Revert "[SystemSan] Add feature for opting out." (#9386)

Reverts google/oss-fuzz#9221.

Nothing was setting this yet.

infra/experimental/SystemSan/SystemSan.cpp

@@ -178,11 +178,6 @@ std::string read_string(pid_t pid, unsigned long reg, unsigned long length) {
 
 void inspect_for_injection(pid_t pid, const user_regs_struct &regs) {
   // Inspect a PID's registers for the sign of shell injection.
-
-  static bool is_enabled = check_enabled("shell_injection");
-  if (not is_enabled)
-    return;
-
   std::string path = read_string(pid, regs.rdi, kTripWire.length());
   if (!path.length()) {
     return;
@@ -276,11 +271,6 @@ void match_error_pattern(std::string buffer, std::string shell, pid_t pid) {
 
 void inspect_for_corruption(pid_t pid, const user_regs_struct &regs) {
   // Inspect a PID's registers for shell corruption.
-
-  static bool is_enabled = check_enabled("shell_corruption");
-  if (not is_enabled)
-    return;
-
   std::string buffer = read_string(pid, regs.rsi, regs.rdx);
   debug_log("Write buffer: %s\n", buffer.c_str());
   match_error_pattern(buffer, g_shell_pids[pid], pid);
@@ -316,11 +306,6 @@ bool has_unprintable(const std::string &value) {
 
 void inspect_for_arbitrary_file_open(pid_t pid, const user_regs_struct &regs) {
   // Inspect a PID's register for the sign of arbitrary file open.
-
-  static bool is_enabled = check_enabled("arbitrary_file_open");
-  if (not is_enabled)
-    return;
-
   std::string path = read_string(pid, regs.rsi, kRootDirMaxLength);
   if (!path.length()) {
     return;
@@ -362,10 +347,6 @@ void report_bug_in_process(std::string bug_type, pid_t pid) {
 
 void inspect_for_evil_link(pid_t pid, const user_regs_struct &regs) {
   (void) regs;
-
-  static bool is_enabled = check_enabled("malicious_symlink_following");
-  if (not is_enabled)
-    return;
   std::string contents = read_evil_link_bombfile();
   if ((contents.compare(kEvilLinkBombfileContents)) != 0) {
 
@@ -374,10 +355,6 @@ void inspect_for_evil_link(pid_t pid, const user_regs_struct &regs) {
 }
 
 void evil_openat_hook(pid_t pid, const user_regs_struct &regs) {
-  static bool is_enabled = check_enabled("malicious_symlink_following");
-  if (not is_enabled)
-    return;
-
   std::string path = read_string(pid, regs.rsi, kPathMax);
   if (!path.length()) {
     return;

infra/experimental/SystemSan/inspect_dns.cpp

@@ -38,10 +38,6 @@ const size_t kDnsHeaderLen = 12;
 
 
 void inspect_for_arbitrary_dns_connect(pid_t pid, const user_regs_struct &regs) {
-  static bool is_enabled = check_enabled("arbitrary_dns_resolution");
-  if (not is_enabled)
-    return;
-
   auto memory = read_memory(pid, regs.rsi, sizeof(struct sockaddr_in));
   if (memory.size()) {
     struct sockaddr_in * sa = reinterpret_cast<struct sockaddr_in *>(memory.data());

infra/experimental/SystemSan/inspect_utils.cpp

@@ -51,19 +51,6 @@ std::vector<std::byte> read_memory(pid_t pid, unsigned long long address,
   return memory;
 }
 
-bool check_enabled(std::string feature) {
-  for (auto & ch: feature)
-    ch = toupper(ch);
-
-  std::string env_var = "SYSTEMSAN_" + feature;
-  const char* value_charstr = getenv(env_var.c_str());
-  std::string no = "0";
-  if (!value_charstr)
-    value_charstr = no.c_str();
-  int value = atoi(value_charstr);
-  return static_cast<bool>(value);
-}
-
 void report_bug(std::string bug_type, pid_t tid) {
   // Report the bug found based on the bug code.
   std::cerr << "===BUG DETECTED: " << bug_type << "===" << std::endl;

infra/experimental/SystemSan/inspect_utils.h

@@ -37,4 +37,3 @@ std::vector<std::byte> read_memory(pid_t pid, unsigned long long address,
                                    size_t size);
 
 void report_bug(std::string bug_type, pid_t tid);
-bool check_enabled(std::string feature);