freebsd-dev/lib/librtld_db/rtld_db.c
Chuck Silvers dfd00261c9 librtld_db: Handle shlibs with discontiguous mappings.
Some shared libraries specify mappings that leave a gap (actually a
MAP_GUARD mapping) in between the file mappings (libcrypto.so was
the one I found), and this would cause rd_loadobj_iter() to report
the mapping info incorrectly, leaving out rdl_path and misreporting
rdl_offset for file mappings after the gap.  Fix rd_loadobj_iter()
to handle this situation.

Reviewed by:	markj
Sponsored by:	Netflix
Differential Revision:	https://reviews.freebsd.org/D32950
2021-12-03 11:07:30 -08:00

410 lines
8.5 KiB
C

/*-
* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
*
* Copyright (c) 2010 The FreeBSD Foundation
* All rights reserved.
*
* This software was 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/param.h>
#include <sys/sysctl.h>
#include <sys/user.h>
#include <assert.h>
#include <err.h>
#include <fcntl.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <machine/elf.h>
#include <libelf.h>
#include <libproc.h>
#include <libprocstat.h>
#include <libutil.h>
#include "rtld_db.h"
static int _librtld_db_debug = 0;
#define DPRINTF(...) do { \
if (_librtld_db_debug) { \
fprintf(stderr, "librtld_db: DEBUG: "); \
fprintf(stderr, __VA_ARGS__); \
} \
} while (0)
void
rd_delete(rd_agent_t *rdap)
{
if (rdap->rda_procstat != NULL)
procstat_close(rdap->rda_procstat);
free(rdap);
}
const char *
rd_errstr(rd_err_e rderr)
{
switch (rderr) {
case RD_ERR:
return "generic error";
case RD_OK:
return "no error";
case RD_NOCAPAB:
return "capability not supported";
case RD_DBERR:
return "database error";
case RD_NOBASE:
return "NOBASE";
case RD_NOMAPS:
return "NOMAPS";
default:
return "unknown error";
}
}
rd_err_e
rd_event_addr(rd_agent_t *rdap, rd_event_e event, rd_notify_t *notify)
{
rd_err_e ret;
DPRINTF("%s rdap %p event %d notify %p\n", __func__, rdap, event,
notify);
ret = RD_OK;
switch (event) {
case RD_NONE:
break;
case RD_PREINIT:
notify->type = RD_NOTIFY_BPT;
notify->u.bptaddr = rdap->rda_preinit_addr;
break;
case RD_POSTINIT:
notify->type = RD_NOTIFY_BPT;
notify->u.bptaddr = rdap->rda_postinit_addr;
break;
case RD_DLACTIVITY:
notify->type = RD_NOTIFY_BPT;
notify->u.bptaddr = rdap->rda_dlactivity_addr;
break;
default:
ret = RD_ERR;
break;
}
return (ret);
}
rd_err_e
rd_event_enable(rd_agent_t *rdap __unused, int onoff)
{
DPRINTF("%s onoff %d\n", __func__, onoff);
return (RD_OK);
}
rd_err_e
rd_event_getmsg(rd_agent_t *rdap __unused, rd_event_msg_t *msg)
{
DPRINTF("%s\n", __func__);
msg->type = RD_POSTINIT;
msg->u.state = RD_CONSISTENT;
return (RD_OK);
}
rd_err_e
rd_init(int version)
{
char *debug = NULL;
if (version == RD_VERSION) {
debug = getenv("LIBRTLD_DB_DEBUG");
_librtld_db_debug = debug ? atoi(debug) : 0;
return (RD_OK);
} else
return (RD_NOCAPAB);
}
rd_err_e
rd_loadobj_iter(rd_agent_t *rdap, rl_iter_f *cb, void *clnt_data)
{
struct kinfo_vmentry *kves, *kve;
const char *path;
uint64_t fileid;
rd_loadobj_t rdl;
rd_err_e ret;
uintptr_t base;
uint32_t offset;
int cnt, i;
DPRINTF("%s\n", __func__);
if ((kves = kinfo_getvmmap(proc_getpid(rdap->rda_php), &cnt)) == NULL) {
warn("ERROR: kinfo_getvmmap() failed");
return (RD_ERR);
}
base = 0;
fileid = 0;
path = NULL;
ret = RD_OK;
for (i = 0; i < cnt; i++) {
kve = &kves[i];
/*
* Cache the base offset of the file mapping. The kve_offset
* field gives the file offset of a particular mapping into the
* file, but we want the mapping offset relative to the base
* mapping.
*/
if (kve->kve_type == KVME_TYPE_VNODE) {
if (kve->kve_vn_fileid != fileid) {
base = kve->kve_start;
fileid = kve->kve_vn_fileid;
}
path = kve->kve_path;
offset = kve->kve_start - base;
} else {
path = NULL;
offset = 0;
}
memset(&rdl, 0, sizeof(rdl));
/*
* Map the kinfo_vmentry struct to the rd_loadobj structure.
*/
rdl.rdl_saddr = kve->kve_start;
rdl.rdl_eaddr = kve->kve_end;
rdl.rdl_offset = offset;
if (kve->kve_protection & KVME_PROT_READ)
rdl.rdl_prot |= RD_RDL_R;
if (kve->kve_protection & KVME_PROT_WRITE)
rdl.rdl_prot |= RD_RDL_W;
if (kve->kve_protection & KVME_PROT_EXEC)
rdl.rdl_prot |= RD_RDL_X;
if (path != NULL)
strlcpy(rdl.rdl_path, path, sizeof(rdl.rdl_path));
if ((*cb)(&rdl, clnt_data) != 0) {
ret = RD_ERR;
break;
}
}
free(kves);
return (ret);
}
void
rd_log(const int onoff)
{
DPRINTF("%s\n", __func__);
(void)onoff;
}
rd_agent_t *
rd_new(struct proc_handle *php)
{
rd_agent_t *rdap;
rdap = malloc(sizeof(*rdap));
if (rdap == NULL)
return (NULL);
memset(rdap, 0, sizeof(rd_agent_t));
rdap->rda_php = php;
rdap->rda_procstat = procstat_open_sysctl();
if (rd_reset(rdap) != RD_OK) {
rd_delete(rdap);
rdap = NULL;
}
return (rdap);
}
rd_err_e
rd_objpad_enable(rd_agent_t *rdap, size_t padsize)
{
DPRINTF("%s\n", __func__);
(void)rdap;
(void)padsize;
return (RD_ERR);
}
rd_err_e
rd_plt_resolution(rd_agent_t *rdap, uintptr_t pc, struct proc *proc,
uintptr_t plt_base, rd_plt_info_t *rpi)
{
DPRINTF("%s\n", __func__);
(void)rdap;
(void)pc;
(void)proc;
(void)plt_base;
(void)rpi;
return (RD_ERR);
}
static int
rtld_syms(rd_agent_t *rdap, const char *rtldpath, u_long base)
{
GElf_Shdr shdr;
GElf_Sym sym;
Elf *e;
Elf_Data *data;
Elf_Scn *scn;
const char *symname;
Elf64_Word strscnidx;
int fd, i, ret;
ret = 1;
e = NULL;
fd = open(rtldpath, O_RDONLY);
if (fd < 0)
goto err;
if (elf_version(EV_CURRENT) == EV_NONE)
goto err;
e = elf_begin(fd, ELF_C_READ, NULL);
if (e == NULL)
goto err;
scn = NULL;
while ((scn = elf_nextscn(e, scn)) != NULL) {
gelf_getshdr(scn, &shdr);
if (shdr.sh_type == SHT_DYNSYM)
break;
}
if (scn == NULL)
goto err;
strscnidx = shdr.sh_link;
data = elf_getdata(scn, NULL);
if (data == NULL)
goto err;
for (i = 0; gelf_getsym(data, i, &sym) != NULL; i++) {
if (GELF_ST_TYPE(sym.st_info) != STT_FUNC ||
GELF_ST_BIND(sym.st_info) != STB_GLOBAL)
continue;
symname = elf_strptr(e, strscnidx, sym.st_name);
if (symname == NULL)
continue;
if (strcmp(symname, "r_debug_state") == 0) {
rdap->rda_preinit_addr = sym.st_value + base;
rdap->rda_dlactivity_addr = sym.st_value + base;
} else if (strcmp(symname, "_r_debug_postinit") == 0) {
rdap->rda_postinit_addr = sym.st_value + base;
}
}
if (rdap->rda_preinit_addr != 0 &&
rdap->rda_postinit_addr != 0 &&
rdap->rda_dlactivity_addr != 0)
ret = 0;
err:
if (e != NULL)
(void)elf_end(e);
if (fd >= 0)
(void)close(fd);
return (ret);
}
rd_err_e
rd_reset(rd_agent_t *rdap)
{
struct kinfo_proc *kp;
struct kinfo_vmentry *kve;
Elf_Auxinfo *auxv;
const char *rtldpath;
u_long base;
rd_err_e rderr;
int count, i;
kp = NULL;
auxv = NULL;
kve = NULL;
rderr = RD_ERR;
kp = procstat_getprocs(rdap->rda_procstat, KERN_PROC_PID,
proc_getpid(rdap->rda_php), &count);
if (kp == NULL)
return (RD_ERR);
assert(count == 1);
auxv = procstat_getauxv(rdap->rda_procstat, kp, &count);
if (auxv == NULL)
goto err;
base = 0;
for (i = 0; i < count; i++) {
if (auxv[i].a_type == AT_BASE) {
base = auxv[i].a_un.a_val;
break;
}
}
if (i == count)
goto err;
rtldpath = NULL;
kve = procstat_getvmmap(rdap->rda_procstat, kp, &count);
if (kve == NULL)
goto err;
for (i = 0; i < count; i++) {
if (kve[i].kve_start == base) {
rtldpath = kve[i].kve_path;
break;
}
}
if (i == count)
goto err;
if (rtld_syms(rdap, rtldpath, base) != 0)
goto err;
rderr = RD_OK;
err:
if (kve != NULL)
procstat_freevmmap(rdap->rda_procstat, kve);
if (auxv != NULL)
procstat_freeauxv(rdap->rda_procstat, auxv);
if (kp != NULL)
procstat_freeprocs(rdap->rda_procstat, kp);
return (rderr);
}