Merge pull request #1327 from mofarrell/kernel-publishers

Publisher system for kernel events in the kernel extension.

kernel/CMakeLists.txt

@@ -26,6 +26,7 @@ if(APPLE)
 
   # Set OS X platform-specific include paths.
   include_directories("${CMAKE_SOURCE_DIR}/kernel/include")
+  include_directories("${CMAKE_SOURCE_DIR}/kernel/src")
   include_directories("/System/Library/Frameworks/Kernel.framework/Headers")
   include_directories("/Applications/Xcode.app/Contents/Developer/Platforms/\
 MacOSX.platform/Developer/SDKs/MacOSX${APPLE_MIN_ABI}.sdk\
@@ -59,16 +60,20 @@ endif()
 
 # The set of platform-agnostic implementations.
 set(BASE_KERNEL_SOURCES
-  src/osquery.cpp
   src/circular_queue_kern.c
 )
 
-# TODO: Add a set of platform-specific files.
+file(GLOB APPLE_KERNEL_PUBLISHER_SOURCES "src/publishers/darwin/*.c")
+# Add a set of platform-specific files.
+set(APPLE_KERNEL_SOURCES
+  src/osquery.cpp
+  ${APPLE_KERNEL_PUBLISHER_SOURCES}
+)
 
 # Define kernel targets, each should be an extension/module.
 if(APPLE)
   # TODO: Remove the OS X requirement.
-  add_executable(base_kernel ${BASE_KERNEL_SOURCES})
+  add_executable(base_kernel ${APPLE_KERNEL_SOURCES} ${BASE_KERNEL_SOURCES})
   set_target_properties(base_kernel PROPERTIES COMPILE_FLAGS ${KERNEL_C_FLAGS} ${KERNEL_CXX_FLAGS})
   set_target_properties(base_kernel PROPERTIES LINK_FLAGS ${KERNEL_LINKER_FLAGS})
   set_target_properties(base_kernel PROPERTIES EXCLUDE_FROM_ALL true)

kernel/include/feeds.h

@@ -23,6 +23,19 @@
 #include <sys/param.h>
 #endif
 
+/** @brief Communication version between kernel and daemon.
+ *
+ *  A daemon may only connect to a kernel with the same communication version.
+ *  Bump this number when changing or adding any event structs.
+ */
+#define OSQUERY_KERNEL_COMMUNICATION_VERSION 1UL
+#ifdef KERNEL_TEST
+#define OSQUERY_KERNEL_COMM_VERSION \
+  (OSQUERY_KERNEL_COMMUNICATION_VERSION | (1UL << 63))
+#else
+#define OSQUERY_KERNEL_COMM_VERSION OSQUERY_KERNEL_COMMUNICATION_VERSION
+#endif
+
 #ifdef __cplusplus
 extern "C" {
 #endif
@@ -36,7 +49,6 @@ extern "C" {
  * a reentrant testing IOCTL call that adds test events to the cqueue structure.
  */
 
-
 //
 // Event feed types
 //
@@ -51,7 +63,7 @@ typedef enum {
   OSQUERY_TEST_EVENT_1,
 #endif // KERNEL_TEST
 
-  OSQUERY_EVENT_NUM_EVENTS // Number of different event types.
+  OSQUERY_NUM_EVENTS // Number of different event types.
 } osquery_event_t;
 
 typedef struct {
@@ -122,6 +134,7 @@ typedef struct {
 typedef struct {
   osquery_event_t event;
   int subscribe;
+  void *udata;
 } osquery_subscription_args_t;
 
 // Flags for buffer sync options.
@@ -138,6 +151,7 @@ typedef struct {
 typedef struct {
   size_t size;      // Size of shared user kernel buffer.
   void *buffer;     // (Output) Pointer to buffer location.
+  uint64_t version; // osquery kernel communication version.
 } osquery_buf_allocate_args_t;
 
 // TODO: Choose a proper IOCTL num.

kernel/src/osquery.cpp

@@ -12,12 +12,8 @@
 #include <mach/mach_types.h>
 
 #include <kern/debug.h>
-#include <sys/vnode.h>
 #include <sys/errno.h>
 #include <sys/conf.h>
-#include <sys/proc.h>
-#include <sys/systm.h>
-#include <sys/kauth.h>
 #include <miscfs/devfs/devfs.h>
 #include <sys/vnode.h>
 
@@ -25,7 +21,7 @@
 #include <IOKit/IOMemoryDescriptor.h>
 #include <IOKit/IOLib.h>
 
-#include <feeds.h>
+#include "publishers.h"
 
 #include "circular_queue_kern.h"
 
@@ -49,7 +45,6 @@ static struct {
   void *devfs;
   int major_number;
   int open_count;
-  kauth_listener_t fileop_listener;
 
   lck_grp_attr_t *lck_grp_attr;
   lck_grp_t *lck_grp;
@@ -65,68 +60,6 @@ static struct {
   .major_number = OSQUERY_MAJOR
 };
 
-static int fileop_scope_callback(kauth_cred_t credential,
-                                 void *idata,
-                                 kauth_action_t action,
-                                 uintptr_t arg0,
-                                 uintptr_t arg1,
-                                 uintptr_t arg2,
-                                 uintptr_t arg3) {
-  vnode_t vp = (vnode_t)arg0;
-  if (action == KAUTH_FILEOP_EXEC && vp != NULL) {
-    // Someone is executing a file.
-    int path_len = MAXPATHLEN;
-
-    osquery_process_event_t *e =
-      (osquery_process_event_t *)osquery_cqueue_reserve(&osquery.cqueue,
-                                                        OSQUERY_PROCESS_EVENT);
-    if (e == NULL) {
-      // Failed to reserve space for the event.
-      return KAUTH_RESULT_DEFER;
-    }
-    e->pid = proc_selfpid();
-    e->ppid = proc_selfppid();
-    e->owner_uid = 0;
-    e->owner_gid = 0;
-    e->mode = -1;
-    vfs_context_t context = vfs_context_create(NULL);
-    if (context) {
-      struct vnode_attr vattr = {0};
-      VATTR_INIT(&vattr);
-      VATTR_WANTED(&vattr, va_uid);
-      VATTR_WANTED(&vattr, va_gid);
-      VATTR_WANTED(&vattr, va_mode);
-      VATTR_WANTED(&vattr, va_create_time);
-      VATTR_WANTED(&vattr, va_access_time);
-      VATTR_WANTED(&vattr, va_modify_time);
-      VATTR_WANTED(&vattr, va_change_time);
-
-      if (vnode_getattr(vp, &vattr, context) == 0) {
-        e->owner_uid = vattr.va_uid;
-        e->owner_gid = vattr.va_gid;
-        e->mode = vattr.va_mode;
-        e->create_time = vattr.va_create_time.tv_sec;
-        e->access_time = vattr.va_access_time.tv_sec;
-        e->modify_time = vattr.va_modify_time.tv_sec;
-        e->change_time = vattr.va_change_time.tv_sec;
-      }
-
-      vfs_context_rele(context);
-    }
-
-    e->uid = kauth_cred_getruid(credential);
-    e->euid = kauth_cred_getuid(credential);
-
-    e->gid = kauth_cred_getrgid(credential);
-    e->egid = kauth_cred_getgid(credential);
-
-    vn_getpath(vp, e->path, &path_len);
-
-    osquery_cqueue_commit(&osquery.cqueue, e);
-  }
-  return KAUTH_RESULT_DEFER;
-}
-
 static inline void setup_locks() {
   /* Create locks.  Cannot be done on the stack. */
   osquery.lck_grp_attr = lck_grp_attr_alloc_init();
@@ -150,30 +83,33 @@ static inline void teardown_locks() {
 }
 
 static void unsubscribe_all_events() {
-  if (osquery.fileop_listener) {
-    kauth_unlisten_scope(osquery.fileop_listener);
-    osquery.fileop_listener = NULL;
+  for (int i = 0; i < OSQUERY_NUM_EVENTS; i++) {
+    if (osquery_publishers[i]) {
+      osquery_publishers[i]->unsubscribe();
+    }
   }
 }
 
-static int subscribe_to_event(osquery_event_t event, int subscribe) {
+static int subscribe_to_event(osquery_event_t event,
+                              int subscribe,
+                              void *udata) {
   if (osquery.buffer == NULL) {
     return -EINVAL;
   }
-
-  switch (event) {
-  case OSQUERY_PROCESS_EVENT:
-    if (subscribe && osquery.fileop_listener == NULL) {
-      osquery.fileop_listener =
-          kauth_listen_scope(KAUTH_SCOPE_FILEOP, fileop_scope_callback, NULL);
-    } else if (!subscribe && osquery.fileop_listener) {
-      kauth_unlisten_scope(osquery.fileop_listener);
-      osquery.fileop_listener = NULL;
-    }
-    break;
-  default:
+  if (!(OSQUERY_NULL_EVENT < event && event < OSQUERY_NUM_EVENTS)) {
     return -EINVAL;
   }
+  if (!osquery_publishers[event]) {
+    return -EINVAL;
+  }
+
+  if (subscribe) {
+    if (osquery_publishers[event]->subscribe(&osquery.cqueue, udata)) {
+      return -EINVAL;
+    }
+  } else {
+    osquery_publishers[event]->unsubscribe();
+  }
 
   return 0;
 }
@@ -342,7 +278,7 @@ static int osquery_ioctl(dev_t dev, u_long cmd, caddr_t data,
   switch (cmd) {
     case OSQUERY_IOCTL_SUBSCRIPTION:
       sub = (osquery_subscription_args_t *)data;
-      if ((err = subscribe_to_event(sub->event, sub->subscribe))) {
+      if ((err = subscribe_to_event(sub->event, sub->subscribe, sub->udata))) {
         goto error_exit;
       }
       break;
@@ -365,6 +301,12 @@ static int osquery_ioctl(dev_t dev, u_long cmd, caddr_t data,
     case OSQUERY_IOCTL_BUF_ALLOCATE:
       alloc = (osquery_buf_allocate_args_t *)data;
 
+      if (alloc->version != OSQUERY_KERNEL_COMM_VERSION) {
+        // Daemon tried connecting with incorrect version number.
+        err = -EINVAL;
+        goto error_exit;
+      }
+
       if (osquery.buffer != NULL) {
         // We don't want to allocate a second buffer.
         err = -EINVAL;

kernel/src/publishers.h

@@ -0,0 +1,54 @@
+/*
+ *  Copyright (c) 2014, Facebook, Inc.
+ *  All rights reserved.
+ *
+ *  This source code is licensed under the BSD-style license found in the
+ *  LICENSE file in the root directory of this source tree. An additional grant
+ *  of patent rights can be found in the PATENTS file in the same directory.
+ *
+ */
+
+#include <feeds.h>
+#include "circular_queue_kern.h"
+
+/** @brief Subscribe function type.
+ *
+ *  This function type is called when someone subscribes to a publisher.  It
+ *  should initialize all event callbacks and start publishing events to the
+ *  queue.
+ *
+ *  @param queue The queue to publish to.  A subscriber will only publish to the
+ *         last queue (not an issue as there should only be one queue).
+ *  @param udata Pointer to user data.  This is in user space and must be
+ *         copied down to kernel space before use.  A publisher may use this for
+ *         any additional data it wants from user space.
+ *  @return 0 on success, negative on failure.
+ */
+typedef int (*osquery_subscriber_t)(osquery_cqueue_t *queue, void *udata);
+/** @brief Unsubscribe function type.
+ *
+ *  Functions of this type stop a publisher from publishing events to the queue
+ *  as soon as possible.
+ *
+ *  @return Void.
+ */
+typedef void (*osquery_unsubscriber_t)();
+
+/** @brief A kernel publisher must provide the following function pointers.
+ */
+typedef struct {
+  osquery_subscriber_t subscribe;
+  osquery_unsubscriber_t unsubscribe;
+} osquery_kernel_event_publisher_t;
+
+//
+// Event publisher structs defined in implementations.
+//
+extern osquery_kernel_event_publisher_t process_events_publisher;
+
+/** @brief List of the kernel event publishers.
+ */
+static osquery_kernel_event_publisher_t
+    *osquery_publishers[OSQUERY_NUM_EVENTS] = {
+  [OSQUERY_PROCESS_EVENT] = &process_events_publisher
+};

kernel/src/publishers/darwin/process_events.c

@@ -0,0 +1,105 @@
+/*
+ *  Copyright (c) 2014, Facebook, Inc.
+ *  All rights reserved.
+ *
+ *  This source code is licensed under the BSD-style license found in the
+ *  LICENSE file in the root directory of this source tree. An additional grant
+ *  of patent rights can be found in the PATENTS file in the same directory.
+ *
+ */
+
+#include <sys/proc.h>
+#include <sys/systm.h>
+#include <sys/kauth.h>
+#include <sys/vnode.h>
+
+#include "publishers.h"
+
+static osquery_cqueue_t *cqueue = NULL;
+static kauth_listener_t fileop_listener = NULL;
+
+static int fileop_scope_callback(kauth_cred_t credential,
+                                 void *idata,
+                                 kauth_action_t action,
+                                 uintptr_t arg0,
+                                 uintptr_t arg1,
+                                 uintptr_t arg2,
+                                 uintptr_t arg3) {
+  vnode_t vp = (vnode_t)arg0;
+  if (action == KAUTH_FILEOP_EXEC && vp != NULL) {
+    // Someone is executing a file.
+    int path_len = MAXPATHLEN;
+
+    osquery_process_event_t *e =
+        (osquery_process_event_t *)osquery_cqueue_reserve(
+            cqueue, OSQUERY_PROCESS_EVENT);
+    if (e == NULL) {
+      // Failed to reserve space for the event.
+      return KAUTH_RESULT_DEFER;
+    }
+    e->pid = proc_selfpid();
+    e->ppid = proc_selfppid();
+    e->owner_uid = 0;
+    e->owner_gid = 0;
+    e->mode = -1;
+    vfs_context_t context = vfs_context_create(NULL);
+    if (context) {
+      struct vnode_attr vattr = {0};
+      VATTR_INIT(&vattr);
+      VATTR_WANTED(&vattr, va_uid);
+      VATTR_WANTED(&vattr, va_gid);
+      VATTR_WANTED(&vattr, va_mode);
+      VATTR_WANTED(&vattr, va_create_time);
+      VATTR_WANTED(&vattr, va_access_time);
+      VATTR_WANTED(&vattr, va_modify_time);
+      VATTR_WANTED(&vattr, va_change_time);
+
+      if (vnode_getattr(vp, &vattr, context) == 0) {
+        e->owner_uid = vattr.va_uid;
+        e->owner_gid = vattr.va_gid;
+        e->mode = vattr.va_mode;
+        e->create_time = vattr.va_create_time.tv_sec;
+        e->access_time = vattr.va_access_time.tv_sec;
+        e->modify_time = vattr.va_modify_time.tv_sec;
+        e->change_time = vattr.va_change_time.tv_sec;
+      }
+
+      vfs_context_rele(context);
+    }
+
+    e->uid = kauth_cred_getruid(credential);
+    e->euid = kauth_cred_getuid(credential);
+
+    e->gid = kauth_cred_getrgid(credential);
+    e->egid = kauth_cred_getgid(credential);
+
+    vn_getpath(vp, e->path, &path_len);
+
+    osquery_cqueue_commit(cqueue, e);
+  }
+  return KAUTH_RESULT_DEFER;
+}
+
+static int subscribe(osquery_cqueue_t *queue, void *udata) {
+  cqueue = queue;
+  if (fileop_listener != NULL) {
+    return -1;
+  }
+
+  fileop_listener =
+      kauth_listen_scope(KAUTH_SCOPE_FILEOP, fileop_scope_callback, NULL);
+
+  return 0;
+}
+
+static void unsubscribe() {
+  if (fileop_listener) {
+    kauth_unlisten_scope(fileop_listener);
+    fileop_listener = NULL;
+  }
+}
+
+osquery_kernel_event_publisher_t process_events_publisher = {
+  .subscribe = &subscribe,
+  .unsubscribe = &unsubscribe
+};

osquery/events/kernel.cpp

@@ -40,7 +40,7 @@ void KernelEventPublisher::configure() {
   for (const auto &sub : subscriptions_) {
     if (queue_ != nullptr) {
       auto sc = getSubscriptionContext(sub->context);
-      queue_->subscribe(sc->event_type);
+      queue_->subscribe(sc->event_type, sc->udata);
     }
   }
 }

osquery/events/kernel.h

@@ -23,6 +23,9 @@ namespace osquery {
 struct KernelSubscriptionContext : public SubscriptionContext {
   /// The kernel event subscription type.
   osquery_event_t event_type;
+
+  /// Data to pass to the kernel.
+  void *udata;
 };
 
 /**

osquery/events/kernel/circular_queue_user.cpp

@@ -27,6 +27,7 @@ CQueue::CQueue(size_t size) {
   osquery_buf_allocate_args_t alloc;
   alloc.size = size;
   alloc.buffer = NULL;
+  alloc.version = OSQUERY_KERNEL_COMM_VERSION;
 
   fd_ = open(filename, O_RDWR);
   if (fd_ < 0) {
@@ -50,10 +51,11 @@ CQueue::~CQueue() {
   }
 }
 
-void CQueue::subscribe(osquery_event_t event) {
+void CQueue::subscribe(osquery_event_t event, void *udata) {
   osquery_subscription_args_t sub;
   sub.event = event;
   sub.subscribe = 1;
+  sub.udata = udata;
 
   if (ioctl(fd_, OSQUERY_IOCTL_SUBSCRIPTION, &sub)) {
     throw CQueueException("Could not subscribe to event.");

osquery/events/kernel/circular_queue_user.h

@@ -55,8 +55,9 @@ class CQueue {
    * This sets up the event callbacks so we start hearing about the given event.
    *
    * @param event The event we are interested in.
+   * @param udata Pointer to udata for the event.  This is for additional info.
    */
-  void subscribe(osquery_event_t event);
+  void subscribe(osquery_event_t event, void *udata);
 
   /**
    * @brief Dequeue's an event from the shared buffer.

osquery/tables/events/process_events.cpp

@@ -28,6 +28,7 @@ REGISTER(ProcessEventSubscriber, "event_subscriber", "process_events");
 Status ProcessEventSubscriber::init() {
   auto sc = createSubscriptionContext();
   sc->event_type = OSQUERY_PROCESS_EVENT;
+  sc->udata = NULL;
   subscribe(&ProcessEventSubscriber::Callback, sc, NULL);
 
   return Status(0, "OK");