[LibOS] `bind` Unix socket, `addrlen` parameter checking is different from Linux, and causes error in Python

[llly]

Description of the problem

Graphene shim_do_bind function return EINVAL for "addrlen is wrong" when addrlen is not same as sizeof(struct sockaddr_un), which is 110. https://github.com/oscarlab/graphene/blob/20156c6e23ea6570614197a97daf77dcd764153b/LibOS/shim/src/sys/shim_socket.c#L467-L469 But smaller size can work on Linux.

Steps to reproduce

Copy example from man bind and change

 if (bind(sfd, (struct sockaddr *) &my_addr,  sizeof(struct sockaddr_un)) == -1)

to

 if (bind(sfd, (struct sockaddr *) &my_addr, strlen(MY_SOCK_PATH) + 4) == -1)

Compile and create Graphene manifest.

Expected results

App with and without Graphene both can run without error.

Actual results

App without Graphene can run without error. App with Graphene returns bind: Invalid argument.

Additional information

Bind Unix socket using Python can work on Linux, but fails with Graphene. https://hg.python.org/cpython/file/3.6/Modules/socketmodule.c#l2700

res = bind(s->sock_fd, SAS2SA(&addrbuf), addrlen);

addrlen is calculated at https://hg.python.org/cpython/file/3.6/Modules/socketmodule.c#l1581

*len_ret = path.len + offsetof(struct sockaddr_un, sun_path);

[dimakuv]

@llly So just replacing https://github.com/oscarlab/graphene/blob/20156c6e23ea6570614197a97daf77dcd764153b/LibOS/shim/src/sys/shim_socket.c#L468

with if (addrlen > sizeof(struct sockaddr_un)) should work?

[llly]

Yes. I think so.

[dimakuv]

Please try https://github.com/oscarlab/graphene/pull/2620