src: make copies of startup environment variables

Mutations of the environment can invalidate pointers to environment
variables, so make `secure_getenv()` copy them out instead of returning
pointers.

PR-URL: https://github.com/nodejs/node/pull/11051
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Sam Roberts <vieuxtech@gmail.com>

5 files changed, 49 insertions, 33 deletions

diff --git a/src/node.cc b/src/node.cc
index a678c177f3..8c5e811d6e 100644
--- a/src/node.cc
+++ b/src/node.cc
@@ -156,7 +156,7 @@ static const char* trace_enabled_categories = nullptr;
 
 #if defined(NODE_HAVE_I18N_SUPPORT)
 // Path to ICU data (for i18n / Intl)
-static const char* icu_data_dir = nullptr;
+static std::string icu_data_dir;  // NOLINT(runtime/string)
 #endif
 
 // used by C++ modules as well
@@ -189,7 +189,7 @@ bool trace_warnings = false;
 bool config_preserve_symlinks = false;
 
 // Set in node.cc by ParseArgs when --redirect-warnings= is used.
-const char* config_warning_file;
+std::string config_warning_file;  // NOLINT(runtime/string)
 
 bool v8_initialized = false;
 
@@ -924,12 +924,21 @@ Local<Value> UVException(Isolate* isolate,
 
 
 // Look up environment variable unless running as setuid root.
-inline const char* secure_getenv(const char* key) {
+inline bool SafeGetenv(const char* key, std::string* text) {
 #ifndef _WIN32
-  if (getuid() != geteuid() || getgid() != getegid())
-    return nullptr;
+  // TODO(bnoordhuis) Should perhaps also check whether getauxval(AT_SECURE)
+  // is non-zero on Linux.
+  if (getuid() != geteuid() || getgid() != getegid()) {
+    text->clear();
+    return false;
+  }
 #endif
-  return getenv(key);
+  if (const char* value = getenv(key)) {
+    *text = value;
+    return true;
+  }
+  text->clear();
+  return false;
 }
 
 
@@ -3089,11 +3098,11 @@ void SetupProcessObject(Environment* env,
 #if defined(NODE_HAVE_I18N_SUPPORT) && defined(U_ICU_VERSION)
   // ICU-related versions are now handled on the js side, see bootstrap_node.js
 
-  if (icu_data_dir != nullptr) {
+  if (!icu_data_dir.empty()) {
     // Did the user attempt (via env var or parameter) to set an ICU path?
     READONLY_PROPERTY(process,
                       "icu_data_dir",
-                      OneByteString(env->isolate(), icu_data_dir));
+                      OneByteString(env->isolate(), icu_data_dir.c_str()));
   }
 #endif
 
@@ -3741,7 +3750,7 @@ static void ParseArgs(int* argc,
 #endif /* HAVE_OPENSSL */
 #if defined(NODE_HAVE_I18N_SUPPORT)
     } else if (strncmp(arg, "--icu-data-dir=", 15) == 0) {
-      icu_data_dir = arg + 15;
+      icu_data_dir.assign(arg, 15);
 #endif
     } else if (strcmp(arg, "--expose-internals") == 0 ||
                strcmp(arg, "--expose_internals") == 0) {
@@ -4228,13 +4237,14 @@ void Init(int* argc,
 #endif
 
   // Allow for environment set preserving symlinks.
-  if (auto preserve_symlinks = secure_getenv("NODE_PRESERVE_SYMLINKS")) {
-    config_preserve_symlinks = (*preserve_symlinks == '1');
+  {
+    std::string text;
+    config_preserve_symlinks =
+        SafeGetenv("NODE_PRESERVE_SYMLINKS", &text) && text[0] == '1';
   }
 
-  if (auto redirect_warnings = secure_getenv("NODE_REDIRECT_WARNINGS")) {
-    config_warning_file = redirect_warnings;
-  }
+  if (config_warning_file.empty())
+    SafeGetenv("NODE_REDIRECT_WARNINGS", &config_warning_file);
 
   // Parse a few arguments which are specific to Node.
   int v8_argc;
@@ -4262,12 +4272,11 @@ void Init(int* argc,
 #endif
 
 #if defined(NODE_HAVE_I18N_SUPPORT)
-  if (icu_data_dir == nullptr) {
-    // if the parameter isn't given, use the env variable.
-    icu_data_dir = secure_getenv("NODE_ICU_DATA");
-  }
+  // If the parameter isn't given, use the env variable.
+  if (icu_data_dir.empty())
+    SafeGetenv("NODE_ICU_DATA", &icu_data_dir);
   // Initialize ICU.
-  // If icu_data_dir is nullptr here, it will load the 'minimal' data.
+  // If icu_data_dir is empty here, it will load the 'minimal' data.
   if (!i18n::InitializeICUDirectory(icu_data_dir)) {
     FatalError(nullptr, "Could not initialize ICU "
                      "(check NODE_ICU_DATA or --icu-data-dir parameters)");
@@ -4532,8 +4541,11 @@ int Start(int argc, char** argv) {
   Init(&argc, const_cast<const char**>(argv), &exec_argc, &exec_argv);
 
 #if HAVE_OPENSSL
-  if (const char* extra = secure_getenv("NODE_EXTRA_CA_CERTS"))
-    crypto::UseExtraCaCerts(extra);
+  {
+    std::string extra_ca_certs;
+    if (SafeGetenv("NODE_EXTRA_CA_CERTS", &extra_ca_certs))
+      crypto::UseExtraCaCerts(extra_ca_certs);
+  }
 #ifdef NODE_FIPS_MODE
   // In the case of FIPS builds we should make sure
   // the random source is properly initialized first.
@@ -4542,7 +4554,7 @@ int Start(int argc, char** argv) {
   // V8 on Windows doesn't have a good source of entropy. Seed it from
   // OpenSSL's pool.
   V8::SetEntropySource(crypto::EntropySource);
-#endif
+#endif  // HAVE_OPENSSL
 
   v8_platform.Initialize(v8_thread_pool_size);
   // Enable tracing when argv has --trace-events-enabled.
diff --git a/src/node_config.cc b/src/node_config.cc
index 60001207f1..a096372812 100644
--- a/src/node_config.cc
+++ b/src/node_config.cc
@@ -46,11 +46,12 @@ void InitConfig(Local<Object> target,
   if (config_preserve_symlinks)
     READONLY_BOOLEAN_PROPERTY("preserveSymlinks");
 
-  if (config_warning_file != nullptr) {
+  if (!config_warning_file.empty()) {
     Local<String> name = OneByteString(env->isolate(), "warningFile");
     Local<String> value = String::NewFromUtf8(env->isolate(),
-                                              config_warning_file,
-                                              v8::NewStringType::kNormal)
+                                              config_warning_file.data(),
+                                              v8::NewStringType::kNormal,
+                                              config_warning_file.size())
                                                 .ToLocalChecked();
     target->DefineOwnProperty(env->context(), name, value).FromJust();
   }
diff --git a/src/node_i18n.cc b/src/node_i18n.cc
index a98fdca4d1..40d048fa36 100644
--- a/src/node_i18n.cc
+++ b/src/node_i18n.cc
@@ -404,12 +404,8 @@ static void GetVersion(const FunctionCallbackInfo<Value>& args) {
   }
 }
 
-bool InitializeICUDirectory(const char* icu_data_path) {
-  if (icu_data_path != nullptr) {
-    flag_icu_data_dir = true;
-    u_setDataDirectory(icu_data_path);
-    return true;  // no error
-  } else {
+bool InitializeICUDirectory(const std::string& path) {
+  if (path.empty()) {
     UErrorCode status = U_ZERO_ERROR;
 #ifdef NODE_HAVE_SMALL_ICU
     // install the 'small' data.
@@ -418,6 +414,10 @@ bool InitializeICUDirectory(const char* icu_data_path) {
     // no small data, so nothing to do.
 #endif  // !NODE_HAVE_SMALL_ICU
     return (status == U_ZERO_ERROR);
+  } else {
+    flag_icu_data_dir = true;
+    u_setDataDirectory(path.c_str());
+    return true;  // No error.
   }
 }
 
diff --git a/src/node_i18n.h b/src/node_i18n.h
index 21a579526d..0bfd3c5c85 100644
--- a/src/node_i18n.h
+++ b/src/node_i18n.h
@@ -4,6 +4,7 @@
 #if defined(NODE_WANT_INTERNALS) && NODE_WANT_INTERNALS
 
 #include "node.h"
+#include <string>
 
 #if defined(NODE_HAVE_I18N_SUPPORT)
 
@@ -13,7 +14,7 @@ extern bool flag_icu_data_dir;
 
 namespace i18n {
 
-bool InitializeICUDirectory(const char* icu_data_path);
+bool InitializeICUDirectory(const std::string& path);
 
 int32_t ToASCII(MaybeStackBuffer<char>* buf,
                 const char* input,
diff --git a/src/node_internals.h b/src/node_internals.h
index 7c1b79d62f..9d57becc26 100644
--- a/src/node_internals.h
+++ b/src/node_internals.h
@@ -13,6 +13,8 @@
 #include <stdint.h>
 #include <stdlib.h>
 
+#include <string>
+
 struct sockaddr;
 
 // Variation on NODE_DEFINE_CONSTANT that sets a String value.
@@ -45,7 +47,7 @@ extern bool config_preserve_symlinks;
 // Set in node.cc by ParseArgs when --redirect-warnings= is used.
 // Used to redirect warning output to a file rather than sending
 // it to stderr.
-extern const char* config_warning_file;
+extern std::string config_warning_file;  // NOLINT(runtime/string)
 
 // Tells whether it is safe to call v8::Isolate::GetCurrent().
 extern bool v8_initialized;