xref: /titanic_41/usr/src/lib/libctf/common/ctf_lib.c (revision 0b42f15ac52b077791d4ba079e8c163c592c3fda)
1 /*
2  * CDDL HEADER START
3  *
4  * The contents of this file are subject to the terms of the
5  * Common Development and Distribution License, Version 1.0 only
6  * (the "License").  You may not use this file except in compliance
7  * with the License.
8  *
9  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10  * or http://www.opensolaris.org/os/licensing.
11  * See the License for the specific language governing permissions
12  * and limitations under the License.
13  *
14  * When distributing Covered Code, include this CDDL HEADER in each
15  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16  * If applicable, add the following below this CDDL HEADER, with the
17  * fields enclosed by brackets "[]" replaced with your own identifying
18  * information: Portions Copyright [yyyy] [name of copyright owner]
19  *
20  * CDDL HEADER END
21  */
22 /*
23  * Copyright 2003 Sun Microsystems, Inc.  All rights reserved.
24  * Use is subject to license terms.
25  */
26 
27 #include <sys/types.h>
28 #include <sys/stat.h>
29 #include <sys/mman.h>
30 #include <ctf_impl.h>
31 #include <unistd.h>
32 #include <fcntl.h>
33 #include <errno.h>
34 #include <dlfcn.h>
35 #include <gelf.h>
36 
37 #ifdef _LP64
38 static const char *_libctf_zlib = "/usr/lib/64/libz.so.1";
39 #else
40 static const char *_libctf_zlib = "/usr/lib/libz.so.1";
41 #endif
42 
43 static struct {
44 	int (*z_uncompress)(uchar_t *, ulong_t *, const uchar_t *, ulong_t);
45 	const char *(*z_error)(int);
46 	void *z_dlp;
47 } zlib;
48 
49 static size_t _PAGESIZE;
50 static size_t _PAGEMASK;
51 
52 #pragma init(_libctf_init)
53 void
_libctf_init(void)54 _libctf_init(void)
55 {
56 	const char *p = getenv("LIBCTF_DECOMPRESSOR");
57 
58 	if (p != NULL)
59 		_libctf_zlib = p; /* use alternate decompression library */
60 
61 	_libctf_debug = getenv("LIBCTF_DEBUG") != NULL;
62 
63 	_PAGESIZE = getpagesize();
64 	_PAGEMASK = ~(_PAGESIZE - 1);
65 }
66 
67 /*
68  * Attempt to dlopen the decompression library and locate the symbols of
69  * interest that we will need to call.  This information in cached so
70  * that multiple calls to ctf_bufopen() do not need to reopen the library.
71  */
72 void *
ctf_zopen(int * errp)73 ctf_zopen(int *errp)
74 {
75 	ctf_dprintf("decompressing CTF data using %s\n", _libctf_zlib);
76 
77 	if (zlib.z_dlp != NULL)
78 		return (zlib.z_dlp); /* library is already loaded */
79 
80 	if (access(_libctf_zlib, R_OK) == -1)
81 		return (ctf_set_open_errno(errp, ECTF_ZMISSING));
82 
83 	if ((zlib.z_dlp = dlopen(_libctf_zlib, RTLD_LAZY | RTLD_LOCAL)) == NULL)
84 		return (ctf_set_open_errno(errp, ECTF_ZINIT));
85 
86 	zlib.z_uncompress = (int (*)()) dlsym(zlib.z_dlp, "uncompress");
87 	zlib.z_error = (const char *(*)()) dlsym(zlib.z_dlp, "zError");
88 
89 	if (zlib.z_uncompress == NULL || zlib.z_error == NULL) {
90 		(void) dlclose(zlib.z_dlp);
91 		bzero(&zlib, sizeof (zlib));
92 		return (ctf_set_open_errno(errp, ECTF_ZINIT));
93 	}
94 
95 	return (zlib.z_dlp);
96 }
97 
98 /*
99  * The ctf_bufopen() routine calls these subroutines, defined by <sys/zmod.h>,
100  * which we then patch through to the functions in the decompression library.
101  */
102 int
z_uncompress(void * dst,size_t * dstlen,const void * src,size_t srclen)103 z_uncompress(void *dst, size_t *dstlen, const void *src, size_t srclen)
104 {
105 	return (zlib.z_uncompress(dst, (ulong_t *)dstlen, src, srclen));
106 }
107 
108 const char *
z_strerror(int err)109 z_strerror(int err)
110 {
111 	return (zlib.z_error(err));
112 }
113 
114 /*
115  * Convert a 32-bit ELF file header into GElf.
116  */
117 static void
ehdr_to_gelf(const Elf32_Ehdr * src,GElf_Ehdr * dst)118 ehdr_to_gelf(const Elf32_Ehdr *src, GElf_Ehdr *dst)
119 {
120 	bcopy(src->e_ident, dst->e_ident, EI_NIDENT);
121 	dst->e_type = src->e_type;
122 	dst->e_machine = src->e_machine;
123 	dst->e_version = src->e_version;
124 	dst->e_entry = (Elf64_Addr)src->e_entry;
125 	dst->e_phoff = (Elf64_Off)src->e_phoff;
126 	dst->e_shoff = (Elf64_Off)src->e_shoff;
127 	dst->e_flags = src->e_flags;
128 	dst->e_ehsize = src->e_ehsize;
129 	dst->e_phentsize = src->e_phentsize;
130 	dst->e_phnum = src->e_phnum;
131 	dst->e_shentsize = src->e_shentsize;
132 	dst->e_shnum = src->e_shnum;
133 	dst->e_shstrndx = src->e_shstrndx;
134 }
135 
136 /*
137  * Convert a 32-bit ELF section header into GElf.
138  */
139 static void
shdr_to_gelf(const Elf32_Shdr * src,GElf_Shdr * dst)140 shdr_to_gelf(const Elf32_Shdr *src, GElf_Shdr *dst)
141 {
142 	dst->sh_name = src->sh_name;
143 	dst->sh_type = src->sh_type;
144 	dst->sh_flags = src->sh_flags;
145 	dst->sh_addr = src->sh_addr;
146 	dst->sh_offset = src->sh_offset;
147 	dst->sh_size = src->sh_size;
148 	dst->sh_link = src->sh_link;
149 	dst->sh_info = src->sh_info;
150 	dst->sh_addralign = src->sh_addralign;
151 	dst->sh_entsize = src->sh_entsize;
152 }
153 
154 /*
155  * In order to mmap a section from the ELF file, we must round down sh_offset
156  * to the previous page boundary, and mmap the surrounding page.  We store
157  * the pointer to the start of the actual section data back into sp->cts_data.
158  */
159 const void *
ctf_sect_mmap(ctf_sect_t * sp,int fd)160 ctf_sect_mmap(ctf_sect_t *sp, int fd)
161 {
162 	size_t pageoff = sp->cts_offset & ~_PAGEMASK;
163 
164 	caddr_t base = mmap64(NULL, sp->cts_size + pageoff, PROT_READ,
165 	    MAP_PRIVATE, fd, sp->cts_offset & _PAGEMASK);
166 
167 	if (base != MAP_FAILED)
168 		sp->cts_data = base + pageoff;
169 
170 	return (base);
171 }
172 
173 /*
174  * Since sp->cts_data has the adjusted offset, we have to again round down
175  * to get the actual mmap address and round up to get the size.
176  */
177 void
ctf_sect_munmap(const ctf_sect_t * sp)178 ctf_sect_munmap(const ctf_sect_t *sp)
179 {
180 	uintptr_t addr = (uintptr_t)sp->cts_data;
181 	uintptr_t pageoff = addr & ~_PAGEMASK;
182 
183 	(void) munmap((void *)(addr - pageoff), sp->cts_size + pageoff);
184 }
185 
186 /*
187  * Open the specified file descriptor and return a pointer to a CTF container.
188  * The file can be either an ELF file or raw CTF file.  The caller is
189  * responsible for closing the file descriptor when it is no longer needed.
190  */
191 ctf_file_t *
ctf_fdopen(int fd,int * errp)192 ctf_fdopen(int fd, int *errp)
193 {
194 	ctf_sect_t ctfsect, symsect, strsect;
195 	ctf_file_t *fp = NULL;
196 	size_t shstrndx, shnum;
197 
198 	struct stat64 st;
199 	ssize_t nbytes;
200 
201 	union {
202 		ctf_preamble_t ctf;
203 		Elf32_Ehdr e32;
204 		GElf_Ehdr e64;
205 	} hdr;
206 
207 	bzero(&ctfsect, sizeof (ctf_sect_t));
208 	bzero(&symsect, sizeof (ctf_sect_t));
209 	bzero(&strsect, sizeof (ctf_sect_t));
210 	bzero(&hdr.ctf, sizeof (hdr));
211 
212 	if (fstat64(fd, &st) == -1)
213 		return (ctf_set_open_errno(errp, errno));
214 
215 	if ((nbytes = pread64(fd, &hdr.ctf, sizeof (hdr), 0)) <= 0)
216 		return (ctf_set_open_errno(errp, nbytes < 0? errno : ECTF_FMT));
217 
218 	/*
219 	 * If we have read enough bytes to form a CTF header and the magic
220 	 * string matches, attempt to interpret the file as raw CTF.
221 	 */
222 	if (nbytes >= sizeof (ctf_preamble_t) &&
223 	    hdr.ctf.ctp_magic == CTF_MAGIC) {
224 		if (hdr.ctf.ctp_version > CTF_VERSION)
225 			return (ctf_set_open_errno(errp, ECTF_CTFVERS));
226 
227 		ctfsect.cts_data = mmap64(NULL, st.st_size, PROT_READ,
228 		    MAP_PRIVATE, fd, 0);
229 
230 		if (ctfsect.cts_data == MAP_FAILED)
231 			return (ctf_set_open_errno(errp, errno));
232 
233 		ctfsect.cts_name = _CTF_SECTION;
234 		ctfsect.cts_type = SHT_PROGBITS;
235 		ctfsect.cts_flags = SHF_ALLOC;
236 		ctfsect.cts_size = (size_t)st.st_size;
237 		ctfsect.cts_entsize = 1;
238 		ctfsect.cts_offset = 0;
239 
240 		if ((fp = ctf_bufopen(&ctfsect, NULL, NULL, errp)) == NULL)
241 			ctf_sect_munmap(&ctfsect);
242 
243 		return (fp);
244 	}
245 
246 	/*
247 	 * If we have read enough bytes to form an ELF header and the magic
248 	 * string matches, attempt to interpret the file as an ELF file.  We
249 	 * do our own largefile ELF processing, and convert everything to
250 	 * GElf structures so that clients can operate on any data model.
251 	 */
252 	if (nbytes >= sizeof (Elf32_Ehdr) &&
253 	    bcmp(&hdr.e32.e_ident[EI_MAG0], ELFMAG, SELFMAG) == 0) {
254 #ifdef	_BIG_ENDIAN
255 		uchar_t order = ELFDATA2MSB;
256 #else
257 		uchar_t order = ELFDATA2LSB;
258 #endif
259 		GElf_Shdr *sp;
260 
261 		void *strs_map;
262 		size_t strs_mapsz, i;
263 		const char *strs;
264 
265 		if (hdr.e32.e_ident[EI_DATA] != order)
266 			return (ctf_set_open_errno(errp, ECTF_ENDIAN));
267 		if (hdr.e32.e_version != EV_CURRENT)
268 			return (ctf_set_open_errno(errp, ECTF_ELFVERS));
269 
270 		if (hdr.e32.e_ident[EI_CLASS] == ELFCLASS64) {
271 			if (nbytes < sizeof (GElf_Ehdr))
272 				return (ctf_set_open_errno(errp, ECTF_FMT));
273 		} else {
274 			Elf32_Ehdr e32 = hdr.e32;
275 			ehdr_to_gelf(&e32, &hdr.e64);
276 		}
277 
278 		shnum = hdr.e64.e_shnum;
279 		shstrndx = hdr.e64.e_shstrndx;
280 
281 		/* Extended ELF sections */
282 		if ((shstrndx == SHN_XINDEX) || (shnum == 0)) {
283 			if (hdr.e32.e_ident[EI_CLASS] == ELFCLASS32) {
284 				Elf32_Shdr x32;
285 
286 				if (pread64(fd, &x32, sizeof (x32),
287 				    hdr.e64.e_shoff) != sizeof (x32))
288 					return (ctf_set_open_errno(errp,
289 					    errno));
290 
291 				shnum = x32.sh_size;
292 				shstrndx = x32.sh_link;
293 			} else {
294 				Elf64_Shdr x64;
295 
296 				if (pread64(fd, &x64, sizeof (x64),
297 				    hdr.e64.e_shoff) != sizeof (x64))
298 					return (ctf_set_open_errno(errp,
299 					    errno));
300 
301 				shnum = x64.sh_size;
302 				shstrndx = x64.sh_link;
303 			}
304 		}
305 
306 		if (shstrndx >= shnum)
307 			return (ctf_set_open_errno(errp, ECTF_CORRUPT));
308 
309 		nbytes = sizeof (GElf_Shdr) * shnum;
310 
311 		if ((sp = malloc(nbytes)) == NULL)
312 			return (ctf_set_open_errno(errp, errno));
313 
314 		/*
315 		 * Read in and convert to GElf the array of Shdr structures
316 		 * from e_shoff so we can locate sections of interest.
317 		 */
318 		if (hdr.e32.e_ident[EI_CLASS] == ELFCLASS32) {
319 			Elf32_Shdr *sp32;
320 
321 			nbytes = sizeof (Elf32_Shdr) * shnum;
322 
323 			if ((sp32 = malloc(nbytes)) == NULL || pread64(fd,
324 			    sp32, nbytes, hdr.e64.e_shoff) != nbytes) {
325 				free(sp);
326 				return (ctf_set_open_errno(errp, errno));
327 			}
328 
329 			for (i = 0; i < shnum; i++)
330 				shdr_to_gelf(&sp32[i], &sp[i]);
331 
332 			free(sp32);
333 
334 		} else if (pread64(fd, sp, nbytes, hdr.e64.e_shoff) != nbytes) {
335 			free(sp);
336 			return (ctf_set_open_errno(errp, errno));
337 		}
338 
339 		/*
340 		 * Now mmap the section header strings section so that we can
341 		 * perform string comparison on the section names.
342 		 */
343 		strs_mapsz = sp[shstrndx].sh_size +
344 		    (sp[shstrndx].sh_offset & ~_PAGEMASK);
345 
346 		strs_map = mmap64(NULL, strs_mapsz, PROT_READ, MAP_PRIVATE,
347 		    fd, sp[shstrndx].sh_offset & _PAGEMASK);
348 
349 		strs = (const char *)strs_map +
350 		    (sp[shstrndx].sh_offset & ~_PAGEMASK);
351 
352 		if (strs_map == MAP_FAILED) {
353 			free(sp);
354 			return (ctf_set_open_errno(errp, ECTF_MMAP));
355 		}
356 
357 		/*
358 		 * Iterate over the section header array looking for the CTF
359 		 * section and symbol table.  The strtab is linked to symtab.
360 		 */
361 		for (i = 0; i < shnum; i++) {
362 			const GElf_Shdr *shp = &sp[i];
363 			const GElf_Shdr *lhp = &sp[shp->sh_link];
364 
365 			if (shp->sh_link >= shnum)
366 				continue; /* corrupt sh_link field */
367 
368 			if (shp->sh_name >= sp[shstrndx].sh_size ||
369 			    lhp->sh_name >= sp[shstrndx].sh_size)
370 				continue; /* corrupt sh_name field */
371 
372 			if (shp->sh_type == SHT_PROGBITS &&
373 			    strcmp(strs + shp->sh_name, _CTF_SECTION) == 0) {
374 				ctfsect.cts_name = strs + shp->sh_name;
375 				ctfsect.cts_type = shp->sh_type;
376 				ctfsect.cts_flags = shp->sh_flags;
377 				ctfsect.cts_size = shp->sh_size;
378 				ctfsect.cts_entsize = shp->sh_entsize;
379 				ctfsect.cts_offset = (off64_t)shp->sh_offset;
380 
381 			} else if (shp->sh_type == SHT_SYMTAB) {
382 				symsect.cts_name = strs + shp->sh_name;
383 				symsect.cts_type = shp->sh_type;
384 				symsect.cts_flags = shp->sh_flags;
385 				symsect.cts_size = shp->sh_size;
386 				symsect.cts_entsize = shp->sh_entsize;
387 				symsect.cts_offset = (off64_t)shp->sh_offset;
388 
389 				strsect.cts_name = strs + lhp->sh_name;
390 				strsect.cts_type = lhp->sh_type;
391 				strsect.cts_flags = lhp->sh_flags;
392 				strsect.cts_size = lhp->sh_size;
393 				strsect.cts_entsize = lhp->sh_entsize;
394 				strsect.cts_offset = (off64_t)lhp->sh_offset;
395 			}
396 		}
397 
398 		free(sp); /* free section header array */
399 
400 		if (ctfsect.cts_type == SHT_NULL) {
401 			(void) munmap(strs_map, strs_mapsz);
402 			return (ctf_set_open_errno(errp, ECTF_NOCTFDATA));
403 		}
404 
405 		/*
406 		 * Now mmap the CTF data, symtab, and strtab sections and
407 		 * call ctf_bufopen() to do the rest of the work.
408 		 */
409 		if (ctf_sect_mmap(&ctfsect, fd) == MAP_FAILED) {
410 			(void) munmap(strs_map, strs_mapsz);
411 			return (ctf_set_open_errno(errp, ECTF_MMAP));
412 		}
413 
414 		if (symsect.cts_type != SHT_NULL &&
415 		    strsect.cts_type != SHT_NULL) {
416 			if (ctf_sect_mmap(&symsect, fd) == MAP_FAILED ||
417 			    ctf_sect_mmap(&strsect, fd) == MAP_FAILED) {
418 				(void) ctf_set_open_errno(errp, ECTF_MMAP);
419 				goto bad; /* unmap all and abort */
420 			}
421 			fp = ctf_bufopen(&ctfsect, &symsect, &strsect, errp);
422 		} else
423 			fp = ctf_bufopen(&ctfsect, NULL, NULL, errp);
424 bad:
425 		if (fp == NULL) {
426 			ctf_sect_munmap(&ctfsect);
427 			ctf_sect_munmap(&symsect);
428 			ctf_sect_munmap(&strsect);
429 		} else
430 			fp->ctf_flags |= LCTF_MMAP;
431 
432 		(void) munmap(strs_map, strs_mapsz);
433 		return (fp);
434 	}
435 
436 	return (ctf_set_open_errno(errp, ECTF_FMT));
437 }
438 
439 /*
440  * Open the specified file and return a pointer to a CTF container.  The file
441  * can be either an ELF file or raw CTF file.  This is just a convenient
442  * wrapper around ctf_fdopen() for callers.
443  */
444 ctf_file_t *
ctf_open(const char * filename,int * errp)445 ctf_open(const char *filename, int *errp)
446 {
447 	ctf_file_t *fp;
448 	int fd;
449 
450 	if ((fd = open64(filename, O_RDONLY)) == -1) {
451 		if (errp != NULL)
452 			*errp = errno;
453 		return (NULL);
454 	}
455 
456 	fp = ctf_fdopen(fd, errp);
457 	(void) close(fd);
458 	return (fp);
459 }
460 
461 /*
462  * Write the uncompressed CTF data stream to the specified file descriptor.
463  * This is useful for saving the results of dynamic CTF containers.
464  */
465 int
ctf_write(ctf_file_t * fp,int fd)466 ctf_write(ctf_file_t *fp, int fd)
467 {
468 	const uchar_t *buf = fp->ctf_base;
469 	ssize_t resid = fp->ctf_size;
470 	ssize_t len;
471 
472 	while (resid != 0) {
473 		if ((len = write(fd, buf, resid)) <= 0)
474 			return (ctf_set_errno(fp, errno));
475 		resid -= len;
476 		buf += len;
477 	}
478 
479 	return (0);
480 }
481 
482 /*
483  * Set the CTF library client version to the specified version.  If version is
484  * zero, we just return the default library version number.
485  */
486 int
ctf_version(int version)487 ctf_version(int version)
488 {
489 	if (version < 0) {
490 		errno = EINVAL;
491 		return (-1);
492 	}
493 
494 	if (version > 0) {
495 		if (version > CTF_VERSION) {
496 			errno = ENOTSUP;
497 			return (-1);
498 		}
499 		ctf_dprintf("ctf_version: client using version %d\n", version);
500 		_libctf_version = version;
501 	}
502 
503 	return (_libctf_version);
504 }
505