fix(#274): Add input validation to prevent command injection in git operations

Implemented strict whitelist-based validation for git branch names and
repository URLs to prevent command injection vulnerabilities in worktree
operations.

Security fixes:
- Created git-validation.util.ts with whitelist validation functions
- Added custom DTO validators for branch names and repository URLs
- Applied defense-in-depth validation in WorktreeManagerService
- Comprehensive test coverage (31 tests) for all validation scenarios

Validation rules:
- Branch names: alphanumeric + hyphens + underscores + slashes + dots only
- Repository URLs: https://, http://, ssh://, git:// protocols only
- Blocks: option injection (--), command substitution ($(), ``), shell operators
- Prevents: SSRF attacks (localhost, internal networks), credential injection

Defense layers:
1. DTO validation (first line of defense at API boundary)
2. Service-level validation (defense-in-depth before git operations)

Fixes #274

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

apps/orchestrator/src/git/git-validation.util.ts

@@ -0,0 +1,174 @@
+/**
+ * Git Input Validation Utility
+ *
+ * Provides strict validation for git references (branch names, repository URLs)
+ * to prevent command injection vulnerabilities.
+ *
+ * Security: Whitelist-based approach - only allow known-safe characters.
+ */
+
+import { BadRequestException } from "@nestjs/common";
+
+/**
+ * Validates a git branch name for safety
+ *
+ * Allowed format: alphanumeric, hyphens, underscores, forward slashes
+ * Examples: "main", "feature/add-login", "fix/bug_123"
+ *
+ * Rejected: Special characters that could be interpreted as git syntax
+ * Examples: "--option", "$(command)", ";malicious", "`command`"
+ *
+ * @param branchName - The branch name to validate
+ * @throws BadRequestException if branch name is invalid
+ */
+export function validateBranchName(branchName: string): void {
+  // Check for empty or whitespace-only
+  if (!branchName || branchName.trim().length === 0) {
+    throw new BadRequestException("Branch name cannot be empty");
+  }
+
+  // Check length (git has a 255 char limit for ref names)
+  if (branchName.length > 255) {
+    throw new BadRequestException("Branch name exceeds maximum length (255 characters)");
+  }
+
+  // Whitelist: only allow alphanumeric, hyphens, underscores, forward slashes, dots
+  // This prevents all forms of command injection
+  const safePattern = /^[a-zA-Z0-9/_.-]+$/;
+  if (!safePattern.test(branchName)) {
+    throw new BadRequestException(
+      `Branch name contains invalid characters. Only alphanumeric, hyphens, underscores, slashes, and dots are allowed.`
+    );
+  }
+
+  // Prevent git option injection (branch names starting with -)
+  if (branchName.startsWith("-")) {
+    throw new BadRequestException(
+      "Branch name cannot start with a hyphen (prevents option injection)"
+    );
+  }
+
+  // Prevent double dots (used for range specifications in git)
+  if (branchName.includes("..")) {
+    throw new BadRequestException("Branch name cannot contain consecutive dots (..)");
+  }
+
+  // Prevent path traversal patterns
+  if (branchName.includes("/../") || branchName.startsWith("../") || branchName.endsWith("/..")) {
+    throw new BadRequestException("Branch name cannot contain path traversal patterns");
+  }
+
+  // Prevent ending with .lock (reserved by git)
+  if (branchName.endsWith(".lock")) {
+    throw new BadRequestException("Branch name cannot end with .lock (reserved by git)");
+  }
+
+  // Prevent control characters
+  // eslint-disable-next-line no-control-regex
+  if (/[\x00-\x1F\x7F]/.test(branchName)) {
+    throw new BadRequestException("Branch name cannot contain control characters");
+  }
+}
+
+/**
+ * Validates a git repository URL for safety
+ *
+ * Allowed protocols: https, http (dev only), ssh (git@)
+ * Prevents: file://, javascript:, data:, and other dangerous protocols
+ *
+ * @param repositoryUrl - The repository URL to validate
+ * @throws BadRequestException if URL is invalid or uses dangerous protocol
+ */
+export function validateRepositoryUrl(repositoryUrl: string): void {
+  // Check for empty or whitespace-only
+  if (!repositoryUrl || repositoryUrl.trim().length === 0) {
+    throw new BadRequestException("Repository URL cannot be empty");
+  }
+
+  // Check length (reasonable limit for URLs)
+  if (repositoryUrl.length > 2000) {
+    throw new BadRequestException("Repository URL exceeds maximum length (2000 characters)");
+  }
+
+  // Remove whitespace
+  const url = repositoryUrl.trim();
+
+  // Whitelist allowed protocols
+  const httpsPattern = /^https:\/\//i;
+  const httpPattern = /^http:\/\//i; // Only for development
+  const sshGitPattern = /^git@[a-zA-Z0-9.-]+:/; // git@host:repo format
+  const sshUrlPattern = /^ssh:\/\/git@[a-zA-Z0-9.-]+(\/|:)/; // ssh://git@host/repo or ssh://git@host:repo
+
+  if (
+    !httpsPattern.test(url) &&
+    !httpPattern.test(url) &&
+    !sshGitPattern.test(url) &&
+    !sshUrlPattern.test(url) &&
+    !url.startsWith("git://")
+  ) {
+    throw new BadRequestException(
+      "Repository URL must use https://, http://, ssh://, git://, or git@ protocol"
+    );
+  }
+
+  // Prevent dangerous protocols
+  const dangerousProtocols = [
+    "file://",
+    "javascript:",
+    "data:",
+    "vbscript:",
+    "about:",
+    "chrome:",
+    "view-source:",
+  ];
+
+  for (const dangerous of dangerousProtocols) {
+    if (url.toLowerCase().startsWith(dangerous)) {
+      throw new BadRequestException(
+        `Repository URL cannot use ${dangerous} protocol (security risk)`
+      );
+    }
+  }
+
+  // Prevent localhost/internal network access (SSRF protection)
+  const localhostPatterns = [
+    /https?:\/\/(localhost|127\.0\.0\.1|0\.0\.0\.0|::1)/i,
+    /https?:\/\/192\.168\./i,
+    /https?:\/\/10\./i,
+    /https?:\/\/172\.(1[6-9]|2\d|3[01])\./i,
+  ];
+
+  for (const pattern of localhostPatterns) {
+    if (pattern.test(url)) {
+      throw new BadRequestException(
+        "Repository URL cannot point to localhost or internal networks (SSRF protection)"
+      );
+    }
+  }
+
+  // Prevent credential injection in URL
+  if (url.includes("@") && !sshGitPattern.test(url) && !sshUrlPattern.test(url)) {
+    // Extract the part before @ to check if it looks like credentials
+    const beforeAt = url.split("@")[0];
+    if (beforeAt.includes("://") && beforeAt.split("://")[1].includes(":")) {
+      throw new BadRequestException("Repository URL cannot contain embedded credentials");
+    }
+  }
+
+  // Prevent control characters and dangerous characters in URL
+  // eslint-disable-next-line no-control-regex
+  if (/[\x00-\x1F\x7F`$;|&]/.test(url)) {
+    throw new BadRequestException("Repository URL contains invalid or dangerous characters");
+  }
+}
+
+/**
+ * Validates a complete agent spawn context
+ *
+ * @param context - The spawn context with repository and branch
+ * @throws BadRequestException if any field is invalid
+ */
+export function validateSpawnContext(context: { repository: string; branch: string }): void {
+  validateRepositoryUrl(context.repository);
+  validateBranchName(context.branch);
+}