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GCC Code Coverage Report

Directory:	./		Exec	Total	Coverage
File:	usr.bin/ctfdump/elf.c	Lines:	0	130	0.0 %
Date:	2017-11-13	Branches:	0	128	0.0 %


/*	$OpenBSD: elf.c,v 1.7 2017/11/06 14:59:27 mpi Exp $ */

/*
 * Copyright (c) 2016 Martin Pieuchot <mpi@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <sys/types.h>

#include <machine/reloc.h>

#include <assert.h>
#include <elf.h>
#include <err.h>
#include <string.h>

static int	elf_reloc_size(unsigned long);
static void	elf_reloc_apply(const char *, size_t, const char *, size_t,
		    ssize_t, char *, size_t);

int
iself(const char *p, size_t filesize)
{
	Elf_Ehdr		*eh = (Elf_Ehdr *)p;

	if (filesize < (off_t)sizeof(Elf_Ehdr)) {
		warnx("file too small to be ELF");
		return 0;
	}

	if (eh->e_ehsize < sizeof(Elf_Ehdr) || !IS_ELF(*eh))
		return 0;

	if (eh->e_ident[EI_CLASS] != ELFCLASS) {
		warnx("unexpected word size %u", eh->e_ident[EI_CLASS]);
		return 0;
	}
	if (eh->e_ident[EI_VERSION] != ELF_TARG_VER) {
		warnx("unexpected version %u", eh->e_ident[EI_VERSION]);
		return 0;
	}
	if (eh->e_ident[EI_DATA] >= ELFDATANUM) {
		warnx("unexpected data format %u", eh->e_ident[EI_DATA]);
		return 0;
	}
	if (eh->e_shoff > filesize) {
		warnx("bogus section table offset 0x%llx", (off_t)eh->e_shoff);
		return 0;
	}
	if (eh->e_shentsize < sizeof(Elf_Shdr)) {
		warnx("bogus section header size %u", eh->e_shentsize);
		return 0;
	}
	if (eh->e_shnum > (filesize - eh->e_shoff) / eh->e_shentsize) {
		warnx("bogus section header count %u", eh->e_shnum);
		return 0;
	}
	if (eh->e_shstrndx >= eh->e_shnum) {
		warnx("bogus string table index %u", eh->e_shstrndx);
		return 0;
	}

	return 1;
}

int
elf_getshstab(const char *p, size_t filesize, const char **shstab,
    size_t *shstabsize)
{
	Elf_Ehdr		*eh = (Elf_Ehdr *)p;
	Elf_Shdr		*sh;

	sh = (Elf_Shdr *)(p + eh->e_shoff + eh->e_shstrndx * eh->e_shentsize);
	if (sh->sh_type != SHT_STRTAB) {
		warnx("unexpected string table type");
		return -1;
	}
	if (sh->sh_offset > filesize) {
		warnx("bogus string table offset");
		return -1;
	}
	if (sh->sh_size > filesize - sh->sh_offset) {
		warnx("bogus string table size");
		return -1;
	}
	if (shstab != NULL)
		*shstab = p + sh->sh_offset;
	if (shstabsize != NULL)
		*shstabsize = sh->sh_size;

	return 0;
}

ssize_t
elf_getsymtab(const char *p, size_t filesize, const char *shstab,
    size_t shstabsz, const Elf_Sym **symtab, size_t *nsymb, const char **strtab,
    size_t *strtabsz)
{
	Elf_Ehdr	*eh = (Elf_Ehdr *)p;
	Elf_Shdr	*sh, *symsh;
	size_t		 snlen;
	ssize_t		 i;

	snlen = strlen(ELF_SYMTAB);
	symsh = NULL;

	for (i = 0; i < eh->e_shnum; i++) {
		sh = (Elf_Shdr *)(p + eh->e_shoff + i * eh->e_shentsize);

		if (sh->sh_type != SHT_SYMTAB)
			continue;

		if ((sh->sh_link >= eh->e_shnum) || (sh->sh_name >= shstabsz))
			continue;

		if ((sh->sh_offset + sh->sh_size) > filesize)
			continue;

		if (sh->sh_entsize == 0)
			continue;

		if (strncmp(shstab + sh->sh_name, ELF_SYMTAB, snlen) == 0) {
			if (symtab != NULL)
				*symtab = (Elf_Sym *)(p + sh->sh_offset);
			if (nsymb != NULL)
				*nsymb = (sh->sh_size / sh->sh_entsize);
			symsh = sh;

			break;
		}
	}

	if (symsh == NULL || (symsh->sh_link >= eh->e_shnum))
		return -1;

	sh = (Elf_Shdr *)(p + eh->e_shoff + symsh->sh_link * eh->e_shentsize);

	if ((sh->sh_offset + sh->sh_size) > filesize)
		return -1;

	if (strtab != NULL)
		*strtab = p + sh->sh_offset;
	if (strtabsz != NULL)
		*strtabsz = sh->sh_size;

	return i;
}

ssize_t
elf_getsection(char *p, size_t filesize, const char *sname, const char *shstab,
    size_t shstabsz, const char **psdata, size_t *pssz)
{
	Elf_Ehdr	*eh = (Elf_Ehdr *)p;
	Elf_Shdr	*sh;
	char		*sdata = NULL;
	size_t		 snlen, ssz = 0;
	ssize_t		 sidx, i;

	snlen = strlen(sname);
	if (snlen == 0)
		return -1;

	/* Find the given section. */
	for (i = 0; i < eh->e_shnum; i++) {
		if ((eh->e_shoff + i * eh->e_shentsize) > filesize)
			continue;

		sh = (Elf_Shdr *)(p + eh->e_shoff + i * eh->e_shentsize);

		if ((sh->sh_link >= eh->e_shnum) || (sh->sh_name >= shstabsz))
			continue;

		if ((sh->sh_offset + sh->sh_size) > filesize)
			continue;

		if (strncmp(shstab + sh->sh_name, sname, snlen) == 0) {
			sidx = i;
			sdata = p + sh->sh_offset;
			ssz = sh->sh_size;
			elf_reloc_apply(p, filesize, shstab, shstabsz, sidx,
			    sdata, ssz);
			break;
		}
	}

	if (sdata == NULL)
		return -1;

	if (psdata != NULL)
		*psdata = sdata;
	if (pssz != NULL)
		*pssz = ssz;

	return sidx;
}

static int
elf_reloc_size(unsigned long type)
{
	switch (type) {
#ifdef R_X86_64_64
	case R_X86_64_64:
		return sizeof(uint64_t);
#endif
#ifdef R_X86_64_32
	case R_X86_64_32:
		return sizeof(uint32_t);
#endif
#ifdef RELOC_32
	case RELOC_32:
		return sizeof(uint32_t);
#endif
	default:
		break;
	}

	return -1;
}

#define ELF_WRITE_RELOC(buf, val, rsize)				\
do {									\
	if (rsize == 4) {						\
		uint32_t v32 = val;					\
		memcpy(buf, &v32, sizeof(v32));				\
	} else {							\
		uint64_t v64 = val;					\
		memcpy(buf, &v64, sizeof(v64));				\
	}								\
} while (0)

static void
elf_reloc_apply(const char *p, size_t filesize, const char *shstab,
    size_t shstabsz, ssize_t sidx, char *sdata, size_t ssz)
{
	Elf_Ehdr	*eh = (Elf_Ehdr *)p;
	Elf_Shdr	*sh;
	Elf_Rel		*rel = NULL;
	Elf_RelA	*rela = NULL;
	const Elf_Sym	*symtab, *sym;
	ssize_t		 symtabidx;
	size_t		 nsymb, rsym, rtyp, roff;
	size_t		 i, j;
	uint64_t	 value;
	int		 rsize;

	/* Find symbol table location and number of symbols. */
	symtabidx = elf_getsymtab(p, filesize, shstab, shstabsz, &symtab,
	    &nsymb, NULL, NULL);
	if (symtabidx == -1) {
		warnx("symbol table not found");
		return;
	}

	/* Apply possible relocation. */
	for (i = 0; i < eh->e_shnum; i++) {
		if ((eh->e_shoff + i * eh->e_shentsize) > filesize)
			continue;

		sh = (Elf_Shdr *)(p + eh->e_shoff + i * eh->e_shentsize);

		if (sh->sh_size == 0)
			continue;

		if ((sh->sh_info != sidx) || (sh->sh_link != symtabidx))
			continue;

		if ((sh->sh_offset + sh->sh_size) > filesize)
			continue;

		switch (sh->sh_type) {
		case SHT_RELA:
			rela = (Elf_RelA *)(p + sh->sh_offset);
			for (j = 0; j < (sh->sh_size / sizeof(Elf_RelA)); j++) {
				rsym = ELF_R_SYM(rela[j].r_info);
				rtyp = ELF_R_TYPE(rela[j].r_info);
				roff = rela[j].r_offset;
				if (rsym >= nsymb)
					continue;
				if (roff >= filesize)
					continue;
				sym = &symtab[rsym];
				value = sym->st_value + rela[j].r_addend;

				rsize = elf_reloc_size(rtyp);
				if (rsize == -1 || roff + rsize >= ssz)
					continue;

				ELF_WRITE_RELOC(sdata + roff, value, rsize);
			}
			break;
		case SHT_REL:
			rel = (Elf_Rel *)(p + sh->sh_offset);
			for (j = 0; j < (sh->sh_size / sizeof(Elf_Rel)); j++) {
				rsym = ELF_R_SYM(rel[j].r_info);
				rtyp = ELF_R_TYPE(rel[j].r_info);
				roff = rel[j].r_offset;
				if (rsym >= nsymb)
					continue;
				if (roff >= filesize)
					continue;
				sym = &symtab[rsym];
				value = sym->st_value;

				rsize = elf_reloc_size(rtyp);
				if (rsize == -1 || roff + rsize >= ssz)
					continue;

				ELF_WRITE_RELOC(sdata + roff, value, rsize);
			}
			break;
		default:
			continue;
		}
	}
}


Generated by: GCOVR (Version 3.3)

Line	Branch	Exec	Source
1			/* $OpenBSD: elf.c,v 1.7 2017/11/06 14:59:27 mpi Exp $ */
2
3			/*
4			* Copyright (c) 2016 Martin Pieuchot <mpi@openbsd.org>
5			*
6			* Permission to use, copy, modify, and distribute this software for any
7			* purpose with or without fee is hereby granted, provided that the above
8			* copyright notice and this permission notice appear in all copies.
9			*
10			* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
11			* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
12			* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
13			* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
14			* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
15			* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
16			* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
17			*/
18
19			#include <sys/types.h>
20
21			#include <machine/reloc.h>
22
23			#include <assert.h>
24			#include <elf.h>
25			#include <err.h>
26			#include <string.h>
27
28			static int elf_reloc_size(unsigned long);
29			static void elf_reloc_apply(const char , size_t, const char , size_t,
30			ssize_t, char *, size_t);
31
32			int
33			iself(const char *p, size_t filesize)
34			{
35			Elf_Ehdr eh = (Elf_Ehdr )p;
36
37			if (filesize < (off_t)sizeof(Elf_Ehdr)) {
38			warnx("file too small to be ELF");
39			return 0;
40			}
41
42			if (eh->e_ehsize < sizeof(Elf_Ehdr) \|\| !IS_ELF(*eh))
43			return 0;
44
45			if (eh->e_ident[EI_CLASS] != ELFCLASS) {
46			warnx("unexpected word size %u", eh->e_ident[EI_CLASS]);
47			return 0;
48			}
49			if (eh->e_ident[EI_VERSION] != ELF_TARG_VER) {
50			warnx("unexpected version %u", eh->e_ident[EI_VERSION]);
51			return 0;
52			}
53			if (eh->e_ident[EI_DATA] >= ELFDATANUM) {
54			warnx("unexpected data format %u", eh->e_ident[EI_DATA]);
55			return 0;
56			}
57			if (eh->e_shoff > filesize) {
58			warnx("bogus section table offset 0x%llx", (off_t)eh->e_shoff);
59			return 0;
60			}
61			if (eh->e_shentsize < sizeof(Elf_Shdr)) {
62			warnx("bogus section header size %u", eh->e_shentsize);
63			return 0;
64			}
65			if (eh->e_shnum > (filesize - eh->e_shoff) / eh->e_shentsize) {
66			warnx("bogus section header count %u", eh->e_shnum);
67			return 0;
68			}
69			if (eh->e_shstrndx >= eh->e_shnum) {
70			warnx("bogus string table index %u", eh->e_shstrndx);
71			return 0;
72			}
73
74			return 1;
75			}
76
77			int
78			elf_getshstab(const char p, size_t filesize, const char *shstab,
79			size_t *shstabsize)
80			{
81			Elf_Ehdr eh = (Elf_Ehdr )p;
82			Elf_Shdr *sh;
83
84			sh = (Elf_Shdr )(p + eh->e_shoff + eh->e_shstrndx eh->e_shentsize);
85			if (sh->sh_type != SHT_STRTAB) {
86			warnx("unexpected string table type");
87			return -1;
88			}
89			if (sh->sh_offset > filesize) {
90			warnx("bogus string table offset");
91			return -1;
92			}
93			if (sh->sh_size > filesize - sh->sh_offset) {
94			warnx("bogus string table size");
95			return -1;
96			}
97			if (shstab != NULL)
98			*shstab = p + sh->sh_offset;
99			if (shstabsize != NULL)
100			*shstabsize = sh->sh_size;
101
102			return 0;
103			}
104
105			ssize_t
106			elf_getsymtab(const char p, size_t filesize, const char shstab,
107			size_t shstabsz, const Elf_Sym *symtab, size_t nsymb, const char **strtab,
108			size_t *strtabsz)
109			{
110			Elf_Ehdr eh = (Elf_Ehdr )p;
111			Elf_Shdr sh, symsh;
112			size_t snlen;
113			ssize_t i;
114
115			snlen = strlen(ELF_SYMTAB);
116			symsh = NULL;
117
118			for (i = 0; i < eh->e_shnum; i++) {
119			sh = (Elf_Shdr )(p + eh->e_shoff + i eh->e_shentsize);
120
121			if (sh->sh_type != SHT_SYMTAB)
122			continue;
123
124			if ((sh->sh_link >= eh->e_shnum) \|\| (sh->sh_name >= shstabsz))
125			continue;
126
127			if ((sh->sh_offset + sh->sh_size) > filesize)
128			continue;
129
130			if (sh->sh_entsize == 0)
131			continue;
132
133			if (strncmp(shstab + sh->sh_name, ELF_SYMTAB, snlen) == 0) {
134			if (symtab != NULL)
135			symtab = (Elf_Sym )(p + sh->sh_offset);
136			if (nsymb != NULL)
137			*nsymb = (sh->sh_size / sh->sh_entsize);
138			symsh = sh;
139
140			break;
141			}
142			}
143
144			if (symsh == NULL \|\| (symsh->sh_link >= eh->e_shnum))
145			return -1;
146
147			sh = (Elf_Shdr )(p + eh->e_shoff + symsh->sh_link eh->e_shentsize);
148
149			if ((sh->sh_offset + sh->sh_size) > filesize)
150			return -1;
151
152			if (strtab != NULL)
153			*strtab = p + sh->sh_offset;
154			if (strtabsz != NULL)
155			*strtabsz = sh->sh_size;
156
157			return i;
158			}
159
160			ssize_t
161			elf_getsection(char p, size_t filesize, const char sname, const char *shstab,
162			size_t shstabsz, const char *psdata, size_t pssz)
163			{
164			Elf_Ehdr eh = (Elf_Ehdr )p;
165			Elf_Shdr *sh;
166			char *sdata = NULL;
167			size_t snlen, ssz = 0;
168			ssize_t sidx, i;
169
170			snlen = strlen(sname);
171			if (snlen == 0)
172			return -1;
173
174			/* Find the given section. */
175			for (i = 0; i < eh->e_shnum; i++) {
176			if ((eh->e_shoff + i * eh->e_shentsize) > filesize)
177			continue;
178
179			sh = (Elf_Shdr )(p + eh->e_shoff + i eh->e_shentsize);
180
181			if ((sh->sh_link >= eh->e_shnum) \|\| (sh->sh_name >= shstabsz))
182			continue;
183
184			if ((sh->sh_offset + sh->sh_size) > filesize)
185			continue;
186
187			if (strncmp(shstab + sh->sh_name, sname, snlen) == 0) {
188			sidx = i;
189			sdata = p + sh->sh_offset;
190			ssz = sh->sh_size;
191			elf_reloc_apply(p, filesize, shstab, shstabsz, sidx,
192			sdata, ssz);
193			break;
194			}
195			}
196
197			if (sdata == NULL)
198			return -1;
199
200			if (psdata != NULL)
201			*psdata = sdata;
202			if (pssz != NULL)
203			*pssz = ssz;
204
205			return sidx;
206			}
207
208			static int
209			elf_reloc_size(unsigned long type)
210			{
211			switch (type) {
212			#ifdef R_X86_64_64
213			case R_X86_64_64:
214			return sizeof(uint64_t);
215			#endif
216			#ifdef R_X86_64_32
217			case R_X86_64_32:
218			return sizeof(uint32_t);
219			#endif
220			#ifdef RELOC_32
221			case RELOC_32:
222			return sizeof(uint32_t);
223			#endif
224			default:
225			break;
226			}
227
228			return -1;
229			}
230
231			#define ELF_WRITE_RELOC(buf, val, rsize) \
232			do { \
233			if (rsize == 4) { \
234			uint32_t v32 = val; \
235			memcpy(buf, &v32, sizeof(v32)); \
236			} else { \
237			uint64_t v64 = val; \
238			memcpy(buf, &v64, sizeof(v64)); \
239			} \
240			} while (0)
241
242			static void
243			elf_reloc_apply(const char p, size_t filesize, const char shstab,
244			size_t shstabsz, ssize_t sidx, char *sdata, size_t ssz)
245			{
246			Elf_Ehdr eh = (Elf_Ehdr )p;
247			Elf_Shdr *sh;
248			Elf_Rel *rel = NULL;
249			Elf_RelA *rela = NULL;
250			const Elf_Sym symtab, sym;
251			ssize_t symtabidx;
252			size_t nsymb, rsym, rtyp, roff;
253			size_t i, j;
254			uint64_t value;
255			int rsize;
256
257			/* Find symbol table location and number of symbols. */
258			symtabidx = elf_getsymtab(p, filesize, shstab, shstabsz, &symtab,
259			&nsymb, NULL, NULL);
260			if (symtabidx == -1) {
261			warnx("symbol table not found");
262			return;
263			}
264
265			/* Apply possible relocation. */
266			for (i = 0; i < eh->e_shnum; i++) {
267			if ((eh->e_shoff + i * eh->e_shentsize) > filesize)
268			continue;
269
270			sh = (Elf_Shdr )(p + eh->e_shoff + i eh->e_shentsize);
271
272			if (sh->sh_size == 0)
273			continue;
274
275			if ((sh->sh_info != sidx) \|\| (sh->sh_link != symtabidx))
276			continue;
277
278			if ((sh->sh_offset + sh->sh_size) > filesize)
279			continue;
280
281			switch (sh->sh_type) {
282			case SHT_RELA:
283			rela = (Elf_RelA *)(p + sh->sh_offset);
284			for (j = 0; j < (sh->sh_size / sizeof(Elf_RelA)); j++) {
285			rsym = ELF_R_SYM(rela[j].r_info);
286			rtyp = ELF_R_TYPE(rela[j].r_info);
287			roff = rela[j].r_offset;
288			if (rsym >= nsymb)
289			continue;
290			if (roff >= filesize)
291			continue;
292			sym = &symtab[rsym];
293			value = sym->st_value + rela[j].r_addend;
294
295			rsize = elf_reloc_size(rtyp);
296			if (rsize == -1 \|\| roff + rsize >= ssz)
297			continue;
298
299			ELF_WRITE_RELOC(sdata + roff, value, rsize);
300			}
301			break;
302			case SHT_REL:
303			rel = (Elf_Rel *)(p + sh->sh_offset);
304			for (j = 0; j < (sh->sh_size / sizeof(Elf_Rel)); j++) {
305			rsym = ELF_R_SYM(rel[j].r_info);
306			rtyp = ELF_R_TYPE(rel[j].r_info);
307			roff = rel[j].r_offset;
308			if (rsym >= nsymb)
309			continue;
310			if (roff >= filesize)
311			continue;
312			sym = &symtab[rsym];
313			value = sym->st_value;
314
315			rsize = elf_reloc_size(rtyp);
316			if (rsize == -1 \|\| roff + rsize >= ssz)
317			continue;
318
319			ELF_WRITE_RELOC(sdata + roff, value, rsize);
320			}
321			break;
322			default:
323			continue;
324			}
325			}
326			}