[Buildroot] [git commit branch/2018.02.x] utils/scanpypi: protect against zip-slip vulnerability in zip/tar handling
Peter Korsgaard
peter at korsgaard.com
Thu Feb 21 12:54:04 UTC 2019
commit: https://git.buildroot.net/buildroot/commit/?id=73192f7056684ef7eb9604cdf367a2da355e50b7
branch: https://git.buildroot.net/buildroot/commit/?id=refs/heads/2018.02.x
For details, see https://github.com/snyk/zip-slip-vulnerability
Older python versions do not validate that the extracted files are inside
the target directory. Detect and error out on evil paths before extracting
.zip / .tar file.
Given the scope of this (zip issue was fixed in python 2.7.4, released
2013-04-06, scanpypi is only used by a developer when adding a new python
package), the security impact is fairly minimal, but it is good to get it
fixed anyway.
Reported-by: Bas van Schaik <security-reports at semmle.com>
Signed-off-by: Peter Korsgaard <peter at korsgaard.com>
(cherry picked from commit a83e30ad63e00d6c81a6409161c2d3010d98d373)
Signed-off-by: Peter Korsgaard <peter at korsgaard.com>
---
utils/scanpypi | 18 ++++++++++++++++++
1 file changed, 18 insertions(+)
diff --git a/utils/scanpypi b/utils/scanpypi
index cb4b5e76a3..23e64e65ec 100755
--- a/utils/scanpypi
+++ b/utils/scanpypi
@@ -212,6 +212,22 @@ class BuildrootPackage():
self.filename = self.used_url['filename']
self.url = self.used_url['url']
+ def check_archive(self, members):
+ """
+ Check archive content before extracting
+
+ Keyword arguments:
+ members -- list of archive members
+ """
+ # Protect against https://github.com/snyk/zip-slip-vulnerability
+ # Older python versions do not validate that the extracted files are
+ # inside the target directory. Detect and error out on evil paths
+ evil = [e for e in members if os.path.relpath(e).startswith(('/', '..'))]
+ if evil:
+ print('ERROR: Refusing to extract {} with suspicious members {}'.format(
+ self.filename, evil))
+ sys.exit(1)
+
def extract_package(self, tmp_path):
"""
Extract the package contents into a directrory
@@ -233,6 +249,7 @@ class BuildrootPackage():
print('Removing {pkg}...'.format(pkg=tmp_pkg))
shutil.rmtree(tmp_pkg)
os.makedirs(tmp_pkg)
+ self.check_archive(as_zipfile.namelist())
as_zipfile.extractall(tmp_pkg)
pkg_filename = self.filename.split(".zip")[0]
else:
@@ -248,6 +265,7 @@ class BuildrootPackage():
print('Removing {pkg}...'.format(pkg=tmp_pkg))
shutil.rmtree(tmp_pkg)
os.makedirs(tmp_pkg)
+ self.check_archive(as_tarfile.getnames())
as_tarfile.extractall(tmp_pkg)
pkg_filename = self.filename.split(".tar")[0]
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