[PATCH] server: Allow skipping debug handle retrieval in get_process_debug_info.
Today, Wine uses NtQueryInformationProcess/ProcessDebugPort to detect whether the current process is being debugged. If it is, the process issues a breakpoint to yield control to the debugger. Some debuggers (e.g. latest CDB) appear to create debug handles with restricted DACL, which causes querying debug port to fail with STATUS_ACCESS_DENIED. This results in the debuggee erroneously skipping the initial breakpoint. Fix this by making retrieval of debug port object handle optional. Also, skip debug port object handle retrieval if serving requests that don't need it (i.e. ProcessDebugPort and ProcessDebugFlags). This also eliminates the extra round trip to the server for closing the unneeded debug port object handle. Signed-off-by: Jinoh Kang <jinoh.kang.kr(a)gmail.com> --- dlls/ntdll/unix/process.c | 13 ++++--------- include/wine/server_protocol.h | 4 +++- server/process.c | 2 +- server/protocol.def | 1 + server/request.h | 3 ++- server/trace.c | 1 + 6 files changed, 12 insertions(+), 12 deletions(-) diff --git a/dlls/ntdll/unix/process.c b/dlls/ntdll/unix/process.c index c834ef85c79..dfe040eeb25 100644 --- a/dlls/ntdll/unix/process.c +++ b/dlls/ntdll/unix/process.c @@ -1259,19 +1259,16 @@ NTSTATUS WINAPI NtQueryInformationProcess( HANDLE handle, PROCESSINFOCLASS class if (!info) ret = STATUS_ACCESS_VIOLATION; else { - HANDLE debug; - SERVER_START_REQ(get_process_debug_info) { req->handle = wine_server_obj_handle( handle ); + req->want_debug_obj = 0; ret = wine_server_call( req ); - debug = wine_server_ptr_handle( reply->debug ); } SERVER_END_REQ; if (ret == STATUS_SUCCESS) { *(DWORD_PTR *)info = ~0ul; - NtClose( debug ); } else if (ret == STATUS_PORT_NOT_SET) { @@ -1290,18 +1287,15 @@ NTSTATUS WINAPI NtQueryInformationProcess( HANDLE handle, PROCESSINFOCLASS class if (!info) ret = STATUS_ACCESS_VIOLATION; else { - HANDLE debug; - SERVER_START_REQ(get_process_debug_info) { req->handle = wine_server_obj_handle( handle ); + req->want_debug_obj = 0; ret = wine_server_call( req ); - debug = wine_server_ptr_handle( reply->debug ); *(DWORD *)info = reply->debug_children; } SERVER_END_REQ; - if (ret == STATUS_SUCCESS) NtClose( debug ); - else if (ret == STATUS_PORT_NOT_SET) ret = STATUS_SUCCESS; + if (ret == STATUS_PORT_NOT_SET) ret = STATUS_SUCCESS; } } else ret = STATUS_INFO_LENGTH_MISMATCH; @@ -1323,6 +1317,7 @@ NTSTATUS WINAPI NtQueryInformationProcess( HANDLE handle, PROCESSINFOCLASS class SERVER_START_REQ(get_process_debug_info) { req->handle = wine_server_obj_handle( handle ); + req->want_debug_obj = 1; ret = wine_server_call( req ); *(HANDLE *)info = wine_server_ptr_handle( reply->debug ); } diff --git a/include/wine/server_protocol.h b/include/wine/server_protocol.h index b37a8e8e056..eb880b98f46 100644 --- a/include/wine/server_protocol.h +++ b/include/wine/server_protocol.h @@ -1018,6 +1018,8 @@ struct get_process_debug_info_request { struct request_header __header; obj_handle_t handle; + int want_debug_obj; + char __pad_20[4]; }; struct get_process_debug_info_reply { @@ -6279,7 +6281,7 @@ union generic_reply /* ### protocol_version begin ### */ -#define SERVER_PROTOCOL_VERSION 737 +#define SERVER_PROTOCOL_VERSION 738 /* ### protocol_version end ### */ diff --git a/server/process.c b/server/process.c index 6d794ba5ead..635ab9b6450 100644 --- a/server/process.c +++ b/server/process.c @@ -1528,7 +1528,7 @@ DECL_HANDLER(get_process_debug_info) reply->debug_children = process->debug_children; if (!process->debug_obj) set_error( STATUS_PORT_NOT_SET ); - else reply->debug = alloc_handle( current->process, process->debug_obj, DEBUG_ALL_ACCESS, 0 ); + else if (req->want_debug_obj) reply->debug = alloc_handle( current->process, process->debug_obj, DEBUG_ALL_ACCESS, 0 ); release_object( process ); } diff --git a/server/protocol.def b/server/protocol.def index c83e6a2ef7c..1e73e2783f8 100644 --- a/server/protocol.def +++ b/server/protocol.def @@ -968,6 +968,7 @@ typedef struct /* Retrieve debug information about a process */ @REQ(get_process_debug_info) obj_handle_t handle; /* process handle */ + int want_debug_obj; /* want debug port object? */ @REPLY obj_handle_t debug; /* handle to debug port */ int debug_children; /* inherit debugger to child processes */ diff --git a/server/request.h b/server/request.h index 6a63e842357..95473ae762f 100644 --- a/server/request.h +++ b/server/request.h @@ -789,7 +789,8 @@ C_ASSERT( FIELD_OFFSET(struct get_process_info_reply, priority) == 56 ); C_ASSERT( FIELD_OFFSET(struct get_process_info_reply, machine) == 60 ); C_ASSERT( sizeof(struct get_process_info_reply) == 64 ); C_ASSERT( FIELD_OFFSET(struct get_process_debug_info_request, handle) == 12 ); -C_ASSERT( sizeof(struct get_process_debug_info_request) == 16 ); +C_ASSERT( FIELD_OFFSET(struct get_process_debug_info_request, want_debug_obj) == 16 ); +C_ASSERT( sizeof(struct get_process_debug_info_request) == 24 ); C_ASSERT( FIELD_OFFSET(struct get_process_debug_info_reply, debug) == 8 ); C_ASSERT( FIELD_OFFSET(struct get_process_debug_info_reply, debug_children) == 12 ); C_ASSERT( sizeof(struct get_process_debug_info_reply) == 16 ); diff --git a/server/trace.c b/server/trace.c index 99c5d3996ab..d708c361602 100644 --- a/server/trace.c +++ b/server/trace.c @@ -1585,6 +1585,7 @@ static void dump_get_process_info_reply( const struct get_process_info_reply *re static void dump_get_process_debug_info_request( const struct get_process_debug_info_request *req ) { fprintf( stderr, " handle=%04x", req->handle ); + fprintf( stderr, ", want_debug_obj=%d", req->want_debug_obj ); } static void dump_get_process_debug_info_reply( const struct get_process_debug_info_reply *req ) -- 2.31.1
On 12/4/21 19:05, Jinoh Kang wrote:
Today, Wine uses NtQueryInformationProcess/ProcessDebugPort to detect whether the current process is being debugged. If it is, the process issues a breakpoint to yield control to the debugger.
Some debuggers (e.g. latest CDB) appear to create debug handles with restricted DACL, which causes querying debug port to fail with STATUS_ACCESS_DENIED. This results in the debuggee erroneously skipping the initial breakpoint.
Fix this by making retrieval of debug port object handle optional. Also, skip debug port object handle retrieval if serving requests that don't need it (i.e. ProcessDebugPort and ProcessDebugFlags).
So it looks like ProcessDebugPort, ProcessDebugFlags are currently leaking debug object handle? Probably worth fixing as a separate patch. Then, I suspect that maybe always querying the debug object handle with DEBUG_ALL_ACCESS is what is not quite right at the first place? Shouldn't it maybe return the debug object with available permissions in ProcessDebugObjectHandle? That probably deserves a test, and if that is the case returning the debug object handle with the available permissions will probably fix both the concerned issue and ProcessDebugObjectHandle implementation. Also, we do not include automatically generated changes (make_requests) in the patches, they are generated during upstream commit.
On 12/6/21 22:51, Paul Gofman wrote:
On 12/4/21 19:05, Jinoh Kang wrote:
Today, Wine uses NtQueryInformationProcess/ProcessDebugPort to detect whether the current process is being debugged. If it is, the process issues a breakpoint to yield control to the debugger.
Some debuggers (e.g. latest CDB) appear to create debug handles with restricted DACL, which causes querying debug port to fail with STATUS_ACCESS_DENIED. This results in the debuggee erroneously skipping the initial breakpoint.
Fix this by making retrieval of debug port object handle optional. Also, skip debug port object handle retrieval if serving requests that don't need it (i.e. ProcessDebugPort and ProcessDebugFlags).
So it looks like ProcessDebugPort, ProcessDebugFlags are currently leaking debug object handle? Probably worth fixing as a separate patch.
No, the current code is correct with respect to resource management. Thus:
This also eliminates the extra round trip to the server for closing the unneeded debug port object handle.
Then, I suspect that maybe always querying the debug object handle with DEBUG_ALL_ACCESS is what is not quite right at the first place? Shouldn't it maybe return the debug object with available permissions in ProcessDebugObjectHandle?
Okay, looks like MAXIMUM_ALLOWED would be a better fit.
That probably deserves a test,
and if that is the case returning the debug object handle with the available permissions will probably fix both the concerned issue and ProcessDebugObjectHandle implementation.
Partly it should, but not completely. ProcessDebugPort and ProcessDebugFlags shall succeed even if the caller doesn't have access to the debug port object at all. In fact, it seems to be a known "anti-anti-debugging" trick to create the debug port with highly restricted DACL, which makes querying for ProcessDebugObjectHandle fail with STATUS_ACCESS_DENIED; however, this does not apply to ProcessDebugPort and ProcessDebugFlags. In order to replicate this behaviour, we need both fixes: 1. ProcessDebugObjectHandle shall open the object with MAXIMUM_ALLOWED (will probably fix the CDB case in particular) 2. ProcessDebugPort and ProcessDebugFlags shall not open the object at all (will replicate Windows behaviour and also avoid another round trip for NtClose)
Also, we do not include automatically generated changes (make_requests) in the patches, they are generated during upstream commit.
Thanks! -- Sincerely, Jinoh Kang
participants (2)
-
Jinoh Kang -
Paul Gofman