X-Git-Url: http://git.lttng.org/?a=blobdiff_plain;f=libringbuffer%2Fshm.h;h=8987f72a30f3dc234cf2ca9d7b777c86b6197cf3;hb=1abcee5dc89230e8f9dca4b961e978fe6ac44954;hp=f5cc8e69a2b7a62faf9f614dec2489f99ccee96d;hpb=4746ae29409b78e96543a3b207c91a3c510c6476;p=lttng-ust.git

diff --git a/libringbuffer/shm.h b/libringbuffer/shm.h
index f5cc8e69..8987f72a 100644
--- a/libringbuffer/shm.h
+++ b/libringbuffer/shm.h
@@ -4,42 +4,60 @@
 /*
  * libringbuffer/shm.h
  *
- * Copyright 2011 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ * Copyright (C) 2011-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
  *
- * Dual LGPL v2.1/GPL v2 license.
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; only
+ * version 2.1 of the License.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
 #include <stdint.h>
-#include <ust/usterr-signal-safe.h>
-#include "ust/core.h"
+#include <usterr-signal-safe.h>
+#include <urcu/compiler.h>
 #include "shm_types.h"
 
 /*
  * Pointer dereferencing. We don't trust the shm_ref, so we validate
  * both the index and offset with known boundaries.
+ *
+ * "shmp" and "shmp_index" guarantee that it's safe to use the pointer
+ * target type, even in the occurrence of shm_ref modification by an
+ * untrusted process having write access to the shm_ref. We return a
+ * NULL pointer if the ranges are invalid.
  */
 static inline
 char *_shmp_offset(struct shm_object_table *table, struct shm_ref *ref,
-		   size_t offset)
+		   size_t idx, size_t elem_size)
 {
 	struct shm_object *obj;
-	size_t index, ref_offset;
+	size_t objindex, ref_offset;
 
-	index = (size_t) ref->index;
-	if (unlikely(index >= table->allocated_len))
+	objindex = (size_t) ref->index;
+	if (caa_unlikely(objindex >= table->allocated_len))
 		return NULL;
-	obj = &table->objects[index];
+	obj = &table->objects[objindex];
 	ref_offset = (size_t) ref->offset;
-	ref_offset += offset;
-	if (unlikely(ref_offset >= obj->memory_map_size))
+	ref_offset += idx * elem_size;
+	/* Check if part of the element returned would exceed the limits. */
+	if (caa_unlikely(ref_offset + elem_size > obj->memory_map_size))
 		return NULL;
 	return &obj->memory_map[ref_offset];
 }
 
-#define shmp_index(handle, ref, offset)					\
+#define shmp_index(handle, ref, index)					\
 	({								\
 		__typeof__((ref)._type) ____ptr_ret;			\
-		____ptr_ret = (__typeof__(____ptr_ret)) _shmp_offset((handle)->table, &(ref)._ref, ((offset) * sizeof(*____ptr_ret)));	\
+		____ptr_ret = (__typeof__(____ptr_ret)) _shmp_offset((handle)->table, &(ref)._ref, index, sizeof(*____ptr_ret));	\
 		____ptr_ret;						\
 	})
 
@@ -54,6 +72,8 @@ void _set_shmp(struct shm_ref *ref, struct shm_ref src)
 #define set_shmp(ref, src)	_set_shmp(&(ref)._ref, src)
 
 struct shm_object_table *shm_object_table_create(size_t max_nb_obj);
+struct shm_object *shm_object_table_append_shadow(struct shm_object_table *table,
+			int shm_fd, int wait_fd, size_t memory_map_size);
 void shm_object_table_destroy(struct shm_object_table *table);
 struct shm_object *shm_object_table_append(struct shm_object_table *table,
 					   size_t memory_map_size);
@@ -69,14 +89,14 @@ struct shm_ref zalloc_shm(struct shm_object *obj, size_t len);
 void align_shm(struct shm_object *obj, size_t align);
 
 static inline
-int shm_get_wakeup_fd(struct shm_handle *handle, struct shm_ref *ref)
+int shm_get_wakeup_fd(struct lttng_ust_shm_handle *handle, struct shm_ref *ref)
 {
 	struct shm_object_table *table = handle->table;
 	struct shm_object *obj;
 	size_t index;
 
 	index = (size_t) ref->index;
-	if (unlikely(index >= table->allocated_len))
+	if (caa_unlikely(index >= table->allocated_len))
 		return -EPERM;
 	obj = &table->objects[index];
 	return obj->wait_fd[1];
@@ -84,17 +104,35 @@ int shm_get_wakeup_fd(struct shm_handle *handle, struct shm_ref *ref)
 }
 
 static inline
-int shm_get_wait_fd(struct shm_handle *handle, struct shm_ref *ref)
+int shm_get_wait_fd(struct lttng_ust_shm_handle *handle, struct shm_ref *ref)
 {
 	struct shm_object_table *table = handle->table;
 	struct shm_object *obj;
 	size_t index;
 
 	index = (size_t) ref->index;
-	if (unlikely(index >= table->allocated_len))
+	if (caa_unlikely(index >= table->allocated_len))
 		return -EPERM;
 	obj = &table->objects[index];
 	return obj->wait_fd[0];
 }
 
+static inline
+int shm_get_object_data(struct lttng_ust_shm_handle *handle, struct shm_ref *ref,
+		int **shm_fd, int **wait_fd, uint64_t **memory_map_size)
+{
+	struct shm_object_table *table = handle->table;
+	struct shm_object *obj;
+	size_t index;
+
+	index = (size_t) ref->index;
+	if (caa_unlikely(index >= table->allocated_len))
+		return -EPERM;
+	obj = &table->objects[index];
+	*shm_fd = &obj->shm_fd;
+	*wait_fd = &obj->wait_fd[0];
+	*memory_map_size = &obj->allocated_len;
+	return 0;
+}
+
 #endif /* _LIBRINGBUFFER_SHM_H */