src: avoid copying string in fs_permission

PR-URL: #47746
Reviewed-By: Rafael Gonzaga <rafael.nunu@hotmail.com>
Reviewed-By: Daeyeon Jeong <daeyeon.dev@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Deokjin Kim <deokjin81.kim@gmail.com>
Reviewed-By: Darshan Sen <raisinten@gmail.com>

src/permission/fs_permission.cc

@@ -0,0 +1,180 @@
+#include "fs_permission.h"
+#include "base_object-inl.h"
+#include "util.h"
+#include "v8.h"
+
+#include <fcntl.h>
+#include <limits.h>
+#include <stdlib.h>
+#include <algorithm>
+#include <filesystem>
+#include <string>
+#include <vector>
+
+namespace {
+
+std::string WildcardIfDir(const std::string& res) noexcept {
+  uv_fs_t req;
+  int rc = uv_fs_stat(nullptr, &req, res.c_str(), nullptr);
+  if (rc == 0) {
+    const uv_stat_t* const s = static_cast<const uv_stat_t*>(req.ptr);
+    if (s->st_mode & S_IFDIR) {
+      // add wildcard when directory
+      if (res.back() == node::kPathSeparator) {
+        return res + "*";
+      }
+      return res + node::kPathSeparator + "*";
+    }
+  }
+  uv_fs_req_cleanup(&req);
+  return res;
+}
+
+void FreeRecursivelyNode(
+    node::permission::FSPermission::RadixTree::Node* node) {
+  if (node == nullptr) {
+    return;
+  }
+
+  if (node->children.size()) {
+    for (auto& c : node->children) {
+      FreeRecursivelyNode(c.second);
+    }
+  }
+
+  if (node->wildcard_child != nullptr) {
+    delete node->wildcard_child;
+  }
+  delete node;
+}
+
+bool is_tree_granted(node::permission::FSPermission::RadixTree* granted_tree,
+                     const std::string_view& param) {
+#ifdef _WIN32
+  // is UNC file path
+  if (param.rfind("\\\\", 0) == 0) {
+    // return lookup with normalized param
+    int starting_pos = 4;  // "\\?\"
+    if (param.rfind("\\\\?\\UNC\\") == 0) {
+      starting_pos += 4;  // "UNC\"
+    }
+    auto normalized = param.substr(starting_pos);
+    return granted_tree->Lookup(normalized, true);
+  }
+#endif
+  return granted_tree->Lookup(param, true);
+}
+
+}  // namespace
+
+namespace node {
+
+namespace permission {
+
+// allow = '*'
+// allow = '/tmp/,/home/example.js'
+void FSPermission::Apply(const std::string& allow, PermissionScope scope) {
+  for (const auto& res : SplitString(allow, ',')) {
+    if (res == "*") {
+      if (scope == PermissionScope::kFileSystemRead) {
+        deny_all_in_ = false;
+        allow_all_in_ = true;
+      } else {
+        deny_all_out_ = false;
+        allow_all_out_ = true;
+      }
+      return;
+    }
+    GrantAccess(scope, res);
+  }
+}
+
+void FSPermission::GrantAccess(PermissionScope perm, const std::string& res) {
+  const std::string path = WildcardIfDir(res);
+  if (perm == PermissionScope::kFileSystemRead) {
+    granted_in_fs_.Insert(path);
+    deny_all_in_ = false;
+  } else if (perm == PermissionScope::kFileSystemWrite) {
+    granted_out_fs_.Insert(path);
+    deny_all_out_ = false;
+  }
+}
+
+bool FSPermission::is_granted(PermissionScope perm,
+                              const std::string_view& param = "") {
+  switch (perm) {
+    case PermissionScope::kFileSystem:
+      return allow_all_in_ && allow_all_out_;
+    case PermissionScope::kFileSystemRead:
+      return !deny_all_in_ &&
+             ((param.empty() && allow_all_in_) || allow_all_in_ ||
+              is_tree_granted(&granted_in_fs_, param));
+    case PermissionScope::kFileSystemWrite:
+      return !deny_all_out_ &&
+             ((param.empty() && allow_all_out_) || allow_all_out_ ||
+              is_tree_granted(&granted_out_fs_, param));
+    default:
+      return false;
+  }
+}
+
+FSPermission::RadixTree::RadixTree() : root_node_(new Node("")) {}
+
+FSPermission::RadixTree::~RadixTree() {
+  FreeRecursivelyNode(root_node_);
+}
+
+bool FSPermission::RadixTree::Lookup(const std::string_view& s,
+                                     bool when_empty_return = false) {
+  FSPermission::RadixTree::Node* current_node = root_node_;
+  if (current_node->children.size() == 0) {
+    return when_empty_return;
+  }
+
+  unsigned int parent_node_prefix_len = current_node->prefix.length();
+  const std::string path(s);
+  auto path_len = path.length();
+
+  while (true) {
+    if (parent_node_prefix_len == path_len && current_node->IsEndNode()) {
+      return true;
+    }
+
+    auto node = current_node->NextNode(path, parent_node_prefix_len);
+    if (node == nullptr) {
+      return false;
+    }
+
+    current_node = node;
+    parent_node_prefix_len += current_node->prefix.length();
+    if (current_node->wildcard_child != nullptr &&
+        path_len >= (parent_node_prefix_len - 2 /* slash* */)) {
+      return true;
+    }
+  }
+}
+
+void FSPermission::RadixTree::Insert(const std::string& path) {
+  FSPermission::RadixTree::Node* current_node = root_node_;
+
+  unsigned int parent_node_prefix_len = current_node->prefix.length();
+  int path_len = path.length();
+
+  for (int i = 1; i <= path_len; ++i) {
+    bool is_wildcard_node = path[i - 1] == '*';
+    bool is_last_char = i == path_len;
+
+    if (is_wildcard_node || is_last_char) {
+      std::string node_path = path.substr(parent_node_prefix_len, i);
+      current_node = current_node->CreateChild(node_path);
+    }
+
+    if (is_wildcard_node) {
+      current_node = current_node->CreateWildcardChild();
+      parent_node_prefix_len = i;
+    }
+  }
+}
+
+}  // namespace permission
+}  // namespace node

src/permission/fs_permission.h

@@ -0,0 +1,152 @@
+#ifndef SRC_PERMISSION_FS_PERMISSION_H_
+#define SRC_PERMISSION_FS_PERMISSION_H_
+
+#if defined(NODE_WANT_INTERNALS) && NODE_WANT_INTERNALS
+
+#include "v8.h"
+
+#include <unordered_map>
+#include <vector>
+#include "permission/permission_base.h"
+#include "util.h"
+
+namespace node {
+
+namespace permission {
+
+class FSPermission final : public PermissionBase {
+ public:
+  void Apply(const std::string& deny, PermissionScope scope) override;
+  bool is_granted(PermissionScope perm, const std::string_view& param) override;
+
+  // For debugging purposes, use the gist function to print the whole tree
+  // https://gist.github.com/RafaelGSS/5b4f09c559a54f53f9b7c8c030744d19
+  struct RadixTree {
+    struct Node {
+      std::string prefix;
+      std::unordered_map<char, Node*> children;
+      Node* wildcard_child;
+
+      explicit Node(const std::string& pre)
+          : prefix(pre), wildcard_child(nullptr) {}
+
+      Node() : wildcard_child(nullptr) {}
+
+      Node* CreateChild(std::string prefix) {
+        char label = prefix[0];
+
+        Node* child = children[label];
+        if (child == nullptr) {
+          children[label] = new Node(prefix);
+          return children[label];
+        }
+
+        // swap prefix
+        unsigned int i = 0;
+        unsigned int prefix_len = prefix.length();
+        for (; i < child->prefix.length(); ++i) {
+          if (i > prefix_len || prefix[i] != child->prefix[i]) {
+            std::string parent_prefix = child->prefix.substr(0, i);
+            std::string child_prefix = child->prefix.substr(i);
+
+            child->prefix = child_prefix;
+            Node* split_child = new Node(parent_prefix);
+            split_child->children[child_prefix[0]] = child;
+            children[parent_prefix[0]] = split_child;
+
+            return split_child->CreateChild(prefix.substr(i));
+          }
+        }
+        return child->CreateChild(prefix.substr(i));
+      }
+
+      Node* CreateWildcardChild() {
+        if (wildcard_child != nullptr) {
+          return wildcard_child;
+        }
+        wildcard_child = new Node();
+        return wildcard_child;
+      }
+
+      Node* NextNode(const std::string& path, unsigned int idx) {
+        if (idx >= path.length()) {
+          return nullptr;
+        }
+
+        auto it = children.find(path[idx]);
+        if (it == children.end()) {
+          return nullptr;
+        }
+        auto child = it->second;
+        // match prefix
+        unsigned int prefix_len = child->prefix.length();
+        for (unsigned int i = 0; i < path.length(); ++i) {
+          if (i >= prefix_len || child->prefix[i] == '*') {
+            return child;
+          }
+
+          // Handle optional trailing
+          // path = /home/subdirectory
+          // child = subdirectory/*
+          if (idx >= path.length() &&
+              child->prefix[i] == node::kPathSeparator) {
+            continue;
+          }
+
+          if (path[idx++] != child->prefix[i]) {
+            return nullptr;
+          }
+        }
+        return child;
+      }
+
+      // A node can be a *end* node and have children
+      // E.g: */slower*, */slown* are inserted:
+      // /slow
+      // ---> er
+      // ---> n
+      // If */slow* is inserted right after, it will create an
+      // empty node
+      // /slow
+      // ---> '\000' ASCII (0) || \0
+      // ---> er
+      // ---> n
+      bool IsEndNode() {
+        if (children.size() == 0) {
+          return true;
+        }
+        return children['\0'] != nullptr;
+      }
+    };
+
+    RadixTree();
+    ~RadixTree();
+    void Insert(const std::string& s);
+    bool Lookup(const std::string_view& s) { return Lookup(s, false); }
+    bool Lookup(const std::string_view& s, bool when_empty_return);
+
+   private:
+    Node* root_node_;
+  };
+
+ private:
+  void GrantAccess(PermissionScope scope, const std::string& param);
+  void RestrictAccess(PermissionScope scope,
+                      const std::vector<std::string>& params);
+  // fs granted on startup
+  RadixTree granted_in_fs_;
+  RadixTree granted_out_fs_;
+
+  bool deny_all_in_ = true;
+  bool deny_all_out_ = true;
+
+  bool allow_all_in_ = false;
+  bool allow_all_out_ = false;
+};
+
+}  // namespace permission
+
+}  // namespace node
+
+#endif  // defined(NODE_WANT_INTERNALS) && NODE_WANT_INTERNALS
+#endif  // SRC_PERMISSION_FS_PERMISSION_H_