Mac: Tell the GPU sandbox to deny a few things.

chrome/browser/gpu.sb

Index: chrome/browser/gpu.sb
diff --git a/chrome/browser/gpu.sb b/chrome/browser/gpu.sb
index ce5b2d2f727472959c692847b43dd0bf945472a0..9cd27b829f2a4c5346160e424c3eb463ebc8df08 100644
--- a/chrome/browser/gpu.sb
+++ b/chrome/browser/gpu.sb
@@ -6,5 +6,14 @@
 
 ; *** The contents of chrome/common/common.sb are implicitly included here. ***
 
-; TODO(thakis): Deny most things by default.
-(allow default)
+; The GPU process opens a shared memory file to communicate with the renderer.
+; This is backed by a file in /var/folders.
+(allow file-read* file-write* (regex "^/(private/)?(tmp|var)(/|$)"))

[jeremy, 2010/12/03 14:22:09]

I'm a bit apprehensive about opening this since this will allow access to any
file in /tmp or /var.

Would it be possible to have the browser be the one to allocate the shared
memory file and send the handle back to the GPU process?  The OS is smart enough
to allow file access in the Sandbox to FDs sent over IPC.

(sidenote, you should only need /private/tmp here and not /tmp since the sandbox
operates on normalized paths and /tmp is just a symlink).

[Nico, 2010/12/04 00:26:10]

Worth thinking about…I've filed a bug and put in a TODO.
Done.

[Nico, 2010/12/04 01:58:36]

Turns out that the ringbuffer creation fails if I replace (private/)? with
private/, so I undid this change.

+
+; Without this, the GPU process prints
+; *** CFMessagePort: bootstrap_register(): failed 268435459 (0x10000003) '(ipc/send) invalid destination port', port = 0x5907, name = 'com.apple.tsm.portname'
+; That's probably harmless, but allowing the look-up is also probably harmless.

[jeremy, 2010/12/03 14:22:09]

I don't think you need this comment.  Perhaps something like:
Allow communication between the GPU process and UI server.

Another piece of useful information would be the system call that needs this.

[Nico, 2010/12/04 00:26:10]

Done.
It's this stack:


*** Sandbox Exception: pid: 17186
	0   Chromium Framework                  0x00d20d10
base::debug::StackTrace::StackTrace() + 32
	1   Chromium Framework                  0x001a8cc4 (anonymous
namespace)::SandboxBlockedExceptionHandler(int) + 69
	2   libSystem.B.dylib                   0x93ac01fb _sigtramp + 43
	3   ???                                 0xffffffff 0x0 + 4294967295
	4   libSystem.B.dylib                   0x93a719f1 vproc_mig_look_up2 + 229
	5   libSystem.B.dylib                   0x93a717cc bootstrap_look_up2 + 294
	6   libSystem.B.dylib                   0x93a716a4 bootstrap_look_up + 55
	7   libSystem.B.dylib                   0x93b699b2 _asl_get_global_server_port
+ 88
	8   libSystem.B.dylib                   0x93ab6bfd asl_open + 73
	9   CoreFoundation                      0x99753074 __CFLogCString + 116
	10  CoreFoundation                      0x99752fee _CFLogvEx + 334
	11  CoreFoundation                      0x9975ea6a CFLog + 58
	12  CoreFoundation                      0x996e67c5 __CFMessagePortCreateLocal +
1765
	13  HIToolbox                           0x977f2015
InitializeTSMMessageReceiving + 137
	14  HIToolbox                           0x977f1e49 InitTSMFirstEventTime + 180
	15  HIToolbox                           0x977f1461 _FirstEventTime + 1204
	16  HIToolbox                           0x977f0e44 RunCurrentEventLoopInMode +
48
	17  HIToolbox                           0x977f0c8d ReceiveNextEventCommon + 158
	18  HIToolbox                           0x977f0bd6
BlockUntilNextEventMatchingListInMode + 81
	19  AppKit                              0x98bdda89 _DPSNextEvent + 847
	20  AppKit                              0x98bdd2ca -[NSApplication
nextEventMatchingMask:untilDate:inMode:dequeue:] + 156
	21  AppKit                              0x98b9f55b -[NSApplication run] + 821
	22  Chromium Framework                  0x00d08004
base::MessagePumpNSApplication::DoRun(base::MessagePump::Delegate*) + 130
	23  Chromium Framework                  0x00d085f3
base::MessagePumpCFRunLoopBase::Run(base::MessagePump::Delegate*) + 175
	24  Chromium Framework                  0x00d3fa79 MessageLoop::RunInternal() +
209
	25  Chromium Framework                  0x00d3fa93 MessageLoop::RunHandler() +
17
	26  Chromium Framework                  0x00d3faf7 MessageLoop::Run() + 35
	27  Chromium Framework                  0x00b88984 GpuMain(MainFunctionParams
const&) + 1556
	28  Chromium Framework                  0x00008c36 (anonymous
namespace)::RunNamedProcessTypeMain(std::string const&, MainFunctionParams
const&) + 78
	29  Chromium Framework                  0x000088d6 ChromeMain + 3496
	30  Chromium Helper                     0x00001f52 main + 24
	31  Chromium Helper                     0x00001f0e start + 54
2010-12-03 21:14:16.383 Chromium Helper[17186:107] *** CFMessagePort:
bootstrap_register(): failed 268435459 (0x10000003) '(ipc/send) invalid
destination port', port = 0x5907, name = 'com.apple.tsm.portname'
See /usr/include/servers/bootstrap_defs.h for the error codes.
(happens only in Debug)

I don't think including any one of the function names in this stack really
helps.

[jeremy, 2010/12/05 08:04:50]

Are you sure you need this?  Does this cause things to not work, or just print a
warning?

Apologies for pressing the point, just wanted to make sure this is as minimal as
possible.

+(allow mach-lookup (global-name "com.apple.tsm.uiserver"))
+
+; From renderer.sb

[jeremy, 2010/12/03 14:22:09]

Could you change this comment to the system call that needs this.  I'm also fine
with removing the comment since this is pretty harmless.

[Nico, 2010/12/04 00:26:10]

Done, removed the comment.

+(allow file-read-metadata (literal "/"))