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>

1 files changed, 2 insertions, 2 deletions

diff --git a/include/rdma/uverbs_types.h b/include/rdma/uverbs_types.h
index e2fc9db466d3..2f50cc6def3c 100644
--- a/include/rdma/uverbs_types.h
+++ b/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);