aboutsummaryrefslogtreecommitdiffstats
path: root/ipc
diff options
context:
space:
mode:
Diffstat (limited to 'ipc')
-rw-r--r--ipc/util.c71
-rw-r--r--ipc/util.h2
2 files changed, 59 insertions, 14 deletions
diff --git a/ipc/util.c b/ipc/util.c
index 03eadd8fb0fd..813804ebdeba 100644
--- a/ipc/util.c
+++ b/ipc/util.c
@@ -669,38 +669,81 @@ void ipc64_perm_to_ipc_perm (struct ipc64_perm *in, struct ipc_perm *out)
}
/**
+ * ipc_obtain_object
+ * @ids: ipc identifier set
+ * @id: ipc id to look for
+ *
+ * Look for an id in the ipc ids idr and return associated ipc object.
+ *
+ * Call inside the RCU critical section.
+ * The ipc object is *not* locked on exit.
+ */
+struct kern_ipc_perm *ipc_obtain_object(struct ipc_ids *ids, int id)
+{
+ struct kern_ipc_perm *out;
+ int lid = ipcid_to_idx(id);
+
+ out = idr_find(&ids->ipcs_idr, lid);
+ if (!out)
+ return ERR_PTR(-EINVAL);
+
+ return out;
+}
+
+/**
* ipc_lock - Lock an ipc structure without rw_mutex held
* @ids: IPC identifier set
* @id: ipc id to look for
*
* Look for an id in the ipc ids idr and lock the associated ipc object.
*
- * The ipc object is locked on exit.
+ * The ipc object is locked on successful exit.
*/
-
struct kern_ipc_perm *ipc_lock(struct ipc_ids *ids, int id)
{
struct kern_ipc_perm *out;
- int lid = ipcid_to_idx(id);
rcu_read_lock();
- out = idr_find(&ids->ipcs_idr, lid);
- if (out == NULL) {
- rcu_read_unlock();
- return ERR_PTR(-EINVAL);
- }
+ out = ipc_obtain_object(ids, id);
+ if (IS_ERR(out))
+ goto err1;
spin_lock(&out->lock);
-
+
/* ipc_rmid() may have already freed the ID while ipc_lock
* was spinning: here verify that the structure is still valid
*/
- if (out->deleted) {
- spin_unlock(&out->lock);
- rcu_read_unlock();
- return ERR_PTR(-EINVAL);
- }
+ if (!out->deleted)
+ return out;
+ spin_unlock(&out->lock);
+ out = ERR_PTR(-EINVAL);
+err1:
+ rcu_read_unlock();
+ return out;
+}
+
+/**
+ * ipc_obtain_object_check
+ * @ids: ipc identifier set
+ * @id: ipc id to look for
+ *
+ * Similar to ipc_obtain_object() but also checks
+ * the ipc object reference counter.
+ *
+ * Call inside the RCU critical section.
+ * The ipc object is *not* locked on exit.
+ */
+struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id)
+{
+ struct kern_ipc_perm *out = ipc_obtain_object(ids, id);
+
+ if (IS_ERR(out))
+ goto out;
+
+ if (ipc_checkid(out, id))
+ return ERR_PTR(-EIDRM);
+out:
return out;
}
diff --git a/ipc/util.h b/ipc/util.h
index ac1480a4efd1..bfc8d4ea6e46 100644
--- a/ipc/util.h
+++ b/ipc/util.h
@@ -123,6 +123,7 @@ void ipc_rcu_getref(void *ptr);
void ipc_rcu_putref(void *ptr);
struct kern_ipc_perm *ipc_lock(struct ipc_ids *, int);
+struct kern_ipc_perm *ipc_obtain_object(struct ipc_ids *ids, int id);
void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out);
void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out);
@@ -168,6 +169,7 @@ static inline void ipc_unlock(struct kern_ipc_perm *perm)
}
struct kern_ipc_perm *ipc_lock_check(struct ipc_ids *ids, int id);
+struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id);
int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
struct ipc_ops *ops, struct ipc_params *params);
void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids,

Privacy Policy