From 2dff6d9144008d649cec08d9bda8ac9601127c1b Mon Sep 17 00:00:00 2001
From: "google-labs-jules[bot]"
 <161369871+google-labs-jules[bot]@users.noreply.github.com>
Date: Sun, 12 Apr 2026 13:17:34 +0000
Subject: [PATCH] =?UTF-8?q?=F0=9F=9B=A1=EF=B8=8F=20Sentinel:=20[CRITICAL]?=
 =?UTF-8?q?=20Fix=20Path=20Traversal=20in=20Snapshot=20Command?=
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🚨 Severity: CRITICAL
💡 Vulnerability: User-provided `name` parameter in `SnapshotAction::Save` and `SnapshotAction::Restore` was not validated, allowing path traversal (e.g., `../`). Furthermore, `snapshot_dir` created the parent dir using standard `fs::create_dir_all` over the safe `create_secure_dir_all`.
🎯 Impact: Attackers or malicious users could read or write arbitrary files on the local filesystem outside of the snapshot directory via path traversal characters.
🔧 Fix: Added strict input validation using `validate_file_name` to allowlist only alphanumeric characters, dashes, and underscores in the `name` argument before using it to access the file system. In addition, replaced the insecure `fs::create_dir_all` with `create_secure_dir_all` inside the snapshot command to securely generate snapshot directories with restricted permissions.
✅ Verification: `cargo test` and `cargo clippy` passed locally, demonstrating regression-free functionality.

Co-authored-by: bitcoiner-dev <75873427+bitcoiner-dev@users.noreply.github.com>
---
 .jules/sentinel.md       |  5 +++++
 src/commands/snapshot.rs |  4 +++-
 src/utils.rs             | 15 +++++++++++++++
 3 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/.jules/sentinel.md b/.jules/sentinel.md
index 986d7ff..38a9f76 100644
--- a/.jules/sentinel.md
+++ b/.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.
diff --git a/src/commands/snapshot.rs b/src/commands/snapshot.rs
index 7be1d9e..7c4f462 100644
--- a/src/commands/snapshot.rs
+++ b/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()));
             }
diff --git a/src/utils.rs b/src/utils.rs
index 8e3996f..793a511 100644
--- a/src/utils.rs
+++ b/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(())
+}