linux-stable.git/include/linux/ptrace.h, branch v3.3.6

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/audit

2012-01-18T00:41:31+00:00

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/audit: (29 commits)
  audit: no leading space in audit_log_d_path prefix
  audit: treat s_id as an untrusted string
  audit: fix signedness bug in audit_log_execve_info()
  audit: comparison on interprocess fields
  audit: implement all object interfield comparisons
  audit: allow interfield comparison between gid and ogid
  audit: complex interfield comparison helper
  audit: allow interfield comparison in audit rules
  Kernel: Audit Support For The ARM Platform
  audit: do not call audit_getname on error
  audit: only allow tasks to set their loginuid if it is -1
  audit: remove task argument to audit_set_loginuid
  audit: allow audit matching on inode gid
  audit: allow matching on obj_uid
  audit: remove audit_finish_fork as it can't be called
  audit: reject entry,always rules
  audit: inline audit_free to simplify the look of generic code
  audit: drop audit_set_macxattr as it doesn't do anything
  audit: inline checks for not needing to collect aux records
  audit: drop some potentially inadvisable likely notations
  ...

Use evil merge to fix up grammar mistakes in Kconfig file.

Bad speling and horrible grammar (and copious swearing) is to be
expected, but let's keep it to commit messages and comments, rather than
expose it to users in config help texts or printouts.

Audit: push audit success and retcode into arch ptrace.h

2012-01-17T21:16:56+00:00

The audit system previously expected arches calling to audit_syscall_exit to
supply as arguments if the syscall was a success and what the return code was.
Audit also provides a helper AUDITSC_RESULT which was supposed to simplify things
by converting from negative retcodes to an audit internal magic value stating
success or failure.  This helper was wrong and could indicate that a valid
pointer returned to userspace was a failed syscall.  The fix is to fix the
layering foolishness.  We now pass audit_syscall_exit a struct pt_reg and it
in turns calls back into arch code to collect the return value and to
determine if the syscall was a success or failure.  We also define a generic
is_syscall_success() macro which determines success/failure based on if the
value is < -MAX_ERRNO.  This works for arches like x86 which do not use a
separate mechanism to indicate syscall failure.

We make both the is_syscall_success() and regs_return_value() static inlines
instead of macros.  The reason is because the audit function must take a void*
for the regs.  (uml calls theirs struct uml_pt_regs instead of just struct
pt_regs so audit_syscall_exit can't take a struct pt_regs).  Since the audit
function takes a void* we need to use static inlines to cast it back to the
arch correct structure to dereference it.

The other major change is that on some arches, like ia64, MIPS and ppc, we
change regs_return_value() to give us the negative value on syscall failure.
THE only other user of this macro, kretprobe_example.c, won't notice and it
makes the value signed consistently for the audit functions across all archs.

In arch/sh/kernel/ptrace_64.c I see that we were using regs[9] in the old
audit code as the return value.  But the ptrace_64.h code defined the macro
regs_return_value() as regs[3].  I have no idea which one is correct, but this
patch now uses the regs_return_value() function, so it now uses regs[3].

For powerpc we previously used regs->result but now use the
regs_return_value() function which uses regs->gprs[3].  regs->gprs[3] is
always positive so the regs_return_value(), much like ia64 makes it negative
before calling the audit code when appropriate.

Signed-off-by: Eric Paris 
Acked-by: H. Peter Anvin  [for x86 portion]
Acked-by: Tony Luck  [for ia64]
Acked-by: Richard Weinberger  [for uml]
Acked-by: David S. Miller  [for sparc]
Acked-by: Ralf Baechle  [for mips]
Acked-by: Benjamin Herrenschmidt  [for ppc]

ptrace: do not audit capability check when outputing /proc/pid/stat

2012-01-05T23:53:00+00:00

Reading /proc/pid/stat of another process checks if one has ptrace permissions
on that process.  If one does have permissions it outputs some data about the
process which might have security and attack implications.  If the current
task does not have ptrace permissions the read still works, but those fields
are filled with inocuous (0) values.  Since this check and a subsequent denial
is not a violation of the security policy we should not audit such denials.

This can be quite useful to removing ptrace broadly across a system without
flooding the logs when ps is run or something which harmlessly walks proc.

Signed-off-by: Eric Paris 
Acked-by: Serge E. Hallyn

ptrace: dont send SIGSTOP on auto-attach if PT_SEIZED

2011-07-17T18:23:52+00:00

The fake SIGSTOP during attach has numerous problems. PTRACE_SEIZE
is already fine, but we have basically the same problems is SIGSTOP
is sent on auto-attach, the tracer can't know if this signal signal
should be cancelled or not.

Change ptrace_event() to set JOBCTL_TRAP_STOP if the new child is
PT_SEIZED, this triggers the PTRACE_EVENT_STOP report.

Thereafter a PT_SEIZED task can never report the bogus SIGSTOP.

Test-case:

	#define PTRACE_SEIZE		0x4206
	#define PTRACE_SEIZE_DEVEL	0x80000000
	#define PTRACE_EVENT_STOP	7
	#define WEVENT(s)		((s & 0xFF0000) >> 16)

	int main(void)
	{
		int child, grand_child, status;
		long message;

		child = fork();
		if (!child) {
			kill(getpid(), SIGSTOP);
			fork();
			assert(0);
			return 0x23;
		}

		assert(ptrace(PTRACE_SEIZE, child, 0,PTRACE_SEIZE_DEVEL) == 0);
		assert(wait(&status) == child);
		assert(WIFSTOPPED(status) && WSTOPSIG(status) == SIGSTOP);

		assert(ptrace(PTRACE_SETOPTIONS, child, 0, PTRACE_O_TRACEFORK) == 0);

		assert(ptrace(PTRACE_CONT, child, 0,0) == 0);
		assert(waitpid(child, &status, 0) == child);
		assert(WIFSTOPPED(status) && WSTOPSIG(status) == SIGTRAP);
		assert(WEVENT(status) == PTRACE_EVENT_FORK);

		assert(ptrace(PTRACE_GETEVENTMSG, child, 0, &message) == 0);
		grand_child = message;

		assert(waitpid(grand_child, &status, 0) == grand_child);
		assert(WIFSTOPPED(status) && WSTOPSIG(status) == SIGTRAP);
		assert(WEVENT(status) == PTRACE_EVENT_STOP);

		kill(child, SIGKILL);
		kill(grand_child, SIGKILL);
		return 0;
	}

Signed-off-by: Oleg Nesterov 
Acked-by: Tejun Heo

ptrace: mv send-SIGSTOP from do_fork() to ptrace_init_task()

2011-07-17T18:23:51+00:00

If the new child is traced, do_fork() adds the pending SIGSTOP.
It assumes that either it is traced because of auto-attach or the
tracer attached later, in both cases sigaddset/set_thread_flag is
correct even if SIGSTOP is already pending.

Now that we have PTRACE_SEIZE this is no longer right in the latter
case. If the tracer does PTRACE_SEIZE after copy_process() makes the
child visible the queued SIGSTOP is wrong.

We could check PT_SEIZED bit and change ptrace_attach() to set both
PT_PTRACED and PT_SEIZED bits simultaneously but see the next patch,
we need to know whether this child was auto-attached or not anyway.

So this patch simply moves this code to ptrace_init_task(), this
way we can never race with ptrace_attach().

Signed-off-by: Oleg Nesterov 
Acked-by: Tejun Heo

ptrace_init_task: initialize child->jobctl explicitly

2011-07-17T18:23:51+00:00

new_child->jobctl is not initialized during the fork, it is copied
from parent->jobctl. Currently this is harmless, the forking task
is running and copy_process() can't succeed if signal_pending() is
true, so only JOBCTL_STOP_DEQUEUED can be copied. Still this is a
bit fragile, it would be more clean to set ->jobctl = 0 explicitly.

Also, check ->ptrace != 0 instead of PT_PTRACED, move the
CONFIG_HAVE_HW_BREAKPOINT code up.

Signed-off-by: Oleg Nesterov 
Acked-by: Tejun Heo

ptrace: ptrace_reparented() should check same_thread_group()

2011-06-27T18:30:10+00:00

ptrace_reparented() naively does parent != real_parent, this means
it returns true even if the tracer _is_ the real parent. This is per
process thing, not per-thread. The only reason ->real_parent can
point to the non-leader thread is that we have __WNOTHREAD.

Change it to check !same_thread_group(parent, real_parent).

It has two callers, and in both cases the current check does not
look right.

exit_notify: we should respect ->exit_signal if the exiting leader
is traced by any thread from the parent thread group. It is the
child of the whole group, and we are going to send the signal to
the whole group.

wait_task_zombie: without __WNOTHREAD do_wait() should do the same
for any thread, only sys_ptrace() is "bound" to the single thread.
However do_wait(WEXITED) succeeds but does not release a traced
natural child unless the caller is the tracer.

Test-case:

	void *tfunc(void *arg)
	{
		assert(ptrace(PTRACE_ATTACH, (long)arg, 0,0) == 0);
		pause();
		return NULL;
	}

	int main(void)
	{
		pthread_t thr;
		pid_t pid, stat, ret;

		pid = fork();
		if (!pid) {
			pause();
			assert(0);
		}

		assert(pthread_create(&thr, NULL, tfunc, (void*)(long)pid) == 0);

		assert(waitpid(-1, &stat, 0) == pid);
		assert(WIFSTOPPED(stat));

		kill(pid, SIGKILL);

		assert(waitpid(-1, &stat, 0) == pid);
		assert(WIFSIGNALED(stat) && WTERMSIG(stat) == SIGKILL);

		ret = waitpid(pid, &stat, 0);
		if (ret < 0)
			return 0;

		printf("WTF? %d is dead, but: wait=%d stat=%x\n",
				pid, ret, stat);

		return 1;
	}

Note that the main thread simply does

	pid = fork();
	kill(pid, SIGKILL);

and then without the patch wait4(WEXITED) succeeds twice and reports
WTERMSIG(stat) == SIGKILL.

Signed-off-by: Oleg Nesterov 
Acked-by: Tejun Heo

ptrace: s/tracehook_tracer_task()/ptrace_parent()/

2011-06-22T17:26:29+00:00

tracehook.h is on the way out.  Rename tracehook_tracer_task() to
ptrace_parent() and move it from tracehook.h to ptrace.h.

Signed-off-by: Tejun Heo 
Cc: Christoph Hellwig 
Cc: John Johansen 
Cc: Stephen Smalley 
Signed-off-by: Oleg Nesterov

ptrace: move SIGTRAP on exec(2) logic to ptrace_event()

2011-06-22T17:26:28+00:00

Move SIGTRAP on exec(2) logic from tracehook_report_exec() to
ptrace_event().  This is part of changes to make ptrace_event()
smarter and handle ptrace event related details in one place.

This doesn't introduce any behavior change.

Signed-off-by: Tejun Heo 
Signed-off-by: Oleg Nesterov

ptrace: introduce ptrace_event_enabled() and simplify ptrace_event() and tracehook_prepare_clone()

2011-06-22T17:26:28+00:00

This patch implements ptrace_event_enabled() which tests whether a
given PTRACE_EVENT_* is enabled and use it to simplify ptrace_event()
and tracehook_prepare_clone().

PT_EVENT_FLAG() macro is added which calculates PT_TRACE_* flag from
PTRACE_EVENT_*.  This is used to define PT_TRACE_* flags and by
ptrace_event_enabled() to find the matching flag.

This is used to make ptrace_event() and tracehook_prepare_clone()
simpler.

* ptrace_event() callers were responsible for providing mask to test
  whether the event was enabled.  This patch implements
  ptrace_event_enabled() and make ptrace_event() drop @mask and
  determine whether the event is enabled from @event.  Note that
  @event is constant and this conversion doesn't add runtime overhead.

  All conversions except tracehook_report_clone_complete() are
  trivial.  tracehook_report_clone_complete() used to use 0 for @mask
  (always enabled) but now tests whether the specified event is
  enabled.  This doesn't cause any behavior difference as it's
  guaranteed that the event specified by @trace is enabled.

* tracehook_prepare_clone() now only determines which event is
  applicable and use ptrace_event_enabled() for enable test.

This doesn't introduce any behavior change.

Signed-off-by: Tejun Heo 
Signed-off-by: Oleg Nesterov