Opened 11 months ago

Closed 9 months ago

Last modified 3 weeks ago

#21862 closed defect (fixed)

Make rust code in ESR 52 proxy safe

Reported by: gk Owned by: tbb-team
Priority: Medium Milestone:
Component: Applications/Tor Browser Version:
Severity: Normal Keywords: ff52-esr, tbb-7.0-must, TorBrowserTeam201706R
Cc: Actual Points:
Parent ID: Points:
Reviewer: Sponsor: Sponsor4


Even though we don't use any Rust in ESR 52 we should get rid of proxy bypassing calls for safety and to remind us for later:

third_party/rust/url/src/ has a to_socket_addrs and ToSocketAddrs methods.

Child Tickets

Change History (14)

comment:1 Changed 11 months ago by cypherpunks

Are you compiling with --enable-rust so that those calls are available?

comment:2 Changed 11 months ago by gk


comment:3 Changed 11 months ago by cypherpunks

Then what rust code is in ESR52?

comment:4 Changed 10 months ago by gk

Keywords: TorBrowserTeam201705 added; TorBrowserTeam201704 removed

Moving our tickets to May 2017.

comment:5 Changed 9 months ago by gk

Keywords: tbb-7.0-must added; tbb-7.0-must-alpha removed

We are beyond the alpha testing. Moving tickets for tbb-7.0-must.

comment:6 Changed 9 months ago by gk

Keywords: TorBrowserTeam201705R added; TorBrowserTeam201705 removed
Status: newneeds_review

comment:7 Changed 9 months ago by gk

Keywords: TorBrowserTeam201706R added; TorBrowserTeam201705R removed

Moving review tickets to 201706

comment:8 Changed 9 months ago by mcs

I don't read or write Rust, but your changes look okay. Maybe we should ask a Rust person to look at them? Certainly your patch is good enough to serve as a reminder that we need to look at the Rust code more closely once we start compiling it.

comment:9 Changed 9 months ago by arthuredelstein

I don't know rust either, but I was curious what happens if these functions are ripped out. Is any code calling them?

I tried building with ac_add_options --enable-rust in the mozconfig file and I got the follow error message:

 2:45.75 error: the listed checksum of `/home/arthur/tor-browser/third_party/rust/url/src/` has changed:
 2:45.75 expected: c3542aabc733f76a3b9c7d24b5c41e60e9eb84d2712660611300d1de0e7c2072
 2:45.75 actual:   3abae55faf84f05be573d6275fa49ca2e61a4a95e3717a9059e3971b5d53101a
 2:45.75 directory sources are not intended to be edited, if modifications are required then it is recommended that [replace] is used with a forked copy of the source
 2:45.76 /home/arthur/tor-browser/config/ recipe for target 'force-cargo-build' failed
 2:45.76 make[5]: *** [force-cargo-build] Error 101
 2:45.76 /home/arthur/tor-browser/config/ recipe for target 'toolkit/library/rust/target' failed
 2:45.76 make[4]: *** [toolkit/library/rust/target] Error 2
 2:45.76 make[4]: *** Waiting for unfinished jobs....

The "expected" hash (c3542aab...) is located in third_party/rust/url/.cargo-checksum.json. The README in the same directory says this code is a

URL library for Rust, based on the [URL Standard](

So it looks to me like this is patching a "third-party library", whereas we should probably be ripping out something considered to be "first-party" gecko code.

Another option might be just to remove the whole third-party directory or even all rust files from the source code.

comment:10 in reply to:  9 Changed 9 months ago by gk

Resolution: fixed
Status: needs_reviewclosed

Replying to arthuredelstein:

So it looks to me like this is patching a "third-party library", whereas we should probably be ripping out something considered to be "first-party" gecko code.

Another option might be just to remove the whole third-party directory or even all rust files from the source code.

I think that is a good reminder of what we need to think about once building Rust parts is mandatory as this is different from the way we handled a lot of our proxy-bypass-(in-depth)-defenses so far. I think just for the sake of having those calls out of esr52 the current approach still seems to be sufficient. And if you can't get the stuff even compiled right now, even better. :) Thus, I take it as-is.

Applied to tor-browser-52.1.1esr-7.0-1 and tor-browser-52.1.0-7.0-2 (commit 78aa6185cd8d1d11e09495f6e4dc5cbc19e80cba and 88c25c56d96f8fc0801359358d808f0d0e7d4b93) with a changed commit message pointing out that we probably need a more elaborate approach once we compile with Rust enabled.

comment:11 Changed 8 months ago by

In the next ESR (and already in the current release), --enable-rust will not exist.

When we say "third party" code it means vendored dependencies necessary for building Firefox that are not directly maintained in the mozilla-central repo. This is not something that can/should be ripped out. Currently, the third_party directory is only used for vendored Rust dependencies, however other vendored code may move there in the future.

In fact, rust-url is maintained by Servo, which is a Mozilla project. However, there are other crates under third_party which are not maintained by Mozilla. We intend to do some auditing before shipping. The currently shipping crates are all maintained by the Servo or Rust projects.

Currently (as of a recent nightly), the Rust code in mozilla-central consists of:

  • The mp4 parser. Enabled by default. Should not hit the network.
  • Stylo (enabled recently); servo's style system in Firefox. Built by default, preffed off , planned to be preffed on on 57. Can be disabled; is a large chunk of code. May become mandatory a few release cycles after 57. This should not hit the network on its own, we thread through Gecko networking code.
  • Webrender. Built by default, preffed off. Should not hit the network.
  • encoding-rs. I believe this is built by default and preffed on, but I am unsure. Should not hit the network.
  • rust-url for parsing, serialization, and manipulation of URLs. built by default, preffed off. This is a currently-stalled experiment which won't be enabled before we make it work well with everything. While this itself shouldn't be hitting the network (it's only for dealing with the URL data, not making requests), it will be audited more rigorously before being enabled (right now it's just there for experimentation)
  • We unconditionally use rust-url's IPV6 parsing code as of . This code shouldn't hit the network.

The call to getaddrinfo mentioned here exists because there is a ToSocketAddrs implementation for URL; an implementation which is never invoked.

However, we can probably add a build time option to remove them.

All the Rust code in Firefox gets built into $objdir/toolkit/library/$target/(debug or release)/libgkrust.a, so inspecting that binary may be useful in ensuring that getaddrinfo is never called. Currently none of the Rust code being used should be calling it. However, the standard library does include a call to getaddrinfo that goes unused, which still turns up in that file -- I'm not sure how to differentiate between used and unused here -- I tried creating a test Rust staticlib that didn't do anything and even with -Clto the final staticlib still had an unlinked getaddrinfo symbol. If y'all know the correct linker args and nm / objdump invocation to use, let me know and I'll run it on my local all-rust-enabled Firefox build.

Let me know if you need more info!

comment:12 Changed 7 months ago by gk

Thanks, that's really helpful. For now we are good. We'll take a closer look at it during the transition to esr59 and will get back to you in case we need more info.

comment:13 Changed 4 weeks ago by arthuredelstein

Keywords: tbb-no-uplift added

comment:14 Changed 3 weeks ago by arthuredelstein

Keywords: tbb-no-uplift removed
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