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Tweak disable_debugger_attachment a little

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Don't warn when we have no implementation of this function (since it's
on-by-default); reformat the changes entry; fix an overlong line.
This commit is contained in:
Nick Mathewson 2011-11-24 23:39:44 -05:00
parent 68114ca52c
commit 3508de3cd6
2 changed files with 32 additions and 22 deletions
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24
changes/disable_debugger_attachment
View File

@ -1,14 +1,16 @@
o Minor features:
- If set to 1, Tor will attempt to prevent basic debugging attachment
attempts by other processes. It has no impact for users who wish to
attach if they have CAP_SYS_PTRACE or if they are root. We believe that
this feature works on modern Gnu/Linux distributions, and that it may
also work on *BSD systems (untested). Some modern Gnu/Linux systems such
as Ubuntu have the kernel.yama.ptrace_scope sysctl and by default enable
it as an attempt to limit the PTRACE scope for all user processes by
default. This feature will attempt to limit the PTRACE scope for Tor
specifically - it will not attempt to alter the system wide ptrace scope
as it may not even exist. If you wish to attach to Tor with a debugger
such as gdb or strace you will want to set this to 0 for the duration of
- If set to 1, Tor will attempt to prevent basic debugging
attachment attempts by other processes. It has no impact for
users who wish to attach if they have CAP_SYS_PTRACE or if they
are root. We believe that this feature works on modern
Gnu/Linux distributions, and that it may also work on OSX and
some *BSD systems (untested). Some modern Gnu/Linux systems
such as Ubuntu have the kernel.yama.ptrace_scope sysctl and by
default enable it as an attempt to limit the PTRACE scope for
all user processes by default. This feature will attempt to
limit the PTRACE scope for Tor specifically - it will not
attempt to alter the system wide ptrace scope as it may not even
exist. If you wish to attach to Tor with a debugger such as gdb
or strace you will want to set this to 0 for the duration of
your debugging. Normal users should leave it on. (Default: 1)

28
src/or/config.c
View File

@ -40,11 +40,6 @@
#include <shlobj.h>
#endif
#include "procmon.h"
/* From main.c */
extern int quiet_level;
/* Includes for the process attaching prevention */
#if defined(HAVE_SYS_PRCTL_H) && defined(__linux__)
#include <sys/prctl.h>
@ -53,6 +48,11 @@ extern int quiet_level;
#include <sys/ptrace.h>
#endif
#include "procmon.h"
/* From main.c */
extern int quiet_level;
/** Enumeration of types which option values can take */
typedef enum config_type_t {
CONFIG_TYPE_STRING = 0, /**< An arbitrary string. */
@ -703,25 +703,33 @@ get_dirportfrontpage(void)
* attach to the Tor process.
*/
/** Attempt to disable debugger attachment. */
static int tor_disable_debugger_attach(void) {
int r;
static int
tor_disable_debugger_attach(void)
{
int r, attempted;
r = -1;
attempted = 0;
log_debug(LD_CONFIG,
"Attemping to disable debugger attachment to Tor for unprivileged users.");
"Attemping to disable debugger attachment to Tor for "
"unprivileged users.");
#if defined(__linux__) && defined(HAVE_SYS_PRCTL_H) && defined(HAVE_PRCTL)
#ifdef PR_SET_DUMPABLE
attempted = 1;
r = prctl(PR_SET_DUMPABLE, 0);
#endif
#endif
#if defined(__APPLE__) && defined(PT_DENY_ATTACH)
r = ptrace(PT_DENY_ATTACH, 0, 0, 0);
if (r < 0) {
attempted = 1;
r = ptrace(PT_DENY_ATTACH, 0, 0, 0);
}
#endif
// XXX: TODO - Mac OS X has dtrace and this may be disabled - implement it here
// XXX: TODO - Windows probably has something similar - implement it here
if (r == 0) {
log_debug(LD_CONFIG,"Debugger attachment disabled for unprivileged users.");
} else {
} else if (attempted) {
log_warn(LD_CONFIG, "Unable to disable ptrace attach: %s",
strerror(errno));
}