Security-57031.1.35.tar.gz

[apple/security.git] / securityd / src / SharedMemoryServer.cpp

diff --git a/securityd/src/SharedMemoryServer.cpp b/securityd/src/SharedMemoryServer.cpp
new file mode 100644 (file)
index 0000000..699542c
--- /dev/null
+++ b/securityd/src/SharedMemoryServer.cpp
@@ -0,0 +1,169 @@
+#include "SharedMemoryServer.h"
+#include <stdlib.h>
+#include <sys/mman.h>
+#include <fcntl.h>
+#include <machine/byte_order.h>
+#include <string>
+#include <sys/stat.h>
+#include <security_utilities/crc.h>
+#include <unistd.h>
+
+static const char* kPrefix = "/private/var/db/mds/messages/se_";
+
+SharedMemoryServer::SharedMemoryServer (const char* segmentName, SegmentOffsetType segmentSize) :
+       mSegmentName (segmentName), mSegmentSize (segmentSize)
+{
+       mFileName = kPrefix;
+       mFileName += segmentName;
+       
+       // make the mds directory, just in case it doesn't exist
+       mkdir("/var/db/mds", 1777);
+       mkdir("/var/db/mds/messages", 0755);
+       
+       // make the file name
+       // clean any old file away
+       unlink (mFileName.c_str ());
+       
+       // open the file
+       int segmentDescriptor = open (mFileName.c_str (), O_RDWR | O_CREAT, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
+       if (segmentDescriptor < 0)
+       {
+               return;
+       }
+       
+       // set the segment size
+       ftruncate (segmentDescriptor, segmentSize);
+       
+       // map it into memory
+       mSegment = (u_int8_t*) mmap (NULL, mSegmentSize, PROT_READ | PROT_WRITE, MAP_SHARED, segmentDescriptor, 0);
+       close (segmentDescriptor);
+
+       if (mSegment == (u_int8_t*) -1) // can't map the memory?
+       {
+               mSegment = NULL;
+               unlink (mFileName.c_str());
+       }
+       
+       mDataPtr = mDataArea = mSegment + sizeof(SegmentOffsetType);
+       mDataMax = mSegment + segmentSize;;
+       
+       SetProducerOffset (0);
+}
+
+
+
+SharedMemoryServer::~SharedMemoryServer ()
+{
+       // go away
+       if (mSegment == NULL)
+       {
+               return;
+       }
+       
+       // get out of memory
+       munmap (mSegment, mSegmentSize);
+       
+       // mark the segment for deletion
+       unlink (mFileName.c_str ());
+}
+
+
+
+const SegmentOffsetType
+       kSegmentLength = 0,
+       kCRCOffset = kSegmentLength + sizeof(SegmentOffsetType),
+       kDomainOffset = kCRCOffset + sizeof(SegmentOffsetType),
+       kEventTypeOffset = kDomainOffset + sizeof(SegmentOffsetType),
+       kHeaderLength = kEventTypeOffset + sizeof(SegmentOffsetType) - kCRCOffset;
+
+void SharedMemoryServer::WriteMessage (SegmentOffsetType domain, SegmentOffsetType event, const void *message, SegmentOffsetType messageLength)
+{
+       // assemble the final message
+       ssize_t messageSize = kHeaderLength + messageLength;
+       u_int8_t finalMessage[messageSize];
+       SegmentOffsetType *fm  = (SegmentOffsetType*) finalMessage;
+       fm[0] = OSSwapHostToBigInt32(domain);
+       fm[1] = OSSwapHostToBigInt32(event);
+       memcpy(&fm[2], message, messageLength);
+       
+       SegmentOffsetType crc = CalculateCRC(finalMessage, messageSize);
+       
+       // write the length
+       WriteOffset(messageSize);
+       
+       // write the crc
+       WriteOffset(crc);
+       
+       // write the data
+       WriteData (finalMessage, messageSize);
+       
+       // write the data count
+       SetProducerOffset(mDataPtr - mDataArea);
+}
+
+
+
+const char* SharedMemoryServer::GetSegmentName ()
+{
+       return mSegmentName.c_str ();
+}
+
+
+
+size_t SharedMemoryServer::GetSegmentSize ()
+{
+       return mSegmentSize;
+}
+
+
+
+SegmentOffsetType SharedMemoryServer::GetProducerOffset ()
+{
+       // the data is stored in the buffer in network byte order
+       u_int32_t pCount = OSSwapBigToHostInt32 (*(u_int32_t*) mSegment);
+       return OSSwapHostToBigInt32 (pCount);
+}
+
+
+
+void SharedMemoryServer::SetProducerOffset (SegmentOffsetType producerCount)
+{
+       *((SegmentOffsetType*) mSegment) = OSSwapHostToBigInt32 (producerCount);
+}
+
+
+
+void SharedMemoryServer::WriteOffset(SegmentOffsetType offset)
+{
+       u_int8_t buffer[4];
+       *((u_int32_t*) buffer) = OSSwapHostToBigInt32(offset);
+       WriteData(buffer, 4);
+}
+
+
+
+void SharedMemoryServer::WriteData(const void* data, SegmentOffsetType length)
+{
+       // figure out where in the buffer we actually need to write the data
+       // figure out how many bytes we can write without overflowing the buffer
+       const u_int8_t* dp = (const u_int8_t*) data;
+       SegmentOffsetType bytesToEnd = mDataMax - mDataPtr;
+       
+       // figure out how many bytes we can write
+       SegmentOffsetType bytesToWrite = (length <= bytesToEnd) ? length : bytesToEnd;
+
+       // move the first part of the data, making sure to skip the producer pointer
+       memcpy (mDataPtr, dp, bytesToWrite);
+       mDataPtr += bytesToWrite;
+       dp += bytesToWrite;
+       
+       // deduct the bytes just written
+       length -= bytesToWrite;
+       
+       if (length != 0) // did we wrap around?
+       {
+               mDataPtr = mDataArea;
+               memcpy (mDataPtr, dp, length);
+               mDataPtr += length;
+       }
+}