RDMA: Add ib_copy_validate_udata_in()

Add a new function to consolidate the required compatibility pattern for
driver data of checking against a minimum size, and checking for unknown
trailing bytes to be zero into a function.

This new function uses the faster copy_struct_from_user() instead of
trying to directly check for zero.

Incorporate the common ibdev_dbg() logging directly into the error paths
of the helper.

Link: https://patch.msgid.link/r/3-v3-bd56dd443069+49-bnxt_re_uapi_jgg@nvidia.com
Tested-by: Sriharsha Basavapatna <sriharsha.basavapatna@broadcom.com>
Acked-by: Sriharsha Basavapatna <sriharsha.basavapatna@broadcom.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

drivers/infiniband/core/rdma_core.h

@@ -151,6 +151,9 @@ void uapi_compute_bundle_size(struct uverbs_api_ioctl_method *method_elm,
 			      unsigned int num_attrs);
 void uverbs_user_mmap_disassociate(struct ib_uverbs_file *ufile);
 
+typedef int (*uverbs_api_ioctl_handler_fn)(struct uverbs_attr_bundle *attrs);
+uverbs_api_ioctl_handler_fn uverbs_get_handler_fn(struct ib_udata *udata);
+
 extern const struct uapi_definition uverbs_def_obj_async_fd[];
 extern const struct uapi_definition uverbs_def_obj_counters[];
 extern const struct uapi_definition uverbs_def_obj_cq[];

drivers/infiniband/core/uverbs_ioctl.c

@@ -70,6 +70,19 @@ struct bundle_priv {
 	u64 internal_buffer[32];
 };
 
+uverbs_api_ioctl_handler_fn uverbs_get_handler_fn(struct ib_udata *udata)
+{
+	struct uverbs_attr_bundle *bundle =
+		rdma_udata_to_uverbs_attr_bundle(udata);
+	struct bundle_priv *pbundle =
+		container_of(&bundle->hdr, struct bundle_priv, bundle);
+
+	lockdep_assert_held(&bundle->ufile->device->disassociate_srcu);
+
+	return srcu_dereference(pbundle->method_elm->handler,
+				&bundle->ufile->device->disassociate_srcu);
+}
+
 /*
  * Each method has an absolute minimum amount of memory it needs to allocate,
  * precompute that amount and determine if the onstack memory can be used or
@@ -847,3 +860,41 @@ void uverbs_finalize_uobj_create(const struct uverbs_attr_bundle *bundle,
 		  pbundle->uobj_hw_obj_valid);
 }
 EXPORT_SYMBOL(uverbs_finalize_uobj_create);
+
+int _ib_copy_validate_udata_in(struct ib_udata *udata, void *req,
+			       size_t kernel_size, size_t minimum_size)
+{
+	int err;
+
+	if (udata->inlen < minimum_size) {
+		ibdev_dbg(
+			rdma_udata_to_dev(udata),
+			"System call driver input udata too small (%zu < %zu) for ioctl %ps called by %pSR\n",
+			udata->inlen, minimum_size,
+			uverbs_get_handler_fn(udata),
+			__builtin_return_address(0));
+		return -EINVAL;
+	}
+
+	err = copy_struct_from_user(req, kernel_size, udata->inbuf,
+				    udata->inlen);
+	if (err) {
+		if (err == -E2BIG) {
+			ibdev_dbg(
+				rdma_udata_to_dev(udata),
+				"System call driver input udata not zero from %zu -> %zu for ioctl %ps called by %pSR\n",
+				minimum_size, udata->inlen,
+				uverbs_get_handler_fn(udata),
+				__builtin_return_address(0));
+			return -EOPNOTSUPP;
+		}
+		ibdev_dbg(
+			rdma_udata_to_dev(udata),
+			"System call driver input udata EFAULT for ioctl %ps called by %pSR\n",
+			uverbs_get_handler_fn(udata),
+			__builtin_return_address(0));
+		return err;
+	}
+	return 0;
+}
+EXPORT_SYMBOL(_ib_copy_validate_udata_in);

include/rdma/uverbs_ioctl.h

@@ -897,6 +897,9 @@ int _uverbs_get_const_unsigned(u64 *to,
 			       size_t idx, u64 upper_bound, u64 *def_val);
 int uverbs_copy_to_struct_or_zero(const struct uverbs_attr_bundle *bundle,
 				  size_t idx, const void *from, size_t size);
+
+int _ib_copy_validate_udata_in(struct ib_udata *udata, void *req,
+			       size_t kernel_size, size_t minimum_size);
 #else
 static inline int
 uverbs_get_flags64(u64 *to, const struct uverbs_attr_bundle *attrs_bundle,
@@ -953,6 +956,14 @@ _uverbs_get_const_unsigned(u64 *to,
 {
 	return -EINVAL;
 }
+
+static inline int _ib_copy_validate_udata_in(struct ib_udata *udata, void *req,
+					     size_t kernel_size,
+					     size_t minimum_size)
+{
+	return -EINVAL;
+}
+
 #endif
 
 #define uverbs_get_const_signed(_to, _attrs_bundle, _idx)                      \
@@ -1018,4 +1029,19 @@ uverbs_get_raw_fd(int *to, const struct uverbs_attr_bundle *attrs_bundle,
 	return uverbs_get_const_signed(to, attrs_bundle, idx);
 }
 
+/**
+ * ib_copy_validate_udata_in - Copy and validate that the request structure is
+ *                             compatible with this kernel
+ * @_udata: The system calls ib_udata struct
+ * @_req: The name of an on-stack structure that holds the driver data
+ * @_end_member: The member in the struct that is the original end of struct
+ *               from the first kernel to introduce it.
+ *
+ * Check that the udata input request struct is properly formed for this kernel.
+ * Then copy it into req
+ */
+#define ib_copy_validate_udata_in(_udata, _req, _end_member)      \
+	_ib_copy_validate_udata_in(_udata, &(_req), sizeof(_req), \
+				   offsetofend(typeof(_req), _end_member))
+
 #endif