UnixListener::bind with abstract unix socket path has an extra \0 prefix

[zonyitoo]

Version

v1.40.0

Platform
Linux VM-66-53-centos 5.4.241-1-tlinux4-0017.12 #1 SMP Fri Aug 2 14:51:21 CST 2024 x86_64 x86_64 x86_64 GNU/Linux

Description

Example code:

let abstract_path = "\0/tmp/mesh/business/mmmeshexample";
let listener = UnixListener::bind(abstract_path).unwrap();

It should create a socket listening to @/tmp/mesh/business/mmmeshexample, but with netstat -alpn, we can see:

unix  2      [ ACC ]     STREAM     LISTENING     2483935  229872/target/debug  @@/tmp/mesh/business/mmmeshexampl

Obviously the sun_path that passed to bind() syscall has an extra \0 prefix and the length of the whole sockaddr_un was missing 1 byte.

This bug couldn't be reproduced in v1.26.0. After looked deep into the code, I found the bug was quite obvious:

tokio/tokio/src/net/unix/listener.rs

Lines 83 to 84 in 9116999

	if os_str_bytes.starts_with(b"\0") {
	StdSocketAddr::from_abstract_name(os_str_bytes)?

It checks the path from parameter, if it has a prefix \0 then calls StdSocketAddr::from_abstract_name.

https://github.com/rust-lang/rust/blob/5a2dd7d4f3210629e65879aeecbe643ba3b86bb4/library/std/src/os/unix/net/addr.rs#L269-L293

SocketAddr::from_abstract_name assumes the name in parameter doesn't have a prefix \0.

The same bug was also in UnixStream::connect:

tokio/tokio/src/net/unix/stream.rs

Lines 79 to 80 in d621359

	if os_str_bytes.starts_with(b"\0") {
	StdSocketAddr::from_abstract_name(os_str_bytes)?

[zonyitoo]

The bug was introduced from this commit: b2ea40b by @mox692 , please consider submit a fix.

One possible and straight forward solution:

    StdSocketAddr::from_abstract_name(&os_str_bytes[1..])?

[mox692]

Thanks for the report, I'll submit a fix for this soon.