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cpp/ql/src/experimental/Security/CWE/CWE-377/InsecureTemporaryFile.cpp

@@ -0,0 +1,14 @@
+...
+  fp = fopen("/tmp/name.tmp","w"); // BAD
+...
+  char filename = tmpnam(NULL);
+  fp = fopen(filename,"w"); // BAD
+...
+
+  strcat (filename, "/tmp/name.XXXXXX");
+  fd = mkstemp(filename);
+  if ( fd < 0 ) {
+    return error;
+  }
+  fp = fdopen(fd,"w") // GOOD
+...

cpp/ql/src/experimental/Security/CWE/CWE-377/InsecureTemporaryFile.qhelp

@@ -0,0 +1,22 @@
+<!DOCTYPE qhelp PUBLIC
+  "-//Semmle//qhelp//EN"
+  "qhelp.dtd">
+<qhelp>
+<overview>
+<p>Working with a file, without checking its existence and its rights, as well as working with names that can be predicted, may not be safe. Requires the attention of developers.</p>
+
+</recommendation>
+<example>
+<p>The following example demonstrates erroneous and corrected work with file.</p>
+<sample src="InsecureTemporaryFile.cpp" />
+
+</example>
+<references>
+
+<li>
+  CERT C Coding Standard:
+  <a href="https://wiki.sei.cmu.edu/confluence/display/c/CON33-C.+Avoid+race+conditions+when+using+library+functions">CON33-C. Avoid race conditions when using library functions</a>.
+</li>
+
+</references>
+</qhelp>

cpp/ql/src/experimental/Security/CWE/CWE-377/InsecureTemporaryFile.ql

@@ -0,0 +1,98 @@
+/**
+ * @name Find insecure work with the file name.
+ * @description The file can be used to influence the correct operation of the program.
+ * @kind problem
+ * @id cpp/insecure-work-with-file-name
+ * @problem.severity warning
+ * @precision medium
+ * @tags correctness
+ *       security
+ *       external/cwe/cwe-377
+ */
+
+import cpp
+import semmle.code.cpp.valuenumbering.GlobalValueNumbering
+
+/** Holds for a function `f` that has an argument at index `apos` used to read the file. */
+predicate numberArgumentRead(Function f, int apos) {
+  f.hasGlobalOrStdName("fgets") and apos = 2
+  or
+  f.hasGlobalOrStdName("fread") and apos = 3
+  or
+  f.hasGlobalOrStdName("read") and apos = 0
+  or
+  f.hasGlobalOrStdName("fscanf") and apos = 0
+}
+
+/** Holds for a function `f` that has an argument at index `apos` used to write to file */
+predicate numberArgumentWrite(Function f, int apos) {
+  f.hasGlobalOrStdName("fprintf") and apos = 0
+  or
+  f.hasGlobalOrStdName("fputs") and apos = 1
+  or
+  f.hasGlobalOrStdName("write") and apos = 0
+  or
+  f.hasGlobalOrStdName("fwrite") and apos = 3
+  or
+  f.hasGlobalOrStdName("fflush") and apos = 0
+}
+
+from FunctionCall fc, string msg
+where
+  (
+    fc.getTarget().hasGlobalOrStdName("tmpnam") or
+    fc.getTarget().hasGlobalOrStdName("tmpnam_s") or
+    fc.getTarget().hasGlobalOrStdName("tmpnam_r")
+  ) and
+  not exists(FunctionCall fctmp |
+    fctmp.getTarget().hasGlobalOrStdName("mktemp") or
+    fctmp.getTarget().hasGlobalOrStdName("mkstemp") or
+    fctmp.getTarget().hasGlobalOrStdName("mkstemps") or
+    fctmp.getTarget().hasGlobalOrStdName("mkdtemp")
+  ) and
+  msg =
+    "Finding the name of a file that does not exist does not mean that it will not be exist at the next operation."
+  or
+  (
+    fc.getTarget().hasGlobalOrStdName("fopen") or
+    fc.getTarget().hasGlobalOrStdName("open")
+  ) and
+  fc.getNumberOfArguments() = 2 and
+  exists(FunctionCall fctmp, int i |
+    numberArgumentWrite(fctmp.getTarget(), i) and
+    globalValueNumber(fc) = globalValueNumber(fctmp.getArgument(i))
+  ) and
+  not exists(FunctionCall fctmp, int i |
+    numberArgumentRead(fctmp.getTarget(), i) and
+    globalValueNumber(fc) = globalValueNumber(fctmp.getArgument(i))
+  ) and
+  exists(FunctionCall fctmp |
+    (
+      fctmp.getTarget().hasGlobalOrStdName("strcat") or
+      fctmp.getTarget().hasGlobalOrStdName("strcpy")
+    ) and
+    globalValueNumber(fc.getArgument(0)) = globalValueNumber(fctmp.getAnArgument())
+    or
+    fctmp.getTarget().hasGlobalOrStdName("getenv") and
+    globalValueNumber(fc.getArgument(0)) = globalValueNumber(fctmp)
+    or
+    (
+      fctmp.getTarget().hasGlobalOrStdName("asprintf") or
+      fctmp.getTarget().hasGlobalOrStdName("vasprintf") or
+      fctmp.getTarget().hasGlobalOrStdName("xasprintf") or
+      fctmp.getTarget().hasGlobalOrStdName("xvasprintf ")
+    ) and
+    exists(Variable vrtmp |
+      vrtmp = fc.getArgument(0).(VariableAccess).getTarget() and
+      vrtmp = fctmp.getArgument(0).(AddressOfExpr).getAddressable().(Variable) and
+      not vrtmp instanceof Field
+    )
+  ) and
+  not exists(FunctionCall fctmp |
+    fctmp.getTarget().hasGlobalOrStdName("umask") or
+    fctmp.getTarget().hasGlobalOrStdName("fchmod") or
+    fctmp.getTarget().hasGlobalOrStdName("chmod")
+  ) and
+  msg =
+    "Сreating a file for writing without evaluating its existence and setting permissions can be unsafe."
+select fc, msg