/*
* Copyright (c) 2003, 2013, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*
*/
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/ptrace.h>
#include <sys/param.h>
#include <sys/user.h>
#include <elf.h>
#include <sys/elf_common.h>
#include <sys/link_elf.h>
#include <libutil.h>
#include "libproc_impl.h"
#include "elfmacros.h"
// This file has the libproc implementation specific to live process
// For core files, refer to ps_core.c
static inline uintptr_t align(uintptr_t ptr, size_t size) {
return (ptr & ~(size - 1));
}
// ---------------------------------------------
// ptrace functions
// ---------------------------------------------
// read "size" bytes of data from "addr" within the target process.
// unlike the standard ptrace() function, process_read_data() can handle
// unaligned address - alignment check, if required, should be done
// before calling process_read_data.
static bool process_read_data(struct ps_prochandle* ph, uintptr_t addr, char *buf, size_t size) {
int rslt;
size_t i, words;
uintptr_t end_addr = addr + size;
uintptr_t aligned_addr = align(addr, sizeof(int));
if (aligned_addr != addr) {
char *ptr = (char *)&rslt;
errno = 0;
rslt = ptrace(PT_READ_D, ph->pid, (caddr_t) aligned_addr, 0);
if (errno) {
print_debug("ptrace(PT_READ_D, ..) failed for %d bytes @ %lx\n", size, addr);
return false;
}
for (; aligned_addr != addr; aligned_addr++, ptr++);
for (; ((intptr_t)aligned_addr % sizeof(int)) && aligned_addr < end_addr;
aligned_addr++)
*(buf++) = *(ptr++);
}
words = (end_addr - aligned_addr) / sizeof(int);
// assert((intptr_t)aligned_addr % sizeof(int) == 0);
for (i = 0; i < words; i++) {
errno = 0;
rslt = ptrace(PT_READ_D, ph->pid, (caddr_t) aligned_addr, 0);
if (errno) {
print_debug("ptrace(PT_READ_D, ..) failed for %d bytes @ %lx\n", size, addr);
return false;
}
*(int *)buf = rslt;
buf += sizeof(int);
aligned_addr += sizeof(int);
}
if (aligned_addr != end_addr) {
char *ptr = (char *)&rslt;
errno = 0;
rslt = ptrace(PT_READ_D, ph->pid, (caddr_t) aligned_addr, 0);
if (errno) {
print_debug("ptrace(PT_READ_D, ..) failed for %d bytes @ %lx\n", size, addr);
return false;
}
for (; aligned_addr != end_addr; aligned_addr++)
*(buf++) = *(ptr++);
}
return true;
}
// null implementation for write
static bool process_write_data(struct ps_prochandle* ph,
uintptr_t addr, const char *buf , size_t size) {
return false;
}
// "user" should be a pointer to a reg
static bool process_get_lwp_regs(struct ps_prochandle* ph, pid_t pid, struct reg *user) {
// we have already attached to all thread 'pid's, just use ptrace call
// to get regset now. Note that we don't cache regset upfront for processes.
if (ptrace(PT_GETREGS, pid, (caddr_t) user, 0) < 0) {
print_debug("ptrace(PTRACE_GETREGS, ...) failed for lwp %d\n", pid);
return false;
}
return true;
}
// fill in ptrace_lwpinfo for lid
static bool process_get_lwp_info(struct ps_prochandle *ph, lwpid_t lwp_id, void *linfo) {
errno = 0;
ptrace(PT_LWPINFO, lwp_id, linfo, sizeof(struct ptrace_lwpinfo));
return (errno == 0)? true: false;
}
static bool ptrace_continue(pid_t pid, int signal) {
// pass the signal to the process so we don't swallow it
if (ptrace(PTRACE_CONT, pid, NULL, signal) < 0) {
print_debug("ptrace(PTRACE_CONT, ..) failed for %d\n", pid);
return false;
}
return true;
}
// waits until the ATTACH has stopped the process
// by signal SIGSTOP
static bool ptrace_waitpid(pid_t pid) {
int ret;
int status;
do {
// Wait for debuggee to stop.
ret = waitpid(pid, &status, 0);
if (ret >= 0) {
if (WIFSTOPPED(status)) {
// Any signal will stop the thread, make sure it is SIGSTOP. Otherwise SIGSTOP
// will still be pending and delivered when the process is DETACHED and the process
// will go to sleep.
if (WSTOPSIG(status) == SIGSTOP) {
// Debuggee stopped by SIGSTOP.
return true;
}
if (!ptrace_continue(pid, WSTOPSIG(status))) {
print_error("Failed to correctly attach to VM. VM might HANG! [PTRACE_CONT failed, stopped by %d]\n", WSTOPSIG(status));
return false;
}
} else {
print_debug("waitpid(): Child process exited/terminated (status = 0x%x)\n", status);
return false;
}
} else {
switch (errno) {
case EINTR:
continue;
break;
case ECHILD:
print_debug("waitpid() failed. Child process pid (%d) does not exist \n", pid);
break;
case EINVAL:
print_debug("waitpid() failed. Invalid options argument.\n");
break;
default:
print_debug("waitpid() failed. Unexpected error %d\n",errno);
}
return false;
}
} while(true);
}
// attach to a process/thread specified by "pid"
static bool ptrace_attach(pid_t pid) {
if (ptrace(PT_ATTACH, pid, NULL, 0) < 0) {
print_debug("ptrace(PTRACE_ATTACH, ..) failed for %d\n", pid);
return false;
} else {
return ptrace_waitpid(pid);
}
}
// -------------------------------------------------------
// functions for obtaining library information
// -------------------------------------------------------
// callback for read_thread_info
static bool add_new_thread(struct ps_prochandle* ph, pthread_t pthread_id, lwpid_t lwp_id) {
return add_thread_info(ph, pthread_id, lwp_id) != NULL;
}
#if defined(__FreeBSD__) && __FreeBSD_version < 701000
/*
* TEXT_START_ADDR from binutils/ld/emulparams/<arch_spec>.sh
* Not the most robust but good enough.
*/
#if defined(amd64) || defined(x86_64)
#define TEXT_START_ADDR 0x400000
#elif defined(i386)
#define TEXT_START_ADDR 0x8048000
#else
#error TEXT_START_ADDR not defined
#endif
#define BUF_SIZE (PATH_MAX + NAME_MAX + 1)
uintptr_t linkmap_addr(struct ps_prochandle *ph) {
uintptr_t ehdr_addr, phdr_addr, dyn_addr, dmap_addr, lmap_addr;
ELF_EHDR ehdr;
ELF_PHDR *phdrs, *phdr;
ELF_DYN *dyns, *dyn;
struct r_debug dmap;
unsigned long hdrs_size;
unsigned int i;
/* read ELF_EHDR at TEXT_START_ADDR and validate */
ehdr_addr = (uintptr_t)TEXT_START_ADDR;
if (process_read_data(ph, ehdr_addr, (char *)&ehdr, sizeof(ehdr)) != true) {
print_debug("process_read_data failed for ehdr_addr %p\n", ehdr_addr);
return (0);
}
if (!IS_ELF(ehdr) ||
ehdr.e_ident[EI_CLASS] != ELF_TARG_CLASS ||
ehdr.e_ident[EI_DATA] != ELF_TARG_DATA ||
ehdr.e_ident[EI_VERSION] != EV_CURRENT ||
ehdr.e_phentsize != sizeof(ELF_PHDR) ||
ehdr.e_version != ELF_TARG_VER ||
ehdr.e_machine != ELF_TARG_MACH) {
print_debug("not an ELF_EHDR at %p\n", ehdr_addr);
return (0);
}
/* allocate space for all ELF_PHDR's and read */
phdr_addr = ehdr_addr + ehdr.e_phoff;
hdrs_size = ehdr.e_phnum * sizeof(ELF_PHDR);
if ((phdrs = malloc(hdrs_size)) == NULL)
return (0);
if (process_read_data(ph, phdr_addr, (char *)phdrs, hdrs_size) != true) {
print_debug("process_read_data failed for phdr_addr %p\n", phdr_addr);
return (0);
}
/* find PT_DYNAMIC section */
for (i = 0, phdr = phdrs; i < ehdr.e_phnum; i++, phdr++) {
if (phdr->p_type == PT_DYNAMIC)
break;
}
if (i >= ehdr.e_phnum) {
print_debug("PT_DYNAMIC section not found!\n");
free(phdrs);
return (0);
}
/* allocate space and read in ELF_DYN headers */
dyn_addr = phdr->p_vaddr;
hdrs_size = phdr->p_memsz;
free(phdrs);
if ((dyns = malloc(hdrs_size)) == NULL)
return (0);
if (process_read_data(ph, dyn_addr, (char *)dyns, hdrs_size) != true) {
print_debug("process_read_data failed for dyn_addr %p\n", dyn_addr);
free(dyns);
return (0);
}
/* find DT_DEBUG */
dyn = dyns;
while (dyn->d_tag != DT_DEBUG && dyn->d_tag != DT_NULL) {
dyn++;
}
if (dyn->d_tag != DT_DEBUG) {
print_debug("failed to find DT_DEBUG\n");
free(dyns);
return (0);
}
/* read struct r_debug into dmap */
dmap_addr = (uintptr_t)dyn->d_un.d_ptr;
free(dyns);
if (process_read_data(ph, dmap_addr, (char *)&dmap, sizeof(dmap)) != true) {
print_debug("process_read_data failed for dmap_addr %p\n", dmap_addr);
return (0);
}
lmap_addr = (uintptr_t)dmap.r_map;
return (lmap_addr);
}
#endif // __FreeBSD__ && __FreeBSD_version < 701000
static bool read_lib_info(struct ps_prochandle* ph) {
#if defined(__FreeBSD__) && __FreeBSD_version >= 701000
struct kinfo_vmentry *freep, *kve;
int i, cnt;
freep = kinfo_getvmmap(ph->pid, &cnt);
if (freep == NULL) {
print_debug("can't get vm map for pid\n", ph->pid);
return false;
}
for (i = 0; i < cnt; i++) {
kve = &freep[i];
if ((kve->kve_flags & KVME_FLAG_COW) &&
kve->kve_path != NULL &&
strlen(kve->kve_path) > 0) {
if (find_lib(ph, kve->kve_path) == false) {
lib_info* lib;
if ((lib = add_lib_info(ph, kve->kve_path,
(uintptr_t) kve->kve_start)) == NULL)
continue; // ignore, add_lib_info prints error
// we don't need to keep the library open, symtab is already
// built. Only for core dump we need to keep the fd open.
close(lib->fd);
lib->fd = -1;
}
}
}
free(freep);
return true;
#else
char *l_name;
struct link_map *lmap;
uintptr_t lmap_addr;
if ((l_name = malloc(BUF_SIZE)) == NULL)
return false;
if ((lmap = malloc(sizeof(*lmap))) == NULL) {
free(l_name);
return false;
}
lmap_addr = linkmap_addr(ph);
if (lmap_addr == 0) {
free(l_name);
free(lmap);
return false;
}
do {
if (process_read_data(ph, lmap_addr, (char *)lmap, sizeof(*lmap)) != true) {
print_debug("process_read_data failed for lmap_addr %p\n", lmap_addr);
free (l_name);
free (lmap);
return false;
}
if (process_read_data(ph, (uintptr_t)lmap->l_name, l_name,
BUF_SIZE) != true) {
print_debug("process_read_data failed for lmap->l_name %p\n",
lmap->l_name);
free (l_name);
free (lmap);
return false;
}
if (find_lib(ph, l_name) == false) {
lib_info* lib;
if ((lib = add_lib_info(ph, l_name,
(uintptr_t) lmap->l_addr)) == NULL)
continue; // ignore, add_lib_info prints error
// we don't need to keep the library open, symtab is already
// built. Only for core dump we need to keep the fd open.
close(lib->fd);
lib->fd = -1;
}
lmap_addr = (uintptr_t)lmap->l_next;
} while (lmap->l_next != NULL);
free (l_name);
free (lmap);
return true;
#endif
}
// detach a given pid
static bool ptrace_detach(pid_t pid) {
if (pid && ptrace(PT_DETACH, pid, (caddr_t)1, 0) < 0) {
print_debug("ptrace(PTRACE_DETACH, ..) failed for %d\n", pid);
return false;
} else {
return true;
}
}
static void process_cleanup(struct ps_prochandle* ph) {
ptrace_detach(ph->pid);
}
static ps_prochandle_ops process_ops = {
.release= process_cleanup,
.p_pread= process_read_data,
.p_pwrite= process_write_data,
.get_lwp_regs= process_get_lwp_regs,
.get_lwp_info= process_get_lwp_info
};
// attach to the process. One and only one exposed stuff
struct ps_prochandle* Pgrab(pid_t pid) {
struct ps_prochandle* ph = NULL;
thread_info* thr = NULL;
if ( (ph = (struct ps_prochandle*) calloc(1, sizeof(struct ps_prochandle))) == NULL) {
print_debug("can't allocate memory for ps_prochandle\n");
return NULL;
}
if (ptrace_attach(pid) != true) {
free(ph);
return NULL;
}
// initialize ps_prochandle
ph->pid = pid;
// initialize vtable
ph->ops = &process_ops;
// read library info and symbol tables, must do this before attaching threads,
// as the symbols in the pthread library will be used to figure out
// the list of threads within the same process.
if (read_lib_info(ph) != true) {
ptrace_detach(pid);
free(ph);
return NULL;
}
// read thread info
read_thread_info(ph, add_new_thread);
return ph;
}