /*
492 * If this process has children, descend to them next,
493 * otherwise do any siblings, and if done with this level,
494 * follow back up the tree (but not past top).
495 */
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MD
496 if ((np = LIST_FIRST(&p->p_children)) != NULL) {
497 PHOLD(np);
984263bc 498 }
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MD
499 while (np == NULL) {
500 if (p == top)
501 break;
502 if ((np = LIST_NEXT(p, p_sibling)) != NULL) {
503 PHOLD(np);
504 break;
505 }
506
507 /*
508 * recurse up to parent, set p in our inner
509 * loop when doing this. np can be NULL if
510 * we race a reparenting to init (thus 'top'
511 * is skipped past and never encountered).
512 */
513 np = p->p_pptr;
514 if (np == NULL)
515 break;
b5c4d81f 516 PHOLD(np);
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517 lwkt_reltoken(&p->p_token);
518 PRELE(p);
519 p = np;
520 lwkt_gettoken(&p->p_token);
521 np = NULL;
522 }
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523 lwkt_reltoken(&p->p_token);
524 PRELE(p);
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525 p = np;
526 if (p == NULL)
527 break;
528 /* Already held, but we need the token too */
529 lwkt_gettoken(&p->p_token);
984263bc 530 }
b5c4d81f 531 return (ret);
984263bc
MD
532}
533
534static void
9910d07b 535ktrwrite(struct lwp *lp, struct ktr_header *kth, struct uio *uio)
984263bc 536{
0e5797fe 537 struct ktrace_clear_info info;
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MD
538 struct uio auio;
539 struct iovec aiov[2];
984263bc 540 int error;
29f58392 541 ktrace_node_t tracenode;
984263bc 542
d681a0bb 543 /*
29f58392
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544 * We have to ref our tracenode to prevent it from being ripped out
545 * from under us while we are trying to use it. p_tracenode can
546 * go away at any time if another process gets a write error.
a9b80e23
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547 *
548 * XXX not MP safe
d681a0bb 549 */
9910d07b 550 if (lp->lwp_proc->p_tracenode == NULL)
984263bc 551 return;
9910d07b 552 tracenode = ktrinherit(lp->lwp_proc->p_tracenode);
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MD
553 auio.uio_iov = &aiov[0];
554 auio.uio_offset = 0;
555 auio.uio_segflg = UIO_SYSSPACE;
556 auio.uio_rw = UIO_WRITE;
557 aiov[0].iov_base = (caddr_t)kth;
558 aiov[0].iov_len = sizeof(struct ktr_header);
559 auio.uio_resid = sizeof(struct ktr_header);
560 auio.uio_iovcnt = 1;
dadab5e9 561 auio.uio_td = curthread;
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MD
562 if (kth->ktr_len > 0) {
563 auio.uio_iovcnt++;
564 aiov[1].iov_base = kth->ktr_buf;
565 aiov[1].iov_len = kth->ktr_len;
566 auio.uio_resid += kth->ktr_len;
567 if (uio != NULL)
568 kth->ktr_len += uio->uio_resid;
569 }
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MD
570 vn_lock(tracenode->kn_vp, LK_EXCLUSIVE | LK_RETRY);
571 error = VOP_WRITE(tracenode->kn_vp, &auio,
9910d07b 572 IO_UNIT | IO_APPEND, lp->lwp_thread->td_ucred);
984263bc 573 if (error == 0 && uio != NULL) {
29f58392 574 error = VOP_WRITE(tracenode->kn_vp, uio,
9910d07b 575 IO_UNIT | IO_APPEND, lp->lwp_thread->td_ucred);
984263bc 576 }
a11aaa81 577 vn_unlock(tracenode->kn_vp);
8a1a197f
MD
578 if (error) {
579 /*
580 * If an error occured, give up tracing on all processes
581 * using this tracenode. This is not MP safe but is
582 * blocking-safe.
583 */
584 log(LOG_NOTICE,
585 "ktrace write failed, errno %d, tracing stopped\n", error);
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586 info.tracenode = tracenode;
587 info.error = 0;
588 info.rootclear = 1;
589 allproc_scan(ktrace_clear_callback, &info);
984263bc 590 }
29f58392 591 ktrdestroy(&tracenode);
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592}
593
594/*
595 * Return true if caller has permission to set the ktracing state
596 * of target. Essentially, the target can't possess any
597 * more permissions than the caller. KTRFAC_ROOT signifies that
598 * root previously set the tracing status on the target process, and
599 * so, only root may further change it.
600 *
601 * TODO: check groups. use caller effective gid.
602 */
603static int
9910d07b 604ktrcanset(struct thread *calltd, struct proc *targetp)
984263bc 605{
9910d07b 606 struct ucred *caller = calltd->td_ucred;
41c20dac 607 struct ucred *target = targetp->p_ucred;
984263bc 608
41c20dac 609 if (!PRISON_CHECK(caller, target))
984263bc 610 return (0);
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611 if ((caller->cr_uid == target->cr_ruid &&
612 target->cr_ruid == target->cr_svuid &&
613 caller->cr_rgid == target->cr_rgid && /* XXX */
614 target->cr_rgid == target->cr_svgid &&
984263bc 615 (targetp->p_traceflag & KTRFAC_ROOT) == 0 &&
4643740a 616 (targetp->p_flags & P_SUGID) == 0) ||
41c20dac 617 caller->cr_uid == 0)
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618 return (1);
619
620 return (0);
621}
622
623#endif /* KTRACE */