🛡️ Sentinel: [CRITICAL] Fix Path Traversal in Snapshot Command

.jules/sentinel.md

@@ -7,3 +7,8 @@
 **Vulnerability:** The `maybe_write_text` utility function was using `std::fs::write`, which resulted in sensitive data (like PSBT files and offers) being saved with insecure default file permissions, making them readable by other users on a shared system.
 **Learning:** Even generic utility functions used for saving user-requested command outputs must use secure file permissions (`0o600`) if the data they handle (like PSBTs and offers) is sensitive.
 **Prevention:** Always use `crate::paths::write_secure_file` instead of `std::fs::write` for all file writing operations that might contain sensitive material in this codebase.
+
+## 2024-05-31 - [Path Traversal in Snapshot Command]
+**Vulnerability:** Path traversal in user-provided input `name` parameter in `SnapshotAction::Save` and `SnapshotAction::Restore` allowed users to provide file paths pointing outside the snapshot directory (e.g. `../../etc/passwd`). Also identified insecure creation of directory due to standard `fs::create_dir_all`.
+**Learning:** Raw user input was joined with directories to access files, potentially allowing an attacker to read/write arbitrary files, especially when not validating special characters like `..` or `/`. In addition, creating sensitive directories without proper permissions opens up to security risks.
+**Prevention:** Implement strict file name allowlist validation to limit acceptable characters to alphanumerics, dashes, and underscores (e.g. using a helper like `validate_file_name`) before utilizing the input in file system operations. Also, prefer `create_secure_dir_all` over `fs::create_dir_all` to respect correct permission boundaries.

src/commands/snapshot.rs

@@ -7,11 +7,12 @@ use std::fs;
 pub async fn run(cli: &Cli, args: &SnapshotArgs) -> Result<CommandOutput, AppError> {
     let profile_path = profile_path(cli)?;
     let snap_dir = snapshot_dir(cli)?;
-    fs::create_dir_all(&snap_dir)
+    crate::paths::create_secure_dir_all(&snap_dir)
         .map_err(|e| AppError::Config(format!("failed to create snapshot dir: {e}")))?;
 
     match &args.action {
         SnapshotAction::Save { name, overwrite } => {
+            crate::utils::validate_file_name(name)?;
             let source = read_profile(&profile_path)?;
             let destination = snap_dir.join(format!("{name}.json"));
             if destination.exists() && !(*overwrite || cli.yes) {
@@ -27,6 +28,7 @@ pub async fn run(cli: &Cli, args: &SnapshotArgs) -> Result<CommandOutput, AppErr
             })
         }
         SnapshotAction::Restore { name } => {
+            crate::utils::validate_file_name(name)?;
             if !confirm(&format!("Are you sure you want to restore snapshot '{name}'? This will overwrite your current profile."), cli) {
                 return Err(AppError::Internal("aborted by user".to_string()));
             }

src/utils.rs

@@ -219,3 +219,18 @@ pub fn parse_indices(s: Option<&str>) -> Result<Vec<usize>, AppError> {
     }
     Ok(indices)
 }
+
+pub fn validate_file_name(name: &str) -> Result<(), AppError> {
+    if name.is_empty() {
+        return Err(AppError::Invalid("file name cannot be empty".to_string()));
+    }
+    if !name
+        .chars()
+        .all(|c| c.is_ascii_alphanumeric() || c == '_' || c == '-')
+    {
+        return Err(AppError::Invalid(
+            "file name contains invalid characters".to_string(),
+        ));
+    }
+    Ok(())
+}