IB/uverbs: Handle IDR and FD types without truncation

Our ABI for write() uses a s32 for FDs and a u32 for IDRs, but internally
we ended up implicitly casting these ABI values into an 'int'. For ioctl()
we use a s64 for FDs and a u64 for IDRs, again casting to an int.

The various casts to int are all missing range checks which can cause
userspace values that should be considered invalid to be accepted.

Fix this by making the generic lookup routine accept a s64, which does not
truncate the write API's u32/s32 or the ioctl API's s64. Then push the
detailed range checking down to the actual type implementations to be
shared by both interfaces.

Finally, change the copy of the uobj->id to sign extend into a s64, so eg,
if we ever wish to return a negative value for a FD it is carried
properly.

This ensures that userspace values are never weirdly interpreted due to
the various trunctations and everything that is really out of range gets
an EINVAL.

Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

drivers/infiniband/core/rdma_core.c

@@ -133,7 +133,7 @@ static int uverbs_try_lock_object(struct ib_uobject *uobj, bool exclusive)
  * returns success_res on success (negative errno on failure). For use by
  * callers that do not need the uobj.
  */
-int __uobj_perform_destroy(const struct uverbs_obj_type *type, int id,
+int __uobj_perform_destroy(const struct uverbs_obj_type *type, u32 id,
 			   struct ib_uverbs_file *ufile, int success_res)
 {
 	struct ib_uobject *uobj;
@@ -212,13 +212,17 @@ static void uverbs_idr_remove_uobj(struct ib_uobject *uobj)
 /* Returns the ib_uobject or an error. The caller should check for IS_ERR. */
 static struct ib_uobject *
 lookup_get_idr_uobject(const struct uverbs_obj_type *type,
-		       struct ib_uverbs_file *ufile, int id, bool exclusive)
+		       struct ib_uverbs_file *ufile, s64 id, bool exclusive)
 {
 	struct ib_uobject *uobj;
+	unsigned long idrno = id;
+
+	if (id < 0 || id > ULONG_MAX)
+		return ERR_PTR(-EINVAL);
 
 	rcu_read_lock();
 	/* object won't be released as we're protected in rcu */
-	uobj = idr_find(&ufile->idr, id);
+	uobj = idr_find(&ufile->idr, idrno);
 	if (!uobj) {
 		uobj = ERR_PTR(-ENOENT);
 		goto free;
@@ -240,17 +244,21 @@ free:
 
 static struct ib_uobject *lookup_get_fd_uobject(const struct uverbs_obj_type *type,
 						struct ib_uverbs_file *ufile,
-						int id, bool exclusive)
+						s64 id, bool exclusive)
 {
 	struct file *f;
 	struct ib_uobject *uobject;
+	int fdno = id;
 	const struct uverbs_obj_fd_type *fd_type =
 		container_of(type, struct uverbs_obj_fd_type, type);
 
+	if (fdno != id)
+		return ERR_PTR(-EINVAL);
+
 	if (exclusive)
 		return ERR_PTR(-EOPNOTSUPP);
 
-	f = fget(id);
+	f = fget(fdno);
 	if (!f)
 		return ERR_PTR(-EBADF);
 
@@ -270,7 +278,7 @@ static struct ib_uobject *lookup_get_fd_uobject(const struct uverbs_obj_type *ty
 }
 
 struct ib_uobject *rdma_lookup_get_uobject(const struct uverbs_obj_type *type,
-					   struct ib_uverbs_file *ufile, int id,
+					   struct ib_uverbs_file *ufile, s64 id,
 					   bool exclusive)
 {
 	struct ib_uobject *uobj;
@@ -725,7 +733,7 @@ EXPORT_SYMBOL(uverbs_fd_class);
 struct ib_uobject *
 uverbs_get_uobject_from_file(const struct uverbs_obj_type *type_attrs,
 			     struct ib_uverbs_file *ufile,
-			     enum uverbs_obj_access access, int id)
+			     enum uverbs_obj_access access, s64 id)
 {
 	switch (access) {
 	case UVERBS_ACCESS_READ:

drivers/infiniband/core/rdma_core.h

@@ -86,7 +86,7 @@ void uverbs_close_fd(struct file *f);
 struct ib_uobject *
 uverbs_get_uobject_from_file(const struct uverbs_obj_type *type_attrs,
 			     struct ib_uverbs_file *ufile,
-			     enum uverbs_obj_access access, int id);
+			     enum uverbs_obj_access access, s64 id);
 
 /*
  * Note that certain finalize stages could return a status:

drivers/infiniband/core/uverbs_cmd.c

@@ -48,10 +48,10 @@
 #include "core_priv.h"
 
 static struct ib_uverbs_completion_event_file *
-ib_uverbs_lookup_comp_file(int fd, struct ib_uverbs_file *ufile)
+_ib_uverbs_lookup_comp_file(s32 fd, struct ib_uverbs_file *ufile)
 {
-	struct ib_uobject *uobj = uobj_get_read(UVERBS_OBJECT_COMP_CHANNEL,
-						fd, ufile);
+	struct ib_uobject *uobj = ufd_get_read(UVERBS_OBJECT_COMP_CHANNEL,
+					       fd, ufile);
 
 	if (IS_ERR(uobj))
 		return (void *)uobj;
@@ -62,6 +62,8 @@ ib_uverbs_lookup_comp_file(int fd, struct ib_uverbs_file *ufile)
 	return container_of(uobj, struct ib_uverbs_completion_event_file,
 			    uobj);
 }
+#define ib_uverbs_lookup_comp_file(_fd, _ufile)                                \
+	_ib_uverbs_lookup_comp_file((_fd)*typecheck(s32, _fd), _ufile)
 
 ssize_t ib_uverbs_get_context(struct ib_uverbs_file *file,
 			      struct ib_device *ib_dev,

drivers/infiniband/core/uverbs_ioctl.c

@@ -136,15 +136,11 @@ static int uverbs_process_attr(struct ib_uverbs_file *ufile,
 		break;
 
 	case UVERBS_ATTR_TYPE_IDR:
-		if (uattr->data >> 32)
-			return -EINVAL;
-	/* fall through */
 	case UVERBS_ATTR_TYPE_FD:
 		if (uattr->attr_data.reserved)
 			return -EINVAL;
 
-		if (uattr->len != 0 || !ufile->ucontext ||
-		    uattr->data > INT_MAX)
+		if (uattr->len != 0 || !ufile->ucontext)
 			return -EINVAL;
 
 		o_attr = &e->obj_attr;
@@ -152,17 +148,23 @@ static int uverbs_process_attr(struct ib_uverbs_file *ufile,
 		if (!object)
 			return -EINVAL;
 
+		/*
+		 * The type of uattr->data is u64 for UVERBS_ATTR_TYPE_IDR and
+		 * s64 for UVERBS_ATTR_TYPE_FD. We can cast the u64 to s64
+		 * here without caring about truncation as we know that the
+		 * IDR implementation today rejects negative IDs
+		 */
 		o_attr->uobject = uverbs_get_uobject_from_file(
 					object->type_attrs,
 					ufile,
 					spec->u.obj.access,
-					(int)uattr->data);
+					uattr->data_s64);
 
 		if (IS_ERR(o_attr->uobject))
 			return PTR_ERR(o_attr->uobject);
 
 		if (spec->u.obj.access == UVERBS_ACCESS_NEW) {
-			u64 id = o_attr->uobject->id;
+			s64 id = o_attr->uobject->id;
 
 			/* Copy the allocated id to the user-space */
 			if (put_user(id, &e->uattr->data)) {

include/rdma/uverbs_std_types.h

@@ -46,39 +46,43 @@ static inline const struct uverbs_object_tree_def *uverbs_default_get_objects(vo
 }
 #endif
 
-static inline struct ib_uobject *__uobj_get(const struct uverbs_obj_type *type,
-					    bool write,
-					    struct ib_uverbs_file *ufile,
-					    int id)
-{
-	return rdma_lookup_get_uobject(type, ufile, id, write);
-}
+/* Returns _id, or causes a compile error if _id is not a u32.
+ *
+ * The uobj APIs should only be used with the write based uAPI to access
+ * object IDs. The write API must use a u32 for the object handle, which is
+ * checked by this macro.
+ */
+#define _uobj_check_id(_id) ((_id) * typecheck(u32, _id))
 
 #define uobj_get_type(_object) UVERBS_OBJECT(_object).type_attrs
 
 #define uobj_get_read(_type, _id, _ufile)                                      \
-	__uobj_get(uobj_get_type(_type), false, _ufile, _id)
+	rdma_lookup_get_uobject(uobj_get_type(_type), _ufile,                  \
+				_uobj_check_id(_id), false)
 
-static inline void *_uobj_get_obj_read(const struct uverbs_obj_type *type,
-				       int id, struct ib_uverbs_file *ufile)
-{
-	struct ib_uobject *uobj = __uobj_get(type, false, ufile, id);
+#define ufd_get_read(_type, _fdnum, _ufile)                                    \
+	rdma_lookup_get_uobject(uobj_get_type(_type), _ufile,                  \
+				(_fdnum)*typecheck(s32, _fdnum), false)
 
+static inline void *_uobj_get_obj_read(struct ib_uobject *uobj)
+{
 	if (IS_ERR(uobj))
 		return NULL;
 	return uobj->object;
 }
 #define uobj_get_obj_read(_object, _type, _id, _ufile)                         \
-	((struct ib_##_object *)_uobj_get_obj_read(uobj_get_type(_type), _id,  \
-						   _ufile))
+	((struct ib_##_object *)_uobj_get_obj_read(                            \
+		uobj_get_read(_type, _id, _ufile)))
 
 #define uobj_get_write(_type, _id, _ufile)                                     \
-	__uobj_get(uobj_get_type(_type), true, _ufile, _id)
+	rdma_lookup_get_uobject(uobj_get_type(_type), _ufile,                  \
+				_uobj_check_id(_id), true)
 
-int __uobj_perform_destroy(const struct uverbs_obj_type *type, int id,
+int __uobj_perform_destroy(const struct uverbs_obj_type *type, u32 id,
 			   struct ib_uverbs_file *ufile, int success_res);
 #define uobj_perform_destroy(_type, _id, _ufile, _success_res)                 \
-	__uobj_perform_destroy(uobj_get_type(_type), _id, _ufile, _success_res)
+	__uobj_perform_destroy(uobj_get_type(_type), _uobj_check_id(_id),      \
+			       _ufile, _success_res)
 
 static inline void uobj_put_read(struct ib_uobject *uobj)
 {

include/rdma/uverbs_types.h

@@ -77,7 +77,7 @@ struct uverbs_obj_type_class {
 	void (*alloc_abort)(struct ib_uobject *uobj);
 
 	struct ib_uobject *(*lookup_get)(const struct uverbs_obj_type *type,
-					 struct ib_uverbs_file *ufile, int id,
+					 struct ib_uverbs_file *ufile, s64 id,
 					 bool exclusive);
 	void (*lookup_put)(struct ib_uobject *uobj, bool exclusive);
 	/*
@@ -121,7 +121,7 @@ struct uverbs_obj_idr_type {
 
 struct ib_uobject *rdma_lookup_get_uobject(const struct uverbs_obj_type *type,
 					   struct ib_uverbs_file *ufile,
-					   int id, bool exclusive);
+					   s64 id, bool exclusive);
 void rdma_lookup_put_uobject(struct ib_uobject *uobj, bool exclusive);
 struct ib_uobject *rdma_alloc_begin_uobject(const struct uverbs_obj_type *type,
 					    struct ib_uverbs_file *ufile);

include/uapi/rdma/rdma_user_ioctl_cmds.h

@@ -62,7 +62,12 @@ struct ib_uverbs_attr {
 		} enum_data;
 		__u16 reserved;
 	} attr_data;
-	__aligned_u64 data;	/* ptr to command, inline data or idr/fd */
+	union {
+		/* Used by PTR_IN/OUT, ENUM_IN and IDR */
+		__aligned_u64 data;
+		/* Used by FD_IN and FD_OUT */
+		__s64 data_s64;
+	};
 };
 
 struct ib_uverbs_ioctl_hdr {