[ctfdump/.git] / elf.c

/*
 * 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/param.h>
#include <sys/exec_elf.h>

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

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

	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_getshstrtab(const char *p, size_t filesize, const char **shstrtab,
    size_t *shstrtabsize)
{
	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 (shstrtab != NULL)
		*shstrtab = p + sh->sh_offset;
	if (shstrtabsize != NULL)
		*shstrtabsize = sh->sh_size;

	return 0;
}

int
elf_getsymtab(const char *p, const char *shstrtab, size_t shstrtabsize,
    const Elf_Sym **symtab, size_t *nsymb)
{
	Elf_Ehdr	*eh = (Elf_Ehdr *)p;
	Elf_Shdr	*sh;
	size_t		 i;

	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 >= shstrtabsize))
			continue;

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

			return 0;
		}
	}

	return 1;
}

int
elf_getsection(const char *p, const char *sname, const char *shstrtab,
    size_t shstrtabsize, const char **sdata, size_t *ssize)
{
	Elf_Ehdr	*eh = (Elf_Ehdr *)p;
	Elf_Shdr	*sh;
	size_t		 i;

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

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

		if (strncmp(shstrtab + sh->sh_name, sname,
		    strlen(sname)) == 0) {
			if (sdata != NULL)
				*sdata = p + sh->sh_offset;
			if (ssize != NULL)
				*ssize = sh->sh_size;

			return 0;
		}
	}

	return 1;
}
Commit	Line	Data
c36bfc0c MP	1	/*
	2	* Copyright (c) 2016 Martin Pieuchot <mpi@openbsd.org>
	3	*
	4	* Permission to use, copy, modify, and distribute this software for any
	5	* purpose with or without fee is hereby granted, provided that the above
	6	* copyright notice and this permission notice appear in all copies.
	7	*
	8	* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
	9	* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
	10	* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
	11	* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
	12	* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
	13	* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
	14	* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
	15	*/
	16
	17	#include <sys/param.h>
	18	#include <sys/exec_elf.h>
	19
	20	#include <err.h>
	21	#include <string.h>
	22
	23	int
	24	iself(const char *p, size_t filesize)
	25	{
	26	Elf_Ehdr eh = (Elf_Ehdr )p;
	27
	28	if (eh->e_ehsize < sizeof(Elf_Ehdr) \|\| !IS_ELF(*eh))
	29	return 0;
	30
	31	if (eh->e_ident[EI_CLASS] != ELFCLASS) {
	32	warnx("unexpected word size %u", eh->e_ident[EI_CLASS]);
	33	return 0;
	34	}
	35	if (eh->e_ident[EI_VERSION] != ELF_TARG_VER) {
	36	warnx("unexpected version %u", eh->e_ident[EI_VERSION]);
	37	return 0;
	38	}
	39	if (eh->e_ident[EI_DATA] >= ELFDATANUM) {
	40	warnx("unexpected data format %u", eh->e_ident[EI_DATA]);
	41	return 0;
	42	}
	43	if (eh->e_shoff > filesize) {
	44	warnx("bogus section table offset 0x%llx", (off_t)eh->e_shoff);
	45	return 0;
	46	}
	47	if (eh->e_shentsize < sizeof(Elf_Shdr)) {
	48	warnx("bogus section header size %u", eh->e_shentsize);
	49	return 0;
	50	}
	51	if (eh->e_shnum > (filesize - eh->e_shoff) / eh->e_shentsize) {
	52	warnx("bogus section header count %u", eh->e_shnum);
	53	return 0;
	54	}
	55	if (eh->e_shstrndx >= eh->e_shnum) {
	56	warnx("bogus string table index %u", eh->e_shstrndx);
	57	return 0;
	58	}
	59
	60	return 1;
	61	}
	62
	63	int
	64	elf_getshstrtab(const char p, size_t filesize, const char *shstrtab,
65	size_t *shstrtabsize)
66	{
67	Elf_Ehdr eh = (Elf_Ehdr )p;
68	Elf_Shdr *sh;
69
70	sh = (Elf_Shdr )(p + eh->e_shoff + eh->e_shstrndx eh->e_shentsize);
71	if (sh->sh_type != SHT_STRTAB) {
72	warnx("unexpected string table type");
73	return 1;
74	}
75	if (sh->sh_offset > filesize) {
76	warnx("bogus string table offset");
77	return 1;
78	}
79	if (sh->sh_size > filesize - sh->sh_offset) {
80	warnx("bogus string table size");
81	return 1;
82	}
83	if (shstrtab != NULL)
84	*shstrtab = p + sh->sh_offset;
85	if (shstrtabsize != NULL)
86	*shstrtabsize = sh->sh_size;
87
88	return 0;
89	}
90
91	int
92	elf_getsymtab(const char p, const char shstrtab, size_t shstrtabsize,
93	const Elf_Sym *symtab, size_t nsymb)
94	{
95	Elf_Ehdr eh = (Elf_Ehdr )p;
96	Elf_Shdr *sh;
97	size_t i;
98
99	for (i = 0; i < eh->e_shnum; i++) {
100	sh = (Elf_Shdr )(p + eh->e_shoff + i eh->e_shentsize);
101
102	if (sh->sh_type != SHT_SYMTAB)
103	continue;
104
105	if ((sh->sh_link >= eh->e_shnum) \|\|
106	(sh->sh_name >= shstrtabsize))
107	continue;
108
109	if (strncmp(shstrtab + sh->sh_name, ELF_SYMTAB,
110	strlen(ELF_SYMTAB)) == 0) {
111	if (symtab != NULL)
112	symtab = (Elf_Sym )(p + sh->sh_offset);
113	if (nsymb != NULL)
114	*nsymb = (sh->sh_size / sh->sh_entsize);
115
116	return 0;
117	}
118	}
119
120	return 1;
121	}
122
123	int
2ef38d60 MP	124	elf_getsection(const char p, const char sname, const char *shstrtab,
2ef38d60 MP	125	size_t shstrtabsize, const char *sdata, size_t ssize)
c36bfc0c MP	126	{
	127	Elf_Ehdr eh = (Elf_Ehdr )p;
	128	Elf_Shdr *sh;
	129	size_t i;
	130
	131	for (i = 0; i < eh->e_shnum; i++) {
	132	sh = (Elf_Shdr )(p + eh->e_shoff + i eh->e_shentsize);
	133
c36bfc0c MP	134	if ((sh->sh_link >= eh->e_shnum) \|\|
	135	(sh->sh_name >= shstrtabsize))
	136	continue;
	137
2ef38d60 MP	138	if (strncmp(shstrtab + sh->sh_name, sname,
	139	strlen(sname)) == 0) {
	140	if (sdata != NULL)
	141	*sdata = p + sh->sh_offset;
	142	if (ssize != NULL)
	143	*ssize = sh->sh_size;
c36bfc0c MP	144
	145	return 0;
	146	}
	147	}
	148
	149	return 1;
	150	}