xref: /titanic_51/usr/src/lib/libctf/common/ctf_lib.c (revision a3477ee4728af4a4c3c6869e248aa735d52cbefb)
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
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 *
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
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 *
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
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
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 *
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
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 *
192 ctf_fdopen(int fd, int *errp)
193 {
194 	ctf_sect_t ctfsect, symsect, strsect;
195 	ctf_file_t *fp = NULL;
196 
197 	struct stat64 st;
198 	ssize_t nbytes;
199 
200 	union {
201 		ctf_preamble_t ctf;
202 		Elf32_Ehdr e32;
203 		GElf_Ehdr e64;
204 	} hdr;
205 
206 	bzero(&ctfsect, sizeof (ctf_sect_t));
207 	bzero(&symsect, sizeof (ctf_sect_t));
208 	bzero(&strsect, sizeof (ctf_sect_t));
209 	bzero(&hdr.ctf, sizeof (hdr));
210 
211 	if (fstat64(fd, &st) == -1)
212 		return (ctf_set_open_errno(errp, errno));
213 
214 	if ((nbytes = pread64(fd, &hdr.ctf, sizeof (hdr), 0)) <= 0)
215 		return (ctf_set_open_errno(errp, nbytes < 0? errno : ECTF_FMT));
216 
217 	/*
218 	 * If we have read enough bytes to form a CTF header and the magic
219 	 * string matches, attempt to interpret the file as raw CTF.
220 	 */
221 	if (nbytes >= sizeof (ctf_preamble_t) &&
222 	    hdr.ctf.ctp_magic == CTF_MAGIC) {
223 		if (hdr.ctf.ctp_version > CTF_VERSION)
224 			return (ctf_set_open_errno(errp, ECTF_CTFVERS));
225 
226 		ctfsect.cts_data = mmap64(NULL, st.st_size, PROT_READ,
227 		    MAP_PRIVATE, fd, 0);
228 
229 		if (ctfsect.cts_data == MAP_FAILED)
230 			return (ctf_set_open_errno(errp, errno));
231 
232 		ctfsect.cts_name = _CTF_SECTION;
233 		ctfsect.cts_type = SHT_PROGBITS;
234 		ctfsect.cts_flags = SHF_ALLOC;
235 		ctfsect.cts_size = (size_t)st.st_size;
236 		ctfsect.cts_entsize = 1;
237 		ctfsect.cts_offset = 0;
238 
239 		if ((fp = ctf_bufopen(&ctfsect, NULL, NULL, errp)) == NULL)
240 			ctf_sect_munmap(&ctfsect);
241 
242 		return (fp);
243 	}
244 
245 	/*
246 	 * If we have read enough bytes to form an ELF header and the magic
247 	 * string matches, attempt to interpret the file as an ELF file.  We
248 	 * do our own largefile ELF processing, and convert everything to
249 	 * GElf structures so that clients can operate on any data model.
250 	 */
251 	if (nbytes >= sizeof (Elf32_Ehdr) &&
252 	    bcmp(&hdr.e32.e_ident[EI_MAG0], ELFMAG, SELFMAG) == 0) {
253 #ifdef	_BIG_ENDIAN
254 		uchar_t order = ELFDATA2MSB;
255 #else
256 		uchar_t order = ELFDATA2LSB;
257 #endif
258 		GElf_Half i, n;
259 		GElf_Shdr *sp;
260 
261 		void *strs_map;
262 		size_t strs_mapsz;
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 		if (hdr.e64.e_shstrndx >= hdr.e64.e_shnum)
279 			return (ctf_set_open_errno(errp, ECTF_CORRUPT));
280 
281 		n = hdr.e64.e_shnum;
282 		nbytes = sizeof (GElf_Shdr) * n;
283 
284 		if ((sp = malloc(nbytes)) == NULL)
285 			return (ctf_set_open_errno(errp, errno));
286 
287 		/*
288 		 * Read in and convert to GElf the array of Shdr structures
289 		 * from e_shoff so we can locate sections of interest.
290 		 */
291 		if (hdr.e32.e_ident[EI_CLASS] == ELFCLASS32) {
292 			Elf32_Shdr *sp32;
293 
294 			nbytes = sizeof (Elf32_Shdr) * n;
295 
296 			if ((sp32 = malloc(nbytes)) == NULL || pread64(fd,
297 			    sp32, nbytes, hdr.e64.e_shoff) != nbytes) {
298 				free(sp);
299 				return (ctf_set_open_errno(errp, errno));
300 			}
301 
302 			for (i = 0; i < n; i++)
303 				shdr_to_gelf(&sp32[i], &sp[i]);
304 
305 			free(sp32);
306 
307 		} else if (pread64(fd, sp, nbytes, hdr.e64.e_shoff) != nbytes) {
308 			free(sp);
309 			return (ctf_set_open_errno(errp, errno));
310 		}
311 
312 		/*
313 		 * Now mmap the section header strings section so that we can
314 		 * perform string comparison on the section names.
315 		 */
316 		strs_mapsz = sp[hdr.e64.e_shstrndx].sh_size +
317 		    (sp[hdr.e64.e_shstrndx].sh_offset & ~_PAGEMASK);
318 
319 		strs_map = mmap64(NULL, strs_mapsz, PROT_READ, MAP_PRIVATE,
320 		    fd, sp[hdr.e64.e_shstrndx].sh_offset & _PAGEMASK);
321 
322 		strs = (const char *)strs_map +
323 		    (sp[hdr.e64.e_shstrndx].sh_offset & ~_PAGEMASK);
324 
325 		if (strs_map == MAP_FAILED) {
326 			free(sp);
327 			return (ctf_set_open_errno(errp, ECTF_MMAP));
328 		}
329 
330 		/*
331 		 * Iterate over the section header array looking for the CTF
332 		 * section and symbol table.  The strtab is linked to symtab.
333 		 */
334 		for (i = 0; i < n; i++) {
335 			const GElf_Shdr *shp = &sp[i];
336 			const GElf_Shdr *lhp = &sp[shp->sh_link];
337 
338 			if (shp->sh_link >= hdr.e64.e_shnum)
339 				continue; /* corrupt sh_link field */
340 
341 			if (shp->sh_name >= sp[hdr.e64.e_shstrndx].sh_size ||
342 			    lhp->sh_name >= sp[hdr.e64.e_shstrndx].sh_size)
343 				continue; /* corrupt sh_name field */
344 
345 			if (shp->sh_type == SHT_PROGBITS &&
346 			    strcmp(strs + shp->sh_name, _CTF_SECTION) == 0) {
347 				ctfsect.cts_name = strs + shp->sh_name;
348 				ctfsect.cts_type = shp->sh_type;
349 				ctfsect.cts_flags = shp->sh_flags;
350 				ctfsect.cts_size = shp->sh_size;
351 				ctfsect.cts_entsize = shp->sh_entsize;
352 				ctfsect.cts_offset = (off64_t)shp->sh_offset;
353 
354 			} else if (shp->sh_type == SHT_SYMTAB) {
355 				symsect.cts_name = strs + shp->sh_name;
356 				symsect.cts_type = shp->sh_type;
357 				symsect.cts_flags = shp->sh_flags;
358 				symsect.cts_size = shp->sh_size;
359 				symsect.cts_entsize = shp->sh_entsize;
360 				symsect.cts_offset = (off64_t)shp->sh_offset;
361 
362 				strsect.cts_name = strs + lhp->sh_name;
363 				strsect.cts_type = lhp->sh_type;
364 				strsect.cts_flags = lhp->sh_flags;
365 				strsect.cts_size = lhp->sh_size;
366 				strsect.cts_entsize = lhp->sh_entsize;
367 				strsect.cts_offset = (off64_t)lhp->sh_offset;
368 			}
369 		}
370 
371 		free(sp); /* free section header array */
372 
373 		if (ctfsect.cts_type == SHT_NULL) {
374 			(void) munmap(strs_map, strs_mapsz);
375 			return (ctf_set_open_errno(errp, ECTF_NOCTFDATA));
376 		}
377 
378 		/*
379 		 * Now mmap the CTF data, symtab, and strtab sections and
380 		 * call ctf_bufopen() to do the rest of the work.
381 		 */
382 		if (ctf_sect_mmap(&ctfsect, fd) == MAP_FAILED) {
383 			(void) munmap(strs_map, strs_mapsz);
384 			return (ctf_set_open_errno(errp, ECTF_MMAP));
385 		}
386 
387 		if (symsect.cts_type != SHT_NULL &&
388 		    strsect.cts_type != SHT_NULL) {
389 			if (ctf_sect_mmap(&symsect, fd) == MAP_FAILED ||
390 			    ctf_sect_mmap(&strsect, fd) == MAP_FAILED) {
391 				(void) ctf_set_open_errno(errp, ECTF_MMAP);
392 				goto bad; /* unmap all and abort */
393 			}
394 			fp = ctf_bufopen(&ctfsect, &symsect, &strsect, errp);
395 		} else
396 			fp = ctf_bufopen(&ctfsect, NULL, NULL, errp);
397 bad:
398 		if (fp == NULL) {
399 			ctf_sect_munmap(&ctfsect);
400 			ctf_sect_munmap(&symsect);
401 			ctf_sect_munmap(&strsect);
402 		} else
403 			fp->ctf_flags |= LCTF_MMAP;
404 
405 		(void) munmap(strs_map, strs_mapsz);
406 		return (fp);
407 	}
408 
409 	return (ctf_set_open_errno(errp, ECTF_FMT));
410 }
411 
412 /*
413  * Open the specified file and return a pointer to a CTF container.  The file
414  * can be either an ELF file or raw CTF file.  This is just a convenient
415  * wrapper around ctf_fdopen() for callers.
416  */
417 ctf_file_t *
418 ctf_open(const char *filename, int *errp)
419 {
420 	ctf_file_t *fp;
421 	int fd;
422 
423 	if ((fd = open64(filename, O_RDONLY)) == -1) {
424 		if (errp != NULL)
425 			*errp = errno;
426 		return (NULL);
427 	}
428 
429 	fp = ctf_fdopen(fd, errp);
430 	(void) close(fd);
431 	return (fp);
432 }
433 
434 /*
435  * Write the uncompressed CTF data stream to the specified file descriptor.
436  * This is useful for saving the results of dynamic CTF containers.
437  */
438 int
439 ctf_write(ctf_file_t *fp, int fd)
440 {
441 	const uchar_t *buf = fp->ctf_base;
442 	ssize_t resid = fp->ctf_size;
443 	ssize_t len;
444 
445 	while (resid != 0) {
446 		if ((len = write(fd, buf, resid)) <= 0)
447 			return (ctf_set_errno(fp, errno));
448 		resid -= len;
449 		buf += len;
450 	}
451 
452 	return (0);
453 }
454 
455 /*
456  * Set the CTF library client version to the specified version.  If version is
457  * zero, we just return the default library version number.
458  */
459 int
460 ctf_version(int version)
461 {
462 	if (version < 0) {
463 		errno = EINVAL;
464 		return (-1);
465 	}
466 
467 	if (version > 0) {
468 		if (version > CTF_VERSION) {
469 			errno = ENOTSUP;
470 			return (-1);
471 		}
472 		ctf_dprintf("ctf_version: client using version %d\n", version);
473 		_libctf_version = version;
474 	}
475 
476 	return (_libctf_version);
477 }
478