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Sweden-Number/server/ptrace.c

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/*
* Server-side ptrace support
*
* Copyright (C) 1999 Alexandre Julliard
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
*/
#include "config.h"
#include <assert.h>
#include <errno.h>
#include <stdio.h>
#include <signal.h>
#include <stdarg.h>
#include <sys/types.h>
#ifdef HAVE_SYS_PTRACE_H
# include <sys/ptrace.h>
#endif
#ifdef HAVE_SYS_PARAM_H
# include <sys/param.h>
#endif
#ifdef HAVE_SYS_WAIT_H
# include <sys/wait.h>
#endif
#ifdef HAVE_SYS_THR_H
# include <sys/ucontext.h>
# include <sys/thr.h>
#endif
#include <unistd.h>
#include "ntstatus.h"
#define WIN32_NO_STATUS
#include "winternl.h"
#include "file.h"
#include "process.h"
#include "thread.h"
#ifdef USE_PTRACE
#ifndef PTRACE_CONT
#define PTRACE_CONT PT_CONTINUE
#endif
#ifndef PTRACE_SINGLESTEP
#define PTRACE_SINGLESTEP PT_STEP
#endif
#ifndef PTRACE_ATTACH
#define PTRACE_ATTACH PT_ATTACH
#endif
#ifndef PTRACE_DETACH
#define PTRACE_DETACH PT_DETACH
#endif
#ifndef PTRACE_PEEKDATA
#define PTRACE_PEEKDATA PT_READ_D
#endif
#ifndef PTRACE_POKEDATA
#define PTRACE_POKEDATA PT_WRITE_D
#endif
#ifndef PTRACE_PEEKUSER
#define PTRACE_PEEKUSER PT_READ_U
#endif
#ifndef PTRACE_POKEUSER
#define PTRACE_POKEUSER PT_WRITE_U
#endif
#ifdef PT_GETDBREGS
#define PTRACE_GETDBREGS PT_GETDBREGS
#endif
#ifdef PT_SETDBREGS
#define PTRACE_SETDBREGS PT_SETDBREGS
#endif
#ifndef HAVE_SYS_PTRACE_H
#define PT_CONTINUE 0
#define PT_ATTACH 1
#define PT_DETACH 2
#define PT_READ_D 3
#define PT_WRITE_D 4
#define PT_STEP 5
static inline int ptrace(int req, ...) { errno = EPERM; return -1; /*FAIL*/ }
#endif /* HAVE_SYS_PTRACE_H */
/* handle a status returned by wait4 */
static int handle_child_status( struct thread *thread, int pid, int status, int want_sig )
{
if (WIFSTOPPED(status))
{
int sig = WSTOPSIG(status);
if (debug_level && thread)
fprintf( stderr, "%04x: *signal* signal=%d\n", thread->id, sig );
if (sig != want_sig)
{
/* ignore other signals for now */
ptrace( PTRACE_CONT, pid, (caddr_t)1, sig );
}
return sig;
}
if (thread && (WIFSIGNALED(status) || WIFEXITED(status)))
{
thread->unix_pid = -1;
thread->unix_tid = -1;
if (debug_level)
{
if (WIFSIGNALED(status))
fprintf( stderr, "%04x: *exited* signal=%d\n",
thread->id, WTERMSIG(status) );
else
fprintf( stderr, "%04x: *exited* status=%d\n",
thread->id, WEXITSTATUS(status) );
}
}
return 0;
}
/* wait4 wrapper to handle missing __WALL flag in older kernels */
static inline pid_t wait4_wrapper( pid_t pid, int *status, int options, struct rusage *usage )
{
#ifdef __WALL
static int wall_flag = __WALL;
for (;;)
{
pid_t ret = wait4( pid, status, options | wall_flag, usage );
if (ret != -1 || !wall_flag || errno != EINVAL) return ret;
wall_flag = 0;
}
#else
return wait4( pid, status, options, usage );
#endif
}
/* handle a SIGCHLD signal */
void sigchld_callback(void)
{
int pid, status;
for (;;)
{
if (!(pid = wait4_wrapper( -1, &status, WUNTRACED | WNOHANG, NULL ))) break;
if (pid != -1)
{
struct thread *thread = get_thread_from_tid( pid );
if (!thread) thread = get_thread_from_pid( pid );
handle_child_status( thread, pid, status, -1 );
}
else break;
}
}
/* return the Unix pid to use in ptrace calls for a given process */
static int get_ptrace_pid( struct thread *thread )
{
#ifdef linux /* linux always uses thread id */
if (thread->unix_tid != -1) return thread->unix_tid;
#endif
return thread->unix_pid;
}
/* return the Unix tid to use in ptrace calls for a given thread */
static int get_ptrace_tid( struct thread *thread )
{
if (thread->unix_tid != -1) return thread->unix_tid;
return thread->unix_pid;
}
/* wait for a ptraced child to get a certain signal */
static int wait4_thread( struct thread *thread, int signal )
{
int res, status;
start_watchdog();
for (;;)
{
if ((res = wait4_wrapper( get_ptrace_pid(thread), &status, WUNTRACED, NULL )) == -1)
{
if (errno == EINTR)
{
if (!watchdog_triggered()) continue;
if (debug_level) fprintf( stderr, "%04x: *watchdog* wait4 aborted\n", thread->id );
}
else if (errno == ECHILD) /* must have died */
{
thread->unix_pid = -1;
thread->unix_tid = -1;
}
else perror( "wait4" );
stop_watchdog();
return 0;
}
res = handle_child_status( thread, res, status, signal );
if (!res || res == signal) break;
}
stop_watchdog();
return (thread->unix_pid != -1);
}
/* send a signal to a specific thread */
static inline int tkill( int tgid, int pid, int sig )
{
#ifdef __linux__
int ret = -ENOSYS;
# ifdef __i386__
__asm__( "pushl %%ebx\n\t"
"movl %2,%%ebx\n\t"
"int $0x80\n\t"
"popl %%ebx\n\t"
: "=a" (ret)
: "0" (270) /*SYS_tgkill*/, "r" (tgid), "c" (pid), "d" (sig) );
if (ret == -ENOSYS)
__asm__( "pushl %%ebx\n\t"
"movl %2,%%ebx\n\t"
"int $0x80\n\t"
"popl %%ebx\n\t"
: "=a" (ret)
: "0" (238) /*SYS_tkill*/, "r" (pid), "c" (sig) );
# elif defined(__x86_64__)
__asm__( "syscall" : "=a" (ret)
: "0" (200) /*SYS_tkill*/, "D" (pid), "S" (sig) );
# endif
if (ret >= 0) return ret;
errno = -ret;
return -1;
#elif defined(__FreeBSD__) && defined(HAVE_THR_KILL2)
return thr_kill2( tgid, pid, sig );
#else
errno = ENOSYS;
return -1;
#endif
}
/* initialize the process tracing mechanism */
void init_tracing_mechanism(void)
{
/* no initialization needed for ptrace */
}
/* initialize the per-process tracing mechanism */
void init_process_tracing( struct process *process )
{
/* ptrace setup is done on-demand */
}
/* terminate the per-process tracing mechanism */
void finish_process_tracing( struct process *process )
{
}
/* send a Unix signal to a specific thread */
int send_thread_signal( struct thread *thread, int sig )
{
int ret = -1;
if (thread->unix_pid != -1)
{
if (thread->unix_tid != -1)
{
ret = tkill( thread->unix_pid, thread->unix_tid, sig );
if (ret == -1 && errno == ENOSYS) ret = kill( thread->unix_pid, sig );
}
else ret = kill( thread->unix_pid, sig );
if (ret == -1 && errno == ESRCH) /* thread got killed */
{
thread->unix_pid = -1;
thread->unix_tid = -1;
}
}
if (debug_level && ret != -1)
fprintf( stderr, "%04x: *sent signal* signal=%d\n", thread->id, sig );
return (ret != -1);
}
/* resume a thread after we have used ptrace on it */
static void resume_after_ptrace( struct thread *thread )
{
if (thread->unix_pid == -1) return;
if (ptrace( PTRACE_DETACH, get_ptrace_pid(thread), (caddr_t)1, 0 ) == -1)
{
if (errno == ESRCH) thread->unix_pid = thread->unix_tid = -1; /* thread got killed */
}
}
/* suspend a thread to allow using ptrace on it */
/* you must do a resume_after_ptrace when finished with the thread */
static int suspend_for_ptrace( struct thread *thread )
{
/* can't stop a thread while initialisation is in progress */
if (thread->unix_pid == -1 || !is_process_init_done(thread->process)) goto error;
/* this may fail if the client is already being debugged */
if (ptrace( PTRACE_ATTACH, get_ptrace_pid(thread), 0, 0 ) == -1)
{
if (errno == ESRCH) thread->unix_pid = thread->unix_tid = -1; /* thread got killed */
goto error;
}
if (wait4_thread( thread, SIGSTOP )) return 1;
resume_after_ptrace( thread );
error:
set_error( STATUS_ACCESS_DENIED );
return 0;
}
/* read an int from a thread address space */
static int read_thread_int( struct thread *thread, int *addr, int *data )
{
errno = 0;
*data = ptrace( PTRACE_PEEKDATA, get_ptrace_pid(thread), (caddr_t)addr, 0 );
if ( *data == -1 && errno)
{
file_set_error();
return -1;
}
return 0;
}
/* write an int to a thread address space */
static int write_thread_int( struct thread *thread, int *addr, int data, unsigned int mask )
{
int res;
if (mask != ~0u)
{
if (read_thread_int( thread, addr, &res ) == -1) return -1;
data = (data & mask) | (res & ~mask);
}
if ((res = ptrace( PTRACE_POKEDATA, get_ptrace_pid(thread), (caddr_t)addr, data )) == -1)
file_set_error();
return res;
}
/* return a thread of the process suitable for ptracing */
static struct thread *get_ptrace_thread( struct process *process )
{
struct thread *thread;
LIST_FOR_EACH_ENTRY( thread, &process->thread_list, struct thread, proc_entry )
{
if (thread->unix_pid != -1) return thread;
}
set_error( STATUS_ACCESS_DENIED ); /* process is dead */
return NULL;
}
/* read data from a process memory space */
int read_process_memory( struct process *process, client_ptr_t ptr, data_size_t size, char *dest )
{
struct thread *thread = get_ptrace_thread( process );
unsigned int first_offset, last_offset, len;
int data, *addr;
if (!thread) return 0;
if ((unsigned long)ptr != ptr)
{
set_error( STATUS_ACCESS_DENIED );
return 0;
}
first_offset = ptr % sizeof(int);
last_offset = (size + first_offset) % sizeof(int);
if (!last_offset) last_offset = sizeof(int);
addr = (int *)(unsigned long)(ptr - first_offset);
len = (size + first_offset + sizeof(int) - 1) / sizeof(int);
if (suspend_for_ptrace( thread ))
{
if (len > 1)
{
if (read_thread_int( thread, addr++, &data ) == -1) goto done;
memcpy( dest, (char *)&data + first_offset, sizeof(int) - first_offset );
dest += sizeof(int) - first_offset;
first_offset = 0;
len--;
}
while (len > 1)
{
if (read_thread_int( thread, addr++, &data ) == -1) goto done;
memcpy( dest, &data, sizeof(int) );
dest += sizeof(int);
len--;
}
if (read_thread_int( thread, addr++, &data ) == -1) goto done;
memcpy( dest, (char *)&data + first_offset, last_offset - first_offset );
len--;
done:
resume_after_ptrace( thread );
}
return !len;
}
/* make sure we can write to the whole address range */
/* len is the total size (in ints) */
static int check_process_write_access( struct thread *thread, int *addr, data_size_t len )
{
int page = get_page_size() / sizeof(int);
for (;;)
{
if (write_thread_int( thread, addr, 0, 0 ) == -1) return 0;
if (len <= page) break;
addr += page;
len -= page;
}
return (write_thread_int( thread, addr + len - 1, 0, 0 ) != -1);
}
/* write data to a process memory space */
int write_process_memory( struct process *process, client_ptr_t ptr, data_size_t size, const char *src )
{
struct thread *thread = get_ptrace_thread( process );
int ret = 0, data = 0;
data_size_t len;
int *addr;
unsigned int first_mask, first_offset, last_mask, last_offset;
if (!thread) return 0;
if ((unsigned long)ptr != ptr)
{
set_error( STATUS_ACCESS_DENIED );
return 0;
}
/* compute the mask for the first int */
first_mask = ~0;
first_offset = ptr % sizeof(int);
memset( &first_mask, 0, first_offset );
/* compute the mask for the last int */
last_offset = (size + first_offset) % sizeof(int);
if (!last_offset) last_offset = sizeof(int);
last_mask = 0;
memset( &last_mask, 0xff, last_offset );
addr = (int *)(unsigned long)(ptr - first_offset);
len = (size + first_offset + sizeof(int) - 1) / sizeof(int);
if (suspend_for_ptrace( thread ))
{
if (!check_process_write_access( thread, addr, len ))
{
set_error( STATUS_ACCESS_DENIED );
goto done;
}
/* first word is special */
if (len > 1)
{
memcpy( (char *)&data + first_offset, src, sizeof(int) - first_offset );
src += sizeof(int) - first_offset;
if (write_thread_int( thread, addr++, data, first_mask ) == -1) goto done;
first_offset = 0;
len--;
}
else last_mask &= first_mask;
while (len > 1)
{
memcpy( &data, src, sizeof(int) );
src += sizeof(int);
if (write_thread_int( thread, addr++, data, ~0 ) == -1) goto done;
len--;
}
/* last word is special too */
memcpy( (char *)&data + first_offset, src, last_offset - first_offset );
if (write_thread_int( thread, addr, data, last_mask ) == -1) goto done;
ret = 1;
done:
resume_after_ptrace( thread );
}
return ret;
}
/* retrieve an LDT selector entry */
void get_selector_entry( struct thread *thread, int entry, unsigned int *base,
unsigned int *limit, unsigned char *flags )
{
if (!thread->process->ldt_copy)
{
set_error( STATUS_ACCESS_DENIED );
return;
}
if (entry >= 8192)
{
set_error( STATUS_ACCESS_VIOLATION );
return;
}
if (suspend_for_ptrace( thread ))
{
unsigned char flags_buf[4];
int *addr = (int *)thread->process->ldt_copy + entry;
if (read_thread_int( thread, addr, (int *)base ) == -1) goto done;
if (read_thread_int( thread, addr + 8192, (int *)limit ) == -1) goto done;
addr = (int *)thread->process->ldt_copy + 2*8192 + (entry >> 2);
if (read_thread_int( thread, addr, (int *)flags_buf ) == -1) goto done;
*flags = flags_buf[entry & 3];
done:
resume_after_ptrace( thread );
}
}
#if defined(linux) && (defined(__i386__) || defined(__x86_64__))
#ifdef HAVE_SYS_USER_H
# include <sys/user.h>
#endif
/* debug register offset in struct user */
#define DR_OFFSET(dr) ((((struct user *)0)->u_debugreg) + (dr))
/* retrieve the thread x86 registers */
void get_thread_context( struct thread *thread, CONTEXT *context, unsigned int flags )
{
int i, pid = get_ptrace_tid(thread);
long data[8];
/* all other regs are handled on the client side */
assert( (flags | CONTEXT_i386) == CONTEXT_DEBUG_REGISTERS );
if (!suspend_for_ptrace( thread )) return;
for (i = 0; i < 8; i++)
{
if (i == 4 || i == 5) continue;
errno = 0;
data[i] = ptrace( PTRACE_PEEKUSER, pid, DR_OFFSET(i), 0 );
if ((data[i] == -1) && errno)
{
file_set_error();
goto done;
}
}
context->Dr0 = data[0];
context->Dr1 = data[1];
context->Dr2 = data[2];
context->Dr3 = data[3];
context->Dr6 = data[6];
context->Dr7 = data[7];
context->ContextFlags |= CONTEXT_DEBUG_REGISTERS;
done:
resume_after_ptrace( thread );
}
/* set the thread x86 registers */
void set_thread_context( struct thread *thread, const CONTEXT *context, unsigned int flags )
{
int pid = get_ptrace_tid( thread );
/* all other regs are handled on the client side */
assert( (flags | CONTEXT_i386) == CONTEXT_DEBUG_REGISTERS );
if (!suspend_for_ptrace( thread )) return;
if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(0), context->Dr0 ) == -1) goto error;
if (thread->context) thread->context->Dr0 = context->Dr0;
if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(1), context->Dr1 ) == -1) goto error;
if (thread->context) thread->context->Dr1 = context->Dr1;
if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(2), context->Dr2 ) == -1) goto error;
if (thread->context) thread->context->Dr2 = context->Dr2;
if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(3), context->Dr3 ) == -1) goto error;
if (thread->context) thread->context->Dr3 = context->Dr3;
if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(6), context->Dr6 ) == -1) goto error;
if (thread->context) thread->context->Dr6 = context->Dr6;
if (ptrace( PTRACE_POKEUSER, pid, DR_OFFSET(7), context->Dr7 ) == -1) goto error;
if (thread->context) thread->context->Dr7 = context->Dr7;
resume_after_ptrace( thread );
return;
error:
file_set_error();
resume_after_ptrace( thread );
}
#elif defined(__i386__) && defined(PTRACE_GETDBREGS) && defined(PTRACE_SETDBREGS) && \
(defined(__FreeBSD__) || defined(__FreeBSD_kernel__) || defined(__OpenBSD__) || defined(__NetBSD__))
#include <machine/reg.h>
/* retrieve the thread x86 registers */
void get_thread_context( struct thread *thread, CONTEXT *context, unsigned int flags )
{
int pid = get_ptrace_tid(thread);
struct dbreg dbregs;
/* all other regs are handled on the client side */
assert( (flags | CONTEXT_i386) == CONTEXT_DEBUG_REGISTERS );
if (!suspend_for_ptrace( thread )) return;
if (ptrace( PTRACE_GETDBREGS, pid, (caddr_t) &dbregs, 0 ) == -1) file_set_error();
else
{
#ifdef DBREG_DRX
/* needed for FreeBSD, the structure fields have changed under 5.x */
context->Dr0 = DBREG_DRX((&dbregs), 0);
context->Dr1 = DBREG_DRX((&dbregs), 1);
context->Dr2 = DBREG_DRX((&dbregs), 2);
context->Dr3 = DBREG_DRX((&dbregs), 3);
context->Dr6 = DBREG_DRX((&dbregs), 6);
context->Dr7 = DBREG_DRX((&dbregs), 7);
#else
context->Dr0 = dbregs.dr0;
context->Dr1 = dbregs.dr1;
context->Dr2 = dbregs.dr2;
context->Dr3 = dbregs.dr3;
context->Dr6 = dbregs.dr6;
context->Dr7 = dbregs.dr7;
#endif
context->ContextFlags |= CONTEXT_DEBUG_REGISTERS;
}
resume_after_ptrace( thread );
}
/* set the thread x86 registers */
void set_thread_context( struct thread *thread, const CONTEXT *context, unsigned int flags )
{
int pid = get_ptrace_tid(thread);
struct dbreg dbregs;
/* all other regs are handled on the client side */
assert( (flags | CONTEXT_i386) == CONTEXT_DEBUG_REGISTERS );
if (!suspend_for_ptrace( thread )) return;
#ifdef DBREG_DRX
/* needed for FreeBSD, the structure fields have changed under 5.x */
DBREG_DRX((&dbregs), 0) = context->Dr0;
DBREG_DRX((&dbregs), 1) = context->Dr1;
DBREG_DRX((&dbregs), 2) = context->Dr2;
DBREG_DRX((&dbregs), 3) = context->Dr3;
DBREG_DRX((&dbregs), 4) = 0;
DBREG_DRX((&dbregs), 5) = 0;
DBREG_DRX((&dbregs), 6) = context->Dr6;
DBREG_DRX((&dbregs), 7) = context->Dr7;
#else
dbregs.dr0 = context->Dr0;
dbregs.dr1 = context->Dr1;
dbregs.dr2 = context->Dr2;
dbregs.dr3 = context->Dr3;
dbregs.dr4 = 0;
dbregs.dr5 = 0;
dbregs.dr6 = context->Dr6;
dbregs.dr7 = context->Dr7;
#endif
if (ptrace( PTRACE_SETDBREGS, pid, (caddr_t) &dbregs, 0 ) == -1) file_set_error();
else if (thread->context) /* update the cached values */
{
thread->context->Dr0 = context->Dr0;
thread->context->Dr1 = context->Dr1;
thread->context->Dr2 = context->Dr2;
thread->context->Dr3 = context->Dr3;
thread->context->Dr6 = context->Dr6;
thread->context->Dr7 = context->Dr7;
}
resume_after_ptrace( thread );
}
#else /* linux || __FreeBSD__ */
/* retrieve the thread x86 registers */
void get_thread_context( struct thread *thread, CONTEXT *context, unsigned int flags )
{
}
/* set the thread x86 debug registers */
void set_thread_context( struct thread *thread, const CONTEXT *context, unsigned int flags )
{
}
#endif /* linux || __FreeBSD__ */
#endif /* USE_PTRACE */
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