# HG changeset patch
# User Yuya Nishihara <yuya@tcha.org>
# Date 1546953576 -32400
# Node ID 83377b4b4ae0e9a6b8e579f7b0a693b8cf5c3b10
# Parent  6c10eba6b9cddab020de49fd4fabcb2cadcd85d0
subrepo: reject potentially unsafe subrepo paths (BC) (SEC)

In addition to the previous patch, this prohibits '~', '$nonexistent', etc.
for any subrepo types. I think this is safer, and real-world subrepos wouldn't
use such (local) paths.

diff -r 6c10eba6b9cd -r 83377b4b4ae0 mercurial/subrepo.py
--- a/mercurial/subrepo.py	Tue Jan 08 22:07:45 2019 +0900
+++ b/mercurial/subrepo.py	Tue Jan 08 22:19:36 2019 +0900
@@ -115,6 +115,10 @@
                 vfs.unlink(vfs.reljoin(dirname, f))
 
 def _auditsubrepopath(repo, path):
+    # sanity check for potentially unsafe paths such as '~' and '$FOO'
+    if path.startswith('~') or '$' in path or util.expandpath(path) != path:
+        raise error.Abort(_('subrepo path contains illegal component: %s')
+                          % path)
     # auditor doesn't check if the path itself is a symlink
     pathutil.pathauditor(repo.root)(path)
     if repo.wvfs.islink(path):

# HG changeset patch
# User Yuya Nishihara <yuya@tcha.org>
# Date 1546952865 -32400
# Node ID 6c10eba6b9cddab020de49fd4fabcb2cadcd85d0
# Parent  31286c9282dfa734e9da085649b7ae5a8ba290ad
subrepo: prohibit variable expansion on creation of hg subrepo (SEC)

It's probably wrong to expand path at localrepo.*repository() layer, but
fixing the layering issue would require careful inspection of call paths.
So, this patch adds add a validation to the subrepo constructor.

os.path.realpath(util.expandpath(root)) is what vfsmod.vfs() would do.

diff -r 31286c9282df -r 6c10eba6b9cd mercurial/subrepo.py
--- a/mercurial/subrepo.py	Tue Jan 08 21:51:54 2019 +0900
+++ b/mercurial/subrepo.py	Tue Jan 08 22:07:45 2019 +0900
@@ -403,7 +403,16 @@
         r = ctx.repo()
         root = r.wjoin(path)
         create = allowcreate and not r.wvfs.exists('%s/.hg' % path)
+        # repository constructor does expand variables in path, which is
+        # unsafe since subrepo path might come from untrusted source.
+        if os.path.realpath(util.expandpath(root)) != root:
+            raise error.Abort(_('subrepo path contains illegal component: %s')
+                              % path)
         self._repo = hg.repository(r.baseui, root, create=create)
+        if self._repo.root != root:
+            raise error.ProgrammingError('failed to reject unsafe subrepo '
+                                         'path: %s (expanded to %s)'
+                                         % (root, self._repo.root))
 
         # Propagate the parent's --hidden option
         if r is r.unfiltered():