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xselinux: Add basic support for selection access control and redirection.

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Probably not fully baked yet.  It's difficult to test since so few apps
actually follow the ICCCM with respect to cut & paste.
This commit is contained in:
Eamon Walsh 2007-10-23 20:58:48 -04:00 committed by Eamon Walsh
parent 825f09dffd
commit 46521f5298
2 changed files with 348 additions and 60 deletions
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371
Xext/xselinux.c
View File

@ -65,6 +65,15 @@ typedef struct {
char *command;
} SELinuxStateRec;
/* selection manager */
typedef struct {
Atom selection;
security_id_t sid;
} SELinuxSelectionRec;
static ClientPtr selectionManager;
static Window selectionWindow;
/* audit file descriptor */
static int audit_fd;
@ -99,6 +108,10 @@ static unsigned numKnownTypes;
static security_id_t *knownEvents;
static unsigned numKnownEvents;
/* Array of selection SID structures */
static SELinuxSelectionRec *knownSelections;
static unsigned numKnownSelections;
/* dynamically allocated security classes and permissions */
static struct security_class_mapping map[] = {
{ "x_drawable", { "read", "write", "destroy", "create", "getattr", "setattr", "list_property", "get_property", "set_property", "", "", "list_child", "add_child", "remove_child", "hide", "show", "blend", "override", "", "", "", "", "send", "receive", "", "manage", NULL }},
@ -129,6 +142,52 @@ static pointer truep = (pointer)1;
* Support Routines
*/
/*
* Looks up the SID corresponding to the given selection atom
*/
static int
SELinuxSelectionToSID(Atom selection, SELinuxStateRec *sid_return)
{
const char *name;
unsigned i, size;
for (i = 0; i < numKnownSelections; i++)
if (knownSelections[i].selection == selection) {
sid_return->sid = knownSelections[i].sid;
return Success;
}
/* Need to increase size of array */
i = numKnownSelections;
size = (i + 1) * sizeof(SELinuxSelectionRec);
knownSelections = xrealloc(knownSelections, size);
if (!knownSelections)
return BadAlloc;
knownSelections[i].selection = selection;
/* Look in the mappings of selection names to contexts */
name = NameForAtom(selection);
if (name) {
security_context_t con;
security_id_t sid;
if (selabel_lookup(label_hnd, &con, name, SELABEL_X_SELN) < 0) {
ErrorF("XSELinux: a selection label lookup failed!\n");
return BadValue;
}
/* Get a SID for context */
if (avc_context_to_sid(con, &sid) < 0) {
ErrorF("XSELinux: a context_to_SID call failed!\n");
return BadAlloc;
}
freecon(con);
knownSelections[i].sid = sid_return->sid = sid;
} else
knownSelections[i].sid = sid_return->sid = unlabeled_sid;
return Success;
}
/*
* Looks up the SID corresponding to the given event type
*/
@ -239,11 +298,72 @@ SELinuxDoCheck(int clientIndex, SELinuxStateRec *subj, SELinuxStateRec *obj,
return Success;
}
/*
* Labels a newly connected client.
*/
static void
SELinuxLabelClient(ClientPtr client)
{
XtransConnInfo ci = ((OsCommPtr)client->osPrivate)->trans_conn;
SELinuxStateRec *state;
security_context_t ctx;
state = dixLookupPrivate(&client->devPrivates, stateKey);
sidput(state->sid);
if (_XSERVTransIsLocal(ci)) {
int fd = _XSERVTransGetConnectionNumber(ci);
struct ucred creds;
socklen_t len = sizeof(creds);
char path[PATH_MAX + 1];
size_t bytes;
/* For local clients, can get context from the socket */
if (getpeercon(fd, &ctx) < 0)
FatalError("Client %d: couldn't get context from socket\n",
client->index);
/* Try and determine the client's executable name */
memset(&creds, 0, sizeof(creds));
if (getsockopt(fd, SOL_SOCKET, SO_PEERCRED, &creds, &len) < 0)
goto finish;
snprintf(path, PATH_MAX + 1, "/proc/%d/cmdline", creds.pid);
fd = open(path, O_RDONLY);
if (fd < 0)
goto finish;
bytes = read(fd, path, PATH_MAX + 1);
close(fd);
if (bytes <= 0)
goto finish;
state->command = xalloc(bytes);
if (!state->command)
goto finish;
memcpy(state->command, path, bytes);
state->command[bytes - 1] = 0;
} else
/* For remote clients, need to use a default context */
if (selabel_lookup(label_hnd, &ctx, NULL, SELABEL_X_CLIENT) < 0)
FatalError("Client %d: couldn't get default remote context\n",
client->index);
finish:
/* Get a SID from the context */
if (avc_context_to_sid(ctx, &state->sid) < 0)
FatalError("Client %d: context_to_sid(%s) failed\n",
client->index, ctx);
freecon(ctx);
}
/*
* Labels initial server objects.
*/
static void
SELinuxFixupLabels(void)
SELinuxLabelInitial(void)
{
int i;
XaceScreenAccessRec srec;
@ -674,6 +794,28 @@ SELinuxServer(CallbackListPtr *pcbl, pointer unused, pointer calldata)
rec->status = rc;
}
static void
SELinuxSelection(CallbackListPtr *pcbl, pointer unused, pointer calldata)
{
XaceSelectionAccessRec *rec = (XaceSelectionAccessRec *)calldata;
SELinuxStateRec *subj, sel_sid;
SELinuxAuditRec auditdata = { rec->client, NULL, 0, 0, 0, NULL };
int rc;
subj = dixLookupPrivate(&rec->client->devPrivates, stateKey);
rc = SELinuxSelectionToSID(rec->name, &sel_sid);
if (rc != Success) {
rec->status = rc;
return;
}
rc = SELinuxDoCheck(rec->client->index, subj, &sel_sid,
SECCLASS_X_SELECTION, rec->access_mode, &auditdata);
if (rc != Success)
rec->status = rc;
}
/*
* DIX Callbacks
@ -683,63 +825,23 @@ static void
SELinuxClientState(CallbackListPtr *pcbl, pointer unused, pointer calldata)
{
NewClientInfoRec *pci = calldata;
ClientPtr client = pci->client;
XtransConnInfo ci = ((OsCommPtr)client->osPrivate)->trans_conn;
SELinuxStateRec *state;
security_context_t ctx;
if (client->clientState != ClientStateInitial)
return;
switch (pci->client->clientState) {
case ClientStateInitial:
SELinuxLabelClient(pci->client);
break;
state = dixLookupPrivate(&client->devPrivates, stateKey);
sidput(state->sid);
case ClientStateRetained:
case ClientStateGone:
if (pci->client == selectionManager) {
selectionManager = NULL;
selectionWindow = 0;
}
break;
if (_XSERVTransIsLocal(ci)) {
int fd = _XSERVTransGetConnectionNumber(ci);
struct ucred creds;
socklen_t len = sizeof(creds);
char path[PATH_MAX + 1];
size_t bytes;
/* For local clients, can get context from the socket */
if (getpeercon(fd, &ctx) < 0)
FatalError("Client %d: couldn't get context from socket\n",
client->index);
/* Try and determine the client's executable name */
memset(&creds, 0, sizeof(creds));
if (getsockopt(fd, SOL_SOCKET, SO_PEERCRED, &creds, &len) < 0)
goto finish;
snprintf(path, PATH_MAX + 1, "/proc/%d/cmdline", creds.pid);
fd = open(path, O_RDONLY);
if (fd < 0)
goto finish;
bytes = read(fd, path, PATH_MAX + 1);
close(fd);
if (bytes <= 0)
goto finish;
state->command = xalloc(bytes);
if (!state->command)
goto finish;
memcpy(state->command, path, bytes);
state->command[bytes - 1] = 0;
} else
/* For remote clients, need to use a default context */
if (selabel_lookup(label_hnd, &ctx, NULL, SELABEL_X_CLIENT) < 0)
FatalError("Client %d: couldn't get default remote context\n",
client->index);
finish:
/* Get a SID from the context */
if (avc_context_to_sid(ctx, &state->sid) < 0)
FatalError("Client %d: context_to_sid(%s) failed\n",
client->index, ctx);
freecon(ctx);
default:
break;
}
}
static void
@ -788,6 +890,50 @@ SELinuxResourceState(CallbackListPtr *pcbl, pointer unused, pointer calldata)
FatalError("XSELinux: Unexpected unlabeled window found\n");
}
static void
SELinuxSelectionState(CallbackListPtr *pcbl, pointer unused, pointer calldata)
{
SelectionInfoRec *rec = calldata;
SELinuxStateRec *subj, *obj;
switch (rec->kind) {
case SelectionSetOwner:
/* save off the "real" owner of the selection */
rec->selection->alt_client = rec->selection->client;
rec->selection->alt_window = rec->selection->window;
/* figure out the new label for the content */
subj = dixLookupPrivate(&rec->client->devPrivates, stateKey);
obj = dixLookupPrivate(&rec->selection->devPrivates, stateKey);
sidput(obj->sid);
if (avc_compute_create(subj->sid, subj->sid, SECCLASS_X_SELECTION,
&obj->sid) < 0) {
ErrorF("XSELinux: a compute_create call failed!\n");
obj->sid = unlabeled_sid;
}
break;
case SelectionGetOwner:
/* restore the real owner */
rec->selection->window = rec->selection->alt_window;
break;
case SelectionConvertSelection:
/* redirect the convert request if necessary */
if (selectionManager && selectionManager != rec->client) {
rec->selection->client = selectionManager;
rec->selection->window = selectionWindow;
} else {
rec->selection->client = rec->selection->alt_client;
rec->selection->window = rec->selection->alt_window;
}
break;
default:
break;
}
}
/*
* DevPrivates Callbacks
@ -822,10 +968,109 @@ SELinuxStateFree(CallbackListPtr *pcbl, pointer unused, pointer calldata)
* Extension Dispatch
*/
static int
ProcSELinuxQueryVersion(ClientPtr client)
{
SELinuxQueryVersionReply rep;
/*
REQUEST(SELinuxQueryVersionReq);
REQUEST_SIZE_MATCH (SELinuxQueryVersionReq);
*/
rep.type = X_Reply;
rep.length = 0;
rep.sequenceNumber = client->sequence;
rep.server_major = XSELINUX_MAJOR_VERSION;
rep.server_minor = XSELINUX_MINOR_VERSION;
if (client->swapped) {
int n;
swaps(&rep.sequenceNumber, n);
swapl(&rep.length, n);
swaps(&rep.server_major, n);
swaps(&rep.server_minor, n);
}
WriteToClient(client, sizeof(rep), (char *)&rep);
return (client->noClientException);
}
static int
ProcSELinuxSetSelectionManager(ClientPtr client)
{
REQUEST(SELinuxSetSelectionManagerReq);
WindowPtr pWin;
int rc;
REQUEST_SIZE_MATCH(SELinuxSetSelectionManagerReq);
if (stuff->window == None) {
selectionManager = NULL;
selectionWindow = None;
} else {
rc = dixLookupResource((pointer *)&pWin, stuff->window, RT_WINDOW,
client, DixGetAttrAccess);
if (rc != Success)
return rc;
selectionManager = client;
selectionWindow = stuff->window;
}
return Success;
}
static int
ProcSELinuxDispatch(ClientPtr client)
{
return BadRequest;
REQUEST(xReq);
switch (stuff->data) {
case X_SELinuxQueryVersion:
return ProcSELinuxQueryVersion(client);
case X_SELinuxSetSelectionManager:
return ProcSELinuxSetSelectionManager(client);
default:
return BadRequest;
}
}
static int
SProcSELinuxQueryVersion(ClientPtr client)
{
REQUEST(SELinuxQueryVersionReq);
int n;
REQUEST_SIZE_MATCH (SELinuxQueryVersionReq);
swaps(&stuff->client_major,n);
swaps(&stuff->client_minor,n);
return ProcSELinuxQueryVersion(client);
}
static int
SProcSELinuxSetSelectionManager(ClientPtr client)
{
REQUEST(SELinuxSetSelectionManagerReq);
int n;
REQUEST_SIZE_MATCH (SELinuxSetSelectionManagerReq);
swapl(&stuff->window,n);
return ProcSELinuxSetSelectionManager(client);
}
static int
SProcSELinuxDispatch(ClientPtr client)
{
REQUEST(xReq);
int n;
swaps(&stuff->length, n);
switch (stuff->data) {
case X_SELinuxQueryVersion:
return SProcSELinuxQueryVersion(client);
case X_SELinuxSetSelectionManager:
return SProcSELinuxSetSelectionManager(client);
default:
return BadRequest;
}
}
@ -839,6 +1084,7 @@ SELinuxResetProc(ExtensionEntry *extEntry)
/* Unregister callbacks */
DeleteCallback(&ClientStateCallback, SELinuxClientState, NULL);
DeleteCallback(&ResourceStateCallback, SELinuxResourceState, NULL);
DeleteCallback(&SelectionCallback, SELinuxSelectionState, NULL);
XaceDeleteCallback(XACE_EXT_DISPATCH, SELinuxExtension, NULL);
XaceDeleteCallback(XACE_RESOURCE_ACCESS, SELinuxResource, NULL);
@ -849,7 +1095,7 @@ SELinuxResetProc(ExtensionEntry *extEntry)
XaceDeleteCallback(XACE_CLIENT_ACCESS, SELinuxClient, NULL);
XaceDeleteCallback(XACE_EXT_ACCESS, SELinuxExtension, NULL);
XaceDeleteCallback(XACE_SERVER_ACCESS, SELinuxServer, NULL);
// XaceDeleteCallback(XACE_SELECTION_ACCESS, SELinuxSelection, NULL);
XaceDeleteCallback(XACE_SELECTION_ACCESS, SELinuxSelection, NULL);
XaceDeleteCallback(XACE_SCREEN_ACCESS, SELinuxScreen, NULL);
XaceDeleteCallback(XACE_SCREENSAVER_ACCESS, SELinuxScreen, truep);
@ -863,6 +1109,10 @@ SELinuxResetProc(ExtensionEntry *extEntry)
avc_active = 0;
/* Free local state */
xfree(knownSelections);
knownSelections = NULL;
numKnownSelections = 0;
xfree(knownEvents);
knownEvents = NULL;
numKnownEvents = 0;
@ -929,6 +1179,7 @@ XSELinuxExtensionInit(INITARGS)
ret &= AddCallback(&ClientStateCallback, SELinuxClientState, NULL);
ret &= AddCallback(&ResourceStateCallback, SELinuxResourceState, NULL);
ret &= AddCallback(&SelectionCallback, SELinuxSelectionState, NULL);
ret &= XaceRegisterCallback(XACE_EXT_DISPATCH, SELinuxExtension, NULL);
ret &= XaceRegisterCallback(XACE_RESOURCE_ACCESS, SELinuxResource, NULL);
@ -939,7 +1190,7 @@ XSELinuxExtensionInit(INITARGS)
ret &= XaceRegisterCallback(XACE_CLIENT_ACCESS, SELinuxClient, NULL);
ret &= XaceRegisterCallback(XACE_EXT_ACCESS, SELinuxExtension, NULL);
ret &= XaceRegisterCallback(XACE_SERVER_ACCESS, SELinuxServer, NULL);
// ret &= XaceRegisterCallback(XACE_SELECTION_ACCESS, SELinuxSelection, NULL);
ret &= XaceRegisterCallback(XACE_SELECTION_ACCESS, SELinuxSelection, NULL);
ret &= XaceRegisterCallback(XACE_SCREEN_ACCESS, SELinuxScreen, NULL);
ret &= XaceRegisterCallback(XACE_SCREENSAVER_ACCESS, SELinuxScreen, truep);
if (!ret)
@ -948,9 +1199,9 @@ XSELinuxExtensionInit(INITARGS)
/* Add extension to server */
extEntry = AddExtension(XSELINUX_EXTENSION_NAME,
XSELinuxNumberEvents, XSELinuxNumberErrors,
ProcSELinuxDispatch, ProcSELinuxDispatch,
ProcSELinuxDispatch, SProcSELinuxDispatch,
SELinuxResetProc, StandardMinorOpcode);
/* Label objects that were created before we could register ourself */
SELinuxFixupLabels();
SELinuxLabelInitial();
}

37
Xext/xselinux.h
View File

@ -29,6 +29,43 @@ CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
#define XSELinuxNumberEvents 0
#define XSELinuxNumberErrors 0
/* Extension protocol */
#define X_SELinuxQueryVersion 0
#define X_SELinuxSetSelectionManager 1
typedef struct _SELinuxQueryVersion {
CARD8 reqType;
CARD8 SELinuxReqType;
CARD16 length;
CARD8 client_major;
CARD8 client_minor;
CARD16 unused;
} SELinuxQueryVersionReq;
#define sz_SELinuxQueryVersionReq 8
typedef struct {
CARD8 type;
CARD8 pad1;
CARD16 sequenceNumber;
CARD32 length;
CARD16 server_major;
CARD16 server_minor;
CARD32 pad2;
CARD32 pad3;
CARD32 pad4;
CARD32 pad5;
CARD32 pad6;
} SELinuxQueryVersionReply;
#define sz_SELinuxQueryVersionReply 32
typedef struct _SELinuxSetSelectionManager {
CARD8 reqType;
CARD8 SELinuxReqType;
CARD16 length;
CARD32 window;
} SELinuxSetSelectionManagerReq;
#define sz_SELinuxSetSelectionManagerReq 8
/* Private Flask definitions */
#define SECCLASS_X_DRAWABLE 1
#define SECCLASS_X_SCREEN 2