🛡️ Sentinel: [CRITICAL] Fix path traversal in snapshot commands

.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.
+
+## 2024-04-15 - Path Traversal in Snapshot Commands
+**Vulnerability:** The snapshot `save` and `restore` commands allowed path traversal because the user-provided snapshot `name` was joined directly to the base snapshot directory path without validation. This allowed writing or reading files outside of the intended directory using `../` sequences in the name.
+**Learning:** File paths constructed using user input must be strictly validated to prevent path traversal attacks, especially in CLI tools where user input is directly used for file operations.
+**Prevention:** Implement and use a strict allowlist validation function (e.g., `validate_file_name`) that only permits alphanumeric characters, dashes, and underscores for any user-provided string used as a filename.

src/commands/snapshot.rs

@@ -12,6 +12,7 @@ pub async fn run(cli: &Cli, args: &SnapshotArgs) -> Result<CommandOutput, AppErr
 
     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()));
+    }
+    for c in name.chars() {
+        if !c.is_ascii_alphanumeric() && c != '_' && c != '-' {
+            return Err(AppError::Invalid(format!(
+                "invalid character in file name: '{}'",
+                c
+            )));
+        }
+    }
+    Ok(())
+}