Race Condition Enabling Link Following and Time-of-check Time-of-use (TOCTOU)

The remove_dir_all crate is a Rust library that offers additional features over the Rust
standard library fs::remove_dir_all function.

It was possible to trick a privileged process doing a recursive delete in an
attacker controlled directory into deleting privileged files, on all operating systems.

For instance, consider deleting a tree called 'etc' in a parent directory
called 'p'. Between calling remove_dir_all("a") and remove_dir_all("a")
actually starting its work, the attacker can move 'p' to 'p-prime', and
replace 'p' with a symlink to '/'. Then the privileged process deletes 'p/etc'
which is actually /etc, and now your system is broken. There are some
mitigations for this exact scenario, such as CWD relative file lookup, but
they are not guaranteed - any code using absolute paths will not have that
protection in place.

The same attack could be performed at any point in the directory tree being
deleted: if 'a' contains a child directory called 'etc', attacking the
deletion by replacing 'a' with a link is possible.

The new code in this release mitigates the attack within the directory tree
being deleted by using file-handle relative operations: to open 'a/etc', the
path 'etc' relative to 'a' is opened, where 'a' is represented by a file
descriptor (Unix) or handle (Windows). With the exception of the entry points
into the directory deletion logic, this is robust against manipulation of the
directory hierarchy, and remove_dir_all will only delete files and directories
contained in the tree it is deleting.

The entry path however is a challenge - as described above, there are some
potential mitigations, but since using them must be done by the calling code,
it is hard to be confident about the security properties of the path based
interface.

The new extension trait RemoveDir provides an interface where it is much
harder to get it wrong.

somedir.remove_dir_contents("name-of-child").

Callers can then make their own security evaluation about how to securely get
a directory handle. That is still not particularly obvious, and we're going to
follow up with a helper of some sort (probably in the fs_at crate). Once
that is available, the path based entry points will get deprecated.

In the interim, processes that might run with elevated privileges should
figure out how to securely identify the directory they are going to delete, to
avoid the initial race. Pragmatically, other processes should be fine with the
path based entry points : this is the same interface std::fs::remove_dir_all
offers, and an unprivileged process running in an attacker controlled
directory can't do anything that the attacker can't already do.

See advisory page for additional details.

reject_remote_clients Configuration corruption

On Windows, configuring a named pipe server with pipe_mode will force ServerOptions::reject_remote_clients as false.

This drops any intended explicit configuration for the reject_remote_clients that may have been set as true previously.

The default setting of reject_remote_clients is normally true meaning the default is also overriden as false.

Workarounds

Ensure that pipe_mode is set first after initializing a ServerOptions. For example:

let mut opts = ServerOptions::new();
opts.pipe_mode(PipeMode::Message);
opts.reject_remote_clients(true);

See advisory page for additional details.

openssl X509VerifyParamRef::set_host buffer over-read

When this function was passed an empty string, openssl would attempt to call strlen on it, reading arbitrary memory until it reached a NUL byte.

See advisory page for additional details.

Resource exhaustion vulnerability in h2 may lead to Denial of Service (DoS)

If an attacker is able to flood the network with pairs of HEADERS/RST_STREAM frames, such that the h2 application is not able to accept them faster than the bytes are received, the pending accept queue can grow in memory usage. Being able to do this consistently can result in excessive memory use, and eventually trigger Out Of Memory.

This flaw is corrected in hyperium/h2#668, which restricts remote reset stream count by default.

See advisory page for additional details.

openssl X509Extension::new and X509Extension::new_nid null pointer dereference

These functions would crash when the context argument was None with certain extension types.

Thanks to David Benjamin (Google) for reporting this issue.

See advisory page for additional details.

openssl SubjectAlternativeName and ExtendedKeyUsage::other allow arbitrary file read

SubjectAlternativeName and ExtendedKeyUsage arguments were parsed using the OpenSSL
function X509V3_EXT_nconf. This function parses all input using an OpenSSL mini-language
which can perform arbitrary file reads.

Thanks to David Benjamin (Google) for reporting this issue.

See advisory page for additional details.

openssl X509NameBuilder::build returned object is not thread safe

OpenSSL has a modified bit that it can set on on X509_NAME objects. If this
bit is set then the object is not thread-safe even when it appears the code is
not modifying the value.

Thanks to David Benjamin (Google) for reporting this issue.

See advisory page for additional details.

Hi, and great content btw.

I've noticed that you don't use tags at all that allow people to see just the content that has changed for specific videos. For example, after watching the first video, I would like to see the code that you used and showed in that video. Unfortunately, after going to the github link here, I can only see the whole codebase created from ALL the videos. This makes it difficult to understand what is related to just starting up actix and yew (as seen in video 1) and what is for all the other content in later videos.

Using git tags would allow me to grab a specific version matching the video I am watching. It would also allow me to diff between versions to see what changed too.

Would it be possible to add tags that synchronise with the released videos on youtube? Thanks.

I get the error in the title when running make up. Ubuntu 22.04 LTS.

sudo apt install docker
...
~/repos/yew-actix-template$ make up
docker compose -f docker/docker-compose.yaml up
unknown shorthand flag: 'f' in -f
See 'docker --help'.