Add shutil.unpack_archive and subprocess tar extraction as TarSlip sources and sinks

- Add test cases for shutil.unpack_archive and subprocess.run(["tar", ...]) to tarslip.py
- Add ShutilUnpackArchiveSource/Sink for shutil.unpack_archive calls with non-literal filenames
- Add SubprocessTarExtractionSource/Sink for subprocess calls invoking tar with extraction flags
- Update TarSlip.expected with expected test output for new cases

Agent-Logs-Url: https://github.com/github/codeql/sessions/f31a3622-9b18-415f-85f1-62ec14a8319f

Co-authored-by: hvitved <3667920+hvitved@users.noreply.github.com>

python/ql/lib/semmle/python/security/dataflow/TarSlipCustomizations.qll

@@ -132,6 +132,75 @@ module TarSlip {
     }
   }
 
+  /**
+   * A call to `shutil.unpack_archive`, considered as a flow source.
+   *
+   * The archive filename is not hardcoded, so it may come from user input.
+   */
+  class ShutilUnpackArchiveSource extends Source {
+    ShutilUnpackArchiveSource() {
+      this = API::moduleImport("shutil").getMember("unpack_archive").getACall() and
+      not this.(DataFlow::CallCfgNode).getArg(0).getALocalSource().asExpr() instanceof StringLiteral
+    }
+  }
+
+  /**
+   * A call to `shutil.unpack_archive`, considered as a flow sink.
+   *
+   * The archive filename is not hardcoded, so it may come from user input.
+   */
+  class ShutilUnpackArchiveSink extends Sink {
+    ShutilUnpackArchiveSink() {
+      this = API::moduleImport("shutil").getMember("unpack_archive").getACall() and
+      not this.(DataFlow::CallCfgNode).getArg(0).getALocalSource().asExpr() instanceof StringLiteral
+    }
+  }
+
+  /**
+   * Holds if `call` is a subprocess call that invokes `tar` for archive extraction
+   * with at least one non-literal argument (the archive filename).
+   *
+   * Detects patterns like `subprocess.run(["tar", "-xf", untrusted_filename])`.
+   */
+  private predicate isSubprocessTarExtraction(DataFlow::CallCfgNode call) {
+    exists(SequenceNode cmdList |
+      call =
+        API::moduleImport("subprocess")
+            .getMember(["run", "call", "check_call", "check_output", "Popen"])
+            .getACall() and
+      cmdList = call.getArg(0).asCfgNode() and
+      // Command must be "tar" (possibly with a full path like "/usr/bin/tar")
+      cmdList.getElement(0).getNode().(StringLiteral).getText().matches("%tar") and
+      // At least one extraction-related flag must be present
+      exists(string flag |
+        flag = cmdList.getElement(_).getNode().(StringLiteral).getText() and
+        (flag.matches("%-x%") or flag = "--extract")
+      ) and
+      // At least one non-literal argument (the archive filename)
+      exists(int i |
+        i > 0 and
+        exists(cmdList.getElement(i)) and
+        not cmdList.getElement(i).getNode() instanceof StringLiteral
+      )
+    )
+  }
+
+  /**
+   * A call to `subprocess` functions that invokes `tar` for archive extraction,
+   * considered as a flow source.
+   */
+  class SubprocessTarExtractionSource extends Source {
+    SubprocessTarExtractionSource() { isSubprocessTarExtraction(this) }
+  }
+
+  /**
+   * A call to `subprocess` functions that invokes `tar` for archive extraction,
+   * considered as a flow sink.
+   */
+  class SubprocessTarExtractionSink extends Sink {
+    SubprocessTarExtractionSink() { isSubprocessTarExtraction(this) }
+  }
+
   /**
    * Holds if `g` clears taint for `tarInfo`.
    *

python/ql/test/query-tests/Security/CWE-022-TarSlip/TarSlip.expected

@@ -53,6 +53,9 @@ nodes
 | tarslip.py:112:1:112:3 | ControlFlowNode for tar | semmle.label | ControlFlowNode for tar |
 | tarslip.py:112:7:112:39 | ControlFlowNode for Attribute() | semmle.label | ControlFlowNode for Attribute() |
 | tarslip.py:113:24:113:26 | ControlFlowNode for tar | semmle.label | ControlFlowNode for tar |
+| tarslip.py:122:1:122:49 | ControlFlowNode for Attribute() | semmle.label | ControlFlowNode for Attribute() |
+| tarslip.py:126:1:126:51 | ControlFlowNode for Attribute() | semmle.label | ControlFlowNode for Attribute() |
+| tarslip.py:127:1:127:58 | ControlFlowNode for Attribute() | semmle.label | ControlFlowNode for Attribute() |
 subpaths
 #select
 | tarslip.py:15:1:15:3 | ControlFlowNode for tar | tarslip.py:14:7:14:39 | ControlFlowNode for Attribute() | tarslip.py:15:1:15:3 | ControlFlowNode for tar | This file extraction depends on a $@. | tarslip.py:14:7:14:39 | ControlFlowNode for Attribute() | potentially untrusted source |
@@ -64,3 +67,6 @@ subpaths
 | tarslip.py:96:17:96:21 | ControlFlowNode for entry | tarslip.py:94:7:94:39 | ControlFlowNode for Attribute() | tarslip.py:96:17:96:21 | ControlFlowNode for entry | This file extraction depends on a $@. | tarslip.py:94:7:94:39 | ControlFlowNode for Attribute() | potentially untrusted source |
 | tarslip.py:110:1:110:3 | ControlFlowNode for tar | tarslip.py:109:7:109:39 | ControlFlowNode for Attribute() | tarslip.py:110:1:110:3 | ControlFlowNode for tar | This file extraction depends on a $@. | tarslip.py:109:7:109:39 | ControlFlowNode for Attribute() | potentially untrusted source |
 | tarslip.py:113:24:113:26 | ControlFlowNode for tar | tarslip.py:112:7:112:39 | ControlFlowNode for Attribute() | tarslip.py:113:24:113:26 | ControlFlowNode for tar | This file extraction depends on a $@. | tarslip.py:112:7:112:39 | ControlFlowNode for Attribute() | potentially untrusted source |
+| tarslip.py:122:1:122:49 | ControlFlowNode for Attribute() | tarslip.py:122:1:122:49 | ControlFlowNode for Attribute() | tarslip.py:122:1:122:49 | ControlFlowNode for Attribute() | This file extraction depends on a $@. | tarslip.py:122:1:122:49 | ControlFlowNode for Attribute() | potentially untrusted source |
+| tarslip.py:126:1:126:51 | ControlFlowNode for Attribute() | tarslip.py:126:1:126:51 | ControlFlowNode for Attribute() | tarslip.py:126:1:126:51 | ControlFlowNode for Attribute() | This file extraction depends on a $@. | tarslip.py:126:1:126:51 | ControlFlowNode for Attribute() | potentially untrusted source |
+| tarslip.py:127:1:127:58 | ControlFlowNode for Attribute() | tarslip.py:127:1:127:58 | ControlFlowNode for Attribute() | tarslip.py:127:1:127:58 | ControlFlowNode for Attribute() | This file extraction depends on a $@. | tarslip.py:127:1:127:58 | ControlFlowNode for Attribute() | potentially untrusted source |

python/ql/test/query-tests/Security/CWE-022-TarSlip/tarslip.py

@@ -114,3 +114,16 @@ tar.extractall(members=tar, filter=extraction_filter) # unsafe
 
 tar = tarfile.open(unsafe_filename_tar)
 tar.extractall(members=safemembers(tar), filter=extraction_filter) # safe -- we assume `safemembers` makes up for the unsafe filter
+
+import shutil
+import subprocess
+
+# shutil.unpack_archive
+shutil.unpack_archive(unsafe_filename_tar, "out") # unsafe
+shutil.unpack_archive("safe.tar", "out") # safe
+
+# subprocess tar extraction
+subprocess.run(["tar", "-xf", unsafe_filename_tar]) # unsafe
+subprocess.check_call(["tar", "-xf", unsafe_filename_tar]) # unsafe
+subprocess.run(["tar", "-xf", "safe.tar"]) # safe
+subprocess.run(["echo", unsafe_filename_tar]) # safe - not a tar extraction