382 lines
9.1 KiB
C
382 lines
9.1 KiB
C
/************************************************************
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Author: Eamon Walsh <ewalsh@tycho.nsa.gov>
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Permission to use, copy, modify, distribute, and sell this software and its
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documentation for any purpose is hereby granted without fee, provided that
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this permission notice appear in supporting documentation. This permission
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notice shall be included in all copies or substantial portions of the
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Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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AUTHOR BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
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AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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********************************************************/
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#ifdef HAVE_DIX_CONFIG_H
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#include <dix-config.h>
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#endif
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#include <selinux/label.h>
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#include "registry.h"
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#include "xselinuxint.h"
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/* selection and property atom cache */
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typedef struct {
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SELinuxObjectRec prp;
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SELinuxObjectRec sel;
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} SELinuxAtomRec;
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/* dynamic array */
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typedef struct {
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unsigned size;
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void **array;
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} SELinuxArrayRec;
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/* labeling handle */
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static struct selabel_handle *label_hnd;
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/* Array of object classes indexed by resource type */
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SELinuxArrayRec arr_types;
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/* Array of event SIDs indexed by event type */
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SELinuxArrayRec arr_events;
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/* Array of property and selection SID structures */
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SELinuxArrayRec arr_atoms;
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/*
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* Dynamic array helpers
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*/
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static void *
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SELinuxArrayGet(SELinuxArrayRec *rec, unsigned key)
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{
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return (rec->size > key) ? rec->array[key] : 0;
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}
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static int
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SELinuxArraySet(SELinuxArrayRec *rec, unsigned key, void *val)
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{
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if (key >= rec->size) {
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/* Need to increase size of array */
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rec->array = xrealloc(rec->array, (key + 1) * sizeof(val));
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if (!rec->array)
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return FALSE;
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memset(rec->array + rec->size, 0, (key - rec->size + 1) * sizeof(val));
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rec->size = key + 1;
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}
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rec->array[key] = val;
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return TRUE;
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}
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static void
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SELinuxArrayFree(SELinuxArrayRec *rec, int free_elements)
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{
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if (free_elements) {
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unsigned i = rec->size;
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while (i)
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xfree(rec->array[--i]);
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}
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xfree(rec->array);
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rec->size = 0;
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rec->array = NULL;
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}
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/*
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* Looks up a name in the selection or property mappings
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*/
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static int
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SELinuxAtomToSIDLookup(Atom atom, SELinuxObjectRec *obj, int map, int polymap)
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{
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const char *name = NameForAtom(atom);
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security_context_t ctx;
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int rc = Success;
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obj->poly = 1;
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/* Look in the mappings of names to contexts */
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if (selabel_lookup_raw(label_hnd, &ctx, name, map) == 0) {
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obj->poly = 0;
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} else if (errno != ENOENT) {
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ErrorF("SELinux: a property label lookup failed!\n");
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return BadValue;
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} else if (selabel_lookup_raw(label_hnd, &ctx, name, polymap) < 0) {
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ErrorF("SELinux: a property label lookup failed!\n");
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return BadValue;
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}
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/* Get a SID for context */
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if (avc_context_to_sid_raw(ctx, &obj->sid) < 0) {
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ErrorF("SELinux: a context_to_SID_raw call failed!\n");
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rc = BadAlloc;
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}
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freecon(ctx);
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return rc;
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}
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/*
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* Looks up the SID corresponding to the given property or selection atom
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*/
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int
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SELinuxAtomToSID(Atom atom, int prop, SELinuxObjectRec **obj_rtn)
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{
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SELinuxAtomRec *rec;
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SELinuxObjectRec *obj;
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int rc, map, polymap;
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rec = SELinuxArrayGet(&arr_atoms, atom);
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if (!rec) {
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rec = xcalloc(1, sizeof(SELinuxAtomRec));
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if (!rec || !SELinuxArraySet(&arr_atoms, atom, rec))
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return BadAlloc;
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}
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if (prop) {
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obj = &rec->prp;
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map = SELABEL_X_PROP;
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polymap = SELABEL_X_POLYPROP;
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} else {
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obj = &rec->sel;
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map = SELABEL_X_SELN;
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polymap = SELABEL_X_POLYSELN;
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}
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if (!obj->sid) {
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rc = SELinuxAtomToSIDLookup(atom, obj, map, polymap);
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if (rc != Success)
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goto out;
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}
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*obj_rtn = obj;
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rc = Success;
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out:
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return rc;
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}
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/*
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* Looks up a SID for a selection/subject pair
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*/
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int
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SELinuxSelectionToSID(Atom selection, SELinuxSubjectRec *subj,
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security_id_t *sid_rtn, int *poly_rtn)
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{
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int rc;
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SELinuxObjectRec *obj;
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security_id_t tsid;
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/* Get the default context and polyinstantiation bit */
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rc = SELinuxAtomToSID(selection, 0, &obj);
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if (rc != Success)
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return rc;
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/* Check for an override context next */
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if (subj->sel_use_sid) {
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sidget(tsid = subj->sel_use_sid);
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goto out;
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}
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sidget(tsid = obj->sid);
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/* Polyinstantiate if necessary to obtain the final SID */
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if (obj->poly) {
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sidput(tsid);
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if (avc_compute_member(subj->sid, obj->sid,
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SECCLASS_X_SELECTION, &tsid) < 0) {
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ErrorF("SELinux: a compute_member call failed!\n");
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return BadValue;
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}
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}
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out:
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*sid_rtn = tsid;
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if (poly_rtn)
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*poly_rtn = obj->poly;
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return Success;
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}
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/*
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* Looks up a SID for a property/subject pair
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*/
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int
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SELinuxPropertyToSID(Atom property, SELinuxSubjectRec *subj,
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security_id_t *sid_rtn, int *poly_rtn)
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{
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int rc;
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SELinuxObjectRec *obj;
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security_id_t tsid, tsid2;
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/* Get the default context and polyinstantiation bit */
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rc = SELinuxAtomToSID(property, 1, &obj);
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if (rc != Success)
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return rc;
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/* Check for an override context next */
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if (subj->prp_use_sid) {
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sidget(tsid = subj->prp_use_sid);
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goto out;
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}
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/* Perform a transition */
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if (avc_compute_create(subj->sid, obj->sid,
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SECCLASS_X_PROPERTY, &tsid) < 0) {
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ErrorF("SELinux: a compute_create call failed!\n");
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return BadValue;
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}
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/* Polyinstantiate if necessary to obtain the final SID */
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if (obj->poly) {
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tsid2 = tsid;
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if (avc_compute_member(subj->sid, tsid2,
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SECCLASS_X_PROPERTY, &tsid) < 0) {
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ErrorF("SELinux: a compute_member call failed!\n");
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sidput(tsid2);
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return BadValue;
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}
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sidput(tsid2);
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}
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out:
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*sid_rtn = tsid;
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if (poly_rtn)
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*poly_rtn = obj->poly;
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return Success;
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}
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/*
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* Looks up the SID corresponding to the given event type
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*/
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int
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SELinuxEventToSID(unsigned type, security_id_t sid_of_window,
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SELinuxObjectRec *sid_return)
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{
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const char *name = LookupEventName(type);
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security_id_t sid;
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security_context_t ctx;
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type &= 127;
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sid = SELinuxArrayGet(&arr_events, type);
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if (!sid) {
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/* Look in the mappings of event names to contexts */
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if (selabel_lookup_raw(label_hnd, &ctx, name, SELABEL_X_EVENT) < 0) {
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ErrorF("SELinux: an event label lookup failed!\n");
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return BadValue;
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}
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/* Get a SID for context */
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if (avc_context_to_sid_raw(ctx, &sid) < 0) {
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ErrorF("SELinux: a context_to_SID_raw call failed!\n");
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freecon(ctx);
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return BadAlloc;
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}
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freecon(ctx);
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/* Cache the SID value */
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if (!SELinuxArraySet(&arr_events, type, sid)) {
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sidput(sid);
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return BadAlloc;
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}
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}
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/* Perform a transition to obtain the final SID */
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if (avc_compute_create(sid_of_window, sid, SECCLASS_X_EVENT,
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&sid_return->sid) < 0) {
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ErrorF("SELinux: a compute_create call failed!\n");
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return BadValue;
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}
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return Success;
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}
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int
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SELinuxExtensionToSID(const char *name, security_id_t *sid_rtn)
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{
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security_context_t ctx;
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/* Look in the mappings of extension names to contexts */
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if (selabel_lookup_raw(label_hnd, &ctx, name, SELABEL_X_EXT) < 0) {
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ErrorF("SELinux: a property label lookup failed!\n");
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return BadValue;
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}
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/* Get a SID for context */
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if (avc_context_to_sid_raw(ctx, sid_rtn) < 0) {
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ErrorF("SELinux: a context_to_SID_raw call failed!\n");
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freecon(ctx);
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return BadAlloc;
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}
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freecon(ctx);
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return Success;
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}
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/*
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* Returns the object class corresponding to the given resource type.
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*/
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security_class_t
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SELinuxTypeToClass(RESTYPE type)
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{
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void *tmp;
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tmp = SELinuxArrayGet(&arr_types, type & TypeMask);
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if (!tmp) {
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unsigned long class = SECCLASS_X_RESOURCE;
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if (type & RC_DRAWABLE)
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class = SECCLASS_X_DRAWABLE;
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else if (type == RT_GC)
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class = SECCLASS_X_GC;
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else if (type == RT_FONT)
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class = SECCLASS_X_FONT;
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else if (type == RT_CURSOR)
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class = SECCLASS_X_CURSOR;
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else if (type == RT_COLORMAP)
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class = SECCLASS_X_COLORMAP;
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else {
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/* Need to do a string lookup */
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const char *str = LookupResourceName(type);
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if (!strcmp(str, "PICTURE"))
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class = SECCLASS_X_DRAWABLE;
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else if (!strcmp(str, "GLYPHSET"))
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class = SECCLASS_X_FONT;
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}
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tmp = (void *)class;
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SELinuxArraySet(&arr_types, type & TypeMask, tmp);
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}
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return (security_class_t)(unsigned long)tmp;
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}
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security_context_t
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SELinuxDefaultClientLabel(void)
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{
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security_context_t ctx;
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if (selabel_lookup_raw(label_hnd, &ctx, "remote", SELABEL_X_CLIENT) < 0)
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FatalError("SELinux: failed to look up remote-client context\n");
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return ctx;
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}
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void
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SELinuxLabelInit(void)
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{
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struct selinux_opt selabel_option = { SELABEL_OPT_VALIDATE, (char *)1 };
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label_hnd = selabel_open(SELABEL_CTX_X, &selabel_option, 1);
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if (!label_hnd)
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FatalError("SELinux: Failed to open x_contexts mapping in policy\n");
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}
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void
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SELinuxLabelReset(void)
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{
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selabel_close(label_hnd);
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label_hnd = NULL;
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/* Free local state */
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SELinuxArrayFree(&arr_types, 0);
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SELinuxArrayFree(&arr_events, 0);
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SELinuxArrayFree(&arr_atoms, 1);
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}
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