wind+libui: Run wind as a separate user

base/etc/group

@@ -1,3 +1,4 @@
 root:!:0:
-users:!:1:
+users:!:1:selene
+wind:!:2:selene
 selene:!:1000:

base/etc/passwd

@@ -1,2 +1,3 @@
 root:toor:0:0:Administrator:/:/usr/bin/sh
+wind:!:2:2:Window Manager:/:/usr/bin/init
 selene:moon:1000:1000:User:/home/selene:/usr/bin/sh

libos/src/SharedMemory.cpp

@@ -19,7 +19,7 @@ namespace os::SharedMemory
 {
     Result<u8*> create(StringView path, usize size)
     {
-        int fd = shm_open(path.chars(), O_RDWR | O_CREAT | O_EXCL, 0600);
+        int fd = shm_open(path.chars(), O_RDWR | O_CREAT | O_EXCL, 0660);
         if (fd < 0)
         {
             int olderr = errno;
@@ -57,7 +57,7 @@ namespace os::SharedMemory
 
     Result<u8*> adopt(StringView path, usize size, bool delete_fs)
     {
-        int fd = shm_open(path.chars(), O_RDWR, 0600);
+        int fd = shm_open(path.chars(), O_RDWR, 0660);
         if (delete_fs) shm_unlink(path.chars());
         if (fd < 0) return err(errno);
 

libui/include/ui/ipc/Server.h

@@ -19,6 +19,7 @@ namespace ui
     {
         IPC_ENUM_SERVER(ui),
         CREATE_WINDOW_ID,
+        REMOVE_SHM_ID,
         SET_WINDOW_TITLE_ID,
         INVALIDATE_ID,
         CLOSE_WINDOW_ID,
@@ -41,6 +42,13 @@ namespace ui
         WindowType type;
     };
 
+    struct RemoveSharedMemoryRequest
+    {
+        static constexpr u8 ID = REMOVE_SHM_ID;
+
+        int window;
+    };
+
     struct SetWindowTitleRequest
     {
         static constexpr u8 ID = SET_WINDOW_TITLE_ID;

libui/src/Window.cpp

@@ -8,6 +8,7 @@
  */
 
 #include <luna/String.h>
+#include <os/File.h>
 #include <os/SharedMemory.h>
 #include <sys/mman.h>
 #include <ui/App.h>
@@ -27,13 +28,17 @@ namespace ui
 
         auto path = COPY_IPC_STRING(response.shm_path);
 
-        u32* pixels = (u32*)TRY(os::SharedMemory::adopt(path.view(), rect.height * rect.width * 4));
+        u32* pixels = (u32*)TRY(os::SharedMemory::adopt(path.view(), rect.height * rect.width * 4, false));
 
         window->m_canvas = ui::Canvas { rect.width, rect.height, rect.width, (u8*)pixels };
         window->m_id = response.window;
 
         Window* p = window.ptr();
 
+        ui::RemoveSharedMemoryRequest shm_request;
+        shm_request.window = response.window;
+        os::IPC::send_async(App::the().client(), shm_request);
+
         App::the().register_window(move(window), {});
 
         return p;

wind/IPC.cpp

@@ -5,6 +5,7 @@
 #include <luna/String.h>
 #include <os/File.h>
 #include <os/SharedMemory.h>
+#include <sys/mman.h>
 #include <time.h>
 
 #define TRY_OR_IPC_ERROR(expr)                                                                                         \
@@ -94,10 +95,23 @@ static Result<void> handle_create_window_message(Client& client)
     ui::CreateWindowResponse response;
     response.window = id;
     SET_IPC_STRING(response.shm_path, shm_path.chars());
+    window->shm_path = move(shm_path);
     os::IPC::send_async(client.conn, response);
     return {};
 }
 
+static Result<void> handle_remove_shm_message(Client& client)
+{
+    ui::RemoveSharedMemoryRequest request;
+    READ_MESSAGE(request);
+
+    CHECK_WINDOW_ID(request);
+
+    shm_unlink(client.windows[request.window]->shm_path.chars());
+
+    return {};
+}
+
 static Result<void> handle_set_window_title_message(Client& client)
 {
     ui::SetWindowTitleRequest request;
@@ -162,6 +176,7 @@ namespace wind
         switch (id)
         {
         case ui::CREATE_WINDOW_ID: return handle_create_window_message(client);
+        case ui::REMOVE_SHM_ID: return handle_remove_shm_message(client);
         case ui::SET_WINDOW_TITLE_ID: return handle_set_window_title_message(client);
         case ui::INVALIDATE_ID: return handle_invalidate_message(client);
         case ui::CLOSE_WINDOW_ID: return handle_close_window_message(client);

wind/Window.h

@@ -16,6 +16,7 @@ struct Window : public LinkedListNode<Window>
     ui::Rect contents;
     u32* pixels;
     String name;
+    String shm_path;
     bool dirty { false };
     Client* client;
     int id;

wind/main.cpp

@@ -6,6 +6,7 @@
 #include "Screen.h"
 #include "Window.h"
 #include <errno.h>
+#include <grp.h>
 #include <moon/Keyboard.h>
 #include <os/ArgumentParser.h>
 #include <os/File.h>
@@ -17,6 +18,7 @@
 #include <string.h>
 #include <sys/ioctl.h>
 #include <sys/poll.h>
+#include <sys/stat.h>
 #include <time.h>
 #include <unistd.h>
 
@@ -52,6 +54,31 @@ static void debug(const Vector<OwnedPtr<Client>>& clients)
     os::println("--- wind: END DEBUG OUTPUT ---");
 }
 
+Result<void> set_supplementary_groups(const char* name)
+{
+    Vector<gid_t> extra_groups;
+
+    setgrent();
+    group* grp;
+    while ((grp = getgrent()))
+    {
+        for (char** user = grp->gr_mem; *user; user++)
+        {
+            if (!strcmp(*user, name))
+            {
+                os::println("Adding supplementary group: %d", grp->gr_gid);
+                TRY(extra_groups.try_append(grp->gr_gid));
+                break;
+            }
+        }
+    }
+    endgrent();
+
+    if (setgroups(static_cast<int>(extra_groups.size()), extra_groups.data()) < 0) return err(errno);
+
+    return {};
+}
+
 Result<int> luna_main(int argc, char** argv)
 {
     srand((unsigned)time(NULL));
@@ -95,25 +122,44 @@ Result<int> luna_main(int argc, char** argv)
         close(fd);
     }
 
-    clearenv();
-
-    if (!user.is_empty())
-    {
-        auto* pwd = getpwnam(user.chars());
-        if (pwd)
-        {
-            setgid(pwd->pw_gid);
-            setuid(pwd->pw_uid);
-        }
-    }
+    setegid(2);
+    seteuid(2);
 
     if (setsid() < 0) perror("setsid");
 
+    mode_t mask = umask(0002);
+
     auto server = TRY(os::LocalServer::create(socket_path, false));
     TRY(server->listen(20));
 
-    StringView args[] = { "/usr/bin/init"_sv, "--user"_sv };
-    TRY(os::Process::spawn("/usr/bin/init"_sv, Slice<StringView> { args, 2 }, false));
+    umask(mask);
+
+    seteuid(0);
+
+    clearenv();
+
+    pid_t child = TRY(os::Process::fork());
+    if (!child)
+    {
+        if (!user.is_empty())
+        {
+            auto* pwd = getpwnam(user.chars());
+            if (pwd)
+            {
+                TRY(set_supplementary_groups(user.chars()));
+                setgid(pwd->pw_gid);
+                setuid(pwd->pw_uid);
+            }
+        }
+
+        StringView args[] = { "/usr/bin/init"_sv, "--user"_sv };
+        TRY(os::Process::exec("/usr/bin/init"_sv, Slice<StringView> { args, 2 }, false));
+    }
+
+    umask(0002);
+
+    setuid(2);
+    setgid(2);
 
     ui::Color background = ui::Color::from_rgb(0x10, 0x10, 0x10);