HardenedBSD/lib/libproc/proc_sym.c
Mark Johnston 5aa9b11b61 Take the mapping's segment offset into account when resolving symbols.
Reported by:	Jenkins, via asomers
MFC after:	2 weeks
2018-07-21 22:15:48 +00:00

720 lines
17 KiB
C

/*-
* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
*
* Copyright (c) 2016-2017 Mark Johnston <markj@FreeBSD.org>
* Copyright (c) 2010 The FreeBSD Foundation
* Copyright (c) 2008 John Birrell (jb@freebsd.org)
* All rights reserved.
*
* Portions of this software were developed by Rui Paulo under sponsorship
* from the FreeBSD Foundation.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/types.h>
#ifndef NO_CTF
#include <sys/ctf.h>
#include <sys/ctf_api.h>
#endif
#include <sys/user.h>
#include <assert.h>
#include <err.h>
#include <fcntl.h>
#include <libgen.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#ifndef NO_CTF
#include <libctf.h>
#endif
#include <libutil.h>
#include "crc32.h"
#include "_libproc.h"
#define PATH_DEBUG_DIR "/usr/lib/debug"
#ifdef NO_CTF
typedef struct ctf_file ctf_file_t;
#endif
#ifndef NO_CXA_DEMANGLE
extern char *__cxa_demangle(const char *, char *, size_t *, int *);
#endif /* NO_CXA_DEMANGLE */
static int
crc32_file(int fd, uint32_t *crc)
{
uint8_t buf[PAGE_SIZE], *p;
size_t n;
*crc = ~0;
while ((n = read(fd, buf, sizeof(buf))) > 0) {
p = &buf[0];
while (n-- > 0)
*crc = crc32_tab[(*crc ^ *p++) & 0xff] ^ (*crc >> 8);
}
*crc = ~*crc;
return (n);
}
static void
demangle(const char *symbol, char *buf, size_t len)
{
#ifndef NO_CXA_DEMANGLE
char *dembuf;
if (symbol[0] == '_' && symbol[1] == 'Z' && symbol[2]) {
dembuf = __cxa_demangle(symbol, NULL, NULL, NULL);
if (!dembuf)
goto fail;
strlcpy(buf, dembuf, len);
free(dembuf);
return;
}
fail:
#endif /* NO_CXA_DEMANGLE */
strlcpy(buf, symbol, len);
}
struct symsort_thunk {
Elf *e;
struct symtab *symtab;
};
static int
symvalcmp(void *_thunk, const void *a1, const void *a2)
{
GElf_Sym sym1, sym2;
struct symsort_thunk *thunk;
const char *s1, *s2;
u_int i1, i2;
int bind1, bind2;
i1 = *(const u_int *)a1;
i2 = *(const u_int *)a2;
thunk = _thunk;
(void)gelf_getsym(thunk->symtab->data, i1, &sym1);
(void)gelf_getsym(thunk->symtab->data, i2, &sym2);
if (sym1.st_value != sym2.st_value)
return (sym1.st_value < sym2.st_value ? -1 : 1);
/* Prefer non-local symbols. */
bind1 = GELF_ST_BIND(sym1.st_info);
bind2 = GELF_ST_BIND(sym2.st_info);
if (bind1 != bind2) {
if (bind1 == STB_LOCAL && bind2 != STB_LOCAL)
return (-1);
if (bind1 != STB_LOCAL && bind2 == STB_LOCAL)
return (1);
}
s1 = elf_strptr(thunk->e, thunk->symtab->stridx, sym1.st_name);
s2 = elf_strptr(thunk->e, thunk->symtab->stridx, sym2.st_name);
if (s1 != NULL && s2 != NULL) {
/* Prefer symbols without a leading '$'. */
if (*s1 == '$')
return (-1);
if (*s2 == '$')
return (1);
/* Prefer symbols with fewer leading underscores. */
for (; *s1 == '_' && *s2 == '_'; s1++, s2++)
;
if (*s1 == '_')
return (-1);
if (*s2 == '_')
return (1);
}
return (0);
}
static int
load_symtab(Elf *e, struct symtab *symtab, u_long sh_type)
{
GElf_Ehdr ehdr;
GElf_Shdr shdr;
struct symsort_thunk thunk;
Elf_Scn *scn;
u_int nsyms;
if (gelf_getehdr(e, &ehdr) == NULL)
return (-1);
scn = NULL;
while ((scn = elf_nextscn(e, scn)) != NULL) {
(void)gelf_getshdr(scn, &shdr);
if (shdr.sh_type == sh_type)
break;
}
if (scn == NULL)
return (-1);
nsyms = shdr.sh_size / shdr.sh_entsize;
if (nsyms > (1 << 20))
return (-1);
if ((symtab->data = elf_getdata(scn, NULL)) == NULL)
return (-1);
symtab->index = calloc(nsyms, sizeof(u_int));
if (symtab->index == NULL)
return (-1);
for (u_int i = 0; i < nsyms; i++)
symtab->index[i] = i;
symtab->nsyms = nsyms;
symtab->stridx = shdr.sh_link;
thunk.e = e;
thunk.symtab = symtab;
qsort_r(symtab->index, nsyms, sizeof(u_int), &thunk, symvalcmp);
return (0);
}
static void
load_symtabs(struct file_info *file)
{
file->symtab.nsyms = file->dynsymtab.nsyms = 0;
(void)load_symtab(file->elf, &file->symtab, SHT_SYMTAB);
(void)load_symtab(file->elf, &file->dynsymtab, SHT_DYNSYM);
}
static int
open_debug_file(char *path, const char *debugfile, uint32_t crc)
{
size_t n;
uint32_t compcrc;
int fd;
fd = -1;
if ((n = strlcat(path, "/", PATH_MAX)) >= PATH_MAX)
return (fd);
if (strlcat(path, debugfile, PATH_MAX) >= PATH_MAX)
goto out;
if ((fd = open(path, O_RDONLY | O_CLOEXEC)) < 0)
goto out;
if (crc32_file(fd, &compcrc) != 0 || crc != compcrc) {
DPRINTFX("ERROR: CRC32 mismatch for %s", path);
(void)close(fd);
fd = -1;
}
out:
path[n] = '\0';
return (fd);
}
/*
* Obtain an ELF descriptor for the specified mapped object. If a GNU debuglink
* section is present, a descriptor for the corresponding debug file is
* returned.
*/
static int
open_object(struct map_info *mapping)
{
char path[PATH_MAX];
GElf_Shdr shdr;
Elf *e, *e2;
Elf_Data *data;
Elf_Scn *scn;
struct file_info *file;
prmap_t *map;
const char *debugfile, *scnname;
size_t ndx;
uint32_t crc;
int fd, fd2;
if (mapping->map.pr_mapname[0] == '\0')
return (-1); /* anonymous object */
if (mapping->file->elf != NULL)
return (0); /* already loaded */
file = mapping->file;
map = &mapping->map;
if ((fd = open(map->pr_mapname, O_RDONLY | O_CLOEXEC)) < 0) {
DPRINTF("ERROR: open %s failed", map->pr_mapname);
return (-1);
}
if ((e = elf_begin(fd, ELF_C_READ, NULL)) == NULL) {
DPRINTFX("ERROR: elf_begin() failed: %s", elf_errmsg(-1));
goto err;
}
if (gelf_getehdr(e, &file->ehdr) != &file->ehdr) {
DPRINTFX("ERROR: elf_getehdr() failed: %s", elf_errmsg(-1));
goto err;
}
scn = NULL;
while ((scn = elf_nextscn(e, scn)) != NULL) {
if (gelf_getshdr(scn, &shdr) != &shdr) {
DPRINTFX("ERROR: gelf_getshdr failed: %s",
elf_errmsg(-1));
goto err;
}
if (shdr.sh_type != SHT_PROGBITS)
continue;
if (elf_getshdrstrndx(e, &ndx) != 0) {
DPRINTFX("ERROR: elf_getshdrstrndx failed: %s",
elf_errmsg(-1));
goto err;
}
if ((scnname = elf_strptr(e, ndx, shdr.sh_name)) == NULL)
continue;
if (strcmp(scnname, ".gnu_debuglink") == 0)
break;
}
if (scn == NULL)
goto internal;
if ((data = elf_getdata(scn, NULL)) == NULL) {
DPRINTFX("ERROR: elf_getdata failed: %s", elf_errmsg(-1));
goto err;
}
/*
* The data contains a null-terminated file name followed by a 4-byte
* CRC.
*/
if (data->d_size < sizeof(crc) + 1) {
DPRINTFX("ERROR: debuglink section is too small (%zd bytes)",
data->d_size);
goto internal;
}
if (strnlen(data->d_buf, data->d_size) >= data->d_size - sizeof(crc)) {
DPRINTFX("ERROR: no null-terminator in gnu_debuglink section");
goto internal;
}
debugfile = data->d_buf;
memcpy(&crc, (char *)data->d_buf + data->d_size - sizeof(crc),
sizeof(crc));
/*
* Search for the debug file using the algorithm described in the gdb
* documentation:
* - look in the directory containing the object,
* - look in the subdirectory ".debug" of the directory containing the
* object,
* - look in the global debug directories (currently /usr/lib/debug).
*/
(void)strlcpy(path, map->pr_mapname, sizeof(path));
(void)dirname(path);
if ((fd2 = open_debug_file(path, debugfile, crc)) >= 0)
goto external;
if (strlcat(path, "/.debug", sizeof(path)) < sizeof(path) &&
(fd2 = open_debug_file(path, debugfile, crc)) >= 0)
goto external;
(void)snprintf(path, sizeof(path), PATH_DEBUG_DIR);
if (strlcat(path, map->pr_mapname, sizeof(path)) < sizeof(path)) {
(void)dirname(path);
if ((fd2 = open_debug_file(path, debugfile, crc)) >= 0)
goto external;
}
internal:
/* We didn't find a debug file, just return the object's descriptor. */
file->elf = e;
file->fd = fd;
load_symtabs(file);
return (0);
external:
if ((e2 = elf_begin(fd2, ELF_C_READ, NULL)) == NULL) {
DPRINTFX("ERROR: elf_begin failed: %s", elf_errmsg(-1));
(void)close(fd2);
goto err;
}
(void)elf_end(e);
(void)close(fd);
file->elf = e2;
file->fd = fd2;
load_symtabs(file);
return (0);
err:
if (e != NULL)
(void)elf_end(e);
(void)close(fd);
return (-1);
}
char *
proc_objname(struct proc_handle *p, uintptr_t addr, char *objname,
size_t objnamesz)
{
prmap_t *map;
size_t i;
if (p->nmappings == 0)
if (proc_rdagent(p) == NULL)
return (NULL);
for (i = 0; i < p->nmappings; i++) {
map = &p->mappings[i].map;
if (addr >= map->pr_vaddr &&
addr < map->pr_vaddr + map->pr_size) {
strlcpy(objname, map->pr_mapname, objnamesz);
return (objname);
}
}
return (NULL);
}
int
proc_iter_objs(struct proc_handle *p, proc_map_f *func, void *cd)
{
char last[MAXPATHLEN], path[MAXPATHLEN], *base;
prmap_t *map;
size_t i;
int error;
if (p->nmappings == 0)
if (proc_rdagent(p) == NULL)
return (-1);
error = 0;
memset(last, 0, sizeof(last));
for (i = 0; i < p->nmappings; i++) {
map = &p->mappings[i].map;
strlcpy(path, map->pr_mapname, sizeof(path));
base = basename(path);
/*
* We shouldn't call the callback twice with the same object.
* To do that we are assuming the fact that if there are
* repeated object names (i.e. different mappings for the
* same object) they occur next to each other.
*/
if (strcmp(base, last) == 0)
continue;
if ((error = (*func)(cd, map, base)) != 0)
break;
strlcpy(last, path, sizeof(last));
}
return (error);
}
static struct map_info *
_proc_addr2map(struct proc_handle *p, uintptr_t addr)
{
struct map_info *mapping;
size_t i;
if (p->nmappings == 0)
if (proc_rdagent(p) == NULL)
return (NULL);
for (i = 0; i < p->nmappings; i++) {
mapping = &p->mappings[i];
if (addr >= mapping->map.pr_vaddr &&
addr < mapping->map.pr_vaddr + mapping->map.pr_size)
return (mapping);
}
return (NULL);
}
prmap_t *
proc_addr2map(struct proc_handle *p, uintptr_t addr)
{
return (&_proc_addr2map(p, addr)->map);
}
/*
* Look up the symbol at addr using a binary search, returning a copy of the
* symbol and its name.
*/
static int
lookup_symbol_by_addr(Elf *e, struct symtab *symtab, uintptr_t addr,
const char **namep, GElf_Sym *symp)
{
GElf_Sym sym;
Elf_Data *data;
const char *s;
u_int i, min, max, mid;
if (symtab->nsyms == 0)
return (ENOENT);
data = symtab->data;
min = 0;
max = symtab->nsyms - 1;
while (min <= max) {
mid = (max + min) / 2;
(void)gelf_getsym(data, symtab->index[mid], &sym);
if (addr >= sym.st_value && addr < sym.st_value + sym.st_size)
break;
if (addr < sym.st_value)
max = mid - 1;
else
min = mid + 1;
}
if (min > max)
return (ENOENT);
/*
* Advance until we find the matching symbol with largest index.
*/
for (i = mid; i < symtab->nsyms; i++) {
(void)gelf_getsym(data, symtab->index[i], &sym);
if (addr < sym.st_value || addr >= sym.st_value + sym.st_size)
break;
}
(void)gelf_getsym(data, symtab->index[i - 1], symp);
s = elf_strptr(e, symtab->stridx, symp->st_name);
if (s != NULL && namep != NULL)
*namep = s;
return (0);
}
int
proc_addr2sym(struct proc_handle *p, uintptr_t addr, char *name,
size_t namesz, GElf_Sym *symcopy)
{
struct file_info *file;
struct map_info *mapping;
const char *s;
uintptr_t off;
int error;
if ((mapping = _proc_addr2map(p, addr)) == NULL) {
DPRINTFX("ERROR: proc_addr2map failed to resolve 0x%jx", addr);
return (-1);
}
if (open_object(mapping) != 0) {
DPRINTFX("ERROR: failed to open object %s",
mapping->map.pr_mapname);
return (-1);
}
file = mapping->file;
off = file->ehdr.e_type == ET_DYN ?
mapping->map.pr_vaddr - mapping->map.pr_offset : 0;
if (addr < off)
return (ENOENT);
addr -= off;
error = lookup_symbol_by_addr(file->elf, &file->dynsymtab, addr, &s,
symcopy);
if (error == ENOENT)
error = lookup_symbol_by_addr(file->elf, &file->symtab, addr,
&s, symcopy);
if (error == 0) {
symcopy->st_value += off;
demangle(s, name, namesz);
}
return (error);
}
static struct map_info *
_proc_name2map(struct proc_handle *p, const char *name)
{
char path[MAXPATHLEN], *base;
struct map_info *mapping;
size_t i, len;
if ((len = strlen(name)) == 0)
return (NULL);
if (p->nmappings == 0)
if (proc_rdagent(p) == NULL)
return (NULL);
for (i = 0; i < p->nmappings; i++) {
mapping = &p->mappings[i];
(void)strlcpy(path, mapping->map.pr_mapname, sizeof(path));
base = basename(path);
if (strcmp(base, name) == 0)
return (mapping);
}
/* If we didn't find a match, try matching prefixes of the basename. */
for (i = 0; i < p->nmappings; i++) {
strlcpy(path, p->mappings[i].map.pr_mapname, sizeof(path));
base = basename(path);
if (strncmp(base, name, len) == 0)
return (&p->mappings[i]);
}
if (strcmp(name, "a.out") == 0)
return (_proc_addr2map(p,
p->mappings[p->exec_map].map.pr_vaddr));
return (NULL);
}
prmap_t *
proc_name2map(struct proc_handle *p, const char *name)
{
return (&_proc_name2map(p, name)->map);
}
/*
* Look up the symbol with the given name and return a copy of it.
*/
static int
lookup_symbol_by_name(Elf *elf, struct symtab *symtab, const char *symbol,
GElf_Sym *symcopy, prsyminfo_t *si)
{
GElf_Sym sym;
Elf_Data *data;
char *s;
int i;
if (symtab->nsyms == 0)
return (ENOENT);
data = symtab->data;
for (i = 0; gelf_getsym(data, i, &sym) != NULL; i++) {
s = elf_strptr(elf, symtab->stridx, sym.st_name);
if (s != NULL && strcmp(s, symbol) == 0) {
memcpy(symcopy, &sym, sizeof(*symcopy));
if (si != NULL)
si->prs_id = i;
return (0);
}
}
return (ENOENT);
}
int
proc_name2sym(struct proc_handle *p, const char *object, const char *symbol,
GElf_Sym *symcopy, prsyminfo_t *si)
{
struct file_info *file;
struct map_info *mapping;
uintptr_t off;
int error;
if ((mapping = _proc_name2map(p, object)) == NULL) {
DPRINTFX("ERROR: proc_name2map failed to resolve %s", object);
return (-1);
}
if (open_object(mapping) != 0) {
DPRINTFX("ERROR: failed to open object %s",
mapping->map.pr_mapname);
return (-1);
}
file = mapping->file;
off = file->ehdr.e_type == ET_DYN ?
mapping->map.pr_vaddr - mapping->map.pr_offset : 0;
error = lookup_symbol_by_name(file->elf, &file->dynsymtab, symbol,
symcopy, si);
if (error == ENOENT)
error = lookup_symbol_by_name(file->elf, &file->symtab, symbol,
symcopy, si);
if (error == 0)
symcopy->st_value += off;
return (error);
}
ctf_file_t *
proc_name2ctf(struct proc_handle *p, const char *name)
{
#ifndef NO_CTF
ctf_file_t *ctf;
prmap_t *map;
int error;
if ((map = proc_name2map(p, name)) == NULL)
return (NULL);
ctf = ctf_open(map->pr_mapname, &error);
return (ctf);
#else
(void)p;
(void)name;
return (NULL);
#endif
}
int
proc_iter_symbyaddr(struct proc_handle *p, const char *object, int which,
int mask, proc_sym_f *func, void *cd)
{
GElf_Sym sym;
struct file_info *file;
struct map_info *mapping;
struct symtab *symtab;
const char *s;
int error, i;
if ((mapping = _proc_name2map(p, object)) == NULL) {
DPRINTFX("ERROR: proc_name2map failed to resolve %s", object);
return (-1);
}
if (open_object(mapping) != 0) {
DPRINTFX("ERROR: failed to open object %s",
mapping->map.pr_mapname);
return (-1);
}
file = mapping->file;
symtab = which == PR_SYMTAB ? &file->symtab : &file->dynsymtab;
if (symtab->nsyms == 0)
return (-1);
error = 0;
for (i = 0; gelf_getsym(symtab->data, i, &sym) != NULL; i++) {
if (GELF_ST_BIND(sym.st_info) == STB_LOCAL &&
(mask & BIND_LOCAL) == 0)
continue;
if (GELF_ST_BIND(sym.st_info) == STB_GLOBAL &&
(mask & BIND_GLOBAL) == 0)
continue;
if (GELF_ST_BIND(sym.st_info) == STB_WEAK &&
(mask & BIND_WEAK) == 0)
continue;
if (GELF_ST_TYPE(sym.st_info) == STT_NOTYPE &&
(mask & TYPE_NOTYPE) == 0)
continue;
if (GELF_ST_TYPE(sym.st_info) == STT_OBJECT &&
(mask & TYPE_OBJECT) == 0)
continue;
if (GELF_ST_TYPE(sym.st_info) == STT_FUNC &&
(mask & TYPE_FUNC) == 0)
continue;
if (GELF_ST_TYPE(sym.st_info) == STT_SECTION &&
(mask & TYPE_SECTION) == 0)
continue;
if (GELF_ST_TYPE(sym.st_info) == STT_FILE &&
(mask & TYPE_FILE) == 0)
continue;
s = elf_strptr(file->elf, symtab->stridx, sym.st_name);
if (file->ehdr.e_type == ET_DYN)
sym.st_value += mapping->map.pr_vaddr;
if ((error = (*func)(cd, &sym, s)) != 0)
break;
}
return (error);
}