From 607d58df84337139014928fa99a0970767a9aca0 Mon Sep 17 00:00:00 2001
From: Paul Campbell <pcampbell@kemitix.net>
Date: Sun, 28 Apr 2024 14:58:55 +0100
Subject: [PATCH] feat(fs): properly validates paths are within base directory

---
 Cargo.toml      |  1 +
 src/fs/real.rs  | 17 +++++++++++++++--
 src/tests/fs.rs | 41 +++++++++++++++++++++++++++--------------
 3 files changed, 43 insertions(+), 16 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index dd177dc..feb7876 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -31,6 +31,7 @@ thiserror = "1.0"
 
 # fs
 tempfile = "3.10"
+path-clean = "1.0"
 
 # error handling
 derive_more = { version = "1.0.0-beta.6", features = ["from", "display"] }
diff --git a/src/fs/real.rs b/src/fs/real.rs
index d91fc9d..a975e2f 100644
--- a/src/fs/real.rs
+++ b/src/fs/real.rs
@@ -57,12 +57,25 @@ impl super::FileSystemLike for RealFileSystem {
 
 impl RealFileSystem {
     fn validate(&self, path: &Path) -> super::Result<()> {
-        if !path.starts_with(&self.base) {
+        let canon = self.clean_path(path)?;
+        if !canon.starts_with(&self.base) {
             return Err(super::Error::PathTraversal {
                 base: self.base.clone(),
-                path: path.to_path_buf(),
+                path: canon.to_path_buf(),
             });
         }
         Ok(())
     }
+
+    fn clean_path(&self, path: &Path) -> super::Result<PathBuf> {
+        // let path = path.as_ref();
+        use path_clean::PathClean;
+        let abs_path = if path.is_absolute() {
+            path.to_path_buf()
+        } else {
+            std::env::current_dir()?.join(path)
+        }
+        .clean();
+        Ok(abs_path)
+    }
 }
diff --git a/src/tests/fs.rs b/src/tests/fs.rs
index 5123ab5..aa358b8 100644
--- a/src/tests/fs.rs
+++ b/src/tests/fs.rs
@@ -1,22 +1,35 @@
-use std::path::PathBuf;
+use assert2::let_assert;
 
 use crate::fs;
 
-type TestResult = Result<(), crate::fs::Error>;
+type TestResult = Result<(), fs::Error>;
+
+#[test]
+fn path_of_validate_fails_path_traversal() -> TestResult {
+    let fs = fs::temp()?;
+
+    let_assert!(Err(fs::Error::PathTraversal { base, path: _path }) = fs.path_of("..".into()));
+    assert_eq!(base, fs.base());
+
+    Ok(())
+}
 
 #[test]
 fn write_read_file_exists() -> TestResult {
     let fs = fs::temp()?;
-    let pathbuf: PathBuf = fs.path_of("foo".into())?;
+    let pathbuf = fs.base().join("foo");
 
-    fs.file_write(&pathbuf, "content")?;
-    let c = fs.file_read_to_string(&pathbuf)?;
+    let_assert!(Ok(_) = fs.file_write(&pathbuf, "content"));
+    let_assert!(
+        Ok(c) = fs.file_read_to_string(&pathbuf),
+        "file_read_to_string"
+    );
     assert_eq!(c, "content");
 
-    let exists = fs.path_exists(&pathbuf)?;
+    let_assert!(Ok(exists) = fs.path_exists(&pathbuf));
     assert!(exists);
 
-    let is_file = fs.path_is_file(&pathbuf)?;
+    let_assert!(Ok(is_file) = fs.path_is_file(&pathbuf));
     assert!(is_file);
 
     Ok(())
@@ -25,14 +38,14 @@ fn write_read_file_exists() -> TestResult {
 #[test]
 fn create_dir_should_create_a_dir() -> TestResult {
     let fs = fs::temp()?;
-    let pathbuf = fs.path_of("subdir".into())?;
+    let pathbuf = fs.base().join("subdir");
 
-    fs.dir_create(&pathbuf)?;
+    let_assert!(Ok(_) = fs.dir_create(&pathbuf));
 
-    let exists = fs.path_exists(&pathbuf)?;
+    let_assert!(Ok(exists) = fs.path_exists(&pathbuf));
     assert!(exists);
 
-    let is_dir = fs.path_is_dir(&pathbuf)?;
+    let_assert!(Ok(is_dir) = fs.path_is_dir(&pathbuf));
     assert!(is_dir);
 
     Ok(())
@@ -43,12 +56,12 @@ fn create_dir_all_should_create_a_dir() -> TestResult {
     let fs = fs::temp()?;
     let pathbuf = fs.base().join("subdir").join("child");
 
-    fs.dir_create_all(&pathbuf)?;
+    let_assert!(Ok(_) = fs.dir_create_all(&pathbuf));
 
-    let exists = fs.path_exists(&pathbuf)?;
+    let_assert!(Ok(exists) = fs.path_exists(&pathbuf));
     assert!(exists, "path exists");
 
-    let is_dir = fs.path_is_dir(&pathbuf)?;
+    let_assert!(Ok(is_dir) = fs.path_is_dir(&pathbuf));
     assert!(is_dir, "path is a directory");
 
     Ok(())