ConvertStringSecurityDescriptorToSecurityDescriptor() is used when
creating the initial connection pipe. Because this is done from inside
DllMain(), we cannot use advapi32 (where this function is). Instead,
save the binary representation of the self-relative SECURITY_DESCRIPTOR.
It is conceivable that this could change, but unlikely as this is the
same blob that would be stored on a file in NTFS.
Another potential approach would be to not make the pipe available to
all integrity levels here, and instead modify the Chromium sandbox code
to allow a specific pipe name prefix that would have to correspond with
the pipe name that Crashpad creates.
Similarly, UuidCreate() (used when initializing the database) is in a
DLL that can't be loaded early, so use the Linux/Android implementation
on Windows too.
R=mark@chromium.org
BUG=chromium:655788,chromium:656800
Change-Id: I434f8e96fc275fc30d0a31208b025bfc08595ff9
Reviewed-on: https://chromium-review.googlesource.com/417223
Reviewed-by: Mark Mentovai <mark@chromium.org>
Second follow up to https://chromium-review.googlesource.com/c/400015/
The ideal would be that if we fail to start the handler, then we don't
end up passing through our unhandled exception filter at all.
In the case of the non-initial client (i.e. renderers) we can do this by
not setting our UnhandledExceptionFilter until after we know we've
connected successfully (because those connections are synchronous from
its point of view). We also change WaitForNamedPipe in the connection
message to block forever, so as long as the precreated pipe exists,
they'll wait to connect. After the initial client has passed the server
side of that pipe to the handler, the handler has the only handle to it.
So, if the handler has disappeared for whatever reason, pipe-connecting
clients will fail with FILE_NOT_FOUND, and will not stick around in the
connection loop. This means non-initial clients do not need additional
logic to avoid getting stuck in our UnhandledExceptionFilter.
For the initial client, it would be ideal to avoid passing through our
UEF too, but none of the 3 options are great:
1. Block until we find out if we started, and then install the filter.
We don't want to do that, because we don't want to wait.
2. Restore the old filter if it turns out we failed to start. We can't
do that because Chrome disables ::SetUnhandledExceptionFilter()
immediately after StartHandler/SetHandlerIPCPipe returns.
3. Don't install our filter until we've successfully started. We don't
want to do that because we'd miss early crashes, negating the benefit
of deferred startup.
So, we do need to pass through our UnhandledExceptionFilter. I don't
want more Win32 API calls during the vulnerable filter function. So, at
any point during async startup where there's a failure, set a global
atomic that allows the filter function to abort without trying to signal
a handler that's known to not exist.
One further improvement we might want to look at is unexpected
termination of the handler (as opposed to a failure to start) which
would still result in a useless Sleep(60s). This isn't new behaviour,
but now we have a clear thing to do if we detect the handler is gone.
(Also a missing DWORD/size_t cast for the _x64 bots.)
R=mark@chromium.org
BUG=chromium:567850,chromium:656800
Change-Id: I5be831ca39bd8b2e5c962b9647c8bd469e2be878
Reviewed-on: https://chromium-review.googlesource.com/400985
Reviewed-by: Mark Mentovai <mark@chromium.org>
Previously, StartHandler() launched the handler process, then connected
over a pipe to register for crash handling. Instead, the initial client
can create and inherit handles to the handler and pass those handle
values and other data (addresses, etc.) on the command line.
This should improve startup time as there's no need to synchronize with
the process at startup, and allows avoiding a call to CreateProcess()
directly in StartHandler(), which is important for registration for
crash reporting from DllMain().
Incidentally adds new utility functions for string/number conversion and
string splitting.
Note: API change; UseHandler() is removed for all platforms.
BUG=chromium:567850,chromium:656800
Change-Id: I1602724183cb107f805f109674c53e95841b24fd
Reviewed-on: https://chromium-review.googlesource.com/400015
Reviewed-by: Mark Mentovai <mark@chromium.org>
This consolidates all of the twisted casts and comments that discuss how
HANDLEs are really only 32 bits wide even in 64-bit processes on 64-bit
operating systems into a single location.
R=scottmg@chromium.org
Review URL: https://codereview.chromium.org/1422503015 .
I thought I had confirmed that this still allocated and ignored the flag
on older OSs, but I must have not had the PLOG active yet? I'm not sure
what I did. (I might try to blame VMware as it has an annoying habit of
caching old binaries when you use it's "Shared Folders" feature to point
at the dev machine's build dir.)
I confirmed that it does work on Win8 and Win10 but doesn't on Win XP
and Win 7.
R=mark@chromium.org
BUG=crashpad:52
Review URL: https://codereview.chromium.org/1405243002 .
Capture the memory for the loader lock (can be inspected by !cs), as
well as all locks that were created with .DebugInfo which can be viewed
with !locks.
e.g.
0:000> !cs ntdll!LdrpLoaderLock
-----------------------------------------
Critical section = 0x778d6410 (ntdll!LdrpLoaderLock+0x0)
DebugInfo = 0x778d6b6c
NOT LOCKED
LockSemaphore = 0x0
SpinCount = 0x04000000
0:000> !locks -v
CritSec ntdll!RtlpProcessHeapsListLock+0 at 778d7620
LockCount NOT LOCKED
RecursionCount 0
OwningThread 0
EntryCount 0
ContentionCount 0
CritSec +7a0248 at 007a0248
LockCount NOT LOCKED
RecursionCount 0
OwningThread 0
EntryCount 0
ContentionCount 0
CritSec crashy_program!g_critical_section_with_debug_info+0 at 01342c48
LockCount NOT LOCKED
RecursionCount 0
OwningThread 0
EntryCount 0
ContentionCount 0
CritSec crashy_program!crashpad::`anonymous namespace'::g_test_critical_section+0 at 01342be0
WaiterWoken No
LockCount 0
RecursionCount 1
OwningThread 34b8
EntryCount 0
ContentionCount 0
*** Locked
Scanned 4 critical sections
R=mark@chromium.org
BUG=crashpad:52
Review URL: https://codereview.chromium.org/1392093003 .
Windows requires the connection to the handler to do anything, so it
can't really be implemented or tested without CrashpadClient and the
connection machinery.
R=mark@chromium.org
BUG=crashpad:53
Review URL: https://codereview.chromium.org/1356383002 .
This replaces the registration server, and adds dispatch to a delegate
on crash requests.
(As you are already aware) we went around in circles on trying to come
up with a slightly-too-fancy threading design. All of them seemed to
have problems when it comes to out of order events, and orderly
shutdown, so I've gone back to something not-too-fancy.
Two named pipe instances (that clients connect to) are created. These
are used only for registration (which should take <1ms), so 2 should be
sufficient to avoid any waits. When a client registers, we duplicate
an event to it, which is used to signal when it wants a dump taken.
The server registers threadpool waits on that event, and also on the
process handle (which will be signalled when the client process exits).
These requests (in particular the taking of the dump) are serviced
on the threadpool, which avoids us needing to manage those threads,
but still allows parallelism in taking dumps. On process termination,
we use an IO Completion Port to post a message back to the main thread
to request cleanup. This complexity is necessary so that we can
unregister the threadpool waits without being on the threadpool, which
we need to do synchronously so that we can be sure that no further
callbacks will execute (and expect to have the client data around
still).
In a followup, I will readd support for DumpWithoutCrashing -- I don't
think it will be too difficult now that we have an orderly way to
clean up client records in the server.
R=cpu@chromium.org, mark@chromium.org, jschuh@chromium.org
BUG=crashpad:1,crashpad:45
Review URL: https://codereview.chromium.org/1301853002 .
