NC | supplemental groups - getpwuid concurrency issue

src/native/fs/fs_napi.cpp

@@ -168,7 +168,6 @@ typedef std::map<std::string, std::string> XattrMap;
 const char* gpfs_dl_path = std::getenv("GPFS_DL_PATH");
 
 int gpfs_lib_file_exists = -1;
-static long PASSWD_BUF_SIZE = -1;
 
 static int (*dlsym_gpfs_fcntl)(gpfs_file_t file, void* arg) = 0;
 
@@ -1410,12 +1409,13 @@ struct GetPwName : public FSWorker
     }
     virtual void Work()
     {
-        _buf.reset(new char[PASSWD_BUF_SIZE]);
+        const long passwd_buf_size = ThreadScope::get_passwd_buf_size();
+        _buf.reset(new char[passwd_buf_size]);
         if (!_buf) {
             SetSyscallError();
             return;
         }
-        int rc = getpwnam_r(_user.c_str(), &_pwd, _buf.get(), PASSWD_BUF_SIZE, &_getpwnam_res);
+        int rc = getpwnam_r(_user.c_str(), &_pwd, _buf.get(), passwd_buf_size, &_getpwnam_res);
         if (rc != 0) {
             SetSyscallError();
             return;
@@ -2419,7 +2419,7 @@ fs_napi(Napi::Env env, Napi::Object exports)
     if (passwd_bufsize == -1) {
         passwd_bufsize = 16384;
     }
-    PASSWD_BUF_SIZE = passwd_bufsize;
+    ThreadScope::set_passwd_buf_size(passwd_bufsize);
 
 
 #ifdef O_DIRECT

src/native/util/os.h

@@ -41,6 +41,16 @@ class ThreadScope
         change_user();
     }
 
+    static void set_passwd_buf_size(int buf_size)
+    {
+        passwd_buf_size = buf_size;
+    }
+
+    static long get_passwd_buf_size()
+    {
+        return passwd_buf_size;
+    }
+
     int add_thread_capabilities();
 
     const static uid_t orig_uid;
@@ -55,6 +65,8 @@ class ThreadScope
     uid_t _uid;
     gid_t _gid;
     std::vector<gid_t> _groups;
+
+    static long passwd_buf_size;
 };
 
 } // namespace noobaa

src/native/util/os_darwin.cpp

@@ -43,15 +43,19 @@ get_current_uid()
 const uid_t ThreadScope::orig_uid = getuid();
 const gid_t ThreadScope::orig_gid = getgid();
 const std::vector<gid_t> ThreadScope::orig_groups = get_process_groups();
+long ThreadScope::passwd_buf_size = -1;
 
 static int
 get_supplemental_groups_by_uid(uid_t uid, std::vector<gid_t>& groups)
 {
-    // getpwuid will only indicate if an error happened by setting errno. set it to 0, so will know if there is a change
-    errno = 0;
-    struct passwd* pw = getpwuid(uid);
+    const long passwd_buf_size = ThreadScope::get_passwd_buf_size();
+    std::unique_ptr<char[]> buf(new char[passwd_buf_size]);
+    struct passwd pwd;
+    struct passwd *pw = NULL;
+
+    const int res = getpwuid_r(uid, &pwd, buf.get(), passwd_buf_size, &pw);
     if (pw == NULL) {
-        if (errno == 0) {
+        if (res == 0) {
             // LOG("get_supplemental_groups_by_uid: no record for uid " << uid);
         } else {
             LOG("WARNING: get_supplemental_groups_by_uid: getpwuid failed: " << strerror(errno));

src/native/util/os_linux.cpp

@@ -27,17 +27,21 @@ get_current_uid()
 
 const uid_t ThreadScope::orig_uid = getuid();
 const gid_t ThreadScope::orig_gid = getgid();
+long ThreadScope::passwd_buf_size = -1;
 
 const std::vector<gid_t> ThreadScope::orig_groups = get_process_groups();
 
 static int
 get_supplemental_groups_by_uid(uid_t uid, std::vector<gid_t>& groups)
 {
-    // getpwuid will only indicate if an error happened by setting errno. set it to 0, so will know if there is a change
-    errno = 0;
-    struct passwd* pw = getpwuid(uid);
+    const long passwd_buf_size = ThreadScope::get_passwd_buf_size();
+    std::unique_ptr<char[]> buf(new char[passwd_buf_size]);
+    struct passwd pwd;
+    struct passwd *pw = NULL;
+
+    const int res = getpwuid_r(uid, &pwd, buf.get(), passwd_buf_size, &pw);
     if (pw == NULL) {
-        if (errno == 0) {
+        if (res == 0) {
             // LOG("get_supplemental_groups_by_uid: no record for uid " << uid);
         } else {
             LOG("WARNING: get_supplemental_groups_by_uid: getpwuid failed: " << strerror(errno));