4.14-stable review patch. If anyone has any objections, please let me know.
------------------
From: Jason Gunthorpe jgg@mellanox.com
[ Upstream commit 3624a8f02568f08aef299d3b117f2226f621177d ]
Returning EOPNOTSUPP is problematic because it can also be returned by the method function, and we use it in quite a few places in drivers these days.
Instead, dedicate EPROTONOSUPPORT to indicate that the ioctl framework is enabled but the requested object and method are not supported by the kernel. No other case will return this code, and it lets userspace know to fall back to write().
grep says we do not use it today in drivers/infiniband subsystem.
Signed-off-by: Jason Gunthorpe jgg@mellanox.com Reviewed-by: Matan Barak matanb@mellanox.com Signed-off-by: Doug Ledford dledford@redhat.com Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/infiniband/core/uverbs_ioctl.c | 19 +++++++++++++------ 1 file changed, 13 insertions(+), 6 deletions(-)
--- a/drivers/infiniband/core/uverbs_ioctl.c +++ b/drivers/infiniband/core/uverbs_ioctl.c @@ -245,16 +245,13 @@ static long ib_uverbs_cmd_verbs(struct i uintptr_t data[UVERBS_OPTIMIZE_USING_STACK_SZ / sizeof(uintptr_t)]; #endif
- if (hdr->reserved) - return -EINVAL; - object_spec = uverbs_get_object(ib_dev, hdr->object_id); if (!object_spec) - return -EOPNOTSUPP; + return -EPROTONOSUPPORT;
method_spec = uverbs_get_method(object_spec, hdr->method_id); if (!method_spec) - return -EOPNOTSUPP; + return -EPROTONOSUPPORT;
if ((method_spec->flags & UVERBS_ACTION_FLAG_CREATE_ROOT) ^ !file->ucontext) return -EINVAL; @@ -310,6 +307,16 @@ static long ib_uverbs_cmd_verbs(struct i
err = uverbs_handle_method(buf, ctx->uattrs, hdr->num_attrs, ib_dev, file, method_spec, ctx->uverbs_attr_bundle); + + /* + * EPROTONOSUPPORT is ONLY to be returned if the ioctl framework can + * not invoke the method because the request is not supported. No + * other cases should return this code. + */ + if (unlikely(err == -EPROTONOSUPPORT)) { + WARN_ON_ONCE(err == -EPROTONOSUPPORT); + err = -EINVAL; + } out: #ifdef UVERBS_OPTIMIZE_USING_STACK_SZ if (ctx_size > UVERBS_OPTIMIZE_USING_STACK_SZ) @@ -348,7 +355,7 @@ long ib_uverbs_ioctl(struct file *filp, }
if (hdr.reserved) { - err = -EOPNOTSUPP; + err = -EPROTONOSUPPORT; goto out; }