From ba1c6a1303fa771da52a337b24147a1cf6ecce42 Mon Sep 17 00:00:00 2001
From: Jack Grigg <jack@electriccoin.co>
Date: Fri, 7 Feb 2025 06:39:54 +0000
Subject: [PATCH] zcash_client_backend: Allow disabling Tor directory
 permissions tightening

Closes zcash/librustzcash#1686.
---
 Cargo.lock                        |  1 +
 Cargo.toml                        |  1 +
 zcash_client_backend/CHANGELOG.md |  3 +++
 zcash_client_backend/Cargo.toml   |  2 ++
 zcash_client_backend/src/tor.rs   | 23 ++++++++++++++++++-----
 5 files changed, 25 insertions(+), 5 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index 2aa7cfa5c..b46413b71 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -6158,6 +6158,7 @@ dependencies = [
  "crossbeam-channel",
  "document-features",
  "dynosaur",
+ "fs-mistrust",
  "futures-util",
  "group",
  "gumdrop",
diff --git a/Cargo.toml b/Cargo.toml
index 270af3862..e4d5b363a 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -158,6 +158,7 @@ incrementalmerkletree-testing = "0.3"
 #   failure due to incompatible `libsqlite3-sys` versions.
 arti-client = { version = "0.23", default-features = false, features = ["compression", "rustls", "tokio"] }
 dynosaur = "0.1.1"
+fs-mistrust = "0.8"
 tokio = "1"
 tor-rtcompat = "0.23"
 tower = "0.4"
diff --git a/zcash_client_backend/CHANGELOG.md b/zcash_client_backend/CHANGELOG.md
index e14fce74d..5ab7e0a11 100644
--- a/zcash_client_backend/CHANGELOG.md
+++ b/zcash_client_backend/CHANGELOG.md
@@ -11,6 +11,9 @@ and this library adheres to Rust's notion of
 - MSRV is now 1.81.0.
 - Migrated to `bip32 =0.6.0-pre.1`, `nonempty 0.11`, `incrementalmerkletree 0.8`,
   `shardtree 0.6`.
+- `zcash_client_backend::tor`:
+  - `tor::Client::create` now takes an optional `with_permissions` argument for
+    configuring `fs_mistrust::Mistrust`.
 - `zcash_client_backend::wallet::Recipient` has changed:
   - The `Recipient::External` variant is now a structured variant.
   - The `Recipient::EphemeralTransparent` variant is now only available if
diff --git a/zcash_client_backend/Cargo.toml b/zcash_client_backend/Cargo.toml
index 25680760c..cfebc640e 100644
--- a/zcash_client_backend/Cargo.toml
+++ b/zcash_client_backend/Cargo.toml
@@ -120,6 +120,7 @@ crossbeam-channel.workspace = true
 rayon.workspace = true
 
 # - Tor
+fs-mistrust = { workspace = true, optional = true }
 tokio = { workspace = true, optional = true, features = ["fs"] }
 tor-rtcompat = { workspace = true, optional = true }
 tower = { workspace = true, optional = true }
@@ -201,6 +202,7 @@ sync = [
 tor = [
     "dep:arti-client",
     "dep:dynosaur",
+    "dep:fs-mistrust",
     "dep:futures-util",
     "dep:http-body-util",
     "dep:hyper",
diff --git a/zcash_client_backend/src/tor.rs b/zcash_client_backend/src/tor.rs
index 8c900ab5c..7c600e338 100644
--- a/zcash_client_backend/src/tor.rs
+++ b/zcash_client_backend/src/tor.rs
@@ -24,20 +24,33 @@ impl Client {
     /// Preserving the contents of this directory will speed up subsequent calls to
     /// `Client::create`.
     ///
+    /// If `with_permissions` is `None`, the default from [`arti_client`] will be used
+    /// (enable permissions checks unless the `ARTI_FS_DISABLE_PERMISSION_CHECKS` env
+    /// variable is set).
+    ///
     /// Returns an error if `tor_dir` does not exist, or if bootstrapping fails.
-    pub async fn create(tor_dir: &Path) -> Result<Self, Error> {
+    pub async fn create(
+        tor_dir: &Path,
+        with_permissions: Option<impl FnOnce(&mut fs_mistrust::MistrustBuilder)>,
+    ) -> Result<Self, Error> {
         let runtime = PreferredRuntime::current()?;
 
         if !tokio::fs::try_exists(tor_dir).await? {
             return Err(Error::MissingTorDirectory);
         }
 
-        let config = TorClientConfigBuilder::from_directories(
+        let mut config_builder = TorClientConfigBuilder::from_directories(
             tor_dir.join("arti-data"),
             tor_dir.join("arti-cache"),
-        )
-        .build()
-        .expect("all required fields initialized");
+        );
+
+        if let Some(f) = with_permissions {
+            f(config_builder.storage().permissions());
+        }
+
+        let config = config_builder
+            .build()
+            .expect("all required fields initialized");
 
         let client_builder = TorClient::with_runtime(runtime).config(config);