centos 7
tmpfile weakness #34

4

Weakness Breakdown


Definition:

A temporary file weakness occurs when a temporary file that is created and used by a high-privilege process is accidentally shared with a low-privilege process, on account of it being temporary and generated after all security controls have been applied. This allows the low-privilege process to read data from the high-privilege process (information leakage), or worse, influence the high-privilege process by modifying the shared temporary file.

Warning code(s):

Temporary file race condition.

File Name:

snapper-0.2.8/snapper/Comparison.cc

Context:

The highlighted line of code below is the trigger point of this particular Centos 7 tmpfile weakness.

     }


    void
    Comparison::save()
    {
	y2mil("num1:" << getSnapshot1()->getNum() << " num2:" << getSnapshot2()->getNum());

	if (getSnapshot1()->isCurrent() || getSnapshot2()->isCurrent())
	    throw IllegalSnapshotException();

	unsigned int num1 = getSnapshot1()->getNum();
	unsigned int num2 = getSnapshot2()->getNum();

	bool invert = num1 > num2;

	if (invert)
	    swap(num1, num2);

	string file_name = "filelist-" + decString(num1) + ".txt";
	string tmp_name = file_name + ".tmp-XXXXXX";

	SDir info_dir = invert ? getSnapshot1()->openInfoDir() : getSnapshot2()->openInfoDir();

	FILE* file = fdopen(info_dir.mktemp(tmp_name), "w");
	if (!file)
	{
	    y2err("mkstemp failed errno:" << errno << " (" << stringerror(errno) << ")");
	    throw IOErrorException();
	}

	for (Files::const_iterator it = files.begin(); it != files.end(); ++it)
	{
	    unsigned int status = it->getPreToPostStatus();

	    if (invert)
		status = invertStatus(status);

	    fprintf(file, "%s %s\n", statusToString(status).c_str(), it->getName().c_str());
	}

	fclose(file);

	info_dir.rename(tmp_name, file_name);
    }


    void
    Comparison::filter()
    { 

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