Bug 1806899 - Detect link escapes in safe_extract (all m-c) r=jcristau

Apply the link escape check from tooltool to all the m-c tarfile extractions previously updated.

Differential Revision: https://phabricator.services.mozilla.com/D170660

dom/media/webrtc/third_party_build/vendor-libwebrtc.py

@@ -139,19 +139,23 @@ def fetch_local(target, path, commit):
 
 def validate_tar_member(member, path):
     def _is_within_directory(directory, target):
-        abs_directory = os.path.abspath(directory)
-        abs_target = os.path.abspath(target)
-        prefix = os.path.commonprefix([abs_directory, abs_target])
-        return prefix == abs_directory
+        real_directory = os.path.realpath(directory)
+        real_target = os.path.realpath(target)
+        prefix = os.path.commonprefix([real_directory, real_target])
+        return prefix == real_directory
 
     member_path = os.path.join(path, member.name)
     if not _is_within_directory(path, member_path):
         raise Exception("Attempted path traversal in tar file: " + member.name)
+    if member.issym():
+        link_path = os.path.join(os.path.dirname(member_path), member.linkname)
+        if not _is_within_directory(path, link_path):
+            raise Exception("Attempted link path traversal in tar file: " + member.name)
     if member.mode & (stat.S_ISUID | stat.S_ISGID):
         raise Exception("Attempted setuid or setgid in tar file: " + member.name)
 
 
-def safe_extract(tar, path=".", members=None, *, numeric_owner=False):
+def safe_extract(tar, path=".", *, numeric_owner=False):
     def _files(tar, path):
         for member in tar:
             validate_tar_member(member, path)

python/mozbuild/mozbuild/action/tooltool.py

@@ -958,19 +958,23 @@ CHECKSUM_SUFFIX = ".checksum"
 
 def validate_tar_member(member, path):
     def _is_within_directory(directory, target):
-        abs_directory = os.path.abspath(directory)
-        abs_target = os.path.abspath(target)
-        prefix = os.path.commonprefix([abs_directory, abs_target])
-        return prefix == abs_directory
+        real_directory = os.path.realpath(directory)
+        real_target = os.path.realpath(target)
+        prefix = os.path.commonprefix([real_directory, real_target])
+        return prefix == real_directory
 
     member_path = os.path.join(path, member.name)
     if not _is_within_directory(path, member_path):
         raise Exception("Attempted path traversal in tar file: " + member.name)
+    if member.issym():
+        link_path = os.path.join(os.path.dirname(member_path), member.linkname)
+        if not _is_within_directory(path, link_path):
+            raise Exception("Attempted link path traversal in tar file: " + member.name)
     if member.mode & (stat.S_ISUID | stat.S_ISGID):
         raise Exception("Attempted setuid or setgid in tar file: " + member.name)
 
 
-def safe_extract(tar, path=".", members=None, *, numeric_owner=False):
+def safe_extract(tar, path=".", *, numeric_owner=False):
     def _files(tar, path):
         for member in tar:
             validate_tar_member(member, path)

python/mozbuild/mozbuild/vendor/vendor_manifest.py

@@ -366,11 +366,34 @@ class VendorManifest(MozbuildObject):
     def fetch_and_unpack(self, revision):
         """Fetch and unpack upstream source"""
 
-        def _is_within_directory(directory, target):
-            abs_directory = os.path.abspath(directory)
-            abs_target = os.path.abspath(target)
-            prefix = os.path.commonprefix([abs_directory, abs_target])
-            return prefix == abs_directory
+        def validate_tar_member(member, path):
+            def is_within_directory(directory, target):
+                real_directory = os.path.realpath(directory)
+                real_target = os.path.realpath(target)
+                prefix = os.path.commonprefix([real_directory, real_target])
+                return prefix == real_directory
+
+            member_path = os.path.join(path, member.name)
+            if not is_within_directory(path, member_path):
+                raise Exception("Attempted path traversal in tar file: " + member.name)
+            if member.issym():
+                link_path = os.path.join(os.path.dirname(member_path), member.linkname)
+                if not is_within_directory(path, link_path):
+                    raise Exception(
+                        "Attempted link path traversal in tar file: " + member.name
+                    )
+            if member.mode & (stat.S_ISUID | stat.S_ISGID):
+                raise Exception(
+                    "Attempted setuid or setgid in tar file: " + member.name
+                )
+
+        def safe_extract(tar, path=".", *, numeric_owner=False):
+            def _files(tar, path):
+                for member in tar:
+                    validate_tar_member(member, path)
+                    yield member
+
+            tar.extractall(path, members=_files(tar, path), numeric_owner=numeric_owner)
 
         url = self.source_host.upstream_snapshot(revision)
         self.logInfo({"url": url}, "Fetching code archive from {url}")
@@ -383,20 +406,6 @@ class VendorManifest(MozbuildObject):
                     tmptarfile.write(data)
                 tmptarfile.seek(0)
 
-                tar = tarfile.open(tmptarfile.name)
-
-                for member in tar:
-                    member_path = os.path.join(tmpextractdir.name, member.name)
-                    if not _is_within_directory(tmpextractdir.name, member_path):
-                        raise Exception(
-                            "Tar archive contains non-local paths, e.g. '%s'"
-                            % member.name
-                        )
-                    if member.mode & (stat.S_ISUID | stat.S_ISGID):
-                        raise Exception(
-                            "Tar archive has setuid or setgid member '%s'" % member.name
-                        )
-
                 vendor_dir = mozpath.normsep(
                     self.manifest["vendoring"]["vendor-directory"]
                 )
@@ -420,17 +429,18 @@ class VendorManifest(MozbuildObject):
                         mozfile.remove(file)
 
                 self.logInfo({"vd": vendor_dir}, "Unpacking upstream files for {vd}.")
-                tar.extractall(tmpextractdir.name)
+                with tarfile.open(tmptarfile.name) as tar:
 
-                def get_first_dir(p):
-                    halves = os.path.split(p)
-                    return get_first_dir(halves[0]) if halves[0] else halves[1]
+                    safe_extract(tar, tmpextractdir.name)
 
-                one_prefix = get_first_dir(tar.getnames()[0])
-                has_prefix = all(
-                    map(lambda name: name.startswith(one_prefix), tar.getnames())
-                )
-                tar.close()
+                    def get_first_dir(p):
+                        halves = os.path.split(p)
+                        return get_first_dir(halves[0]) if halves[0] else halves[1]
+
+                    one_prefix = get_first_dir(tar.getnames()[0])
+                    has_prefix = all(
+                        map(lambda name: name.startswith(one_prefix), tar.getnames())
+                    )
 
                 # GitLab puts everything down a directory; move it up.
                 if has_prefix:

testing/mozbase/mozfile/mozfile/mozfile.py

@@ -42,10 +42,10 @@ def extract_tarball(src, dest, ignore=None):
     import tarfile
 
     def _is_within_directory(directory, target):
-        abs_directory = os.path.abspath(directory)
-        abs_target = os.path.abspath(target)
-        prefix = os.path.commonprefix([abs_directory, abs_target])
-        return prefix == abs_directory
+        real_directory = os.path.realpath(directory)
+        real_target = os.path.realpath(target)
+        prefix = os.path.commonprefix([real_directory, real_target])
+        return prefix == real_directory
 
     with tarfile.open(src) as bundle:
         namelist = []
@@ -65,6 +65,20 @@ def extract_tarball(src, dest, ignore=None):
                     """
                     )
                 )
+            if m.issym():
+                link_path = os.path.join(os.path.dirname(member_path), m.linkname)
+                if not _is_within_directory(dest, link_path):
+                    raise RuntimeError(
+                        dedent(
+                            f"""
+                    Tar bundle '{src}' may be maliciously crafted to escape the destination!
+                    The following path was detected:
+
+                      {m.name}
+                        """
+                        )
+                    )
+
             if m.mode & (stat.S_ISUID | stat.S_ISGID):
                 raise RuntimeError(
                     dedent(

testing/mozharness/mozharness/base/script.py

@@ -93,22 +93,29 @@ class ContentLengthMismatch(Exception):
 
 def _validate_tar_member(member, path):
     def _is_within_directory(directory, target):
-        abs_directory = os.path.abspath(directory)
-        abs_target = os.path.abspath(target)
-        prefix = os.path.commonprefix([abs_directory, abs_target])
-        return prefix == abs_directory
+        real_directory = os.path.realpath(directory)
+        real_target = os.path.realpath(target)
+        prefix = os.path.commonprefix([real_directory, real_target])
+        return prefix == real_directory
 
     member_path = os.path.join(path, member.name)
     if not _is_within_directory(path, member_path):
         raise Exception("Attempted path traversal in tar file: " + member.name)
+    if member.issym():
+        link_path = os.path.join(os.path.dirname(member_path), member.linkname)
+        if not _is_within_directory(path, link_path):
+            raise Exception("Attempted link path traversal in tar file: " + member.name)
     if member.mode & (stat.S_ISUID | stat.S_ISGID):
         raise Exception("Attempted setuid or setgid in tar file: " + member.name)
 
 
-def _safe_extract(tar, path=".", members=None, *, numeric_owner=False):
-    for member in tar.getmembers():
-        _validate_tar_member(member, path)
-    tar.extractall(path, members, numeric_owner=numeric_owner)
+def _safe_extract(tar, path=".", *, numeric_owner=False):
+    def _files(tar, path):
+        for member in tar:
+            _validate_tar_member(member, path)
+            yield member
+
+    tar.extractall(path, members=_files(tar, path), numeric_owner=numeric_owner)
 
 
 def platform_name():

testing/mozharness/test/test_base_script.py

@@ -320,7 +320,13 @@ class TestScript(unittest.TestCase):
                     extract_to=self.tmpdir,
                 )
 
-        for archive in ("archive-setuid.tar", "archive-escape.tar"):
+        for archive in (
+            "archive-setuid.tar",
+            "archive-escape.tar",
+            "archive-link.tar",
+            "archive-link-abs.tar",
+            "archive-double-link.tar",
+        ):
             with self.assertRaises(Exception):
                 self.s.download_unpack(
                     url=os.path.join(archives_path, archive),
@@ -371,7 +377,13 @@ class TestScript(unittest.TestCase):
                     self.tmpdir,
                 )
 
-        for archive in ("archive-setuid.tar", "archive-escape.tar"):
+        for archive in (
+            "archive-setuid.tar",
+            "archive-escape.tar",
+            "archive-link.tar",
+            "archive-link-abs.tar",
+            "archive-double-link.tar",
+        ):
             with self.assertRaises(Exception):
                 self.s.unpack(os.path.join(archives_path, archive), self.tmpdir)