xref: /dragonfly/sys/kern/kern_checkpoint.c (revision 509221ae) 
1 /*-
2  * Copyright (c) 2003 Kip Macy
3  * 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  *
14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24  * SUCH DAMAGE.
25  *
26  * $DragonFly: src/sys/kern/kern_checkpoint.c,v 1.4 2005/07/06 05:59:39 dillon Exp $
27  */
28 
29 #include <sys/types.h>
30 #include <sys/param.h>
31 #include <sys/proc.h>
32 #include <sys/module.h>
33 #include <sys/sysent.h>
34 #include <sys/kernel.h>
35 #include <sys/systm.h>
36 #include <sys/nlookup.h>
37 
38 #include <sys/file.h>
39 /* only on dragonfly */
40 #include <sys/file2.h>
41 #include <sys/fcntl.h>
42 #include <sys/signal.h>
43 #include <vm/vm_param.h>
44 #include <vm/vm.h>
45 #include <sys/imgact_elf.h>
46 #include <sys/procfs.h>
47 
48 #include <sys/lock.h>
49 #include <vm/pmap.h>
50 #include <vm/vm_map.h>
51 #include <vm/vm_extern.h>
52 #include <sys/mman.h>
53 #include <sys/sysent.h>
54 #include <sys/sysproto.h>
55 #include <sys/resource.h>
56 #include <sys/resourcevar.h>
57 #include <sys/malloc.h>
58 #include <sys/stat.h>
59 #include <sys/uio.h>
60 #include <sys/namei.h>
61 #include <sys/vnode.h>
62 #include <machine/limits.h>
63 #include <i386/include/frame.h>
64 #include <sys/signalvar.h>
65 #include <sys/syslog.h>
66 #include <sys/sysctl.h>
67 #include <i386/include/sigframe.h>
68 #include <sys/exec.h>
69 #include <sys/unistd.h>
70 #include <sys/time.h>
71 #include <sys/kern_syscall.h>
72 #include <sys/checkpoint.h>
73 #include <sys/mount.h>
74 #include <sys/ckpt.h>
75 
76 
77 static int elf_loadphdrs(struct file *fp,  Elf_Phdr *phdr, int numsegs);
78 static int elf_getnotes(struct proc *p, struct file *fp, size_t notesz);
79 static int elf_demarshalnotes(void *src, prpsinfo_t *psinfo,
80 		 prstatus_t *status, prfpregset_t *fpregset, int nthreads);
81 static int elf_loadnotes(struct proc *, prpsinfo_t *, prstatus_t *,
82 		 prfpregset_t *);
83 static int elf_getsigs(struct proc *p, struct file *fp);
84 static int elf_getfiles(struct proc *p, struct file *fp);
85 static int elf_gettextvp(struct proc *p, struct file *fp);
86 static char *ckpt_expand_name(const char *name, uid_t uid, pid_t pid);
87 
88 static int ckptgroup = 0;       /* wheel only, -1 for any group */
89 SYSCTL_INT(_kern, OID_AUTO, ckptgroup, CTLFLAG_RW, &ckptgroup, 0, "");
90 
91 /* ref count to see how many processes that are being checkpointed */
92 static int chptinuse = 0;
93 
94 static __inline
95 int
96 read_check(struct file *fp, void *buf, size_t nbyte)
97 {
98 	size_t nread;
99 	int error;
100 
101         PRINTF(("reading %d bytes\n", nbyte));
102 	error = fp_read(fp, buf, nbyte, &nread, 1);
103 	if (error) {
104                 PRINTF(("read failed - %d", error));
105 	} else if (nread != nbyte) {
106                 PRINTF(("wanted to read %d - read %d\n", nbyte, nread));
107 		error = EINVAL;
108 	}
109 	return error;
110 }
111 
112 static int
113 elf_gethdr(struct file *fp, Elf_Ehdr *ehdr)
114 {
115 	size_t nbyte = sizeof(Elf_Ehdr);
116 	int error;
117 
118 	if ((error = read_check(fp, ehdr, nbyte)) != 0)
119 		goto done;
120 	if (!(ehdr->e_ehsize == sizeof(Elf_Ehdr))) {
121 		PRINTF(("wrong elf header size: %d\n"
122 		       "expected size        : %d\n",
123 		       ehdr->e_ehsize, sizeof(Elf_Ehdr)));
124 		return EINVAL;
125 	}
126 	if (!(ehdr->e_phentsize == sizeof(Elf_Phdr))) {
127 		PRINTF(("wrong program header size: %d\n"
128 		       "expected size            : %d\n",
129 		       ehdr->e_phentsize, sizeof(Elf_Phdr)));
130 		return EINVAL;
131 	}
132 
133 	if (!(ehdr->e_ident[EI_MAG0] == ELFMAG0 &&
134 	      ehdr->e_ident[EI_MAG1] == ELFMAG1 &&
135 	      ehdr->e_ident[EI_MAG2] == ELFMAG2 &&
136 	      ehdr->e_ident[EI_MAG3] == ELFMAG3 &&
137 	      ehdr->e_ident[EI_CLASS] == ELF_CLASS &&
138 	      ehdr->e_ident[EI_DATA] == ELF_DATA &&
139 	      ehdr->e_ident[EI_VERSION] == EV_CURRENT &&
140 	      ehdr->e_ident[EI_OSABI] == ELFOSABI_FREEBSD &&
141 	      ehdr->e_ident[EI_ABIVERSION] == 0)) {
142 		PRINTF(("bad elf header\n there are %d segments\n",
143 		       ehdr->e_phnum));
144 		return EINVAL;
145 
146 	}
147 	PRINTF(("Elf header size:           %d\n", ehdr->e_ehsize));
148 	PRINTF(("Program header size:       %d\n", ehdr->e_phentsize));
149 	PRINTF(("Number of Program headers: %d\n", ehdr->e_phnum));
150  done:
151 	return error;
152 }
153 
154 static int
155 elf_getphdrs(struct file *fp, Elf_Phdr *phdr, size_t nbyte)
156 {
157 	int i;
158 	int error;
159 	int nheaders = nbyte/sizeof(Elf_Phdr);
160 
161 	PRINTF(("reading phdrs section\n"));
162 	if ((error = read_check(fp, phdr, nbyte)) != 0)
163 		goto done;
164 	printf("headers section:\n");
165 	for (i = 0; i < nheaders; i++) {
166 		printf("entry type:   %d\n", phdr[i].p_type);
167 		printf("file offset:  %d\n", phdr[i].p_offset);
168 		printf("virt address: %p\n", (uint32_t *)phdr[i].p_vaddr);
169 		printf("file size:    %d\n", phdr[i].p_filesz);
170 		printf("memory size:  %d\n", phdr[i].p_memsz);
171 		printf("\n");
172 	}
173  done:
174 	return error;
175 }
176 
177 
178 static int
179 elf_getnotes(struct proc *p, struct file *fp, size_t notesz)
180 {
181 	int error;
182 	int nthreads;
183 	char *note;
184 	prpsinfo_t *psinfo;
185 	prstatus_t *status;
186 	prfpregset_t *fpregset;
187 
188 	nthreads = (notesz - sizeof(prpsinfo_t))/(sizeof(prstatus_t) +
189 						  sizeof(prfpregset_t));
190 	PRINTF(("reading notes header nthreads=%d\n", nthreads));
191 	if (nthreads <= 0 || nthreads > CKPT_MAXTHREADS)
192 		return EINVAL;
193 
194 	psinfo  = malloc(sizeof(prpsinfo_t), M_TEMP, M_ZERO | M_WAITOK);
195 	status  = malloc(nthreads*sizeof(prstatus_t), M_TEMP, M_WAITOK);
196 	fpregset  = malloc(nthreads*sizeof(prfpregset_t), M_TEMP, M_WAITOK);
197 	note = malloc(notesz, M_TEMP, M_WAITOK);
198 
199 
200 	PRINTF(("reading notes section\n"));
201 	if ((error = read_check(fp, note, notesz)) != 0)
202 		goto done;
203 	error = elf_demarshalnotes(note, psinfo, status, fpregset, nthreads);
204 	if (error)
205 		goto done;
206 	/* fetch register state from notes */
207 	error = elf_loadnotes(p, psinfo, status, fpregset);
208  done:
209 	if (psinfo)
210 		free(psinfo, M_TEMP);
211 	if (status)
212 		free(status, M_TEMP);
213 	if (fpregset)
214 		free(fpregset, M_TEMP);
215 	if (note)
216 		free(note, M_TEMP);
217 	return error;
218 }
219 
220 static int
221 ckpt_thaw_proc(struct proc *p, struct file *fp)
222 {
223 
224 	Elf_Phdr *phdr = NULL;
225 	Elf_Ehdr *ehdr = NULL;
226 	int error;
227 	size_t nbyte;
228 
229 	TRACE_ENTER;
230 
231 	ehdr = malloc(sizeof(Elf_Ehdr), M_TEMP, M_ZERO | M_WAITOK);
232 
233 	if ((error = elf_gethdr(fp, ehdr)) != 0)
234 		goto done;
235 	nbyte = sizeof(Elf_Phdr) * ehdr->e_phnum;
236 	phdr = malloc(nbyte, M_TEMP, M_WAITOK);
237 
238 	/* fetch description of program writable mappings */
239 	if ((error = elf_getphdrs(fp, phdr, nbyte)) != 0)
240 		goto done;
241 
242 	/* fetch notes section containing register state */
243 	if ((error = elf_getnotes(p, fp, phdr->p_filesz)) != 0)
244 		goto done;
245 
246 	/* fetch program text vnodes */
247 	if ((error = elf_gettextvp(p, fp)) != 0)
248 		goto done;
249 
250 	/* fetch signal disposition */
251 	if ((error = elf_getsigs(p, fp)) != 0) {
252 		printf("failure in recovering signals\n");
253 		goto done;
254 	}
255 
256 	/* fetch open files */
257 	if ((error = elf_getfiles(p, fp)) != 0)
258 		goto done;
259 
260 	/* handle mappings last in case we are reading from a socket */
261 	error = elf_loadphdrs(fp, phdr, ehdr->e_phnum);
262 
263 	/*
264 	 * Set the textvp to the checkpoint file and mark the vnode so
265 	 * a future checkpointing of this checkpoint-restored program
266 	 * will copy out the contents of the mappings rather then trying
267 	 * to record the vnode info related to the checkpoint file, which
268 	 * is likely going to be destroyed when the program is re-checkpointed.
269 	 */
270 	if (error == 0 && fp->f_data && fp->f_type == DTYPE_VNODE) {
271 		if (p->p_textvp)
272 			vrele(p->p_textvp);
273 		p->p_textvp = (struct vnode *)fp->f_data;
274 		p->p_textvp->v_flag |= VCKPT;
275 		vref(p->p_textvp);
276 	}
277 done:
278 	if (ehdr)
279 		free(ehdr, M_TEMP);
280 	if (phdr)
281 		free(phdr, M_TEMP);
282 	TRACE_EXIT;
283 	return error;
284 }
285 
286 static int
287 elf_loadnotes(struct proc *p, prpsinfo_t *psinfo, prstatus_t *status,
288 	   prfpregset_t *fpregset)
289 {
290 	int error;
291 
292 	/* validate status and psinfo */
293 	TRACE_ENTER;
294 	if (status->pr_version != PRSTATUS_VERSION ||
295 	    status->pr_statussz != sizeof(prstatus_t) ||
296 	    status->pr_gregsetsz != sizeof(gregset_t) ||
297 	    status->pr_fpregsetsz != sizeof(fpregset_t) ||
298 	    psinfo->pr_version != PRPSINFO_VERSION ||
299 	    psinfo->pr_psinfosz != sizeof(prpsinfo_t)) {
300 	        PRINTF(("status check failed\n"));
301 		error = EINVAL;
302 		goto done;
303 	}
304 	if ((error = set_regs(p, &status->pr_reg)) != 0)
305 		goto done;
306 	error = set_fpregs(p, fpregset);
307 	strlcpy(p->p_comm, psinfo->pr_fname, sizeof(p->p_comm));
308 	/* XXX psinfo->pr_psargs not yet implemented */
309  done:
310 	TRACE_EXIT;
311 	return error;
312 }
313 
314 static int
315 elf_getnote(void *src, size_t *off, const char *name, unsigned int type,
316 	    void **desc, size_t descsz)
317 {
318 	Elf_Note note;
319 	int error;
320 
321 	TRACE_ENTER;
322 	if (src == NULL) {
323 		error = EFAULT;
324 		goto done;
325 	}
326 	bcopy((char *)src + *off, &note, sizeof note);
327 
328 	PRINTF(("at offset: %d expected note of type: %d - got: %d\n",
329 	       *off, type, note.n_type));
330 	*off += sizeof note;
331 	if (type != note.n_type) {
332 		TRACE_ERR;
333 		error = EINVAL;
334 		goto done;
335 	}
336 	if (strncmp(name, (char *) src + *off, note.n_namesz) != 0) {
337 		error = EINVAL;
338 		goto done;
339 	}
340 	*off += roundup2(note.n_namesz, sizeof(Elf_Size));
341 	if (note.n_descsz != descsz) {
342 		TRACE_ERR;
343 		error = EINVAL;
344 		goto done;
345 	}
346 	if (desc)
347 	        bcopy((char *)src + *off, *desc, note.n_descsz);
348 	*off += roundup2(note.n_descsz, sizeof(Elf_Size));
349 	error = 0;
350  done:
351 	TRACE_EXIT;
352 	return error;
353 }
354 
355 static int
356 elf_demarshalnotes(void *src, prpsinfo_t *psinfo, prstatus_t *status,
357 		   prfpregset_t *fpregset, int nthreads)
358 {
359 	int i;
360 	int error;
361 	int off = 0;
362 
363 	TRACE_ENTER;
364 	error = elf_getnote(src, &off, "FreeBSD", NT_PRSTATUS,
365 			   (void **)&status, sizeof(prstatus_t));
366 	if (error)
367 		goto done;
368 	error = elf_getnote(src, &off, "FreeBSD", NT_FPREGSET,
369 			   (void **)&fpregset, sizeof(prfpregset_t));
370 	if (error)
371 		goto done;
372 	error = elf_getnote(src, &off, "FreeBSD", NT_PRPSINFO,
373 			   (void **)&psinfo, sizeof(prpsinfo_t));
374 	if (error)
375 		goto done;
376 
377 	/*
378 	 * The remaining portion needs to be an integer multiple
379 	 * of prstatus_t and prfpregset_t
380 	 */
381 	for (i = 0 ; i < nthreads - 1; i++) {
382 		status++; fpregset++;
383 		error = elf_getnote(src, &off, "FreeBSD", NT_PRSTATUS,
384 				   (void **)&status, sizeof (prstatus_t));
385 		if (error)
386 			goto done;
387 		error = elf_getnote(src, &off, "FreeBSD", NT_FPREGSET,
388 				   (void **)&fpregset, sizeof(prfpregset_t));
389 		if (error)
390 			goto done;
391 	}
392 
393  done:
394 	TRACE_EXIT;
395 	return error;
396 }
397 
398 
399 static int
400 mmap_phdr(struct file *fp, Elf_Phdr *phdr)
401 {
402 	int error;
403 	size_t len;
404 	int prot;
405 	void *addr;
406 	int flags;
407 	off_t pos;
408 
409 	TRACE_ENTER;
410 	pos = phdr->p_offset;
411 	len = phdr->p_filesz;
412 	addr = (void *)phdr->p_vaddr;
413 	flags = MAP_FIXED | MAP_NOSYNC | MAP_PRIVATE;
414 	prot = 0;
415 	if (phdr->p_flags & PF_R)
416 		prot |= PROT_READ;
417 	if (phdr->p_flags & PF_W)
418 		prot |= PROT_WRITE;
419 	if (phdr->p_flags & PF_X)
420 		prot |= PROT_EXEC;
421 	if ((error = fp_mmap(addr, len, prot, flags, fp, pos, &addr)) != 0) {
422 		PRINTF(("mmap failed: %d\n", error);	   );
423 	}
424 	PRINTF(("map @%08x-%08x fileoff %08x-%08x\n", (int)addr, (int)((char *)addr + len), (int)pos, (int)(pos + len)));
425 	TRACE_EXIT;
426 	return error;
427 }
428 
429 
430 static int
431 elf_loadphdrs(struct file *fp, Elf_Phdr *phdr, int numsegs)
432 {
433 	int i;
434 	int error = 0;
435 
436 	TRACE_ENTER;
437 	for (i = 1; i < numsegs; i++)  {
438 		if ((error = mmap_phdr(fp, &phdr[i])) != 0)
439 			break;
440 	}
441 	TRACE_EXIT;
442 	return error;
443 }
444 
445 static int
446 elf_getsigs(struct proc *p, struct file *fp)
447 {
448 	int error;
449 	struct ckpt_siginfo *csi;
450 	struct sigacts *tmpsigacts;
451 
452 	TRACE_ENTER;
453 	csi = malloc(sizeof(struct ckpt_siginfo), M_TEMP, M_ZERO | M_WAITOK);
454 	if ((error = read_check(fp, csi, sizeof(struct ckpt_siginfo))) != 0)
455 		goto done;
456 
457 	if (csi->csi_ckptpisz != sizeof(struct ckpt_siginfo)) {
458 		TRACE_ERR;
459 		error = EINVAL;
460 		goto done;
461 	}
462 	tmpsigacts = p->p_procsig->ps_sigacts;
463 	bcopy(&csi->csi_procsig, p->p_procsig, sizeof(struct procsig));
464 	p->p_procsig->ps_sigacts = tmpsigacts;
465 	bcopy(&csi->csi_sigacts, p->p_procsig->ps_sigacts, sizeof(struct sigacts));
466 	bcopy(&csi->csi_itimerval, &p->p_realtimer, sizeof(struct itimerval));
467 	SIG_CANTMASK(csi->csi_sigmask);
468 	bcopy(&csi->csi_sigmask, &p->p_sigmask, sizeof(sigset_t));
469 	p->p_sigparent = csi->csi_sigparent;
470  done:
471 	if (csi)
472 		free(csi, M_TEMP);
473 	TRACE_EXIT;
474 	return error;
475 }
476 
477 /*
478  * Returns a locked, refd vnode
479  */
480 static int
481 ckpt_fhtovp(fhandle_t *fh, struct vnode **vpp)
482 {
483 	struct mount *mp;
484 	int error;
485 
486 	TRACE_ENTER;
487 	mp = vfs_getvfs(&fh->fh_fsid);
488 
489 	if (!mp) {
490 		TRACE_ERR;
491 		PRINTF(("failed to get mount - ESTALE\n"));
492 	        TRACE_EXIT;
493 		return ESTALE;
494 	}
495 	error = VFS_FHTOVP(mp, &fh->fh_fid, vpp);
496 	if (error) {
497 		PRINTF(("failed with: %d\n", error));
498 		TRACE_ERR;
499 	        TRACE_EXIT;
500 		return error;
501 	}
502 	TRACE_EXIT;
503 	return 0;
504 }
505 
506 static int
507 mmap_vp(struct vn_hdr *vnh)
508 {
509 	struct vnode *vp;
510 	Elf_Phdr *phdr;
511 	struct file *fp;
512 	int error;
513 	TRACE_ENTER;
514 
515 	phdr = &vnh->vnh_phdr;
516 
517 	if ((error = ckpt_fhtovp(&vnh->vnh_fh, &vp)) != 0)
518 		return error;
519 	/*
520 	 * XXX O_RDONLY -> or O_RDWR if file is PROT_WRITE, MAP_SHARED
521 	 */
522 	if ((error = fp_vpopen(vp, O_RDONLY, &fp)) != 0) {
523 		vput(vp);
524 		return error;
525 	}
526 	error = mmap_phdr(fp, phdr);
527 	fp_close(fp);
528 	TRACE_EXIT;
529 	return error;
530 }
531 
532 
533 static int
534 elf_gettextvp(struct proc *p, struct file *fp)
535 {
536 	int i;
537 	int error;
538 	int vpcount;
539 	struct ckpt_vminfo vminfo;
540 	struct vn_hdr *vnh = NULL;
541 
542 	TRACE_ENTER;
543 	if ((error = read_check(fp, &vminfo, sizeof(vminfo))) != 0)
544 		goto done;
545 	if (vminfo.cvm_dsize < 0 ||
546 	    vminfo.cvm_dsize > p->p_rlimit[RLIMIT_DATA].rlim_cur ||
547 	    vminfo.cvm_tsize < 0 ||
548 	    (u_quad_t)vminfo.cvm_tsize > maxtsiz ||
549 	    vminfo.cvm_daddr >= (caddr_t)VM_MAXUSER_ADDRESS ||
550 	    vminfo.cvm_taddr >= (caddr_t)VM_MAXUSER_ADDRESS
551 	) {
552 	    error = ERANGE;
553 	    goto done;
554 	}
555 
556 	vmspace_exec(p, NULL);
557 	p->p_vmspace->vm_daddr = vminfo.cvm_daddr;
558 	p->p_vmspace->vm_dsize = vminfo.cvm_dsize;
559 	p->p_vmspace->vm_taddr = vminfo.cvm_taddr;
560 	p->p_vmspace->vm_tsize = vminfo.cvm_tsize;
561 	if ((error = read_check(fp, &vpcount, sizeof(int))) != 0)
562 		goto done;
563 	vnh = malloc(sizeof(struct vn_hdr) * vpcount, M_TEMP, M_WAITOK);
564 	if ((error = read_check(fp, vnh, sizeof(struct vn_hdr)*vpcount)) != 0)
565 		goto done;
566 	for (i = 0; i < vpcount; i++) {
567 		if ((error = mmap_vp(&vnh[i])) != 0)
568 			goto done;
569 	}
570 
571  done:
572 	if (vnh)
573 		free(vnh, M_TEMP);
574 	TRACE_EXIT;
575 	return error;
576 }
577 
578 
579 
580 /* place holder */
581 static int
582 elf_getfiles(struct proc *p, struct file *fp)
583 {
584 	int error;
585 	int i;
586 	int filecount;
587 	int fd;
588 	struct ckpt_filehdr filehdr;
589 	struct ckpt_fileinfo *cfi_base = NULL;
590 	struct vnode *vp;
591 	struct file *tempfp;
592 	struct file *ofp;
593 
594 	TRACE_ENTER;
595 	if ((error = read_check(fp, &filehdr, sizeof(filehdr))) != 0)
596 		goto done;
597 	filecount = filehdr.cfh_nfiles;
598 	cfi_base = malloc(filecount*sizeof(struct ckpt_fileinfo), M_TEMP, M_WAITOK);
599 	error = read_check(fp, cfi_base, filecount*sizeof(struct ckpt_fileinfo));
600 	if (error)
601 		goto done;
602 
603 	/*
604 	 * Close all file descriptors >= 3.  These descriptors are from the
605 	 * checkpt(1) program itself and should not be retained.
606 	 *
607 	 * XXX we need a flag so a checkpoint restore can opt to supply the
608 	 * descriptors, or the non-regular-file descripors.
609 	 */
610 	for (i = 3; i < p->p_fd->fd_nfiles; ++i)
611 		kern_close(i);
612 
613 	/*
614 	 * Scan files to load
615 	 */
616 	for (i = 0; i < filecount; i++) {
617 		struct ckpt_fileinfo *cfi= &cfi_base[i];
618 		/*
619 		 * Ignore placeholder entries where cfi_index is less then
620 		 * zero.  This will occur if the elf core dump code thinks
621 		 * it can save a vnode but winds up not being able to.
622 		 */
623 		if (cfi->cfi_index < 0)
624 			continue;
625 
626 		if ((error = ckpt_fhtovp(&cfi->cfi_fh, &vp)) != 0)
627 			break;
628 		if ((error = fp_vpopen(vp, OFLAGS(cfi->cfi_flags), &tempfp)) != 0) {
629 			vput(vp);
630 			break;
631 		}
632 		tempfp->f_offset = cfi->cfi_offset;
633 
634 		/*
635 		 * If overwriting a descriptor close the old descriptor.  This
636 		 * only occurs if the saved core saved descriptors that we
637 		 * have not already closed.
638 		 */
639 		if (cfi->cfi_index < p->p_fd->fd_nfiles &&
640 		    (ofp = p->p_fd->fd_files[cfi->cfi_index].fp) != NULL) {
641 			kern_close(cfi->cfi_index);
642 		}
643 
644 		/*
645 		 * Allocate the descriptor we want.
646 		 */
647 		if (fdalloc(p, cfi->cfi_index, &fd) != 0) {
648 			PRINTF(("can't currently restore fd: %d\n",
649 			       cfi->cfi_index));
650 			fp_close(fp);
651 			goto done;
652 		}
653 		KKASSERT(fd == cfi->cfi_index);
654 		p->p_fd->fd_files[cfi->cfi_index].fp = tempfp;
655 		cfi++;
656 		PRINTF(("restoring %d\n", cfi->cfi_index));
657 	}
658 
659  done:
660 	if (cfi_base)
661 		free(cfi_base, M_TEMP);
662 	TRACE_EXIT;
663 	return error;
664 }
665 
666 static int
667 ckpt_freeze_proc (struct proc *p, struct file *fp)
668 {
669 	rlim_t limit;
670 	int error;
671 
672         PRINTF(("calling generic_elf_coredump\n"));
673 	limit = p->p_rlimit[RLIMIT_CORE].rlim_cur;
674 	if (limit) {
675 		error = generic_elf_coredump(p, fp, limit);
676 	} else {
677 		error = ERANGE;
678 	}
679 	return error;
680 }
681 
682 int
683 sys_checkpoint(struct sys_checkpoint_args *uap)
684 {
685         int error = 0;
686 	struct proc *p = curthread->td_proc;
687 	struct file *fp;
688 
689 	/*
690 	 * Only certain groups (to reduce our security exposure).  -1
691 	 * allows any group.
692 	 */
693 	if (ckptgroup >= 0 && groupmember(ckptgroup, p->p_ucred) == 0)
694 		return (EPERM);
695 
696 	/*
697 	 * For now we can only checkpoint the current process
698 	 */
699 	if (uap->pid != -1 && uap->pid != p->p_pid)
700 		return (EINVAL);
701 
702 	switch (uap->type) {
703 	case CKPT_FREEZE:
704 		fp = NULL;
705 		if (uap->fd == -1 && uap->pid == (pid_t)-1)
706 			error = checkpoint_signal_handler(p);
707 		else if ((fp = holdfp(p->p_fd, uap->fd, FWRITE)) == NULL)
708 			error = EBADF;
709 		else
710 			error = ckpt_freeze_proc(p, fp);
711 		if (fp)
712 			fdrop(fp, curthread);
713 		break;
714 	case CKPT_THAW:
715 		if (uap->pid != -1)
716 			return EINVAL;
717 		if ((fp = holdfp(p->p_fd, uap->fd, FREAD)) == NULL)
718 			return EBADF;
719 		uap->sysmsg_result = uap->retval;
720 	        error = ckpt_thaw_proc(p, fp);
721 		fdrop(fp, curthread);
722 		break;
723 	default:
724 	        error = EOPNOTSUPP;
725 		break;
726 	}
727 	return error;
728 }
729 
730 int
731 checkpoint_signal_handler(struct proc *p)
732 {
733 	char *buf;
734 	struct file *fp;
735 	struct nlookupdata nd;
736 	int error;
737 
738 	chptinuse++;
739 
740 	/*
741 	 * Being able to checkpoint an suid or sgid program is not a good
742 	 * idea.
743 	 */
744 	if (sugid_coredump == 0 && (p->p_flag & P_SUGID)) {
745 		chptinuse--;
746 		return (EPERM);
747 	}
748 
749 	buf = ckpt_expand_name(p->p_comm, p->p_ucred->cr_uid, p->p_pid);
750 	if (buf == NULL) {
751 		chptinuse--;
752 		return (ENOMEM);
753 	}
754 
755 	log(LOG_INFO, "pid %d (%s), uid %d: checkpointing to %s\n",
756 		p->p_pid, p->p_comm,
757 		(p->p_ucred ? p->p_ucred->cr_uid : -1),
758 		buf);
759 
760 	PRINTF(("ckpt handler called, using '%s'\n", buf));
761 
762 	/*
763 	 * Use the same safety flags that the coredump code uses.  Remove
764 	 * any previous checkpoint file before writing out the new one in
765 	 * case we are re-checkpointing a program that had been checkpt
766 	 * restored.  Otherwise we will corrupt the program space (which is
767 	 * made up of mmap()ings of the previous checkpoint file) while we
768 	 * write out the new one.
769 	 */
770 	error = nlookup_init(&nd, buf, UIO_SYSSPACE, 0);
771 	if (error == 0)
772 		error = kern_unlink(&nd);
773 	nlookup_done(&nd);
774 	error = fp_open(buf, O_WRONLY|O_CREAT|O_TRUNC|O_NOFOLLOW, 0600, &fp);
775 	if (error == 0) {
776 		error = ckpt_freeze_proc(p, fp);
777 		fp_close(fp);
778 	} else {
779 		printf("checkpoint failed with open - error: %d\n", error);
780 	}
781 	free(buf, M_TEMP);
782 	chptinuse--;
783 	return (error);
784 }
785 
786 static char ckptfilename[MAXPATHLEN] = {"%N.ckpt"};
787 SYSCTL_STRING(_kern, OID_AUTO, ckptfile, CTLFLAG_RW, ckptfilename,
788 	      sizeof(ckptfilename), "process checkpoint name format string");
789 
790 /*
791  * expand_name(name, uid, pid)
792  * Expand the name described in corefilename, using name, uid, and pid.
793  * corefilename is a printf-like string, with three format specifiers:
794  *	%N	name of process ("name")
795  *	%P	process id (pid)
796  *	%U	user id (uid)
797  * For example, "%N.core" is the default; they can be disabled completely
798  * by using "/dev/null", or all core files can be stored in "/cores/%U/%N-%P".
799  * This is controlled by the sysctl variable kern.corefile (see above).
800  *
801  * -- taken from the coredump code
802  */
803 
804 static
805 char *
806 ckpt_expand_name(const char *name, uid_t uid, pid_t pid)
807 {
808 	char *temp;
809 	char *bp;
810 	char buf[11];		/* Buffer for pid/uid -- max 4B */
811 	int error;
812 	int i;
813 	int n;
814 	char *format = ckptfilename;
815 	size_t namelen;
816 
817 	temp = malloc(MAXPATHLEN + 1, M_TEMP, M_NOWAIT);
818 	if (temp == NULL)
819 		return NULL;
820 	namelen = strlen(name);
821 	n = 0;
822 	if (ckptfilename[0] != '/') {
823 		if ((bp = kern_getcwd(temp, MAXPATHLEN - 1, &error)) == NULL) {
824 			free(temp, M_TEMP);
825 			return NULL;
826 		}
827 		n = strlen(bp);
828 		bcopy(bp, temp, n + 1);	/* normalize location of the path */
829 		temp[n++] = '/';
830 		temp[n] = '\0';
831 	}
832 	for (i= 0; n < MAXPATHLEN && format[i]; i++) {
833 		int l;
834 		switch (format[i]) {
835 		case '%':	/* Format character */
836 			i++;
837 			switch (format[i]) {
838 			case '%':
839 				temp[n++] = '%';
840 				break;
841 			case 'N':	/* process name */
842 				if ((n + namelen) > MAXPATHLEN) {
843 					log(LOG_ERR, "pid %d (%s), uid (%u):  Path `%s%s' is too long\n",
844 					    pid, name, uid, temp, name);
845 					free(temp, M_TEMP);
846 					return NULL;
847 				}
848 				memcpy(temp+n, name, namelen);
849 				n += namelen;
850 				break;
851 			case 'P':	/* process id */
852 				l = sprintf(buf, "%u", pid);
853 				if ((n + l) > MAXPATHLEN) {
854 					log(LOG_ERR, "pid %d (%s), uid (%u):  Path `%s%s' is too long\n",
855 					    pid, name, uid, temp, name);
856 					free(temp, M_TEMP);
857 					return NULL;
858 				}
859 				memcpy(temp+n, buf, l);
860 				n += l;
861 				break;
862 			case 'U':	/* user id */
863 				l = sprintf(buf, "%u", uid);
864 				if ((n + l) > MAXPATHLEN) {
865 					log(LOG_ERR, "pid %d (%s), uid (%u):  Path `%s%s' is too long\n",
866 					    pid, name, uid, temp, name);
867 					free(temp, M_TEMP);
868 					return NULL;
869 				}
870 				memcpy(temp+n, buf, l);
871 				n += l;
872 				break;
873 			default:
874 			  	log(LOG_ERR, "Unknown format character %c in `%s'\n", format[i], format);
875 			}
876 			break;
877 		default:
878 			temp[n++] = format[i];
879 		}
880 	}
881 	temp[n] = '\0';
882 	return temp;
883 }
884 
885