Add experimental virtual display support for Linux

cmake/compile_definitions/linux.cmake

@@ -94,8 +94,16 @@ if(LIBDRM_FOUND AND LIBCAP_FOUND)
     include_directories(SYSTEM ${LIBCAP_INCLUDE_DIRS})
     list(APPEND PLATFORM_LIBRARIES ${LIBCAP_LIBRARIES})
     list(APPEND PLATFORM_TARGET_FILES
-            "${CMAKE_SOURCE_DIR}/src/platform/linux/kmsgrab.cpp")
+            "${CMAKE_SOURCE_DIR}/src/platform/linux/kmsgrab.cpp"
+            "${CMAKE_SOURCE_DIR}/src/platform/linux/virtual_display.h"
+            "${CMAKE_SOURCE_DIR}/src/platform/linux/virtual_display.cpp")
     list(APPEND SUNSHINE_DEFINITIONS EGL_NO_X11=1)
+
+    # Privileged helper for virtual display debugfs writes (cap_dac_override)
+    add_executable(apollo-vdisplay-helper
+            "${CMAKE_SOURCE_DIR}/src/platform/linux/vdisplay_helper.cpp")
+    set_target_properties(apollo-vdisplay-helper PROPERTIES CXX_STANDARD 17)
+    install(TARGETS apollo-vdisplay-helper RUNTIME DESTINATION "${CMAKE_INSTALL_BINDIR}")
 endif()
 
 # evdev

cmake/packaging/linux.cmake

@@ -31,6 +31,9 @@ else()
                 DESTINATION "${SYSTEMD_USER_UNIT_INSTALL_DIR}")
         install(FILES "${SUNSHINE_SOURCE_ASSETS_DIR}/linux/misc/60-sunshine.conf"
                 DESTINATION "${SYSTEMD_MODULES_LOAD_DIR}")
+        install(FILES "${SUNSHINE_SOURCE_ASSETS_DIR}/linux/misc/apollo-sysusers.conf"
+                DESTINATION "${CMAKE_INSTALL_PREFIX}/lib/sysusers.d"
+                RENAME "apollo.conf")
     endif()
 endif()
 
@@ -40,7 +43,9 @@ set(CPACK_RPM_POST_INSTALL_SCRIPT_FILE "${SUNSHINE_SOURCE_ASSETS_DIR}/linux/misc
 
 # Apply setcap for RPM
 # https://github.com/coreos/rpm-ostree/discussions/5036#discussioncomment-10291071
-set(CPACK_RPM_USER_FILELIST "%caps(cap_sys_admin+p) ${SUNSHINE_EXECUTABLE_PATH}")
+set(CPACK_RPM_USER_FILELIST
+        "%caps(cap_sys_admin+p) ${SUNSHINE_EXECUTABLE_PATH}"
+        "%attr(0750,root,apollo) %caps(cap_dac_override+ep) %{_bindir}/apollo-vdisplay-helper")
 
 # Dependencies
 set(CPACK_DEB_COMPONENT_INSTALL ON)

packaging/linux/Arch/sunshine.install

@@ -2,6 +2,17 @@ do_setcap() {
   setcap cap_sys_admin+p $(readlink -f usr/bin/sunshine)
 }
 
+do_vdisplay_helper() {
+  local helper=$(readlink -f usr/bin/apollo-vdisplay-helper 2>/dev/null)
+  if [ -x "$helper" ]; then
+    if getent group apollo >/dev/null 2>&1; then
+      chown root:apollo "$helper"
+      chmod 0750 "$helper"
+    fi
+    setcap cap_dac_override+ep "$helper"
+  fi
+}
+
 do_udev_reload() {
   udevadm control --reload-rules
   udevadm trigger --property-match=DEVNAME=/dev/uinput
@@ -12,12 +23,14 @@ do_udev_reload() {
 
 post_install() {
   do_setcap
+  do_vdisplay_helper
   do_udev_reload
   modprobe uhid
 }
 
 post_upgrade() {
   do_setcap
+  do_vdisplay_helper
   do_udev_reload
   modprobe uhid
 }

packaging/linux/fedora/Sunshine.spec

@@ -212,7 +212,7 @@ cd %{_builddir}/Sunshine/build
 %make_install
 
 %post
-# Note: this is copied from the postinst script
+# Note: this should be kept in sync with src_assets/linux/misc/postinst
 
 # Load uhid (DS5 emulation)
 echo "Loading uhid kernel module for DS5 emulation."
@@ -222,6 +222,30 @@ modprobe uhid
 if [ ! -x "$(command -v rpm-ostree)" ]; then
   echo "Not in an rpm-ostree environment, proceeding with post install steps."
 
+  # Create apollo system group if it doesn't exist
+  if ! getent group apollo >/dev/null 2>&1; then
+    if [ -x "$(command -v groupadd)" ]; then
+      groupadd --system apollo
+      echo "Created 'apollo' system group."
+    fi
+  fi
+
+  # Add the installing user to the apollo group
+  if [ -n "$SUDO_USER" ] && [ "$SUDO_USER" != "root" ]; then
+    target_user="$SUDO_USER"
+  elif [ -n "$PKEXEC_UID" ]; then
+    target_user=$(id -nu "$PKEXEC_UID" 2>/dev/null)
+  else
+    target_user=""
+  fi
+
+  if [ -n "$target_user" ]; then
+    if ! id -nG "$target_user" 2>/dev/null | grep -qw apollo; then
+      usermod -aG apollo "$target_user"
+      echo "Added '$target_user' to 'apollo' group. Log out and back in for group to take effect."
+    fi
+  fi
+
   # Trigger udev rule reload for /dev/uinput and /dev/uhid
   path_to_udevadm=$(which udevadm)
   if [ -x "$path_to_udevadm" ]; then
@@ -240,7 +264,7 @@ fi
 %files
 # Executables
 %caps(cap_sys_admin+p) %{_bindir}/sunshine
-%caps(cap_sys_admin+p) %{_bindir}/sunshine-*
+%attr(0750,root,apollo) %caps(cap_dac_override+ep) %{_bindir}/apollo-vdisplay-helper
 
 # Systemd unit file for user services
 %{_userunitdir}/sunshine.service

src/config.cpp

@@ -516,6 +516,8 @@ namespace config {
     "1920x1080x60",  // fallback_mode
     false, // isolated Display
     false, // ignore_encoder_probe_failure
+    false, // linux_virtual_display_experimental
+    {},  // vdisplay_connector
   };
 
   audio_t audio {
@@ -1209,6 +1211,8 @@ namespace config {
     string_f(vars, "fallback_mode", video.fallback_mode);
     bool_f(vars, "isolated_virtual_display_option", video.isolated_virtual_display_option);
     bool_f(vars, "ignore_encoder_probe_failure", video.ignore_encoder_probe_failure);
+    bool_f(vars, "linux_virtual_display_experimental", video.linux_virtual_display_experimental);
+    string_f(vars, "vdisplay_connector", video.vdisplay_connector);
 
     path_f(vars, "pkey", nvhttp.pkey);
     path_f(vars, "cert", nvhttp.cert);

src/config.h

@@ -149,6 +149,8 @@ namespace config {
     std::string fallback_mode;
     bool isolated_virtual_display_option;
     bool ignore_encoder_probe_failure;
+    bool linux_virtual_display_experimental;
+    std::string vdisplay_connector;
   };
 
   struct audio_t {

src/main.cpp

@@ -26,6 +26,8 @@
 #ifdef _WIN32
   #include "platform/windows/misc.h"
   #include "platform/windows/virtual_display.h"
+#elif defined(__linux__) && defined(SUNSHINE_BUILD_DRM)
+  #include "platform/linux/virtual_display.h"
 #endif
 
 #define PROBE_DISPLAY_UUID "38F72B96-B00C-4F21-8B6C-E1BFF1602B0E"
@@ -206,6 +208,12 @@ int main(int argc, char *argv[]) {
     BOOST_LOG(error) << "Display device session failed to initialize"sv;
   }
 
+#if defined(__linux__) && defined(SUNSHINE_BUILD_DRM)
+  if (config::video.linux_virtual_display_experimental) {
+    linux_vdisplay::recover_crash_state();
+  }
+#endif
+
 #ifdef _WIN32
   // Modify relevant NVIDIA control panel settings if the system has corresponding gpu
   if (nvprefs_instance.load()) {

src/platform/linux/vdisplay_helper.cpp

@@ -0,0 +1,156 @@
+/**
+ * @file src/platform/linux/vdisplay_helper.cpp
+ * @brief Privileged helper for virtual display debugfs/sysfs writes.
+ *
+ * Installed with cap_dac_override+ep so the main apollo process
+ * does not need CAP_DAC_OVERRIDE in its capability set.
+ */
+#include <cstdint>
+#include <cstdio>
+#include <cstring>
+#include <fcntl.h>
+#include <regex.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+static bool
+  validate_path(const char *path) {
+  if (strcmp(path, "/sys/kernel/debug/dri") == 0) {
+    return true;
+  }
+
+  static const char *patterns[] = {
+    "^/sys/kernel/debug/dri/[0-9]+/[A-Za-z]+(-[A-Za-z]+)*-[0-9]+/edid_override$",
+    "^/sys/kernel/debug/dri/[0-9]+/[A-Za-z]+(-[A-Za-z]+)*-[0-9]+/trigger_hotplug$",
+    "^/sys/class/drm/card[0-9]+-[A-Za-z]+(-[A-Za-z]+)*-[0-9]+/status$",
+  };
+
+  for (auto pattern : patterns) {
+    regex_t re;
+    if (regcomp(&re, pattern, REG_EXTENDED | REG_NOSUB) != 0) {
+      continue;
+    }
+    int match = regexec(&re, path, 0, nullptr, 0);
+    regfree(&re);
+    if (match == 0) {
+      return true;
+    }
+  }
+
+  return false;
+}
+
+static int
+  safe_open(const char *path) {
+  return open(path, O_WRONLY | O_NOFOLLOW);
+}
+
+static int
+  cmd_write_edid(const char *path) {
+  uint8_t buf[256];
+  ssize_t total = 0;
+  while (total < static_cast<ssize_t>(sizeof(buf))) {
+    ssize_t n = read(STDIN_FILENO, buf + total, sizeof(buf) - total);
+    if (n <= 0) {
+      break;
+    }
+    total += n;
+  }
+  if (total != 128 && total != 256) {
+    fprintf(stderr, "Invalid EDID size: %zd\n", total);
+    return 3;
+  }
+  int fd = safe_open(path);
+  if (fd < 0) {
+    perror("open");
+    return 4;
+  }
+  ssize_t written = write(fd, buf, total);
+  close(fd);
+  if (written != total) {
+    perror("write");
+    return 5;
+  }
+  return 0;
+}
+
+static int
+  cmd_clear_edid(const char *path) {
+  int fd = safe_open(path);
+  if (fd < 0) {
+    perror("open");
+    return 4;
+  }
+  ssize_t n = write(fd, "reset", 5);
+  if (n < 0) {
+    lseek(fd, 0, SEEK_SET);
+    write(fd, "", 0);
+  }
+  close(fd);
+  return 0;
+}
+
+static int
+  cmd_write_string(const char *path, const char *value) {
+  int fd = safe_open(path);
+  if (fd < 0) {
+    perror("open");
+    return 4;
+  }
+  ssize_t n = write(fd, value, strlen(value));
+  close(fd);
+  if (n < 0) {
+    perror("write");
+    return 5;
+  }
+  return 0;
+}
+
+int main(int argc, char *argv[]) {
+  if (argc < 3) {
+    fprintf(stderr, "Usage: %s <command> <path> [value]\n", argv[0]);
+    return 1;
+  }
+
+  const char *command = argv[1];
+  const char *path = argv[2];
+
+  if (!validate_path(path)) {
+    fprintf(stderr, "Path rejected: %s\n", path);
+    return 2;
+  }
+
+  if (strcmp(command, "write-edid") == 0) {
+    return cmd_write_edid(path);
+  }
+  if (strcmp(command, "clear-edid") == 0) {
+    return cmd_clear_edid(path);
+  }
+  if (strcmp(command, "write-string") == 0) {
+    if (argc < 4) {
+      fprintf(stderr, "write-string requires a value argument\n");
+      return 1;
+    }
+    const char *value = argv[3];
+    static const char *allowed_values[] = {"1", "on", "off", "detect"};
+    bool valid = false;
+    for (auto v : allowed_values) {
+      if (strcmp(value, v) == 0) {
+        valid = true;
+        break;
+      }
+    }
+    if (!valid) {
+      fprintf(stderr, "Value rejected: %s\n", value);
+      return 2;
+    }
+    return cmd_write_string(path, value);
+  }
+  if (strcmp(command, "check-path") == 0) {
+    struct stat st;
+    return stat(path, &st) == 0 ? 0 : 1;
+  }
+
+  fprintf(stderr, "Unknown command: %s\n", command);
+  return 1;
+}