Simplified cap id finding and destroying it.

It is not very straightforward to reach a capabilities list. We
now use a single function to find out a capability by its id and
its list, since the two are used frequently together (i.e. cap
removal and destruction)

include/l4/generic/capability.h

@@ -146,9 +146,7 @@ struct capability *capability_find_by_rtype(struct ktcb *task,
 
 struct capability *cap_list_find_by_rtype(struct cap_list *clist,
 					  unsigned int rtype);
-struct capability *cap_find_byid(l4id_t capid);
+struct capability *cap_find_by_capid(l4id_t capid, struct cap_list **clist);
-
-int cap_find_destroy(l4id_t capid);
 
 /* Capability checking on system calls */
 int cap_map_check(struct ktcb *task, unsigned long phys, unsigned long virt,

src/api/cap.c

@@ -61,15 +61,16 @@ int cap_read_all(struct capability *caparray)
 int cap_share_single(l4id_t capid)
 {
 	struct capability *cap;
+	struct cap_list *clist;
 
-	if (!(cap = cap_find_byid(capid)))
+	if (!(cap = cap_find_by_capid(capid, &clist)))
 		return -EEXIST;
 
 	if (cap->owner != current->tid)
 		return -EPERM;
 
 	/* First remove it from its list */
-	list_remove(&cap->list);
+	cap_list_remove(cap, clist);
 
 	/* Place it where it is shared */
 	cap_list_insert(cap, &curcont->cap_list);
@@ -145,9 +146,10 @@ out_err:
 int cap_grant_single(struct capability *req, unsigned int flags)
 {
 	struct capability *cap;
+	struct cap_list *clist;
 	struct ktcb *target;
 
-	if (!(cap = cap_find_byid(req->capid)))
+	if (!(cap = cap_find_by_capid(req->capid, &clist)))
 		return -EEXIST;
 
 	if (!(target = tcb_find(req->owner)))
@@ -161,7 +163,7 @@ int cap_grant_single(struct capability *req, unsigned int flags)
 		return -EPERM;
 
 	/* First remove it from its list */
-	list_remove(&cap->list);
+	cap_list_remove(cap, clist);
 
 	/* Change ownership */
 	cap->owner = target->tid;
@@ -272,10 +274,11 @@ int cap_deduce_rtype(struct capability *orig, struct capability *new)
 int cap_deduce(struct capability *new)
 {
 	struct capability *orig;
+	struct cap_list *clist;
 	int ret;
 
 	/* Find original capability */
-	if (!(orig = cap_find_byid(new->capid)))
+	if (!(orig = cap_find_by_capid(new->capid, &clist)))
 		return -EEXIST;
 
 	/* Check that caller is owner */
@@ -353,9 +356,10 @@ int cap_deduce(struct capability *new)
 int cap_destroy(struct capability *cap)
 {
 	struct capability *orig;
+	struct cap_list *clist;
 
 	/* Find original capability */
-	if (!(orig = cap_find_byid(cap->capid)))
+	if (!(orig = cap_find_by_capid(cap->capid, &clist)))
 		return -EEXIST;
 
 	/* Check that caller is owner */
@@ -366,7 +370,8 @@ int cap_destroy(struct capability *cap)
 	if (!(cap_generic_perms(orig) & CAP_CHANGEABLE))
 		return -ENOCAP;
 
-	cap_find_destroy(cap->capid);
+	cap_list_remove(orig, clist);
+	free_capability(orig);
 	return 0;
 }
 
@@ -399,10 +404,11 @@ static inline int cap_has_range(struct capability *c)
 int cap_split(struct capability *diff, unsigned int flags)
 {
 	struct capability *orig, *new;
+	struct cap_list *clist;
 	int ret;
 
 	/* Find original capability */
-	if (!(orig = cap_find_byid(diff->capid)))
+	if (!(orig = cap_find_by_capid(diff->capid, &clist)))
 		return -EEXIST;
 
 	/* Check target type/resid/owner is the same */
@@ -576,9 +582,10 @@ out_err:
 int cap_replicate(struct capability *dupl)
 {
 	struct capability *new, *orig;
+	struct cap_list *clist;
 
 	/* Find original capability */
-	if (!(orig = cap_find_byid(dupl->capid)))
+	if (!(orig = cap_find_by_capid(dupl->capid, &clist)))
 		return -EEXIST;
 
 	/* Check that caller is owner */

src/generic/capability.c

@@ -128,70 +128,35 @@ struct capability *capability_find_by_rtype(struct ktcb *task,
 	return 0;
 }
 
-/*
+struct capability *cap_find_by_capid(l4id_t capid, struct cap_list **cap_list)
- * FIXME: Make these functions pass a match function to cap_find()
- * and remove all duplication. Same goes for find_rtype.
- */
-struct capability *cap_find_byid(l4id_t capid)
 {
 	struct capability *cap;
 	struct ktcb *task = current;
 
 	/* Search task's own list */
 	list_foreach_struct(cap, &task->cap_list.caps, list)
-		if (cap->capid == capid)
+		if (cap->capid == capid) {
+			*cap_list = &task->cap_list;
 			return cap;
+		}
 
 	/* Search space list */
 	list_foreach_struct(cap, &task->space->cap_list.caps, list)
-		if (cap->capid == capid)
+		if (cap->capid == capid) {
+			*cap_list = &task->space->cap_list;
 			return cap;
+		}
 
 	/* Search container list */
 	list_foreach_struct(cap, &task->container->cap_list.caps, list)
-		if (cap->capid == capid)
+		if (cap->capid == capid) {
+			*cap_list = &task->container->cap_list;
 			return cap;
+		}
 
 	return 0;
 }
 
-/*
- * TODO: Instead of destroying, use cap_find_byid match function's
- * match_args to pass a pointer to the capability list, so the
- * caller may destroy it
- */
-int cap_find_destroy(l4id_t capid)
-{
-	struct capability *cap;
-	struct ktcb *task = current;
-
-	/* Search task's own list */
-	list_foreach_struct(cap, &task->cap_list.caps, list)
-		if (cap->capid == capid) {
-			cap_list_remove(cap, &task->cap_list);
-			free_capability(cap);
-			return 0;
-		}
-
-	/* Search space list */
-	list_foreach_struct(cap, &task->space->cap_list.caps, list)
-		if (cap->capid == capid) {
-			cap_list_remove(cap, &task->space->cap_list);
-			free_capability(cap);
-			return 0;
-		}
-
-	/* Search container list */
-	list_foreach_struct(cap, &task->container->cap_list.caps, list)
-		if (cap->capid == capid) {
-			cap_list_remove(cap, &task->container->cap_list);
-			free_capability(cap);
-			return 0;
-		}
-
-	return -EEXIST;
-}
-
 typedef struct capability *(*cap_match_func_t) \
 		(struct capability *cap, void *match_args);
 
@@ -543,7 +508,6 @@ struct capability *cap_match_thread(struct capability *cap,
 		if (!(cap->access & CAP_TCTRL_WAIT))
 			return 0;
 		break;
-
 	default:
 		/* We refuse to accept anything else */
 		return 0;