Head

GCC Code Coverage Report

Directory:	./		Exec	Total	Coverage
File:	usr.bin/ctfconv/elf.c	Lines:	68	126	54.0 %
Date:	2017-11-07	Branches:	46	118	39.0 %


/*	$OpenBSD: elf.c,v 1.6 2017/09/30 10:15:59 jsg 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 <sys/exec_elf.h>

#include <machine/reloc.h>

#include <assert.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)
{
	Elf_Ehdr	*eh = (Elf_Ehdr *)p;
	Elf_Shdr	*sh;
	size_t		 snlen;
	ssize_t		 i;

	snlen = strlen(ELF_SYMTAB);

	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);

			return i;
		}
	}

	return -1;
}

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);
	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 1.6 2017/09/30 10:15:59 jsg 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			#include <sys/exec_elf.h>
21
22			#include <machine/reloc.h>
23
24			#include <assert.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		4	Elf_Ehdr eh = (Elf_Ehdr )p;
36
37	✗✓	2	if (filesize < (off_t)sizeof(Elf_Ehdr)) {
38			warnx("file too small to be ELF");
39			return 0;
40			}
41
42	✓✗✓✗ ✓✗✓✗ ✗✓	10	if (eh->e_ehsize < sizeof(Elf_Ehdr) \|\| !IS_ELF(*eh))
43			return 0;
44
45	✗✓	2	if (eh->e_ident[EI_CLASS] != ELFCLASS) {
46			warnx("unexpected word size %u", eh->e_ident[EI_CLASS]);
47			return 0;
48			}
49	✗✓	2	if (eh->e_ident[EI_VERSION] != ELF_TARG_VER) {
50			warnx("unexpected version %u", eh->e_ident[EI_VERSION]);
51			return 0;
52			}
53	✗✓	2	if (eh->e_ident[EI_DATA] >= ELFDATANUM) {
54			warnx("unexpected data format %u", eh->e_ident[EI_DATA]);
55			return 0;
56			}
57	✗✓	2	if (eh->e_shoff > filesize) {
58			warnx("bogus section table offset 0x%llx", (off_t)eh->e_shoff);
59			return 0;
60			}
61	✗✓	2	if (eh->e_shentsize < sizeof(Elf_Shdr)) {
62			warnx("bogus section header size %u", eh->e_shentsize);
63			return 0;
64			}
65	✗✓	2	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	✗✓	2	if (eh->e_shstrndx >= eh->e_shnum) {
70			warnx("bogus string table index %u", eh->e_shstrndx);
71			return 0;
72			}
73
74		2	return 1;
75		2	}
76
77			int
78			elf_getshstab(const char p, size_t filesize, const char *shstab,
79			size_t *shstabsize)
80			{
81		4	Elf_Ehdr eh = (Elf_Ehdr )p;
82			Elf_Shdr *sh;
83
84		2	sh = (Elf_Shdr )(p + eh->e_shoff + eh->e_shstrndx eh->e_shentsize);
85	✗✓	2	if (sh->sh_type != SHT_STRTAB) {
86			warnx("unexpected string table type");
87			return -1;
88			}
89	✗✓	2	if (sh->sh_offset > filesize) {
90			warnx("bogus string table offset");
91			return -1;
92			}
93	✗✓	2	if (sh->sh_size > filesize - sh->sh_offset) {
94			warnx("bogus string table size");
95			return -1;
96			}
97	✓✗	2	if (shstab != NULL)
98		2	*shstab = p + sh->sh_offset;
99	✓✗	2	if (shstabsize != NULL)
100		2	*shstabsize = sh->sh_size;
101
102		2	return 0;
103		2	}
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)
108			{
109		20	Elf_Ehdr eh = (Elf_Ehdr )p;
110			Elf_Shdr *sh;
111			size_t snlen;
112			ssize_t i;
113
114			snlen = strlen(ELF_SYMTAB);
115
116	✓✗	620	for (i = 0; i < eh->e_shnum; i++) {
117		310	sh = (Elf_Shdr )(p + eh->e_shoff + i eh->e_shentsize);
118
119	✓✓	310	if (sh->sh_type != SHT_SYMTAB)
120			continue;
121
122	✓✗✓✗	20	if ((sh->sh_link >= eh->e_shnum) \|\| (sh->sh_name >= shstabsz))
123			continue;
124
125	✓✗	10	if ((sh->sh_offset + sh->sh_size) > filesize)
126			continue;
127
128	✓✗	10	if (sh->sh_entsize == 0)
129			continue;
130
131	✓✗	10	if (strncmp(shstab + sh->sh_name, ELF_SYMTAB, snlen) == 0) {
132	✓✗	10	if (symtab != NULL)
133		10	symtab = (Elf_Sym )(p + sh->sh_offset);
134	✓✗	10	if (nsymb != NULL)
135		10	*nsymb = (sh->sh_size / sh->sh_entsize);
136
137		10	return i;
138			}
139			}
140
141			return -1;
142		10	}
143
144			ssize_t
145			elf_getsection(char p, size_t filesize, const char sname, const char *shstab,
146			size_t shstabsz, const char *psdata, size_t pssz)
147			{
148		16	Elf_Ehdr eh = (Elf_Ehdr )p;
149			Elf_Shdr *sh;
150			char *sdata = NULL;
151			size_t snlen, ssz = 0;
152			ssize_t sidx, i;
153
154		8	snlen = strlen(sname);
155	✗✓	8	if (snlen == 0)
156			return -1;
157
158			/* Find the given section. */
159	✓✗	420	for (i = 0; i < eh->e_shnum; i++) {
160	✓✗	210	if ((eh->e_shoff + i * eh->e_shentsize) > filesize)
161			continue;
162
163		210	sh = (Elf_Shdr )(p + eh->e_shoff + i eh->e_shentsize);
164
165	✓✗✓✗	420	if ((sh->sh_link >= eh->e_shnum) \|\| (sh->sh_name >= shstabsz))
166			continue;
167
168	✓✗	210	if ((sh->sh_offset + sh->sh_size) > filesize)
169			continue;
170
171	✓✓	210	if (strncmp(shstab + sh->sh_name, sname, snlen) == 0) {
172			sidx = i;
173		8	sdata = p + sh->sh_offset;
174		8	ssz = sh->sh_size;
175		8	elf_reloc_apply(p, filesize, shstab, shstabsz, sidx,
176			sdata, ssz);
177		8	break;
178			}
179			}
180
181	✗✓	8	if (sdata == NULL)
182			return -1;
183
184	✓✗	8	if (psdata != NULL)
185		8	*psdata = sdata;
186	✓✗	8	if (pssz != NULL)
187		8	*pssz = ssz;
188
189		8	return sidx;
190		8	}
191
192			static int
193			elf_reloc_size(unsigned long type)
194			{
195			switch (type) {
196			#ifdef R_X86_64_64
197			case R_X86_64_64:
198			return sizeof(uint64_t);
199			#endif
200			#ifdef R_X86_64_32
201			case R_X86_64_32:
202			return sizeof(uint32_t);
203			#endif
204			#ifdef RELOC_32
205			case RELOC_32:
206			return sizeof(uint32_t);
207			#endif
208			default:
209			break;
210			}
211
212			return -1;
213			}
214
215			#define ELF_WRITE_RELOC(buf, val, rsize) \
216			do { \
217			if (rsize == 4) { \
218			uint32_t v32 = val; \
219			memcpy(buf, &v32, sizeof(v32)); \
220			} else { \
221			uint64_t v64 = val; \
222			memcpy(buf, &v64, sizeof(v64)); \
223			} \
224			} while (0)
225
226			static void
227			elf_reloc_apply(const char p, size_t filesize, const char shstab,
228			size_t shstabsz, ssize_t sidx, char *sdata, size_t ssz)
229			{
230		16	Elf_Ehdr eh = (Elf_Ehdr )p;
231			Elf_Shdr *sh;
232			Elf_Rel *rel = NULL;
233			Elf_RelA *rela = NULL;
234		8	const Elf_Sym symtab, sym;
235			ssize_t symtabidx;
236		8	size_t nsymb, rsym, rtyp, roff;
237			size_t i, j;
238			uint64_t value;
239			int rsize;
240
241			/* Find symbol table location and number of symbols. */
242		8	symtabidx = elf_getsymtab(p, filesize, shstab, shstabsz, &symtab,
243			&nsymb);
244	✗✓	8	if (symtabidx == -1) {
245			warnx("symbol table not found");
246			return;
247			}
248
249			/* Apply possible relocation. */
250	✓✓	528	for (i = 0; i < eh->e_shnum; i++) {
251	✓✗	256	if ((eh->e_shoff + i * eh->e_shentsize) > filesize)
252			continue;
253
254		256	sh = (Elf_Shdr )(p + eh->e_shoff + i eh->e_shentsize);
255
256	✓✓	256	if (sh->sh_size == 0)
257			continue;
258
259	✗✓✗✗	248	if ((sh->sh_info != sidx) \|\| (sh->sh_link != symtabidx))
260			continue;
261
262			if ((sh->sh_offset + sh->sh_size) > filesize)
263			continue;
264
265			switch (sh->sh_type) {
266			case SHT_RELA:
267			rela = (Elf_RelA *)(p + sh->sh_offset);
268			for (j = 0; j < (sh->sh_size / sizeof(Elf_RelA)); j++) {
269			rsym = ELF_R_SYM(rela[j].r_info);
270			rtyp = ELF_R_TYPE(rela[j].r_info);
271			roff = rela[j].r_offset;
272			if (rsym >= nsymb)
273			continue;
274			if (roff >= filesize)
275			continue;
276			sym = &symtab[rsym];
277			value = sym->st_value + rela[j].r_addend;
278
279			rsize = elf_reloc_size(rtyp);
280			if (rsize == -1 \|\| roff + rsize >= ssz)
281			continue;
282
283			ELF_WRITE_RELOC(sdata + roff, value, rsize);
284			}
285			break;
286			case SHT_REL:
287			rel = (Elf_Rel *)(p + sh->sh_offset);
288			for (j = 0; j < (sh->sh_size / sizeof(Elf_Rel)); j++) {
289			rsym = ELF_R_SYM(rel[j].r_info);
290			rtyp = ELF_R_TYPE(rel[j].r_info);
291			roff = rel[j].r_offset;
292			if (rsym >= nsymb)
293			continue;
294			if (roff >= filesize)
295			continue;
296			sym = &symtab[rsym];
297			value = sym->st_value;
298
299			rsize = elf_reloc_size(rtyp);
300			if (rsize == -1 \|\| roff + rsize >= ssz)
301			continue;
302
303			ELF_WRITE_RELOC(sdata + roff, value, rsize);
304			}
305			break;
306			default:
307			continue;
308			}
309			}
310		16	}