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>

1 files changed, 26 insertions, 0 deletions

diff --git a/include/rdma/uverbs_ioctl.h b/include/rdma/uverbs_ioctl.h
index bb86d8ae8a83..505492443c36 100644
--- a/include/rdma/uverbs_ioctl.h
+++ b/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